HomeMy WebLinkAbout; La Costa Greens; Soils Report Final; 1970-05-28L 5673
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PHlLlP HENKING BENTON PIFSIDLNT ClYlL CNOINIC”
Ranch0 Lo Costa, inc.
Rwh 1, Box 2550
Encinitas, California 92024
BENTON ENGINEERING, INC.
APPLIED SOlL MECHANICS ~.,- FOUNDITlONS
6741 EL CAJON mOULE”*RD *AN DIE00. CALIFORNIA 921,s
May 28, 1970 6AU DIEGO: ,I)J-S6S4 LA MIS*: .6*-s=*.
Subject: Project No. 69-lo-24D
Fimi Report on Ccmpachd Filled Ground
and Recommendations for Sicpa Stability
and Soil Bearing Values
La Costa Green
North of La Costa Avenue
East of El Camino Real
San Diogo County, California
Permit No. L5673
Gentlemen:
This is to report the rosuits of tests and obrrvatiotn mode in order to inspect the compaction
of fiiiod grwnd placed on certain aroas of Lots 1 to 10, inciusive, La Costa Greens, being
a Subdivision of a Portion of kctiom 35 and 36, Township 12 South, Rarge 4 West, S.B.B.b
M. San Diego County, California. These fills wire placed during the period between October
24, 1969 and May 15, 1970.
Reference is made to wr report of Proiect No. 69-6-12C, doted January 20, 1970, in which
M stated that stability of thr slopes wwid be confirmed and rrcommendations for dosign of
safe and economical fwndatiom would be made after the grading was completed. These items
will be discussed further on Pqe 2 of this report.
The approximate areas and depths of filled ground placed under wr impaction in accordance
with the approved specifications ore shown on Drawig No. 1, entitled “Location of Compacted
Filled Grwnd. ” The gradinp plon used for the placement of filled ground was prepared by
Rick Eginoerirq Company and dated January 26, 1970. Pioase note that a portion of the filled
ground was placed over compressibio ground. This orea is roforred to on Drowirg No. 1 as, “fill
placed over ccmpressibie ground.” It is recommended that spciai design precwtions be exercised
in this area to minimize possible damqe to the sttucture CII a result of sottlemont.
The approximate locations at which the tests were taken and the final test results are p-ant&
on ~910 Tl to T4, inclusive, under the “Table of Test Results.” The laboratory determimtiwr
of the maximum dry dersttios and optimum moisture contents of ho maior fill matariais are
pmsrnkd on pqe T5, under the “Laboratcry Test Rosuik.” Some of he maximum dry demities
shown in the ktbir of test results wre combimtiom of thesr. The tests wire taken during the
mekiy periods indicated on the foilowirg pqe.
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.17.73
c.2
Project No. 69-IO-24D
La Costa Greens
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Test Number Week Ending
1 October 24, 1969
2 October 31, 1969
3afd4 November 14, 1969
5 to 33, inclusive November 2 1, 1969
34 to 86, inclusive December 19, 1969
87 to 101, lnciusiv. December 26, 1969
102 to 119, inclusive May 8, 1970
120 to 141, inclusive May 15, 1970
- The final results of tests and observations indicate that the filled ground, placed under wr
ilrpection, has been canpacted to 90 percent of maximum dry deraity or greater.
- Direct shear tests vmr. performed on selected loose soil sonpies remolded to 90 percent of
maxlmum dry denri ty that mre ail saturated and drained prior to testig . The results of these
tests are presented below: -
Sample 1
Normal
Load in
kiprhq ft
0.5
1.0
2.0
Maximum Agi. of
Shear internal
Load Friction
kips/sq ft Degrees
1.10
1.21 29.3
1.94
ib/sq ft
650
Sample 2 0.5 0.85
1.0 1.17 16.0 700
2.0 1.46
Sample 3 0.5 0.65
1.0 ,0.72 9.2 575
2.0 0.88
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Appiyirg the Terzaghi Formula to the results of the above tests indicates that the fiti materiais
ccmpacted to 90 percent of maximum dry density have a safe bearirg value of 1300 pounds per
- square foot for on. foot wide contirvous footings founded at a minimum depth of two feet below
the iomrt adjacent grwnd level, and placed five feet or more inside the top of compacted
filled ground slopes. If footings are placed closer to the exposed slopes than five feet imide
- the top of compacted filled ground slopes, these shwld be deepened on. foot below a om and
om half horizontal to on. vertical line prolected outward and downward from a point five feet
horlzontaiiy irmide the top of the compacted filled ground slopes. Tests indicate that the can-
- pacted tl lied ground is adquate to satisfactoriiy support on. or two story wood frame dweiiirgs
desigmd for the recommended bearing value without detrimental settlements in the areas where
the compacted filled ground is placed wer stable natural ground. No accurate prediction can
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BENTON ENGINEERING. INC.
Project No. 69-IO-24D
La Cceta Greenr
-3- May 28, 1970
be made concernirgl the settlement for structures placed on the compacted filled ground overlying
the “compressible ground” areas shown on Drawig No. l!, However, it is understood that the
foundation design used for the Stables and the Maintemnco Building, which were both placed
over similar compressible soiis, has been performing satisfactoriiy. it is recommended that the
sane design criteria be used for structures in these area.
Through tests and observations it has been determimd that expansive soils exist in the upper
three feet below finished grade on ail of the lots covered by this report. it is therefore recom-
mended that the following special design precaution be taken for the hwses to be constructed
on these lots.
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1. isolated interior piers shwid not be used. Continuous footigs should be used
throughout, and these should be placed at a minimum depth of two feet below
the iov+ast adjacent exterior final ground surface.
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2.
3.
4.
Reinfcrce and interconnect continuously with steel bars ail interior and exterior
footirgs with om #5 bar at 3 inches above the bottom of ail footings and one ‘5
bar placed 1 l/2 inches below the top of the stems of the footirgs.
Use raised wood floors that span betwon continuwr fwtigs, or reinforce ail
concrete slabs with 6 x 6 - IO/IO woven wire fabric and provide a minimum of
4 inches of clean sand beneath ail concrete slobs. provide a moisture barrier
2 inches below slabs under livirg areas.
Separate garage slabs from perimeter fwtigs by l/2 inch thickness of construc-
tion felt or equivalent, to allow independent movement of garqe slabs relative
to perimeter footirgs.
5. Provide positive dmirqe away from ail perimeter footings to a horizontal
distance of at least 6 feet wtside the hwse wails.
it is concluded from the test data that the flii soil4 when uniformly compacted to at least 90
percent of maximum dry demity in accordance with the approved specifications, will be stable
for heights up to 28 feet when constructed on a 1 l/1 horizontal to 1 vertical, or flatter slopes.
A stability analysis for the proposed fill slope is presented on Drawirg No. 2, Hhichdemon-
strates a safety factor of 1.5 arsumitg a horizontal seismic force of 0.1 g . The above conclusion
assume that erosional control and proper drainage to prevent surface water from running aver the
top of exposed slopes will be provided.
Pqes Tl to T5, inclusive, and Drawirg Nos. 1 and 2, are a part of this report. -
Respectfully submitted,
- BENTON ENGINEERING, INC. - B Reviemd
William C. Catiin, Civil Engineer
- Distr: (3) Addressee
(2) Mr. B. L. homer BENTON ENGINEERING. INC
IR\ Pi-L S..s.l..ur:.m Cr...mm....
Proiect No. 69-IO-24D
La Costa Greera
Test
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
:
38
Approx- D.Ph
imate of Flli
Location at Test
Lot No. in Feet
1
2
7
3
:
7
9
3
2
1
6
8
10
5
7
5
4
10
9
6
9
3
5
2
1
4
3
8
7
4
5
6
7
5
3
1
6
4
7
3 13.3 105.5 115.8 91.2
2 13.2 108.0 119.9 90.1 * 12.3 119.8 124.2 96.4
1 13.2 109.6 121.0 90.6
2 11.9 115.1 122.1 94.3
4 11.0 114.3 122.1 93.7
2 13.5 112.9 122.0 92.6
2 10.4 113.1 122.1 92.6
4 10.1 1FO.O 122.1 90.1
6 14.6 111.1 120.5 92.2
7 11.2 115.2 122.1 94.4
4 9.8 111.8 122.1 91.6
4 10.4 114.2 122.1 93.5
2 12.2 113.9 120.5 94.5
6 11.3 108.2 121.6 89.1
6 12.6 109.6 119.9 91.5
6 12.3 109.3 120.5 90.8
8 13.3 111.8 121.0 92.4
6 13.1 112.9 121.0 93.4
6 13.7 113.1 120.5 93.9
8 11.9 108.7 119.9 90.7
8 13.0 111.0 121.0 91.8
8 12.1 111.1 120.0 92.6
10 14.4 111.2 116.4 95.6
10 14.4 114.1 120.0 95.2
11 15.2 112.2 120.0 93.6
12 14.7 112.2 120.0 93.6
12 14.8 110.4 120.0 92.0
8 12.8 114.4 122.1 93.7
10 10.4 115.6 124.2 93.1
16 13.9 117.3 122.1 96.1
14 13.7 111.9 123.2 90.8
12 12.2 110.8 121.0 91.6
14 10.3 114.1 122.1 93.4
18 10.6 114.2 122.1 93.5
16 12.7 109.6 118.1 92.7
15 7.6 116.4 124.2 93.7
16 10.9 106.7 118.1 90.3
20 16.1 106.2 112.3 94.6
18 12.7 107.8 113.9 94.6
Tl
TABLE OF TEST RESULTS
Field
Moisture
%drywt
Dry Denity
ib/cu ft
Maximum w Density
Ib/cu ft
Percent
Compaction Pamark
Reworked
Check on 115
l Backfill ofremoved area.
BENTON ENGINEERING. INC
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Proiect No. 69-IO-24D T2
La &to Greens
Test
No.
41
42
43
44
2
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
2
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
Approx- D.Ph imate of Fill
Location at Test
Lot No. in Feet
Field DV
Moisture Denily
%drywt Ib/cu ft
Maximum
b
Demity
Ib/cu ft
Percent
Compaction Rem&
2 14 13.3 108.8 118.0 92.2
1 17 13.6 107.7 113.9 94.6
2 16 13.5 109.9 118.0 93.1
3 18 13.3 109.8 118.0 93.0
2 18 9.5 118.5 124.2 95.4
3 20 12.2 115.1 122.1 94.3
2 20 9.4 116.2 124.2 93.6
3 22 12.2 112.8 122.1 92.3
1 19 8.6 115.1 124.2 92.6
3 24 10.7 114.0 124.2 91.8
2 22 14.2 107.2 112.3 95.5
2 24 13.3 105.8 112.3 94.2
3 26 12.1 108.2 113.9 95.1
9 10 11.1 106.8 118.0 90.6
8 10 11.9 110.5 118.0 93.7
10 8 10.0 112.5 122.1 92.2
3 27 11.9 109.8 118.0 93.1
4 22 13.7 110.8 118.0 94.0
1 22 12.2 113.0 117.4 96.3
2 25 14.9 108.7 113.9 95.5
1 23 21.1 101.8 110.6 92.1
1 25 14.5 110.3 118.0 93.6
2 26 14.9 105.3 113.9 92.6
1 27 15.2 106.4 113.9 93.5
2 28 16.5 105.4 112.3 93.8
2 30 15.5 106.8 113.9 93.8
3 28 15.6 109.8 118.0 93.1
2 32 11.8 111.8 122.1 91.6
1 29 14.2 108.9 118.0 92.3
2 34 12.2 103.0 113.9 90.5
1 31 11.6 112.0 122.1 91.8
2 38 12.8 109.7 118.1 92.9
4 24 14.7 101.2 112.0 90.3
4 26 14.7 106.8 112.3 95.0
4 28 14.8 106.9 113.9 93.8
5 20 12.9 107.9 118.0 91.4
4 30 11.1 110.0 122.1 90.1
7 10 13.6 108.0 118.0 91.6
8 6 15.4 104.5 112.3 93.0
8 8 15.3 112.2 118.0 95.1
TABLE OFTEST RESULTS (CONI)
BENTON ENOINEERING. INC
F'roiect No. 69-IO-24D T3
La haGreens
TABLE OF TESTRESULTS(CONT.)
Test
No.
81
82
83
84
85
86
EJ
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
IW
108
103
110
111
112
113
114
115
116
117
118
119
120
Approx- hPh imate of Fill
Location at Test
Lot No. inFeet
8
10
3
9
10
9
10
9
10
9
10
9
8
10
8
9
10
8
10
1:
10
10
10
l&2
10
162
3&4
566
10
10
1
10
6
7
10
10
10
10
9 a 10
10 12.6 106.7 118.0 90.5
8 12.0 109.1 119.0 91.7
20 11.3 111.5 122.1 91.4
8 14.8 105.2 112.7 93.5
10 16.9 104.4 112.7 92.7
10 15.1 116.7 122.1 95.5
12 14.3 104.9 112.7 93.2
12 14.5 108.4 118.0 91.9
14 17.2 108.4 118.0 91.9
14 11.1 106.8 118.0 90.6
18 10.2 109.3 118.0 92.7
18 13.0 lop.1 118.0 92.6
12 13.4 107.3 118.0 91.1
20 14.1 108.2 118.0 91.9
16 12.3 106.6 112.2 94.9
22 14.5 109.3 118.0 92.7
22 15.0 104.8 112.2 93.4
20 12.6 107.7 113.9 94.6
26 14.2 107.2 113.9 94.1
24 11.2 110.5 118.0 93.6
30 11.7 111.3 122.1 91.3
7 18.2 105.9 112.7 94.0
9 15.8 114.1 120.0 95.1
11 15.7 112.3 120.0 93.7
2 17.3 107.1 116.4 92.1
13 16.4 103.2 116.4 93.9
6 20.4 102.2 110.6 92.6
4 17.2 103.8 114.0 91.2
4 19.2 104.2 113.0 92.4
15 23.4 100.1 110.6 90.6
17 22.8 97.6 lW,l 91.1
31 19.9 100.1 110.6 90.6
19 24.3 100.1 110.6 90.6
20 15.0 106.8 117.0 91.3
20 22.4 97.3 1W.l 90.8
21 20.7 102.9 112.0 92.0
23 21.7 101.4 110.6 91.8
25 21.8 102.9 110.6 93.1
27 21.4 101.6 110.6 92.0
4 15.3 108.2 ,117.o 92.5
Fleid
Moisture
%drywt
Dry
Denity
Ib/cu ft
Maximum
Dr-Y
Density
ib/cu ft
Percent
Compaction Remsks
BENTON ENGINEER,NG. iNC.
Proiect No. 69-IO-24D
La Cwta Greens
T4
Test
No.
121
122
123
124
125
126
127
- 128
129
130
- 131
132
133
- !E
136
- 137
138
139
- 140
141
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Apprm- D.Pth
imate of Fill
Location at Test
Lot No. in Feet
10
6
1
7
8
9 d 10
7&8
2
3
182
384
586
788
9 a 10
4
5
6
7
8
9
10
29
10
33
11
14
:
39
30
lo?
8'
8*
8+
12 *
32
22
22
22
25
25
31
TABLE OFTESTRESULTS(CONT.)
Field bY
Moisture D.r.ity
% dry wt Ib/cu ft
Mauimum
BY Demity
ib/cu ft
Percent
Compaction ibmarks
22.0 100.6 110.6 91.0
19.6 101.6 112.0 90.7
21.5 101.8 110.6 92.1
14.4 107.2 113.3 94.6
20.0 103.7 113.3 91.5
14.4 111.2 121.0 92.0
12.6 110.6 121.0 91.5
11.9 112.4 122.1 92.2
16.8 113.0 121.0 93.4
15.2 112.3 121.0 93.0
15.9 108.2 116.4 93.0
17.8 104.0 113.3 91.8
13.9 109.2 118.0 92.7
15.1 109.9 118.0 93.2
14.6 113.2 120.0 94.5
15.9 111.8 116.4 96.1
14.1 114.6 122.1 93.8
15.4 112.1 120.0 93.5
13.9 112.8 121.0 93.3
16.3 108.5 116.4 93.2
12.8 114.t 122.1 93.5
l Finished Grade
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BENTON ENGINEERING. INC.
project No. 69-IO-24D
La Costa Greens
T5
LABORATORY TEST RESULTS
The maximum dry densities and optimum moisture contents of the maior fill moteriais o deter-
mined by the A.S.T.M. D 1557-66T method, that uses 25 blom of a 10 pound hammer faiiirg
from a height of 18 inches on each of 5 layers in a 4 inch diameter l/30 cubic foot compaction
cylinder, are presented as follows:
Soil Type
- Gray very fine to fim sandy clay
Dark gray very fin. sandy clay
Light greenish-gray clayey very flm to fim - sand with ciayston. chunks
Light greenish-gmy slightly clayey fine sand
Oiive-green silty clay - Gray brown slightly silty fine sand
Brown fin. sandy clay
Dark gray silty clay
Yellow-brown silty fim sand
Gray-black silty clay
Light brown silty fim sand
Maximum Optimum Mois-
Dry Dermlty ture Content
ib/cu ft % dry wt
115.8 9.8
119.9 12.2
124.2 11.2
122.1 11.5
110.6 15.7
113.9 13.3
117.4 13.1
110.5 16.3
116.0 13.2
118.0 13.6
103.6 15.5
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BENTON ENGINEERING. INC.
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5Ge i 67 i ’ c 2,9 ‘&,r
,z /- 2 I7 GiccC~;c
i ;1 \ J 6 *.- _ ,~, , -
/ A -i ,,..“,a- , ,,? ,,, :
ti: \ . . $- I. ;+-. 0 ‘; c LC -
./ i ,,& ,. ,‘A- ” ; ,‘? , rz.5 -
I--3. cc3 % *r’ 2: L1 + :- I’ , ..” .’ ;.--,y ~, -/
__.~-~-,~-
-5, 0.~;
“i’ ~+. .;” .,1.
-3 3 ,’
,j /,$ ; >/53~JC
SLOPE STABILITY ANALYSIS
LA COSTA GREENS
:SAN DIEGO COUNTY, CALIFORNIA
PROJECT NO.
69- lo-24D i BENTON ENGINEERING, INC. DRAWING NO.
2
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PHILIP HENI(IHG BENTON PIIEIIIDENT CIYIL ENGIWIZI”
BENTON ENGINEERING, INC.
APPLIED *OIL MECHANICS - FOUNDATION6
6741 EL CAJON BOULEYARD *AN DIEGO. CALIFORNIA 02115
June 25, 1970 SAN DIL.z.2: ,w-se*. L* ML**: 46WS8S4
Ranch0 La Costa, Inc.
Routs 1, Box 2550
Encinitco, California 92824
Subiect: Project No. 69 -lO-24D
Report of Results of pH and
Soil Resistivity Tests
La Costa Greens
North of La Costa Avenue
East of El Camino Real
San Diego County, California
Permit No. L5673
Gentlemen:
This is to repcrt the results of a soil reslstlvlty test and a pH test of the most active soils likely
to come in contact with the culvert pipe on subject project. These tests were performed in
accordonce with Test Method No. Califomla 643-B, Part III and Port IV of the California
Division of Highways Materials Marual.
The pH of the soil was determined to be 5.3 and the minimum resistivity WOI 375 ohms. Accord-
ing to the Chart for Estimating Yean to Perforation of Metal Culverts, these data indicate a
useful life of approximately three years for 16 gcuge corrugated metal pipe.
In order to meet the 25 year life required by the County of San Diego, It is recommended that
the minimum wail thickness of corrugated metal pipe imtolled on subject proiect be 12 gauge
and that this pipe be treated with an asbestos bonded bituminous coatlrrg and paved invert o
indicated In Table 7-821.6A of Part 7 of the California Division of Hlghvmys Plannirg Manual,
This treatment will add 20 yean to the life of the pipes carrylrg abrasive materials at flow
velocities not exceedlrg 7 feet per second and for culvert pipes carryirg non-abralve materials
at flow velocities greater than 7 feet per second. This treatment coupled with the odded life
anticipated from 12 gauge pipe rather than 16 gwge pipe will meet the minimum required life
expectancy of 25 years.
Respectfully submitted,
BENTON ENGINEERING, INC. -
. ..Q&cL
Willlam G. Catlin, Civil Eglneer
Distr: (3) Addressee
(2) Mr. B. L. Kmmer
(3) Rick Ergimerlrg Company
( 1) Robert W. Radgen