HomeMy WebLinkAboutCT 72-20; La Costa Vale Unit 1; Soils Report Preliminary; 1971-10-22PHlLlP HENKING BENTON
PI1EsIoE*, ClYlL LNGlNEEI
BENTON ENGINEERING. INC.
APPLIED 501L MECHANICS -~~ FOUNDATIONS
674, El. CAJDN BOULEVARD *AN DIE00. CALIFORNIA s*,15
October 22, 1971
CT ‘7 2-m
SAN DIc.50: S83.5654
LA MESA: 469.5654
Rancha La Costa
Route 1, Box 2550
Encinitas, California 92024
Subject: Pro/ect No. 71-10-W
Preliminary Soils Investigation
La Costa Vale No. 1
~3s-ao dw'tl
Northwest of the in?ersection of
La Costa Avenue and
- Ran&o Santa Fe Road
Lo Costa Area, San Diego County, California
Gentlemen:
CONCLUSIONS
it is concluded from the field investigation and laboratory test results that:
- 1. The medium firm to very firm natural soils are suitable for support of the pra-
posed fills and/or msidential structures. However, loose or porous compressible upper soils,
similar to those encountered to a depth of 6.5 feet in goring 2-11, and to 6.0 feet In goring - la-iv, may be expected to exist in certain low areas. It is recommended that these
materials, and similar materials be removed, and that the compacted filled ground and/or
Footings be placed on the underlying natural soils determined suitable For Foundation support. - Also potentially expansive clayey fine sand, sandy clay, silty clay, and clay soils were Found
in certain amas and specially designed footings and slabs are recommended where these ex-
pansive soils are allowed to remain in place within the upper 3 Feet below finished grade. -
2. It is concluded From the results of the laboratory tests that the natural soils,
suitable for structural support, have a safe bearing capacity of at least 2500 pounds per - square Foot For one Foot wide continuous footings placed at least one Foot below Firm undisturbed
natural ground surface. The settlement of a one Foot wide continuous footing loaded to
2500 pounds per lineal Foot and Founded on suitable undisturbed natural soils is estimated to
be less than l/8 inch.
/ 3. The results of the laboratory expansion tests indicate that certain of the clayey
fine sand, silty clay, sandy clay, and clay soils encountered in the investigation would be con-
sidered as “expansive” soils. Therefore, in order to avoid the use of speciaily designed footings
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and slabs, it is recommended that, wherever practicable, the “expansive” soils b&wed to a
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Project No. 71-1OJBF
La Costa Vale No. 1
-2- October 22, 1971
depth of 3 Feet below proposed Flnished grade and be mplaced with nonexpansive soils uniformly
compacted to at least 90 percent of maximum dry density. In filled ground amas, all “expansive ”
soils should be placed at least 3 feet below the Final compacted fill surface.
if “expansive” soils am allowed to mmain in the upper 3 feet below finished grade,
it is recommended that footings and slabs be specially designed. The mquimd special design
will be dependent upon the degree of expansion potential of the soil, the thickness of the layer,
and the location of the expansive layer with respect to the Footings or concmte slabs. The lots
requiring specially designed footings and slabs will be listed upon the completion OF grading.
4. All of the sails moy be satisfactorily compacted in the Fill areas and, when com-
pacted to at least 90 percent of maximum dry density, have a safe bearing capacity of ot least
1650 pounds per squam foot For one foot wide footings placed 1 Foot below the compacted ground
surface. The settlement of a one foot wide continuous Footing placed on Fill soils uniformly com-
pacted to at least 90 percent of maximum dry density is estimated to be on the order of l/8 inch.
It is recommended thot all soft, loose, or compressible solls existing in proposed
compacted filled ground areas be removed as required by the soils engineer and the compacted
filled ground be placed on Firm natural soils.
Recommendations for the placement of Filled ground are presented in the attached
“Standard Specifications for Placement of Compacted Filled Ground, ” Appendix AA.
5. A. Post experience is making excavations in the silty clay and.clayey silt formations
in the La Costa area has indicated that the slopes should be cut on a slope ratio OF 2 horizontal
to 1 vertical or Flatter. It should be noted that any cut slopes in amas such as the plastic clay
and claystone below 8.5 Feet in Boring 5-11 should be na steeper than 3 horizontal to 1 vertical.
It is concluded from the test data that cuts made in other types of soils and rock formations may
be safely excavated on a slope ratio of 1 l/2 horizontal to 1 vertical far heights up to at least
50 Feet. Slope stabllity analyser ore shown on Drawing Nos. 22 and 23.
8. The Fill soils, when uniformly compacted to at least 90 percent of maximum dry
density in accordance with the approved specifications, will be stable with an adequate factor
of safety when constructed on a 1 l/2 horlzontal to 1 vertical slope for heights up ta 30 feet.
The above conclusions assume that suitable erosion control and proper drolnage
will be provided to prevent water from running over the top of exposed slopes.
6. Both cutting and filling are required for development of the site. Residences
may be constructed partly on cut and partly on fill provided the load-settlement characteristics
of the natural soils ond the compacted Filled ground om comparable.
If any soil types ore encountemd during the grading operations that worn not tasted in this
investigation, additional laboratory tests will be conducted in order to determine their phyrical
characteristics and supplemental mports and recommendations will autamaticolly become a part
of the specifications.
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BENTON ENGINEERING. INC.
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Project No. 71-lo-18F
La Costa Vale No. 1
-3- October 22, 1971
The data presented on page 1 to 8, inclusive, and on Drawing Nos. 1 to 23, inclusive, or
well as Appendices AA, A and B, am o part of this report.
Respectfully submitted,
BENTON ENGINEERING, INC.
Reviewed by/m aw
William G. Catlin, Civil Engineer
Distr: (4) Roncho La Costa, inc.
(2) Ranch0 La Costa, Inc.
Attention: Mr. Burton L. Kramer
(2) Rick Engineering Company
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Project No. 71-lO-18F
La Costa Vale No. 1
-4- October 22, 1971
PRELIMINARY SOILS INVESTIGATION
Discussion
A preliminary soils investigation has been completed on the proposed La Costa Vale Unit No.
1; located northwest of the intersection of La Costa Avenue and Ranch0 Santa Fe Rood,
San Diego County, California. The location is more specifically referred ta as a portion
of Section 31, T. 12S., R. 3W., portions of Section 36, T. 12S., R. 4W., portions of
Section 1, T 13S., R. 4W., and portions of Section 6, T 13S., R. 3W., San Bemardina
Base and Meridian, San Dlego County, California.
The objectives of the investigation ware to determine the existing sol1 conditions and
physical propertles of the soils in order that engineering recommendations could be pm-
sented for a safe and economical foundation design and for the development of the proposed
building sites. In order to accomplish these objectives, ten borings were drilled, and repre-
sentative undisturbed and laose bag samples were obtained for labomtory testing.
- General
The proposed subdivision is located on the south side of the valley extending easterly from - Batiquitos Lagoon. La Costa Vale Unit No. 1 is located primarily on the higher lands near
the crest of the hills Forming the south rim of the valley. Dminage is primarily northerly;
future dmincge will be into streets and storm dmins.
According to the soil map prepared by the U. S. Department of Agriculture, the upper soils
have been grouped inta four categories. They am as follows: -
1) Altamont clay, which consisk of 0.8 foat of moderately compact clay, 0.9 to
3.5 feet of very compact irregularly calcamous clay, and bedrock. -
2) Olivenhain loamy fine sand, which consisk of 0.5 to 1.4 feet of friable loamy
fine sand, 1.5 ta 1.7 feet of very compact solonek clay, and bedrock, partially consolidated.
3) Muerhuera fine sandy loam, which consists of 0.7 ta 1.4 feet of friable fine
sandy loam, 0.7 Foot of very compact solenek sandy clay loam, 1 .O foot of moderately com- - pact aolumnar sandy clay loam, 1.7 to 1.9 feet of modemtely compact, modemtely calcareous,
fine sandy loam, and slightly compact sandy loam.
- 4) Las Poses stony fine sandy loam, which consisk of 0.5 foot of friable stony fine
sandy loam, 1 .O Foot of slightly compact columnar stony fine sandy loam, 1.1 ta 1.7 feet of
moderately compact stony fine sandy loam, and bedrock. -
The maior soil types encountered in the explomtion holes, as classified in accordance with the
Unified Soil Classification Chart worn clayey sand, sandy clay, claystone, cloy, silty sand,
silty clay, and sandy silktone.
0EI.i ??N E:I’;INiERIP,<.. INC
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-5- Project No. 71-lo-18F
La Costa Vale No. 1
October 22, 1971
Field Investigation
Ten borings wem drilled wlth o truck-mounted rotary bucket-type drill rig at the approximate
locations shown on the attached Drawing No. 1, entitled “Location of Test Borings.” The
borings were drilled to depths of 12 to 63 feet below the exlstlng ground surface. A continu-
ous log of the soils encountemd in the borings was recorded at the time of drilling and is shown
in detail on Drawing Nos. 2 ta 18, inclusive, each entitled “Summary Sheet.”
The soils wem visually classifTed by field identification procedures in accordance with the
Unified Soil Classification Chart. A simplified description of this classification system is
presented in the attached Appendix A at the end of this report.
Undisturbed samples wem obtained at frequent intervals, where possible, in the soils ahead of
the drilling. The drop weight used for driving the sampling tube into the soils was the “Kelly”
bar of the drill rig which weighs 1623 pounds, and the average drop was 12 inches. The general
procedures used in field sampling am described under “Sampling” in Appendix B.
Labomtory Tests
Labamtory tests were performed on all undisturbed samples of the soils in order to determine
the dry density, moisture content, and shearing strength. The resufk of these tesk am presented
on Drawing Nos. 2 to 18, Inclusive. Consolidation tesk were performed on representative sam-
ples in order to determine the load-settlement characteristics of the soils. The resulk of these
tests are presented on Drawing ,Nos. 19 ta 21, inclusive, each entitled “Consolidation Curves.”
The geneml procedures used for the labomtory tesk are described briefly in Appendix 8.
Direct shear tesk were pert&m& on selected laose soil samples remolded to 90 percent of
maximum dry density and on selected undisturbed samples that wem all saturated and drained
prior ta testing. The msulk of these tesk are presented below:
Maximum
Normal Shear
Load in Load
kips/sq ft kipJxl ft
Boring 1, Sample 2 1.35
Depth: 11 .O feet
1.89 1
Boring 1, Sample 6 3.93 3.85
Depth: 31 .O feet
Boring 2, Sample 5 3.37 3.84
Depth: 26.0 feet
Boring 2, Sample 8 5.42 5.06
Depth: 42.0 feet i
Angle of
Internal
Friction
Degrees
Apparent
Cohesion
Ib/sq ft
38.0 820
BENION ECI~~INFERl,l‘~. INC
project No. 71-lO-18F
La Costa Vole No. 1
-6- October 22, 1971
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boring 1, Sample 5
Depth: 26.0 feet
boring 4-11, Bag 2 *
Depth: 4-5 feet
boring 5-11, Sample 2
Depth: 6 feet
Boring l&IV, Sample 3
Depth: 8 feet
boring 19-IV, Sample 2
Depth: 7 feet
boring 19-IV, bag 3 *
Depth: 14-15 feet
NOKlUll
Load in
kips/sq ft
1.0
2.0
4.0
0.5
1.0
2.0
0.5 1.05
1.0 1.98
2.0 2.92
0.5 1.14
1.0 1.65
2.0 3.74
0.5
1.0
2.0
0.5
1 .o
2.0
Maximum
Shear
Load
kips/sq ft
1.43
2.10
3.01
0.70
1.20
1.83
1.07
3.33
1.84
0.52
0.86
1.41
Friction Coharion
Dagrees Ib/sq ft
28.5 900
33.0
44.0
45.0 **
27.0
34.0
390
570
640
820
190
* Remolded to 90 percent of maximum dry density
** Arbitmrily reduced
Using the values of angle of internal friction and apparent cohesion determined as shown above,
and the Terzaghi formula for local shear failure, safe allowable bearing values for the weakest
soils are determined on the following page.
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Project No. 71-IO-18F
La Costa Vale No. 1
-7- October 22, 1971
Local Sheor Formula: Q’d = 28 (2,/3 CNlc + Y Df N’q ;‘- Y BN’y)
(1) Continuous footing 1 foot wide = 28
(2) Depth of footing = 1 foot = Df
(3) Q’ Safe = Q’d3 (Factor of Safety)
ErT ,T~~~~~~ 3 (Remolded to 90 percent of maximum dry density)
Q = 34.00
Nlc = 23.0
c = 190 Ib/sq ft
N’, = 13.0
Y = 120 Ib/cu ft
N’y=8.5
Cl ’ Safe = 2 (190) (23.0) + 120 (13.0)+ 120 (8.5) = 1660 Ib/sq ft
9 3 6
Use 1650 Ib/sq ft
Boring 19-W, Sample 2
Depth 7 feet
4) = 27.00 C 820 Ib/sq ft Y = 119 Ib/cu ft
N’, = 16.5 Nlq = 7.5 N’y = 4.0
Q’ We =2 (820)9(16.5) + 119 ‘37.5) I 119~4.0) = 3386 Ib/sq ft
Use 2500 Ib/sq ft
In addltion to the above labomtory tests, expansion tests were performed on some of the clayey
sails encountered to determine their volumetric change chamcteristics with change in moisture
content. The recorded expansions of the samples are presented as follows:
Percent Expansion
Under Unit Load of
Depth of 150 Pounds per Square
Boring Sample Sample, Soil Foot from Air Dry
No. No. in Feet Description to Saturation
l-11 1 2.0 Gmyish-brown fine sandy cloy 11.50
4-11 1 2.0 Brown clayey fine sand 4.84
4-H
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21 .o Ollve-gmen cloystone 9.16
5-11 16.0 Olive-green cloystone 10.28
16-IV 1A 1.5 Raddish-brawn fine sandy clay 8.18
19-W 1 3.0 Olive silty clay 400
The geneml procedures used for the Iaborotary tests are described briefly in Appendix B.
R, i,,~Oi” tNC.lNiLnliii, #NC
Proiect No. 71-lO-18F
Lo Costa Vale No. 1
-8- October 22, 1971
Compaction tesk were performed on representative samples of the soils to be excavated to
establish compaction criteria. The soils were tested according ta the A.S.T.M. D 1557-66T
method of compaction which uses 25 blows of a 10 pound mmmer dropping 18 inches on each
of 5 layers in a 4 inch diameter l/30 cubic foot mold. The retsulk of the tests are presented
as follows:
Maximum Optimum Mois-
Boring Bag Depth Soil Dry Density ture Content
No. Sample in Feet Description Ib/cu ft % dry wt
l-11 1 l- 2 Greenish-brown fine sandy clay 118.8 12.2
2-11 1 2- 3 - Brown clayey fine ta medium 128.0 9.2
sand
4-11 2 4-5 Gmyish-brown silty fine sand 117.0 13.1
14-15 118.5 12.0 - 19-IV 3 Light brown silty fine ta
medium sond
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BORING NC, 1, ,.....
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Dark Gray,‘~Sfig’htly Moist, . . . : ‘LL 7 ” “‘.”
Dark Olive-gray With Orargc-
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Badly Jointed Claystone
Light Olive-brown to Light -
Brown, Moist, Very Fim
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0 - Irdicotes Undisturbed Drive Sanple
* - The elevations shown on these Summary Sheets were obtained by Interpolating
between contoun shown on a topographic drawirg prepared by Rick Engineering
Company, dated October 15, 1969.
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BORING NO ..--!!.@‘+ .)
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Light Gray-brown, With Ororge
brown, Moist, Very Finn,
Pockets of Slightly Silty Fine to
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SAND
Light Olive-gray With Orange-
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Pockeh of Slightly Silty Fine
to Medium Sard and Silty Fine
SWd
SILTY CLAY
Light Olive-gray With Some
Purple, Moist, Very Firm
th Oroqe- SILTY CLAY
(CLAYSTONE)
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Light Olive-grey With Ororqe-
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SILTY CLAY
(CLAY~T~NE)
Continued on Drawing No. 5
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BORING rdo ..I (he.)
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ight Olive-gray With Orange-
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SILTY CLAY
(CLAYSTONE)
Continued on Drawing No. 7
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SUMMARY SXEET
BOR!NG MCJ ,.... ?. .(Cont.)
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ht Olive-gray With Dark
rarge-brown, Moist, Very
Light Olive-grey With Dark
Oroqe-brown ‘tith Light
YeIlow-brown, Moist, Very
Firm, 10 Percent Gravel and
Concretions to 2 inches,
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PROJECT NO $i~Lr,i f <‘:‘:4 EP1G:i-itiERING.
-L
:l%a’!f,N~ NO
-?4l+aEP !fVC. 8
_,-...I_ ..*.- L._. II .-_,,, _y_ ___-___ ~
-
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1
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-_ ._-,. ,_-.,,___ .“-~..,-_A_
SUMMARY SHEET
BORING NON d..dJ
EiEVATIOfI ___ !.&t-*
YulM,----
ray-Brown, Slightly Moist,
-- ---
-- ----
- -&own ond Groy
-- _.__-.--
Light Groy, Moist, Very Firm
,_.----_ .-.,-. ~.
:LAYEY FINE SAN
INE SANDY CLA)
1
CLAYSTONE
--
:, Y :; w . z Y: 641 9:
ui Y
2:.
0
8.1
6.5
8.1
.I w.,
?, . a.! >3 it;: ;3:
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-
14.:
19.7
13.6
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-
04.’
03.1
-
14.1
-
4.3(
2.85
--.
1.43
cl Indicates loor, bog sample
0 Indicates undistrubed drive sample
* The elevations shown on these Summary Sheets were obtained by interpolating
between the contours on o mop provided by Rick Engineering Company of
Son Diego.
-..--+-~. ,,.v, ~.,_ .A..~_ .~~ ..,,. .^ .,_-- I--.~ --,. ., .- . ..., ,.,. ._ ..” PROJECT NO. -,i., ,, .>,(
:.;; I 4 I i,)ij ENGINEERlb!G, IP~li: 2 ‘:
-./, _.., .,._.” ,_._.^__l_l_ 9 y,~~.l^--l “....~... .., . _ _-.,. “.,. .._ :
ij, . ,.,*
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c1 $2 Y
ttlV*f!wi Jx! _____ ;> _
]a u
“-~~Brown, Dry, Loose
+--.- I .__--.. . . ..___.- ” L _-- -
Medium Firm, Mottled With
Clayey Fine to Medium Sand
Occo~ionol Chunks of Fine
Scattered
_.,...... -,-,-__ _
Brown, Moist, Contains Fine
ray, very MolV, Soft
CLAYEY
FINE
SAND
._-
(~ws)- II
ray-Brown, Medium Firm
I_-..-
:;--@Llght Groy, Moist, Firm
FINE SANDY
CLAY
:LAY, MERGING
‘0 CLAYSTONE
(
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.-
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_.UIsm..-.~al-- __-- ..-.. ..-e,~-..-..
SUMMARY SHEET
BORING NOA:..JI,
tlti,;Af@N _.. ??te.
_--... _~___~~. -_
Light Brown and Light Grey i SILTY VERY
Moist, Very Firm I FINE TO
1 FINE SAND
I
/
Continued on Drawing No. 5
--
. ~~~ - ..~ _...L.~-,-.-~_ll,,,-_ ,.. --. .~__-.- I_
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I 3::: SUMMARY SHEET SL Et! 22 BORING NO.4-ILont’d)
% 52
-.~-.
Brown and Light Groy,
,&Firm -.- . . . __-,____
ight Olive Green, Moist,
Very Firm, Highly Fractured
More
-
Massive
30-
@a
3u ____
I - .,_ _.-- ~.^. .,-.~
‘ILTY VERY FINE
*NE SAND
C LAYSTONE
--m.~. i
2 ,i
r E.
Er
Al’i
;=
3 _. .--
-
16.2
54.‘:
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-
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z z:: SUMMARY SHEET XL iit! 22 BORING NO..LZL.L- 2 s,l, ELEVATION a...298’
L;ght Brown and Light Gray,
7c 4
is : 3 !
Moist, Very Firm,
Plastic, Showr lndicotionr of
___~,__ -
Brown, Moist, Very Firm
--___ ~_--
Olive Green, Moist, Very
r0 FINE SAND
CLAY
SILTY FINE
SAND
CLAYSTONE
16.2
-
!2.7 --
9.7
! 1
1
1
-
16.1
16.4
.-
~~~--.
7.t
a.9
06.2 2.1(
x.2 2.25 ---
)7:2 7.3’:
> Continued on Drawing No. 7
PROJECT NO.
-. .- _^_
.d~ -I_-
BENTON ENGINEERING, INC.
I.
DRAWING NO.
* 13 --_.
- r
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I ._-.. .__._ I ..,. __ -___ ~-.~-.-- ._~~
Olive Green, Moist, Very
Firm, Fractured
4
I 3 Degrees Approx. N. 70” /
~~dF$to&~urn So; and j
01;~ Green and Brown, Pockets
,
C LAYSTONE
/ j
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16.2! 17.8 I1 13.0
13.: 3/z
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1.43 j
* Shear resistance exceeded 7 50 kips per square foot, the limit of shear machine.
~gg&pO, ORAWiNG *IO
BENTON
m=a=m ENGINEERING, INC. I
---A- _,_-- .“.“-. - w -, I
: .I 8’
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SUMMARY SHEET
BORING NO.-v!z&
ELEVATION -- 170’ l
t
ark Brown, Slightly Moist,
se, 10 to 15 Percent Rock
Frogrnents to 2 Inches
-- -,.. -----_.-_
rown, Moist, Firm, 20 to
25 Percent Gravel and Cobbles,
With Rock Fragments to 8 Inches
lght Olive-gray and Light
ad-brown, V89’ kilt,
Medium Soft, Contains Medium
to Coarse Grains Between 6.6
-- - .~.. _~__~ __.. -.-.- ---
t
/
FINE TO MEDIUM
SANDY CLAY
4.9; 10.11 89.01 - /
---- -my--+---
cL;z;;h; TO 113.0; 8.7; - -
MEDIUM
SAND I ,
_ ._.-_.-
Very Firm
I ,
: 1.6 ,19.4 lQ7.8 1.94;
SILTY
CLAY
/
!
II I
/ / I
3.2’19.7il05.7; 1.201
e - Indicates Undisturbed Drive Sampie
l - The elovatlons shown on these Summary Shoats were obtalned by interpolating
between the contours on a map provided by Rick Engineerlng Company of
San Dlego.
PROJECT NO.
BENTON DRAWING NC ENGINEERING, INC. -e 15
!
I
16.2: 12.6J13.014 ““I ..--i.-,-L--i-
,,~I.,. ‘
I 1
/
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2. _ 2
> 0: +i 5;
. 2:; -
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_ $I 4:
-1 B -. ‘-1 I
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5
-
SUMMARY SHEET
BORING N0.16~~
ELEVATION .vmw
r
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t
/
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‘_-.-.._- _____^_ -.-.-
~c+?!n,. -- E!lLk?s_e .__- --
Slightly Moist, Firm
Light Groy, Light Brown and
Red-brown, Moist, Very Firm
. ..-.._ -_ -____
Light Gmy ‘Nith Yellow-brown
and Brown, With Zones of Very
Fine Sandy Clay, Lean
6 ‘.
Light Groy With Yellow-brown
and Brown, With Zones of Very
Fine Sandy Clay, Lean
.- I FINE SANDY
CLAY
SILTY VERY
FINE SAND
CLAYEY VERY
FINE SAND
I
1 i
8.1
!4.3 -
-j---p-
I ’ i
I 1 14.6 11, - -l ,8 1
PROJECT NO.
I BENTON -4.--m ENGINEERING, INC. I DRAWIN(i NO.
2S 16’
-
-
-
-
‘:,
-
I-
.-
1 ./ I
;“; iL[
i $ZG/ ,rL?%: i kj “Ssi 0; XI
-~-F---f-
I zL-5 SUMMARY SHEET It; Elt 22 2% BORING NO.ISJv
z ElEVATlOh 1__1 223’ ---
Dry, Loose, Porous,
Podtets of Clay and Sand
..- ~--.. --.--
k-
!
/
I
1
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I
I /
/
I I 1 /
4...
/ 1 I
jll
--
Slightly Moist, Firm 8.1 13.4
CLAYEY FINE TO
MEDIUM SAND
/
12.8
I 6 .t j i
1
!
32.8:
---t---i--
i j
I I
I
-_----.-- --...~.
Olive, Moist, Very Firm
SILTY CLAY
8.1 10.4
2.4
14.lj
I
I
I / I I
-
I 1
j
L 11.4 12.9 -_ l.
PROJECT NO.
w4-w
DRAWING NO. BENTON ENGINEERING, INC. 97 17
-
r
;r zz SUMMARY SHEET XL I
p’,” 2: BORING NQ.19-ly
: $2 ELEVATION 235’
zt $$ :c”‘ ‘Ci -> -
-
-
-
-
-
5 (: CLAY
-
-
-
-
:LAYEY FINE TO
D 2 Olive, Dry, Very Firm
Oiive, Moist, Very Firm
-
,7.1
9.;
-
-
7.3
2.7
to.:
!l .A
-
-
2.1
7.0
98,
P8,
-
-
‘3i;.
17.’
SILTY CLAY
-
Olive, Moist, Very Firm
FINE SANDY
SILTSTONE -
L
-
-
-
-
-
-
I
+ CLAYSTONE
LENS Olive, Moist, Very Firm
Light Brown, Moist, Very Fim t
I
!
iS
I E
SLIGHTLY
ILTY FINE TO
AEDIUM SAND
- - -
PROJECT NO. DRAWING NO. BENTON ENGINEERING, INC. -28 18
-
-
-
1
2
-
-
-
I
-
-
-
-
CoNSOI,-i’3~?-iON CURVES
LC ; ” i Y KIPS PER SOUARf FOOT
i /
/ ; / i
--L.-L ’
/ / !.‘i!J
I I
0 INDICATES PERCENT CONSOLIOATION AT FIELD MO,STURE
. IHDr,ATES PERCENT CONSOLIDATIOH AFTER SATURATION
L
.-
-
-
-
-
-
-
-
-
-
-
LOiO !ii k&F’8 PER SQUARE FCUiT
-
PROJECT NO.
‘9 INDICATES PCRCFNT CONSOLIDATION AT FIELD LIO,S,~,RE
. !NDICAIES PERCENT CONSOLIDATION AFTER SATliRATlON
-____ -..-.,. ~-_ _.“. - -.,l--l_ll ----I
BENTON ENGINEERING, INC I DRAWING NO,
a4 2@ I
; , , I L I I ,
.
I : , i
;
: 2 z
CONSOLIDATION CURVES
LOAD IN KIPS PER SPlJAllf FOOT
i i I .I 4. / / / i j I I i aim .%-I~
0 ---~+ ,.~~--.‘.
IL
Jo.. +. ~,., .t...+ ..~ ...~~~~. ..-.
i i ;/!;I
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I: ‘:: ,~, &.[: ::tf ,;:i ,,j’ ~:, ,{j:: : ~,,,:“, “,
,~:~~
P-IV -1
0 INDICATES PERCENT CONSOLIDATION AT FIELD UOISTuRE
PROJECT NO.
. ,,dDIC.TES PERCENT CONSOLlC4TlON AFTER SATdRAriOU
-.-_-- ^,- --- -.-
DRAWINO NO. BENTON ENGINEERING, INC. aa 21
&;:+ ,’
./I / ! ,z. I
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1: /
4 ,/ ,/,’
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9:
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~&1: /()(P . .;.; f. ~~~, /-, j ..i "., c, &\, / _,;, '. , ,; ':I'.-'. I‘,, .,/ '1
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G,;-- (: ;); :r:'jr5,.y~ \;{.Q _ j K T/.4:'!.:' .,":. 4, 5!2i~. : ,..,I :':& :.,. >
FILL LPC’ :
@= 33’ c=Em
ES.= 19c~(70.9)+ 56,dh.m399 _ ~.~~ ~~~. ~~
34,050
/>S d-.. _.. .~. ,.~ . .._. ..,...
FL&, J&.,‘~ OneQ -GA*J Ptism
C&t/ OK Cr*vsTt?dE
-. .
1
-cl
:+
/‘
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Li- iLcIE ‘. @= 27O c=020
KS.= 82406) + l,d.L(L~~“) j?! --- _._ ~,____ 5 /.a F-m JOlLS ~rm.-heJ
77.3 - ihAmc c coy orz c caYs-w%
.’ .\,
“\\.
- BENTON ENGINEERING. INC.
APPLIED SOIL MECHANICS - FO”NDA.TIONS
6741 EL CAJON IIOULEVARD S&N DIEGO. tA.LIFORNIA 0.2,1s
-
-
-
-
-
-.
-
-
--
-
-
-
PHlLlP HENKING BENTON ,“E*101*1. ClVlL CNGIUIEI SAN DmCc.: r,l)3-!lB84 LA “r*r: .e*.s*,4
APPENDIX AA
STANDARD SPECIFICATIONS FOR PLACEMENT
OF COMPACTED FILLED GROUND
1. General Description. The objective is to obtain uniformity and adequate internal strength
in filled ground by proven engineering procedures and tests so that the proposed structures
may be safely supported. The procedures include the clearing and grubbing, removal of
existing structures, preparation of land to be filled, filling of the land, the spreading,
and compaction of the filled areas to conform with the lines, grades, and slopes as shown
on the accepted plans.
The owner shall employ a qualified soils engineer to inspect and test the filled ground as
placed to verify the uniformity of compaction of filled ground to the specified 90 percent
of maximum dry density. The soils engineer shall advise the owner and grading contractor
immediately if any unsatisfactory conditions are observed to exist and shall have the
authority to reject the compacted filled ground until such time that corrective measures
are taken necessary to comply with the specifications. It shall be the sole responsibility
of the grading contractor to achieve the specified degree of compaction.
2. Clearing, Grubbing, and Preparing Areas to be Filled.
(a) All brush, vegetation and any rubbish shall be removed, piled, and burned or other-
wise disposed of so as to leave the areas to be filled free of vegetation and debris.
Any soft, swampy or otherwise unsuitable areas shall be corrected by draining or
removal, or both.
(b) The natural ground which is determined to be satisfactory for the support of the filled
ground shall then be plowed or scarified to a depth of at least six inches (6’7, and
until the surface is free from ruts, hummocks, or other uneven features which would
tend to prevent uniform compaction by the equipment to be used.
(c) Where fills are made on hillsides or exposed slope areas, greater than 10 percent,
horizontal benches shall be cut into firm undisturbed natural ground in order to pro-
vide both lateral and vertical stability. This is to provide a horizontal base so that
each layer is placed and compacted on a horizontal plane. The initial bench at the
toe of the fill shall be at least 10 feet in width on firm undisturbed natural ground
at the elevation of the toe stake placed ot the natural angle of repose or design
slope. The soils engineer shall determine the width and frequency of all succeeding
benches which will vary with the soil conditions and the steepness of slope.
-
r-
-
-
-
-
-
-
.--
-
-
-.
-
-
.F^~ -
3.
4.
APPENDIX AA
-2-
(d) After the natural ground has been prepared, it shall then be brought to the proper mois-
ture content and compacted to not less than ninety percent of maximum density in
accordance with A.S.T.M. D-1557-66T method that uses 25 blows of a 10 pound hammer
falling from 18 inches on each of 5 layers in a 4” diameter cylindrical mold of a 1/30th
cubic foot volume.
Materials and Special Requirements. The fill soils shall consist of select materials sograded
that at least 40 percent of the material passes a No. 4 sieve. This may be obtained from
the excavation of banks, borrow pits of any other approved sources and by mixing soils from
one or more sources. The material uses shall be free from vegetable matter, and other de-
leterious substances, and shall not contain rocks or lumps of greater than 6 inches in diameter.
If excessive vegetation, rocks, or soils with inadequate strength or other unacceptable physical
characteristics are encountered, these shall be disposed of in waste areas as shown on the
plans or as directed by the soils engineer. If during grading operations, soils not encountered
and tested in the preliminary investigation are found, tests on these soils shall be performed to
determine their physical characteristics. Any special treatment recommended in the preliminary
or subsequent soil reports not covered herein shall become an addendum to these specifications.
The testing and specifications for the compaction of subgrade,subbase, and base materials for
roads, streets, highways, or other public property or rights-of-way shall be in accordance
with those of the governmental agency having jurisdiction.
Placing, Spreading, and Compactiw Fill Materials.
(b)
Cc)
(4
The suitable fill material shall be placed in layers which, when compacted shall not
exceed six inches (6”). Each layer shall be spread evenly and shall be throughly
mixed during the spreading to insure uniformity of material and moisture in each layer.
When the moisture content of the fill material is bellow that specified by the soils ergineer,
water shall be added until the moisture content is near optimum as specified by the
soils engineer to assure thorough bonding during the compacting process.
When the moisture content of the fill material is above that specified by the soils
engineer, the fill material shall be aerated by blading and scarifying or other sotis-
factory methods until the moisture content is near optimum as specified by the soils
engineer.
After each layer has been placed, mixed and spread evenly, it shall be thoroughly
compacted to not less than ninety percent of maximum density in accordance with
A.S .T.M. D-1557-66T modified OS described in 2 (d) above. Compaction shall be
accomplished with sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other
approved types of compaction equipment, such as vibratory equipment that is specially
designed for certain soil types. Rollers shall be of such design that they will be able
APPENDIX AA -
-
-
-
-
-
-
-
-
-.
-
-
,- -
-
5.
6.
7.
8.
(e)
(9
kl)
-3-
to compact the fi II material to the specified denslty. Rollirrg shall be accanplished
till@ the ffll material is at the specified moisture content. Rolling of each layer shall
be continuous over lk entire area and the roller shall make sufficfent trips to insure
that the desired density has been obtained. The entlre areas to be fllled shall be
compacted.
Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment.
Compacting operations shall be continued until the slopes are stable but not too dense
for planting and until there is no appreciable amount of loose soil on the slopes.
Compacting of the slopes shall be accomplished by backrolliq the slopes in Increments
of 3 to 5 feet in elevation gain or by other methods producing satisfactory resulk.
Field density tests shall be taken by the soils engineer for approximately each foot in
elevation gain after compaction, but not to exceed two feet in vertical height between
tests. Field density tests may be taken at intervals of 6 inches in elevation gain if
required by the soils engineer . The location of the tesk in plan shall be so spaced to
give the best possible coverage and shall be taken no farther apart than 100 feet. Tests
shall be taken on corner and terrace lots for each two feet in elevation gain. The soils
er\gfneer may take additional tests as consfdered necessary to check on the uniformity
of compaction. Where sheepsfoot rollers are used, the tests shall be taken In the com-
pacted material below the dlsturbed surface. No addi tlonal layers of fl II shall be spread
until the ffeld denslty tests indicate that the specified density has been obtalned.
The ftll operation shall be continued in six inch (6”) compacted layers, as speclfled
above, until the fill has been brought to the finished slopes and grades as shown on
the accepted plans.
?I@?- Sufficient Inspection by the soils engineer shall be maintalned during the
fl 1~ an compactirrg operations so that he can certify that the fill was constructed in
accordance with the accepted specifications.
Seasonal Llmlk. No fill material shall be placed, spread, or rolled if weather conditions
increase the moisture content above permissible limits. When the work is interrupted by
rain, fill operations shall not be resumed until field tests by the soils errgineer indicate that
the moisture content and density of the fill are as previously specified.
Limi tlrg Values of Nonexpansive Soi Is. Those soils that expand 2.5 percent or less from
air dry to saturation under a unit load of 500 pounds per square foot are considered to be
nonexpansive.
All recommendations presented in the “Conclusions” section of the attached report are a
part of these speclflcatlons.
SENTON CNOINLLIINO. INC.
-
-
-
-
-
-
-
-
-
-
-
-
-
-.
-
-
-
-
BENTON ENGINEERING, INC.
APPLIED SOIL MECHANICS - FOUNO*TION*
674, EL CAJDN BOULEVARD S&N DIEGO. CILIFORNI& 92115
PHlLlP WENKINO BENTON PI)L,,DINI ClYlL LYcsIHEFm APPENDIX A
Unified Soil Classification Chart*
SOIL DESCRIPTION GROUP
SYMBOL
I. COARSE GRAINED. More than half of
material is larger than No. 200 sieve
size.**
GRAVELS CLEAN GRAVELS
s half of
coarse fraction is
larger than No. 4
sieve size but smallerGRAVELS WITH FINES
than 3 inches (Appreciable amount
of fines)
SANDS CLEAN SANDS
man half of
coarse fraction is
smaller than No.
4 sieve size SANDS WITH FINES
(Appreciable amount
of fines)
II. FINE GRAINED, More than half of
material is smaner than No. 200
sieve size. TILTS AND CLAYS
Liquid Limit
Less than 50
SILTS AND CLAYS MH
Liquid Limit
Greater than 50
Ill. HIGHLY ORGANIC SOILS
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
CH
OH
PT
TYPICAL
NAMES
SAN DIEGO: 5119-S6S4 LA HE,*: 469.5654
Well graded grovels, gravel-sand mixtures,
little or no fines.
Poorly graded gravels, gravel -sand
mixtures, little or no fines.
Silty gravels, poorly graded gravel-
sand-silt mixtures.
Clayey gravels, poorly graded gravel-
sand-cloy mixtures.
Well graded sand, gravelly sands, little
or no fines.
Poorly groded sands, gravelly sands,
little or no fines.
Silty sands, poaly graded sand-silt
mixtures.
Clayey sands, poorly graded sand-clay
mixtures.
Inorganic silts and very fine sands, rock
flour, sandy silt or clayey-silt-sand
mixtures with slight plasticity.
InMgonic clays of low to medium plas-
ticity, gmvelly clays, sandy clays,
silty cloys, lean clays.
Organic silts and aganic silty-clays of
low plasticity.
Inorganic silk, micaceous cr diatoma-
cecus fine sandy or silty soils, elastic
silk.
Inorganic clays of high plasticity, fat
clays.
Organic clays of medium to high
plasticity.
Peat and other highly organic soils.
* Adopted by the Carps of Engineers and Bureau of Reclamation in January, 1952.
** All sieve sizes on this chart are U.S. Standard.
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BENTON ENGINEERING. INC.
APPLIED SOIL MECHLNICS -~- FOuNO*T,ONS
6741 EL CAJON BOULEVARD *AN DIEDO. CALICCJRNIA 82115
PHILIP HENKING BENTON PRE*oDENT ClVlL ENWNFFR APPENDIX B 5** Dlroo: 5.83.S654 L* MLSA. d69-5654
Sampling
The undisturbed soil samples are obtained by forcing a special sampling tube into the
undisturbed soils at the bottom of the boring, at frequent intervals below the ground surface.
The sampling tube consists of a steel barrel 3.0 inches outside diameter, with a special cut-
ting tip on one end and a double ball valve on the other, and with a lining of twelve thin
brass rings, each one inch long by 2.42 inches inside diameter, The sampler, connected to a
twelve inch long waste barrel, is either pushed or driven approximately 18 inches into the soil
and a six inch section of the center portion of the sample is taken for laboratory tests, the soil
being still confined in the brass rings, after extraction from the sampler tube. The samples are
taken to the laboratory in close fitting waterproof containers in order to retain the field mois-
ture until completion of the tests, The driving energy is calculated as the average energy in
foot-kips required to force the sampling tube through one foot of soil at the depth at which the
sample is obtained.
Shear Tests
The shear tests are run using a direct SheW machine of the strain control type in which
the rate of deformation is approximately 0.05 inch per minute. The machine is so designed that
the tests are made without removing the samples from the brass liner rings in which they are se-
cured. Each sample is sheared under a normal load equivalent to the weight of the soil above the
point of sampling . In some instances, samples ore sheared under various normal loads in order to
obtain the internal angle of friction and cohesion. Where considered necessary, samples are
saturated and drained before shearing in order to simulate extreme field moisture conditions.
Consolidation Tests
The apparatus used for the consolidation tesk is designed to receive one of the one inch
high rings of soil as it comes from the field. Loads are applied in several increments to the upper
surface of the test specimen and the resulting deformations are recorded at selected time intervals
for each increment. Generally, each increment of load is maintained cm the sample until the
rate of deformation is equal to or less than l/10000 inch per hour. Porous stones are placed in
contact with the top and bottom of each specimen to permit the ready addition or release of water.
Expansion Tests
One inch high samples confined in the brass rings are permitted to air dry at 105°F for
at least 48 hours prior to placing into the expansion apparatus. A unit load of 500 pounds per
square foot is then applied to the upper porous stone in contact with the top of each sample.
Water is permitted to contact both the top and bottom of each sample through porous stones.
Continuous observations are made until downward movement s,tops. The dial reading is recorded
and expansion is recorded until the rate of upward movement is less than l/10000 inch per hour.
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