1991-2722 G
Street Address
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Category
I
3c2~ ?>o
Serial # .
9- 1-&~ Cq
Name
I
Description
Year
Plan ck. #
recdescv
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( ;:: ILL "'L 7 L L-G(L
, DENNIS E. ZIMMERMAN - n \\f7 R lID
GEOTECHNICAL ENGINEER œ Œ Œ .Œ U \!J l!; n
CIVIL ENGINEER U
1942 Abbe Street SEP 2 7 1991
San Diego, California 92111
(619) 277-3383 CITY OF ENCINITAS
DEPT. OF PUBLIC WORKS
.'
I
ENGINEERING DEPT.
=
February 201 1991-
Ms. Georgia D. Griffiths
2207 Sereno View Lane
Encinitasl CA 92024
Project:
Job No. 91-01-07
Existing Cut Slope
2207 Sereno View Lane
Encinitas, CA 92024
I inspected the recently cut slope situated northwest of
the proposed horse arena on February 18,1991.
A representative
soil sample was obtained from the face of the slope and returned
to the laboratory for testing and analysis.
The. soil in the cut
bank was a light brown silty fine sand with discontinuous
layers of orangish light brown silty fine sand to approximately
one inch in thickness dipping out to slope (toward the east)
about one to two degrees.
A direct shear test was performed on
a sample remolded to 95 percent of maximum density.
Test
results are shown in Table I, below:
TABLE I
DIRECT SHEAR
Aooarent Cohesion
.. 725 psf
Apparent Angle of Internal Friction
34 degrees
MAXIMUM DRY DENSITY & OPTIMUM MOISTURE CONTENT
Maximum Dry Density
121.3 pcf
Optimum Moisture Content
9.5%
'.,. .
.~ Georgia D. Griffit.11S
2/20/91
page 2
I performed a slope stability analysis by the Janbu Design
... Method (Harvard Series) using the labor§!tory test results above
and the following parameters:
Slope Ratio: l.5: 1.0 (horizontal: vertical units)
Slope Height: 19 feet
No seepage forces
The factor of safety exceeds l.S.
Therefore, it. is my
opinion that the existing cut slope is stable against
deep-seated rotational failure.
Slopes with a maximum slope
inclination of 1.5 to 1.0 (horizontal to vertical units) may be
cut into undisturbed soil to a maximum height of 30 feet.
Proper drainage devices should be installed in order to preven
water from running over the top of the slope.
~f~~bmi~ed'
~~:~26676
GE 928
Distribution: (3) Addressee
J
.
't
ohn B. i!ox - P.E.
tephen D. Dillemuth - P.E.
ardon L McElroy. P.LS.
SAN DIEGUITO ENGINEERING, INC.
4407 MANCHESTER, SUITE 105
ENCINITAS. CA 92024
(619) 753-5525
FAX (619) 943-8236
SDE 3935
January 6, 1992
Ms. Georgia Griffiths
2207 Sereno View Lane
Olivenhain CA 92024
2722 G
HYDROLOGY ANALYSIS
CIVIL ENGINEERING
PLANNING
SURVEYING
òtC
?fr
/- 2,l-or~
ANALYSIS BASED ON RATIONAL METHOD
Q=C (i) A where C = Coefficient
i = Intensity
A = Area
Area
= 3.8 ac.
Coefficient
= 0.45
Intensity
in/hr
= 4.0
Therefore Q
= 0.45 (4.0)
3.8
= 6.8 c.f.s.
X1307
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0 ïDGÐ::~. (
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1697 E
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1000
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, SCALE I: 2400
400 600 800
200 0 200
61.11A1 ,1/11£/9 =3.1¡f~"é5' r-J""'-.""'-- CO NTOUR INJERVAL 5 FEET
u. s. c. a G. S. SEA LEVEL DATUM OF 1929
TWO THOUSAND. FOOT CALIFORNIA RECTANGULAR GRID (ZONE VI)
THE LAST THREE DIGITS OF THE GRID NUMBERS ARE OMITTED
RECTANGULAR COORDINATE VALUES ARE SHOWN ON THE SOUTH AND WEST MAR(;7INS
THE GEOGRAPHIC VALUES ARE SHOW
1
.-
H' -.-
, "
"
TABLE 2 (
RUNOFF COEFFICIENTS (RATIONAL METHOD)
" -'
L. .
DEVELOPED AREAS (URBAN)
Coefficient....£
Soi I (ìr.~ {l)
Land Use
A B C D
Res i dent i a I :
Sing J e F am i I y .40 .45 .50 .55
Multi-Units .45 .50 .60 .70
Mob i I e homes .45 .50 .55 .65
Rural (lots greater than 1/2 acre) .30 .35 .40 @
Corrrnerc i a I (2) .70 .75 .80 .85
80% Impervious
Industri aJ (2) .80 .85 .90 .95
90% Impervious
. ,
, i
NOTES:
(I)Soil Group måps are available a~ the 'offices of the Department of Public Works.
(2)Where actual conditions deviate significantly from the tabulated impervious-
ness values of 80% or 90%, the values given for coefficient C. may be revised
by multiplying 80% or 90% by the ratio of actual imperviousness to the
tabulated imperviousness. However, in no case shall the final coefficient
be less than 0.50. For example: Consider commercial property on D soil~group.
Actual imperviousness
- 50%
I
I .
Tabulated imperviousness = 8~~
Revised C . 50 x 0.85 = 0.53
80
c = ,.J. f)"
IV-A-9
APPENDIX IX-B
Rev. S/81
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SAN DIEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
DES I GN MANUAL
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FOR NATURAL WATERSHEDS
DATE /2/I/G J APPENDIX X-A
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JNTENSITY"DUMnON OrSIGN CHART
.1-
.
rc..::lz,BMinutes I
nllt'i\ ti nn
Hou rs
.)
Directions for Application:
1) From precipitation Maps determine 6 hr. and
24 hr. amounts for the selected frequency I
These maps are printed in the County Hydrology
Manual (10, 50 And 100 yr. maps included in the
Design and Procedure Manua1),
2) Adjust 6 hr. precipitation (if necessary) so
that it is within the range of 45% to 65t of
the 24 hr. precipitation. (Not nrrlicable
to Desert)
3) Plot 6 hr. precipitation on the right side
of the chart.
4) Draw a line through the point parallel to the
plotted lines.
5) This line is the intensity-duration curve for
the location being analyzed.
Application Form:
0) Sel ected Frequency /tltJ yr.
1) P6 D Z, ?'J-in.. P24D ,f, 7 , *P6 I:
. . P24
2) Adjusted *P6= 0 ~, ~~ in.
3) t a / Z , 8 min.
c
4) I D ~ 0 in/hr.
*Not Applicable to Desert Region
5"8 %*
.1.
Revised 1/85
",-
-.
PROJECT:
Griffiths 2722G
INVERT WIDTH (feet) ...
LOPE (feet/foot) .....
EFT SIDE
LOPE (X to 1) ........
EPTH (feet) . ... ......
ELOCITY (fps) ........
EA (square feet) ....
DEPTH ........
VELOCITY. . . . .
TRIANGULAR CHANNEL
DATE: 12-27-1991
TIME: 14:35:52
0.00
.0100
2.00
0.77
3.78
1. 80
0.80
3.58
MANNINGS n .........
.020
6.80
Q (cfs) ............
RIGHT SIDE
SLOPE (X to 1) .....
TOP WIDTH (feet) ...
4.00
4.64
VEL. HEAD (feet) ...
P + M (pounds) .....
0.22
79
CRITICAL SLOPE .....
0.0086
FROUDE NUMBER ......
1.07