HomeMy WebLinkAboutCT 73-49; Arco AM-PM Mini Market; Drainage Study; 1992-05-12HYDROLOGY AND DRAINAGE STUDY
FOR
ARC0 AM-PM MINI-MARKET
C.U.P. 91-3
TABLE OF CONTENTS
SHEET 2 ...................... SITE CONDITIONS & DRAINAGE CHARACTERISTICS
SHEET 3 ...................... DESIGN DATA & METHODS
SHEET 465 ................... DRAINAGE CALCULATIONS
APPENDIX I ................... CHARTS & GRAPHS
APPENDIX II .................. HYDROLOGY PLANS
SHEET 1
SITE CONDITIONS:
EXISTING CONDITIONS CONSIST OF AN IMPROVED LOT FORMERLY OCCUPIED
BY THE BANK OF SAN DIEGO WITH PAVED AND LANDSCAPED AREAS. SEE CITY
DRAWING 228-5 FOR REFERENCE GRADING AND IMPROVEMENT PLANS. NO
OFF-SITE AREAS DRAIN ONTO OR ACROSS THE EXISTING'AREAS TO BE
REGRADED AND IMPROVED.
DRAINAGE CHARACTERISTICS:
RUNOFF WILL BE LIMITED TO SHEET FLOW FROM LANDSCAPED SLOPES AND
PAVED AREAS WITH BUILDING ROOF AREAS DISCHARGING ONTO PAVED AREAS
THROUGH CURB OUTLETS OR ONTO SPLASH BLOCKS IN LANDSCAPED AREAS
AND COLLECTED BY SURFACE DRAINAGE SWALES, EXCEPT FOR PUMP ISLAND
CANOPY, WHICH WILL BE DRAINED THROUGH UNDERGROUND PIPES. RUNOFF
WILL BE CONTROLLED BY SURFACE IMPROVEMENTS CONSISTING OF CONCRETE
CURBS AN0 GUTTERS, AND CONCRETE SWALES DIRECTING FLOW TO POINTS
OF DISCHARGE AT EXISTING DRAINAGE FACILITIES OR TO NEW SUB-SURFACE
SYSTEMS.
SHEET 2
DESIGN DATA & METHODS
DESIGN BASE0 UPON THE SAN Dl EGO COUNTY FLOOD CONTROL DESIGN 8 PROCEDURE
MANUAL
DATA USED:
1.
2.
3.
4.
5.
SOIL TYPE FOR NON PAVED AREAS - GROUP C
RUNOFF COEFFICIENTS FROM APPENDIX I-X
LANDSCAPED AREA 0.40
ROOF & PAVE0 AREA 0.90 - CONSERVATIVE SINCE TOTAL IMPERVIOUS
AREA 90% USE 0.90
TIME OF CONCENTRATION.TI FROM URBAN AREA FLOW CURVES APPENDIX X-C FOR
SHEET FLOW; VELOCITY FOR GUTTER FLOW FROM APPENDIX X-D; VELOCITY FOR
CONCRETE SWALES FROM MANNING'S EQUATION FOR OPEN CHANNELS; VELOCITY
FOR PIPE FLOW FROM MANNING'S EQUATION.
Tc = Ti + Tf
TI (OVERLAND FLOW TIME OR INLET TIME)
Tf (TRAVEL TIME IN GUTTER, SWALE OR PIPE)
EXAMPLE OF CALCULATION PROCEDURE FOR Tc DETERMINATION
INITIAL SOAKING TIME - 5 MlN. (CITY OF CARLSBAD)
USE 5 MIN.
"C" FACTOR OF DRAINAGE AREA A-I - 0,40
DISTANCE FROM MOST REMOTE POINT OF DRAINAGE AREA TO POINT OF
DISCHARGE @ A-2 = 65 FEET
AVERAGE SLOPE - .049
FROM OVERLAND FLOW CHART (APPENDIX X-C) T1 - 6 MlN.
"C" FACTOR OF DRAINAGE AREA A-2 0.90
DISTANCE = 35'
SLOPE = .02
10 MlN. (COUNTY DRAINAGE MANUAL)
FROM CHART T~ 1.5 USE 1 MIN.
Tc = 5 + 6 + 1 = 12 MIN.
STORM INTENSITY FACTOR I FROM INTENSITY DURATION CHART APPENDIX XI-A
Q50
Ql 00
- RUNOFF IN CFS FOR 50 YR. STORM FROM RATIONAL FORMULA Q - CI'A - RUNOFF IN CFS FOR 100 YR. STORM FROM RATIONAL FORMULA Q CIA
SHEET 3
APPENDIX I
CHARTS E GRAPHS
SHEET 4
SHEET 5
.. c 0
c. m u
P
c
" c
4
e L
U c 0
c. 0 tu
c
I - FA c
nc N m - n A n d ln
6-Hour Precipitation (inches) g
0uIoY)oIn 0 om? 0 In
..
0
..
w3 * w 4.
6-Hour Precipitation (inches) 5
olnoyou! ... . 9 8, &o ..
0
!
.
SAN DlEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
DES GN MANUAL
URBAN AREAS OVERLAND TIME
OF FLOW CURVES
APPROVED /F*kL4L f /? (*'e'
IV44 2
. .. -
1.5' 4 2 a, n: .Gin
2% .
Deplh RESIDENTIAL STREET
ONE SIDE ONLY
!
EXAMPLE:
Given: a = IO s = 2.5 */. Chart giver1 Deplh = 0.4, Velocity = 4.4 tpr.
SAN DlEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
APPROVE0 fid DATE ~-!&& I APPENDIX X-0
GUTTER AND ROADWAY
DISCHARGE-VELOCITY CHART
DESIGN MANUAL
IV-A- I3
TABLE 2
RUNOFF COEFFICIENTS (RATIONAL METHOD)
DEVELOPED AREAS (URBAN)
Land Use
Residential:
Single Family
Hulti-Units
Mobile homes
Rural (lots greater than 1/2 acre)
Comnercial(2) 80% Impervious
Industrial(2) 90% Impervious
NOTES :
- A
.40
a45
.45
.30
-70
.80
"2- Coefficient C
Soi I F~up (1)
- B C -
.45 .so
.50 .60
.50 .55
.75 . .80
.85 @
- 0
.55
. 70
.65
* 45
.85
.95
(l)s0il Group m&s are available at the 'dffices.'of the Department of Public Works.
(*)Where actual conditions deviate significantly from the tabulated impervious-
by multiplying 80% or 90% by the ratio of actual imperviousness to the
ness values of 80% or 90%. the values given for coefficient C. may be revised
be less than 0.50. For example: Consider comrcial property on 0 soil.-group.
tabulated imperviousness. However, In no case shall the final coefficient
Actual imperviousness - 50%
Tabulated imperviousness - 80% -
Revised C - 0 x 0.85 = 0.53 80
IV-A-9
APPENDIX IX-B Rev. 5/01
Group B
Soils having moderate infiltration rates when thoroughly wetted, consisting chiefly of mod-
drained soils with moderately fine to mod- erately deep to deep, moderately well to well
moderate rate of water transmission. erately coarse texturqs. These soils have a
Group C
Soils having slow infiltration rates when thoroughly wetted, consisting chiefly of (1) soils with a layer that impedes the downward movement of water, of (2) soils with moderately fine to fine texture and a
slow rate of water transmission. slow infiltration rate. These soils have a
Group D
Soils having very slow infiltration rates when thoroughly wetted, consisting ~iefly of (1) clay soils with a high swelling potential;
' (2) soils with a high permanent water table;
(3) soils with clay pan or clay layer at
nearly impervious materials. These soils have
or near the surface; and (4) shallow soils over
a very slow rate of water transmission.
Soil group and soil cover maps have been prepared by the Soil Con-
servation Service, and include most oi: the County. The maps are
available at the offices of the Department of Sanitation and flood
Control.
I
The Department of Sanitation and Flood Control has developed a computer
prop- for calculating CN numbers after soils groups and covers have
been tabulated for given basin and sub-basins. Tabulation is usually -
accomplished by using a one-half or one inch square grid and listing _' .
. the group and cover at each intersection.
The hydrologic condition of soil cover must be determined for each
basin or sub-basin. Photos and slides showing typical hydrologic
conditions of soil cover for many areas of San Diego County can be
examined at the office of the Department of Sanitation and Flood
Control 4 I-A-4 REV. 11/75
- I..
.
d
I
XI-A-7
.. 1
-i 1 1
APPENDIX II
HYDROLOGY PLANS