HomeMy WebLinkAboutCT 02-29; CASA LA COSTA; PROJECT GRADING REPORT LOT 11; 2010-10-15I ADVANCED GEOTECIINICAL SOLUTIONS* INC
I 1 1 25220 Hancock Avenue, Suite 420 J: : Mu'rieta, California 925:62
\ / Telephone (619)708-1649 Fax (714)409-3287
I :NEW PoINTE:coMMUNITLEs,'INc .**. H October 15, 2010.
16880 West Bemardo Drive, Suite 230 P/W 1004-02
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San Diego, CA 92127 Report No 1004-02-C-4 .. ....
Attention Mr Scot Sandstrom
I Subject Project Grading Report Proposed Condominium, Lot 11, Villas de La Costa,
Carlsbad,: California: : . : I . : H
References 1) Geotechnical Response to Review Comments from the City of Carlsbad for Proposed
Condominium Lot 11 Villas de La Costa Carlsbad California prepared by Advanced
I Geotechnical Solutions Inc.,dated August 11 2010 (P7W 1004-02)
2) Geotechnical Investigation and Foundation Design Recommendations for Proposed
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Condominium Lot 11 Villas de La Costa California prepared by Advanced
Geotechnical Solutions Inc.,dated June 23 2010 (P1W 1004-02)
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Gentlemen .. . . . .....
In accordance -with your request .presented herein is Advanced Geotechnical. Solutions, Inc (AGS),
I observations and test results pertammg to the recently completed grading of the subject Proposed
Condominium, Lot 11, Villas de La Costa, Carlsbad, California Based on the results of the testmg and
observations by representatives of AGS, the work dehereinbed here is considered to be in general
conformance with City. of Carlsbad, Grading Code, the recommendations presented in the referenced
geotechnical report and is considered suitable for its :intended use
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This report addresses gradmg operations aimed at attaining rough grades for the subject lot as reflected on
the site plan prepared' reparde by Hunsaker and Associates Rough gradmg for the subject site was conducted m
October 2010 Soil engmeermg observations collected durmg rough gradmg are summarized m the text of
I this report and the developed data are presented m Table I The approximate locations of compaction
tests and limits of fill under the purview of this report are shown on the accompanying Site Plan for Lot
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11, Villas de La Costa (Plate 1)
O• GEOLOGY....... . .: .. . •••••••. ••• • :
A brief description of the earth materials encountered on the subject site is presented m the followmg
sections Based on our observations ::during the recent gradmg, site reconnaissance, subsurface
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excavations, and review of geologic maps, the site is underlam to the depths explored by Santiago
formation deposits which are locally overlam by 15 to 15 feet of various phases of previously placed fill
I . . 1.1. Artificial Fill (at) . : • H • H :
During this recent phase of gradmg the upper 18-inches of existmg surface was removed
prior to fill placement The exposed bottom was ripped, moisture conditioned and
I compacted to a minimum' of 90% of the laboratory maximum density Additional fill
ORANGE AND LA..: COUNTIES INLAND EMPIRE SAN DIEGO AND IMPERIAL COUNTIES
1 (714) 786-5661 (619) 708-1649 (619):850-MO
October 15, 2010 Page 2
I .P1W 100402 Report No. 1004-2-C-4
generated from onsite sources were then placed and compacted in succeeding lifts until
the final grades were achieved.
1.2. Artificial Fill (afu)
I. Artificial fill soils were encountered in the previously conducted borings and observed to
overlie the Santiago Formation. The fill soils were of variable thickness, ranging from
approximately 3.5 feet to 15.0 feet. As encountered, the fill generally, consisted of brown 1 . to reddish brown to gray, slightly moist to moist, loose to medium dense, silty to clayey
sand and firm, sandy clay.
I 1.3. Santiago Formation (Ts)
The site is underlain to maximum depth explored .by Santiago Formation. As encountered
I .in our exploratory excavations, these materials can generally be described as green to
gray 'green, slightly moist to moist, stiff to hard, silty claystone.
' 1.4. Groundwater
Groundwater was not encountered during grading of the site nor was it encountered in the
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recent Geotechnical Investigation (AGS' 6/23/10). No natural groundwater condition is
known to exist at the site that would impact the proposed site development. Although.
unlikely, localized perched groundwater could develop at a later date, most likely at or
I near fill/bedrock contacts or in coarser zones in the bedrock, due to fluctuations in
precipitation, irrigation practices, or factors not evident at the time of our field work.
2.0 GRADING
Presented herein is a summary of observations collected during grading. The subject site appears to have
.I been sheet graded approximately 10 to 15 years ago. Since that time the subject site supported a
temporary Fire Statioti vacant and supported a light growth of grass and ice plant. Prior to the
'commencement of grading operations, all onsite surface vegetation, and debris piles were removed from
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the Site.
Based on AGS's referenced geotechnical report, it was concluded that remediation of the upper 18 - ' inches of the existing surface soils would be required during., site grading operations to provide a suitable
building pad for support of flatwork and other non-essential structures. Ultimately the structure will be
supported by a. Post-Tensioned slab supported by a. Cast-In-Drilled-Hole (CIDH) pile foundation.
I Presented herein is a Summary of the removal and fill placement operations.
2.1. Unsuitable Soil Removals
I Grading for the subject lot consisted of fine grading of the lot to the design grade
depicted on the Site Plan Lot 11, Villas de La Co'ta (Plate 1) , prepared by Hunsaker and
I Associates. Prior to placing any fill on the site, dry, loose, and compressible preexisting
artificial fill soils were removed -to expose undocumented fill. Where possible, removal
limits extended horizontally a minimum of five feet outside the structural footprint of the
I proposed condominium structure
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The maximum depth of fill under the purview of this report is approximate1y30-inches.
1 2 2 Compaction Operations
The excavation bottoms were observed by a representative of this firm after the I completion of removals The exposed soils were then scarified to an approximate depth
of 4 to 6 inches, brought to above optimum moisture content and compacted in-place to a
I minimum of 90 percent of the laboratory maximum dry density in accordance with
ASTM Test Method D-1557. Fill materials, consisting of the soil types summarized in
Table I, were then placed in thin, loose, 'lifts: (approximately '8 inches), brought to slightly
I above optimum moisture content, and compacted to a minimum of 90 percent of the
laboratory maximum dry density in accordance with ASTM Test Method D-1557.
Compaction was achieved by equipment wheel rolling.
Compaction tests were taken during the course of grading for every one to two feet of fill
placed A summary of compaction tests pertaining to gradmg within the subject lot is
presented in Table I. The approximate locations of these tests are shown on the I accompanying plan (Plate 1).
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3.0 DESIGN -RECOMMENDATIONS
Based on AGS's recent observations and review of the referenced report, the lot is considered suitable for
support of the proposed condominium From a geotechmcal viewpoint, the proposed structure for the I subject lot can be constructed at this time. The foundations for the subject lots should be constructed in
general conformance with the recommendations presented in the referenced reports and the following:
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3.1. Expansion Potential
Expansion Index (El) testing in accordance with ASTM D 4829 was conducted on a
representative sample of the onsite soils Test results indicate that the near surface soils
on 'the building pad exhibited an expansion index of 92, which corresponds to a "High"
expansion potential per CBC 2007.
3.2. Foundation Desun Cntena ' It is our understanding that the proposed foundation will consist of either a post-tensioned
or" "Mat" slab supported by a pier foundation system founded in bedrock. Specific
foundation design criteria are presented as follows:
I ' Mat Slab
Slab Allowable Bearing 500 lbs /sq ft allowable bearing for the mat or
post tensioned slab on prepared grade
Total Settlement: Total = 3/8 inch
I Differential: 3/8 inch in 20 feet
Sliding Coefficient: 0.25
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. . Report No.1004-2-C-4
The.,above values may be increased as allowed by Code to resist transient loads such as
I -wind or seismic. Building 'Code and structural design considerations may govern. Depth
and reinforcement requirements should be evaluated by the Structural Engineer.
Pier Foundations
> Pier Design:
Pier design values are presented, for 24 inch diameter. piers. Results of our
analysis are presented on Tables C-2 and the Allowable Load vs. Depth is
presented on Figure 4. This figure is for embedment into bedrock only; Piles
capacity is presented in table C-2 with Figure 4depicting the pile. capacity vs.
embedment curve for the proposed 24-inch diameter piles; Our analysis assumed
the piles would generate capacity from both friôtion and end bearing. The bottom
of the CIDH pile excavation should' be clean and free of loose debris and should
expose competent bedrock. Should the method of construction (i.e. failure to
adequately clean the bottom' of the excavation) or, the strength/type of bearing
material be different than what was assumed in developing the axial capacity
curves, the excavation for the CIDH piles may need to be deepened. For analysis
of the allowable capacity of the piles a factor of Safety FS=1.75 was utilized.
Final determination of factor of safety for piles should be determined by the
project structural engineer based upon code, and the current standard of care.
> Minimum Pier Embedment:
The piers should be embedded a minimum of six pile diameters into bedrock and
no vertical load resistance will be provided in the portion of the piers situated in
the undocumented fill.
> Group Efficiency:
Provided that piers are placed no closer than 3 pile diameters no group efficiency
reduction will be required.
> Pile Installation Considerations:
Difficult drilling, seepage and some caving should be expected while drilling the
CIDH piles. The installation method and specifications should be reviewed by
the Geotechñical Engineer prior to construction. As a minimum, the installation
of the CIDH piles should conform to AC! 336.1, Specifications for the
Construction of , Drilled Piers. Alternative construction methods can be
considered subject to the approval of the Geotechnical Engineer.
> Observation During Construction
Observation by the Geotechnical Engineer of Record will be necessary during
excavation of each of the CIDH piles to evaluate the depth of bedrock.
3.3. SeismicDesign Criteria
The 'following seismic design parameters are presented to be code compliant to the
California Building Code (2007). The subject lot has been identified to be site class "C"
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I P1W 1004-02 Report No. 1004-2-C-4
in accordance with CBC, 2007, Table 1613.5.3 (1).' The lot is Latitude 33.0814 N and
I LOngitude 117;2387*. W. . Utilizing this information, the computer program USGS
Earthquake Ground Motion Parameters Version 5.0.7 and ASCE 7 criterion, the seismic
design category for 0.20 seconds (S5) and 1.0 second (S1) period response accelerations
I can be determined (CBC, 2007 1613.5.5.1) along with the design spectral response
acceleration (CBC, 2007 1613.5.4).
Seismic Design Criteria
Mapped Spectral Acceleration (0.2 sec Period), Ss 1.130g
Mapped Spectral Acceleration (1.0 sec Period), Si 0.424
Site Coefficient, Fa 1.0
Site Coefficient, F 1.376
MCE Spectral Response Acceleration (0.2 sec Period), SM5 1.130g
MCE Spectral Response Acceleration (1.0 sec Period), SM1 0.584g
Design Spectral Response Acceleration (0.2 sec Period), Sbs 0.754g
Design Spectral Response Acceleration (l .*0 sec Period), SDI 0.389g
3.4. Under Slab
The subgrade soils should be moisture conditioned to a minimum of 130610 of optimum
moisture to a depth of 12 to 18 inches below finish grade a minimum of 48-hours prior to
concrete. placement.
A moisture and vapor retarding system should be placed below the slabs-on-grade in
portions of the structure considered to be: moisture sensitive. The retarder should be of
suitable composition, thickness, strength and low permeance to effectively prevent the
migration of water and reduce the transmission of water vapor to acceptable levels.
Historically, a 10-mil plastic membrane, such as Vis queen, placed between one to four
inches. of clean sand, has been used for this purpose. More recently Stego® Wrap Or
similar underlayments have been used to lower permeance to effectively prevent the
migration of water and reduce the transmission of water vapor to acceptable levels. The
use of this system or other systems, materials or techniques can be considered, at the
discretion of the designer,. provided the system reduces the vapor transmission rates to
acceptable levels.
3.5. Concrete Design
Preliminary testing conducted previously by PSE indicates onsite • soils exhibit a
"Moderate" to "Severe" sulfate exposure when classified in accordance with ACI 318-05
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Table 4.3. 11 (per 2007 CBC). Accordingly, concrete used for the foundation construction
I.. should be designed to accommodate a "Severe" sulfate exposure. Typically, this will
require a 4,500 psi concrete, utilizing a 0.45 maximum water-cement ratio (by weight)
and a Type "V" Cement concrete.
I . 3.6. Corrosion .
I . Preliminary testing conducted previously by PSE indicates onsite soils exhibit a
"Moderate" to "Severe" sulfate exposure when classified in accordance with ACI 318-05
Table 4.3.1 (per 2007 cBc). Accordingly, concrete used for the foundation construction
I should be designed to accommodate a "Severe" sulfate exposure. Typically, this will
require a 4,500 psi concrete, utilizing a 0.45 maximum water-cement ratio (by weight)
and a Type "V" Cement concrete.
3.7. Retaining Walls
The following earth pressures are recommended for the design of retaining walls onsite:
Rankine Equivalent Fluid
Rankine Equivalent Fluid
I .Level Backfill Coefficients Pressure (psf/lin.ft.)
Coefficient Of Active Pressure: Ka = 0.31 38
Coefficient of Passive Pressure: K =3.25 407
Coefficient of at Rest Pressure: I( = 0.47 59
Rankine Equivalent Fluid
2: 1 Backfill Coefficients Pressure (p5f/lin.ft.),
Coefficient of Active Pressure: Ka = 0.47 59
Coefficient of Passive Pressure:
Descending K (-) = 1.23 154
Coefficient of At Rest Pressure: K. = 0.72 90
The foundations for retaining walls of appurtenant structures structurally separated from
fl .
the, building structure may bear on properly compacted fill. A bearing value of 2,000 psf
may be used for design of retaining walls. Retaining wall footings should be designed to
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resist the lateral forces by passive soil resistance and/or base friction as recommended for
foundation lateral resistance. To minimize the potential for hydrostatic pressure, wall
backfill should consist of a free draining backfill (sand equivalent "SE" >20) and a heel
I . drain should be constructed. The heel drain should be place at the heel of the wall and
should consist of a 4-inch diameter perforated pipe (SDR35 or SCHD 40) surrounded by
4 cubic feet of crushed rock (3/4-inch) per lineal foot wrapped in filter fabric (with
I similar properties-to Mirafi 140N or equivalent). .
Proper drainage devices should be installed, along the top of the wall backfill and should
properly slope to prevent surface water ponding adjacent to the wall. In addition to the
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3.9. Utility Trench Backfill
Mainline and lateral utility trench backfill should be compacted to at least 90 percent of
maxinum dry density as determined by. ASTM: D- 1557. Onsite soils may not be suitable
for use as bedding material but will be suitable for use in backfill, provided oversized
materials are removed. No surcharge k)ads should be imposed above excavations. This
includes spoil piles, lumber, concrete trucks or other construction, materials and
equipment. Drainage above excavations shoUld be directed away from the banks. Care
should be taken to avoid saturation of the. soils.
Compaction should be accomplished by mechanical means. Jetting of native soils will
j not be acceptable.
3.10. Exterior Slabs and Walkways
3i0i. Subgrade Compaction
I The subgrade below exterior slabs, sidewalks, driveways, patios,. etc. should be
compacted to a minimum of 90 percent relative compaction as determined by ASTM Test
Method: D 1557.
3.10.2. Subgrade Moisture
The subgrade below exterior slabs, sidewalks, driveways, patios, etc should be moisture
conditioned to a minimum of 130 percent of optimum moisture content prior to concrete
placement.
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3103 Slab Thickness .
Concrete flatvork and driveways should be designed utilizing four-inch minimum
thickness. A thickened edge (scoop footing) is recommended for concrete flatwork
approximately. six inches wide and extending six to eight inches below the slab
3.10.4. Control Joints
Weakened plane joints should be installed on walkways at intervals of approximately
eight to ten feet. Exterior slabs should be designed to withstand shrinkage of the
concrete. .
3.10.5,. Flatwork Reinforcement
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Consideration should be given to reinforcing any exterior flatWork with No. 6 by No. 6
Welded Wire Mesh.
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3.10.6. Under Slab Treatment
1 Consideration should be given to under laying concrete flatwork with approximately four
inches of a non expansive soil (sand, aggregate base or crushed rock) to help minimize
detrimental movement caused by the underlying expansive soils.
- 3.10.7. Thickened Edge
I Consideration should be given to construct a thickened edge (scoop footing) at the
perimeter of slabs and walkways adjacent to landscape areas to minimize moisture
variation below these improvements. The thickened edge (scoop footing) should extend
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approximately eight inches below concrete slabs and should be a minimum of six inches
- wide.
4.0 LIMITATIONS
This report presents information and data relative to onsite construction operations for the subject site. A
representative(s) of this firm probed and tested at random locations in an effort to determine whether
compliance with the project compaction, specifications, and applicable Building Code was being
obtained. The presence of our personnel during testing operations does not involve any supervision or
direction of the contractor or his work forces.
AGS should be notified of any pertinent changes in the project plans or if subsurface, conditions are found
to vary from those described herein. Such changes or variations may require a re-evaluation of the
recommendations contained in this report. The data, opinions, and recommendations of this report are
applicable to the specific design of this project as discussed in this report. They have no applicability to
any other project or to any other location, and any and all subsequent users accept any and all liability
resulting from any use or reuse of the data, opinions, and recommendations without the prior written
consent of AGS.
AGS has no responsibility for construction means, methods, techniques, sequences, or procedures, or for
I, safety precautions or programs in connection with the construction, for the acts or omissions of the
CONTRACTOR, or any other person performing any of the construction, or for the failure of any of them
to carry out the construction in accordance with the final design drawings and specifications.
I, The opportunity-to be of service is sincerely appreciated. If you should have, any questions, please do not
hesitate to contact the undersigned.
Respectfully Submitted, I Mvae4 Geotechniça4-Slutions, Inc.
AIRIVY A'>lC1TNEY/\Tice Presidet PAUL J. DERISI, Vice President
46554!RGE 23 1 Reg. Exp.fi40-1 1 CEG 2536, Reg. 'Exp. 5-31-11
Distribution: ' (6) Ar
De L
OFE5SiO Figure 4 (Pile Capacity vs. Embedment Curve) 01
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Table C-2 (Pile Capacity)
: 234m
Table I (Compaction Test Table) CERTIFIED
late I (Geologic Map, and Compaction Test Location Plan) II I ENGINEERING
\ \ GEOLOGIST / 0
fl)omeoers
Maintenance Recommendations
ADVANCED GEOTECHNICAL SOLUTIONS, INC. OF CAL\
- - - - - M ilo - - - - - - - - - - - - Table C-2
Pile Capacity Calculation 24-Inch-Diameter Date: 6/23/2010
By: jac,
Location: Villas La Costa
Type of Pile: ClDH
Pile Diameter D (ft): 2.0
Effective Unit Weight y' (k/ft3): 0.126
Friction Angle, degrees,': 25.0.
0 (see below): 0.80
K (see below): 0.50
Cohesion c (ksf): 0.5
Adhesion Coefficient k: 0.55
Allowable Tip Bearing (kips) 10
Depth to Bedrock (ft): 0.0
Factor of Safety: 1.75
Tip Resistance (kips): 18
dZ=lncrement of Pile Length (ft)
Z=Depth to Center of Inc. of Pile Length (ft)
PAN 1004-02
Sheet:
Qtip= *rA2*Qat
F.S.
Qs(f)= E7r*D*dZ*y*Z*K*tan4
F.S.
Qs(c)= *D*dZ*Z*k*c
F.S.
Depth (ft)
(ft)
A5
Perimeter
Area
(ft/ft)
dZ
increment
of Length
(ft)
1'%
Increment
of Area
,A*D*dz
Z
EffectivE
Depth
(ft)
Y
Effective
Unit Weight
k/ft3
a' tan 5' K S
Shaft Friction + Adhesion
Sy*Z*k*tan + k*c(klft2)
AQ
1Q..A*S
EQ
EQ=EiQ
Q8
Safe Cap.
Q5=EQIF.S
Quit
Tip+Shaft
(kips)
5 - 6.28 5 31.42 2,5 0.13 20.00 0.36 0.50 0.33 10.44 10.44 5.97 23.9 10 6.28 5 31.42 7.5 0.13 20.00 0.36 0.50 0.45 14.04 24.48 13.99 31.9 15 6.28 5 31.42 12.5 0.13 20.00 0.36 0.50 0.56 . 17.64 42.13 24.07 42.0 20 6.28 5 31.42 17.5 0.13 20.00 0.36 0.50 0.68 21.25 63.37 36.21 54.2 25 6.28 5 31.42 22.5 0.13 20.00 0.36 0.50 0.79 24.85 88.22 50.41 68.4 30 6.28 5 31.42 27.5 0.13 20.00 0.36 0.50 . 0.91 28.45 _116.67 66.67 84.6 35 6.28 5 31.42 32.5 0.13 20.00 0.36 0.50 1.02 32.05 148.72 84.98 102.9 40 6.28 5 31.42 37.5 0.13 20.00 0.36 0.50 1.13 35.65 184.37 105.35 123.3 45 6.28 5 31.42 42.5 0.13 20.00 0.36 0.50 1.25 39.25 223.62 127.78 145.7 50 6.28 5 31.42 47.5 0.13 20.00 0.36 0.50 1.36 42.86 266.48 152.27 170.2 55 6.28 . 5 31.42 52.5 0.13 20.00 0.36 0.50 1.48 46.46 312.94 178.82 196.8 60 . 6.28 5 31.42 57.5 0.13 20.00 0.36 0.50 1.59 50.06 363.00 207.43 225.4 ( 65 6.28 5 31.42 62.5 0.13 20.00 0.36 '0.50 1.71 5166 416.66 238.09 256.0 70 6.28 5 31 67.5 0.13 20.00 0.36 0.50 1.82 57.26 473.92 270.81. 288.8
- 75 6.28 5 31 72.5 0.13 20.00 0.36 0.50 1.94 . 60.86 534.78 305.59 323.5 80 1 6.28 5 31.42 77.5 0.13. 20.00 0.36 1 0.50 1 2.05 64.47 599.25 342.43 360.4 85 1 6.28 1 5 31.42 82.5 0.13 20.00 L0.36 1 0.50 1 2.17 68.07 667.32 381.32 399.3 90 6.28 1 5 1 31.42 87.5 0.13 20.00 1 0.36 1 0.50 1 2.28 71.67 738.99 422.28 440.2
3= 0.6 for Steel K= Condition of Sand 12" Pipe Timber (14' Bu#) Precast (12") Step-Taper H-Pile Cast-in-Place
0.75 for Driven Concrete L Loose 4=25 0.7 1.1 0.75 1.2 0.7 0.5
0.8 for Cast-in-Place Concrete L Dense =35 1.1 2.0 1.3 2.2 1.1 0.55
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HOMEOWNER MAINTENANCE AND IMPROVEMENT CONSIDERATIONS
I Honieowners are accustomed to maintaining their homes. They expect to paint their houses periodically,
replace wiring, clean out clogged plumbing, and repair roofs. Maintenance of the home site, particularly on
I hillsides, should be considered on the same basis or even on.a more serious basis because neglect can result in
serious consequences In most cases, lot and site maintenance can be taken care of along with .landscaping,
and can be carried out more economically than repair after neglect.
Most slope and hillside lot problems are associated with water. Uncontrolled water from a broken pipe,
cesspool, or wet weather causes most damage. Wet weather is the largest cause of slope problems, particularly
in California where rain is intermittent, but may be torrential. Therefore, drainage and erosion control are the
most important aspects of home site stability; these provisions must not be altered without competent
professional advice. Further, maintenance must be carried out to assure their continued operation.
I ' As geotechnical engineers concerned with the problems of building sites in hillside developments, we offer
the following list of recommended home protection measures as a guide to homeowners.
I Expansive Soils
Some of the earth materials on site have been identified as being expansive in nature. As such, these
materials are susceptible to volume changes with variations in their moisture content. These soils will swell
upon the introduction of water and shrink upon drying. The forces associated with these volume changes can
have significant negative impacts (in the form of differential movement) on foundations, walkways, patios,
and other lot improvements. In recognition of this, the project developer has constructed homes on these lots
on post-tensioned or mat slabs with pier and grade beam foundation systems, intended to help reduce the
potential adverse effects of these expansive materials on the residential structures within the project. Such
I foundation systems are not intended to offset the forces (and associated movement) related to expansive soil,
but are intended to help soften their effects on the structures constructed thereon.
Homeowners purchasing property and" living in an area containing expansive soils must assume a certain
I degree of responsibility for homeowner improvements as well as for maintaining conditions around their
home. Provisions should be incorporated into the design and construction of homeowner improvements to
I account for the expansive nature of the onsite soils material. Lot maintenance and landscaping should also be
conducted in consideration of the expansive soil characteristics.' Of primary importance is minimizing the
moisture variation below all lot improvements. Such design, construction and homeowner maintenance
I provisions should include:
. Employing contractors for homeowner improvements who design and build in recognition of local
I :building code and site specific soils conditions.
. Establishing and maintaining positive drainage away from all foundations, walkways, driveways,
patios, andóther hardscape improvements.
I + Avoiding the construction of planters adjacent to structural improvements. Alternatively, planter
sides/bottoms can be sealed with an impermeable membrane and drained away from the improvements via
subdrains into approved disposal areas.
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.:. Sealing and maintaining construction/control joints within concrete slabs and walkways to reduce the
potential for moisture infiltration into the subgrade soils.
+ Utilizing landscaping schemes with vegetation that requires minimal watering. Alternatively,
watering should be done in a uniform manner as equally as possible on all sides of the foundation, keeping the
I soil "moist" but not allowing the soil to become saturated.
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ADVANCED GEOTECIINICAL SOLUTIONS, INC.
+ Maintaining positive drainage away from structures and providing roof gutters on all structures with
downspouts installed to carry roof runoff directly into area drains or discharged well away from the structures.
+ Avoiding the placement of trees closer to the proposed structures than a distance of one-half the
mature height of the tree.
. Observation of the soil conditions around the perimeter of the structure during extremely hot/dry or
unusually wet weather conditions so that modifications can be made in irrigation programs to maintain
relatively constant moisture conditions.
Sulfates
Homeowners should be cautioned against the import and use of certain fertilizers, soil amendments, and/or
other soils from offsite sources in the absence of specific information relating to their chemical composition.
Some fertilizers have been known to leach sulfate compounds into soils otherwise containing "negligible"
sulfate concentrations and increase the sulfate concentrations in near-surface soils to "moderate" or "severe"
levels. In some cases, concrete improvements constructed in soils containing high levels of soluble sulfates
may be affected by deterioration and loss of strength.
Water - Natural and Man Induced
Water in concert with the reaction of various natural and man-made elements, can cause detrimental effects to
your structure and surrounding property. Rain water and flowing water erodes and saturates the ground and
changes the engineering characteristics of the underlying earth materials upon saturation. Excessive irrigation
in concert with a rainy period is commonly associated with shallow slope failures and deep seated landslides,
saturation of near structure soils, local ponding of water, and transportation of water soluble substances that
are deleterious to building materials including concrete, steel, wood, and stucco.
Water interacting with the near surface and subsurface soils can initiate several other potentially detrimental
phenomena other then slope stability issues. These may include expansion/contraction cycles, liquefaction
potential increase, hydro-collapse of soils, ground surface settlement, earth material consolidation, and
introduction of deleterious substances.
The homeowners should be made aware of the potential problems which may develop when drainage is
altered through construction of retaining walls, swimming pools, paved walkways and patios. Ponded water,
drainage over the slope face, leaking irrigation systems, over-watering or other conditions which could lead to
ground saturation must be avoided.
Before the rainy season arrives, check and clear roof drains, gutters and down spouts of all
accumulated debris. Roof gutters are an important element in your arsenal against rain damage. If you do not
have roof gutters and down spouts, you may elect to install them. Roofs, with their, wide, flat area can shed
tremendous quantities of water. Without gutters or other adequate drainage, water falling from the eaves
collects against foundation and basement walls.
Make sure to clear surface and terrace drainage ditches, and check them frequently during the rainy
season. This task is a community responsibility.
+ Test all drainage ditches for functioning outlet drains. This should be tested with a hose and done
before the rainy season. All blockages should be removed.
+ Check all drains at top of slopes to be sure they are clear and that water will not overflow the slope
itself, causing erosion.
+ Keep subsurface drain openings (weep-holes) clear of debris and other material which could block
them in a storm.
+ Check far loose fill above and below your property if you live on a slope or terrace.
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Monitor hoses and sprinklers. During the rainy season, little, if any, irrigation is required.
Oversaturation of the ground is unnecessary, increases watering costs, and can cause subsurface drainage.
Watch for water backup of drains inside the house and toilets during the rainy season, as this may
indicate drain or sewer blockage.
+ Never block terrace drains and brow ditches on slopes or at the tops of cut or fill slopes. These are
designed to carry away runoff to a place where it can be safely distributed.
Maintain the ground surface upslope of lined ditches to ensure that surface water is collected in the
ditch and is not permitted to be trapped behind or under the lining.
•• Do not permit water to collect or pond on your home site. Water gathering here will tend to either
seep into the ground (loosening or expanding fill or natural ground), or will overflow into the slope and begin
erosion. Once erosion is started, it is difficult to control and severe damage may result rather quickly.
+ Never connect roof drains, gutters, or down spouts to subsurface drains. Rather, arrange them so that
water either flows off your property in a specially designed pipe or flows out into a paved driveway or street.
The water then may be dissipated over a wide surface or, preferably, may be carried away in a paved gutter or
storm drain. Subdrains are constructed to take care of ordinary subsurface water and cannot handle the
overload from roofs during a heavy rain.
+ Never permit water to spill over slopes, even where this may seem to be a good way to prevent ponding.
This tends to cause erosion and, in the case of fill slopes, can eat away carefully designed and constructed
sites.
Do not cast loose soil or debris over slopes. Loose soil soaks up water more readily than compacted
fill. It is not compacted to the same strength as the slope itself and will tend to slide when laden with water;
this may even affect the soil beneath the loose soil. The sliding may clog terrace drains below or may cause
additional damage in weakening the slope. If you live below a slope, try to be sure that loose fill is not
dumped above your property.
Never discharge water into subsurface blanket drains close to slopes. Trench drains are sometimes
used to get rid of excess water when other means of disposing of water are not readily available. Overloading
these drains saturates the ground and, if located close to slopes, may cause slope failure in their vicinity.
Do not discharge surface water into septic tanks or leaching fields. Not only are septic tanks
constructed for a different purpose, but they will tend, because of their construction, to naturally accumulate
additional water from the ground during a heavy rain. Overloading them artificially during the rainy season is
bad for the same reason as subsurface subdrains, and is doubly dangerous since their overflow can pose a
serious health hazard. In many areas, the use of septic tanks should be discontinued as soon as sewers are
made available.
+ Practice responsible irrigation practices and do not over-irrigate slopes. Naturally, ground cover of ice
plant and other vegetation will require some moisture during the hot summer months, but during the wet
season, irrigation can cause ice plant and other heavy ground cover to pull loose. This not only destroys the
cover, but also starts serious erosion. In some areas, ice plant and other heavy cover can cause surface
sloughing when saturated due to the increase in weight and weakening of the near-surface soil. Planted slopes
should be planned where possible to acquire sufficient moisture when it rains.
+ Do not let water gather against foundations, retaining walls, and basement walls. These walls are built
to withstand the ordinary moisture in the ground and are, where necessary, accompanied by subdrains to carry
off the excess. If water is permitted to pond against them, it may seep through the wall, causing dampness and
leakage inside the basement. Further, it may cause the foundation to swell up, or the water pressure could
cause structural damage to walls.
Do not try to compact soil behind walls or in trenches by flooding with water. Not only is flooding
the least efficient way of compacting fine-grained soil, but it could damage the wall foundation or saturate the
subsoil.
. Never leave a hose and sprinkler running on or near a slope, particularly during the rainy season. This
will enhance ground saturation which may cause damage.
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+ Never block ditches which have been graded around your house or the lot pad. These shallow ditches
have been put there for the purpose of quickly removing water toward the driveway, street or other positive
I .outlet. By all means, do not let water become ponded above slopes by blocked ditches.
Seeding and planting of the slopes should be planned to. achieve, as rapidly as possible, a well-
establishedand deep-rooted vegetal cover requiring minimal watering.
I + It should be the responsibility of the landscape architect to .provide such plants initially and of the
residents to maintain such planting; Alteration of such a planting scheme is at the resident's risk.
I + The resident is responsible for proper irrigation and for maintenance and repair of properly installed
irrigation systems. Leaks should be fixed immediately. Residents must undertake a program to eliminate
burrowing animals. This must be an ongoing program in order to promote slope stability. The burrowing
animal control program should be conducted by a licensed exterminator and/or landscape professional with I expertise in hill side maintenance.
Geotechnical Review
Due to the fact that soil types may vary with depth, it is recommended that plans for the construction of rear
yard improvements (swimming pools, spas, barbecue pits, patios, etc.), be reviewed by a geotechnical
engineer who is familiar with local conditions and the current standard of practice in the vicinity of your
home.
In conclusion, your neighbor's slope, above or below your property, is as important to you as the slope that is
within your property lines. For this reason, it is desirable to develop a cooperative attitude regarding hillside
maintenance, and we recommend developing a "good neighbor" policy. Should conditions develop off your
property, which are undesirable from indications given above, necessary action should be taken by you to
insure that prompt remedial measures are taken. Landscaping of your property is important to enhance slope
and foundation stability and to prevent erosion of the near surface soils. In addition, landscape improvements
I should provide for efficient drainage to a controlled discharge location downhill of residential improvements
and soil slopes.
Additionally, recommendations contained in the Geotechnical Engineering Study report apply to all future
1 residential site improvements, and we advise that you include consultation with a qualified professional in
planning, design, and construction of any improvements. Such improvements include patios, swimming
pools, decks, etc., as well as building structures and all changes in the site configuration requiring earth cut or I fill construction.
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October 15, 2010 SUMMARY OF LABORATORY Page 1 of Table 1
P1W 1004-02
. MAXIMUM DRY DENSITY AND Report No. 1004-02-C-4
OPTIMUM MOISTURE CONTENT
TABLE 1
. .
. OPTIMUM MAXIMUM
MOISTURE • DRY
CONTENT DENSITY
SOIL TYPE
•
DESCRIPTION • (%) (pcf)
A • Light Brown Silty to Clayey Sand 13.9 118.0
(
Copy of 1004-02-C-4 Compaction Test Table Final/Max Table
ADVANCED GEOTECHNICAL. SOLUTIONS, INC.
U.. U — .•- — — — - —. — — —. —. — — — — — —
OctOber 15, 2010 FIELD DENSITY TEST RESULTS Page 2 of Table 1
P/W10O4002 - - - ---• - --- - -- -TABLE-i- (cont'd) -•------- --• --- -
—Report No.-100402C-4 —
TEST NUMBER/LOCATION/ELEVATION KEY
S - Sewer Trench I - Irrigation Trench SD - Storm Drain Trench E - Electrical Trench ii - Joint Utility Trench W - Water Trench RTW - Retaining Wall FTG - Footing FG - Finish Grade
SG - Subgrade CG - Curb and Gutter Subgrade B - Base AC - Asphalt Concrete Finish Grade BC - Asphalt Concrete Base Course CC - Asphalt Concrete Cap Course -R,R1,R2 - indicates Retest
* Rock Correction- Estimated Percent Retained on #4 Sieve (Method A) or 3/4 inch (Method C), Maximum Dry Density and Optimum Moisture Content adjusted per ASTM D 471
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Number
Depth
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Moisture Dry Density Rel.
I comp.. I -
Pass
Building Pad
Building Pad
Building Pad
Copy of 1004-02-C-4 Compaction Test Table Final/Tests ADVANCED GEOTECIINICAL SOLUTIONS, INC.