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1995-4376 G c:¡j / Ct; ~ --- _._------ u_- --- Category Jf3'ìfo 9 Name --~----------------- _.------- - ---- Street Address I 4(¿L/;¡Lj Serial # Description - -- --..J -- - -, . Plan ck. # Year I I I I I I I I I : I I I I I I I I I I I I / ,/ // / ~ /" "..... ~ /. / ../. /"" ~ " . ------ . . . EXPLANATION: 17 Appoximate Location of Density Test SCALE: 1 INCH = 40 FEET Geotechnics Incorporated SITE PLAN Copper Creek Estates, Lot 8 Bruce D. Weigand, Inc. PROJECT NO. 0007-003-02 DOCUMENT NO. 5-0529 FIGURE 1 I I I I I I I I I I I I I I I I I I I Bruce D. Wiegand, Inc. October 19, 1995 Project No. 0007-003-02 Doc. #5-0529 Page 3 moistures of the soils were determined in the laboratory by ASTM method D1557-91, (Modified Proctor). The on-site fill soils generally consisted of a fine to medium grained sandy clay (CL). In-place moisture and density tests were made in accordance with ASTM D 2922-91 and D 3017- 88 (Nuclear Gauge Method). The results of these tests are tabulated in Figure C-1 in the appendix, "Field Density Test Results". The actual test locations are shown on the Site Plan, Figure 1. The locations and elevations indicated for the tests are based on field survey stakes and estimates from the grading plan topography, and should only be considered rough estimates. The estimated locations and elevations should not be utilized for the purpose of preparing cross sections showing test locations, or in any case, for the purpose of after-the~fact evaluating of the sequence of fill placement. 4.0 GEOTECHNICAL RECOMMENDATIONS The slab subgrade soils include highly expansive sandy clay, as indicated by the test results presented in Figure B-1. The soils were moisture conditioned during grading in order to decrease expansion. However, we recommend that a structurally designed, post-tensioned slab-on~grade be used to mitigate an additional effects of soil expansion. We recommend the following parameters, based on criteria of the Post-Tensioning Institute. Edge Moisture Variation, em Center Lift: Edge Lift: 6.0 feet 3.0 feet Differential Swell, Y m Center Lift: Edge Lift: 5.5 inches 1.1 inches Differential Settlement: 0.5 inches Allowable Bearing Capacity at Slab Subgrade: 2,000 Ibs/fe Geotcchnics Incolvorated I I I I I I I I I I I I I I I I I I I Bruce D. Wiegand, Inc. October 19,1995 Project No. 0007-003-02 Doc. #5-0529 Page 4 5.0 GEOTECHNICAL EVALUATION In our opinion, grading and compaction of the site was peñormed in general accordance with the intent of the project geotechnical recommendations, project specifications, and with the requirements of the City of Encinitas. Based upon our observations and testing, it is our professional opinion that fill soils were placed in substantial accordance with the compaction criteria of 87 percent of the maximum density (ASTM D1557). The conclusions and recommendations contained herein are based on our observations and testing peñormed between October 11 and October 13, 1995. No representations are made as to the quality and extent of materials not observed. 6.0 LIMITATIONS Our services were peñormed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable soils engineers and geologists practicing in this or similar localities. No other warranty, expressed or implied, is made as to the conclusions and professional advice included in this report. The samples taken and used for testing, the observations made, and the in-place field testing peñormed are believed representative of the project; however, soil and geologic conditions can vary significantly between tested or observed locations. This report is issued with the understanding that it is the responsibility of the owner, or of his representative, to ensure that the information and recommendations contained herein are brought to the attention of the architect and engineer for the project and incorporated into the plans, and the necessary steps are taken to see that the contractor and subcontractors carry out such recommendations in the field. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations, and we cannot be responsible for other than our own personnel on the site; therefore, the safety of others is the responsibility of the contractor. The contractor should notify the owner if he considers any of the recommended actions presented herein to be unsafe. Gcotcchnics Inco'1)()mtcd I I I I I I I I I I I I I I I I I I I Bruce D. Wiegand, Inc. October 19, 1995 Project No. 0007-003-02 Doc. #5-0529 Page 5 The findings of this report are valid as of the present date. However, changes in the conditions of a property can occur with the passage of time, whether they be due to natural processes or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of three years. GEOTECHNICS INCORPORATED ~;?~ Anthony F. Belfast, P.E. 40333 Principal AFB/maf Distribution: (4) Addressee Gcotcchnics Incolvol"nted I I I I I I I I I I I I I I I I I I I APPENDIX A REFERENCES American Society for Testing and Materials, 1992, Annual Book of ASTM Standards, Section 4, Construction, Volume 04.08 Soil and Rock: Dimension Stone: Geosvnthetics, ASTM, Philadelphia, PA, 1296 p. Geotechnics Incorporated, July 12, 1995, Geotechnical Update, Lot 8 at Cpoper Creek, Encinitas, California, Project No. 0007-003-00, Doc. #5-0405. Geotechnics Incorporated, July 12, 1995, Post-tensioned slabs, lot 8, Copper Creek Estates, Encinitas, California, Project No. 0007-003-00, Doc. #5-0340. ICG Incorporated, June 8, 1989, Slope stability evaluation, 8 lot subdivision, Lone Jack Road, Encinitas, California, Job No. 04-3867-002-01-00, Log No. 9-1721. Santa Fe Soils, Inc., January 12, 1987, Geologic and soils engineering investigation, 25 acre hillside parcel, Lone Jack Road, Encinitas, California, SF-661. Gcotcchnics Inc(Hvomtcd I I I I I I I I I I I I I I I I I I I APPENDIX B LABORATORY TESTING Selected representative samples of soils encountered were tested using test methods of the American Society for Testing and Materials, or other generally accepted standards. A brief description of the tests peñormed follows: Classification: Soils were classified visually according to the Unified Soil Classification System. Visual classification was supplemented by laboratory testing of selected samples and clas- sification in accordance with ASTM D2487. Maximum Density Optimum Moisture: The maximum density and optimum moisture for representative soil. samples were determined by using test method ASTM D1557, modified Proctor. The test results are summarized in Figure B-1. Expansion Index: The expansion potential of selected soils was characterized by using the test method ASTM D 4829. Figure B-2 provides the results of the tests. Geotcchnics IncOl1>orntcd I I I I I I I I I I I I I I I I I I I MAXIMUM DENSITY TEST RESULTS (ASTM D1557) Sample Description Max. Dry Moisture No. Density Content (pcf) (%) 1 Dark brown fine to medium grained sandy clay (CL). 118.3 13.5 2 Dark arav-brown fine to medium arained sandv clav (CU. 118.7 13.3 EXPANSION TEST RESULTS (ASTM D4829) SAMPLE I I 102 EXPANSION INDEX Sample #2 UBC TABLE NO. 29-C, CLASSIFICATION OF EXPANSIVE SOIL EXPANSION INDEX POTENTIAL EXPANSION 0-20 Very low 21-50 Low 51-90 Medium 91-130 High Above 130 Verv hiah - Laboratory Test Results Copper Creek Estates, Lot 8 Bruce D. Wiegand, Inc. Project No. 0007-003-02 Document No. 5-0529 Figure B-1 Geotechnics Incorporated I I I I I I I I I I I I I I I I I I I APPENDIX C FIELD TEST RESULTS -Elevations and locations of field tests were determined by hand level and pacing relative to field staking done by others. -The precision of the field density test and the maximum dry density test is not exact and variations should be expected. For example, the American Society for Testing and Materials has recently researched the precision of ASTM Method No. D1557 and found the accuracy of the maximum dry density to be plus or minus 4 percent of the mean value and the optimum moisture content to be accurate to plus or minus 15 percent of the mean value; the Society specifically states the "acceptable range of test results expressed as a percent of mean value" is the range stated above. In effect, an indicated relative compaction of 90 percent has an acceptable range of 86.6 to 92.8 percent based on the maximum dry density determination. The precision of the field density test ASTM D1556 has not yet been determined by the American Society for Testing and Materials; however, it must be recognized that it also is subject to variations in accuracy. Geotechnics Incol'pol"ated I I I I I I I I I I I I I I I I I I I Test Test Elevation/ Soil Max. Dry Moisture Dry Relative Required Retest Test No. Date Location Type Density Content Density Compaction Compaction Number Method [ft] [pct] [Ok] [pct] [Ok] [Ok] 1 10/11/95 150 1 118.3 26.2 99.1 84 87 2 NU 2 10/11/95 150 1 118.3 22.1 106.1 90 87 NU 3 10/11/95 151 1 118.3 19.9 107.4 91 87 NU 4 10/11/95 152 1 118.3 23.0 104.8 89 87 NU 5 10/12/95 152 1 118.3 21.8 103.7 88 87 NU 6 10/12/95 152 1 118.3 24.4 105.1 89 87 NU 7 10/12/95 153 1 118.3 25.2 104.1 88 87 NU 8 10/12/95 154 2 118.7 23.8 104.0 88 87 NU 9 10/12/95 154 2 118.7 24.6 103.7 87 87 NU 10 10/13/95 154 2 118.7 24.1 104.9 88 87 NU 11 10/13/95 155 2 118.7 23.2 104.2 88 87 NU 12 10/13/95 156 2 118.7 24.6 101.4 85 87 17 NU 13 10/13/95 156 2 118.7 24.2 102.6 86 87 16 NU 14 10/13/95 156 2 118.7 23.8 101.3 85 87 15 NU 15 10/13/95 156 2 118.7 22.9 104.6 88 87 NU 16 10/13/95 156 2 118.7 23.4 105.2 89 87 NU 17 10/13/95 156 2 118.7 22.1 103.6 87 87 NU LEGEND: AC = Asphaltic Concrete B = Base CG = Curb & Gutter FF = Finish Floor FG = Finish Grade JT = Joint Trench NU = Nuclear Gauge P = Plumbing Tie-In SG = Subgrade SS = Sanitary Sewar CompactionTest Results Copper Creek Estates, Lot 8 Bruce D. Wiegand, Inc. Project No. 0007-003-02 Document No. 5-0529 Figure C-1 Geotechnics Incorporated ~ 08/09/95 09:49 ~ 02/29/1994 05:21 '8'619 942 1327 619-53&-8311 B D WIEGAND INC. GEOTECHNICS INC. - )/l) 002 ,,'p"""ç;' CJ': a'I?- ~ ..p- - P.;r.ciP8lr- Anthony P. BeIrut Mldlael P.ImN;,JÑ) VI. I.- V ancIøhutc August 8, 1895 Bruce D. 'Megand Inc. 1060 Wiegand Street OØvenhain, CA 9202. Project No. 0007.003-00 Ooc. ,5p0405 Attentton: Mr. Bruce Wiegand SUBJECT: Geoteeløllca1IJpda18 lot . .t Copper Crwk E1K1n1ta8. C.øromla REfERENCES: Oeotechnlc5 Incorporated. Juty 12. 1995. Post.(el1sioned stabs. lot 8, cooper Cree It Estates, fnc;n"a~, C.lifomiø. Project No. 0007pOOJ.OO. Dec. 1S-0340. ICG rncorporated. June 8, 1989. Slope stability evaluation, I lot subdivisiors. Lone Jack Road, etlc¡"ifu, Celífomia, Job No. 0.4-3861-002- 01-00. lOO No. 9-1721. Sante Fe Soils, Inc.. JaF1u8fY 12. 1987. Geologic IImJ soils engineering in"-stigatiolt. 25 ac~ hillside PItre'. Lone Jack Road, Eflcinit8$, Califomil. SF-6e1. De. Bruce: As requested. we "eve reviewed the project grøding plans and existing reports for the proposed development of Lot 8 .t Copper Creek Eslates. In our opinion, the reference reports remein applicable to sile de"efopment The geotechnical aspects of the grading plan! conform 10 the reco"""end8tions of the applicable reports. Please call at your eonvenience if you should have any questions regarding this correspondence. We appreciate this opportunity to be of continued setVfce. ~:2 ~~ GEOTECHNICS INCORPORATEO Anthony F. Belfast, P.E" 40333 Prt"eipal P.O. Øox26S00-224 . S8Ø D.c.Jifomia . 92196 Phl)ne (619) 536-1000 . Fu (619) 536-8311 08/09/95 09:48 I- 02/29/1994 05:21 'a'619 942 1327 619-53&-8311 B D WIEGAND INC. GEOTEOiNICS IN(;. 1lJ001 ""A~ tI~ r Geotechnics Incorporate d P.o. Box 26SGO-2¡4 Sa Diep. CA 92196 pboDc; (619) 536-1000 f^,,= (619) 516-8311 LETTER. Of TAAN§MXTIAJL TO: Bruce D. WIegand Inc:. 1050 Wiegand Street Olivenhlin. CA 92024 DATe: August 8, 11'5 ATTENTION: Mr. Bruce Wiegand REGARDING: Lot 8. Copper C...ek GEOTECHNICS PROJ. NO. 0007~OO L w. ... _118m'" the following attached 1Ce,"8 by. FAX X - FAX Ne,: 759-0558 Mal X Messenger - 1n~1udIng nnsmittalld8r Ex"", Mal Client Piek-Up - Number" pa.. FAXed: 2 - CopIH Da.. D__pIon 4 1,.8-95 Geotechnical Update, lot 8 I R,- Pie... ~ if you - any ~ostiol1$' Slgnttl: + any F. Belfast J Copy To: PASCO ENGINEERING, INC. 535 NORTH HIGHWAY 101, SUITE A SOLANA BEACH, CA 92075 (619) 259-8212 FAX (619) 259-4812 . ~,,/ i)L - WAYNE A. PASCO R.C.E. 29577 June 30, 1995 PE 645 City of Encinitas 505 So. Vulcan Avenue Encinitas, CA 92024 Attn: Blair Knoll RE: WIEGAND RESIDENTIAL GRADING PLAN - HYDROLOGY Dear Mr. Knoll: The purpose of this report is to address the surface water runoff as it is impacted by the proposed grading as shown on the grading plan for the above project. The grading project as proposed, is situated on the south side of Wiegand Street, approximately 250 feet west of Lone Jack Road. Wiegand street is a crowned street surfaced with AC, with a 6 inch AC berm at the edge of pavement. The offsite drainage area upstream from the proposed grading consists of approximately 0.15 ac of undeveloped land sloping at 5% grade. Storm runoff is 0.31 cfs at Q100. (See exhibit "B" attached) The proposed pad is drained to the west and to the east. The easterly portion of the pad discharges 0.50 cfs at Q100 while the westerly portion of the pad discharges 0.55 cfs. (See exhibit "B"). This storm water will be discharged onto rip-rap energy dissipators per S.D.R.S.D. D-40 with #2 backing 1.0 feet deep, 5' wide by 5' long, with one layer of filter fabric. The limits of the proposed grading extend to elevation 156. The line of inundation by the 100 year flood is represented on the map as the 155 foot contour perpendicular to the residence. Within the area subject to inundation is a well defined channel. This flowage area conveys approximately 2500 cfs at Q,oo. It is the professional opinion of Pasco Engineering that the drainage system a shown on the grading plan for the Wiegand residence is sufficient to intercept, contain and convey Q,OO to appropriate points of discharge. Also, the grading as proposed will not be impacted by the 100 year line of inundation mentioned above. u [~~ L.. . l~i i. '- JUL 10 1995 E1\!C:if\! r:L fì::\;C: .. C!TY OF ì.3\!CiNni\3 '- HydrologyjPE645 June 30, 1995 Page 2 If you have any questions regarding the above, please do not hesitate to contact us. Very truly yours, PASCO ENGINEERING, INC. 4J~? tÝ~ Wayne Pasco, President RCE 29577 WPjjs Encl: PE 645 HYDROLOGY REPORT FOR LOT 8 - WIEGAND RESIDENCE GRADING PLAN PREPARED BY: PASCO ENGINEERING, INC. 535 NO. HIGHWAY 101, STE. A SOLANA BEACH, CA 92075 (619) 259-8212 JUNE 30, 1995 ¿)~ r~ WAYNE PA CO, REC 29577 (;/30/6) 5 DATE / / . v **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-92 Advanced Engineering Software (aes) Ver. 1.3A Release Date: 3/06/92 License ID 1388 Analysis prepared by: Pasco Engineering, Inc. 535 North Highway 101, suite A Solana Beach, CA. 92075 Ph. (619) 259-8212 fax: (619) 259-4812 ************************** DESCRIPTION OF STUDY ************************** hydrology analysis Wiegand residence * q 100 * Wayne Pasco 6/30/95 * ************************************************************************** FILE NAME: 645.DAT TIME/DATE OF STUDY: 11:12 6/30/1995 --------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: --------------------------------------------------------------------------- 1985 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6-HOUR DURATION PRECIPITATION (INCHES) = SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00 SPECIFIED PERCENT OF GRADIENTS(DEClMAL) TO USE SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED 3.100 FOR FRICTION SLOPE = .9-5 r *************************************************************************** FLOW PROCESS FROM NODE 1.10 TO NODE 1. 00 IS CODE = 21 --------------------------------------------------------------------------- »»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««< --------------------------------------------------------------------------- --------------------------------------------------------------------------- SOIL CLASSIFICATION IS "C" RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4000 INITIAL SUBAREA FLOW-LENGTH = 170.00 UPSTREAM ELEVATION = 164.00 DOWNSTREAM ELEVATION = 156.50 ELEVATION DIFFERENCE = 7.50 URBAN SUBAREA OVERLAND TIME OF FLOW (MINUTES) = *CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED. 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.~7 SUBAREA RUNOFF(CFS) = .31 TOTAL AREA(ACRES) = .15 10.017 TOTAL RUNOFF(CFS) = .31 , . .' , , *************************************************************************** FLOW PROCESS FROM NODE 2.10 TO NODE 2.00 IS CODE = 21 --------------------------------------------------------------------------- »»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««< --------------------------------------------------------------------------- --------------------------------------------------------------------------- SOIL CLASSIFICATION IS "c" RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4000 INITIAL SUBAREA FLOW-LENGTH = 170.00 UPSTREAM ELEVATION = 162.00 DOWNSTREAM ELEVATION = 155.50 ELEVATION DIFFERENCE = 6.50 URBAN SUBAREA OVERLAND TIME OF FLOW (MINUTES) = *CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED. 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.059 SUBAREA RUNOFF(CFS) = .55 TOTAL AREA(ACRES) = .27 10.507 TOTAL RUNOFF(CFS) = .55 *************************************************************************** FLOW PROCESS FROM NODE 3.10 TO NODE 3.00 IS CODE = 21 --------------------------------------------------------------------------- »»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««< --------------------------------------------------------------------------- --------------------------------------------------------------------------- SOIL CLASSIFICATION IS "c" RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4000 INITIAL SUBAREA FLOW-LENGTH = 120.00 UPSTREAM ELEVATION = 161.50 DOWNSTREAM ELEVATION = 155.50 ELEVATION DIFFERENCE = 6.00 URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = *CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED. 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.997 SUBAREA RUNOFF(CFS) = .50 TOTAL AREA(ACRES) = .21 8.072 TOTAL RUNOFF(CFS) = .~o --------------------------------------------------------------------------- --------------------------------------------------------------------------- END OF STUDY SUMMARY: PEAK FLOW RATE(CFS) = TOTAL AREA(ACRES) = .50 .21 Tc(MIN.) = 8.07 --------------------------------------------------------------------------- --------------------------------------------------------------------------- END OF RATIONAL METHOD ANALYSIS .7 ,- * ************************************************************************** HYDRAULIC ELEMENTS - I PROGRAM PACKAGE (C) Copyright 1982-92 Advanced Engineering Software (aes) Ver. 3.1A Release Date: 2/17/92 License ID 1388 Analysis prepared by: PASCO ENGINEERING 535 NORTH HWY 101, SUITE A SOLANA BEACH, CA. 92075 PHONE: (619) 259-8212 FAX (619) 259-4812 - -------------------------------------------------------------------------- TIME/DATE OF STUDY: 11:16 6/30/1995 - -------------------------------------------------------------------------- - -------------------------------------------------------------------------- ************************* DESCRIPTION OF STUDY ************************** * earthen ditch capacity calc * * * * * ************************************************************************* * ************************************************************************** > »PIPEFLOW HYDRAULIC INPUT INFORMATION«« - -------------------------------------------------------------------------- PIPE DIAMETER(FEET) = 1.000 PIPE SLOPE(FEET/FEET) = .0300 PIPEFLOW(CFS) = .31 MANNINGS FRICTION FACTOR = .040000 - -------------------------------------------------------------------------- - -------------------------------------------------------------------------- CRITICAL-DEPTH FLOW INFORMATION: - -------------------------------------------------------------------------- CRITICAL CRITICAL CRITICAL CRITICAL CRITICAL CRITICAL CRITICAL CRITICAL DEPTH (FEET) = .23 FLOW AREA(SQUARE FEET) = .136 FLOW TOP-WIDTH(FEET) = .841 FLOW PRESSURE + MOMENTUM(POUNDS) = FLOW VELOCITY(FEET/SEC.) = 2.281 FLOW VELOCITY HEAD(FEET) = FLOW HYDRAULIC DEPTH(FEET) = FLOW SPECIFIC ENERGY (FEET) = 2.18 .08 .16 .31 - -------------------------------------------------------------------------- - -------------------------------------------------------------------------- NORMAL-DEPTH FLOW INFORMATION: - -------------------------------------------------------------------------- NORMAL DEPTH(FEET) = .27 FLOW AREA(SQUARE FEET) = .17 FLOW TOP-WIDTH(FEET) = .883 FLOW PRESSURE + MOMENTUM(POUNDS) = FLOW VELOCITY(FEET/SEC.) = FLOW VELOCITY HEAD(FEET) = HYDRAULIC DEPTH(FEET) = FROUDE NUMBER = .750 SPECIFIC ENERGY(FEET) = 2.27 1.§53. ---~053 .19 .32 .' . t!)(/ST/NG MANHOlE R/MéZ:/fjii!.9¡¡ 1£ '/5¡¡/7 d.) AVERAGE v OF F:~. -~ 1 \...O\ N\ p.. '? r'.. ,~ ~~ "- \20- \'\ 0. r,~o) "- "- r'3~ " ~ / Ð4t..l1ß 1\ ß " '. J \oUUHI J Ut- :>AN D lEGO DE?ARTMENT OF SANITATION & FLOOD t () \' '..'" \' \ f'.. :'; . ,. i :\ \: . '-20./ ISOPLUVIALS 45' . \ -\" ", ", : \ -, -.....;.. I 15' : ! 33° 451 eo -- .---. - - ~r~;.~d by , u.s. DEPARTMEN1f OF COMMERCE NATJO~AL OC£A!l:IC A."'O AT OSPUERIC AOn'lISTRATION SPECIAL STUOI£S BRA."ICH. OFFICE OF HOROLOGY. NATJONAL WEATHER SERVICE. 301 .... ....' I. » I . 118' I 151 451: f. 30' IS' 117° 45' . 30' 116° " "" - - - COUNTY OF SAN DIEGO ENT OF SANITATION & . flOOD CONTROL 45' ". ~ ~ '.~' .' 30' 15' ,330 45' -- 30' H. >-c , » 118° 45' 30' 15' 11]0 45' 30' IS' 116° I I I \Ñ " .. . . . , ¡ '- . -.--.- .. .. -"-... .. .. . - RUNOFF COEFFICIENTS (RATIONAL METHOD) LAND USE Coefficient, C Soil Group (1) B C .3S ; 40 D .45 Undeveloped Residential: Rura 1 A .30 Single Family ..30 .35 r:v .45 .40 .45 ,SO .55 .45 .50 .60 .70 .45 .50 .55 .65 . iO . ì5 .80 .S5 .80 .85 .90 .95 Multi-Units Mobile Homes (2) Commercial (2) 801'6 Impervious Industrial (2) 90% Impervious NOTES: (1) Obtain soil group from maps on file with the Department of Sanitation and Flood Control. (2) Where actual conditions deviate significantly from the tabulated imperviousness values of 80% or 90%, the values given for coefficien: C, may be revised by multiplying 80% or 90% by the ratio of actual imperviousness to the tabulated imperviousness. However, in no case shall the final coefficient be less than O. SO. For example: C'Jns~ Jer commercial property on 0 soil group. Actual imperviousness = S09ó Tabulated imperviousness = 80% Revised C = ~ X 0.85 = 0.53 8u . APPENDIX! X