BRES2020-0155 - Geotechnical ReportSladden Engineering
45090 Golf Center Parkway, Suite F, Indio, CA 92201(760) 863-0713
6782 Stanton Avenue, Suite C, Buena Park, CA 90621 (714) 523-0952
450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743
www.Sladdenengineering.com
May 28, 2020 Project No. 544-20168
20-05-293
Discovery Builders California, Inc.
BRES2020-0155
53965 Humboldt Boulevard
CITY OF.LA QUINTA
La Quinta, California 92253
NI
BUIR VIEW DDIVIOSRON
CODE
COMPLIANCE
Subject: Geotechnical Update =X1012812020 n
Project: Proposed Custom Residence 15,909SF S.F.D.
53335 Ross Avenue
The Madison Club Lot 30A
La Quinta, California
Ref: Geotechnical Investigation Report prepared by Sladden Engineering dated January
28, 2005; Project No. 544-4810, Report No. 05-01-101
Report of Testing and Observation During Rough Grading prepared by Sladden
Engineering dated March 2, 2006; Project No. 522-4810; Report No. 06-02-120
In accordance with your request, we have reviewed the above referenced geotechnical reports as
they relate to the design and construction of the proposed custom residence to be constructed on
Lot 30A located at 53335 Ross Avenue within the Madison 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 referenced reports include recommendations pertaining to the design and construction of
residential structure foundations. The previous reports also address the potential for
liquefaction, subsidence and differential settlement. 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.
The allowable bearing pressures recommended in the referenced Geotechnical Investigation
report remain applicable. 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 1500 psf and 2000 psf, respectively. Allowable increases of 300 psf
for each additional 1 foot of width and 300 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.
Sladden Engineering
May 28, 2020 -2- Project No. 544-20168
20-05-293
Lateral forces may be resisted by friction along the base of the foundations and passive resistance
along the sides of the footings. A friction coefficient of 0.48 times the normal dead load forces is
recommended for use in design. Passive resistance may be estimated using an equivalent fluid
weight of 300 pcf. If used in combination with the passive resistance, the frictional resistance
should be reduced by one third to 0.33 times the normal dead load forces.
The bearing soil is generally non -expansive and falls within the "very loud' expansion category in
accordance with the 2019 (CBC) classification criteria. Slab thickness and reinforcement should
be determined by the Project Structural Engineer. We recommend a minimum floor slab
thickness of 4.0 inches and minimum reinforcement of #3 bars at 24 inches on center in both
directions. All slab reinforcement should be supported on concrete chairs to ensure that
reinforcement is placed at slab mid -height.
Slabs with moisture sensitive surfaces should be underlain with a moisture vapor retarder
consisting of a polyvinyl chloride membrane such as 10-mil visqueen, or equivalent. All laps
within the membrane should be sealed and at least 2 inches of clean sand should be placed over
the membrane to promote uniform curing of the concrete. To reduce the potential for punctures,
the membrane should be placed on a pad surface that has been graded smooth without any sharp
protrusions. If a smooth surface cannot be achieved by grading, consideration should be given to
placing a 1-inch thick leveling course of sand across the pad surface prior to placement of the
membrane.
The seismic design category for a structure may be determined in accordance with Section 1613
of the 2019 CBC or ASCE7-16. According to the 2019 CBC, Site Class D may be used to estimate
design seismic loading for the proposed structures. The 2019 CBC Site Specific Seismic Hazard
Analyses are attached.
The subject lot was previously graded during the rough grading of the Madison Club project site.
The rough grading included over -excavation and re -compaction 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 report of Testing and Observation During Rough Grading along
with the compaction test results.
Because the lot has been previously rough graded, the remedial grading required at this time
should be minimal provided that the building area falls within the previously assumed building
envelope. The building areas should be cleared of surface vegetation, scarified and moisture
conditioned prior to precise grading. The exposed surface should be compacted to a minimum of
90 percent relative compaction prior to fill placement. The previously removed soil and any fill
material should be placed in thin lifts at near optimum moisture content and compacted to at
least 90 percent relative compaction.
Sladden Engineering
May 28, 2020 -3- Project No. 544-20168
20-05-293
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,
SLADDEN ENGINEERING
Brett L. Amer on j BRA► L. \�`2
y�j� ANDERSON
Principal Engineer CD No. C4s389 ?
ENGINEERING *.
SER/ra
Copies: 4/ Discovery Builders California, Inc.
Sladden Engineering
�,-N )x w'
Please verify that soils reports contain all of the above information. In addition, to assure
continuity between the Investigationlreporting stage and the execution stage, please use
the following checklist to verify that the conclusions and recommendations in the report
cover all the required elements. Only then can we be assured that the construction
documents address all of the site soli conditions.
!_a Quinta Geotechnical Report Checklist
Does the "Conclusions and Recommendations" section of the report address each of the
following criteria?
"Address" means;
(a) the criterion Is considered significant and mitigation measure(s) noted, or;
(b) the criterion is considered Insighificant and explicitly so stated.
Y 'No
Cr`lterion
❑
Foundation criteria based upon bearing capacity of natural or compacted soil.
R
Foundation criteria to mitigate the effects of expansive soils.
C�
❑
Foundation criteria based upon bearing capacity. of natural or compacted soil.
❑
Foundation criteria to mitigate.the effects of liquefaction.
❑
Foundation criteria to mitigate the effects of seismically induced differential
settlement.
1
C
❑
Foundation criteria to mitigate the effects of long-term differential settlement
Ld"
❑
Foundation criteria to mitigate the effects of varying soil strength.
!f
❑
Foundation criteria to mitigate expected total and differential settlement.
Any "No"
answers to the above checklist should be noted as specific required
corrections.
Ww
h
oN'V
o
0
amo
0 0
o o m m
u` m m
m m om w w
j
.-�
o
.-i
.-+
o
`i
o
0
0
0
0 0
0 0 0 0 0
®
a
o o 0
0 0 0 0 o
Q
Q
a
4
0 0
0 0 0 w o
u
✓1
vi
vl
0U
U
N M
d' N t0 t0 O
0 0
0 0 0 0 c-I
Z
W
E
Yam,
4 w
1O
o
C
LL
\
N
n
M
0 0
W D
Q
Q
Q
N
LL
Q
Q
C
V
N
w
N
N
N
N
N N
I
win
C
C
C
LL
b0
M
a-1
t0
N
O
m
m
O
O
O
O
O
O
F
C
N
O
O
O C
N
O
V1
C
m
�
d
ei
W
D
Q
v
W
W
O
U 3
m
N
LL
a m
m ro
0 0
U u
0
ti
W
a
In
U_
U1
J
m
Q
m
O
it
a
a
C
a
"6
a
a
0
WU
t
m
a
Ln
e
r4
N
U
w
r to m
m co n N o v W + N m N m m h W W m tD sr
u
n CO N n N 0) K m 4 to to MN M n v .- �r M 1 00 dr -4o
2
w W M of to %D W W n t0 U) '�T N 14 t` LA cT ,
O O O O =-i -1 �i , 4 r-1 H s-i r•-i .4 r-i .4 r-i r4 ri t 4
0
a
G1
lJ
lD tD lD lD tD tD O lD tD tD tD tD V [V O O0 tD m m m 0) 01 Ql
~'
0 0 0 0 0 0 0 0 0 0 0 0 0 0 n C1 m m m M m W 00
41) u
Ol 0) m m Ql m 0) m m m m m 0) m Cl 00 W w 00 W 00 W 00
O
U
O O O O O O O O O O O O O O O O O O O O O O O
Y
K
I=
Q H CO m tD n 00 a) a) VM M n tD N V C! 00 111 N M W r,
Io
tD 00 N n N O n W to H N N H N M H 'd' Ol N 00 H W 00
0) C) O O ri N M d' to n W O O Cl W n W M N 00 ID Ch M
c0)
G
o 0 H r-1 H .-4 H r-1 ra H H N N H. 4 r-1 r-1 H H 0 0 0 O
- tTI rrl U'1 n M r` tO n 0) 0) Q' O •-1 'T O C m n m TT tr H
-
tD H lD M --r M 0) C) W O W W tD M U1 lD Ul 0) 1� QI M N
7 rti .-1 N M r3' trl 10 W O -i r•1 O t0 t` tD -t N CO 11 1l r»
U
.4 .-t r.1 .4 .-I .-+ H N ry N N 11 rl r1 H li O O O O
M
N 00 n rsl O V U) N 00 U) CO O N 00 t0 O 01 n (y) n Cl t- t-
00 o0 N O m m m m tD m m m (Ij -4 tD OO N tO �r m U1 Cl Ir
Di 00 rn O O H N rA ^7 t11 1p 00 00 n 1D U) U1 M N Ol l0 U) 7
�-�
0 0 0 H H H -1 ,-1 H r-1 H H .-i H .-1 ,-1 rl H H O (D O O
C) 00 U1 n N 0) CO (n 0) 0) 00 M ID 00 W to H Q r-i M Ul 01
r`-(N
V' 0) m n U) fJ r-1 M M rT M n Ul ry Cl m lD N m m b' h
0) 01 01 O O H M V Q 10 n Ol M 0) Ol 00 n M rV ao M V' n-,
r-1 H H H --1 .-1 r1 r-1 H r4 .--4 H .--1 O (D O C
U) O O O O O O O O O tD O O O O O O O O O O O O
O
O N M cr U) tD o0 0) O N M O O O O O CO 0 0 0 n C) Cl
O O O O O O O O H H I-1 N M ^J• U1 lD tD O N 0 0 0 0
a
O O O O O O O O O O O O O O O O O H -I N m 7 U)
m
n O
W Z
6
u
u
o u
o cr
W N li
OW
N O
V) Q to
=3 Z U)
Q 7
U O Q
7 O l7
� N Z
o n
O O
O
= O N
C WO h0
Y ' 7
Q 0
v a �
o E .o
O to L
m u u
Q L1 }
N 6 0
c
0
m
3
a
W
c
O
:i.
10
7
C
07
r+
a
0
0
c
(0
U1
'O
N
r
DO
aj
m
C
N �
U Q
W r
LL u to
In m N
u U c
y� L
� u �
Z 0 00
H In
� Q u
W to a.
0
Q In
�+ c
c _
0
u
C c
O O
p u
O
c
a
O
C9
w
O
N
7
a
e
a
W
-7 co (-I O 00 d' ('� m " tD ,-i lD 00 O Ln 1 N ti7 CDv-1 F`
'71 O 4 00 r1 R 00 m m w In zT -I N j' f11 rV " 1'4 cr f.1 w -
7 r r- tr Do 00 iT O O H N ro V V m N a, n 0
O O O 0 6 -4 .-i ,-i -4 r4 14 .i . t rc .-i i -4 O O O
� cO N o CO m m N tO �1 k.0 CO o Ln !i .-1 N to : , . ,
m o w 4 n w m m w Ln � r-+ N d* m N �-+ N cr iO d•
tD rl� r-� r` o0 M M o o r•1 N cn lzY e: d; -; cr m " m r, vi 1;
0 0 0 O O 0 O�l r•i .-t e l .-i -i ri 11 r4 1-4 . q .-4 0 0 0 O
Ln 0 0 0 0 0 0 0 0 0 to 0 0 0 0 0 0 0 0 0 0 0 OI
O N m V' Ln lD 00 m O N m 0 0 0 0 0 00 O O O O O O
0 0 0 0 0 0 0 0 1-1 14 .-1 (V m cr in tD tD O N 0 0 0 0
O O O O O U 6 0 0 0 0 0 0 0 0 0 0 I-i 14 N Or; d ui
m W
6 1-
0
z
r•
cv
w
N
V
X
E
In
O
m
V
oc
u o0
Of o U
o cc
O (D CO
(V In 0
Ln O
U Q to
� l7 C7
Z D
Ln u 00
z o 0
c ry z
oo•@:3 tin
c
w O o
c V) m o
0 Y �
41 _ O
co >•
D Q O1
L Q :3
L
»� O E .0
Q O m t
f m U u
co
to
0
0
th
0
Z
W
O
2912
I
-- '--
--�—
! I
i
1 ,
I
i I
LM
W
N V1
- -i
-� ---I
----
W Wui
- I -�-'--
- -I- -
I--'--
'--
I—
+ -
a
H
I
i
Hit I
1
1
,
�
R
H
U
w
a
U
LL.
U
w
a
in
W
H
Q,
ul V
w
m
w rh -4 w �-t in .-i O
O O O O O O O O
O O O m
r- d 1n N r
to m
W
rn
- w N
to
m
N m M tD O m m 0
0 0 0 0 o o 0
0 0 0 to
.-1 m 1n tD n
w m .4
rn �7
v
v
rn 1n tD tD r- r` r O0
00 00 00 00 00 00 00 00
00 00 00 to
tD 1_n in c� ry
14 .-4 -t
(U
o O
O
O
O O O o 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0
o d O Q 0
0 0 CJ
O
O
CO
OJ
lD
zp
v
N In
O
rn
to o w
m
m to
m w
O
O
o
0
pp
o
0
0
0
00
0 w
1-1
CD 1* w
rl-
'A
r+m m
N
N w
m
1,
H lD It
m r,
r1 m
0
0
0
0
0
0
0
0
0
0
0 0 .-I
r-
M m r-
d
m
r- M
f-
d' a'
rn
rn
rD t0 r,
n
00 00
m m
0
0
0
0
0
0
0
0
0
0
c7 O W
rl
t- lD M
M
U
w
1O
0 0
0
0
0 0 0
0
0 0
0 0
-i
H'
4
i
. 4
H
�I
-1
4
c-1
v
c
w
d
Ln
Q
M O O
O
O O O O
O O
O tD
O
O
O
O
O
O
O
O
O
O
O O O
O
O O O
O
O
O O
O
O N
M
ct
1n lD 00
m
0 r1
N M
1n
lD
n
CO
m
0
0
0
0
0
d' CO rn
O
Ul O O
O
O
O O
O
O
O O O
O
H
'1
r-!
-4
-4
'-!
-4
N
M
d
to
lD
lD lD 00
m
m O cV
0 0
O O
O
O
O O O
O
O O
O O
O
O
O
O
O
O
O
O
O
O
o 6 6
6
6 .-1 --1
N
m
4 1n
ti
c 1n
o
Q E
N
N
N
ct
w
h
m
Q
w Ln
m m
rdn m
��} Q tmp
�
Ln sA
Q
N w
c-
n
- d
�7
in
VI
U1 tp
tp h r-.
co 00
Cfl m
m Ol
00
r`
rn m
rJ
O
[7
O
Q
a
O O
O O O
O O
O O O
O O
O
O
O O
O
aO ar
vi a
O1 to
O
u
'1-
u
d w
N
O
w
d m
m N w
.-1 w
w O rn
.-1 '-1
m
tD
d M
d
w
d
(Ti O
d
00
H
rl00
m m 00
in It
c-a N d'
m 1V
^.t
c-+
00 V
•-1
'ct
LA u
l0 r
(`
n
CO
00 071
O O ci
rV M
d d d
at d
N
v--1
r`• Ln
`f
m
O O
O
O
O
O O
-1 H eA
%-1 "
r-I e-4 -1
.-1 .--1
r-1
4
0 0
0
0
41
.-
Ln
Y
00
N
O
CO
^ in
ryl N 00
O
c7 O
r-1 rI
rJ
in
O *'1
r,O
d
CO
r-1
r- 00
m 00
rn 7
A
-+ rJ -T -t
rn N
rV
0 M
lD
.r r•.
h•
(�
00
:A J1
a U -4
N r-1
-4d' d
d -7
M rn
N
m h
Ln
o
o
(D
O
o o
^i .4 --i
.4 14
-4 -i .4
-4 ri
14
14
O
N
O/
O
U
w
nl 00
rl
N
O
d w
1-1 N m
N m
m r\ w
w m
rn
to
d in
't
d
U
r` 00
N
r�
N
m d
m eH m
Ln M
N m V'
m r-
d
.-1
00 It
--Id
16
4J 00
Ol
cn
O
O N
rn d; in
LD 00
co r, w
Ln �t
N
-i
r- to
-i
m
-
o
a`
rn O
O
O
O
O O
O O O
tD O
O O O
O O
O
O
O O
O
o
O
o N
m
d
rn
lD M
m O N
M 0
0 0 0
0 W
o
0
0 0
0
0
M d' Lq
lfl tD
O
N
O O
O
O
y
CL
0 0
0
0
0
0 0
0 0 0
0 0
0 0 CD
0 0
.-1
.-i
N rn
cr
in
d m N
r-
r-
-i
O
d
N
7
(O
lD
00
ct
-,
O
M
N
n
m
lD
C O
>
o
-1
,-1
.-i
O
O
N
u
N
n
�r
vr
C
f`
10
O
rq
m
()
f0
OR
li
rn
r�
lD
'n
Q
>
o
ri
.-i
-i
o
U
O
tA
�
10
in
m
m
to
a u
u �
'u in
v
CL
rn
N
.w
in
,.
�Iffi
ate.
v O
U U
nco co
C 1 N tD
O O w
Cu_ Cu_ v
C G Y
4A t
Z 'Fu Of
rn to *
E
u
I
a
a
`
E
2 !
I
E
�
c
�
u
a
a
ui
� U
w
U
U
W
A
�
�
d
. i
'C"�
c
p
o.
in
N
CL
C
INn
O
y
c
m
O
y
L
n
w
Ol
0
J.S. Seismic Design Maps
https://seismicmaps.org-
Ross Avenue
Latitude, Longitude: 33.661179,-116.247975
The Madison Club
OSHPD
Date
5126/2020, 3:58:39 PM
Design Code Reference Document
ASCE7-16
Risk Category
II
Site Class
D - Stiff Soil
Type
Value
Description
SS
1.5
W;ER ground motion. (for 0.2 second period)
S1
0.612
MCER ground motion. (for 1.Os period)
Sms
1.5
Site -modified spectral acceleration value
Sim
null -See Section 11.4.8
Site -modified spectral acceleration value
SDS
1
Numeric seismic design value at 0.2 second SA
Sol
null -See Section 11.4.8
Numeric seismic design value at 1.0 second SA
Type
Value
Description
SDC
null -See Section 11.4.8
Seismic design category
Fa
1
Site amplification factor at 0.2 second
Fv
null -See Section 11.4.8
Site amplification factor at 1.0 second
PGA
0.656
MCEG peak ground acceleration
FPGA
1.1
Site amplification factor at PGA
PGANI
0.722
Site modified peak ground acceleration
11L
8
Long -period transition period in seconds
SsRT
1.784
Probabilistic risk -targeted ground motion. (0.2. second)
SsUH
1.969
Factored uniform -hazard (2% probability of exceedance In 50 years) spectral acceleration
SsD
1.5
Factored deterministic acceleration value. (0.2 second)
S1 RT
0.692
Probabilistic risk -targeted ground motion. (1.0 second)
S1 UH
0.778
Factored uniform -hazard (2% probability of exceedance in 50 years) spectral acceleration.
SID
0.612
Factored deterministic acceleration value. (1.0 second)
PGAd
0.656
Factored deterministic acceleration value. (Peak Ground Acceleration)
CRs
0.906
Mapped value of the risk coefficient at short periods
Wp data ((i)2020
I of 3
5/26/2020, 3:59 PM
J.S. Seismic Design Maps https://seisinicmaps.orW
Type Value Description
Cqt 0.889 Napped value of the risk coefficient at a period of 1 s
of 3 5/26/2020.3:59 PM
J.S. Seismic Design Maps https://scismicmaps.org/
DISCLAIMER
While the information presented on this website is believed to be correct, SEAOC /OSHPD and its sponsors and contributors assume no responsibility or
liability for its accuracy. The material presented in this web application should not be used or relied upon for any specific application without competent examination
and verification of its accuracy, suitability and applicability by engineers or other licensed professionals. SEAOC / OSHPD do not intend that the use of this
information replace the sound judgment of such competent professionals, having experience and knowledge in the field of practice, nor to substitute for the
standard of care required of such professionals in interpreting and applying the results of the seismic data provided by this website. Users of the information from
this website assume all liability arising from such use. Use of the output of this website does not imply approval by the governing building code bodies responsible
for building code approval and interpretation for the building site described by latitudellongitude location in the search results of this website.
3 of 3 5/26/2020, 3:59 PM