04-3856 (CSCS) Preliminary Geotechnical Investigation0
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PRELIMINARY GEOTECHNICAL INVESTIGATION,
PROPOSED
WASHINGTON SQUARE COMMERCIAL CENTER,
LOCATED AT
THE SOUTHEAST CORNER OF
WASHINGTON
STREET AT HIGHWAY 111,
LA QUINTA, CALIFORNIA
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° LEIGHT®N AND ASSOCIATES, INC.
1961 Geotechnical and Environmental Engineering Consultants
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PRELIMINARY GEOTECHNICAL INVESTIGATION,
PROPOSED WASHINGTON SQUARE COMMERCIAL CENTER,
LOCATED AT THE SOUTHEAST CORNER OF
WASHINGTON STREET AT HIGHWAY 111,
LA QUINTA, CALIFORNIA
February 4, 1991
Project No. 6901579-01
Prepared For:
BIRTCHER
72-010 Varner- Road
Thousand Palms, California 92276
1737 ATLANTA AVENUE" SUITE 1, RIVERSIDE" CALIFORNIA 92507
(714)788-5800
FAX ( 714) 788-0831
6901579-01
SCOPE OF WORK
The scope of our work for this investigation included:
• Review of available geotechnical data.
• Site reconnaissance by Senior Staff Geologist.
• Excavation of 7 exploratory Iborings up to 30 feet in depth.
• Laboratory testing of representative soil samples.
• Analysis of field and laboratory test data.
• Preparation of this report presenting our findings, conclusions and
recommendations.
We have used a map titled "Conceptual Grading Plan," dated January 15, 1991,
prepared by Engineering Service Corporation (ESCO), as a base for our
Geotechnical Map (Plate 1 - In Pocket). This map shows the conceptual layout of
the.proposed building pads and the tentatively proposed pad grades. No existing
topography is shown on this map. We have also reviewed a set of 40 -scale
topographic maps of the site, and also prepared by ESCO, dated June 11, 1990.
Accompanyinq Maps and ADoendices
• Figure 1 - Site Location Map - Page 2 t
Plate -1 - Geotechnical Map - In Pocket
Plate 2 - Spread Footing Design Chart, Rear of Text
Appendix A - References
Appendix B - Geotechnical Boring Logs
Appendix C - Laboratory Test Results
Appendix D - General Earthwork and Grading Specifications
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SITE LOCATION MAP
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SITE LOCATION MAP
Base Map: USGS 7y' Series La Quinta Quadrangle, 1959 (Photorevised 1980).
Proposed Washington Square Commercial
• Development, East.of Washington Street and
South of Highway 111, La Quinta, California
Project No. 6901579-01 FIJ?
I
IpilDate FPhruary 4- 1991 1C
1040 239
Page 2 Figure No.
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Base Map: USGS 7y' Series La Quinta Quadrangle, 1959 (Photorevised 1980).
Proposed Washington Square Commercial
• Development, East.of Washington Street and
South of Highway 111, La Quinta, California
Project No. 6901579-01 FIJ?
I
IpilDate FPhruary 4- 1991 1C
1040 239
Page 2 Figure No.
4
• Earth Materials
SUMMARY OF GEOTECHNICAL CONDITIONS
6901579-01
The earth materials encountered in our investigation consist predominantly of
windblown deposits composed of gray, fine grained sands and silty sands with
occasional layers of alluvial silt and fine sandy silt. Layers of these silty
soils form when runoff water carrying suspended fine grained soil particles
collects in low-lying areas, allowing these fine soil's to settle out. Because
the sand dunes migrate over time, these silt layers are eventually buried beneath
the dunes.
The sandy soils are generally loose and dry near the ground surface, and become
medium dense at depths below approximately 10 feet. Laboratory testing of 3
samples of the sandy soils indicated 9 to 26 percent passing the No. 200 sieve,
with sand equivalent values ranging from 34 to 63. Based on their classification
(SM, SP -SM and SP) and granular nature, these soils are expected to have a low
potential for expansion when wetted.
As discussed previously, the silty soils (ML) are present in the form of layers
within the windblown sand. Laboratory testing of these soils indicated 70
percent passing the No. 200 sieve, with a low sand equivalent value of 4. An
Atterburg limits test was performed on a representative sample of the silt, and
it was found to be non -plastic. Field classification also indicates that these
soils are non -plastic (NP). Based on this, these soils are also expected to have
a low potential for expansion when wetted. Because these soils are dry and only
• soft to medium stiff, they may have some potential for collapse when wetted.
The silty soils appear to be most prevalent in the southwest corner of the site.
Because of the limited scope of this preliminary investigation, we cannot
precisely determine the extent to which these soils will affect building
foundations in this area. Additional building -specific investigations should be
performed for structures proposed in the southwest corner of the site in order
to delineate the vertical and lateral extent of these silt layers, and to
determine their potential for collapse. The collapse potential (if any) of these
soils can be readily mitigated by processing and densification of the near
surface soils during grading, in accordance with the recommendations in this
report, and future, more detailed, geotechnical reports.
Groundwater
No free ground water was encountered in any of our borings at the site. The
Coachella Valley Water District (CVWO) has a well located near the intersection
of 47th Avenue and Adams Street, adjacent to the southeast corner,of the site.
CVWD indicates that the average annual depth to groundwater in that well during
1989 was 117.5 feet below the ground surface. The average annual depth to ground
water in another CVWO well located just to the northwest of the site was 112.4
feet below the ground surface. This level may fluctuate seasonally, however,
ground water is not expected to impact construction at the site.
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6901579-01
Faulting/Seismicity
• Pio active faulting is suspected to be present at or immediately adjacent to the
site based on our investigation and data review. The hazard from ground rupture
due to fault movement within the site is therefore considered to be negligible.
The nearest active or potentially active fault to the site is the San Andreas
fault, located approximately 5- 1/2 miles northeast of the site. Northwest of the
site, this fault becomes two major northwest -southeast trending branches: the
Banning Fault and the Mission Creek Fault. The active San Jacinto Fault is
located within the mountains, about 17 miles to the southwest.
We have performed a computerized deterministic seismic analysis which evaluates
the peak horizontal ground acceleration, the duration of shaking and the
predominant period of shaking that would be expected to occur at the site as a
result of a Maximum Credible Earthquake (MCE) occurring on any of the significant
known faults within a 100 kilometer, (62 miles) radius of the site. The MCE is
the largest earthquake that a fault appears to be capable of producing,
regardless of time, given the current understanding of the regional tectonic
framework. Because we assume that the MCE will occur at the point on each fault
that is nearest the site, it is inherently a conservative analysis. Our analysis
indicates that the San Andreas System would be expected to be the source of the
strongest ground motions at the site. If the MCE, considered to be a magnitude
8.0 event (Working Group, 1988; Idriss, 1987), were to occur nearby on the San
Andreas Fault, a maximum peak horizontal ground acceleration of 0.47g could be
expected to occur at the site (Campbell, 1988). Such an event would produce 50
seconds -of groundshaking (based on interpretation of Dobry, 1978; and Trifunac,
1915), with a predominant period of 0.40 seconds (Seed, 1969).
• Because of the significant depth to groundwater, liquefaction is not considered
to pose a hazard to development at the site.
Wind Erosion
The presence of the sand dunes at the site indicates that erosion, transportation
and redeposition of sand by the wind is an ongoing process at the site. The
United States Department of Agriculture, Soil Conservation Service (USDA -SCS,
1967) has mapped wind erosion status and hazards within the Coachella Valley.
The USDA -SCS mapping indicates that the wind erosion hazard in the site area is
classified as .Slight to Moderate. Blowing dust and sand can be expected when
soils are disturbed during grading operations.
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6901519-01
CONCLUSIONS
•
Thi _s preliminary geotechnical investigation indicates that the subject site is
9 J
generally suitable for the proposed development, from a geotechnical standpoint,
if the recommendations provided in this report are implemented in the project
design and construction. Based on a review of more detailed grading plans and
structural load information, when available, additional investigation may be
necessary in order to provide final site preparation and foundation design
recommendations. However, there are no known geotechnical constraints affecting
the site which cannot be mitigated by proper planning, design and sound
construction practice:
Additional conclusions are summarized as follows:
• The onsite earth materials are suitable for use as compacted fill and can be
readily excavated using conventional heavy duty earthmoving equipment in good
working condition.
The near surface soils are loose and dry, and therefore will require some
overexcavation, moisture conditioning (by thorough watering/flooding) and
recompaction in order to provide adequate bearing capacity and minimize
potential settlements.
• Based on their classification and non -plastic nature, the .onsite soils are
expected to have a very low potential for expansion.
• No known faults are present at the site and therefore, ground rupture hazard
is very low. However, significant ground shaking resulting from nearby
earthquakes should be anticipated during the life of the proposed
development.
•
• Ground water is on the order of 100 feet or more below the ground surface and
therefore should not impact construction at the site. Liquefaction is not
considered to pose a hazard for development of this site.
• Onsite soils are prone to wind and water erosion. Blowing sand would be a
consideration during and after grading.
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6901579-01
RECOMMENDATIONS
1. Grading/Foundation Plan Reviews
A plan review should be performed by this office when grading and
foundation plans, and more detailed structural load information become.
available. Additional site specific investigation(s) may be warranted
based on this review.
2. Site Preparation
Proposed building and pavement areas should be cleared of all vegetation,
trash and debris which should be disposed of offsite. After clearing,
structural areas should be over -excavated to an elevation at least three
feet below existing ground or proposed pad grade, whichever is deeper.
This excavation should extend at least five feet outside the proposed
exterior footing lines, or 1:1 (horizontal to vertical) projection form
the edge of exterior footings. The exposed excavation bottom should be
scarified, thoroughly watered to saturate the soils and recompacted to at
least 90 percent relative compaction. The soils engineer should observe
and approve all over -excavation bottoms prior to replacement of compacted
fill to achieve design grades. All areas to receive fill should be
scarified, thoroughly watered and compacted to 90 percent relative
compaction prior to fill placement.
In addition to the above,. all footings should rest on at least 2 feet of
controlled compacted fill..
3. Compacted Fill
Onsite soils, excluding any deleterious materials, are anticipated to be
suitable for use in compacted fills. Any imported soil to be placed as
fill should be approved by the soil engineer. All fills should be placed
in 6- to 8 -inch .(loose) lifts and compacted to at least 90 percent
relative compaction relative to the maximum dry density as determined by
the Standard Test Method ASTM D1557-78.
4. Shrinkage Factor/Subsidence
Removal and re.compaction of the near surface soils should result in a
shrinkage of approximately 20 percent (±5 percent). This is based on an
average 92 percent relative compaction. An increase in relative
compaction obtained would cor sp ingly increase this shrinkage factor.
Furthermore, a subsidence of 0.25 foot should be considered during site
preparation. These value exclusive of losses resulting from
stripping and removal of any un erground obstructions.
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6901579-01
Tentative Foundation Design
For planning purposes, the use of shallow continuous footings or isolated
spread footings should be feasible after site preparation as recommended.
Footings should be a minimum of 12 inches wide and embedded at least 12
inches below lowest adjacent firm grade. The allowable bearing pressure
corresponding to width and embedment may be obtained from Plate 2, Spread
Footing Design Chart. The maximum allowable bearing pressure is 2,500
psf. This value may be increased by one-third for transient loads such as
those imposed by wind or seismic forces. Footings should be reinforced
with at least one No. 4 bar at the top and bottom to reduce the potential
for cracking due to temperature and shrinkage stresses and a limited
amount of hydroconsolidation. Foundation design, parameters for heavier
structures should be based on specific structural load information and
site specific geotechnical investigation.
.It is important to minimize the infiltration of water into the foundation
soils after construction to reduce the potential for adverse amounts of
settlement. Positive drainage should be provided to direct surface water
away from structures and slabs towards the streets or approved drainage
devices.
6. Slabs -On -Gra
Typical floor slabs should be at least 4 inches thick and should be
reinforced in accordance with local codes and structural considerations.
We suggest that slabs -on -grade be reinforced by either wire mesh (6 x 6 -
10/10 WWF) or No. 3 rebars at midheight in the slabs, spaced 24 inches on
center in both directions. We recommend that a moisture barrier
consisting of a 6 -mil polyethylene sheet be placed beneath slabs in areas
sensitive to moisture damage. Openings in the vapor barrier (for utility
connections etc.) should be carefully sealed, and the vapor barrier
carefully installed to avoid puncturing it and reducing its effectiveness.
Any slabs which will be subjected to heavy loads should be designed based
on structural considerations.
7. Lateral Earth Pressures/Walls Below Grade
The following lateral earth pressures and soil parameters may be used for
design of retaining walls with free draining, level backfills. Resistance
to lateral loads can be developed by frictional resistance on the footing
bottoms and passive pressure against footing sides. The top one foot of
embedment should be neglected when computing passive pressure unless the
area adjacent to the foundations is confined by a slab or pavement.
Active Earth Pressure (Pa): 35 pcf (EFP), drained, yielding
condition
• At Rest Pressure (P.): 55 pcf (EFP), drained, unyielding
condition
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6901579-01
• Passive Earth Pressure (Pp): 300 pcf (EFP), with a maximum value
of 2,500 psf
• Lateral Earth Pressure Due
to Areal Surcharge (P q):
• Horizontal Coefficient of
Friction (µ):
• Unit Soil Weight (y,):
0.30 x Surcharge Weight
(Rectangular Distribution)
0.30
110 pcf
Note: If passive earth pressure and friction are combined to provide
required resistance to lateral forces, thee value of the passive
pressure should be reduced to two-thirds of the above
recommendations.
8. Cut and Fill Slopes
Cut and fill slopes should be graded at inclinations of 2:1 (horizontal to
vertical) or flatter. All fill slopes should be 'overbuilt and trimmed
back to expose compacted slope surfaces.
9. Cement Type/Corrosion Potential
Although no sulphate tests have been performed, we suggest the use of
Type II cement for concrete in contact with earth materials. The use of
low slump concrete, not exceeding 4 inches at the time of placement, is
• recommended. Metal pipes may be protected by bituminous coating or
galvanizing, etc. If considered critical, corrosion potential should be
evaluated by a corrosion engineer.
10. Drainage
To minimize the potential for hydroconsolidation, special attention should
be given to avoid the saturation of foundation soils. Adequate positive
drainage should be provided to direct surface water away from the
foundations and into approved drainage devices. Planters with open
bottoms should be avoided in areas adjacent to foundations. Drainage
devices should also be designed to prevent the flow of water over graded
slopes.
11. Trench Excavations and Backfills
Trenches greater than 5 feet in depth should be shored or sloped at 1:1
(horizontal to vertical) in accordance with California OSHA requirements.
Backfills in the utility trenches should be compacted to at least 90
percent. relative compaction. The onsite soils, if free of deleterious
materials, are expected to be suitable for use as backfill material.
Sandy materials with a sand equivalent value of at least 30 should be
utilized for the pipe zone.
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6901579-01
12. Tentative Pavement Qg.i_
• On the basis of laboratory classifications of onsite soils, we are of the
opinion that the tentative pavement design may be based on an estimated R -
value of about 40, corresponding to the near surface soils. For planning
purposes, a tentative pavement section consisting of at least 3 inches AC
over 4 inches aggregate base is recommended for parking and driveway
areas. Pavement areas which will be subjected to truck traffic should be
tentatively designed using 3 inches AC over 6 inches aggregate base.
PCC paving at entrance and driveways may consist of 7 inches and 7.5
inches (over native subgrade compacted to at least 95 percent in the upper
12 inches) for 4,000 psi and 3,000 psi concrete compressive strength,
respectively.
Final pavement design recommendations should be based on R -value tests of
representative pavement subgrade soils upon the completion of rough
grading. 1.
13. Seismic Considerations
Seismic design considerations for structures in the Southern California
area are critical because of high regional seismic activity. As a minimum,
seismic design for the proposed structures should be in accordance with
the most current edition of the Uniform Building Code, and the seismic
design parameters of the Structural Engineers Association of California,
and should consider the seismicity information presented in this report.
• 14. Wind Erosion
Special consideration should be given to the blowing dust and sand which
will probably occur during grading operations at the proposed site.
Adequate pre -watering of exposed soils prior to grading and watering
during grading, combined with limiting the area of dry, exposed soils can
be expected to mitigate this condition during earthwork construction.
After site development, a level of mitigation against wind erosion could
be provided by maintaining moist surface soils, planting stabilizing
vegetation, and establishing of wind breaks, such as rows of tamarisk
trees, and/or perimeter block walls. These procedures have been used
successfully elsewhere in the valley.
15. Observation and Testing During Construction
The recommendations provided in this report are based on preliminary
design information and subsurface conditions obtained from the exploratory
borings at the site. Leighton and Associates should review the final
project drawings to verify that the recommendations provided in this
• Vy��t'S
10 - I�1961
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6901579-01
report are incorporated in the project plan. Construction should be
observed by Leighton and Associates at the following stages:
• Upon completion of clearing and during excavation of building and
• pavement areas.
•� During all stages of grading and earthwork operations including
overexcavation, scarification, recompaction, and utility trench
backfilling.
•
• Prior to paving or other construction over fill or backfill.
When any unusual soil conditions are encountered during construction
A final report should' be prepared upon completion of the construction
summarizing the compliance- with the recommendations of this report and
geotechnical observations made during the grading work. If conditions
during construction appear to be different from those indicated in this
report, this office should be notified.
16. Materials Testing/Deputy Inspections
Materials testing for concrete, steel, masonry, grout, etc., and deputy
inspections should also be performed by Leighton and Associates, Inc.,
during construction.
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Soil ParameL°rs
= 32.5
c = 0 psf
Yt = 110 psf
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SPREAD FOOTINGS DESIGN CHART
I
NOTE
• Or = Oepth of Footing
F.S. = Factor of Safety
Project No. 6901579-01
2 3 4 5
B,WIDTH OF SPREAD FOOTING (FEET)
Note : Maximum Aflowable Beariig
Pressure - 2,500 psf
Minimum Fooling Width = 1.0 foot
Hinimum Footing Depth
Below Lowest Adjacent Grade = 1.0
Plole: 2
3'
pf
Df
I
NOTE
• Or = Oepth of Footing
F.S. = Factor of Safety
Project No. 6901579-01
2 3 4 5
B,WIDTH OF SPREAD FOOTING (FEET)
Note : Maximum Aflowable Beariig
Pressure - 2,500 psf
Minimum Fooling Width = 1.0 foot
Hinimum Footing Depth
Below Lowest Adjacent Grade = 1.0
Plole: 2
•
6901579-01
APPENDIX A
References
Campbell, K. W., 1988, Preliminary Report on Empirical Studies of Horizontal
Strong Ground Motion for the Diablo Canyon Site, California, Prepared for
the U.S. Geological Survey, Reported to the U.S. Nuclear Regulatory
Commission, dated October 1988.
Coachella Valley Water District, 1991, Personal Communication with Mr. Brad
Gummer, January, 29, 1991.
Dobry, R., Idriss, I. M.., and Ng, E., 1978, Duration Characteristics of
Horizontal Components of Strong Motion Earthquake Records, Bulletin of the
Seismological Society of America, 68 (5) 1487- 1520'.
Idriss, I.M., 1987, Earthquake ground Motions, Lecture Notes, Course of Strong
Ground Motion, Earthquake Engineering Research Institute, Pasadena,
California, April 10 -11, 1987.
Riverside County Comprehensive General Plan, March 6, 1984, by the Board of.
Supervisors of Riverside County Resolution 84-77, with revisions through
December 22, 1987.
.i
Seed, H. B., Idriss, I. M., and Kiefer,. F. W., 1969, Characteristics of Rock
Motions During Earthquakes, Journal of Soil Mechanics and Foundation
Division, ASCE 95, Vol. 95, -No. SMS, Paper 6783, pp. 1199-1218.
Trifunac, M. D., and Brady, A. G., 1975, A Study On The Duration of Strong
Earthquake Ground Motion, Seismology Society of America Bulletin, Vol. 65,
pp.581-645.
The Working Group on California Earthquake Probabilities, 1988, Probabilities of
Large Earthquakes Occurring in California on the San Andreas Fault, U.S.
Geological Survey Open -File Report 88-398, pp 62.
A-1
A-0
•
•
a
•
MAJOR DIVISIONS
RANGE OF GRAIN SIZES
TYPICAL NkM ES
SYMBOLS
FICATION
GRAVELS
GW
O'
�p, 0'
Well grades gravels or gravel sand etxtures. e or no fine
N.IllImeters
BOULDERS
ABOVE 12
op
Q Q
0
Poorly graded ; rave l• or gravel sand s.:xtura,. !ltt!e or
305 to 76.2
N
{M^re than 1/2 of
76.2 to 4.76
COARSt
.
no fine*
PINI
_J
coarsa frac Clon >
SAND
No. 4 to 200
4.76 to 0.074
COARSE
140. 4 to 10
4.76 to 2.00
R
no. 4 .:eve s1:e)
GH
FINI
No. 40 to 200
I
0.420 to 0.014
Silty gravels• ^, rave 1 Rend silt ,�:ztu;es
BELOW No. 200
p o
b
i
Z
1'-o
GC
Clayey gravels. ;ravel -Sand -clay ■ixtures
L 01
SANDS
Sw
•• , •' :
Well -graded Rands or gravelly sands. little or
y� •
no f: -,es
L
(Nor• than ./2 of
SP
a 44 • s
Poorly graded sands or gravelly sande, little or no !imam
coarse fraction t
'{.
no. 4 sieve alae)
s H
,I.
Silty sands, sand -tilt mixture's
SC
Clayey sands, sand -clay mixtures
ML
Inorganic silts and very fine sands, rock flour. silt/ or
SILTS L CLAYS
clayey fine sands or clayey silts with all plasticity
jCL
Inorganic clays of low to medium plasticity, gravelly c1alr,
..
LL < 50
sandy clays. Silty clays, lean clays
)E;
\C
Ti
L
Organic silts and organic silty clays of lov plasticity
z
< c C3
ty * C)
U N
1�
Inorganic silts, micaceous or diatceeaceous fine Bendy or tLlty
`•'
SILTS L CLAYS
Dolls, elastic silts
zs
Z l
v
LL > 50
CEI
Inorganic clays of high plaaticity, fat clays
Cfg
Organic clays of tedium to high plasticity, organle silty
clays, organic etlta
HIGHLY ORGANIC SOILS
P t
Peat and other highly organic soils
CLASSIFICATION CHART
(UNIFIED SOIL CLASSIFIChTION SYSTEM)
GRAIN SIZE CHART
D
RANGE OF GRAIN SIZES
CLASSI-
FICATION
U.S. Standard
Grain Size in
Steve Size
N.IllImeters
BOULDERS
ABOVE 12
ABOVE 305
COBBLES
12' to 3'
305 to 76.2
GRAVEL
3• to No. l
76.2 to 4.76
COARSt
3' to 3/4'
76.2 to 19.1
PINI
3/4- to No. 4
19.1 to 4.76
SAND
No. 4 to 200
4.76 to 0.074
COARSE
140. 4 to 10
4.76 to 2.00
hEDIVX
No. 10 to 40
2.00 to 0.420
FINI
No. 40 to 200
I
0.420 to 0.014
SILT& CLAY
BELOW No. 200
EELCtir 0.074
GRAIN SIZE CHART
D
10
4
0
0 1: :0 ]0 40 10 60 %0 30 90 :)0
LIQUID LIMIT
METHOD OF SOIL CLASSIFICATION
PLASTICITY CHART
69015_79-01
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389
CH
4
CL
CH
t
i
HL LOt
10
4
0
0 1: :0 ]0 40 10 60 %0 30 90 :)0
LIQUID LIMIT
METHOD OF SOIL CLASSIFICATION
PLASTICITY CHART
69015_79-01
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' =• Flqur e ,;o.
:OBO 01-
389
6901579-01
KEY FOR GEOTECHNICAL LOGS
•
SAMPLING/TESTING
® - RING SAMPLE
® - BAG SAMPLE
* - MUNSEL SOIL COLOR NOTATION
® - STANDARD PENETRATION TEST
(90) -
RELATIVE COMPACTION
GS -
GRAIN SIZE ANALYSIS
SE -
SAND EQUIVALENT
•
CP -
MAXIMUM DENSITY/OPTIMUM MOISTURE
CN -
CONSOLIDATION
DS -
DIRECT SHEAR
RS -.
REMOLDED SHEAR
EI
- EXPANSION INDEX
AL
- ATTERBERG LIMITS
NR
- NO RECOVERY
®
- GROUND WATER
0
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GEOTECHNICAL BORING LOG
Date:_ 1/21/91 Drill Hole No. _.8-1 Sheet 1 of 1
Project Name Birtcher/Washington Square Project No. 6901579-01
Drilling Co. Datum Type of Rig CME 75/All Terrain
• :ole Diameter 8" Drive Weight 140 lbs. Drop 30" Elevation --
•
Type
Tube
Blows
Dry
Mois.
Soil
GEOTECHNICAL DESCRIPTION
Depth/
Earth
of
Samp.
per
Dens.
Cont.
Class
Logged by DG
Feet
Material
Test
Test
6 -inch
pcf
%
USCS
Sampled by DG
WIND
SP/SM
SAND/SILTY SAND: Gray, fine grained,
BLOWN
dry, loose, micaceous.
SANDS
(Qwbs)
2
3
3
GS
4
87
7
SM
With interlayers of thinly laminated
SE =
34
4
brown silt and brown, fine to coarse
grained silty sand.
Percent Passing No. 200 Sieve = 18.
1
5
6
1
Medium dense, no silt layers.
1
12
101
3
21
2
ALLUVIUM
1
11
ML
SILT: Light gray, dry, stiff, thinly;
(Qal)
11
laminated with light gray, fine silty
sand layers.
i
r
t
WINDSP/SM
SAND/SILTY SAND: Gray, fine grained.`
BLOWS
Idry, loose, micaceous.
SANDS
;
7
NR
I
TOTAL DEPTH AT 25' EASY DRILLING ;I
(Qwbs)
14
i
in rnniu.in i1nrcn orNnrur nnrvrri rnl i
C,
•
•
GEOTECHNICAL BORING LOG
Date 1/21/91 Drill Hole No. B-2 Sheet 1 of 2
Project Name Birtcher/Washington Square Project No. 6901579-01
Drilling Co. Datum Type of Rig CME 75/All Terrain
Hole Diameter 8" Drive Weight 140 lbs. Drop 30" Elevation --
Type
Tube
Blows
Dry
Mois.
Soil
GEOTECHNICAL DESCRIPTION
Depth/
Earth
of
Samp.
per
Dens.
Cont.
Class
Logged by DG
Feet
Material
Test
Test
6 -inch
pcf
%
USCS
Sampled by DG
WIND
SP/SM
SAND/SILTY SAND: Light brown, fine
BLOWN
grained, damp, loose.
SANDS
CP
(Qwbs)
3
NR
1
3
3
4
1
5
C
ALLUVIUM
8
85
10
ML
SANDY SILT: Gray, very fine
(Qal)
12
grained, dry, medium stiff with
interlayered thinly laminated brown
silt.
15--
WINO
SILTY SAND: Light gray, fine
BLOWN
SM
SANDS
grained (-30% silt), dry, medium r
(Qwbs)
dense with occasional thin layers of I
thinly laminated brown silt.
9
11
12
2
SP/SM
SAND/SILTY SAND: Gray, fine grained,
dry, loose, ,
8
14
25—
•
0
GEOILCHNICAL BORING LOG
Date 1/21/91 Drill Hole No. _B-2 Sheet 2 of 2
Pr6ject Name Birtcher/Washington Square Project No. 6901579-01
Drilling Co. Datum Type of Rig CME 75/All Terrain
:tole Diameter 8" Drive Weight 140 lbs. Drop 30" Elevation --
Depth/
Earth
Type
of
Tube
Samp.
Blows
per
Dry
Dens.
Mois.
Cont.
Soil
Class
GEOTECHNICAL DESCRIPTION
Logged by DG
Feet
Material
Test
Test
6 -inch
pcf
%
USCS
Sampled by OG
2
WIND
BLOWN
SP/SM
SAND/SILTY SAND: (Continued).
SANDS
(Qwbs)
SP
SAND: Light gray, fine grained, dry,
dense.
12
14
16
3
I
I
TOTAL DEPTH AT 30'
NO GROUND WATER
EASY DRILLING
BORING BACKFILLED
i
•
0
•
J )
GEOTECHNICAL BORING LOG
0at. e 1/21/91 Drill Hole No. B-3 _ Sheet 1 of 1
Project Name Birtcher/Washington Square Project No. 6901579-01
Drilling Co. Datum Type of Rig CME 75/All Terrain
dole.Diameter 8" Drive Weight 140 lbs. Drop 30" Elevation --
•
0
•
GEOTECHNICAL BORING LOG
Date 1/21/91 Drill Hole No. B-4 Sheet 1 of 2
Project Name Birtcher/Washington Square Project No. 6901579-01
Drilling Co. Datum Type of Rig CME 7S/All Terrain
riole Diameter 8" Drive Weight 140 lbs. Drop 30" Elevation --
.
Type
Tube
Blows
Dry
Mois.
Soil
GEOTECHNICAL DESCRIPTION
Depth/
Earth
of
Samp.
per
Dens.
Cont.
Class
Logged by DG
Feet
Material
Test
Test
6 -inch
pcf
%
USCS
Sampled by OG
WIND
SP/SM
SAND/SILTY SAND: Light brown, fine
BLOWN
grained, dry, medium dense.
SANDS
(Qwbs)
7--104--.
4
10
SM
SILTY SAND: Light brown, fine
grained, dry, medium dense.
SP/SM
SAND/SILTY SAND: Gray, fine grained,
dry, medium dense.
i
I
I
6
C
1
•
6
t
I
ALLUVIUM
SP/SM
SAND/SILTY SAND: Light olive -gray,
(Qal)
8
112
2
fine to medium grained with
14
occasional coarse grained sand,
1'
slightly damp, medium dense.
ML
SANDY SILT: Light gray, very fine to
9
fine grained sand factor, dry,
11
medium stiff.
12
201
WIND
SM
SILTY SAND: Light gray, fine
BLOWN
grained, dry, medium dense.
SANDS
(Qwbs)
7
11
--
--
i
2
•
<i
GEOTECHNICAL BORING LOG
Date 1/21/91 Drill Hole No. B-4 Sheet 2 of 2
Project Name Birtcher/Washington Square Project No. 6901579-01
Drilling Co. Datum Type of Rig CME 75/All Terrain
tole Diameter 8" Drive Weight 140 lbs. Drop 30" Elevation --
Depth/
Feet
2
Earth
Material
Type
of
Test
Tube
Samp.
Test
Blows
per
6 -inch
Dry
Dens.
pcf
Mois.
Cont.
%
Soil
Class
USCS
GEOTECHNICAL DESCRIPTION
Logged by DG
Sampled by DG
WIND
SP
SAND: Gray, fine grained, dry,
BLOWN
dense.
SANDS
(Qwbs)
14
20
30
3
TOTAL DEPTH AT 30'
NO GROUND WATER
EASY DRILLING
BORING BACKFILLED
.I
GEOTECHNICAL BORING LOG
Date 1/21/91 - Drill Hole No. B-5 Sheet 1 of l
Project Name Birtcher/Washington Souare Project No. 6901519-01
Orilling Co.- Datum Type of Rig CME 75/All Terrain
• .pole Diameter 8" Drive Weight 140 lbs. Drop 30" Elevation --
•
•
Type
Tube
Blows
Dry
Mois.
Soil
GEOTECHNICAL DESCRIPTION
Depth/
Earth
of
Samp.
per
Dens.
Cont.
Class
Logged by DG
Feet
Material
Test
Test
6 -inch
pcf
%
USCS
Sampled by DG
ALLUVIUM
ML
SANDY SILT: Light brown, very fine
(Qal)
to fine grained,.dry, medium stiff,
thinly laminated with interlayered
GS
7
88
3
silty sand.
SE =4
9
Percent Passing No. 200 Sieve = 70.
AL
6
Nonplastic.
7
WIND
SP/SM
SAND/SILTY SAND: Light gray, fine
j 1
BLOWN
11
92
1
grained, dry, medium dense.
SANDS
18
(Qwbs)
I
i
ALLUVIUM
ML
SANDY SILT: Whitish gray, very fine
1
(Qal)
9
grained sand, dry, medium stiff.
9
9
i
i
SP/SM SAND/SILTY SAND: Light gray, fine
grained, dry, medium dense.
2
15
NR
25
TOTAL DEPTH AT 30'
NO GROUND WATER j
{
14
I ( i
j EASY DRILLING
-
17
I I
19
BORING BACKFILLED I
•
•
GEOTECHNICAL BORING LOG
Date 1/21/91 Drill Hole No. B-6 Sheet 1 of 1
Project Name Birtcher/Washington Square Project No. 6901579-01
Drilling Co. Datum Type of Rig CME 75/All Terrain
Hole Diameter 8" Drive Weight 140 lbs. Drop 30" Elevation --
Depth/
Feet
Earth
Material
Type
of
Test
Tube
Samp.
Test
Blows
per
6 -inch
Dry '
Dens.
pcf
Mois.
Cont.
%
Soil
Class
USCS
GEOTECHNICAL DESCRIPTION
Logged by DG
Sampled by DG
WIND
SP
SAND: Gray, fine grained, dry, j
BLOWN
loose.
SANDS
(Qwbs)
i
12
97
1
11
Medium dense.
8
13
1
20
SP/SM
Slight silt content.
`
Occasional layers of silty sand.
GS
8
97
1
1
SE =
63
16
Percent Passing No. 200 Sieve = 9.
8
12
18
20
With layers of thinly laminated silt.
TOTAL DEPTH AT 25'
NO GROUND WATER
EASY DRILLING
�j
16
BORING BACKFILLED
19
2
GEOTECHNICAL 6URING LOG
Date 1/21/91 Drill Hole No. B-7 Sheet 1 of 1
Project Name Birtcher/Washington Square Project No. 6901579-01
Drilling Co. Datum Type of Rig CME 75/All Terrain
• ole Diameter 8" Drive Weight 140 lbs. Drop 30" Elevation --
Type Tube Blows Dry Mois. Soil GEOTECHNICAL DESCRIPTION
Depth/ Earth of Samp. per Dens. Cont. Class Logged by DG
Feet Material Test Test 6 -inch pcf ro USCS Sampled by DG
WIND SM SILTY SAND: Light brown, fine
BLOWN grained, dry, loose.
SANDS
(Qwbs)
CP 6 84 3
8 (73)
I
•
5
6
9
6 88 2
18 (77)
1
11
22 SP/SM SAND/SILTY SAND: Gray, fine grained,;
24 dry, dense. I
2
TOTAL DEPTH AT 25'
NO GROUND WATER
• EASY DRILLING
• 1 2
BORING BACKFILLED
•
•
J
120
V)
z 110
0
a
64
F -
MOISTURE CONTENT IN PEP.CENT OF DRY WFIGIIT
5 10 15 20
Zero Air Vofi ds
2.50
100
LOCATION
Boring or Test Pit B-2
Depth, in Feet 1-3
Representative For Wind Blown Sands (Qwbs)
SOIL CLASSIFICATION
Grain Sizes in Percent of Dry Weight
Coarse (Retained on #200 Sieve) --
Fines (Passing #200 Sieve) --
Atterberg limits, in Percent of Dry Weight
Liquid Limit --
Plasticity Index --
Soil Type and Description SAND/SILTY SAND (SP/St-1) : Light brown, fine grained.
COMPACTION PROPERTIES
Method of Compaction
ASTM Standard Test Method D1557-18 Equivalent to A.A.S.H.T.O.
Soil Compaction Test T180-57 (1/30 Cubic Foot Mold 10 Pound Hammer
Falling 18 inches, 25 Blows Per Layer)
Optimum Moisture Content, in Percent of Dry Weight 14.0
Maximum Dry Density, in Pounds per Cubic Foot 111.0
Project tlo.. 6901579-01 Plate No. C-3
LEIGHTON AND ASSOCIATES, INC.
•
MOISTURE CONTENT. IN PERCENT OF DRY WEIGHT
5 10 ; 15 20
125
120
Zero Air oids
/ G=2 70
115
110
25
105
LOCATION
Boring or Test Pit B-7
Depth, in Feet 1-4
Representative For Wind Blown Sands (Qwbs)
SOIL CLASSIFICATION .
Grain Sizes in Percent of_Ory Weight
Coarse (Retained on #200 Sieve) --
Fines (Passing #200 Sieve) --
Atterberg limits, in Percent of Dry Weight
Liquid Limit --
Plasticity Index --
Soil Type and Description SILTY SAND (SP1): Light
brown, fine grained.
COMPACTION PROPERTIES
Method of Compaction
ASTM Standard Test Method D1557-78 Equivalent
to A.A.S.H.T.O.
Soil Compaction Test T180-57 (1/30 Cubic Foot
Mold 10 Pound Hammer
Falling 18 inches, 25 Blows Per Layer)
Optimum Moisture Content, in Percent of Dry Weight
16.0
Maximum Dry Density, in Pounds per Cubic Foot -
114.5
Project No. 6901579-01 Plate No. C-4
LEIGHTON AND ASSOCIATES, INC.
6901519-01
be overexcavated as specified in the following section.
Scarification shall continue until the soils are broken down and
Free of large clay lumps or clods and until the working surface is
reasonably uniform and free of uneven features which would inhibit
uniform compaction.
3.3 Overexcavation: Soft, dry, spongy, highly fractured or otherwise
unsuitable ground, extending to such a depth that surface processing
cannot adeouately improve the condition, shall be overexcavated down
to firm ground, approved by the consultant.
3.4 Moisture Conditioning: Overexcavated and processed soils shall be
watered, dried -back, blended, and/or mixed, as required to attain a
uniform moisture content near optimum.
3.5 Recompaction: Overexcavation and processed soils which have been
properly mixed and moisture -conditioned shall be recompacted to a
minimum relative compaction of 90 percent.
3.6 Benching: Where fills are to be placed on ground with slopes steeper
than 5:1 (horizontal to vertical units), the ground shall be stepped
or benched. The lowest bench shall be a minimum of 15 feet wide,
shall be at least 2 feet deep, shall expose firm material, and shall
be approved by the consultant. Other benches shall be excavated in
firm material for a minimum width of 4 feet. Ground sloping flatter
than 5:1 shall be benched or otherwise overexcavated when considered
necessary by the consultant.
3.7 Approval: All areas to receive fi'l'l, including processed areas,
• removal areas and toe -of -fill benches shall be approved by the
consultant prior to fill placement.
4.0 Fill Material
•
4.1 General: Material to be placed as fill shall be free of organic
matter and other deleterious substances, and shall be approved by
the consultant. Soils of poor gradation, expansion, or strength
characteristics shall be placed in areas designated by consultant or
shall be mixed with other soils to serve as satisfactory fill
material.
4.2 Oversize: Oversize material defined as rock, or other irreducible
material with a maximum dimension greater than 12 inches, shall not
be buried or placed in fills, unless the location, materials, and
disposal methods are specifically approved by the consultant.
Oversize disposal operations shall be such that nesting of oversize
material does not occur, and such that the oversize material is
completely surrounded by compacted or densified fill. Oversize
material shall not be placed within 10 feet vertically of finish
grade or within the range. of future utilities or underground
construction, unless specifically approved by the consultant.
I
WJUlSi9-U1
4.3 Import: If importing of fill material is required for grading, the
import material shall meet the requirements of Section 4.1.
• 5.0 Fill Placement and Compaction
5.1 Fill Lifts: Approved fill material shall be placed in areas prepared
to receive fill in near -horizontal layers not. exceeding 6 inches in
compacted thickness. The consultant may approve thicker lifts if
testing indicates the grading procedures are such that adequate
compaction is being achieved with lifts of greater thickness. Each
layer shall be spread evenly and shall be thoroughly mixed during
spreading to attain uniformity of material and moisture in each
layer.
•
5.2 Fill Moisture: Fill layers at a moisture content less than optimum
shall be watered and mixed, and wet fill layers shall be aerated by
scarification or shall be blended with drier material. Moisture -
conditioning and mixing of fill layers shall continue until the fill
material is at a uniform moisture content at or near optimum.
5.3 Compaction of Fill: After each layer has been evenly spread,
moisture- conditioned, and mixed, it shall be uniformly compacted to
not less than 90 percent of maximum dry density. Compaction
equipment shall be adequately sized and shall be either specifically
designed for soil compaction or of proven reliability, to
efficiently achieve the pecified degree of compaction.
5.4 Fill Slopes: Compacting of slopes shall be accomplished, in addition
to normal compacting procedures, by backrolling of slopes with
sheepsfoot rollers at frequent increments of 2 to 3 feet in fill
elevation gain, or by.other methods producing satisfactory results.
At the completion of grading, the relative compaction of the slope
out to the slope face shall be at least 90 percent.
5.5 Compaction Testing: Field tests to check the fill moisture and
degree of compaction will be performed by the consultant. The
location and frequency of tests shall be at the consultant's
discretion. In general, the tests will be taken at an interval not
exceeding 2 feet in vertical rise and/or 1,000 cubic yards of
embankment.
6.0 Subdrain Installation
Subdrain systems, if .required, shall be installed in approved ground to
conform to the approximate alignment and details shown on the plans or
herein. The subdrain location or materials shall not be changed or
modified without the approval of the consultant. The consultant, however,
may recommend and upon approval, direct changes in Subdrain line, grade or
material. All subdrains should be surveyed for line and grade after
installation and sufficient time shall be allowed for the surveys, prior
to commencement of filling over the subdrains.
0-3
OJU1J/y-U1
1.0 Excavation
Excavations and cut"),sl'opes will be exarrinediduring grading. If directed
• by the consultant,''further excavation or overexcavation and refilling of
cut areas shall be performed, and/or remedial grading of cut slopes shall
be performed. Where fill -over -cut slopes are to be graded, unless
otherwise approved, the cut portion of the slope shall be made and
approved by the consultant prior to placement of materials for
construction.of the fill portion of the slope.
8.0 Trench Backfills
` 8.1 Trench excavations for utility pipes shall be backfilled under
engineering supervision.
8.2 After the utility pipe has been laid, the space under and around the
pipe shall be backfilled with clean sand or approved granular soil
to a depth of at least one foot over the top of the pipe. The sand
backfill shall be uniformly jetted into place before the controlled
backfill is placed over the sand.
8..3 The onsite materials, or other soils approved by the soil engineer,
shall be watered and mixed as necessary prior to placement in lifts
over the sand backfill.
8.4 The controlled backfill shall be compacted to at least 90 percent of
the maximum laboratory density as determined by the ASTM compaction
method described above.
• 8.5 Field density tests and inspection of the backfill procedures shall
be made by the soil engineer during backfilling to see that proper
moisture content and uniform compaction is being maintained. The
contractor shall provide test holes and exploratory pits as required
by the soil engineer to enable sampling and testing.
•
0-4
U21 JV/ LVV`f 1L.:J7 f LYYYYLSLG
FW -12 -EM 15:44 FROM:
r\G.11 Ljr%",RJ - V rev . .-..d --
T0:171 122 P.1
REQUEST FOR INFORMATION
Attn: kA—f,
41^E1•Z.lp2
RFI No. 2 0
Project: OFFICE DEPOT
WASHINGTON PARK
78.987 Highway 144
LA QUINTA, CA 92253
033SZ
00REFtELO
ONSTRUCTlON, INC.
K /,/-
DATE FMWWLED: � Oaf INFORMATION
NEEDED w. AS AV
INFORMATION RECUSSTED BY: �bA!@ _ j�AE 444,i 1 T%4.,�� C -'"1'T -i -'t
ITEM -0
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The sbw& pg4usat tar in%nnaam rggWm Immsdiab �ttion to unable Momeftfd Co ne,
9 could Ind to an
to eanple�l aonatrvet�n by tna sWfsdutad eoenpladoe dd& Dais>ra to rsspoa►d1i10
s�ctsisd+e cwnplallon dam. Your prompt aftnuar0a appreclGIB , RF14161
I
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