HomeMy WebLinkAbout; Dam Site Adjacent to Mt. Hinton; Dam Site Adjacent to Mt. Hinton; 1960-08-12SOILS INVESTIGATION
Proposed Dam Site
Adjacent1 to Mt. Hinton
San Diego County, California
for the
Carlsbad Municipal Water District
Boyle Engineering
Engineers
Project No. 60-6-8AF
August 12, 1960
BENTON ENGINEERING, INC.
4342 Fairmount Avenue
San Diego 5, California
SOILS INVESTIGATION
Objectives
The objectives of this investigation were to determine the existing subsurface conditions
along the axis of a proposed dam to be constructed adjacent to Mt. Hinton, east of Carlsbad,
California and also investigate possible sources of borrow material for earth fill. In order to
accomplish these objectives, field explorations were made at three locations along the proposed
axis of the dam and at ten possible borrow sources northeast of the dam axis. Laboratory tests
were performed on representative samples of the proposed borrow material in order to classify
the soils and to determine the physical characteristics of the soils when compacted.
Field Investigation
Three borings were drilled along the axis of the dam using a rotary diamond coring drill
rig and continuous core recovery was attempted. However, in the more weathered zones little
recovery was possible. The samples recovered have been stored in our laboratory. The depths
of these borings varied from 73.8 to 80 feet below the existing ground surface. The ten borings
in the proposed borrow areas were drilled to depths varying from 2.2 to 10 feet with a truck-
mounted rotary bucket-type drill rig. Loose representative bag samples were obtained of the
soils encountered in Boring IB to 6B, inclusive, and undisturbed samples were obtained at
frequent intervals in the soils ahead of the drilling in Borings 1C to 4C, inclusive. Also,
representative loose samples were obtained in Borings 1C to 4C, inclusive. The drop weight
used for driving the sampling tube into the soils was the "Kelly" bar of the drill rig which weighs
1360 pounds, and the average drop was 12 inches. The driving energy required to force the
sampling tube through one foot of soil is shown on Drawing No. 13.
-2-
The approximate locations of the exploration borings are shown on Drawing No. 1, entitled,
"Location of Test Borings". Acontinuous log of the soils and rock formations encountered in the
borings was recorded at the time of drilling and is shown on Drawing Nos. 2 to 13, inclusive,
each entitled, "Summary Sheet".
The soils were visually classified 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.
Field pressure tests were performed at various depths in Borings 1A, 2A, and 3A.
Laboratory Tests
Laboratory tests were performed on three representative samples of the proposed borrow
materials in order to classify, establish compaction criteria and to determine the permeability,
internal angle of friction and cohesion of the compacted soils. A permeability test was also
performed on an undisturbed sample obtained at a depth of 2 feet in Boring 1C.
TEST PROCEDURES AND RESULTS
Compaction Tests
Compaction tests were performed on three representative samples of the proposed borrow soils
to establish compaction criteria. The soils were tested according too modified A.S.T.M. D-698
method of compaction which uses 26 blows of a 10 pound hammer dropping 18 inches on each
of 3 layers in a 4 inch diameter l/30th cubic foot mold. The results of the tests are presented below:
Boring Depth
Number in Feet
2C
4B
5B
2-4
1-2
4-5
Maximum
Soil Dry Density
Description Ib/cu ft
Slightly silty fine to coarse sand
Clayey fine to medium sand
Slightly clayey fine to coarse sand
127.1
122.0
126.0
Optimum
Moisture Content
% dry wt
9.0
12.1
8.9
Note: all soil types are of "granitic" origin
-3-
Triaxiol Shear Tests
Triaxial shear tests were performed on the three representative samples of the proposed
borrow soils remolded at optimum moisture to 90 percent of the maximum dry density. The
samples were allowed to become saturated by imposing a pressure head of water of approximately
one half of the surcharge pressure. After the sample was saturated, the saturation pressure was
removed and the sample was allowed to stand 24 hours. The triaxial test was run in approximately
15 minutes without permitting sample drainage. A representative moisture content was obtained
after testing.
Deviator stress versus strain curves were plotted for each test, and the devlator stress
at 12 1/2 percent strain was picked for the ultimate stress. Mohr circle diagrams were plotted
for each test to form a shear envelope. The plotted Mohr circles and shear envelopes are shown
on Drawing Nos. 14,15, and 16, entitled "Shear Strength Remolded Soils". A correction of
minus 200 pound per square foot should be applied to the cohesion shown on the drawings. This
correction is due to a calibrated resistance in the testing apparatus. The internal angle of friction
and corrected cohesion for the compacted soil samples are presented below:
Boring 2C Boring 4B Boring 5B
Depth 2'-4' Depth 1'-2' Depth 4'-5'
Internal angle of friction 30 1/2° 26° 32°
Cohesion (pounds per sq. ft.) 500 400 500
Grain-Size Analysis
Tests were performed on four representative samples of the proposed borrow soils to
determine the amount and size of the soil particles. The tests were performed in accordance
with the procedures outlined in A. S.T. M. D422-54T with some modifications. A sieve analysis
of the sample obtained between depths of 1 and 3 feet in Boring 4C indicated this soil to be
-4-
similar to the soil between depths of 4 and 5 feet in Boring 5B, therefore, hydrometer tests, to
determine the percentage of silt and clay, were not performed on this sample. The results of the
mechanical analyses are presented in graphical form on Drawing No. 17.
Atterberg Limit Tests
Atterberg Limit Tests were performed on the material passing the No. 40 sieve in accordance
with the procedures outlined in A.S.T.M. D423-54T and A.S.T.M. D424-54T. The results of
these tests are as follows:
Liquid Limit
Plasticity Index
Permeability Tests
Boring 2C
Depth 2 '-4'
Less than 25
Non-Plastic
Boring 4B
Depth T-21
25.6
7.6
Boring 5B
Depth 4' -5'
Less than 25
Non-Plastic
A constant head test was performed on the soil sample from Boring 2C at a depth of 2 to 4 feet
and falling head tests were performed on three other representative soil samples. Samples from
Borings 2C, 4B, and 5B were remolded in a 4 inch diameter 1/30 cubic foot permeameter cylinder
to 90 percent of the maximum dry density and a one inch high undisturbed sample obtained at a
depth of 2 feet in Boring 1C was tested within a 2.5 inch O. D. brass liner ring.
The head differential in the constant head test was 52 3/4 inches. The heights of head above
the bottom of samples in the falling head tests were as follows:
Boring
Number
4B
5B
1C
Depth
in Feet
1-2
4-5
1.5-2.0
Trial
1
2
1
2
1
2
Height at Start
of Test in Inches
71 1/8
71 1/8
71 1/8
71 1/8
493/4
49 3/4
Height at Ei
of Test in Ir
50 1/4
50 1/4
50 1/4
50 1/2
44 1/4
44 1/4
The calculated coefficients of permeability, corrected to a temperature of 20° Centigrade,
are presented on the following page.
-5-
V.
Coefficient of
Boring
Number
2C
4B
5B
1C
Depth
in Feet
2-4
1-2
4-5
2.0-2.5
Type of
Sample
Remolded
Remolded
Remolded
Undisturbed
Trial
1
2
1
2
1
2
1
2
Type of
Test
Constant Head
Fall ing Head
Falling Head
Falling Head
Permeability
cm/sec .
2.38x 10";?
1.64x 10"5
2.00x 10";?
1.84x 10"°
4.49x 10"5
7. 15 x ID'6
1.04x10"
7.82 x 10"°
Field Pressure Tests
Field pressure tests were performed at various depths in Borings 1A, 2A and 3A under a
hydrostatic head of 50 psi at the ground surface. A round rubber seal which expanded when a
vertical load was applied to the top of it by the drill stem was used in sealing the borings at
various depths. It should be noted that during some of the tests water apparently either by-passed
the seal or flowed through the fractured zones adjacent to the seal.The results of the tests and
observations were as follows:
Boring
Number
1A
2A
3A
Depth of Seal Below
Surface in Feet
67.6
57.6
49.5
39.5
19.5
61
50.5
49
39.5
29.5
19.5
9.5
Water Loss in
Cubic Feet Remarks
5.2 C.F. in 10 min. Water flowed out top of hole
6.7 C.F. in 10 min. Water flowed out top of hole 5 min.
after start of test
1.0 C.F. in 4 min. No water flowed out top of hole
4.3 C.F. in 4 min. Water flowed out top of hole 3 min.
after start of test
4.0 C.F. in 4 min. No water flowed out top of hole
—- No water loss
No water loss
-— No water loss
4.3 C.F. in 3 min. Water flowed out top of hole
4.0 C.F. in 3 min. Water flowed out top of hole
2.6 C.F. in 7 min. No water flowed out top of hole
5.6 C.F. in 3 min. Water flowed out top of hole
Should any question arise concerning the testing procedures or the interpretation of the test data/
please feel free to contact us.
Respectfully submitted/
BENTON ENGINEERING/ INC.*^S;/AL^—
Reviewed v~Ph~TTTp
BENTON ENGINEERING, INC,
APPLIED SOIL MECHANICS - FOUNDATIONS
PHILIP HENKING BENTON, PREB.
CIVIL ENGINEER APPENDIX A.
Unified Soil Classification Chart*
4342 FAIRMOUNT AVENUE
SAN DIEOO 5, CALIFORNIA
ATWATEH 1-S5B1
SOU. DESCRIPTION
I. COARSE GRAINED. More than half of
material is larger than No. 200
sieve size.**
GRAVELS CLEAN GRAVELS
More than half of ^Little or no fines)
coarse fraction is
larger than No. U
sieve size but smaller
than 1 inches. GRAVELS WITH PINES
(Appreciable amount
of fines)
SANDS CLEAN SANDS
More than half of (Little or no fines)
coarse fraction is
smaller than No. A
sieve size.
SANDS WITH FINES
(Appreciable amount
of fines)
II. FINE GRAINED. More than half of
material is smaller than No. 200
sieve size.**
SILTS AND CLAYS
Liquid Limit
Less than 50
SILTS AND CLAYS
Liquid Limit
Greater than 50
GROUP TYPICAL
SYMBOL NAMES
GW Well graded gravels, gravel-sand
mixtures, little or no fines.
GP Poorly graded gravels, gravel-sand
mixtures, little or no fines.
CM Silty gravels, poorly graded gravel-
sand-silt mixtures.
GC Clayey gravels, poorly graded
gravel-sand-clay mixtures.
SW Well graded sand, gravelly sands,
little or no fines.
SP Poorly graded sands, gravelly
sands, little or no fines.
SM Silty sands, poorly graded sand-
clay mixtures.
PC Clayey sands, poorly graded sand-
clay mixtures.
ML Inorganic silts and very fine sands,
rock flour, sandy silt or clayey-silt-
sand mixtures with slight plasticity.
CL Inorganic clays of low to medium
plasticity, gravelly clays, sandy
clays, silty clays, lean clays.
OL Organic silts and organic silty-clays
of low plasticity.
MR Inorganic silts, micaceous or
diatomaceous fine sandy or silty
soils, elastic silts*
CH Inorganic clays of high plasticity,
fat clays
OR Organic clays of medium to high
plasticity.
PT Peat and other highly organic soils.HIGHLY ORGANIC SOILS
*Adopted by the Corps of Engineers and Bureau of Reclamation in January, 1952.
**A11 sieve sizes on this chart are U. S. Standard.
BENTON ENGINEERING, INC.
APPLIED SOIL MECHANICS - FOUNDATIONS
4342 FAIRMOUNT AVENUE
PHILIP HENKING BENTON, PRES. SAN DIEGO 5, CALIFORNIA
CIVIL ENGINEER APPENDIX B_ ATWATER 1-5581
Description of Sampling and Laboratory Testing Procedures
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 2.50 inches
inside diameter, with a special cutting tip on one end and a double ball valve on
the other, and with a lining of thin brass rings, each one inch long. The sampler
is 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 moisture 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 shear machine of the strain control
type in which the rate of deformation is approximately 0.1 inches 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 secured. Each sample is sheared under a
normal load equivalent to the weight of the soil above the point of sampling. In
some instances, samples are 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 tests 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 on the sample until the rate of deformation is
equal to or less than 1/10000 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 stops. The dial reading is recorded and expansion is
recorded until the rate of upward movement is less than 1AOOOO inch per hour*
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SUMMARY SHEET
BORING NO; 1A
Relative Fl FV 45' Above 3A
CORE RECOVERY 1 COLOR
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DESCRIPTION
^memmmmm
Non*
/5" Froaments
None
3" Fraflmenh
7" Core and Fraflmenh
14" Core
10" Cera
None
BROWN
GRAY BROWN
GRAY BLUE
GRAY BROWN
DECOMPOSED GRANITE
(VERY FIRM)
GRANITE BOULDER
(HARD)
DECOMPOSED GRANITE
(VERY FIRM)
T^A/* BENTON ENGINEERING ORAW^G N0
P-18668 CONTINUED ON DRAWING NO. 3
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66 SAMPLENUMBERSUMMARY SHEET
1ABORING N0.__
El EV,
CONTINUED FROM DRAWING NO. 2
None
^1/2" Core
9" Core
None
8" Core and Fragments
None
19" Core and Fragments
24" Core
18" Core and Fragment*
GRAY BROWN
BROWN
GRAY BROWN
GRAY AND PINK
GRAY
nRAY Bl 1 IP
» H- 5 .. t £ «E
1" i » Sd -o:i 5s s- 52^^ * q o > 4 u^f
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DECOMPOSED GRANITE
(VERY FIRM)
(At 55'9" Lost Circulation.
Added Aquajel With 350 Gallon!
of Water.)
GRANITE (HARD)
PROJECT NO. QCM-rriM CMriKIC-CTDIMr DRAWIN6NO.60-6-8AF BENTON ENGINEERING 3
CONTINUED ON DRAWING NO. 4
0. HI
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SUMMARY
BORING NO..
ELEV
SHEET
1A
CONTINUED FROM DRAWING NO. 3 § t
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ssi
60
70
72
74
76
78
20" Core and Fragments (Note; At 66*6" Lost Circulation
Bit Dropped 2", Added
26" Core end Fragments 350 Gallons and Aquajel)
GRAY BLUE GRANITE (HARD)
4" Cere
7'-7 1/2" Core ond
Fragments
Notes; Total water used between various depths is presented below:
Oto5Q'-0"350 gallons
0£
I
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CO
50'-0" to 55'-9"100 gallons
55'-9" to 56'-6"350 gallons plus aquajel
56'-6" to 66'-6"350 gallons plus aquaiel
66^6" to 70'-5"350 gallons plus aquajel
Cased hole to 70'-9" Used no water for 1 1/2" core between
7Q'-9" and 78'-6"
PROJECT NO.
60-6-8AF BENTON ENGINEERING DRAWING NO.
4
CARLSBAD MUNICIPAL WATER DISTRICTX
z
ft. klhi iiia u.SAMPLENUMBERSUMMARY SHEET
BORING NO. 2 A
Relativepipv 62.5' Above 3A
CORE RECOVERY COLOR
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1 £ 1 * 8 d Sj5 g Sfc uoK^«
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DESCRIPTION
0£.
1AIU
10l£
1 Z16
ISlo
2
26
28
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32
None
15" Core
None
2' -6" Core
T-6" Core
None
10" Core and Fragments
GRAY BROWN
GRAY BLUE
BROWN
DECOMPOSED GRANITE
(VERY FIRM)
GRANITE BOULDER(HARfiT
DFCOMPOSED GRANITE
(VERY FIRM)
(Note: 1 O«inO ?nm« wnter
at 32')
PROJECT NO. C Kl ri M C C D 1 M r DRAWING NO.60-6-8AF BENTON ENGINEERING 5
['•1866K CONTINUED ON DRAWING NO. 6
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68 SAMPLENUMBERSUMMARY SHEET
BORING NO.-2A
El EV
CONTINUED FROM DRAWING NO. 5
Frwnm»nt<
2* Core and Fragments
None
26" Core and Fragments
34" Core and Fragments
None
Core Fragments
14" Core and Fragments
3'-4" Core
(100% Recovery)
15" Core
None
8" Core
3'-8" Core and
Fragments
3'-6" Core and
Fragments
BROWN
GRAY
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DECOMPOSED GRANITE
(VERY HARD)
GRANITE (HARD)
DECOMPOSED GRANITE
(VERY FIRM)
PROJECT NO. QC-MTAM C M P 1 MET C D 1 MP DRAWING NO.60-6-8AF BENTON ENGINEERING 6
I'- 186ft8 CONTINUED ON DRAWING NO. 7
H »-a. ww wo u.
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SUMMARY SHEET
BORING NO._2A_
ELEV
CONTINUED FROM DRAWING NO. 6
wIt
£2
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70 3'-651 Core and
_ Fragments
72
74
GRAY_DECOMPOSED GRANITE
(VERY FIRM)
76-
3' -10" Core and
Fragments
GRANITE (HARD)
80-
GRAY BLUE
UJ
H-
Note; Total water used between various depth is presented below:
700 gallons
73' to 80'No Loss
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60-6-8AF BENTON ENGINEERING DRAWING NO.
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3?SAMPLENUMBERSUMMARY SHEET
BORING "" 3A
El EV
CORE RECOVERY COLOR
Non*
14" Core and Fragments
15" Core and Fragments
26" Core and Fragments
12" Core and Fragments
8" Core and Fragments
5" Co*"6 and Fragments
JJGHI GRAY
BROWN
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DESCRIPTION
DECOAAPOSED GRANITE
(VERY FIRM)
(Note: At 11' was first "plu.q"
clayey cuttings. Enough clayey
material to keep water muddy
between 12' and 17'.)
(Note: At 27' enough clayey
material to keep water thickenec
Used little water. Cutting from
27' to 44' clqyey fine to
medium sand.)
PROJECT NO. DRAWING NO.60-6-8AF BENTON ENGINEERING 8
P- 1866H CONTINUED ON DRAV/ING NO. 9
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66 SAMPLENUMBERSUMMARY SHEET
BORING NO. 3A
Fi FV,
CONT. FROM DRAWING NO. 8
5" Core and Fragments
None
6" Core and Fragments
5" Core
17" Core and Fragments
20" Core and Fragments
20" Core and Fragments
26" Core and Fragments
GRAY
GRAY BLUE
i H- 5 .. t £ *,£K u. ^H — • 0"^
| ^ £ » fi 3 Z0
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DECOMPOSED GRANITE
(VERY FIRM)
(Note: At 43' water became
to thick with clay, therefore.
water had to be changed.)
(Note: Between 54 and 55 feet
water thickening with clay.)
GRANITE (HARD)
PROJECT NO. DC-MTnM C M n MET CD 1 Mr DRAWING NO.60-6-8AF BENTON ENGINEERING 9
I'- 18668 CONTINUED ON DRAWING NO. 10
a. ww uo u.
SUMMARY SHEET
BORING NO.3A
ELEV.
CONTINUED FROM DRAWING NO. 9
g>
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i £
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fc £
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68
70
72
" Core gtxJ Frogments GRAY BLUE GRANITE fHARDl
8" Core ond Fragments
U
"5.*-to
Nofe: Tofal Wafer Used Between Various Depfhs:
Oto44'
44' to 74'
200 gallons
No loss
a.
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1
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PROJECT NO.
60-6-8AF BENTON ENGINEERING DRAWING NO.
10
1'- 18668
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SUMMARY SHEET
BORING NO. IB
EI.FV,
Brown, Slightly Molst^
Medium Firm
Dark Brown
Light Brown to Light
Gray Brown
Very Firm
:INE SANDY CLAY
FINE TO COARSE
SAND
(DECOMPOSED
GRANITE)VE ENER6YKIPS/FT.S Hu.
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t #
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>• «K «O -I SHEAR 1RESISTANCEKIPS /SO. FT.n BORING NO. 2Bu
2
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^[yT
Brown to Dark Brown,
MoUt, Medium Firm,
3% to 10% Granite
Froflmcntsbark Srown, Moist,
\ AnAflf IN** l*irrn f^rfiinlt'C*
\ Fragments
FINE TO SANDY
CLAY
fJffWPcf^RSE
fo.c;.}
BORING NO. 3B0
2
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. * • *T * .*».'»j'h'
Light Brown to Yellow
Brown, Slightly Moist,firm
V/^il B_ Cl*—l il, Yellow Brown, Slightly
\/Vbist, Very Firm
FINE SANDY CLAV
(DECOMPU5fcD
GRANITE)
FINE TO COARSE
DECOMPOSED GR/NITE
BORING NO. 48
o£. — |
A
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£T>
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Lignr sea D'own, ^ngnriy
Moisl-, Mec ium Firm
Light Brown to Lfpht Gray
Brown, Slightly Moist,
Firm
FINE SANDY CLAY
CLAYEY FINE TO
MEDIUM SAND
MERGES TO A
DECOMPOSED
GRANITE
P^!FN° BENTON ENGINEERING DRAWING NO.
11
O b.< =>(A Z
SUMMARY SHEET
BORING NO._J[§—« c
§
|3
S5
5£Light Brown, Slightly CLAYEY FINE TO
Moist, Medium Firm COARSE SAND
MERGES TOD jj, L 0 c,Reddish Brawn, Firm
GRANITE
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BORING NO.
T-
1 £
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Dork Reddish Brown,
Slightly Moist, Firm
FINE SANDY CLAY
MERGES TO ADECOMPOSED GR>MITF
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BENTON ENGINEERING DRAWING NO.
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BORING NO
SHEET
1C
pray Brown, Dry,
Very Firm DECOMPOSED
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36.9"FIELD MOISTURE% DRY WT.2 ouj Oa ^
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BORING NO. 2C
Dry, Very Firm
SLIGHTLY SILTY
FINE TO COARSE
SAND
(ALLUVIAL)
DFPO MPO<\ F n
GRANITE
4.0
41,0
79.2
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BORING NO. 3C
Light Brown. Hrv. 1 twa*
ijght Brown, Dry
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Very Firm
Slightly Moist
DECOMPOsFD
GRANITE
ALLUVIAL D.G.
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Light Gray Brown, Dry
Slightly Moist, Very Firm
DECOMPOSED
GRANITE
50.6
54.6
PR°0EJ™F°'BENTON ENGINEERING DRAWING NO.
13
5X5 TO THE '/J INCH 359-6
trength Remolded So
/-.^~ 5 X 5 TO THE Vt INCH 359-6
\Vc^ •- F i • •- r E L t L S -C-. '•' C O ' ' >•..,.-..=,.
oso
CA U.SBAO WATER EXSTiUGT
I Shecfrr Strenjgth Rerpolded Soils
Dam iite Ad acent;o Mt. IHinton
Bqrinfi4B
Average/
Bqg
ompac
loislxm
Depfh I* ^
dens if)
it 16. i percdnt
ed dry
rorate
110). 9 pourds per cubic: f&pt
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rn
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C =600
2n
.-ii. %
Stress" in Kip:per irerp
fV^ 5 x s TO THE '/2 INCH 359-6
CARLSBAD WATER plSTRfilTO
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Average t
Avjerage T l
xxnpac
Shear iSirength Remolded Sotls
Dep
ecf dry densir)
cbrTreiit =14
6am Sire Adjacent to
h4' -
' = 113.3 pourds per cubic
percfenF
Mt. Hmron
Zmm~7O~
Zo
<t>= 32
s
S
-n"a3 7g1
\\-
Normil Stress in Ki w per !<^oare :«ot
CARLSBAD MUNICIPAL WATER DISTRICT
U. S. Standard Sieve Series
2DO 100 60 40 30 10
^Boring 4B
Depth l'-2'"
B<pf|n
i Depth
Particle Siz$ in mm.; •
PARTICLE-SIZE DISTRIBUTION
Project No.
60-6-8AF BENTON ENGINEERING, INC.
Drawing No.
17