HomeMy WebLinkAboutTract Map 9833-1 Lot 8 Soil & Foundation Report
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SOIL AND FOUNDATION INVESTIGATION REPORT
PROPOSED SINGLE FAMILY RESIDENCE
,
LOT 8 OF TRACT 9833-1
PIASANO PLACE. RANCHO SANTIAGO
TEMECULA. CtLIFORNIA
FOR
GLENN AND PAT CROWTHER
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PROJECT NO. 96-032.PI
DATED AUGUST 25. 1997
Lakeshore Engineering
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LAKESHORE
Engineering
Consulting Civil Engineering and Geologists
August 25, 1997
Project No. 96-032.PI
Client: Glenn and Pat Crowther
45539 Corte Narbonne
Temecu1a, CA 92592
(909) 676-3394 Home 371-3390 Office
Attention: Glenn and Pat Crowther
Subject: Soil and Foundation Investigation Report
Proposed Single Family Residence
Lot 8 of Tract 9833-1, Rancho Santiago
Temecula, California
Gentlemen:
INTRODUCTION
This report presents the findings and conclusions of a soil and
foundation investigation for the proposed development of a single
family residence to be located at the subject site. The purpose of our
site investigation was to 1) evaluate the foundation materials,
subsurface and general geologic conditions at the site, and 2) provide
pertinent foundation recommendations for a proposed single family
residential development. I
Our investigation included the folloring scope of work:
1) Performed two exploratory tr~nches on the lot to
determine subsurface conditi ns, and collect representative
soil samples for laboratory, esting (Appendix A).
2) Laboratory testing of a repr~sentative soil sample to
evaluate the engineering pro~erties. Laboratory test results
are presented in Appendix B.!
3) Engineering analyses for foundation and necessary earthwork.
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4) General geology and seismici~y in the area and the
preparation of this report.
PROPOSED DEVELOPMENT
Base on review of foundation plans made available to us, the proposed
development will consist of a two ~tory single family residence of
conventional woodframe construction, 'supported on spread footings. The
house will be founded on a graded/engineered pad with associated front
driveway and landscape areas. A neference grading plan has been
prepared by Lakeshore Engineering, dated July 15, 1996 (P.N. 96-
032.GP).
31606 Railroad Canyon Road, #201 . Canyon Lake, CA 92587 . (909) 244-2913 . FAX: (909) 244-2987
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LOCA TION MAP
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LAKESHORE
Engineering
PROPOSED RESIDENCE
GLENN & PAT CROWTHER
PIASANO PLACE
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CONSULTING CIVIL ENGINEERS
Project No:
97-032.PI
Dote
8/25/97
Figure No:
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TOPOGRAPHIC MAP
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LAKESHORE
Engineering
PROPOSED RESIDENCE
GLENN & PAT CROWTHER
PIASANO PLACE
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CONSULTING CIVIL ENGINEERS
Project No:
97-032.PI
Dote
8/25/97
FIgure No:
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August 25, 1997
Project No: 96-032.PI
Page Two
SITE INVESTIGATION
The site investigation consisted of a visual site reconnaissance,
subsurface backhoe exploration and engineering analysis of field data
and laboratory test results. A description of the field investigation,
as well as exploratory trench log~, are presented in Appendix A.
Resul ts of the laboratory test datp. are included in Appendix B. A
description of the site and condition~ encountered are presented below.
!
SITE DESCRIPTION
The subject lot is located approximately 2 miles east of the Temecula,
Old Town center. The native terrain here lies near the SW end of the
Hog Back country that typifies sections east of Temecula. In this area,
the topography takes the form of a pronounced series of low, broad-
backed, NE-SW, trending ridges. Relief is usually not much more than
100 feet. However, slopes may be moderately steep and drainages,
incised. At the site, the area is part of a new, upper scale, ranch-
style neighborhood. The property, 'i tself, is located on a NE-SW,
trending ridge crest, flanking a SE-facing slope of about 35% and a
height of about 100 feet. The existing "show pad" area, adjacent to the
street and will be enlarged into a transitional cut/fill building site.
The proposed pad elevation (1196.0) will be approximately at the same
elevation of the street at the northwesterly corner of the lot.
!
Existing surface drainage is by sheetflow, along the natural hillside
(3:1-H:V). The ridge top setting of t~is property provides views of the
mountainous regions, which lies on '2' sides -- to the east, the San
Jacinto, and to the south, the Agua ~ibia.
Ground cover consists of a heavy growth of annual grasses. The lot is
clear of any trash or garbage. No active drainage cross the property.
The ground surface is smooth and uniform with no incise drainage
(erosion) along the hillside.
SUBSURFACE CONDITIONS
A total of two exploratory trenches were performed to a maximum depth
of 7 feet. Location of exploratory tr~nches are shown on the plot plan,
figure 1.
Based on our exploratory findings, the proposed building pad area is
underlain by native granular Silty SAND/Sandstone. In trench T-1 the
upper 3 feet consist of man-made fills. In T-2 the upper 5 feet is
fills. The subsurface fill dirt are light yellowish brown, relatively
dry and loose. Clay is lacking. The ~ative Sand/Sandstone is dense.
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Lakeshore Engineering
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August 25, 1997
Project No: 96-032.PI
Page Three
GENERAL GEOLOGY
The rough graded crest in this area is directly underlain by the Pauba
Sandstone, of Pleistocene age. The Pauba sandstone is usually an
indurated, grayish yellow, silty, finer grain sandstone.
SEISMICITY
The site is located about 3/4-mile east of the active Wildomar Fault
strand of the Elsinore Fault Zone. Copsequently, the setting is acutely
seismic. Most recent consideration (DMG O.F. 92-1) give the Elsinore
Fault Zone a seismic rating of 7 1/2. Accompanying maps, prepared for
internal use by Calstrans indicate that the site may experience a
maximum credible earthquake, which could generate peak accelerations of
0.6g. Therefore, repeatable acceleration may approach 0.4g.
The ridge top setting, up to 100 feet above drainage, precludes most
secondary affects of possible earthquakes. Rocks, liquefactions, and
flooding should not be a problem,. Ho~ever, ridge-top settings commonly
are site of comparatively increased intensity of the local ground
shaking. Therefore, care should be taken in constructing cohesive,
strong pads.
GEOLOGIC HAZARDS
Geologic hazards consist chiefly of the high ground shaking, possible
at this site and the possibility of inconsistent character of the
native-top formations mapped ar and near this site. Differential
settling and compaction could be a problem beneath foundation systems,
unless properly addresses.
CONCLUSION AND RECOMMENDATION
GENERAL
From a soil and foundation engineering standpoint, the site will be
suitable for the proposed single family residential construction,
provided the conclusions and recommendations presented in this report
are incorporated in the design cClnsiderations, project. plans and
specifications. '
Lakeshore Engineering
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August 25, 1997
Project No: 96-032.PI
Page Four
GRADING AND EARTHWORK
General
Based upon our site observation, it is our understanding that there
will be moderate amount of site grading. Site grading will be required
to provide: 1) nearly level building pad of adequate size; 2) suitable
foundation conditions to support the proposed building structure; 3)
adequate surface gradients for contrpl of water runoff; 4) excavation
into native soils and/or compacted fills to accommodate the
installation of foundation and utility systems and 5) the preparation
of competent subgrade for pr9posed driveway and concrete
sidewalk/flatwork.
After the areas to be graded have been stripped and cleared of
vegetation, the exposed soils will be'considered satisfactory for reuse
in the construction of on-site fills.
Prior to placing new fills, the botto~ removal/excavations should first
be inspected for competency, then scarified another 12 inches and
densified to at least 90 percent of the maximum laboratory dry density
as determined by the A.S.T.M. Dl157-7~ compaction method, should extend
at least 4 feet beyond the building footprints.
Any surface or subsurface obstructions encountered during grading such
as utility/irrigation lines should be removed from amy areas to receive
fills. No underground obstructions n9r facilities should remain in any
structural areas which will receive compacted fills, building
foundations, concrete slabs and/or p~vements.
Depressions and/or cavities created as a result of the grading
obstruction removal, should be prope~ly backfilled with suitable fill
materials and compacted under engineering observation and testing.
All imported soils should be approve~ by the consultant prior to use.
Caution should be exercised to prevent mixing of native or imported
materials with soils containing debris and/or organic matter. Any
objectionable substance, as determined by the consultant should be
stripped and removed from the property of stockpiled for landscaping
purposes. All fills should be dertSified in conformance with the
appropriate grading code but shall not be less than 90 percent relative
compaction, by mechanical means only.
For transitional cut/fill building pad, the cut portion of the pad
should be overexcavated at least 36 inches and the exposed bottom
scarified another 12 inches to mitigate potential differential
settlement.
Lakeshore Engineering
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August 25, 1997
Project No: 96-032.PI
Page Five
EXCAVATING CONDITION AND RIPPABILITY
Excavation of on-site materials should not be difficult to accomplished
with standard earthmoving equipment such as a D-4 or 5. The walls of
temporary construction trenches sh04ld stand near vertical, provided
the total depth does not exceed 5 fe~t. Shoring of excavation walls or
flattening of slopes is expected to Qe required, if greater depths are
necessary. For deeper cuts, slopes s~ould not be made steeper than 1:1
(H:V) .
All work associated with trench shoring must conform to the State of
California Safety Code. Native organtc free soils, may be utilized for
trench backfill. Flooding of the trench backfill may be permitted
provided both the backfill and the native materials have a minimum sand
equivalent of 30 and the required relative compaction can be achieved.
PROPOSED SLOPE STABILITY
CUT SLOPE - Based on review of the precise grading plan for this lot,
cut slopes are proposed at 2:1 (H:V) ratio and to a maximum
height of 14 feet.
The proposed design cut slopes are within UBC standard
guidelines and should be considered grossly stable
from deep seated failurr.
FILL SLOPE -Fill slopes are proposed at 2:1 (H:V) ratios and varies
from 5 to about 38 feet in height. 3/4 of the fill slope
will be limited to less than 30 feet in height with about
1/4 exceeding the 30 feet height. Fill slopes limited to 30
feet in height and inclined at 2:1 (H:V) slope ratio should
be considered stable. prqposed slopes are considered to be
grossly stable and should be suitable for its intended use
when constructed using s~lect fill material and under the
soil engineer's supervision and testing.
For fill slope section exceeding 30 feet in height, a
midslope 6 foot wide terrace bench is recommended. This
terrace bench should be lined with a concrete 2-foot wide
concrete swale to intercept the surface runoff flows.
Please see grading plan ~or location of interceptor swale.
Lakeshore Engineering
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August 25, 1997
Project No: 96-032.PI
Page Six
SLOPE KEYWAY AND BENCHING
Construction of fill slope will q~quire keyway and benching into
competent material before fill placement. Depth to competent soils is
estimated to be 4 to 5 feet below grade, therefore keyway dimension
should be at least 5 feet in depth and of 15 feet in width. Actual
keyway sizes are to be determined in the field during field excavation
inspections by the consulting geologist and/or engineer.
Benching into competent natural terr~in will be required to provide a
satisfactory bond between fill over native material. The benches are
cut vertical and limited to 4 feet or less in height. Field conditions
(exposed cuts) will dictate the location and allowable height of
benches. Inspection of benching dpring the grading operation is
required to verify that the contqct between fill and native is
satisfactory for its intended purposF'
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GRADING CONTROL
All grading and earthwork including trench backfill should be performed
under the observation and testing of the Consulting Engineer for proper
subgrade preparation, selection of satisfactory materials, placement
and compaction of structural fills. 'Sufficient notification prior to
stripping and earthwork construction is essential in order that the
work be adequately observed and tested. In order for us to provide a
written opinion as to the adequacy qf the soil compaction and trench
backfill, the entire operation, most importantly at the time of trench
backfill, should be performed under our observation and testing.
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FOUNDATION DESIGN
FOOTINGS
The proposed residential development may be supported on conventional
spread footings established in competent native soils or reworked
soils. These spread footings may be pesigned for an allowable bearing
value of 1500 pounds per square foot. This design value may be increase
by one third, if the Structural Engineer takes into consideration short
duration structural loading conditio~s, such as induced by wind and/or
seismic forces.
Footings should be founded at least 1~ inches below the lowest adjacent
ground surface, for two story structpres respectively. All continuous
foundations should be reinforced with at least one no. 4 rebar at top
and one at bottom and consistent with recommendations of the Structural
Engineer or Architect.
Lakeshore Engineering
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August 25, 1997
Project No: 96-032.PI
Page Seven
SETTLEMENT
Total settlement due to structural loads should not be a design factor
as they should be less than 0.5 inches. Differential settlement should
be within tolerable limits. I
LATERAL CAPACITY
For design, resistance to lateral loads can be assumed to be provided
by friction acting at the based of the foundations and by passive earth
pressure and may be combine wi th9ut reduction. If passive earth
pressure is used, it is important that backfill should be placed under
engineering observation and testing.!
A coefficient of friction of 0.35 may be used with the dead load
forces. An allowable lateral passive earth pressure of 200 pounds per
square foot per foot of depth may be used for the sides of footings
poured against undisturbed and/or recompacted soils.
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The lateral bearing values indicateq above are for the total of dead
and frequently applied live loads. I~ the normal code requirements are
used for seismic design, the values fay be increased by 1/3 for short
durations of the loading which include the effect of wind or seismic
forces. I
EXPANSIVE SOILS
Based upon our exploratory efforts and testing, the site is underlain
by granular sandy soils of low expansion potential. Clays are lacking.
CONCRETE SLAB-ON-GRADE
The subgrade soils are considered tp be non expansive. The interior
building floor slabs may be supported directly on properly prepared
subgrade. Presaturation of subgrade soil is not required. If a floor
covering that could be critically affected by moisture, such as vinyl
tile, slabs should be protected by a plastic vapor barrier of six-mil
thickness. The sheet should be cover~d by at least two inches of sand
cushion to prevent punctures and aid in concrete cure.
The concrete floor slabs should be at least 4 inches thick actual and
reinforced with at least 6"x 6"/10-10 welded wire mesh or equivalent
reinforcing. Concrete driveway, sid~walk, gazebo, fire pit and patio
slabs should also be reinforced as suggested above and the bottom
cushioned with 2 inches of rock base or granular sand.
Lakeshore Engineering
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August 25, 1997
Project No: 96-032.PI
Page Eight
RETAINING WALLS - No walls are proposed at this time.
DRAINAGE
Positive drainage should be provid,ed around the perimeter of all
structures to minimize water infiltrating into the underlying soils.
Finish subgrade adjacent to exterior footings should be sloped down and
away to facilitate surface drainage. All drainage should be directed
off-site to the street via non-erosive devices.
The homeowner should be made aware of the potential problems which may
develop when drainage is altered tprough construction of retaining
walls, patios and pools. Ponded water, leaking irrigation systems,
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overwatering or other conditions which could lead to ground saturation
must be avoided.
FOOTING EXCAVATION
All footing excavations should be in~pected and approved by the Soils
Consultant prior to placement of forms, reinforcement, or concrete.
Materials generated from the footing excavations should not be spread
on slab-on-grade areas, provided they are compacted and tested.
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GENERAL INFORMATION
The findings and recommendations of this report were prepared in
accordance with generally accepted professional engineering principles
and practices in the fields of soil mechanics and foundation
engineering. This warranty is in lieu of all other warranties, either
expressed or implied.
We sincerely appreciate the opportuqity to be of service.If you have
any questions concerning this report or require further information and
services, please ~~~~act ,his office' at your convenience.
"...J.,.....s.'{i.
Respectfully ~~D~~~t~~'~
LArSHORE ENGIJl' ERING ,q ~~\.
~ #37442 t;
FEN YONG, R.C..E.~ ,,~42)
Exp. f-30-00 "\. "" ,...
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FY/fy
ENCLOSURES: GRADING PLAN IN POCKET
APPENDIX A - EXPLORATION
APPENDIX B - LABORATORY TESTING
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Lakeshore Engineering
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APPENDtX ~
FIELD EXPLPRATION
Field exploration was performed by using a (Jack Curtis) backhoe, on
the moring of June 10, 1996. The soils were continuously logged by our
field personnel and classified by vispal examination in accordance with
the Unified Classification System. Our trench logs and/or boring logs
are attached for review.
To evaluate the compaction charactertstics of the fill material, field
density tests were performed. Also, ,representative bulk samples were
recovered and shipped to the labqratory in pOlythelene bags for
laboratory testing. I
Glenn & Pat Crowther
96-032.PI
Lot 8, Piasano Place
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Lakeshore Engineering
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TRENCH LOG
Logged By: F .~~ .. Trench
Date b- IO-.jC, Number
Equipment: (JAll:to";;, ~'" . T l
ThilloQ Is I representalionol subsurtace, soil IndgrounctNlIerconditlOllI II lhe tlmea nd place 01 excavation, - ,
w1lhlhep.ssaQllollimeoralanyotht!r Iocallon there may be cof'lllequential changes in condKions.
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l:&/U CD,)N - [)EA:l~e., "I'd ~cJ\L P I'lu.IS A
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TOTAL l) CPTt-l f. ~/4 \
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NOIUI.t ~\t)E.( hbEof' C:xl::'\\fo,lG, ,PAD,
Surface Elevation:
Trench Orientation: ~-\.C)
Trench Dimensions: 1.t;.'" >CI f)<: tt',-
Groundwater Depth: ONE..
Logged By: SflliVIlZ.. M ItMJE:..
Date
Equipment: $,(.. of PA-C.
FILL- ~N,LT.~~ L.trO","E..5' DP-\/ ~l.l\,
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LAKESHORE
Engineering
CONSULTING ENGINEERS AND GEOLOGIST
Trench
Number
T-L
Fig, No.
PROPOSED RESIDENCE
GLENN & PAT CROWTHER
PIASANO PLACE
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PROJ. NO.
'1(;" 032 ,t':L.
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APPENDIX B
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LABORATORY TESTING
MOISTURE DENSITY RELATIONSHIP
Moisture - density information usually provides a gross indication of
the soil consistency and can delineate local variations at the time of
investigation and provide a correlation between soils found on this
site. The dry unite weight and field moisture content were determined
for selected samples, and the results are shown on the log of boring
sheets.
MAXIMUM DENSITY - OPTIMUM MOISTURE TESTS
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A selected soil sample was tested in the laboratory to determine
maximum dry density and optimum moisture content using the A.S.T.M.
D1557~78 compaction test method. This test procedure uses a 10 pound
hammer falling a height of 18 inches on each of five layers to a 1/30
cubic foot cylinder. The results of the tests are presented below:
Trench Depth Soil Maximum Dry Optimum Moisture
No. (Ft. ) Description Den1lity (P.C.F) Content (% Dry Wt. )
------ ----- ----------- --------------- -------------------
T-1 3 Sil ty SAND 123.0 11. 8
EXPANSION INDEX TEST
A representative soil sample was collected in the field and tested in
the laboratory in accordance with the A.SC.E. Expansion Index Test
Method as specified by U.B.C. The degree of expansion potential was
evaluated from measured soil volume changes obtained during soil
moisture alterations. The results of'the test are presented below:
Trench Depth Soil Expansion Expansion
No. (Ft. ) Description Inp.ex Potential
------ ----- ----------- ----------- ----------
T-1 3 Sil ty SAND 23 LOW
Glenn & Pat Crowther
96-032.PI
Lot 8, Piasano Place
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Lakeshore Engineering