HomeMy WebLinkAboutHDP 89-52; Draper Residence; Hillside Development Permit (HDP) (2)does Lff Mes/? BLVD.
$TE. too, M£3A,
Off, 9^0^/
coufrry OF SAN OIEGO
DEPARTMENT OF SANITATION £•
FLOOD CONTROL 100-YEAR Z-mm PRECIPITATlOii
^20^ ISOPLUVIALS OF lOO-YEAR 6-HOUR
PnEClFiTATlOJl UJ jErSTHS D? At] lUCSJ
33*
U.S. DEPARTMEN
(PECIAt. STUDIES BRANCH. OFFICE OF II
30' .
> I
d by
r OF COMMERCE
NATIO.VAL OCEANIC AND AT>|oSP|IEKIC ADMINISTRATION
DROLOCY. NATIONAL WEATIIER SERVICE
116*
COUNTY OF SAN DIEGO
DEPARTMENT OF SANITATION t
FLOOD CONTROL
33-
100-YEAR 24-1101 R PRECIPITATION
^20^lSOPLUVIALS OF 100 -YEAR 24-HOUR
.1 .
5 r '•'ll
PnECiPITATlOIl IM EMTHS OF AN ItlCIl
•i^.rv
tPECIAL
f
U.S. DEPARTMEN
MATIOKAL OCEANIC ANO AT STtToilS BKANCII. OFFICE OP l.joROLOCT. WATIONAU WEATIIER SERVJCC
nr."
INTENSITY-DU/^ATION DESIGN CHART
15 20
Minutes
Directions for Application:
1) From precipitation naps determine 6 hr. and
24 hr. amounts for the selected frequency.
These maps are printed In the County Hydrology
Manual (10, 50 and 100 yr. maps included in the
Design and Procedure Hanual).
2) Adjust 6 hr. precipitation (if necessary) so
that it is within the range of 45% to 65« of
the 24 hr. precipitation. (Hot r.pplicable
to Desert)
3) Plot 6 hr. precipitation on the right side
of the chart.
4) Drav/ 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) Selected Frequency /^O yr.
1) Pe " ^'75 In., Pg^- 4-5 . *Pg « ALJ*
2) Adjusted *Pg« _
3) t^ » IO min.
4) I - ^.63 in/hr.
24
In.
•Not Applicable to Desert Region
APPENDIX XI
IV-A-14
Revised 1/85
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H
SAN DIEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
nc e> I H A Ml I A I
NOMOGRAPH FOR DETERMINATTON
OF TIME OF CONCE.NTRATION (Tc)
FOR NATURAL WATERSHEDS
'''' St*-*"*!
TABLE 2 \
RUNOFF COEFFICIENTS (RATIONAL METHOD)
DEVELOPED AREAS (URBAN)
Coefficient. C
Soil Grotq> (1)
Land Use
90% Impervious
V
A B C D
Residential:
Single Family .40 M .50
Multi-Units M .50 .60 .70
Mobile homes M .50 .55 .65
Rural (lots greater than 1/2 acre) .30 .35 .40 .45
Commerci al(2) .70 .75 .80 .85
80% Impervious »
Industrial(2) .80 .85 .90 .95
NOTES:
^'^Soil Group maps are available at 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%
Tabulated imperviousness - 80%
Revised C - 12 x 0.85 - 0.53
80
IV-A-9
APPENDIX IX-B Rev. 5/81
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