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2004-9087 G PASCO ENGINEERING, INC. 535 NORTH HIGHWAY 101, SUITE A SOLANA BEACH, CA 92075 (858) 259 -8212 WAYNE A. PASCO FAX (858) 259 -4812 R.C.E. 29577 February 8, 2005 PE 1275 City of Encinitas Engineering Services Permits 505 S. Vulcan Avenue Encinitas,CA 92024 RE: ENGINEER'S PAD CERTIFICATION FOR (9087 -G) To Whom It May Concern: Pursuant to section 23.24.3 10 of the Encinitas Municipal Code, this letter is hereby submitted as a Pad Certification Letter for the above referenced site. As the engineer for the subject project, I hereby state that the rough grading for this lot has been completed in conformance with the approved plan, or as shown on the attached redline bluelines and requirements of the City of Encinitas, Codes and Standards. Certification was performed on February 8, 2005. 23.24.310(B). The following list provides the pad elevations as field verified and shown on the approved grading plan. Pad Elevation Pad Elevation per Plan per Field Measurement 74.66 74.7 If you have any questions in regards to the above, please do not hesitate to contact this office. Very Truly Yours, PASCO ENGINEERING, INC. LAND SG9 oe Yuhas L. S. LS 5211 Exp. 06/30/07 P OF CALL aM S V 0 v Geotechnical Ge+b16g i sEnviro mental 5741 Palmer Way Carlsbad, California 92008 • (760) 438 -3155 FAX (760) 931 -0915 September 28, 2004 W.O. 4306-A3-SC Mr. Tim Clancy P.O. Box 358 Cardiff, California 92007 Subject: Second Response to EsGil Corporation Comments, Plan Check No. 04-1181/2, 2145 Manchester Avenue, Encinitas, San Diego County, California References: 1. "Structural Plans for Casitas By The Sea," Sheets S -1, SN -2, SD -4, and D -2, Job #200134R, Print dated September 7, 2004, by DZN Partners Architecture. 2. "Preliminary Geotechnical Evaluation, 2145 Manchester Avenue, City of Encinitas, San Diego County, California," W.O.4306 -A -SC, dated April 30, 2004, by GeoSoils, Inc. Dear Mr. Clancy: GeoSoils, Inc. (GSI) has prepared this second response to the review of EsGil Corporation Plan Review Comments, Plan Check No. 04-1181/2, 2145 Manchester Avenue, in Encinitas, San Diego County, California. For ease of review, the reviewer's comments are repeated below, followed by GSI's response to the comments. The recommendations contained in the referenced reports (see above References) should be properly incorporated into design and construction of the subject site, except as specifically superceded by the site and construction specific recommendations presented in the following paragraphs. The recommendations provided herein should not be considered complete unless the referenced report is reviewed in conjunction with this response report. REVIEW RESPONSES For convenience, each review comment is presented in bold type and our response follows each comment. Comment Number 12: Provide a letter from the soils engineer confirming that the foundation plan, grading plan and specifications have been reviewed and that it has been determined that the recommendations in the soils report are properly incorporated into the construction documents. Response to Comment Number 12: The foundation plans by DZN Partners Architecture (see Reference No. 1), have been reviewed by this office and appear to be in general conformance with the recommendations provided by this office and presented in the referenced report by GSI, from a geotechnical viewpoint. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops, or conditions exposed, during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty is expressed or implied. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. The opportunity to be of service is greatly appreciated. If you have any questions, please do not hesitate to call our office.�� Respectfully su GeoSoils, In V0. Fu /2-O o n P. Franklin Or Cr��" David W. Skelly ngineering Geologist, CEG 1340 Civil Engineer, RC 47857 BEV /JPF /DWS /jk Distribution: (2) Addressee (2) DZN Partners Architecture; Attention, Mr. Bart M. Smith Mr. Tim Clancy W.O. 4306 -A3 -SC 2145 Manchester Avenue, Encinitas September 28, 2004 Fi1e:e:\wp9 \4300 \4306a3.srt Page 2 GeoSoils, Inc. S 9 . Geotechnical - Geologic - Environmental 5741 Palmer Way - Carlsbad, California 92008 - (760) 438 -3155 - FAX (760) 931 -0915 September 27, 2004 W.O. 4306-A2-SC Mr. Tim Clancy P.O. Box 358 Cardiff, California 92007 Subject: Response to Geopacifica, Inc., Third Party Review, Drawing #9087 -G, Planning Case No. 02 -014 V /DR /CDP, 2145 Manchester Avenue, Encinitas, San Diego County, California Dear Mr. Clancy: In accordance with your authorization, GeoSoils, Inc. (GSI) has prepared this response to the Geopacifica Inc. Third party Review, Drawing #9087 -G, Planning Case No. 02 -014 V /DR /CDP, 2145 Manchester Avenue, Encinitas, San Diego County, California. For ease of review, the reviewers comments are repeated below, followed by GSI's response to the comments. The recommendations contained in the referenced reports (see the Appendix) should be properly incorporated into design and construction of the subject site, except as specifically superceded by the site and construction specific recommendations presented in the following paragraphs. The recommendations provided herein should not be considered complete unless the referenced reports (see the Appendix) are reviewed in conjunction with this response. REVIEW RESPONSE For convenience, each review comment is presented in bold type and our response follows each comment. Comment Number 1: Based on a review of the submitted documents, it does not appear as if the geotechnical consultant of document 1 has seen or reviewed document 2. The geotechnical report document 1 provides on page 33 for geotechnical review of plans. In addition, the report provides "based on our review, supplemental recommendations and /or further geotechnical studies may be warranted." Response to Comment Number 1: The grading plans, notes, and details have been reviewed by this office and appear to be in general conformance with the recommendations provided by this office and presented in the referenced reports by GSI (see the Appendix), from a geotechnical viewpoint. Based on our review, the following comments are provided: • Based on GSI's review of the current grading plan by Pasco Engineering, Inc., (Pasco, 2004), a planned transition and /or maximum to minimum fill thickness below a given structure may exceed 3:1. Overexcavation should be completed to reduce this ratio to 3:1, or less, below the entire structure, including garage sub - floor. Once the depth dimension of the pool is given by the project design civil engineer, the maximum to minimum fill thickness may be analyzed, and appropriate recommendations provided. Comment Number 2: A geotechnical review of document 2 is required to be performed by the geotechnical consultant for this project. In addition to the normal review procedure the consultant should also address the items listed below. Response to Comment Number 2: Acknowledged; see above and below. Comment Number 3: The maximum depth of exploration 4 feet. The document 1 provides (page 1) the garage portion of the sub floor will be 4 feet below grade so that foundations will be deeper than 4 feet. Please clarify why exploration did not extend to a depth of proposed foundation plus 5 feet. Response to Comment Number 3: At the time of GSI's field investigation, grading plans were not available. However, based on exposures and similar jobs within the vicinity, and in light of the pervasive nature of site geologic unit, it is GSI's opinion that the soil conditions at 4 feet generally represent the soil condition ±5 to ±6 feet deep in the basement area. In addition, the geotechnical review of the current grading plans (Pasco, 2004) indicate atransition within the planned building footprint, therefore the cut portion of the pad, including the garage sub - floor, should be overexcavated a minimum 3 feet below pad grade. Where the ratio of maximum to minimum fill thickness below a given structure exceeds 3:1, overexcavation should be completed to reduce this ratio to 3:1, or less. Mr. Tim Clancy W.O. 4306 -A2 -SC 2145 Manchester Avenue, Encinitas September 27, 2004 Fi1e:eAwp9 \4300 \4306a2Ap Page 2 GeoSoils, Inc. Comment Number 4: The logs of exploration do not list any soil samples collected. A soil sample is listed as tested for maximum density /optimum moisture, expansion index, and direct shear. Please clarify why soil samples are not listed on the logs. Also note that boring log B -4 does not identify soil from 1 1 /2 to 4 feet. Are these soils "Colluvium/Topsoil "? Please clarify as necessary. Response to Comment Number 4: GSI apologizes for any inconvenience owing to the typographical errors on the boring logs. A bulk sample was taken from Boring B -1 from 0 to 4 feet, and was utilized in our laboratory studies. Boring Log B -4 should indicate terrace deposits from 1'/2 to 4 feet. Comment Number 5: The report 1 provides on page 9 "laboratory test results for soluble sulfates, pH, and corrosion to metals have not been received as of the date of this report." Please provide the results of such testing. Response to Comment Number 5: GSI has provided the soil corrosivity results dated May 10, 2004. A copy of this document has been provided for the reviewer. Comment Number 6: The document 1 provides guidelines for special handling of an existing pool. Please provide specific recommendations relative to the proposed plans depicted as document 2. Response to Comment Number 6: The current grading plans (Pasco, 2004) indicate that settlement- sensitive improvements are proposed in the pool area. Therefore, as indicated in the GSI report (GSI, 2O04b), the pool shell should be completely removed and replaced with properly compacted fill. Comment Number 7: Please provide the depth dimensions of the pool and soil types that underlie the pool. Will backfill of the pool excavation create a potential for differential settlement? Mr. Tim Clancy W.O. 4306 -A2 -SC 2145 Manchester Avenue, Encinitas September 27, 2004 File:e:\wp9 \4300 \4306a2Ap Page 3 GeoSoils, Inc. Response to Comment Number 7: It is GSI's opinion that the design civil engineer should provide the depth dimensions of the pool. Soil types that underlie the pool are reasonably anticipated to be sandy sediments belong to the terrace deposits. During grading, this condition will be further evaluated and removals of compressible and /or unsuitable bearing soil materials will be conducted prior to the placement of fill. As indicated in GSI (2004b), where the ratio of maximum to minimum fill thickness below a given structure exceeds 3:1, overexcavation should be completed to reduce this ratio to 3:1; or less, across the entire structure. Comment Number 8: Please address the potential of impact to adjacent properties during site construction and provide specific mitigation recommendations to avoid impact to the adjacent properties. Response to Comment Number 8: It should be noted, that the Uniform Building Code /California Building Code ([UBC /CBC], International Conference of Building Officials [ICBO],1997 and 2001) specifically requires that removals of unsuitable soils be performed across all areas to be graded, not just within the influence of the residential structure. Relatively deep removals may also necessitate a special zone of consideration, on perimeter /confining areas. This zone would be approximately equal to the depth of removals, if removals cannot be performed offsite. Thus, any settlement- sensitive improvements (walls, curbs, flatwork, etc.), constructed within this zone, may require deepened foundations, reinforcement, etc., or will retain some potential for settlement and associated distress. This will require proper disclosure to all homeowners and any homeowner association. A review of the current grading plans (Pasco, 2004) indicate a retaining wall along the north, east, and south boundaries of the property line. As discussed above, perimeter /confining areas exist with respect to removals within the currently planned locations. Complete removals may or may not be accomplished where influenced by the existing retaining wall. This zone may require deepened foundations, reinforcement, etc., or other alternatives, such as shoring, may be required. As indicated in GSI (2004b), preliminary shoring recommendations were provided. The ultimate embedment depth should be provided by the project structural engineer and /or shoring designer, based on the supplemental geotechnical parameters reiterated below: Mr. Tim Clancy W.O. 4306 -A2 -SC 2145 Manchester Avenue, Encinitas September 27, 2004 Fi1e:e:\wp9 \4300 \4306a2.rtp Page 4 GeoSoils, Inc. General Should insufficient space for constructing portions of the proposed residence be encountered, shoring may be required. Shoring should consist of cantilever steel soldier beams placed at a maximum of 6 -foot on centers, with a minimum embedment below the bottom of the cut, equivalent to half the height of the cut. The ultimate embedment depth should be provided by the project structural engineer and /or shoring designer, based on the geotechnical parameters provided herein. Wood lagging should be installed as the cut progresses to its ultimate configuration. Lateral Pressures For design on cantilevered shoring, atriangular distribution of lateral earth pressure may be used. It may be assumed that the retained soils, with a level surface behind the shoring, will exert a lateral pressure equal to that developed by a fluid with a density of 40 pounds per cubic foot (pcf). Retained soils with a 2:1 back slope ratio will exert a lateral pressure equal to a fluid with a density of 60 pcf. If street traffic is located within 10 feet of shorings, the upper 10 feet of shoring adjacent to the traffic should be designed to resist a uniform lateral pressure of 100 pounds per square foot (psf), which is a result of an assumed 300 psf surcharge behind the shoring due to normal street traffic. Design of Soldier Piles For the design of soldier piles spaced at least 2 diameters on centers, the allowable lateral bearing value (passive value) of the soils below the level of excavation may be assumed to be 500 psf per foot of depth, up to a maximum of 5,000 psf. To develop the full lateral value, provisions should be taken to assure firm contact between the soldier piles and the undisturbed soils. The soldier piles below the excavated levels may be used to resist downward loads, if any. The downward frictional resistance between the soldier piles and the soils below the excavated level may be taken as equal to 300 psf. Lagging Continuous wood lagging will be required between the soldier piles. The soldier piles should be designed for the full anticipated lateral pressure. However, the pressure on the lagging will be less due to arching in the soils. We recommend that the lagging be designed for the recommended earth pressure, but limited to a maximum value of 500 psf. Mr. Tim Clancy W.O. 4306 -A2 -SC 2145 Manchester Avenue, Encinitas September 27, 2004 Fi1e:eAwp9 \4300 \4306a2Ap Page 5 GeoSoils, Inc. Internal Bracing Rakers may be required to internally brace the soldier piles. The raker bracing could be supported laterally by temporary concrete footings (deadmen), or by the permanent interior footings. For design of temporary footings, ordeadmen, poured with the bearing surface normal to rakers inclined at 45 degrees, a bearing value of 2,500 psf may be used, provided the shallowest point of the footing is at least 1 foot below the lowest adjacent grade. Deflection It is difficult to accurately predict the amount of deflection of a shored profile. It should be realized, however, that some deflection will occur. We anticipate that this deflection would be on the order of inch at the top of the planned 10- to 12 -foot shoring. If greater deflection occurs during construction, additional bracing may be necessary to minimize deflection. If desired to reduce the deflection of the shoring, a greater active pressure, leading to a more stiffer section, could be used. Monitoring Some means of monitoring the performance of the shoring system is recommended. The monitoring should consist of periodic surveying of the lateral and vertical locations of the tops of all the soldier piles, and the lateral movement along the entire lengths of selected soldier piles. We suggest that photographs of the adjacent improvements be made prior to excavation. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and /or testing be performed by GSI at each of the following construction stages: • During grading /recertification. • During any excavation. • During placement of subdrains, toe drains, or other subdrainage devices, prior to placing fill and /or backfill. • After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Mr. Tim Clancy W.O. 4306 -A2 -SC 2145 Manchester Avenue, Encinitas September 27, 2004 Fi1e:e:\wp9 \4300 \4306a2.rtp Page 6 GeoSoils, Inc. • Prior to pouring any slabs or flatwork, after presoaking /presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea - gravel, etc.), or vapor barriers (i.e., visqueen, etc.). • During retaining wall subdrain installation, prior to backfill placement. • During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. • During slope construction /repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. • When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed. • A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and /or to comply with code requirements. CLOSURE The conclusions and recommendations presented herein are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty is expressed or implied. Standards of practice are subject to change with time. GSI assumes no responsibility for work, testing, or recommendations performed or provided by others. Mr. Tim Clancy W.O. 4306 -A2 -SC 2145 Manchester Avenue, Encinitas September 27, 2004 Fi1e:e:\wp9 \4300 \4306a2.np Page 7 GeoSoiils, Inc. The opportunity to be of service is greatly appreciated. If you have any questions, please do not hesitate to call our office. Respectfully submitted, GeoSoils, Inc. V s Bryan oss �, .:.' �'ti�J v Project Geologist Fk fo p. : a i::31 d HO. 1340 a S f1 D,,p noo.6n$ �` ' David W. Ske I . cl � iu John P. ranklin ,� <.�•• y ��`� ' t Civil Engineer, RCE 4 �'^ ��, Engineering Geologis , C pt p g BEV /JPF /DWS /jk /jh Attachment: Appendix - References Distribution: (2) Addressee (1) Pasco Engineering, Attention: Mr. John Connolly (1) Geopacifica, Inc., Attention: Mr. Ernie Artim Mr. Tim Clancy W.O. 4306 -A2 -SC 2145 Manchester Avenue, Encinitas September 27, 2004 Fi1e:eAwp9 \4300 \4306a2Ap Page 8 GeoSoils, Inc. APPENDIX REFERENCES Geopacifica Inc., 2004, Review memorandum, Third party review, Drawing #9087 -G, Planning case no. 02 -014 V /DR /CDF, 2145 Manchester Avenue, APN: 261 062 04 00, Encinitas, dated August 27. GeoSoils, Inc., 2004a, Soil corrosivity results, 2145 Manchester Avenue, City of Encinitas, San Diego County, California, W.O.4306 -A -SC, dated May 10. 2004b, Preliminary geotechnical evaluation, 2145 Manchester Avenue, City of Encinitas, San Diego County, California, W.O.4306 -A -SC, dated April 30. International Conference of Building Officials, 2001, California building code, California code of regulations title 24, part 2, volume 1 and 2. 1997, Uniform building code. Pasco Engineering, 2004, Grading and erosion control plan for: Casitas by the Sea, 2145 Manchester Avenue, Cardiff, CA., APN # 261- 052- 04 -00, Sheet 1 and 2, Drawing no. 9087 -G, dated September 20. GeoSoils, Inc. S 9 . Geotechnical *Geologic- Environmental 5741 Palmer Way • Carlsbad, California 92008 • (760) 438 -3155 • FAX (760) 931 -0915 May 10, 2004 W.O.4306 -A -SC Mr. Tim Clancy P.O. Box 358 Cardiff, California 92007 Subject: Soil Corrosivity Results, 2145 Manchester Avenue, City of Encinitas, San Diego County, California References: 1. "Preliminary Geotechnical Evaluation, 2145 Manchester Avenue, City of Encinitas, San Diego County, California," W.0.4306 -A -SC, dated April 23, 2004, by GeoSoils, Inc. 2. "Uniform Building Code," Whittier, California, Vol. 1, 2, and 3, dated 1997, by International Conference of Building Officials. Dear Mr. Clancy: As discussed in Reference No. 1, GeoSoils, Inc. (GSI) conducted sampling of representative soils on the subject site for corrosivity. Laboratory test results were completed by M.J. Schiff (consulting corrosion engineers). Unless specifically superceded herein, the conclusions and recommendations contained in the referenced report by GSI remain pertinent and applicable, and should be appropriately implemented during design and construction. SUMMARY Atypical sample of the site materials was analyzed for corrosion /acidity potential (attached as Figure 1, following the text of this letter). The testing included determination of soluble sulfates, pH, and saturated resistivity. Results are as follows: site soils are generally neutral (pH of 7.3), are corrosive to metals (i.e., 1,700 ohms -cm), and have a negligible potential for sulfate exposure to concrete (i.e., 0.03 soluble sulfate percent by weight in soil). Alternative methods and additional comments regarding foundations, piping, etc., should be obtained from a qualified corrosion engineer. We appreciate the opportunity to be of further service. If you should have any questions, please do not hesitate to call our office. _.. Respectfully submitted GeoSoils, Inc. Reviewed by ; y� !a' ��L s� NO 1340 C t d a' c c+'.R t enginleering . Franklin F� David W. Skelly Geologist, C Civil Engineer, RCE 47857 DG /JPF /DWS /jk Attachment: Figure 1 - Corrosion Test Results Distribution: (4) Addressee Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue, Encinitas May 10, 2004 File:eAwp9 \4300 \4306a.scr Page 2 GeoSoils, Inc. M. I Schiff & Associates, Inc Consulting Corrosion Engineers - Since 1959 Phone. (909) 62696967 Fax. (909) 626-331 431 W. Baseline Road Fmail lah@mjschiff. calm Claremont, CA 91711 Website: mischiff.co Table I - Laboratory Tests on Soil Samples Clancy Your #4036 -A-SC, MJS&A #04-0584f-4B 27-Apr-04 Sample ID B-1 ... . . .......... a0.4' Resistivity Units as-received ohm-cm 60,000 saturated ohm-cm 1,700 pH 7.3 Electrical Conductivity ms/cm 0.36 Chemical Analyses Cations calcium Ca 2+ Mg/kg 228 magnesium M.g mg/kg 36 sodium Na mg/kg I Anions carbonate CO, mg/kg ND bicarbonate HCO mg/kg 330 chloride C11- mg/kg 110 sulfate so, 2- mg/kg 286 Other Tests ammonium NH4 I+ mg/kg na tutratc NQ mg/kg no sulfide sz- qua] na Redox mv na T'771�7 Electrical conductivity in millisjemen.Vcm and chemical analysis were made on a 1:5 soil-to-water extract, mg/kg = milligrams per kilogram (parts per million) of dry soil. Redox = oxidation-reduction potential in millivolts ND - not detected na = not analyzed W.O. 4306-A-SC Page I of 1 Figure f JAN 1 8 2005 L� s, 0 Geotechn cal • GOWNC1C�'a al 5741 Palmer Way Carlsbad, California 92008 • (760) 438 -3155 • FAX (760) 931 -0915 May 10, 2004 W.O.4306 -A -SC Mr. Tim Clancy P.O. Box 358 Cardiff, California 92007 Subject: Soil Corrosivity Results, 2145 Manchester Avenue, City of Encinitas, San Diego County, California References: 1. "Preliminary Geotechnical Evaluation, 2145 Manchester Avenue, City of Encinitas, San Diego County, California," W.0.4306 -A -SC, dated April 23, 2004, by GeoSoils, Inc. 2. "Uniform Building Code," Whittier, California, Vol. 1, 2, and 3, dated 1997, by International Conference of Building Officials. Dear Mr. Clancy: As discussed in Reference No. 1, GeoSoils, Inc. (GSI) conducted sampling of representative soils on the subject site for corrosivity. Laboratory test results were completed by M.J. Schiff (consulting corrosion engineers). Unless specifically superceded herein, the conclusions and recommendations contained in the referenced report by GSI remain pertinent and applicable, and should be appropriately implemented during design and construction. SUMMARY Atypical sample of the site materials was analyzed for corrosion /acidity potential (attached as Figure 1, following the text of this letter). The testing included determination of soluble sulfates, pH, and saturated resistivity. Results are as follows: site soils are generally neutral (pH of 7.3), are corrosive to metals (i.e., 1,700 ohms -cm), and have a negligible potential for sulfate exposure to concrete (i.e., 0.03 soluble sulfate percent by weight in soil). Alternative methods and additional comments regarding foundations, piping, etc., should be obtained from a qualified corrosion engineer. • We appreciate the opportunity to be of further service. If you should have any questions, please do not hesitate to call our office. Respectfully submitted ��R`D Gc, Fi%q !0 `r , GeoSoils, Inc. ;� Ia <�, �,, Reviewed by: e NO. 1340 ohn P. Franklin F��© David W. Skelly ngineering Geologist, C Civil Engineer, RCE 47857 DG /JPF /DWS /jk Attachment: Figure 1 - Corrosion Test Results Distribution: (4) Addressee Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue, Encinitas May 10, 2004 Fi1e:eAwp9 \4300 \4306a.scr Page 2 GeoSoils, Inc. M. I Schiff & Ass ociates, Inc. Consulting Corrosion Engin - Since 1959 Phone: (909) 626 -0967 Fax: (909) 626-3316 431 W. Baseline Road F, -mail Iab@mjscIsiff.com Claremont, CA 91717 websire: mischiff.com Table I - Laboratory Tests on Soil Samples Clancy Your #4036 -A-SC, MJS&A 404-05841 „4A 27- Apr -04 Sample ID B-1 .. . . .......... Resistivity Units as-received ohm-cm 60,000 saturated ohm-cm 1,700 PH 7.3 Electrical Conductivity MS/cm 0.36 Chemical Analyses Cations calcium Ca 2... mg/kg 228 magnesium Mg” mg/kg 36 sodium Na I+ mg/kg I Anions. carbonate CO3 2- Mg/kg ND bicarbonate HCO mg/kg 330 chloride C11- mg/kg 110 sulfate SO4 2- mg/kg 286 Other Tests ammonium NH4 I+ mg/kg na nitrate NO.,' me/kg no sulfide s2- qua] na Redox mV na 7 Electrical conductivity in m illi s i emen g .1cm and chemical analysis were made on a 1:5 Soil-to-water extract. mg/kg = milligrams per kilogram (parts per million) of dry soil. Redox = oxidation-reduction potential in millivolts ND - not detected na = not analyzed W.O. 4306-A-SC Page I of I Figure 1 GeoSoils, Inc. PASCO ENGINEERING, INC. 535 NORTH HIGHWAY 101, SUITE A SOLANA BEACH, CA 92075 (858) 259 -8212 WAYNE A. PASCO FAX (858) 259 -4812 R.C.E. 29577 HYDROLOGY STUDY for Casitas By The Sea 2145 Manchester Ave City of Encinitas, CA PREPARED FOR: Tim Clancy and Colleen Pitts PO Box 358 Cardiff, Ca 92007 DATE: July 5, 2004 Revised August 12, 2004 O N/ a' Fi f { WAYNE A. PASCO, RCE 29577 DATE HYDROLOGY STUDY for Casitas By The Sea PE 1276 TABLE OF CONTENTS SECTION Executive Summary 1.0 Introduction 1.1 Existing Conditions 1.2 Proposed Project 1.3 Summary of Results and Conditions 1.4 Conclusions and Conditions of Concern 1.5 References 1.6 Methodology 2.0 Introduction 2.1 County of San Diego Criteria 2.2 City of San Diego Standards 2.3 Runoff coefficient determination 2.4 Hydrology Model Output 3.0 Pre - Developed Hydrologic Model Output 3.1 Post - Developed Hydrologic Model Output 3.2 Rational Method Spreadsheet Analysis of Offsite Area 3.3 Hydraulic Analysis and Curb Inlet Sizing 4.0 Hydraulic Analysis of Proposed Storm Drain Pipe 4.1 Pump Sizing 4.2 Storm Water Quality and BMPs 5.0 Comparison of existing and post - developed conditions 5.1 BMPs to address storm water quality goals 5.2 Existing and Post - Developed Condition Hydrology Map (pocket) \\Serveryob files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7/7/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 1.0 EXECUTIVE SUMMARY 1.1 Introduction This Hydrology Study for Casitas By The Sea proposed development located at 2145 Manchester Ave has been prepared to analyze the hydrologic and hydraulic characteristics of the existing and proposed project site. This report intends to present both the methodology and the calculations used for determining the runoff from the project site in both the pre - developed (existing) conditions and the post - developed (proposed) conditions produced by the 100 year 6 hour storm. In addition this report will propose the sizing of all necessary storm drain facilities and storm drain piping necessary for the storm drain system to safely convey the runoff from the 100 -year rainfall event. 1.2 Existing Conditions The property is geographically located in the City of Encinitas, more specifically at 2145 Manchester Avenue in Cardiff. The site is surrounded by both existing and recent residential development. The project site is roughly located east of Pacific Coast Highway 101 and west of Interstate 5. The project site is located along the easterly side of Manchester Avenue, south of Liverpool Drive, and north of Chesterfield Drive, as shown on the vicinity map below. q M - D m x �CIFIC OCEAN ~^ /C } m ., S \\Server\job files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 127612:47 PM 7/7/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 The existing project site consists of two parcels which have been developed into a single - family residence. Drainage from the existing site is primarily conveyed in a southwesterly direction across the project site. The backyard currently has below ground pool and the remaining area is a improved with a slate and concrete patio. In addition to the storm water generated on -site, periodically storm water from the southerly neighbor's property and from the public alley to the east of the project site overtops an existing retaining. It should be noted that the existing alley way to the east of the project site is a significant drainage issue, and contributes to flooding problems in the project area vicinity. The alley is a problem because storm water collected in the alley has no method of draining presently, with the exception of ponding and sheet flowing to the west through the existing apartment complex to the south of the project site and also, to a lesser extent through the project site. With additional future development combined with the recent improvements to the alley, which include full -width paving and a 3 -foot ribbon gutter in the center of the alley, storm water volume collected in the alley may increase and could pose a potential problem in terms increased flooding potential. With a greater risk of flooding, the structural integrity of the existing apartment complex to the south of the project site and the retaining walls located along the westerly side of the alley way including the existing retaining wall located on the project site. 1.3 Proposed Project The intent of project is to develop the project site into two attached single - family dwellings, a twin home. The proposed development consists of the grading to create a basement and a suitable pad for construction, construction of two retaining walls adjacent to the driveway in order to provide a level walk way for access to the main entry ways of each residence and to the backyard, and the construction of the attached twin home. The existing slate patio and pool will be removed and filled in to create a grass or landscaped backyard. Drainage of the proposed project will be addressed primarily through the construction of two area drain systems. Each lot will have its own storm drain system, which will consist of an area drain system as well as a 16 -foot trench frame and grate inlet, and an 18 -inch CB to collect storm water from the driveway. A pump system will discharge the water from the trench grate up to the protected landscape area before sheet flowing through the landscaping and ultimately into Manchester Ave. Where possible, including the runoff collected in the driveway, all storm water will be conveyed through a grassy biofilters swale, which is intended to act as a storm water cleansing mechanism. In addition to the biofilters swales, a significant area of impervious surface will be recovered with the development of the proposed project. Other BMPs, including source control and site design are discussed in section 5.0 of this report. \\Server\job files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 4:16 PM 8/12/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 1.4 Summary of Results Upon performing hydrologic analysis of the project site in both the proposed developed and existing condition the following results were produced. In existing conditions the hydrologic model included the analysis of the project site at one point of discharge. Output data from the hydrologic analysis model of the project site in the existing condition indicates that the 100 -year peak runoff flow of 0.59 cfs is generated by the project site. The total area of the existing project site contributing storm water runoff is equal to 0.12 acres. The output data, from the hydrologic analysis model of the proposed project, indicates that the 100 -year peak flow for each lot is equal to 0.26 cfs for a total of 0.52 cfs. The total area of the proposed project is equal to 0.12 acres; of which 0.06 acres is associated with the northerly lot and residence, and 0.06 acres is associated with the southerly lot and residence 1.5 Conclusions and Conditions of Concern The proposed development will actually reduce the amount of runoff from the project site as compared to the runoff from the site in the existing conditions. Due to the impact of the of the impervious surface in the backyard of the existing residence, and the subsequent recovery of pervious area as result of the proposed construction there is a minor decrease in the storm water peak flow rate from the project site. To further illustrate this, the table below breaks down the pre - developed and post - developed runoff flows. COMPARISON OF PRE - DEVELOPED & POST - DEVELOPED CONDITIONS PRE - DEVELOPED POST - DEVELOPED NODE AREA Tc FLOW NODE AREA Tc FLOW (NUMBER) (ACRES) (MIN) (CFS) (NUMBER ACRES) (MIN (CFS 11 0.07 6.0 0.38 12 0.06 6.5 0.26 12 0.05 6.4 0.21 22 0.06 6.4 0.26 TOTALS PRE - DEVELOPED: 0.12 ACRES 0.59 CFS POST - DEVELOPED 0.12 ACRES 0.52 CFS RUNOFF FLOW INCREASE 0.07 CFS The proposed storm drain system incorporates the design of two area drain systems. Each system will be required to handle a capacity of 0.26 cfs, and the hydraulic analysis of the 4 -inch pvc area drain pipe at a slope of 1 % will have the capacity to convey 0.27 cfs when completely full and a maximum of 0.30 cfs. \ \Serveryob files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7/7/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 The pumps sized for the proposed trench grate inlets will be required to pump 0.05 cfs with a head of 4.54 feet. In addition to the above requirements, the following discusses the conditions of concern which the City of Encinitas should be aware of- 1 Manchester Avenue in the location of the project site is not a standard road. The ROW width, in particular the distance between the curbline and the property line roughly 4.5 feet, which is an insufficient length to construct a standard driveway apron or construct a standard sidewalk. In addition to an inadequate ROW width, the road does not have a standard curb and gutter, but rather a PCC berm which fluctuates in height. In addition the crown of the street meanders and the cross slope is not consistent. 2 The Public Alley Way to the east of the proposed project is a significant drainage concern. A low point, a sump situation exists to the south of the proposed project site. Residences in the area have identified that this area is subject to frequent flooding during rainfall events. The only drainage path for this water presently, is through the apartment complex site to the south of the project site. The drainage path is insufficient to convey the entire flow from any significant rainfall event. With the recent improvements to the alley to the north, of the project site, which included full width paving and a 3 -foot ribbon gutter, and the discharge of existing residential developments to the alley way, storm water is now concentrated and conveyed faster to the low point of the alley way. Particular attention should be paid to this situation with regards to future re- development and development of property proposing to discharge storm water to the alley way. Since significant retaining wall and structures that have driveways sloping down to the building exist along the alley way, there is a potential for flooding occurrences to impact the integrity of these structures. 2.1 References "San Diego County Hydrology Manual, revised June 2003, County of San Diego, Department of Public Works, Flood Control Section. "Drainage Design Manual ", City of San Diego, April 1984, addendum March 1989. "Grading, Erosion and Sediment Control Ordinance /Chapter; City of Encinitas, Engineering Services and Community Development Department, revised November 2002. \ \Serveryob files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7/7/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 2.0 METHODOLOGY 2.1 Introduction The hydrologic model used to perform the hydrologic analysis presented in this report utilizes the Ration Method (RM) equation, Q =CIA. The RM formula estimates the peak rate of runoff based on the variables of area, runoff coefficient, and rainfall intensity. The rainfall intensity (1) is equal to: 1 = 7.44 x P6 x D -0.645 Where: I = Intensity (in /hr) P6 = 6 -hour precipitation (inches) D = duration (minutes — use Tc) Using the Time of Concentration (Tc), which is the time required for a given element of water that originates at the most remote point of the basin being analyzed to reach the point at which the runoff from the basin is being analyzed. The RM equation determines the storm water runoff rate (Q) for a given basin in terms of flow (typically in cubic feet per second (cfs) but sometimes as gallons per minute (gpm)). The RM equation is as follows: Q =CIA Where: Q= flow (in cfs) C = runoff coefficient, ratio of rainfall that produces storm water runoff (runoff vs. infiltration /evaporation /absorption /etc) I = average rainfall intensity for a duration equal to the Tc for the area, in inches per hour. A = drainage area contributing to the basin in acres. The RM equation assumes that the storm event being analyzed delivers precipitation to the entire basin uniformly, and therefore the peak discharge rate will occur when a raindrop that falls at the most remote portion of the basin arrives at the point of analysis. The RM also assumes that the fraction of rainfall that becomes runoff or the runoff coefficient C is not affected by the storm intensity, I, or the precipitation zone number. In addition to the above Ration Method assumptions, the conservative assumption that all runoff coefficients utilized for this report are based on type "D" soils. 2.2 County of San Diego Criteria As defined by the County Hydrology Manual dated June 2003, the rational method is the preferred equation for determining the hydrologic characteristics of \ \Serveryob files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7/7/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 basins up to approximately one square mile in size. The County of San Diego has developed its own tables, nomographs, and methodologies for analyzing storm water runoff for areas within the county. The County has also developed precipitation isopluvial contour maps that show even lines of rainfall anticipated from a given storm event (i.e. 100 -year, 6 -hour storm). One of the variables of the RM equation is the runoff coefficient, C. The runoff coefficient is dependent only upon land use and soil type and the County of San Diego has developed a table of Runoff Coefficients for Urban Areas to be applied to basin located within the County of San Diego. The table categorizes the land use, the associated development density (dwelling units per acre) and the percentage of impervious area. Each of the categories listed has an associated runoff coefficient, C, for each soil type class. The County has also illustrated in detail the methodology for determining the time of concentration, in particular the initial time of concentration. The County has adopted the Federal Aviation Agency's (FAA) overland time of flow equation. This equation essentially limits the flow path length for the initial time of concentration to lengths of 100 feet or less, and is dependent on land use and slope. 2.3 City of Encinitas Standards The City of Encinitas has additional requirements for hydrology reports which are outlined in the Grading, Erosion and Sediment Control Ordinance. Please refer to this manual for further details. 2.4 Runoff Coefficient Determination As stated in section 2.2, the runoff coefficient is dependent only upon land use and soil type and the County of San Diego has developed a table of Runoff Coefficients for Urban Areas to be applied to basin located within the County of San Diego. The table on the following page categorizes the land use, the associated development density (dwelling units per acre) and the percentage of impervious area. For the proposed development the total number of dwellings proposed is two, and the total lot area is equal to 0.11 acres. This corresponds to a dwelling unit per acre (DU /A) ratio of 17.42. Therefore the runoff coefficient of 0.71, which corresponds to DU /A of 24.0 or less and an impervious ration of 65% was chosen. For the existing conditions, runoff coefficients were selected based upon impervious ratios and (DU /A) ratio. \ \Server\job files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7/7!2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 3.0 HYDROLOGY MODEL OUTPUT 3.1 Pre - Developed Hydrologic Model Output RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2001,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982 -2002 Advanced Engineering Software (aes) Ver. 1.5A Release Date: 01/01/2002 License ID 1452 Analysis prepared by: Pasco Engineering, Inc. 535 North Highway 101, Suite A Solana Beach, CA 92075 858- 259 -8212 phone 858- 259 -4812 fax + + + + + + + + + + + + + + + + + + + + + + + + ++ DESCRIPTION OF STUDY + + + + + + + + + + + + + + + + + + + + + + + + ++ * HYDROLOGIC ANALYSIS OF 100 -YEAR STORM EVENT FOR THE EXISTING CONDITIONS * OF THE EXISTING SINGLE FAMILY RESIDENCE LOCATED AT 2145 MANCHESTER AVE * PE 1276 FILE NAME: C: \AES- DATA \1276 \100 EX.DAT TIME /DATE OF STUDY: 10:19 07/07/2004 ---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: ---------------------------------------------------------------------------- 1985 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6 -HOUR DURATION PRECIPITATION (INCHES) = 2.600 SPECIFIED MINIMUM PIPE SIZE(INCH) = 4.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 SAN DIEGO HYDROLOGY MANUAL "C "- VALUES USED FOR RATIONAL METHOD NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED *USER - DEFINED STREET- SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET- CROSSFALL: CURB GUTTER - GEOMETRIES: MANNING WIDTH CROSSFALL IN- / OUT - /PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) --- ----- --- - - - - -- ----------- - - - - -- -- 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 GLOBAL STREET FLOW -DEPTH CONSTRAINTS: 1. Relative Flow -Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top -of -Curb) 2. (Depth) *(Velocity) Constraint = 6.0 (FT *FT /S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* FLOW PROCESS FROM NODE 10.00 TO NODE 11.00 IS CODE = 21 ---------------------------------------------------------------------------- »»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS ««< *USER SPECIFIED(SUBAREA): ROAD(HARD SURFACE) COVER RUNOFF COEFFICIENT = .9000 S.C.S. CURVE NUMBER (AMC II) = 0 !NITIAL SUBAREA FLOW - LENGTH = 50.00 UPSTREAM ELEVATION = 80.72 DOWNSTREAM ELEVATION = 80.00 ELEVATION DIFFERENCE = 0.72 URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 2.254 TIME OF CONCENTRATION ASSUMED AS 6- MINUTES 100 YEAR RAINFALL INTENSITY(INCH /HOUR) = 6.090 SUBAREA RUNOFF(CFS) = 0.38 \\Server\job files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7/7/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 TOTAL AREA(ACRES) = 0.07 TOTAL RUNOFF(CFS) = 0.38 FLOW PROCESS FROM NODE 11.00 TO NODE 12.00 IS CODE = 51 ---------------------------------------------------------------------------- » »>COMPUTE TRAPEZOIDAL CHANNEL FLOW« «< » »>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT) ««< ELEVATION DATA: UPSTREAM(FEET) = 60.00 DOWNSTREAM(FEET) = 78.32 CHANNEL LENGTH THRU SUBAREA(FEET) = 70.00 CHANNEL SLOPE = 0.0240 CHANNEL BASE(FEET) = 0.50 "Z" FACTOR = 2.000 MANNING'S FACTOR = 0.022 MAXIMUM DEPTH(FEET) = 0.25 100 YEAR RAINFALL INTENSITY (INCH/ HOUR) = 5.821 *USER SPECIFIED(SUBAREA): SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .7100 S.C.S. CURVE NUMBER (AMC II) = O TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.49 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY (FEET /SEC.) = 2.68 AVERAGE FLOW DEPTH(FEET) = 0.20 TRAVEL TIME(MIN.) = 0.43 Tc(MIN.) = 6.43 SUBAREA AREA(ACRES) = 0.05 SUBAREA RUNOFF(CFS) = 0.21 TOTAL AREA(ACRES) = 0.12 PEAK FLOW RATE(CFS) = 0.59 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.22 FLOW VELOCITY(FEET /SEC.) = 2.78 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 12.00 = 120.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 0.12 TC(MIN.) = 6.43 PEAK FLOW RATE(CFS) = 0.59 END OF RATIONAL METHOD ANALYSIS \ \Serveryob files\Hydrology & Hydraulics \1276 Clancy\1276 HYD- 01.doc PE # 1276 12:47 PM 7/7/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 3.2 Post - Developed Hydrologic Model Output ++*+++++*+*+++++++*+++*++++++++++++ + + + + + + + * + + + + * + + + + + + + + + * * + + + + * ++ RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2001,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982 -2002 Advanced Engineering Software (aes) Ver. 1.5A Release Date: 01/01/2002 License ID 1452 Analysis prepared by: Pasco Engineering, Inc. 535 Ncrth Highway 101, Suite A Solana Beach, CA 92075 658- 259 -8212 phone 858 - 259 -4812 fax + * + + + + + + * + + + + + + + + + + + + + + + ++ DESCRIPTION OF STUDY + + + + + + + + + + * + + + + + + + + + + * + + ++ • HYDROLOGIC ANALYSIS OF THE 100 -YEAR PROPOSED DEVELOPED CONDITIONS FOR • CASITAS BY THE SEA, AT 2145 MANCHESTER AVENUE, CARDIFF CA • PE 1276 + FILE NAME: C: \AES- DATA \1276 \100- PRO.DAT TIME /DATE OF STUDY: 10:11 07/07/2004 ---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: ---------------------------------------------------------------------------- 1985 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6 -HOUR DURATION PRECIPITATION (INCHES) = 2.600 SPECIFIED MINIMUM PIPE SIZE(INCH) = 4.00 SPECIFIED PERCENT OF GRADIENTS (DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 SAN DIEGO HYDROLOGY MANUAL "C"- VALUES USED FOR RATIONAL METHOD NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED *USER- DEFINED STREET - SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET- CROSSFALL: CURB GUTTER - GEOMETRIES: MANNING WIDTH CROSSFALL IN- / OUT - /PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) - - - -- --- - - - - -- ------- - - - - -- - 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 GLOBAL STREET FLOW -DEPTH CONSTRAINTS: 1. Relative Flow -Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top -of -Curb) 2. (Depth) *(Velocity) Constraint = 6.0 (FT *FT /S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* +--------------------------------------------------------------------------- BEGIN ANALYSIS OF NORTHERLY LOT AND RESIDENCE I I I I +------------------------------------------------- -------------------- - - - - -+ FLOW PROCESS FROM NODE 10.00 TO NODE 11.00 IS CODE = 21 ---------------------------------------------------------------------------- »»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««< *USER SPECIFIED(SUBAREA): SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .7100 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW - LENGTH = 50.00 UPSTREAM ELEVATION = 80.70 DOWNSTREAM ELEVATION = 80.07 ELEVATION DIFFERENCE = 0.63 URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 4.596 \ \Serveryob files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7/7/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 TIME OF CONCENTRATION ASSUMED AS 6- MINUTES 100 YEAR RAINFALL INTENSITY(INCH /HOUR) = 6.090 SUBAREA RUNOFF(CFS) = 0.26 TOTAL AREA(ACRES) = 0.06 TOTAL RUNOFF(CFS) = 0.26 FLOW PROCESS FROM NODE 11.00 TO NODE 12.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE -FLOW TRAVEL TIME THRU SUBAREA««< »»>USING COMPUTER- ESTIMATED PIPESIZE (NON - PRESSURE FLOW)<<<<< ----------------------------------- ELEVATION DATA: UPSTREAM(FEET) = 79.35 DOWNSTREAM(FEET) = 78.77 FLOW LENGTH(FEET) = 95.33 MANNING'S N = 0.009 DEPTH OF FLOW IN 6.0 INCH PIPE IS 2.7 INCHES PIPE -FLOW VELOCITY(FEET /SEC.) = 2.96 ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE- FLOW(CFS) = 0.26 PIPE TRAVEL TIME(MIN.) = 0.54 Tc(MIN.) = 6.54 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 12.00 = 145.33 FEET. +--------------------------------------------------------------------- - - - - -+ I END ANALYSIS OF NORTHERLY LOT AND RESIDNECE I I BEGIN ANALYSIS OF SOUTHERLY LOT AND RESIDENCE I I +--------------------------------------------------------------------- - - - - -+ FLOW PROCESS FROM NODE 20.00 TO NODE 21.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .7100 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW- LENGTH = 50.00 UPSTREAM ELEVATION = 80.70 DOWNSTREAM ELEVATION = 80.07 ELEVATION DIFFERENCE = 0.63 URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 4.596 TIME OF CONCENTRATION ASSUMED AS 6- MINUTES 100 YEAR RAINFALL INTENSITY(INCH /HOUR) = 6.090 SUBAREA RUNOFF(CFS) = 0.26 TOTAL AREA(ACRES) = 0.06 TOTAL RUNOFF(CFS) = 0.26 FLOW PROCESS FROM NODE 21.00 TO NODE 22.00 IS CODE = 31 --------------------------------------------------------------- 7 ------------ » »>COMPUTE PIPE -FLOW TRAVEL TIME THRU SUBAREA««< »» >USING COMPUTER- ESTIMATED PIPESIZE (NON- PRESSURE FLOW) ««< ELEVATION DATA: UPSTREAM(FEET) = 79.35 DOWNSTREAM(FEET) = 78.16 FLOW LENGTH(FEET) = 95.68 MANNING'S N = 0.009 DEPTH OF FLOW IN 6.0 INCH PIPE IS 2.2 INCHES PIPE -FLOW VELOCITY(FEET /SEC.) = 3.92 ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE- FLOW(CFS) = 0.26 PIPE TRAVEL TIME(MIN.) = 0.41 TQ MIN.) = 6.41 LONGEST FLOWPATH FROM NODE 20.00 TO NODE 22.00 = 145.68 FEET. +--------------------------------------------- ------------------------ - - - - -+ I END ANALYSIS OF SOUTHERLY LOT AND RESIDENCE I I I I I +--------------------------------------------------------------------- - - -- -+ ---------------------------------------------------------------------- END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 0.06 TC(MIN.) = 6.41 PEAK FLOW RATE(CFS) = 0.26 END OF RATIONAL METHOD ANALYSIS \ \Server\job files \Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7/7/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 4.0 HYDRAULICS AND CURB INLET SIZING 4.1 Hydraulic Analysis of Proposed Storm Drain Pipe \ \Serveryob files\Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7/7/2004 4 -INCH PVC AREA DRAIN CAPACITY Worksheet for Circular Channel Project Description Project File untitied.fm2 Worksheet a Flow Element Circular Channel Method Manning's Formula Solve For Discharge Input Data Mannings Coefficient 0.009 Channel Slope 0.010000 ft/ft Depth 0.33 ft Diameter 4.00 in Results Discharge 0.29 cfs Flow Area 0.09 ft Wetted Perimeter 0.98 ft Top Width 0.07 ft Critical Depth 0.29 ft Percent Full 99.00 Critical Slope 0.009719 ft/ft Velocity 3.29 ft/s Velocity Head 0.17 ft Specific Energy 0.50 ft Froude Number 0.51 Maximum Discharge 0.30 cfs Full Flow Capacity 0.27 cfs Full Flow Slope 0.010857 ft/ft Flow is subcritical. 07/07/04 Academic Edition FlowMaster v5.17 10:59:27 AM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755 -1666 Page 1 of 1 Cross Section Cross Section for Circular Channel Project Description Project File untitled.fm2 Worksheet a Flow Element Circular Channel Method Manning's Formula Solve For Discharge Section Data Mannings Coefficient 0.009 Channel Slope 0.010000 Wit Depth 0.33 ft Diameter 4.00 in Discharge 0.29 cfs 0.33 ft 4.00 in 1� V H 1 NTS 07/07104 Academic Edition FlowMaster v5.17 10:59:38 AM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755 -1666 Page 1 of 1 HYDROLOGY STUDY for Casitas By The Sea PE 1276 4.2 Pump Sizing To adequately size a pump capable of conveying the runoff from 100 -year storm generated in the. driveway area, the maximum flow produced for this rainfall event was determined. The following illustrates the calculation for each pump: HYDROLOGIC ANALYSIS OF AREA TRIBUTARY TO EACH PUMP Q = CIA where: C = 0.95 (chosen to be conservative) = 5.78 (1= 7.44 *P6 *D^ -.645) A = 0.0099 acres (432.9 sq ft) Therefore: Q = 0.05 cfs The pumps will have to be capable of pumping the flow of 0.05 cfs with a head of 4.64 feet. \ \Serveryob files \Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 1276 12:47 PM 7!1/2004 HYDROLOGY STUDY for Casitas By The Sea PE 1276 5.0 Storm Water Quality and BMPs 5.1 Comparison of existing and post - developed conditions Although, the proposed project is not classified as a priority project, the engineer and homeowner have established water quality goals to meet through the proposed project design. The existing project site has a significant amount of impervious area in the backyard and consists of a swimming pool, and a slate patio that encompasses the entire area not occupied by the pool. Storm water in the backyard drains to an area drain system that then discharges directly to the street. The proposed project will utilize two area drain systems and the backyard will consist of pervious surfaces, and will likely include additional landscaping. This pervious area will also include several biofilters swales. 5.2 BMPs to address storm water quality goals The proposed project design, wherever possible, directs storm water across pervious landscaped and lawn areas. This site design BMP will act as a cleansing mechanism that will improve the storm water quality of the storm water being discharged from the site. Other site design BMPs include minimizing impervious surfaces. Alternatives that may be included in the design of the project site include the use of concrete wheel strips bifurcated by grass area in the driveways instead of PCC paving of the entire driveway areas; porous concrete may also be utilized in lieu of full driveway PCC paving. Porous concrete is a permeable material that permits storm water to flow through the concrete material and infiltrate into the ground. By using this material, storm water has less of an opportunity to come in contact with pollutants, suspend pollutants, and convey pollutants in its flow; and additionally the use of this material has the added benefit of reducing the runoff volume generated over the areas that have been paved with porous concrete. \ \Serveryob files \Hydrology & Hydraulics \1276 Clancy \1276 HYD- 01.doc PE # 127612:47 PM 7/7/2004 S 9 Geotechnical • Geologic • Environmental 5741 Palmer Way • Carlsbad, California 92008 • (760) 438 -3155 • FAX (760) 931 -0915 February 14, 2005 W.O. 4306 -B -SC Mr. Tim Clancy P.O. Box 358 Cardiff, California 92007 Subject: Final Compaction Report of Grading, 2145 Manchester Avenue, Encinitas, San Diego County, California References: 1. "Preliminary Geotechnical Evaluation, 2145 Manchester Avenue, City of Encinitas, San Diego County, California," W.O. 4306 -A -SC, April 30, 2004, by GeoSoils, Inc. 2. "Uniform Building Code," International Conference of Building Officials, Vol. 1, 2, and 3, Whittier, California, 1997. Dear Mr. Clancy: This report presents a summary of the geotechnical testing and observation services provided by GeoSoils, Inc. (GSI) during the rough earthwork phase of development for the new construction at the subject site. Earthwork commenced January 24, 2005, and was generally completed on February 4, 2005. Survey of line and grade and locating of the building footprint was performed by others, and not performed by GSI. The purpose of grading was to prepare a relatively level pad for the construction of two attached single - family residences. Based on the observation and testing services provided by GSI, it is our opinion that the building footprints of the proposed buildings appear suitable for their intended use. ENGINEERING GEOLOGY The geologic conditions exposed during grading were regularly observed by a representative from our firm. The geologic conditions encountered generally were as anticipated and presented in the referenced report (GSI, 2004). GEOTECHNICAL ENGINEERING Preparation of Existing Ground 1. Prior to grading, the major surficial vegetation was stripped and hauled offsite. 2. Removals consisted of topsoil /colluvium and near - surface weathered terrace deposits within the building pad area. Removals were performed to a minimum of ±3 feet outside the building footprint on the north and south sides of the building footprint, as a result of settlement- sensitive structures on adjacent property boundaries. Removals were performed to a minimum of ±5 feet outside the building footprint on the west and east sides of the building footprint. Removal depths were on the order of ±1 to ±12 feet below pre- construction grades. Once removals were completed, the exposed bottom was reprocessed, moisture conditioned, and recompacted prior to fill placement. The actual location of the proposed footprint of the building and parking lot was provided by others. Overexcavation Portions of the building pad was overexcavated in order to maintain a minimum 4 -foot thick fill blanket across the lot, for uniform conditions. Overexcavation was completed to a minimum of ±3 feet outside the building footprint on the north and south sides of the building footprint, as a result of settlement- sensitive structures on adjacent property boundaries. Overexcavation was performed to a minimum of ±5 feet outside the building footprint on the west and east sides of the building footprint. The actual location of the proposed footprint of the building was provided by others. Fill Placement Fill, consisting of native soils, was placed in 6- to 8 -inch lifts, watered, and mixed to achieve at least optimum moisture content. The fill was then compacted to 90 percent of the laboratory standard via mechanical means. The approximate limits of fill, placed under the purview of this report, are indicated on Plate 1. FIELD TESTING 1. Field density tests were performed using nuclear densometer (ASTM Test Methods D -2922 and D- 3017), and sand cone (ASTM Test Method ASTM D- 1556). The test results taken during grading are presented in the attached Table 1, and the locations of the tests taken during grading are presented on Plate 1. 2. Field density tests were taken at periodic intervals and random locations to check the compactive effort provided by the contractor. Based upon the grading Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e:\wp9 \4300 \4306bJcr Page 2 GeoSoils, Inc. operations observed, the test results presented herein are considered representative of the compacted fill. 3. Visual classification of the soils in the field was the basis for determining which maximum density value to use for a given density test. DRIVEWAY TRANSITION The driveway contains a transition between cut and fill (see Plate 1). As requested by the contractor, the driveway was not overexcavated, therefore, the transition, which occurs in the driveway, was not mitigated during grading of site. Accordingly, in order to mitigate distress, the steel reinforcement within the driveway (per plan) should be doubled (i.e., two times the number of reinforcing bars) for a distance of 10 feet horizontally past the transition, in all directions. LABORATORY TESTING Maximum Density Testing The laboratory maximum dry density and optimum moisture content for the major soil type within this construction phase were determined according to test method ASTM D -1557. The following table presents the results: MAXIMUM DENSITY I MOISTURE CONTENT SOIL TYPE" PC (PERCEN A - Reddish Brown, SILTY SAND 120.0 13.0 B - Reddish Brown, SILTY SAND 129.5 11.0 Expansion Index Expansive soil conditions have been evaluated for the site. A representative sample of the soils near pad grade was recovered for expansion index testing. Expansion Index (E.I.) testing was performed in general accordance with Standard 18 -2 of the Uniform Building Code ([UBC], International Conference of Building Officials [ICBO],1997). The test results indicate an E.I. of less than 5, and the corresponding expansion classification of very low. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 File :eAwp9 \4300 \4306b.fcr Page 3 GeoSoiils, Inc. Corrosion /Sulfate Testing Laboratory test results for soluble sulfates, pH, and corrosion to metals have not been received as of the date of this report. Testing will be presented as an addendum upon receipt of the results. CONCLUSIONS AND RECOMMENDATIONS Unless superceded by recommendations presented herein, the conclusions and recommendations contained in (GSI, 2004) remain valid and applicable, and should be properly implemented. FOUNDATION RECOMMENDATIONS General In the event that the information concerning the proposed development concept is not correct, or any changes in the design, location, or loading conditions of the proposed structure are made, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. Laboratory testing of soils exposed at finish grade indicates that the proposed foundation system will be founded into very low expansive compacted fill material. The information and recommendations presented in this section are not meant to supersede design by the project structural engineer. Upon request, GSI could provide additional input/consultation regarding soil parameters, as related to foundation design. Soil Moisture Considerations Based on conditions exposed during grading, the potential for excessive soil moisture conditions to develop beneath the floor slab is considered to be greater than that for typical slab on grade. These excessive soil moisture conditions could result in the delimitation of tile /wood flooring, condensation, and /or mold growth. In order to mitigate this potential, the following recommendations should be considered. Please be aware that the below recommendations are not a geotechnical requirement but should be implemented if the transmission of water or water vapor through the slab is undesirable. Should these recommendations not be implemented, then full disclosure of the potential for water or vapor to pass through the foundations and slabs and resultant distress, should be provided to each owner in writing. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e:\wp9 \4300 \4306bJcr Page 4 GeoSoiils, Inc. The concrete slab should be a minimum of 5 inches thick. Concrete, utilized, shall be in accordance with Table 19 -A -2 of the UBC (ICBO, 1997), for "concrete intended to have a low permeability when exposed to water" (i.e., a maximum water - cement ratio of 0.50 and a minimum strength of 4,000 psi), to mitigate the effects from post - development perched water and to impede water vapor transmission. Slab underlayment shall consist of 2 inches of washed sand placed above a vapor barrier consisting of 15 -mil polyvinal chloride, or equivalent, with all laps sealed per UBC (ICBO, 1997). The vapor barrier shall be underlain by 2 inches of pea gravel ( -' /z clean crushed rock) placed directly on the slab subgrade, and should be sealed to provided a continuos water -proof barrier underthe entire slab, as discussed above. All slabs should be additionally sealed with a suitable slab sealant. Bearing Value 1. The foundation systems should be designed and constructed in accordance with guidelines presented in the latest edition of the UBC. 2. An allowable bearing value of 2,000 pounds per square foot (psf) may be used for design of continuous footings 12 inches wide and 12 inches deep and for design of isolated pad footings 24 inches square and 24 inches deep founded entirely into compacted fill or competent formational material and connected by grade beam or tie beam in at least one direction. This value may be increased by 20 percent for each additional 12 inches in depth to a maximum value of 3,000 psf. The above values may be increased by one -third when considering short duration seismic or wind loads. No increase in bearing for footing width is recommended. Lateral Pressure 1. For lateral sliding resistance, a 0.35 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. 2. Passive earth pressure may be computed as an equivalent fluid having a density of 250 pounds per cubic foot (pcf), with a maximum earth pressure of 2,500 psf. 3. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one - third. Foundation Settlement Foundations systems should be designed to accommodate a worst case differential settlement of 1 inch in a 40 -foot span. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e: \wp9 \4300 \4306bJcr Page 5 GeoSoiils, Inc. Footing Setbacks All footings should maintain a minimum 7 -foot horizontal setback from the base of the footing to any descending slope. This distance is measured from the footing face at the bearing elevation. Footings should maintain a minimum horizontal setback of H/3 (H =slope height) from the base of the footing to the descending slope face, and no less than 7 feet nor need to be greater than 40 feet. Footings adjacent to unlined drainage swales should be deepened to a minimum of 6 inches below the invert of the adjacent unlined swale. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1:1 projection from the heel of the wall. Alternatively, walls may be designed to accommodate structural loads from buildings or appurtenances as described in the Retaining Wall section of this report. Construction The following foundation construction recommendations are presented as a minimum criteria from a soils engineering standpoint. The onsite soils expansion potentials are generally very low (E.I. 0 to 20). Recommendations for very low expansive soil conditions are presented herein. Recommendations by the project's design - structural engineer or architect, which may exceed the soils engineer's recommendations, should take precedence over the following minimum requirements. Final foundation design will be provided based on the expansion potential of the near surface soils encountered during grading. Very Low Expansion Potential (E.I. 0 to 20) 1. Exterior and interior footings should be founded at a minimum depth of 12 inches for one -story floor loads, 18 inches for two -story floor loads, and 24 inches for three -story floor loads below the lowest adjacent ground surface. Isolated column and panel pads, or wall footings, should be founded at a minimum depth of 24 inches. All footings should be reinforced with two No. 4 reinforcing bars, one placed near the top and one placed near the bottom of the footing. Footing widths should be as indicated in the UBC (ICBO, 1997); width of 12 inches for one -story loads, 15 inches for two -story loads, and 18 inches for three -story loads. 2. A grade beam, reinforced as above, and at least 12 inches wide should be provided across large (e.g., doorways) entrances. The base of the grade beam should be at the same elevation as the bottom of adjoining footings. Isolated, exterior square footings should be tied within the main foundation in at least one direction with a grade beam. 3. Residential concrete slabs, including garages, shall be in accordance with Table 19 -A -2 of the UBC (ICBO, 1997), for "concrete intended to have a low Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:eAwp9 \4300 \4306bJcr Page 6 GeoSoils, Inc. permeability when exposed to water" (i.e., a maximum water - cement ratio of 0.50 and a minimum strength of 4,000 psi), to mitigate the effects from post - development perched water and to impede water vapor transmission. Slab underlayment should consist of 2 inches of washed sand placed above a vapor barrier consisting of 15 -mil polyvinyl chloride, or equivalent, with all laps sealed per the UBC (ICBO, 1997). The vapor barrier shall be underlain by 2 inches of pea gravel ( -'/Z clean crushed rock) placed directly on the slab subgrade, and should be sealed to provide a continuous water -proof barrier under the entire slab, as discussed above. All slabs should be additionally sealed with suitable slab sealant. 4. Residential concrete slabs (including garage slabs) should be a minimum of 5 inches thick, and should be reinforced with No. 3 reinforcing bar at 18 inches on center in both directions. All slab reinforcement should be supported to ensure placement near the vertical midpoint of the concrete. "Hooking" of reinforcement is not considered an acceptable method of positioning the reinforcement. 5. Residential garage slabs should be a minimum of 5 inches thick and should be reinforced as above and poured separately from the structural footings and quartered with expansion joints or saw cuts. A positive separation from the footings should be maintained with expansion joint material to permit relative movement. 6. Specific presaturation is not required for these soil conditions; however, GSI recommends that the moisture content of the subgrade soils should be equal to or greater than optimum moisture content to a depth of 12 inches in the slab areas prior to the placement of visqueen. WALL DESIGN PARAMETERS Waterproofing Exterior basement or below -grade walls should be waterproofed. Gravel backdrains for the basement or below -grade should outlet via a sump pump or gravity drain to an approved outlet. In lieu of backdrains, the basement walls should be designed to withstand the increased hydrostatic pressure. Such pressures can be provided upon request. Conventional Retaining Walls The design parameters provided below assume that either non expansive soils (typically Class 2 permeable filter material or Class 3 aggregate base) or native onsite materials (up to and including an E.I. of 65) are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls, below grade, should be water - proofed or damp - proofed, depending Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:eAwp9 \4300 \4306bJcr Page 7 GeoSoils, Inc. on the degree of moisture protection desired. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no increase in bearing for footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re- entrant or male corners, should be designed for an at -rest equivalent fluid pressure (EFP) of 65 pounds per cubic foot (pcf), plus any applicable surcharge loading. For areas of male or re- entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (21-1) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 10 feet high. Design parameters for walls less than 3 feet in height may be superceded by City and /or County standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. SURFACE SLOPE OF EQUIVALENT EQUIVALENT RETAINED MATERIAL FLUID WEIGHT P.C.F. FLUID WEIGHT P.C.F. HORIZONTAL:VERTICAL SELECT BACKFILL NATIVE BACKFILL Level* 35 45 2 to 1 50 60 * Level backfill behind a retaining wall is defined as compacted earth materials, p roperly drained, without a slope for a distance of 2H behind the wall. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the back drainage options Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e: \wp9 \4300 \4306b.fcr Page 8 GeoSoils, Inc. DETAILS N T . S . 2 Native Backfill 1 Provide Surface Drainage Slope or Level Native Backfill 12" �— " Roc +12 k Filter Fabric Waterproofing 1 Membrane (optional) 1 or Flatter Weep Hole Native Backfill Finished Surface ® Pipe WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. ® ROCK: 3/4 to 1 -1/2" (inches) rock. (3 ) FILTER FABRIC: Mirafi 140N or approved equivalent; place fabric flap behind core. ® PIPE: 4" (inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. D WEEP HOLE: Minimum 2" (inches) diameter placed at 20' (feet) on centers along the wall, and 3" (inches) above finished surface. (No weep holes for basement walls.) TYPICAL RETAINING WALL BACKFILL AND DRAINAGE DETAIL DETAIL 1 Geotechnical • Geologic • Environmental DETAILS N T S . 2 Native Backfill 1 Provide Surface Drainage Slope or Level 6 " Native Backfill T_ Waterproofing Membrane (optional) Drain 1 Weep Hole 1 or Flatter Filter Fabric Finished Surface ® Pipe O WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. ® DRAIN: Miradrain 6000 or ] -drain 200 or equivalent for non - waterproofed walls. Miradrain 6200 or ] -drain 200 or equivalent for waterproofed walls. (3 ) FILTER FABRIC: Mirafi 140N or approved equivalent; place fabric flap behind care. ® PIPE: 4" (inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. D WEEP HOLE: Minimum 2" (inches) diameter placed at 20' (feet) on centers along the wall, and 3" (inches) above finished surface. (No weep holes for basement walls.) RETAINING WALL BACKFILL AND SUBDRAIN DETAIL " GEOTEXTILE DRAIN DETAIL 2 Geotechnical • Geologic • Environmental DETAILS N T S . 2 Native Backfill 1 Provide Surface Drainage Slope or Level H/2 min. +12" Waterproofing 1 Membrane (optional) 1 or Flatter H © Weep Hole Clean Sand Backfill Filter Fabric . Finished Surface ®Roe Pipe Heel Width 0 © WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. ® CLEAN SAND BACKFILL: Must have sand equivalent value of 30 or greater; can be densified by water jetting. (3 ) FILTER FABRIC: Mirafi 140N or approved equivalent. ® ROCK: 1 cubic foot per linear feet of pipe or 3/4 to 1 -1/2" (inches) rock. ® PIPE: 4" (inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. © WEEP HOLE: Minimum 2" (inches) diameter placed at 20' (feet) on centers along the wall, and 3" (inches) above finished surface. (No weep holes for basement walls.) RETAINING WALL AND SUBDRAIN DETAIL CLEAN SAND BACKFILL DETAIL 3 Geotechnical • Geologic • Environmental discussed below. Backdrains should consist of a 4 -inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or 3 /4 -inch to 1'h -inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wall may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an E.I. potential of greater than 65 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Outlets should consist of a 4 -inch diameter solid PVC or ABS pipe spaced no greater than ±100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes, only, in walls higher than 2 feet, is not recommended. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E. I. < 90). Proper surface drainage should also be provided. A water -proof membrane should be applied to the back of all below -grade retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Wall /Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2 -foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1/360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be placed no greater than 20 feet on- center, in accordance with the structural engineer's /wall designer's recommendations, regardless of whether or nottransition conditions exist. Expansion joints should be sealed with aflexible, non - shrink grout. c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e: \wp9 \4300 \4306bJcr Page 12 GeoSoils, Inc. TOP -OF -SLOPE WALLS /FENCES /IMPROVEMENTS Slope Creep Soils at the site may be expansive and therefore, may become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal changes in moisture content. Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and depth of these shrinkage cracks depend on many factors such as the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials experience a very slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 10 feet, this creep related soil movement will typically impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top of slope fences /walls. This influence is normally in the form of detrimental settlement, and tilting of the proposed improvements. The dessication /swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, the developer should provide this information to any homeowners and homeowners association. Top of Slope Walls /Fences Due to the potential for slope creep for slopes higher than about 10 feet, some settlement and tilting of the walls /fence with the corresponding distresses, should be expected. To mitigate the tilting of top of slope walls /fences, we recommend that the walls /fences be constructed on deepened foundations without any consideration for creep forces, where the expansion index of the materials comprising the outer 15 feet of the slope is less than 50, or a combination of grade beam and caisson foundations, for expansion indices greater than 50 comprising the slope, with creep forces taken into account. The grade beam should be at a minimum of 12 inches by 12 inches in cross section, supported by drilled caissons, 12 inches minimum in diameter, placed at a maximum spacing of 6 feet on center, and with a minimum embedment length of 7 feet below the bottom of the grade beam. The strength of the concrete and grout should be evaluated by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate sulfate corrosion, as warranted. The design of the grade beam and caissons should be in accordance with the recommendations of the project structural engineer, and include the utilization of the following geotechnical parameters: Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 File:e:\wp9 \4300 \4306bJcr Page 13 GeoSoils, Inc. Creep Zone: 5 -foot vertical zone belowthe slope face and projected upward parallel to the slope face. Creep Load: The creep load projected on the area of the grade beam should be taken as an equivalent fluid approach, having a density of 60 pcf. For the caisson, it should be taken as a uniform 900 pounds per linear foot of caisson's depth, located above the creep zone. Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive Resistance Passive earth pressure of 300 psf per foot of depth per foot of caisson diameter, to a maximum value of 4,500 psf may be used to determine caisson depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution of the creep prone zone above the point of fixity, to passive resistance, should be disregarded. Allowable Axial Capacity Shaft capacity: 350 psf applied below the point of fixity over the surface area of the shaft. Tip capacity: 4,500 psf. DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS The soil materials on site may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that the developer should notify any homeowners or homeowners association of this long- term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content, to a depth of 18 inches below subgrade elevation. If very low expansive soils are present, only optimum moisture content, or greater, is required and specific presoaking is not Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:eAwp9 \4300 \4306b.fcr Page 14 GeoSoiils, Inc. warranted. The moisture content of the subgrade should be proof tested within 72 hours prior to pouring concrete. 2. Concrete slabs should be cast over a non - yielding surface, consisting of a 4 -inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. If very low expansive soils are present, the rock or gravel or sand may be deleted. The layer or subgrade should be wet -down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and /or expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid - height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. If subgrade soils within the top 7 feet from finish grade are very low expansive soils (i.e., E.I. <_20), then 6x6- W1.4xW1.4 welded -wire mesh may be substituted for the rebar, provided the reinforcement is placed on chairs, at slab mid - height. The exterior slabs should be scored or saw cut, 1 /2 to 3 /8 inches deep, often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi. 6. Driveways, sidewalks, and patio slabs adjacent to the house should be separated from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the house. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e : \wp9 \4300 \4306b.fcr Page 15 GeoSoiils, Inc. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. If very low expansion soils are present, footings need only be tied in one direction. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 10. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept in mind that drainage reversals could occur, including post- construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the homeowner or homeowners association. 12. Air conditioning (A/C) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. A/C waste water lines should be drained to a suitable non - erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out -of -slope direction, after grading. This post- construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and is anticipated to potentially affect improvements or structures (e.g., separations and /or cracking), placed near the top -of- slope, up to a maximum distance of approximately 15 feet from the top -of- slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located Mr. Tim Clancy W_O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e:\wp9 \4300 \4306bJcr Page 16 GeoSonls, Inc. within the creep zone. LIFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long -term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the fill's optimum moisture content. It is generally not practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (per the 1997 UBC and /or adopted California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. Expansion joints in walls should be placed no greater than 20 feet on- center, and in accordance with the structural engineer's recommendations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and /or any homeowners association. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over - watering should be avoided as it adversely affects site improvements, and causes perched groundwater conditions. Graded slopes constructed utilizing onsite materials would be erosive. Eroded debris may be minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute -type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to develop. A rodent control program to prevent burrowing should be implemented. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over - steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and slopes. Surface drainage should be sufficient to prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken that Mr. Tim Clancy W_O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 File:e:\wp9 \4300 \4306b.fcr Page 17 GeoSoils, Inc. future landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and /or seep into the ground. In general, the area within 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of 1 percent sloping away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Erosion Control Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over - watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open -bottom planters adjacent to proposed structures be eliminated for a minimum distance of 10 feet. As an alternative, closed -bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetation. Consideration should be given to the type of vegetation chosen and their potential effect upon surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e:\wp9 \4300 \4306bJcr Page 18 GeoSoils, Inc. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes or other non - erosive devices (e.g., paved swales or ditches; below grade, solid tight -lined PVC pipes; etc.), that will carry the water away from the house, to an appropriate outlet, in accordance with the recommendations of the design civil engineer. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Site Improvements If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. Pools and /or spas should not be constructed without specific design and construction recommendations from GSI, and this construction recommendation should be provided to the homeowners, any homeowners association, and /or other interested parties. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench and retaining wall backfilis, flatwork, etc. Tile Floorinq Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs -on -grade where the will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e:\wp9 \4300 \4306b.fcr GeoSoiils, Inc. Page 19 Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street, driveway approaches, driveways, parking areas, and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to evaluate that the excavations have been made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgrade materials would be recommended at that time. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Trenching/Temporary Construction Backcuts Considering the nature of the onsite earth materials, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls /backcuts at the angle of repose (typically 25 to 45 degrees [except as specifically superceded within the text of this report]), should be anticipated. All excavations should be observed by an engineering geologist or soil engineer from GSI, prior to workers entering the excavation or trench, and minimally conform to CAL -OSHA, state, and local safety codes. Should adverse conditions exist, appropriate recommendations would be offered at that time. The above recommendations should be provided to any contractors and /or subcontractors, or homeowners, etc., that may perform such work. Utilily Trench Backfill 1. All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12 -inch to 18 -inch) under -slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to evaluate the desired results. 2. Exterior trenches adjacent to, and within areas extending below a 1:1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e: \wp9 \4300 \4306bJcr Page 20 GeoSoils, Inc. the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to evaluate the desired results. 3. All trench excavations should conform to CAL -OSHA, state, and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the structural engineer. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and /or testing be performed by GSI at each of the following construction stages: • During grading /recertification. • During excavation. • During placement of subdrains, toe drains, or other subdrainage devices, prior to placing fill and /or backfill. • After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. • Prior to pouring any slabs or flatwork, after presoaki n g/presatu ration of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea - gravel, etc.), or vapor barriers (i.e., visqueen, etc.). • During retaining wall subdrain installation, prior to backfill placement. • During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. • During slope construction /repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 File:eAwp9 \4300 \4306bJcr Page 21 GeoSoils, Inc. • When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed, prior to construction. • A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and /or to comply with code requirements. • GSI should review project sales documents to homeowners /homeowners associations for geotechnical aspects, including irrigation practices, the conditions outlined above, etc., prior to any sales. At that stage, GSI will provide homeowners maintenance guidelines which should be incorporated into such documents. OTHER DESIGN PROFESSIONALS /CONSULTANTS The design civil engineer, structural engineer, post- tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. This report presents minimum design criteria for the design of slabs, foundations and other elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer /designer. Please note that the recommendations contained herein are not intended to preclude the transmission of water or vapor through the slab or foundation. The structural engineer /foundation and /or slab designer should provide recommendations to not allow water or vapor to enter into the structure so as to cause damage to another building component, or so as to limit the installation of the type of flooring materials typically used for the particular application. The structural engineer /designer should analyze actual soil- structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness and deflections in the various slab, foundation, and other elements in order to develop appropriate, design - specific details. As conditions dictate, it is possible that other influences will also have to be considered. The structural engineer /designer should consider all applicable codes and authoritative sources where needed. If analyses by the structural engineer /designer result in less critical details than are provided herein as minimums, the minimums presented herein should be adopted. It is considered likely that some, more restrictive details will be required. If the structural engineer /designer has any questions or requires further assistance, they should not hesitate to call or otherwise transmit their requests to GSI. In order to mitigate potential distress, the foundation and /or improvement's designer should confirm to GSI and the governing agency, in writing, that the proposed foundations and /or improvements can tolerate the amount of differential settlement and /or expansion characteristics and other design criteria specified herein. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 File:e:\wp9 \4300 \4306b.fcr Page 22 GeoSoils, Inc. PLAN REVIEW Final project plans (grading, precise grading, foundation, retaining wall, landscaping, etc.), should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and /or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty, either express or implied, is given. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. All samples will be disposed of after 30 days, unless specifically requested by the client, in writing. Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 Fi1e:e:\wp9 \4300 \4306bJcr Page 23 GeoSoils, Inc. We appreciate this opportunity to be of service. If you have any questions, please call us at (760) 438 -3155. Respectfully submitted, GeoSoils, Inc. an E. Voss W- Sir, Staff Geologist 4T.51 NO. 4340 Ca�t�ed � Cl 11.�� J hn P. Franklin -rxr;,. / W. Skelly gineering Geologist, Gryl Civil Engineer, RCE 47 ® F BEV /JPF /DWS /jh Attachments: Table 1 - Field Density Test Results Plate 1 - Field Density Test Location Map Distribution: (2) Addressee (1) DZN Partners Architecture, Attention: Mr. Bart M. Smith (2) Gebco, Attention: Mike Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 14, 2005 File:e:\wp9 \4300 \4306bJcr Page 24 GeoSoils, Inc. Table 1 FIELD DENSITY TEST RESULTS TEST DATE TEST LOCATION ELEV MOISTURE DRY REL. TEST SOIL NO. OR: DENSITY COMP METHOD TYPE DEPTH {ft ) ... {PSI `) 1 1/27/05 South Corner Pool Area 72.0 13.9 112.9 93.9 ND A 2 1/27/05 North Corner Pool Area 74.0 13.5 113.1 94.0 ND A 3 1/28/05 South Corner Pool Area 74.0 13.5 112.0 93.1 ND A 4 1/28/05 North Corner Pool Area 72.0 13.6 111.9 93.0 ND A 5 1/28/05 Middle Lot Pool Area 72.0 13.0 117.0 90.3 ND B 6 1/31/05 South Corner Pool Area FG 13.1 112.4 93.5 ND A 7 2/2/05 North East Lot 72.0 11.0 119.8 91.8 SC B 8 2/2/05 North West Lot 72.0 12.0 120.4 92.9 ND B 9 2/3/05 South Rear Lot 72.0 13.0 121.0 93.4 ND B 10 2/3/05 North Front Lot 72.0 12.8 121.9 94.1 ND B 11 2/4/05 South Front Lot 64.0 13.0 122.0 94.2 ND B 12 2/4/05 South Front Lot 67.0 12.0 121.9 93.7 ND B 13 2/4/05 South Front Lot 70.0 11.9 119.9 92.5 SC B 14 2/4/05 South Front Lot 72.0 11.8 119.7 92.4 ND B 15 2/4/05 North West Corner FG 11.9 118.5 91.5 1 ND B 16 2/4/05 North East Corner FG 12.2 119.0 91.8 ND B 17 2/4/05 South West Corner FG 12.5 119.2 92.0 SC B 18 2/4/05 South East Corner FG 12.0 118.9 91.8 ND B LEGEND: FG = Finish Grade ND = Nuclear Densometer SC = Sand Cone Mr. Tim Clancy W.O. 4306 -B -SC 2145 Manchester Avenue, Encinitas February 2005 File: C:\excel \tables \4300 \4306b.fcr GeoSoils, Inc. Pagel S 9 Geotechnical • Geologic • Environmental 5741 Palmer Way Carlsbad, California 92008 • (760) 438 -3155 • FAX (760) 931 -0915 April 30, 2004 W.O.4306 -A -SC Mr. Tim Clancy P.O. Box 358 Cardiff, California 92007 Subject: Preliminary Geotechnical Evaluation, 2145 Manchester Avenue, City of Encinitas, San Diego County, California Dear Mr. Clancy: In accordance with your request, GeoSoils, Inc. (GSI) has performed a preliminary geotechnical evaluation of the subject site. The purpose of the study was to evaluate the onsite soils and geologic conditions and their effects on the proposed site development from a geotechnical viewpoint. EXECUTIVE SUMMARY Based on our review of the available data (see Appendix A), field exploration, laboratory testing, and geologic and engineering analysis, residential development of the property appears to be feasible from a geotechnical viewpoint, provided the recommendations presented in the text of this report are properly incorporated into the design and construction of the project. The most significant elements of this study are summarized below: • The proposed development will consist of two residential structures with basement /garage sub - floors and two additional stories above the sub - floors, as well as underground utility improvements. • Excavation into Quaternary-age terrace deposits will be necessary prior to foundation construction of the basement sub - floor. In general, unsuitable soils are on the order of ±1 to ±2 feet across a majority of the site. However, localized deeper removals cannot be precluded, should settlement- sensitive improvements be proposed within their influence. It is anticipated that the removal of unsuitable bearing materials will generally be performed by default during excavation for the garage /basement to design grades, and thus, should not adversely affect proposed superjacent improvements. • If settlement- sensitive improvements or substructures are proposed in the pool area, the pool shell should be completely removed, and replaced with properly compacted fill. Otherwise, prior to fill placement within the pool, the pool shell should be removed to a depth of 3 feet below grade. Core holes should be drilled through the pool shell to allow drainage. If the pool shell is left in- place, this condition should be disclosed to all homeowners and interested parties. • The expansion potential of tested onsite soils is very low. Conventional foundations may likely be utilized for these soil conditions. • Foundation systems should be designed to accommodate a worst -case differential settlement of at least 1 inch in a 40 -foot span. • At the time of this report, corrosion testing results had not been received for the subject site. An addendum report presenting those results will be provided when lab testing is complete. • Our evaluation indicates that proposed temporary construction slopes onsite may generally be considered surficially unstable, and may require shoring. Recommendations for shoring are provided herein. • In general, and based upon the available data to date, groundwater is not expected to be a major factor in development of the site; however, perched water may occur during construction and /or after site development, and should be anticipated. • Exterior basement walls should be waterproofed. If gravel backdrains for the basement walls are proposed, the drains should outlet via a sump pump. In lieu of backdrains, the basement walls may be designed to withstand the increased hydrostatic pressure. • Subsurface water is not anticipated to adversely affect site development, provided that the recommendations contained in this report are incorporated into final design and construction. These observations reflect site conditions at the time of our investigation and do not preclude future changes in local groundwater conditions from excessive irrigation, precipitation, or that were not obvious, at the time of our investigation. Seepage may occur locally (as the result of heavy precipitation or irrigation) in areas where any fill soils overlie terrace deposits or impermeable soils. Such conditions may occur during grading or afterthe site is developed, and should be anticipated. • Based on the available data, our evaluation indicates that the site has a very low potential for liquefaction. Therefore, no recommendations for mitigation are deemed necessary. • Our evaluation indicates there are no known active faults crossing the site. Mr. Tim Clancy W.O. 4306 -A -SC Fi1e:e: \wp9 \4300 \4306a.pge Page Two GeoSoils, Inc. • The seismic acceleration values and design parameters provided herein should be considered during the design of the proposed development. • Adverse geologic features that would preclude project feasibility were not encountered. • The recommendations presented in this report should be incorporated into the design and construction considerations of the project. The opportunity to be of service is greatly appreciated. If you have any questions concerning this report or if we may be of further assistance, please do not hesitate to contact the undersigned. GF� Respectfully submitted/ :.: GeoSoils, Inc. ' ( cOot_EY � No. 7571 Donna Gooley CA Project Geologist, R1 �F© y RGIE 4�` 1 sUi:i7 a ' ;; j N 1 C Wd w srrt�d P. a�}trYaO . n CF �' r �, ohn P. Franklin lA� �o`agist OQ David W. Skelly �'--- Engineering Geologist, Civil Engineer, RCE 4 57 DG /JPF /DWS /jk Distribution: (3) Addressee Mr. Tim Clancy W.O. 4306 -A -SC Fi1e:e:\wp9 \4300 \4306a.pge Page Three GeoSoils, Inc. TABLE OF CONTENTS SCOPE OF SERVICES .................... ............................... 1 SITE CONDITIONS /PROPOSED DEVELOPMENT .............................. 1 SITE EXPLORATION ....................... ..............................1 REGIONAL GEOLOGY .................... ............................... 3 SITE GEOLOGIC UNITS ................... ............................... 3 Topsoil /Colluvium ................... ............................... 3 Quaternary-age Terrace Deposits ...... ............................... 3 FAULTING AND REGIONAL SEISMICITY ...... ............................... 4 Faulting............................ ..............................4 Seismicity.......................... ..............................4 Seismic Shaking Parameters .......... ............................... 6 Seismic Hazards ..................... ..............................7 GROUNDWATER .......................... ..............................7 LABORATORY TESTING ................... ............................... 8 General............................ ..............................8 Classification ....................... ............................... 8 Laboratory Standard .................. ..............................8 Expansion Potential .................. ..............................8 Direct Shear Test .................... ..............................9 Corrosion /Sulfate Testing ............. ............................... 9 CONCLUSIONS ........................... ..............................9 EARTHWORK CONSTRUCTION RECOMMENDATIONS ........................ 9 General............................ ..............................9 Site Preparation ..................... .............................10 Removals (Unsuitable Surficial Materials) .............................. 10 Fill Placement ....................... .............................10 Backfillof Pool ...................... .............................10 Transitions /Overexcavation .......... ............................... 11 Temporary Construction Slopes ...... ............................... 11 Preliminary Shoring Recommendations ............................... 11 General............................ .............................11 Lateral Pressures .................... .............................11 Design of Soldier Piles .............. ............................... 12 Lagging ............................ .............................12 Internal Bracing ..................... .............................12 Deflection .......................... .............................12 Monitoring .......................... .............................12 GeoSoils, Inc. RECOMMENDATIONS - FOUNDATIONS ..... ............................... 13 Preliminary Foundation Design ....... ............................... 13 Bearing Value ....................... .............................13 Lateral Pressure ..................... .............................13 Foundation Settlement ................ .............................14 Footing Setbacks .................... .............................14 Construction ........................ .............................14 Very Low Expansion Potential (E.I. 0 to 20) ............................ 14 UTILITIES ................................ .............................15 WALL DESIGN PARAMETERS ............. ............................... 16 Conventional Retaining Walls ........ ............................... 16 Restrained Walls ..................... .............................16 Cantilevered Walls ................. ............................... 16 Retaining Wall Backfill and Drainage ... ............................... 17 Wall /Retaining Wall Footing Transitions ............................... 17 TOP -OF -SLOPE WALLS /FENCES /IMPROVEMENTS .......................... 21 SlopeCreep ........................ .............................21 Top of Slope Walls /Fences .......... ............................... 21 DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS ....................... 23 .................................. .............................25 DEVELOPMENT CRITERIA ................ ............................... 25 Slope Deformation ................. ............................... 25 Slope Maintenance and Planting ...... ............................... 25 Drainage ............................ .............................26 Toe of Slope Drains/Toe Drains ....... ............................... 26 Erosion Control ...................... .............................27 Landscape Maintenance .............. .............................27 Gutters and Downspouts ............ ............................... 30 Subsurface and Surface Water ......... .............................30 Site Improvements ................. ............................... 30 Tile Flooring ........................ .............................30 Additional Grading ................... .............................31 Footing Trench Excavation ............ .............................31 Trenching .......................... .............................31 Utility Trench Backfill ............... ............................... 31 SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING ........................... .............................32 Mr. Tim Clancy Table of Contents F11e:e: \wp9 \4300 \4306a.pge Page ii GeoSoils, Inc. OTHER DESIGN PROFESSIONALS /CONSULTANTS .......................... 33 PLAN REVIEW ............................ ............................. LIMITATIONS............................. ............................. FIGURES: Figure 1 - Site Location Map .......... ............................... 2 Figure 2 - California Fault Map ......... ............................... 5 Detail 1 - Typical Retaining Wall backfill and Drainage Detail .............. 18 Detail 2 - Retaining Wall Backfill and Subdrain detail Geotextile Drain ....... 19 Detail 3- Retaining Wall and Subdrain Detail Clean Sand Backfill ........... 20 Detail 4 - Schematic Toe Drain Detail .. ............................... 28 Detail 5 - Subdrain Along Retaining Wall Detail ......................... 29 ATTACHMENTS: Appendix A - References .... ............................... Rear of Text Appendix B - Test Pit Logs ... ............................... Rear of Text Appendix C - EQFAULT, EQSEARCH, AND FRISKSP ............ Rear of Text Appendix D - General Earthwork and Grading Guidelines ......... Rear of Text Plate 1 - Boring Location Map ....................... Rear of Text in Folder Mr. Tim Clancy Table of Contents Fi1e:eAwp9 \4300 \4306a.pge Page iii GeoSoils, Inc. PRELIMINARY GEOTECHNICAL EVALUATION 2145 MANCHESTER AVENUE CITY OF ENCINITAS, SAN DIEGO COUNTY, CALIFORNIA SCOPE OF SERVICES The scope of our services has included the following: 1. Review of the available geologic literature for the site (see Appendix A). 2. Geologic site reconnaissance, subsurface exploration, sampling, and mapping. 3. Appropriate laboratory testing of representative soil samples. 4. General areal seismicity evaluation. 5. Engineering and geologic analysis of data collected. 6. Preparation of this report and accompaniments. SITE CONDITIONS /PROPOSED DEVELOPMENT The site consists of a rectangular, gently westward sloping property, located on the east side of Manchester Avenue, at 2145 Manchester Avenue, in the City of Encinitas, San Diego County, California (see Figure 1, Site Location Map). The property is currently occupied by a residence and a pool. The project area is located approximately 80 feet above Mean Sea Level (MSL). Site development is anticipated to consist of demolition of existing structures, and preparing the property for the construction of two residential structures, with basement /garage sub -floors and two additional stories above the sub - floors, as well as underground utility improvements and sloping driveways into the two sunken garages. It is proposed that the garage portion of the sub -floor will be 4 feet below existing grade, and the remaining storage area will rise to existing grade. We understand that the proposed structures will utilize continuous footings with slabs -on -grade and wood -frame construction. Building loads are assumed to be typical for this type of relatively light construction. It is anticipated that sewage disposal will be tied into the regional municipal system. The need for import soils is unknown; however, we understand that it is proposed to backfill the existing pool. SITE EXPLORATION Surface observations and subsurface exploration were performed on April 15, 2004, by a representative of this office. A survey of line and grade for the subject site was not conducted by this firm at the time of our site reconnaissance. Near surface soil conditions were explored with four exploratory hand auger borings within the site to evaluate soil and geologic conditions. The approximate location of each boring is shown on the Boring Location Map (Plate 1). Boring Logs are presented in Appendix B. GeoSoils, Inc. 3-D TopoQuads Copyright 0 1999 DeLome Yarmouth, NJE o4o% ZZI* 19 -A % DR. SITE Cardiff-by-the-Sea (Cardiff) e 10 J D Vi 0 2 9) 5 21 Base Map: Encinitas Quadrangle, California--San Diego Co., 7.5 Minute Series (Topographic), 1968 (photo revised 1975), by USGS, 1"=2000' CT BRIOGF p�"V*EEX CA A WY ZOO TENNIS CLUB S 'ICK ARD, S_ --,. A l A R I IFF LOW CARD flj I PA 28 Lh SPORTS 23 W C:) SAN ELIJO STATE BEACH R CM tw CT HURST, CNA, ON N -104 15 AV! �� OR V) WISAS 300 SEi EM S I V TE V A� HI, A COSTA 1 I DR Ci XL02V T, -C ri X I \ IiOl 41, Cr NCHEST io 4 26 - 41 - pGEAN SAN EL IX Base Map: The Thomas Guide, San Diego County Street Guide and Directory, 2004 Edition, by Thomas Bros. Maps, page 1167, 1"=1/2 mile Reproduced with permission gr anted by Thomas Bros. Maps. I map is copyrighted by MSS Bros. MAPS. it is unlawful to COPy or reproduce an or any part thereof, whether for personal use Of resale, without Permission. All rights reserved. W.O. 4306-A-SC SITE LOCATION MAP Figure 1 REGIONAL GEOLOGY The subject property is located within a prominent natural geomorphic province in southwestern California known as the Peninsular Ranges. It is characterized by steep, elongated mountain ranges and valleys that trend northwesterly. The mountain ranges are underlain by basement rocks consisting of pre- Cretaceous metasedimentary rocks, Jurassic metavolcanic rocks, and Cretaceous plutonic rocks of the southern California batholith. In the San Diego County region, deposition occurred during the Cretaceous Period of the Cenozoic Era in the continental margin of a forearc basin. Sediments, derived from Cretaceous -age plutonic rocks and Jurassic -age volcanic rocks, were deposited into the narrow, steep, coastal plain and continental margin of the basin. These rocks have been uplifted, eroded, and deeply incised. During early Pleistocene time, a broad coastal plain was developed from the deposition of marine terrace deposits. During mid- to late- Pleistocene time, this plain was uplifted, eroded, and incised. Alluvial deposits have since filled the lower valleys, and young marine sediments are currently being deposited /eroded within coastal and beach areas. SITE GEOLOGIC UNITS The site geologic units encountered during our subsurface investigation and site reconnaissance included topsoil /colluvium and terrace deposits. The earth materials are generally described below, from the youngest to the oldest. Topsoil /colluvium Topsoil (colluvium), consisting of brown, moist, loose, silty sands, approximately 1 to ±1'/2 feet thick, was observed mantling the site. These soils are considered potentially compressible in their existing state, and will require removal during any future grading within the site, if settlement- sensitive improvements are proposed in those areas. The earth materials can be reused as compacted fill, provided deleterious material has been removed. Quaternary -age Terrace Deposits Terrace deposits were observed to underlie the site and consist generally of massive, loose to dense with depth, silty sands. These deposits are generally orange brown in color, and moist. The upper 1 foot of these materials are generally weathered and considered unsuitable for structural support in their present condition, and should be removed and recompacted, should settlement- sensitive improvements be proposed within their influence. These deposits may be locally friable. Temporary construction slopes onsite may be surficially unstable and may require shoring. Recommendations for shoring are provided herein. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 3 GeoSoiils, Inc. FAULTING AND REGIONAL SEISMICITY Faulting The site is situated in a region of active, as well as potentially- active, faults. Our review indicates that there are no known active faults crossing the site within the areas proposed for development (Jennings, 1994), and the site is not within an Earthquake Fault Zone (Hart and Bryant, 1997). There are a number of faults in the southern California area that are considered active and would have an effect on the site in the form of ground shaking, should they be the source of an earthquake (see Figure 2, California Fault Map). These faults include, but are not limited to: the San Andreas fault; the San Jacinto fault; the Elsinore fault; the Coronado Bank fault zone; and, the Newport- Inglewood - Rose Canyon fault zone. The possibility of ground acceleration, or shaking at the site, may be considered as approximately similar to the southern California region as a whole. The following table lists the major faults and fault zones in southern California that could have a significant effect on the site should they experience significant activity. ABBREVIATED FAULT NAME. APPROXIMATE DISTANCE MILES'' KM Coronado Bank -Agua Blanca 17.2 (27.7) Elsinore- Julian 29.0 (46.6) Newport- Inglewood- Offshore 12.9 (20.7) Rose Canyon 3.0 (4.9) Elsinore- Temecula 29.1 46.8 Seismicity The acceleration- attenuation relations of Sadigh, et al. (1997) Horizontal Soil, Bozorgnia, Campbell, and Niazi (1999) Horizontal -Soft Rock - Correlation, and Campbell and Bozorgnia (1997 Rev.) Horizontal -Soil have been incorporated into EQFAULT (Blake, 2000a). Forthis study, peak horizontal ground accelerations anticipated atthe site were determined based on the random mean plus 1 - sigma attenuation curve and mean attenuation curve developed by Joyner and Boore (1981, 1982a, 1982b, 1988, 1990), Bozorgnia, Campbell, and Niazi (1999), and Campbell and Bozorgnia (1997). EQFAULT is a computer program by Thomas F. Blake (2000a), which performs deterministic seismic hazard analyses using up to 150 digitized California faults as earthquake sources. Mr. Tim Clancy W.O.4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 4 GeoSoils, Inc. CALIFORNIA FAULT MAP 2145 Manchester 1100 1000 900 800 700 600 500 400 300 200 100 o " SI 0 -100 1111111 lilt 11111111111 -400 -300 -200 -100 0 100 200 300 400 500 600 W.O. 4306 -A -SC Figure 2 GeoSoils, Inc. The program estimates the closest distance between each fault and a given site. If a fault is found to be within a user - selected radius, the program estimates peak horizontal ground acceleration that may occur at the site from an upper bound ( "maximum credible ") earthquake on that fault. Site acceleration (g) is computed by one of many user - selected acceleration- attenuation relations that are contained in EQFAULT. Based on the EQFAULT program, peak horizontal ground accelerations from an upper bound event at the site may be on the order of 0.81 g to 0.87g. Historical site seismicity was evaluated with the acceleration- attenuation relations of Bozorgnia, Campbell and Niazi (1999) Horizontal -Soft Rock - Correlation and the computer program EQSEARCH (Blake, 2000b). This program performs a search of the historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100 -mile radius, between the years 1800 through December 2003. Based on the selected acceleration - attenuation relationship, a peak horizontal ground acceleration is estimated, which may have effected the site during the specific event listed. Based on the available data and the attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 through 2003 was 0.85g. Site specific probability of exceeding various peak horizontal ground accelerations and a seismic recurrence curve are also estimated /generated from the historical data. Computer printouts of pertinent portions of the EQSEARCH program are presented in Appendix C. A probabilistic seismic hazards analyses was performed using FRISKSP (Blake, 2000c) which models earthquake sources as 3 -D planes and evaluates the site specific probabilities of exceedance for given peak acceleration levels or pseudo - relative velocity levels. Based on a review of these data, and considering the relative seismic activity of the southern California region, a peak horizontal ground acceleration of 0.45g was calculated. This value was chosen as it corresponds to a 10 percent probability of exceedance in 50 years (or a 475 -year return period). Seismic Shaking Parameters Based on the site conditions, Chapter 16 of the Uniform Building Code ([UBC], International Conference of Building Officials [ICBO], 1997), the following seismic parameters are provided. Seismic zone (per Figure 16 -2 *) 4 Seismic Zone Factor (per Table 16 -1 *) 0.40 Soil Profile Type (per Table 16 -J *) Sp Seismic Coefficient C (per Table 16 -Q *) 0.44 N. Seismic Coefficient C, (per Table 16 -R *) 0.64 N„ Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 6 GeoSoils, Inc. Near Source Factor N (per Table 16 -S *) 1.0 Near Source Factor N, (per Table 16 -T *) 1.2 Seismic Source Type (per Table 16 -U *) B Distance to Seismic Source 3.Omi. (4.9 km) Upper Bound Earthquake [Rose Canyon] M,, 6.9 * Figure and table references from Chapter 16 of the UBC ICBO, 1997). Seismic Hazards The following list includes other seismic related hazards that have been considered during our evaluation of the site. The hazards listed are considered negligible and /or completely mitigated as a result of site location, depth to regional groundwater, soil characteristics, and typical site development procedures: • Liquefaction • Tsunami • Seiche • Dynamic Settlement • Surface Fault Rupture • Ground Lurching or Shallow Ground Rupture It is important to keep in perspective that in the event of a maximum probable or credible (upper bound) earthquake occurring on any of the nearby major faults, strong ground shaking would occur in the subject site's general area. Potential damage to any structure(s) would likely be greatest from the vibrations and impelling force caused by the inertia of a structure's mass, than from those induced by the hazards considered above. This potential would be no greater than that for other existing structures and improvements in the immediate vicinity. GROUNDWATER Subsurface water was not encountered within the property during field work performed in preparation of this report. Subsurface water is not anticipated to adversely affect site development, provided thatthe recommendations contained in this report are incorporated into final design and construction. These observations reflect site conditions at the time of our investigation and do not preclude future changes in local groundwater conditions from excessive irrigation, precipitation, or that were not obvious, at the time of our investigation. Regional groundwater is estimated to be at least 60 feet in depth, below the site. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 7 GeoSoils, Inc. Seeps, springs, or other indications of a high groundwater level were not noted on the subject property during the time of our field investigation. However, seepage may occur locally (as the result of heavy precipitation or irrigation) in areas where any fill soils overlie terrace deposits or impermeable soils. Such conditions may occur during grading or after the site is developed, and should be anticipated. LABORATORY TESTING General Laboratory tests were performed on representative samples of the onsite earth materials in order to evaluate their physical characteristics. The test procedures used and results obtained are presented below. Classification Soils were classified visually according to the Unified Soils Classification System (USCS). The soil classifications are shown on the Boring Logs in Appendix B. Laboratory Standard The maximum dry density and optimum moisture content was determined forthe major soil type encountered in the borings. The laboratory standard used was ASTM D -1557. The moisture - density relationship obtained for this soil is shown below: SOIL TYPE BORING AND _ MAXIMUM DRY OPTIMUM MOISTURE , DEPTH FT: DENSITY" PC CONTENT % SILTY SAND, Oran a Brown B -1 @ 0 -4 120.2 13.0 Expansion Potential Expansion testing was performed on representative samples of site soil in accordance with UBC Standard 18 -2. The results of expansion testing are presented in the following table. ". LOCATION . EXPANSION INDEX �;,. EXPANSION POTENTIAL B -1 a 04 1 Very Low Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 8 GeoSoils, Inc. Direct Shear Test Shear testing was performed on a representative, disturbed sample of site soil in general accordance with ASTM Test Method D -3080 in a Direct Shear Machine of the strain control type. The shear test result is as follows: PRIMARY RESIDUAL SAMPLE LOCATION COHESION FRICTION ANGLE COHESION FRICTION ANGLE (PSF) (DEGREES) (PSF) (DEGREES) B -1 @ 0 -4' 94 35 112 33 Corrosion /Sulfate Testing Laboratory test results for soluble sulfates, pH, and corrosion to metals have not been received as of the date of this report. Testing will be presented as an addendum upon receipt of the results. Additional testing of site materials is recommended when proposed grading is complete, to further evaluate the findings. CONCLUSIONS Based upon our site reconnaissance, subsurface exploration, and laboratory test results, it is our opinion that the subject site appears suitable for the proposed residential development. The following recommendations should be incorporated into the construction details. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All grading should conform to the guidelines presented in Appendix Chapter A33 of the UBC, the requirements of the City, and the Grading Guidelines presented in Appendix D, except where specifically superceded in the text of this report. Prior to grading, a GSI representative should be present at the preconstruction meeting to provide additional grading guidelines, if needed, and review the earthwork schedule. During earthwork construction, all site preparation and the general grading procedures of the contractor should be observed and the fill selectively tested by a representatives) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and, if warranted, modified and /or additional recommendations will be Mr. Tim Clancy W.O.4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 9 GeoSoiiis, I>ne. offered. All applicable requirements of local and national construction and general industry safety orders, the Occupational Safety and Health Act, and the Construction Safety Act should be met. Site Preparation Debris, vegetation, existing structures, and other deleterious material should be removed from the building area prior to the start of construction. Sloping areas to receive fill should be properly benched in accordance with current industry standards of practice and guidelines specified in the UBC. Removals (Unsuitable Surficial Materials) Due to the relatively loose condition of topsoil and weathered terrace deposits, these materials should be removed and recompacted in areas proposed for settlement- sensitive structures or areas to receive compacted fill. At this time, removal depths on the order of 1 to 2 feet (including topsoil and weathered terrace deposits) below existing grade should be anticipated throughout a majority of the site; however, locally deeper removals cannot be precluded. Removals should be completed below a 1:1 projection down and away from the edge of any settlement- sensitive improvements and /or limits of proposed fill. Once removals are completed, the exposed bottom should be reprocessed and compacted to 90 percent relative compaction. Fill Placement Subsequent to ground preparation, onsite soils may be placed in thin ( ±6 -inch) lifts, cleaned of vegetation and debris, brought to a least optimum moisture content, and compacted to achieve a minimum relative compaction of 90 percent. if soil importation is planned, a sample of the soil import should be evaluated by this office prior to importing, in order to assure compatibility with the onsite site soils and the recommendations presented in this report. Import soils for a fill cap should be very low expansive (Expansion Index [E.I.] less than 21). The use of subdrains at the bottom of the fill cap may be necessary, and subsequently recommended based on compatibility with onsite soils and proximity and /or suitability of an outlet. Backfill of Pool If settlement- sensitive improvements or substructures are proposed in the pool area, the pool shell should be completely removed, and replaced with properly compacted fill. Otherwise, prior to fill placement within the pool, the pool shell should be removed to a depth of 3 feet below pad grade. Core holes should be drilled through the pool shell to allow drainage. If the pool shell is left in- place, this condition should be disclosed to all homeowners and interested parties. Mr. Tim Clancy W.O.4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 10 GeoSoiis, Inc. Transitions / Overexcavation Cut portions of cut /fill transition pads should be overexcavated a minimum 3 feet below pad grade. Areas with planned fills less than 3 feet should be overexcavated in order to provide a minimum fill thickness of 3 feet, on a preliminary basis. Where the ratio of maximum to minimum fill thickness below a given structure exceeds 3:1, overexcavation should be completed to reduce this ratio to 3:1, or less. Temporary Construction Slopes Proposed site development consists of excavation for garage /basement sub - floors. Temporary cuts for wall construction should be constructed at a gradient of 1:1, or flatter, for slopes exposing terrace deposit materials to a maximum height of 15 feet, per CAL -OSHA for Type B soils. Construction materials and /or stockpiled soil should not be stored within 5 feet of the top of any temporary slope. Temporary/permanent provisions should be made to direct any potential runoff away from the top of temporary slopes. Shoring will likely be required, if friable conditions are encountered in the terrace deposits. Preliminary Shoring Recommendations General Should insufficient space for constructing portions of the proposed residence be encountered, shoring may be required. Shoring should consist of cantilever steel soldier beams placed at a maximum of 6 -foot on centers, with a minimum embedment below the bottom of the cut, equivalent to half the height of the cut. The ultimate embedment depth should be provided by the project structural engineer and /or shoring designer, based on the geotechnical parameters provided herein. Wood lagging should be installed as the cut progresses to its ultimate configuration. Lateral Pressures For design on cantilevered shoring, a triangular distribution of lateral earth pressure may be used. It may be assumed that the retained soils with a level surface behind the shoring will exert a lateral pressure equal to that developed by a fluid with a density of 40 pcf. Retained soils with a 2:1 back slope ratio will exert a lateral pressure equal to a fluid with a density of 60 pcf. If street traffic is located within 10 feet of shorings, the upper 10 feet of shoring adjacent to the traffic should be designed to resist a uniform lateral pressure of 100 pounds per square foot (psf), which is a result of an assumed 300 psf surcharge behind the shoring due to normal street traffic. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 11 GeoSoils, Inc. Design of Soldier Piles For the design of soldier piles spaced at least 2 diameters on centers, the allowable lateral bearing value (passive value) of the soils below the level of excavation may be assumed to be 500 psf per foot of depth, up to a maximum of 5,000 psf. To develop the full lateral value, provisions should be taken to assure firm contact between the soldier piles and the undisturbed soils. The soldier piles below the excavated levels may be used to resist downward loads, if any. The downward frictional resistance between the soldier piles and the soils below the excavated level may be taken as equal to 300 psf. Lagging Continuous wood lagging will be required between the soldier piles. The soldier piles should be designed for the full anticipated lateral pressure. However, the pressure on the lagging will be less due to arching in the soils. We recommend that the lagging be designed for the recommended earth pressure, but limited to a maximum value of 500 psf. Internal Bracing Rakers may be required to internally brace the soldier piles. The raker bracing could be supported laterally by temporary concrete footings (deadmen) or by the permanent interior footings. For design of temporary footings, or deadmen, poured with the bearing surface normal to rakers inclined at 45 degrees, a bearing value of 2,500 psf may be used, provided the shallowest point of the footing is at least 1 foot below the lowest adjacent grade. Deflection It is difficult to accurately predict the amount of deflection of a shored profile. It should be realized, however, that some deflection will occur. We anticipate that this deflection would be on the order of 1 /2 inch at the top of the planned 10- to 12 -foot shoring. If greater deflection occurs during construction, additional bracing may be necessary to minimize deflection. If desired to reduce the deflection of the shoring, a greater active pressure leading to a more stiffer section could be used. Monitoring Some means of monitoring the performance of the shoring system is recommended. The monitoring should consist of periodic surveying of the lateral and vertical locations of the tops of all the soldier piles and the lateral movement along the entire lengths of selected soldier piles. We suggest that photographs of the adjacent improvements be made prior to excavation. Mr. Tim Clancy W.O.4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 12 GeoSoiils, Inc. RECOMMENDATIONS - FOUNDATIONS Preliminary Foundation Design In the event that the information concerning the proposed development plans are not correct or any changes in the design, location, or loading conditions of the proposed structures are made, the conclusions and recommendations contained in this report are for the subject site only and shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. The information and recommendations presented in this section are considered minimums and are not meant to supercede design(s) by the project structural engineer or civil engineer specializing in structural design. Upon request, GSI could provide additional consultation regarding soil parameters, as related to foundation design. They are considered preliminary recommendations for proposed construction, in consideration of our field investigation, and laboratory testing and engineering analysis. Our review, field work, and recent and previous laboratory testing indicates that onsite soils have a very low expansion potential range (E.I. 0 to 20). Preliminary recommendations for foundation design and construction are presented below. Final foundation recommendations should be provided at the conclusion of grading based on laboratory testing of fill materials exposed at finish grade. Bearing Value 1. The foundation systems should be designed and constructed in accordance with guidelines presented in the latest edition of the UBC. 2. An allowable bearing value of 2,000 psf may be used for design of continuous footings 12 inches wide and 12 inches deep and for design of isolated pad footings 24 inches square and 24 inches deep founded entirely into compacted fill or competent formational material and connected by grade beam or tie beam in at least one direction. This value may be increased by 20 percent for each additional 12 inches in depth to a maximum value of 3,000 psf. The above values may be increased by one -third when considering short duration seismic or wind loads. No increase in bearing for footing width is recommended. Lateral Pressure 1. For lateral sliding resistance, a 0.35 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. 2. Passive earth pressure may be computed as an equivalent fluid having a density of 250 pounds per cubic foot (pcf), with a maximum earth pressure of 2,500 psf. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 13 GeoSoiils, Inc. 3. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one - third. Foundation Settlement Foundations systems should be designed to accommodate a worst case differential settlement of 1 inch in a 40 -foot span. Footing Setbacks All footings should maintain a minimum 7 -foot horizontal setback from the base of the footing to any descending slope. This distance is measured from the footing face at the bearing elevation. Footings should maintain a minimum horizontal setback of H/3 (H =slope height) from the base of the footing to the descending slope face, and no less than 7 feet nor need to be greater than 40 feet. Footings adjacent to unlined drainage swales should be deepened to a minimum of 6 inches below the invert of the adjacent unlined swale. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1:1 projection from the heel of the wall. Alternatively, walls may be designed to accommodate structural loads from buildings or appurtenances as described in the Retaining Wall section of this report. Construction The following foundation construction recommendations are presented as a minimum criteria from a soils engineering standpoint. The onsite soils expansion potentials are generally very low (E.I. 0 to 20). Recommendations for very low expansive soil conditions are presented herein. Recommendations by the project's design - structural engineer or architect, which may exceed the soils engineer's recommendations, should take precedence over the following minimum requirements. Final foundation design will be provided based on the expansion potential of the near surface soils encountered during grading. Very Low Expansion Potential (E.I. 0 to 20) 1. Exterior and interior footings should be founded at a minimum depth of 12 inches for one -story floor loads, 18 inches for two -story floor loads, and 24 inches for three -story floor loads below the lowest adjacent ground surface. Isolated column and panel pads, or wall footings, should be founded at a minimum depth of 24 inches. All footings should be reinforced with two No. 4 reinforcing bars, one placed near the top and one placed near the bottom of the footing. Footing widths should be as indicated in the UBC (ICBO, 1997); width of 12 inches for one -story loads, 15 inches for two -story loads, and 18 inches for three -story loads. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 14 GeoSoils, Inc. 2. A grade beam, reinforced as above, and at least 12 inches wide should be provided across large (e.g., doorways) entrances. The base of the grade beam should be at the same elevation as the bottom of adjoining footings. Isolated, exterior square footings should be tied within the main foundation in at least one direction with a grade beam. 3. Residential concrete slabs, where moisture condensation is undesirable, should be underlain with a vapor barrier consisting of a minimum of 10 mil polyvinyl chloride or equivalent membrane with all laps sealed. This membrane should be covered above and below with a minimum of 2 inches of sand (total of 4 inches) to aid in uniform curing of the concrete and to protect the membrane from puncture. 4. Residential concrete slabs should be a minimum of 4 inches thick, and should be reinforced with No. 3 reinforcing bar at 18 inches on center in both directions. All slab reinforcement should be supported to ensure placement near the vertical midpoint of the concrete. "Hooking" of reinforcement is not considered an acceptable method of positioning the reinforcement. 5. Residential garage slabs should be a minimum of 5 inches thick and should be reinforced as above and poured separately from the structural footings and quartered with expansion joints or saw cuts. A positive separation from the footings should be maintained with expansion joint material to permit relative movement. 6. Specific presaturation is not required for these soil conditions; however, GSI recommends that the moisture content of the subgrade soils should be equal to or greater than optimum moisture content to a depth of 12 inches in the slab areas prior to the placement of visqueen. UTILITIES Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. Due to the potential for differential settlement, air conditioning (A/C) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. A/C waste waterlines should be drained to a suitable outlet. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e :wp9 \4300 \4306a.pge Page 15 GeoSoiiis, Inc. WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that either non expansive soils (Class 2 permeable filter material or Class 3 aggregate base) or native materials (up to and including an E.I. of 65) are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls, below grade, should be water - proofed or damp - proofed, depending on the degree of moisture protection desired. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no increase in bearing for footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re- entrant or male corners, should be designed for an at -rest equivalent fluid pressure (EFP) of 65 pcf, plus any applicable surcharge loading. For areas of male or re- entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 10 feet high. Design parameters for walls less than 3 feet in height may be superceded by City and /or County standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 File:e:wp9 \4300 \4306a.pge Page 16 GeoSoils, Inc. SURFACE SLOPE OF EQUIVALENT EQUIVALENT RETAINED MATERIAL FLUID WEIGHT P.C.F. FLUID WEIGHT P.C.F. HORIZONTAL:VERTICAL SELECT BACKFILL NATIVE BACKFILL Level* 35 45 2 to 1 50 60 * Level backfill behind a retaining wall is defined as compacted earth materials, p roperly drained, without a slope for a distance of 2H behind the wall. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the back drainage options discussed below. Backdrains should consist of a 4 -inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or' /z -inch to 3 /4 -inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wall may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an E.I. potential of greater than 65 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Outlets should consist of a 4 -inch diameter solid PVC or ABS pipe spaced no greater than ±100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.I. <90). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water -proof membrane to the back of all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Wall /Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 17 GeoSoils, Inc. DETAILS N T . S . 2 Native Backfill 1 Provide Surface Drainage Slope or Level Native Backfill 12" +12" Rock Q Filter Fabric Waterproofing 1 Membrane (optional) 1 or Flatter © Weep Hole Native Backfill Finished Surface ® Pipe WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. ® ROCK: 3/4 to 1 -1/2" (inches) rock. . (3 ) FILTER FABRIC: Mirafi 140N or approved equivalent; place fabric flap behind core. ® PIPE: 4" (inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. ® WEEP HOLE: Minimum 2" (inches) diameter placed at 20' (feet) on centers along the wall, and 3" (inches) above finished surface. (No weep holes for basement walls.) TYPICAL RETAINING WALL BACKFILL AND DRAINAGE DETAIL �> DETAIL 1 Geotechnical • Geologic a Environmental DETAILS N T S . 2 Native Backfill 1 Provide Surface Drainage Slope or Level 6 Native Backfill (!)Waterproofing Membrane (optional) © Drain 1 Weep Hole 1 or Flatter Filter Fabric Finished Surface ® Pipe O © WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. ® DRAIN: Miradrain 6000 or J -drain 200 or equivalent for non - waterproofed walls. Miradrain 6200 or ]-drain 200 or equivalent for waterproofed walls. O FILTER FABRIC: Mirafi 140N or approved equivalent; place fabric flap behind care. ® PIPE: 4" (inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. ® WEEP HOLE: Minimum 2" (inches) diameter placed at 20' (feet) on centers along the wall, and 3" (inches) above finished surface. (No weep holes for basement walls.) RETAINING WALL BACKFILL AND SUBDRAIN DETAIL •' GEOTEXTILE DRAIN l • DETAIL 2 Geotechnical • Geologic • Environmental DETAILS N T S . 2 Native Backfill 1 Provide Surface Drainage Slope or Level H/2 min. +12" Waterproofing 1 Membrane (optional) 1 or Flatter H . © Weep Hole 0 Clean Sand Backfill 0 Filter Fabric . Finished Surface ® Roc © Pipe -► Heel Width �-- WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. ® CLEAN SAND BACKFILL: Must have sand dequivalent value of 30 or greater; can be densified by water jetting. OO FILTER FABRIC: Mirafi 140N or approved equivalent. ® ROCK: 1 cubic foot per linear feet of pipe or 3/4 to 1 -1/2" (inches) rock. ® PIPE: 4" (inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. © WEEP HOLE: Minimum 2" (inches) diameter placed at 20' (feet) on centers along the wall, and 3" (inches) above finished surface. (No weep holes for basement walls.) RETAINING WALL AND SUBDRAIN DETAIL CLEAN SAND BACKFILL • DETAIL 3 Geotechnical • Geologic • Environmental a) A minimum of a 2 -foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1/360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be sealed with a flexible, non - shrink grout. c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. TOP -OF -SLOPE WALLS /FENCES /IMPROVEMENTS Slope Creep Soils at the site may be expansive and therefore, may become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal changes in moisture content. Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and depth of these shrinkage cracks depend on many factors such as the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials experience a very slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 10 feet, this creep related soil movement will typically impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top of slope fences /walls. This influence is normally in the form of detrimental settlement, and tilting of the proposed improvements. The dessication /swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, the developer should provide this information to any homeowners and homeowners association. Top of Slope Walls /Fences Due to the potential for slope creep for slopes higher than about 10 feet, some settlement and tilting of the walls /fence with the corresponding distresses, should be expected. To mitigate the tilting of top of slope walls /fences, we recommend that the walls /fences be Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 21 GeoSoils, Inc. constructed on deepened foundations without any consideration for creep forces, where the expansion index of the materials comprising the outer 15 feet of the slope is less than 50, or a combination of grade beam and caisson foundations, for expansion indices greater than 50 comprising the slope, with creep forces taken into account. The grade beam should be at a minimum of 12 inches by 12 inches in cross section, supported by drilled caissons, 12 inches minimum in diameter, placed at a maximum spacing of 6 feet on center, and with a minimum embedment length of 7 feet below the bottom of the grade beam. The strength of the concrete and grout should be evaluated by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate sulfate corrosion, as warranted. The design of the grade beam and caissons should be in accordance with the recommendations of the project structural engineer, and include the utilization of the following geotechnical parameters: Creep Zone: 5 -foot vertical zone below the slope face and projected upward parallel to the slope face. Creep Load: The creep load projected on the area of the grade beam should be taken as an equivalent fluid approach, having a density of 60 pcf. For the caisson, it should be taken as a uniform 900 pounds per linear foot of caisson's depth, located above the creep zone. Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive Resistance Passive earth pressure of 300 psf per foot of depth per foot of caisson diameter, to a maximum value of 4,500 psf may be used to determine caisson depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution of the creep prone zone above the point of fixity, to passive resistance, should be disregarded. Allowable Axial Capacity Shaft capacity : 350 psf applied below the point of fixity over the surface area of the shaft. Tip capacity: 4,500 psf. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 File:emp9 \4300 \4306a.pge Page 22 GeoSoils, Inc. DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS The soil materials on site may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that the developer should notify any homeowners or homeowners association of this long -term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content, to a depth of 18 inches below subgrade elevation. If very low expansive soils are present, only optimum moisture content, or greater, is required and specific presoaking is not warranted. The moisture content of the subgrade should be verified within 72 hours prior to pouring concrete. 2. Concrete slabs should be cast over a non - yielding surface, consisting of a 4 -inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. If very low expansive soils are present, the rock or gravel or sand may be deleted. The layer or subgrade should be wet -down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and /or expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid - height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. The exterior slabs should be scored or saw cut, 1 /2 to 3 /s inches deep, often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. Mr. Tim Clancy W.O.4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 23 GeoSoils, Inc. 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi. 6. Driveways, sidewalks, and patio slabs adjacent to the house should be separated from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the house. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. If very low expansion soils are present, footings need only be tied in one direction. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 10. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept in mind that drainage reversals could occur, including post- construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the homeowner or homeowners association. 12. Air conditioning (A/C) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. A/C waste water lines should be drained to a suitable non - erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 F11e:e:wp9 \4300 \4306a.pge Page 24 GeoSoils, Inc. DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out -of -slope direction, after grading. This post- construction movement occurs in two forms: slope creep, and lateral fill extension (LIFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and is anticipated to potentially affect improvements or structures (i.e., separations and /or cracking), placed near the top -of- slope, up to a maximum distance of approximately 15 feet from the top -of- slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located within the creep zone. LIFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long -term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the fill's optimum moisture content. It is generally not practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (per the 1997 UBC and /or California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and /or any homeowners association. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over - watering should be avoided as it can adversely affect site improvements, and cause perched groundwater conditions. Graded slopes constructed utilizing onsite materials would be erosive. Eroded debris may be minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute -type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to develop. A rodent control program to prevent burrowing should be implemented. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 25 GeoSoils, Inc. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over - steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and slopes. Surface drainage should be sufficient to prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should betaken that future landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and /or seep into the ground. In general, the area within 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of 1 percent sloping away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Toe of Slope Drains/Toe Drains Where significant slopes intersect pad areas, surface drainage down the slope allows for some seepage into the subsurface materials, sometimes creating conditions causing or contributing to perched and /or ponded water. Toe of slope /toe drains may be beneficial in the mitigation of this condition due to surface drainage. The general criteria to be utilized by the design engineer for evaluating the need for this type of drain is as follows: • Is there a source of irrigation above or on the slope that could contribute to saturation of soil at the base of the slope? • Are the slopes hard rock and /or impermeable, or relatively permeable, or; do the slopes already have or are they proposed to have subdrains (i.e., stabilization fills, etc.)? Mr. Tim Clancy W.O.4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 26 GeoSoils, Inc. t r • Was the lot at the base of the slope overexcavated or is it proposed to be overexcavated? Overexcavated lots located at the base of a slope could accumulate subsurface water along the base of the fill cap. • Are the slopes north facing? North facing slopes tend to receive less sunlight (less evaporation) relative to south facing slopes and are more exposed to the currently prevailing seasonal storm tracks. • What is the slope height? It has been our experience that slopes with heights in excess of approximately 10 feet tend to have more problems due to storm runoff and irrigation than slopes of a lesser height. • Do the slopes "toe out" into a residential lot or a lot where perched or ponded water may adversely impact its proposed use? Based on these general criteria, the construction of toe drains may be considered by the design engineer along the toe of slopes, or at retaining walls in slopes, descending to the rear of such lots. Following are Detail 4 (Schematic Toe Drain Detail) and Detail 5 (Subdrain Along Retaining Wall Detail). Other drains may be warranted due to unforeseen conditions, homeowner irrigation, or other circumstances. Where drains are constructed during grading, including subdrains, the locations /elevations of such drains should be surveyed, and recorded on the final as -built grading plans by the design engineer. It is recommended that the above be disclosed to all interested parties, including homeowners and any homeowners association. Erosion Control Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over - watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open -bottom planters adjacent to proposed structures be eliminated for a minimum distance of 10 feet. As an alternative, closed -bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetation. Consideration should be given Mr. Tim Clancy W.O.4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 27 GeoSoils, Inc. DETAILS N . T S . SCHEMATIC TOE DRAIN DETAIL 1 c� \oP 2• E Drain May Be Constructed into, or at, the Toe of Slope r r _ Y ' Nettve NOTES: 1.) Soil Cap Compacted to 90 Percent Relative dap Compaction. 12" Minimum 2.) Permeable Material May Be Gravel Wrapped in Filter Fabric (Mirafi 140N or Equivalent). 3.) 4 -Inch Diameter Perforated Pipe (SDR 35 or Equivalent) with Perforations Down. 4.) Pipe to Maintain a Minimum 1 Percent Fall. 5.) Concrete Cutoff Wall to be Provided at Transition Permeable to Solid Outlet Pipe. Material 6.) Solid Outlet Pipe to Drain to Approved Area. 7.) Cleanouts are Recomended at Each Property 24" Line. Minimum Drain Pipe ♦— 12" SCHEMATIC TOE DRAIN DETAIL ! DETAIL 4 Geotechnical • Coastal • Geologic • Environmental DETAILS NT.S 2:1 SLOPE (TYPICAL) TOP OF WALL _ _ _ I BACKFILL WITH COMPATED NOTES: NATIVE SOILS 1.) Soil Cap Compacted to 90 Percent _ _ _ _ _ Relative Compaction. 12" RETAINING WALL _ _ _ _ MIN 2.) Permeable Material May Be Gravel _ _ _ _ _ Wrapped in Filter Fabric (Mirafi 140N or Equivalent). Y 3.) 4 -Inch Diameter Perforated Pipe (SDR -35 of Equivalent) with MIRAFI 140 FILTER FABRIC Perforations Down. FINISHED GRADE OR EQUAL 4.) Pipe to Maintain a Minimum 1 Percent Fall. 3/4" CRUSHED GRAVEL `r 5.) Concrete Cutoff Wall to be Provided WALL FOOTING at Transition to Solid Outlet Pipe. 6.) Solid Outlet Pipe to Drain to Approved Area. 24" 7.) Cleanouts are Recommended at MI 4" DRAIN Each Property Line. 8,) Compacted Effort Should Be h Applied to Drain Rock. 1" TO 2 " 12 SUBDRAIN ALONG RETAINING WALL DETAIL NOT TO SCALE SUBDRAIN ALONG RETAINING WALL DETAIL a DETAIL 5 Geotechnical • Coastal • Geologic • Environmental to the type of vegetation chosen and their potential effect upon surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes or non- erosive devices that will carry the water away from the house. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Site Improvements Recommendations for exterior concrete flatwork design and construction can be provided upon request. If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench, and retaining wall backfills. Tile Flog n4 Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs -on -grade where tile will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 F1e:e:wp9 \4300 \4306a.pge Page 30 GeoSoiils, Inc. (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street and parking areas and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgrade materials would be recommended at that time. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Trenching Considering the nature of the onsite soils, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be anticipated. All excavations should be observed by one of our representatives and minimally conform to CAL -OSHA and local safety codes. Utility Trench Backfill 1. All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12 -inch to 18 -inch) under -slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to verify the desired results. 2. Exterior trenches adjacent to, and within areas extending below a 1:1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to verify the desired results. Mr. Tim Clancy W.O.4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 31 GeoSoils, Inc. 3. All trench excavations should conform to CAL -OSHA and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the structural engineer. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and /or testing be performed by GSI at each of the following construction stages: • During grading /recertification. • During significant excavation (i.e., higher than 4 feet). • During placement of subdrains, toe drains, or other subdrainage devices, prior to placing fill and /or backfill. • After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. • Prior to pouring any slabs or flatwork, after presoaking /presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea - gravel, etc.), or vapor barriers (i.e., visqueen, etc.). • During retaining wall subdrain installation, prior to backfill placement. • During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. • During slope construction /repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. • When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed. • A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and /or to comply with code requirements. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 File:e:wp9 \4300 \4306a.pge Page 32 GeoSoiils, Inc. OTHER DESIGN PROFESSIONALS /CONSULTANTS The design civil engineer, structural engineer, post- tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. In order to mitigate potential distress, the foundation and /or improvement's designer should confirm to GSI and the governing agency, in writing, that the proposed foundations and /or improvements can tolerate the amount of differential settlement and /or expansion characteristics and design criteria specified herein. PLAN REVIEW Final project plans should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and /or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty is expressed or implied. Standards of practice are subjectto change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Mr. Tim Clancy W.O. 4306 -A -SC 2145 Manchester Avenue April 30, 2004 Fi1e:e:wp9 \4300 \4306a.pge Page 33 GeoSoils, Inc. APPENDIX A REFERENCES APPENDIX A REFERENCES Blake, T.F., 2000a, EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3 -D fault sources; Windows 95/98 version. 2000b, EQSEARCH, A computer program for the estimation of peak horizontal acceleration from California historical earthquake catalogs; Updated to June, 2003, Windows 95/98 version. 2000c, FRISKSP, A computer program for the probabilistic estimation of peak acceleration and uniform hazard spectra using 3 -D faults as earthquake sources; Windows 95/98 version. Bozorgnia, Y., Campbell, K.W., and Niazi, M., 1999, Vertical ground motion: Characteristics, relationship with horizontal component, and building -code implications; Proceedings of the SMIP99 seminar on utilization of strong- motion data, September, 15, Oakland, pp. 23 -49. Campbell, K.W. and Bozorgnia, Y., 1997, Attenuation relations for soft rock conditions; in EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3 -D fault sources; Windows 95/98 version, Blake, 2000a. 1994, Near - source attenuation of peak horizontal acceleration from worldwide accelrograms recorded from 1957 to 1993; Proceedings, Fifth U.S. National Conference on Earthquake Engineering, volume III, Earthquake Engineering Research Institute, pp 292 -293. Hart, E.W. and Bryant, W.A., 1997, Fault- rupture hazard zones in California, Alquist - Priolo earthquake fault zoning act with index to earthquake fault zones maps; California Division of Mines and Geology Special Publication 42, with Supplements 1 and 2, 1999. International Conference of building officials, 1997, Uniform building code: Whittier, California, vol. 1, 2, and 3. Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology, map sheet no. 6, scale 1:750,000. Joyner, W.B, and Boore, D.M.,1982a, Estimation of response - spectral values as functions of magnitude, distance and site conditions, in eds., Johnson, J.A., Campbell, K.W., and Blake, T.F.: AEG Short Course, Seismic Hazard Analysis, June 18, 1994. 1982b, Prediction of earthquake response spectra, U.S. Geological Survey Open -File Report 82-977,16p. GeoSoills, Inc. Kennedy, M.P. and Tan S.S., 1996, Geologic maps of the northwest part of San Diego County, California, Division of Mines and Geology, plate 1, scale 1:24,000. Petersen, Mark D., Bryant, W.A., and Cramer, C.H., 1996, Interim table of fault parameters used by the California Division of Mines and Geology to compile the probabilistic seismic hazard maps of California. Sadigh, K., Chang, C. -Y., Egan, J.A., Makdisi, F., and Youngs, R.R., 1997, Attenuation relations for shallow crustal earthquakes based on California strong motion data, Seismological Research Letters, Vol. 68, No. 1, pp. 180 -189. Sadigh, K., Egan, J., and Youngs, R., 1987, Predictive ground motion equations reported in Joyner, W.B., and Boore, D.M., 1988, "Measurement, Characterization, and Prediction of Strong Ground Motion," in Earthquake Engineering and Soil Dynamics II, Recent Advances in Ground Motion Evaluation, Von Thun, J.L., ed.: American Society of Civil Engineers Geotechnical Special Publication No. 20, pp. 43 -102. Sowers and Sowers, 1970, Unified soil classification system (After U. S. Waterways Experiment Station and ASTM 02487 -667) in Introductory Soil Mechanics, New York. Mr. Tim Clancy Appendix A Fi1e:e: \wp9 \4300 \4306a.pge Page 2 GeoSoiis, Inc. APPENDIX B BORING LOGS BORING LOG GeoSoils, Inc. W.O. 4306 -A -SC PROJECT.• TIM CLANCY BORING B -1 SHEET OF 1 2145 Manchester DATE EXCAVATED 4 -15 -04 Sample SAMPLE METHOD: HAND AUGER Standard Penetration Test IR Groundwater _ �, 0 ® Undisturbed, Ring Sample CL Y v a 3 U E D a r m' m y o 2 y Description of Material SM COLLUVIUM/TOPSOIL: @ 0' SILTY SAND, brown, moist, loose. SM TERRACE DEPOSITS: @ V SILTY SAND, orange brown, moist, medium dense to dense w /depth. Total Depth = 4' No Groundwater Encountered Backfilled 4 -15 -2004 5 2145 Manchester GeoSoils, Inc. PLAT B -1 BORING LOG GeoSoils, Inc. W.O. 4306 -A -SC PROJECT.• TIM CLANCY BORING 8-2 SHEET 1 OF 1 2145 Manchester DATE EXCAVATED 4 -15 -04 Sample SAMPLE METHOD: HAND AUGER Standard Penetration Test �Z Groundwater Undisturbed, Ring Sample r yv u� tn� a c o v E Z o o m m W o in Description of Material SM COLLUVIUM/TOPSOIL: s: @ 0' SILTY SAND, brown, damp to moist, loose; roots. s s SM TERRACE DEPOSITS: @ 1' /Z SILTY SAND, orange brown, moist, medium dense to dense w /depth. Total Depth = 4' No Groundwater Encountered Backfilled 4 -15 -2004 5 2145 Manchester GeoSoils Inc. PLAT B-2 GeoSoils, Inc. BORING LOG W.O. 4306 -A -SC PROJECT.- TIM CLANCY BORING B-3 SHEET 1 OF 1 2145 Manchester — DATE EXCAVATED 4 -15 -04 Sample SAMPLE METHOD: HAND AUGER Standard Penetration Test 0 �-Z Groundwater ro o ® Undisturbed, Ring Sample .2 m cE o UE a o m Z).2 m :3 W o 2 Description of Material sM COLLUVIUM/TOPSOIL: CO—) 0' SILTY SAND, brown, damp, loose; roots. SM TERRACE DEPOSITS: @ 1' SILTY SAND, orange brown, moist, medium dense to dense. Total Depth = 3%' No Groundwater Encountered Backfilled 4 -15 -2004 5 2145 Manchester GeoSoils, Inc. PLAT B - BORING LOG GeoSoils, Inc. CVO. 4306 -A -SC PROJECT: TIM CLANCY BORING B SHEET 1 OF 1 2145 Manchester DATE EXCAVATED 4 -15 -04 Sample SAMPLE METHOD: HAND AUGER Standard Penetration Test ;e ® Groundwater c a d C Undisturbed, Ring Sample yv 7u 0 C— � m E m � o m' �= m S > o u, Description of Material SM COLLUVIUM/TOPSOIL: @ 0' SILTY SAND, brown, damp, loose. SM @ 1' /Z SILTY SAND, orange brown, moist, medium dense to dense. s: s: f . w Total Depth = 4' No Groundwater Encountered Backfilled 4 -15 -2004 5 2145 Manchester GeoSoils Inc. PLAT B - 4 APPENDIX C EQFAULT, EQSEARCH, AND FRISKSP EARTHQUAKE RECURRENCE CURVE 2145 Manchester 100 10 L (D Z 1 Cn c m > w ° 1 L a� E Z > .01 E E D U .001 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Magnitude (M) W.O. 4306 -A -SC Plate C - Z o 0 U') H LO N W� ~ O W O C� ° C U Q� OQ LO o H W W � • N a N o O G4 O O 0 o O ° O O o (SJA) poiaad uanja� W.O. 4306 -A -SC Plate C -2 PROBABILITY OF EXCEEDANCE BOZ. ET AL.(1999)HOR PS UNC 1 0 25 yrs 50 yrs 0 0 100 75 yrs 100 rs 90 •-. 80 0 70 -� 60 .n ° 50 a 40 Cu 30 a) U 20 x w 10 0 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Acceleration (q) W.O. 4306 -A -SC Plate C -3 APPENDIX D GENERAL EARTHWORK AND GRADING GUIDELINES GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to filled, placement of fill, installation of subdrains and excavations. The recommendations contained in the geotechnical report are part of the earthwork and grading guidelines and would supercede the provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new recommendations which could supersede these guidelines or the recommendations contained in the geotechnical report. The contractor is responsible forthe satisfactory completion of all earthwork in accordance with provisions of the project plans and specifications. The project soil engineer and engineering geologist (geotechnical consultant) or their representatives should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for conformance with the recommendations of the geotechnical report, the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and observation so that determination may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All clean -outs, prepared ground to receive fill, key excavations, and subdrains should be observed and documented bythe project engineering geologist and /or soil engineer prior to placing and fill. It is the contractors's responsibility to notify the engineering geologist and soil engineer when such areas are ready for observation. Laboratory and Field Tests Maximum dry density tests to determine the degree of compaction should be performed in accordance with American Standard Testing Materials test method ASTM designation D- 1557 -78. Random field compaction tests should be performed in accordance with test method ASTM designation D- 1556 -82, D -2937 or D -2922 and D -3017, at intervals of approximately 2 feet of fill height or every 100 cubic yards of fill placed. These criteria GeoSoiils, Inc. would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. Contractor's Responsibility All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by geotechnical consultants and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction of the soil engineer, and to place, spread, moisture condition, mix and compact the fill in accordance with the recommendations of the soil engineer. The contractor should also remove all major non - earth material considered unsatisfactory by the soil engineer. It is the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the earthwork in accordance with applicable grading guidelines, codes or agency ordinances, and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock, or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material should be removed and disposed of off -site. These removals must be concluded prior to placing fill. Existing fill, soil, alluvium, colluvium, or rock materials determined by the soil engineer or engineering geologist as being unsuitable in -place should be removed prior to fill placement. Depending upon the soil conditions, these materials may be reused as compacted fills. Any materials incorporated as part of the compacted fills should be approved by the soil engineer. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, or other structures not located prior to grading are to be removed or treated in a manner recommended by the soil engineer. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground extending to such a depth that surface processing cannot adequately improve the condition should be overexcavated down to Mr. Tim Clancy Appendix D Fi1e:e: \wp9 \4300 \4306a.pge Page 2 GeoSoils, Inc. firm ground and approved by the soil engineer before compaction and filling operations continue. Overexcavated and processed soils which have been properly mixed and moisture conditioned should be re- compacted to the minimum relative compaction as specified in these guidelines. Existing ground which is determined to be satisfactory for support of the fills should be scarified to a minimum depth of 6 inches or as directed by the soil engineer. After the scarified ground is brought to optimum moisture content or greater and mixed, the materials should be compacted as specified herein. If the scarified zone is grater that 6 inches in depth, it may be necessary to remove the excess and place the material in lifts restricted to about 6 inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report or by the on -site soils engineer and /or engineering geologist. Scarification, disc harrowing, or other acceptable form of mixing should continue until the soils are broken down and free of large lumps or clods, until the working surface is reasonably uniform and free from ruts, hollow, hummocks, or other uneven features which would inhibit compaction as described previously. Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical), the ground should be stepped or benched. The lowest bench, which will act as a key, should be a minimum of 15 feet wide and should be at least 2 feet deep into firm material, and approved by the soil engineer and /or engineering geologist. In fill over cut slope conditions, the recommended minimum width of the lowest bench or key is also 15 feet with the key founded on firm material, as designated by the Geotechnical Consultant. As a general rule, unless specifically recommended otherwise by the Soil Engineer, the minimum width of fill keys should be approximately equal to' /2 the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre - stripping may be considered for unsuitable materials in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas, and the toe of fill benches should be observed and approved by the soil engineer and /or engineering geologist prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations) are attained. COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been determined to be suitable by the soil engineer. These materials should be free of roots, tree branches, other organic matter or other Mr. Tim Clancy Appendix D Fi1e:e: \wp9 \4300 \4306a.pge Page 3 GeoSoiils, Inc. deleterious materials. All unsuitable materials should be removed from the fill as directed by the soil engineer. Soils of poor gradation, undesirable expansion potential, or substandard strength characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other bedrock derived material. Benching operations should not result in the benched material being placed only within a single equipment width away from the fill /bedrock contact. Oversized materials defined as rock or other irreducible materials with a maximum dimension greater than 12 inches should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by the soil engineer. Oversized material should be taken off -site or placed in accordance with recommendations of the soil engineer in areas designated as suitable for rock disposal. Oversized material should not be placed within 10 feet vertically of finish grade (elevation) or within 20 feet horizontally of slope faces. To facilitate future trenching, rock should not be placed within the range of foundation excavations, future utilities, or underground construction unless specifically approved by the soil engineer and /or the developers representative. If import material is required for grading, representative samples of the materials to be utilized as compacted fill should be analyzed in the laboratory by the soil engineer to determine its physical properties. If any material other than that previously tested is encountered during grading, an appropriate analysis of this material should be conducted by the soil engineer as soon as possible. Approved fill material should be placed in areas prepared to receive fill in near horizontal layers that when compacted should not exceed 6 inches in thickness. The soil engineer may approve thick lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than optimum should be watered and mixed, and wet fill layers should be aerated by scarification or should be blended with drier material. Moisture condition, blending, and mixing of the fill layer should continue until the fill materials have a uniform moisture content at or above optimum moisture. After each layer has been evenly spread, moisture conditioned and mixed, it should be uniformly compacted to a minimum of 90 percent of maximum density as determined by ASTM test designation, D- 1557 -78, or as otherwise recommended by the soil engineer. Compaction equipment should be adequately sized and should be specifically designed for soil compaction or of proven reliability to efficiently achieve the specified degree of compaction. Mr. Tim Clancy Appendix D Fi1e:e: \wp9 \4300 \4306a.pge Page 4 GeoSoils, Inc. Where tests indicate that the density of any layer of fill, or portion thereof, is below the required relative compaction, or improper moisture is in evidence, the particular layer or portion shall be re- worked until the required density and /or moisture content has been attained. No additional fill shall be placed in an area until the last placed lift of fill has been tested and found to meet the density and moisture requirements, and is approved by the soil engineer. Compaction of slopes should be accomplished by over - building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special efforts may be necessary to attain the specified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing loose materials with appropriate equipment. Afinal determination of fill slope compaction should be based on observation and /or testing of the finished slope face. Where compacted fill slopes are designed steeper than 2:1 (horizontal to vertical), specific material types, a higher minimum relative compaction, and special grading procedures, may be recommended. If an alternative to over - building and cutting back the compacted fill slopes is selected, then special effort should be made to achieve the required compaction in the outer 10 feet of each lift of fill by undertaking the following: 1. An extra piece of equipment consisting of a heavy short shanked sheepsfoot should be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpendicular to the slopes, and extend out over the slope to provide adequate compaction to the face of the slope. 2. Loose fill should not be spilled out over the face of the slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re- rolling. 3. Field compaction tests will be made in the outer (horizontal) 2 to 8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. 4. After completion of the slope, the slope face should be shaped with a small tractor and then re- rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to verify compaction, the slopes should be grid - rolled to achieve compaction to the slope face. Final testing should be used to confirm compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix and re- compact the slope material as necessary to achieve compaction. Additional testing should be performed to verify compaction. Mr. Tim Clancy Appendix D Fi1e:e: \wp9 \4300 \4306a.pge Page 5 GeoSoils, Inc. 6. Erosion control and drainage devices should be designed by the project civil engineer in compliance with ordinances of the controlling governmental agencies, and /or in accordance with the recommendation of the soil engineer or engineering geologist. SUBDRAIN INSTALLATION Subdrains should be installed in approved ground in accordance with the approximate alignment and details indicated by the geotechnical consultant. Subdrain locations or materials should not be changed or modified without approval of the geotechnical consultant. The soil engineer and /or engineering geologist may recommend and direct changes in subdrain line, grade and drain material in the field, pending exposed conditions. The location of constructed subdrains should be recorded by the project civil engineer. EXCAVATIONS Excavations and cut slopes should be examined during grading by the engineering geologist. If directed by the engineering geologist, further excavations or overexcavation and re- filling of cut areas should be performed and /or remedial grading of cut slopes should be performed. When fill over cut slopes are to be graded, unless otherwise approved, the cut portion of the slope should be observed by the engineering geologist prior to placement of materials for construction of the fill portion of the slope. The engineering geologist should observe all cut slopes and should be notified by the contractor when cut slopes are started. If, during the course of grading, unforeseen adverse, or potential adverse geologic conditions are encountered, the engineering geologist and soil engineer should investigate, evaluate and make recommendations to treat these problems. The need for cut slope buttressing or stabilizing should be based on in- grading evaluation by the engineering geologist, whether anticipated or not. Unless otherwise specified in soil and geological reports, no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractors responsibility. Erosion control and drainage devices should be designed by the project civil engineer and should be constructed in compliance with the ordinances of the controlling governmental agencies, and /or in accordance with the recommendations of the soil engineer or engineering geologist. Mr. Tim Clancy Appendix D Fi1e:e: \wp9 \4300 \4306a.pge Page 6 GeoSoils, Inc. COMPLETION Observation, testing and consultation bythe geotechnical consultant should be conducted during the grading operations in order to state an opinion that all cut and filled areas are graded in accordance with the approved project specifications. After completion of grading and after the soil engineer and engineering geologist have finished their observations of the work, final reports should be submitted subject to review by the controlling governmental agencies. No further excavation or filling should be undertaken without prior notification of the soil engineer and /or engineering geologist. All finished cut and fill slopes should be protected from erosion and /or be planted in accordance with the project specifications and /or as recommended by a landscape architect. Such protection and /or planning should be undertaken as soon as practical after completion of grading. JOB SAFETY General At GeoSoils, Inc. (GSI) getting the job done safely is of primary concern. The following is the company's safety considerations for use by all employees on multi - employer construction sites. On ground personnel are at highest risk of injury and possible fatality on grading and construction projects. GSI recognizes that construction activities will vary on each site and that site safety is the rp ime responsibility of the contractor; however, everyone must be safety conscious and responsible at all times. To achieve our goal of avoiding accidents, cooperation between the client, the contractor and GSI personnel must be maintained. In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented for the safety of field personnel on grading and construction projects: Safety Meetings: GSI field personnel are directed to attend contractors regularly scheduled and documented safety meetings. Safety Vests: Safety vests are provided for and are to be worn by GSI personnel at all times when they are working in the field. Safety Flags: Two safety flags are provided to GSI field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. Mr. Tim Clancy Appendix D Fi1e:e:\wp9 \4300 \4306a.pge Page 7 GeoSoils, Inc. Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing amber beacon, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. Test Pits Location. Orientation and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technicians's safety. Efforts will be made to coordinate locations with the grading contractors authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of current traffic. The contractors authorized representative (dump man, operator, supervisor, grade checker, etc.) should direct excavation of the pit and safety during the test period. Of paramount concern should be the soil technicians safety and obtaining enough tests to represent the fill. Test pits should be excavated so that the spoil pile is placed away form oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non - encroachment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center of the test pit. This zone is established for safety and to avoid excessive ground vibration which typically decreased test results. When taking slope tests the technician should park the vehicle directly above or below the test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractor's representative should effectively keep all equipment at a safe operation distance (e.g., 50 feet) away from the slope during this testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads, cut and fill areas or other factors that may affect site access and site safety. In the event that the technicians safety is jeopardized or compromised as a result of the contractors failure to comply with any of the above, the technician is required, by company policy, to immediately withdraw and notify his /her supervisor. The grading contractors representative will eventually be contacted in an effort to effect a solution. However, in the Mr. Tim Clancy Appendix D Fi1e:eAwp9 \4300 \4306a.pge Page 8 GeoSoils, Inc. interim, no further testing will be performed until the situation is rectified. Any fill place can be considered unacceptable and subject to reprocessing, recompaction or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor brings this to his /her attention and notify this office. Effective communication and coordination between the contractors representative and the soils technician is strongly encouraged in order to implement the above safety plan. Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Our personnel are directed not to enter any excavation or vertical cut which: 1) is 5 feet or deeper unless shored or laid back; 2) displays any evidence of instability, has any loose rock or other debris which could fall into the trench; or 3) displays any other evidence of any unsafe conditions regardless of depth. All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters, should be shored or laid back. Trench access should be provided in accordance with CAL -OSHA and /or state and local standards. Our personnel are directed not to enter any trench by being lowered or "riding down" on the equipment. If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraw and notify his /her supervisor. The contractors representative will eventually be contacted in an effort to effect a solution. All backfill not tested due to safety concerns or other reasons could be subject to reprocessing and /or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner /developer on notice to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify CAL -OSHA and /or the proper authorities. Mr. Tim Clancy Appendix D Fi1e:e:\wp9 \4300 \4306a.pge Page 9 GeoSoiiis, Inc. TEST PIT SAFETY DIAGRAM SIDE VIEW Z S:POIL PILE TEST PIT NOT TO SCALE ) TOP VII 100 FEET LL 50 FEET Lo 50 FIST FLAG SPOIL TEST PIT: ... T:'. PILE FLAG APPROXIMATE CENTER LL OF TEST PIT In I NOT TO SCAT ) PLATE EG--16 m H 0 Z Cf) MANCHESTER AVENUE n a T ru _ N ]o rU rn 3 7 S E SD: 0 ' m 0 3 En i � > m r �(i� t 7 l Tt <� to R) mi to 0 z 0o n1�2 � y n C)� rn 11m� Z�-cr aN < _ o m o m o SJ rn m � t -i N fA D z m r D s Z D D to m rn H � y S 30' 38' 56' E 50.0' - ALLEY f o AC PAVED D m z N Ln '� D ' z rn m D D m En p n © C Z o O 33 s m z ° m m � o c m D m m x Z -i v o m _ F -+ m w N U) � 1.1114 m w cn O ,c� _ i z MANCHESTER AVENUE o 0 co m a n D p --A 3 m 3' rn 0 rn 0 S 34' 3$' ,56' E 50;.0' i -DO Q p D �l —1 O m m 0 i� i 0 i z [^l � z ` j O Z G') as D ~ Z m c w _. m o Z O g �► o - o to m c < I D n 0 �a v w V1 Z CCl ' j �a i D S 30 38' 56' E 50.0' C tL} N ALLEY ru V AC PAVED o m nm m o Q z N Qt PASCO D GDEERDVG (858) 259 -8212 lo t 535 N. HWY 101, STE . 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