1995-4463 G Street Address
Category Serial #
Ll 3 07
Name Description
Plan ck. # Year
recdescv
Geotechnics
Incorporated
Principals:
Anthony F. Belfast
Michael P. Imbriglio
W. Lee Vanderhurst
March 15, 1996
Talbot Custom Building Project No. 0271 - 001 -01
P.O. Box 3029 Doc. #6 -0175
Rancho La Costa, California 92009
Attention: Mr. Steven Jones
SUBJECT: REPORT OF COMPACTION TEST RESULTS
Testing & Observation of Earthwork Construction
Residential Construction, 2950 Wishbone Way
Olivenhain, California
Gentlemen:
This report summarizes the results of the testing and observation services performed by
Geotechnics Incorporated during earthwork construction for the subject residential site. Grading
for this project was conducted by Mike Scott. Our geotechnical services were performed between
February 29, and March 1, 1996.
1.0 PURPOSE AND SCOPE OF SERVICES
This report and the associated geotechnical services were performed in accordance with the
provisions of our proposal number 5 -169, dated December 1, 1995. Field personnel were
provided for this project in order to test and observe site grading, as well as the excavation of
foundations. These observations and tests assisted us in developing professional opinions
regarding whether or not earthwork and foundation construction was conducted in accordance
with the project specifications and geotechnical recommendations. Our services did not include
supervision nor direction of the actual work of the contractor, his employees, nor agents. Our
services did include the following.
• Observation of the preparation of the existing ground in order to determine whether
existing loose surficial soil was removed and compacted in accordance with the
geotechnical recommendations.
P.O. Box 26500 -224 • San Diego California • 92196
Phone (619) 536 -1000 • Fax (619) 536 -8311
Talbot Custom Building Project No. 0271- 001 -01
March 14, 1996 Doc. #6 -0175
Page 2
• Performing suitable field and laboratory tests on fill to support geotechnical
recommendations and conclusions.
• Preparation of daily field reports summarizing the day's activity with regard to earthwork,
and documenting hours spent in the field by our technicians.
• Preparation of this report which summarizes site preparation, field and laboratory test
results, fill placement, and the compaction operations.
2.0 SITE DESCRIPTION
The subject site consists of a single family residential lot on a gently sloping site, as described
previously (Geotechnics Inc, 1995). The residential structure consists of a raised -floor and stem
wall wood framed building. Foundations and floor framing were constructed prior to site grading,
with foundations embedded into the underlying formational materials.
3.0 GRADING OPERATIONS
Grading of the site was performed using typical mass grading techniques with heavy earth - moving
equipment. The surface topsoils were excavated to expose dense formational materials, they
were then moisture conditioned and compacted as recommended in the referenced report. The
equipment used for compaction consisted of a loader, bull- dozer, a wacker, and a water hose.
The maximum densities and optimum moisture contents of selected fill materials are shown in
Figure B -1 of the appendix, "Laboratory Test Results ". The maximum densities and optimum
moistures of the soils were determined in the laboratory by ASTM method D1557 -91, (Modified
Proctor).
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 of 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.
Geotechnics Incogwrated
Talbot Custom Building Project No. 0271 - 001 -01
March 14, 1996 Doc. #6 -0175
Page 3
4.0 GEOTECHNICAL EVALUATION AND RECOMMENDATIONS
Foundations excavations were opserved on December 15, 1995, with excavations exposing dense
Scripps Formation bearing materials. Footings were excavated a minimum of approximately 18
inches below lowest adjacent soil grade. The footings were also stepped in areas where the
foundation grades sloped, with the steps and horizontal runs producing a slope flatter than 2:1
(horizontal: vertical). The subsurface conditions and bearing materials exposed in the footing
excavations were consistent with the conditions described in the referenced geotechnical report.
The foundation bearing soils are considered to be suitable for the support of the planned
residential structure.
In our opinion, grading and compaction of the site was performed 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 90 percent of the maximum density (ASTM D1557). The conclusions and
recommendations contained herein are based on our observations and testing performed between
December 15, 1995, and March 1, 1996. No representations are made as to the quality and
extent of materials not observed.
5.0 LIMITATIONS
Our services were performed 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
performed 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.
Gcotcchnics Incon)orntcd
i
Talbot Custom Building Project No. 0271 - 001 -01
March 14, 1996 Doc. t16 -0175
Page 4
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.
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
61 F
Anthony F. Belfast, P.E. 40333 C 00
Principal
AFB /kws
Geotechnics Incon)orated
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, 1995, "Report of Geotechnical Investigation, Proposed Residential
Construction, 2950 Wishbone Way, Olivenhain, California" October 12, 1995, Project No.
0271 - 001 -00, Doc. #5 -0504
Geotechnics IncorIwated
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 performed 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 -78, modified
Proctor. The test results are summarized in Figure B -1.
Geotcchnics IncorImmted
Sample Description Max. Dry Moisture
No. Density Content
(Pcfl ( %)
1 1 Brown clayey Sand 1 119.9 1 12.0 JI
G e o t e c h n i c s Laboratory Test Results Project No. 0255 - 001 -01
Incorporated 2950 Wishbone Way Document No. 6 -0175
Steve Jones Figure B -1
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 Incorporated
G e o t e c h n i c s DENSITY TEST RESULTS Project No. 0255 - 001 -01
2950 Wishbone Way Document No. 6 -0175
I ncorporated Steve Jones FIGURE C -1
Test Test Elevation Location/ Soil Max. Dry Moisture Dry Relative Required Retest
No. Date [ft] Station Type Density Content Density Compaction Compaction Number
[Pcq N [Pcfl [ %] [ %]
1 2/29/96 335' Fill 1 119.9 14.5 106.5 89 90 2
2 2/29/96 335' Fill 1 119.9 14.8 108.7 91 90
3 2/29/96 337' Fill 1 119.9 13.9 110.8 92 90
4 2/29/96 338' Fill 1 119.9 14.0 107.8 90 90
5 3/1/96 340' Fill 1 119.9 15.1 108.0 90 90
6 3/1/96 342' Fill 1 119.9 15.5 107.7 90 90
7 3/1/96 339' Fill 1 119.9 13.1 109.9 92 90
8 3/1/96 341' Fill 1 119.9 14.4 109.3 91 90
9 3/1/96 343' Fill 1 119.9 12.8 107.9 90 90
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CC)
• Civil Engineering
OOP • Land Planning
• Structural
• Surveying
September 21, 1995
City of Encinitas
Engineering Department
RE: HYDROLOGY EVALUATION FOR THE JONES RESIDENCE
SINGLE FAMILY GRADING PLAN - WISHBONE WAY
PARCEL 4 OF P.M. 14480 - A.P.N. 264 - 221 -40
Gentlemen:
Please allow this letter to serve as an informal hydrology report
for the subject residential grading plan. Based on direct obser-
vations and the attached map and plan, it is my professional
opinion that the drainage for this site is basically the site
itself. It is estimated that the 100 year storm over the graded
portion of the site is approximately 2 CFS.
Our grading plan proposes to intercept the very little drainage
and direct it to Wishbone Way and the existing P.C.C. Brow Ditch
along the frontage of the property. It should be noted that
Wishbone Way is very well maintained along the frontage of this
parcel. The A.C. Pavement and 6 Berms are in excellent condi-
tion and by observation, can easily handle the drainage from the
proposed grading.
Therefore, we request your acceptance of this hydrology evalua-
tion for this project. Should you have any questions or com-
ments, please feel free to contact this office or respond, as
such, with plan check comments.
Sine ly,
LO AN ENGINEER G
7
Douglas Logan, R.C.E. 39726 I,t,;i C 39726
Principal lc! Exp. 12-331-97
* *i
Attachments �q C►V�� �``
��OF C;AL1FnP �
SEP 2 ' 15;;1
132 N. El Camino Real, Suite N • Encinitas, CA 92024
Fax/ Phone 619- 942 -8474
}
Geotechnics
Incorporated
' Principals:
Anthony F. Belfast
Michael P. Imbriglio
October 12, 1995 W. Lee Vanderhurst
'
Talbot Custom Building Project No. 0271 - 001 -00
P.O. Box 3029 Doc. #5 -0504
Rancho La Costa, California 92009
' Attention: Mr. Steven Jones
SUBJECT. REPORT OF GEOTECHNICAL INVESTIGATION
Proposed Residential Construction �3
2950 Wishbone Way OCT 2 5 1995
Olivenhain, California
ENGINEERING SERVICES
' CI OF ENC!NiTAS
Dear Mr. Jones:
' The following report presents the findings, conclusions, and recommendations of our geotechnical
investigation for the planned construction of a residential structure and associated improvements
t at the subject site. In general, our findings indicate that the proposed building site is underlain
by sedimentary bedrock with relatively minor amounts of topsoil overlying the bedrock. There
were no unusual or special conditions apparent in our investigation which would preclude the
' construction as planned; however, some constraints exist which warrant site preparation and
design considerations.
1.0 PURPOSE AND SCOPE OF WORK
The purpose of our investigation was to evaluate existing conditions at the site as they relate to
' the proposed construction, and to provide recommendations regarding foundation design and
earthwork construction. The recommendations contained herein are based on a surface
reconnaissance, subsurface exploration, laboratory testing, and professional experience in the
' general site area. Design values may include presumptive parameters based on professional
judgement. Our scope of work included:
' 1.1 Review of published geologic maps and stereoscopic aerial photographs.
P
P.O. Box 26500 -224 • San Diego California • 92196
Phone (619) 536 -1000 • Fax(619)536-8311
Talbot Custom Building Project No. 0271 - 001 -00
' October 12, 1995 Doc. #5 -0504
Page 2
' 1.2 Field investigation consisting of a visual reconnaissance the surface conditions, the
' logging of three test pits, and the collection of bulk samples for laboratory testing.
1.3 Laboratory testing of samples collected in the field to classify the soil for aid in
determining presumptive engineering properties.
' 1.4 Engineering analysis of field and laboratory data to develop our conclusions and
recommendations.
' 1.5 Preparation of this report.
' 2.0 SITE DESCRIPTION
' The subject site is an undeveloped parcel located along the north side of Wishbone Way in
Olivenhain, California. The rectangular- shaped lot encompasses approximately one acre of land
' in an area generally occupied by residential properties. The approximate configuration of the site
is shown on the attached Site Plan, Plate 1.
The site is situated on a gentle hillside sloping, on average, to the southwest at inclinations
shallower than 10:1 (horizontal to vertical). Elevations at the site range from approximately 333
' feet above mean sea level (MSL) at the southwestern corner of the property, to approximately
352 feet MSL at the northeastern corner of the property. Significant natural drainage courses
' were not observed at the site. Vegetation observed at the site consisted of grasses.
3.0 PROPOSED DEVELOPMENT
' The proposed construction at the site consists of a two -story residence and a concrete driveway.
The structure will have split floor levels roughly following the natural grade of the property.
Anticipated loads for the structures will be typical for light, wood - framed construction.
The site will be graded to establish pads for the structure's floor levels and driveway. Fill slopes
' are anticipated to be less than 5 feet in height and at inclinations of approximately 2:1.
Excavations at the site are anticipated to be generally less than 6 feet in depth.
Ceotechnics Incorporated
Talbot Custom Building Project No. 0271- 001 -00
' October 12, 1995 Doc. #5 -0504
Page 3
' 4.0 GEOLOGY AND SUBSURFACE CONDITIONS
' Based on published geologic maps, and our observations, the site is underlain by sedimentary
bedrock with a mantle of topsoil. The primary sedimentary unit is assigned to the Scripps
' Formation (Tan, 1986). A relatively thin cap of terrace deposit was observed underlying the upper
portion of the site. The approximate distribution of the formational materials are shown on the
' Site Plan, Plate 1. Descriptions of the specific units observed are as follows.
4.1 Scripps Formation
' Formational materials assigned to the Eocene-age Scripps g g Formation were encountered
' in each of the exploratory test pits at depths ranging from two to four feet below the
surface. As observed in the test pits, this material consisted of pale olive brown, weakly
to moderately cemented, silty fine - grained sandstone. Bedding in the sandstone was not
' exposed in the test pits.
' The sandstone is considered generally suitable for the support of structures or fill loads
in its existing condition. The excavations in the sandstone are anticipated to generate
' silty sand. These materials are considered suitable for use in structural fills.
4.2 Terrace Deposits
'
Quaternary -age -a a terrace deposits were encountered in Test Pit No. 1 above elevation 347
p
' MSL. As observed in the test pit, this material consisted of reddish brown, moderately
cemented, clayey fine- to medium - grained sandstone with abundant gravel and cobbles.
The gravel and cobbles were well rounded with clasts observed up to 18 inches in
' dimension.
t The terrace deposit is considered generally suitable for the support of structures or fill
loads in its existing condition. Excavations in this unit are anticipated to generate clayey
sand with abundant gravel and cobbles. These materials are considered generally
' suitable for use in structural fills, with the exception of any clasts greater than 6 inches in
dimension.
Geotechnics Incorporated
Talbot Custom Building Project No. 0271- 001 -00
' October 12, 1995 Doc. #5 -0504
Page 4
' 4.3 Topsoil
' Topsoil was also encountered in each of the test pits and appeared to mantle much of the
site. As observed in the test pits, the topsoil was generally two feet thick, and consisted
' of brown to reddish brown, silty sand and clayey sand with gravel. The gravel was well
rounded and included some cobbles. The topsoil was generally dry to moist and loose.
' Portions of the topsoil were critically expansive based on laboratory testing. The topsoil
encountered in Test Pit No. 1 and Test Pit No. 2 consisted of clayey sand. The clayey
' sand exhibited an expansion index of 143 which is considered very high.
' The topsoil is not considered, in its present state, suitable for the direct support of
structural loads. In addition, this material may not be suitable for use in fills directly
underlying proposed improvements due to its critical expansion potential.
4.4 Groundwater
' Groundwater was not observed in the test pits and surface seepage was not observed at
the site. Given the topography of the site, shallow groundwater or seepage, is not
anticipated to occur; however, changes in rainfall, irrigation, site drainage, or an on -site
septic system could produce areas of perched groundwater, or changes in the existing
' groundwater level.
' 5.0 GEOLOGIC HAZARDS AND SEISMICITY
The subject site is not located within an area previously known for significant geologic hazards.
' There are no known active faults underlying the site nor was any evidence of past soil failures
or landslides noted during our investigation.
1 The nearest known active fault Is the Rose Canyon fault zone which is located approximately 6
' miles west of the site. Assuming a maximum probable earthquake magnitude of 6.4 (Treiman,
1984), the estimated peak ground acceleration for the site would be 0.30g based on attenuation
curves by Mualchin and Jones (1992). Design of the structures should comply with the
' requirements of the governing jurisdictions, building codes and standard practices of the
Association of Structural Engineers of California.
Geotechnics Incorporated
Talbot Custom Building Project No. 0271 - 001 -00
' October 12, 1995 Doc. #5 -0504
Page 5
' 6.0 CONCLUSIONS AND RECOMMENDATIONS
' Our investigation did not uncover any geotechnical conditions which would preclude the proposed
residential construction. The proposed development is considered feasible from a geotechnical
' standpoint provided sound construction practices and the recommendations contained in this
report are incorporated. The primary geotechnical aspects of the proposed development include
the following:
• There are no known active faults, slope instabilities, or other geologic hazards underlying
' the subject site. The nearest known active fault is associated with the Rose Canyon fault
zone which is located approximately 6 miles west of the site.
• The site is underlain by sedimentary bedrock with a relatively thin mantle of topsoil at the
surface. The bedrock possesses excellent bearing capabilities, however, the topsoil is
' compressible and not considered suitable for the direct support of structural loads because
of its settlement potential and its very high expansive characteristics.
' Excavations at the site should generally produce granular materials suitable for use in
structural fills; however, portions of the topsoil material are considered critically expansive.
' The expansive materials should be excavated and removed from improvement areas, and
should not be used in fills directly beneath proposed improvements. Some oversize
' materials may also be generated from the excavations that will require special handling.
• A review of the grading plan indicated that a portion of the structure will be founded on
' formational material (cut area), and a portion will be underlain be fill. Structures that
straddle cut -fill transitions may be subject to adverse differential settlement. We therefore
' recommend that the cut areas be over - excavated so that the structure is underlain be a
relatively uniform depth of fill.
' As an alternative to the removal of topsoil, and the over - excavation of cut -fill transitions,
the structure may be supported on foundations extending into formational materials, and
a raised wood floor utilized. Based on the grading plans reviewed, it appears that the
garage will be located in formational material due to the depth of cut proposed. A
t concrete on -grade slab should therefore be suitable in this area.
' Geotcchnics Incorporated
Talbot Custom Building Project No. 0271 - 001 -00
' October 12, 1995 Doc. #5 -0504
Page 6
t The remainder of this report presents recommendations regarding the geotechnical aspects of
' the project. These recommendations are based on empirical and analytical methods typical of
the standard of practice in southern California. If these recommendations appear not to cover
any specific feature of the project, please contact our office for additions or revisions to the
recommendations.
' 6.1 Excavation and Grading Observation
Foundation excavations and site grading excavations should be observed by Geotechnics
Incorporated. During grading, Geotechnics Incorporated should provide observation and
testing services continuously. Such observations are considered essential to identify field
' conditions that differ from those anticipated by the preliminary investigation, to adjust
designs to actual field conditions, and to determine that the grading is accomplished in
general accordance with the recommendations of this report. The recommendations
' presented in this report are contingent upon Geotechnics Incorporated performing such
services. Our personnel should perform sufficient testing of fill during grading to support
' our professional opinion as to compliance with compaction recommendations.
6.2 Site Preparation
6.2.1 Alternative A: On -Grade Slabs and Conventional Foundations
' In all areas of lanned construction, an vegetation, roots or other deleterious
P Y 9 ,
' material which may exist should be removed and hauled off -site. Site preparation
should include the removal of the topsoil in areas proposed for building pads,
flatwork, or driveway areas. Removal of the existing topsoil should be made to
expose competent bedrock materials. Based on the conditions observed in the
test pits, the depth of removals are anticipated to be generally on the order of 2
' feet. The geotechnical consultant should observe the removals during
construction. Because of the very highly expansive nature of the topsoil, these
materials should not be incorporated in fills beneath improvement.
To decrease the potential for cracking or distress related to transitions from
bedrock to compacted fill, it is recommended that the structure be founded on a
relatively uniform depth of compacted fill. The bedrock portion(s) of the building
' pads should be over - excavated so that at least three feet of compacted fill, as
Geotechnics Incorporated
Talbot Custom Building Project No. 0271- 001 -00
October 12, 1995 Doc. #5 -0504
Page 7
' measured from planned subgrade, will exist beneath the structure. Site removals
and re- compaction for both loose soils and transitions should extend beyond the
perimeter of the proposed structures and fill areas at a projected 1:1 plane, or to
a minimum horizontal distance of 5 feet. Backfilling of the excavation should be
' as recommended in Section 6.3.
' 6.2.2 Alternative B: Raised Wood Floor and Foundations in Bedrock
If foundations are deepened as required so that they bear in formational materials,
' and if a raised structural slab is used over fill or topsoil areas, then no special site
preparation is considered necessary in the building area. However, normal
' clearing and grubbing should be performed.
6.3 Fill Compaction
Expansive materials should not be placed directly beneath the proposed improvements.
' Highly expansive materials should be kept at a depth of at least 5 feet below the proposed
improvements, and at a minimum horizontal distance of 5 feet.
' All fill and backfill to be placed in association with site development should be accom-
plished at slightly over optimum moisture conditions and compacted using equipment that
' is capable of producing a uniform product. The minimum relative compaction
recommended for fill is 90 percent of the maximum density based on ASTM D1557 -91
' (modified Proctor). Rocks placed in the compacted fill should be no larger than 6 inches
in largest dimension, with the rock placed separately to avoid 'nesting' or voids around the
rock. Sufficient observation and testing should be performed by Geotechnics Incorporated
' so that an opinion can be rendered as to the compaction achieved.
' Imported fill, if used, should be observed prior to hauling onto the site to determine the
suitability for use. Representative samples of imported materials and on site soils should
be tested by the geotechnical consultant in order to evaluate their appropriate engineering
' properties. Imported soil should have an expansion index of 20 or less.
' During grading operations, soil types other than those analyzed during this investigation
may be encountered by the contractor. The geotechnical consultant should be notified
' to evaluate the suitability of these soils for use as fill and as finish grade soils.
Geotechnics incorporated
Talbot Custom Building Project No. 0271 - 001 -00
' October 12, 1995 Doc. #5 -0504
Page 8
' 6.4 Slope Stability
' The planned cut and fill slopes should be constructed at inclinations of 2:1 or flatter. Fill
slopes should be founded on firm bedrock, and where the natural ground surface slopes
' greater than 5:1 (horizontal: vertical), it should be benched to produce a level area to
receive the fill. Benches should be wide enough to provide complete coverage by the
' compaction equipment. The construction of compacted fill slopes should be performed
in accordance with section 6.3, Fill Compaction. The slope faces should be compacted
to the recommended 90 percent relative compaction, either by rolling with a sheepsfoot
' roller or other suitable heavy equipment, or by overfilling the slope and cutting back to
design grade.
6.5 Site Drainage
' Foundation and slab performance depends greatly on how well the runoff waters drain
from the site. This is true both during construction and over the entire life of the structure.
' The ground surface around structures should be graded so that water flows rapidly away
from the structures without ponding. The surface gradient needed to achieve this depends
' on the prevailing landscape. In general, we recommend that pavement and lawn areas
within five feet of buildings slope away at gradients of at least two percent. Densely
vegetated areas should have minimum gradients of at least five percent away from
' buildings in the first five feet. Densely vegetated areas are considered those in which the
planting type and spacing is such that the flow of water is impeded.
' Planters should be built so that water from them will not seep into the foundation, slab,
or pavement areas. Site irrigation should be limited to the minimum necessary to sustain
' landscaping plants. Should excessive irrigation, surface water intrusion, water line breaks,
or unusually high rainfall occur, saturated zones or "perched" groundwater may develop
' in the underlying soils.
' 6.6 Foundation Recommendations
These recommendations are considered generally consistent with methods typically used
' in southern California. Other alternatives may be available. The foundation
recommendations herein should not be considered to preclude more restrictive criteria of
governing agencies or by the structural engineer. The design of the foundation system
Geotechnics Incorporated
Talbot Custom Building Project No. 0271 - 001 -00
' October 12, 1995 Doc. #5 -0504
Page 9
' should be performed by the project structural engineer, incorporating the geotechnical
' parameters described in the following sections.
The following design parameters assume that the all foundations will bear on compacted
' fill materials that were prepared as previously described, or extended so that they all bear
on undisturbed formational material. Conventional foundations can consist of continuous
' footings or isolated footings or piers.
6.6.1 Foundations in Compacted Fill:
Allowable Soil Bearing: 2,000 psf (allow a one -third increase for short -term
' wind or seismic loads)
Minimum Footing Width: 12 inches
t Minimum Footing Depth: 18 inches below lowest adjacent soil grade
Minimum Reinforcement: Two no. 4 bars at both top and bottom in continuous
' footings.
6.6.2 Foundations in Formational Material:
' Allowable Soil Bearing: 3,000 psf (allow a one -third increase for short-term
wind or seismic loads)
Minimum Footing Width: 12 inches
t Minimum Footing Depth: 18 inches below lowest adjacent soil grade and 6
inches into undisturbed formational material
' Minimum Reinforcement: Two no. 4 bars at both top and bottom in continuous
footings.
' 6.6.3 Lateral Resistance:
Lateral loads against structures may be resisted by friction between the bottoms
' of footings or slabs and the supporting soil. A coefficient of friction of 0.35 is
recommended. Alternatively, a passive pressure of 350 pcf is recommended for
the portion of vertical foundation members embedded Into compacted or
formational soil. If friction and passive pressure are combined, the passive
' pressure value should be reduced by one - third.
Gcotechnics Incorporated
Talbot Custom Building Project No. 0271 - 001 -00
October 12, 1995 Doc. #5 -0504
Page 10
' 6.6.4 Settlement
' Settlement resulting from the bearing loads recommended are not expected to
exceed 3/4 -inch and 1/2 -inch, respectively for total and differential settlements
' across the length of the proposed structures.
' 6.7 Interior On -Grade Slabs
Slabs should be designed for the anticipated loading. If an elastic design is used, a
' modulus of subgrade reaction of 250 kips /ft should be suitable. As a minimum, slabs
should be at least 5 inches in thickness and be reinforced with at least #3 bars on 24 -inch
' centers, each way.
' Concrete slabs constructed on soil ultimately cause the moisture content to rise in the
underlying soil. This results from continued capillary rise and the termination of normal
evapotranspiration. Because normal concrete is permeable, the moisture will eventually
' penetrate the slab unless some protection is provided. To decrease the likelihood of
problems related to damp slabs, suitable moisture protection measures should be used
' where moisture sensitive floor coverings or other factors warrant. A commonly used
moisture protection consists of about four inches of clean sand covered by 'visqueen'
plastic sheeting. In addition, two inches of sand are placed over the plastic to decrease
concrete curing problems associated with placing concrete directly on an impermeable
membrane. However, it has been our experience that such systems will transmit from
approximately 6 to 12 pounds of moisture per 1000 square feet per day. This may be
' excessive for some applications.
' If more protection is needed, we recommend that the slab be underlain by at least 6-
inches of minus 3/4 -inch crushed rock, with no plastic membrane. In addition, it is
' recommended that a low water - cement ratio concrete (0.5 maximum) be used and that
the slab be moist -cured for five to seven days in accordance with guidelines of the
American Concrete Institute. On -site quality control should be used to confirm the design
conditions.
Gcotcchnics Incorporated
Talbot Custom Building Project No. 0271 - 001 -00
' October 12, 1995 Doc. #5 -0504
Page 11
6.8 Reactive Soils
' Because of the likelihood that the sulfate content of the on -site soil or groundwater is
sufficient to react adversely with normal cement, we recommend that Type II cement be
' used in all concrete which will be in contact with soil.
' 6.9 Earth Retaining Structures
Expansive clay should not be used in retaining wall backfill. Cantilever retaining walls
' backfilled with on -site soil should be designed for an active earth pressure approximated
by an equivalent fluid pressure of 35 Ibs /ft The active pressure should be used for walls
' free to yield at the top at least 0.2 percent of the wall height. For walls restrained so that
such movement is not permitted, an equivalent fluid pressure of 45 Ibs /ft should be used,
' based on at -rest soil conditions. The above pressures do not consider any sloping
backfill, surcharge loads, or hydrostatic pressures. If these are applicable, they will
increase the lateral pressures on the wall and we should be contacted for additional
' recommendations.
' Retaining wall backfill should be compacted to at least 90 percent relative compaction,
based on ASTM D1557 -91. Backfill should not be placed until walls have achieved
adequate structural strength. Heavy compaction equipment which could cause distress
' to walls should not be used.
' 7.0 LIMITATIONS OF INVESTIGATION
This investigation was performed using the degree of care and skill ordinarily exercised, under
similar circumstances, by reputable geotechnical consultants practicing in this or similar localities.
No other warranty, expressed or implied, is made as to the conclusions and professional opinions
' included in this report.
The samples taken and used for testing and the observations made are believed representative
' of the project site; however, soil and geologic conditions can vary significantly between borings.
' As in most projects, conditions revealed by excavation may be at variance with preliminary
findings. If this occurs, the changed conditions must be evaluated by the geotechnical consultant
' and additional recommendations made, if warranted.
Gcotechnics Incorporated
Talbot Custom Building Project No. 0271 - 001 -00
' October 12, 1995 Doc. #5 -0504
Page 12
t This report is issued with the understanding that it is the responsibility of the owner, or of his
P P Y ,
' representative, to ensure that the information and recommendations contained herein are brought
to the attention of the necessary design consultants for the project and incorporated into the
plans, and the necessary steps are taken to see that the contractors carry out such recommenda-
tions in the field.
' The findings of this report are valid as of the present date. However, changes in the condition
of a property can occur with the passage of time, whether due to natural processes or the work
of man on this or adjacent properties. In addition, changes in applicable or appropriate standards
' of practice may occur 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 o Q ®F ; g` W. Lee Vanderhurst, C. 5
' Principal t�' ��ONY E 6 Principal �ED �
AFB /WLV /dr N0� 0040333f � W. LEE CN
' VANDERHURST �{
No. 1125
Distribution: (3) Addressee 0 . CIVA. • CERTIFIED •
Lp ENGINEERING
Q
q� GEO OG
Attachments: Appendix A - References
F O
Appendix B - Test Pit Logs nJ� r , ,
Appendix C - Laboratory Test Results
' Plate 1 - Site Plan
1
Gcotcchnics Incorporated
t
' 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; Geosynthetics: Philadelphia,
PA, 1296 p.
Bowles, J.E. 1988, Foundation Analysis and Design: 4th ed., New York, McGraw Hill, 816 p.
' California Division of Mines and Geology, 1975, Recommended Guidelines for Determining the
' Maximum Credible and the Maximum Probable Earthquakes: California Division of Mines
and Geology Notes, Number 43.
' California Department of Conservation, Division of Mines and Geology, 1993, The Rose Canyon
Fault Zone, Southern California: Division of Mines and Geology, Open File Report 93 -02.
' Jennings, C.W., 1994, Fault Map of California: California Department of Conservation, Division
of Mines and Geology, California Geologic Data Map Series, Map No. 6.
Mualchin, L., and Jones, A.L., 1982, Peak Accelerations from Maximum Credible Earthquakes
' in California (Rock and Stiff Soil Sites): California Division of Mines and Geology, Open -
File Report 92 -1.
' Tan, S.S., 1986, Landslide Hazards in the Rancho Sante Fe Quadrangle, San Diego County,
California: California Division of Mines and Geology, Open -File Report 86 -15 LA, Landslide
' Hazard Identification Map No. 6, Plate 6C.
' Treiman, J.A., 1984, The Rose Canyon Fault Zone, A Review and Analysis: California Division
of Mines and Geology.
' United States Department of Agriculture, 1953, Aerial Photographs: Flight AXN -4M, Photos 72
and 73, dated March 31.
1
' APPENDIX B
' FIELD EXPLORATION
' Field exploration consisted of a visual reconnaissance of the site and subsurface exploration.
Three test pits were excavated by Talbot Custom Building. The test pits were excavated to a
' maximum depth of 5 -1/2 feet. Bulk samples were collected from excavated soils. The
approximate locations of the test pits are shown on Plate 1. Logs describing the subsurface
conditions encountered are presented as Figures B -1 and B -2.
Test pit locations were approximately located using the plans provided for the proposed
' development. The locations shown should not be considered more accurate than is implied by
the method of measurement used. The lines designating the interface between soil and rock
' material on the test pit logs are determined by interpolation and are therefore approximations.
The transition between the materials may be abrupt or gradual. Further, soil and rock conditions
at locations between the test pits may be substantially different from those at the specific
' locations explored. It should be recognized that the passage of time can result in changes in the
soil conditions reported in our logs.
1
LOG OF EXPLORATION TEST PIT NO. 1
' Logged by: DR Date: 10/5/95
Method of Excavation: Backhoe with 24 -inch bucket Elevation: 351 ft
DEPTH DESCRIPTION LAB TESTS
TOPSOIL: Brown silty SAND (SM) with gravel, fine to medium grained, dry Sieve Analysis
1 ft. to moist, loose.
TERRACE DEPOSITS: Reddish brown clayey SANDSTONE with gravel and
3 ft* cobble, fine to medium grained, dry to moist, moderately
' cemented, clasts up to approximately 18 inches in dimension.
4 ft.
SCRIPPS FORMATION: Pale olive gray, silty SANDSTONE, fine grained,
' 5 ft. moist, weakly to moderately cemented, iron -oxide staining.
6 ft.
Total Depth: 5 -1/2 feet
' 7 ft. No groundwater encountered
No caving
8 ft.
' 9 ft.
10 ft.
LOG OF EXPLORATION TEST PIT NO. 2
' Logged by: DR Date: 10/5/95
Method of Excavation: Backhoe with 24 -inch bucket Elevation: 347 ft
' DEPTH DESCRIPTION LAB TESTS
TOPSOIL: Brown clayey SAND (SC) with some gravel, fine grained, dry to
1 ft. moist, loose.
SCRIPPS FORMATION: Olive gray silty SANDSTONE, fine grained, moist, Sieve Analysis
3 ft, weakly to moderately cemented, iron -oxide staining.
' 4 ft.
' 5 ft. Total Depth: 4 feet
No groundwater encountered
6 ft. No caving
7 ft.
8 ft.
9 ft.
10 ft.
t
PROJECT NO. 0271 - 001 -00 GEOTECHNICS INCORPORATED FIGURE: B -1
LOG OF EXPLORATION TEST PIT NO. 3
' Logged by: DR Date: 10/5/95
Method of Excavation: Backhoe with 24 -inch bucket Elevation: 341 ft
' DEPTH DESCRIPTION LAB TESTS
TOPSOIL: Reddish brown clayey SAND (SC) with few gravel, fine grained, Sieve Analysis
1 ft. dry, to moist, loose. Expansion Index
SCRIPPS FORMATION: Olive gray silty SANDSTONE, moist, moderately
' 3 ft, cemented, iron -oxide staining.
4 ft.
5 ft.
6 ft. Moderately to intensely weathered, difficult to excavate
Total Depth: 6.7 feet
8 ft. No groundwater encountered
No caving
9 ft. Backfilled on 7/13/95
' 10 ft.
' PROJECT NO. 0271- 001 -00 GEOTECHNICS INCORPORATED FIGURE: B -2
APPENDIX C
' LABORATORY TESTING
Samples typical of the soils encountered were selected for laboratory testing. Testing was
performed in accordance with methods of ASTM or other commonly accepted methods.
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 -90. The soil classifications are shown on the test pit
logs.
Particle Size Analysis Particle size analyses were performed in accordance with ASTM D422 -63.
The grain size distribution was used to determine presumptive strength parameters and to
develop foundation design criteria. The results are provided on the following Figures C -1 through
' C -3.
Expansion Index: The expansion potential of selected soils was characterized by using ASTM
' test method D4829. Figure C -4 provides the results of the tests.
t
' APPENDIX C
LABORATORY TESTING
' Samples typical of the soils encountered were selected for laboratory testing. Testing was
performed in accordance with methods of ASTM or other commonly accepted methods.
' 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 -90. The soil classifications are shown on the test pit
logs.
' Particle Size Analysis Particle size analyses were performed in accordance with ASTM D422 -63.
The grain size distribution was used to determine presumptive strength parameters and to
' develop foundation design criteria. The results are provided on the following Figures C -1 through
C -3.
Expansion Index: The expansion potential of selected soils was characterized by using ASTM
test method D4829. Figure C -4 provides the results of the tests.
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' EXPANSION TEST RESULTS
' (ASTM D4829)
' SAMPLE EXPANSION INDEX EXPANSION POTENTIAL
Test Pit No. 3 @ 0' -2' 143 VERY HIGH
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 Vizry hi h
' i =6_G e o t e c h n i c s Laboratory Test Results Project No. 0271 - 001 -00
Incorporated 2950 Wishbone Way Document No. 5 -0504
Olivenhain, California Figure No. C -4