BRES2015-0352 Geotechnical Updatev
Sladden Engineering
45090 Golf Center Parkway, Suite F, Indio, CA 92201 (760) 863-0713 Fax (760) 863-0847
6782 Stanton Avenue, Suite C, Buena Park, CA 90621 (714) 523-0952 Fax (714) 523-1369
450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863
800 E. Florida Avenue, Hemet, CA. 92543 (951) 766-8777 Fax (951) 766-8778
October 23, 2015 Project No. 544-15280
15-10-448
Sun Vista Development Corporation
P.O. Box 1144
La Quinta, California 92247woo
Subject: Geotechnical Update_
Project: Custom Residence
52-560 Del Gato Drive — Lot 4 ��(`i 01
Tradition Golf Club OMMVN1
La Quinta, California G
Ref: Report of Testing and Observation During Rough Grading prepared by Sladden
Engineering dated July 30, 1997, Project No. 522-6138G1
Geotechnical Update report prepared by Sladden Engineering dated December 12,
1996; Project No. 444-6130
As requested, we have reviewed the referenced geotechnical reports as they relate to the design
and construction of the proposed custom residence. The project site is located at 52-560 Del Gato
Drive (identified as Lot 4) within The Tradition Golf Club development in the City of La Quinta,
California. It is our understanding that the proposed residential structure will be of relatively
lightweight wood -frame construction and will be supported by conventional shallow spread
footings and concrete slabs on grade.
The lot was previously graded during the initial rough grading of the Tradition Golf Club project
site. The rough grading included over excavation and/or recompaction of the native surface soil
along with the placement of engineered fill material to construct, the building pads. The site
grading is summarized in the referenced grading report along with the compaction test results.
The referenced reports include recommendations pertaining to the design and construction of
residential structure foundations. Based upon our review of the referenced reports, it is our
opinion that the structural values included in these reports remain applicable for the design and
construction of the proposed residential structure foundations.
3
October 23, 2015 . -2- Project No. 544-15280
15-10-448
Conventional shallow spread footings should be bottomed into properly compacted fill material
a minimum of 12 inches below lowest adjacent grade. Continuous footings should be at least 12
inches wide and isolated pad footings should be at least 2 feet wide. Continuous footings and
isolated pad footings should be designed utilizing allowable bearing pressures of 1800 psf and
2000 psf, respectively. Allowable increase of 200 psf for each additional 1 foot of width and 250
psf for each additional 6 inches of depth may be utilized, if desired. The maximum allowable
bearing pressure should be 3000 psf. The recommended allowable bearing pressures may be
increased by one-third for wind and seismic loading. Increases in allowable bearing pressures
may be realized with increased footing size.
Resistance to lateral loads can be provided by a combination of friction acting at the base of the
slabs or foundations and passive earth pressure along the sides of the foundations. A coefficient
of friction of 0.48 between soil and concrete may be used with dead load forces only. A passive
earth pressure of 300 pounds per square foot, per foot of depth, may be used for the sides of
footings, which are placed against properly compacted native soils.
The bearing soil is non -expansive and falls within the "very low" expansion category in
accordance with 2013 California Building Code (CBC) classification criteria. Slab thickness and
reinforcement should be determined by the structural engineer, we recommend a minimum floor
slab thickness of 4.0 inches. All slab reinforcement should be supported on concrete chairs to
ensure that reinforcement is placed at slab mid -height.
Because the lot has been previously graded, the remedial grading required at this time for the
proposed residence should be minimal. The building areas should be cleared of surface
vegetation, scarified and moisture conditioned prior to precise grading. The exposed surface
should be compacted so that a minimum of 90 percent relative compaction is attained prior to fill
placement. Any fill material should be placed in thin lifts at near optimum moisture content and
compacted to at least 90 percent relative compaction.
Based on our field observations and understanding of local geologic conditions, the soil profile
type judged applicable to this site is So, generally described as stiff soil. The following presents
additional coefficients and factors relevant to seismic mitigation for new construction based upon
the 2013 California Building Code (CBC).
The seismic design category for a structure may be determined in accordance with Section 1613
of the 2013 CBC or ASCET According to the 2013 CBC, Site Class D may be used to estimate
design seismic loading for the proposed structures. The 2013 CBC Seismic Design Parameters are
summarized on the following page.
Sladden Engineering
October 23, 2015
-3-
Project No. 544-15280
15-10=448
Risk Category (Table 1.5-1): I/U/III
Site Class (Table 1613.3.2): D
Ss (Figure 1613.3.1):1.500g
S1 (Figure 1613.3.1): 0:609g
Fa (Table 1613.3.3(1)):1.0 .
Fv (Table 1613.5.3(2)):1.5
Sms (Equation 16-37 (Fa X Ss)): 1.500g
Smi (Equation 16-38 (Fv X Si)): 0.9148
SDS (Equation 16-39 (2/3 X Sm5)):1.000g
SD1(Equation 16-40 (2/3-X Sml)): 0.609g
Seismic Design Category: D
In addition, we have sampled the surface soil on the subject lots to determine the soluble sulfate
content as it relates to selecting appropriate concrete mix designs. Testing indicates that the site
soil is generally considered non- corrosive with respect to concrete. The testing indicated soluble
sulfate content of 600 ppm (0.060 percent) that corresponds with the "negligible" exposure
category in accordance with ACI 318-08, Table 3. Based upon this, the use of sulfate resistance
concrete mixes should not be required.
We appreciate the opportunity to provide service to you on this project, if you have any
questions regarding this letter or the referenced reports please contact the undersigned.
Respectfully submitted,
SL.ADDEN ENGINEERINGaOFESS/n. _
BRETT L.
rj ANDERSON Z
No. C45389 m
Brett L. Anderson W p• 9/30/16
CIVIL
Principal Engineer ik ENGINEERING
tp
Letter/clb OF CAS-�F��
Copies: 4/ Sun Vista Development Corporation
Sladden Engineering
Please verify that soils reports contain all of the above Information. in addition, to assure
continuity between the Investigation/reporting stage and the execution stage, please use
the following checklist to verify that the conclusions and recommendations in the report
cover all the required Blements. Only then can we be,assured that the construction
documents address al of the site soil conditions.
La Quinta Geotechnical Report Checklist
Does the °Conclusions and Recommendations° section of the report address each of the
following criteria?
"Address" M' MIS:
(a) the criterion Is considered significant and mitigation measures) noted, -or,
(b) the criterion is considered insightficant and explicitly so stated.
Yes . No Criterion
i Cl Foundation criteria based upon bearing capacity of natural or compacted soil.
❑ Foundation criteria to mitigate the effects of expansive soils.
❑ Foundation ,criteria based upon bearing capacity. of natural or compacted soil.
❑ Foundation kriteria to mitigate.the effects of liquefaction.
❑ Foundation criteria. to' mitigate the effects of seismically. Induced differential
settlement.
❑ Foundation arteria to mitigate the effects of long-term differential settlement.
❑ Foundation criteria to mitigate the effects of varying soil strength_
❑ Foundation criteria to mitigate expected total and differential settlement.
Any "No" answers to the -above checklist should be noted as specific required
con'ections.
Sladden Engineering
6.782 Stanton Ave., Suite A, Buena Park, CA 90621 (714) 523-0952 Fax (714) 523-1369
45090 Golf Center Pkwy, Suite F, Indio, CA 92201. (760) 863-0713 Fax (760) 863-0847
450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863
Date: October•28, 2015
Account No.: 544-15280
Customer: Sun Vista Development Corporation
Location: Traditions CC, Lot 4, 52-560 Del Gato, La Quinta
Analytical Report
Sulfate Series
Soluble Sulfates Soluble Chloride
per CA 417 per CA.422
PPM PPM
600 300
Ri dfala .rd& -i r.9Rn 1 n9R IR
r.
TAQLE 19=A•2-REQUIREMENTS FOR SPECIAL EXPOSURE CONDITIONS'
" , - -• hTINIMUMl�,
MAXIMUM • MOR D .
WATER:MAE MIOUS :
UG� EIGHT
MATERmLS' RA1TO; BY.: AGGRECiATEgORCAE]
EXPO5UAErONDt[TON •WEIGHT.�NbRMAC-WEIGHT•
SUREAGGbEGATE CONCRETE • '
intended to haveh3wpermeability when
x p.l)p689•lor MD-
exposed to water
4,000
Conerele exposed to'freezing and tiaawing in a moist
condition or to deicing chenucgls 0.45
For corrpsion projection for�tinforeed concrete
4500
exposed to chlorides from deicing Chemicals, salts or
brackish:water. oespray-front thtsc'sotuces
. 0.40
5,000
TABLE 19-A-3—REQUIREMENTS;FOIJCONC13ETE
- OrPOSED TO SULFATE-c09TA1NING•SOLtUT10NS
NORMAL-WEIGHT1.
AGGEGATE
AGOREG7►TE
. CONCRETE
Madmuin vlatar•
WATER-SOLUBLE Cbmenthrous
f" 'Normal-
•talphtand
SULFATE MdtarisWRetlo,-by:.
( t, Sqt' wdght,
SULFATE PERCEMAGIE Naimol W�Igtit
=,Uphtw61pht'
' -Aaaftata, .
Concrilbe
BY SULFATE (SO4) tN
EXPOSURE W1IGH'r„ WATER, Ppm CEMEFTTYPE
pilf
Concrete)
x01*6H9Tor6tPa
Negligible D.00L0.IC 0-150
• Modecatc2_ 0.1D-0.2C 150-1,500 II, ]P(MS). is '050-
4,000
Seven 0.20-2.0U 45D0-110.000 V 0.45r
¢,500
Very seven Over20p Over 10,000 V plus 0.45
4500 .
• , poaolanz
_ _
to lower water-ccmzntidotu maxrials ratio orhigherstrm may be rrcluired for Inw pergcibilky�orforpmection '
gth against eotrosion'of cmbMdcj items or frecsin
and
$cawatcr_ g wing ('fables 19=A-2). .
?Fnz lan that has been dttcrmir-d by test or service tceotd to improve sulfate trsistan� when in
bdsiing TFJ= V ccmrnL turd
concrete cors-
2-264