HomeMy WebLinkAboutCT 00-02; CALAVERA HILLS PHASE II; PRELIMINARY HYDROLOGY STUDY; 2000-01-21I
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PRELIMINARY
Em)ROLOGY STUDY
FOR
CALAVERA HILLS PHASE H
Prepared By .
O'DAY CONSULTANTS
5900 Pasteur Court, Suite 100
Carlsbad, Califoniia 92008
(760) 931-7700
January 21,2000
^orge OT)^ ^ /RCE 32014 ' CteorgeOT)X ^ / RCE32014 ' PreparedBy:
Registration Expires 12/31?00 Checked By . GO
CONSULTA/^NTS
Civil Engineering * Surveying
October 4,2001
J.N. 981020-1
Mr. Frank Jimeno
CityofCarlsbad
1635 Faraday Avenue
Carlsbad, CA 92008
Re: Calavera Hills II C.T. 00-02, Master Tentative Map Hydrology Study
Dear Frank:
The revisions to the Master Tentative Map have resulted in the developable pad areas to
be smaller than originally submitted.
The peak runoff quantities have not increased and the drainage basins have not changed.
Therefore the original preliminary Hydrology Study as submitted should be adequate for
the Tentative Map Analysis.
Very truly yours,
O'DAY CONSULTANTS, INC.
George O'Day
Project Manager
GO:pm
W:\MSOFFICE\WINWORD\981020Uimenoltr.doc
O'Day Consultants Inc.
5900 Pasteur Ct. Suite 100
Carlsbad, Califomia 92008-7317
Tel: 760 931 7700 Fax: 760 931 8680
E-mail: oday@odayconsultants.oom
Website: www.odayconsultants.oom
This preliminary drainage report has been prepared for the intial review of the tentative
maps by the City of Carlsbad.
The following references were used
• Hydrology Manual County of San Dieeo.
Dated January 1985
• Citv of Carlsbad standards for design &
r.on.struction of public works improvements
Tn the Citv of Carlsbad, dated April 20, 1993
HYDROLOGY CALCULATIONS
The hydrological analysis utilized to calculate the storm runoff for the 100 year
storm event was the Rational Method (Q = C * I * A).
Q = Runoflf (cfs),
C = Runoflf coefficient,
IA = Rainfall intensity (inches/hour)
A = Area (acres)
Tc = Time of Concentration (Initial, overland, street gutter or pipe).
Determination of Runoff Coefficient
The runoflf coefficient (C) is based on the soil group of the drainage basin.
RunofF coefficients are also dependent on the proposed land use of each basin.
Coeflficients for this project were based from the County of San Diego Hydrology
Manual.
Determination of Intensity
Rainfall intensity (I) is a fiinction of the six-hour precipitation measure and the time
of concentration for the drainage basin, as defined by the County of San Diego
Hydrology Manual
Determination of Areas
The area (A) of each drainage basin was determined from the drainage area map.
The drainage sub-basins have been based on the ultimate anticipated land use.
Hvdrologv Calculations
A summary of hydrology calculations for the developed conditions is listed in
Exhibit.
Exhibit "A" San Diego County Soil Classification Map
Exhibit "B" San Diego Covmty Rimoff Coefficients
Exhibit "C" Thomas Brother's Map - Location of Site
Exhibit "D" 1 OO-year, 24 Hour Precipitation
Exhibit "E" 1 OO-year, 6 Hour Precipitation
Exhibit "p" Intensity - Duration Design Chart
Exhibit "G" Urban Areas Overland Time of Flow Curves
Exhibit "H" Gutter and Roadway Discharge - Velocity Chart
Exhibit Nomograph for Time of Concentration for Natural Watershed
Exhibit "J" 400-Scale City of Carlsbad Topographic Map with Project Plotted
Exhibit "K" 100-Scale Composite ofthe Tentative Maps - Villages U, W, X, Y, K, L-2, and R
Exhibit "L" 40-Scale Composite of the Tentative Maps - Villages H
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TABLE 2
RUNOFF COEFFICIENTS (RATIONAL METHOD)
DEVELOPED AREAS (URBAN)
Land Use
Residential:
Single Family
Hulti-Units
Hob i I e hotnes
Rural (lots greater than l/Z acre)
Convnerci al (2)
80% Impervious
Industrial (2)
90% Impervious
Coefficient, C
Soi1 Group (1)
A B C 0
.40 .45 .50 .55
M .50 .60 .70
M .50 .55 .65
.30 .35 .40 .45
.70 .75 .80 .85
.80 .85 .90 .95
NOTES:
^'^Soil Group maps are available at the offices of the Department of Public Works.
(^)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.giroup.
Actual imperviousness = 50%
Tabulated imperviousness = 80%
Revised C » 50 x 0.85 =» 0.53
80
IV-A-9
APPENDIX IX-B
Rev. S/81
COUriTY OF SAN DIEGO
DEPARTMENT OF SANITATION 6
FLOOD COHTROL 100-YEAR 6-150U1 PfJECIPITATIOiJ
^20-/ ISOPLUVIALS
PnECIPiTATIOn IN
OF lOO-YEAR 6-HOUR
fEnins Cr AH i;:cii
33'
45'
Prepn
U.S. DEPARTMEN
SPECIAL STUDIES ORAN Ctl, OFFICC OF II
30' _
118'
d by
OF COMMERCE
NATIONAL OCEANIC AND AT^JoSI'IIEKIC ADMINISTRATION
IJROLOGV, NATIONAL WEATIIER SERVICE
I
RRVI Sfill 1/85 APPF.NniX XT-E
COUNTY OF SAN DIEGO
DEPARTMENT OF SANITATION 6-
FLOOD CONTROL
45'
33"
30'
15'
45'
Ht<p
U.S. DEPARTMLN
NATIONAL OCEANIC AND AT:.
SPECIAL STODIES BKANCII. OFI ICE OF II
30'
lur
100-YEAn 24-1101R PRECiPITATION
•20-^ ISOPLUVIALS OF 100 -YEAR 24-liOUn
PRECIPITATIOH IN |EMTIIS OF AN INCII
30' 117° 'l'l' in' |r,i llf,"
APPliNinX XI-ll
INTENSITY'-DURATION DESIGN CHART
cn
•a -» ro n
rf
su
o
l/l
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 Manual).
2) Adjust 6 hr. precipitation (if necessary) so
that it is within the range of 45% to 65% of
the 24 hr. precipitation. (Not applicable
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) Selected Frequency yr.
1) Pg " ^i^in.. P24- X =
2) Adjusted *Pg» 3
3) t^-
4) I -
94
min. 5^
in/hr.
*Not Applicable to Deser
X
Minutes Revised 1/85 APPENDIX XI-A
£xo/i7p/a -
S/o/os ' /.O '/<,
SAN DIEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
APPROVED
DESIGN MANUAL
/-<, 'A, /YfU-f ,1 -r.^r t- '
URBAN AREAS OVERLAND TIME
OF FLOW CURVES
DATE /'M APPENDIX X-
2%
ONt SlUC UIMI.i
III!
2 3 4 567B9I0
DISCHARGE (CFS.)
EXAMPLE-
Given: Q= 10 S= 2.5%
Chart gives: Depth = 0.4, Velocity = 4.4 f.ps.
20 30 I I
40 50
SAN DIEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
DESIGN MANUAL
APPROVED ^.V/VT^^^Ml^H^^feT
GUTTEFi AND ROADWAY
DISCHARGE-VELOCITY CHART
DATE APPENDIX X-D
£^A/MA>
^—/aaa
^ 90O
BOO
- TOO
- ^oo \
-SOO \
— 400
-300
Fee/
—soaa
— 4000
—zooo
—zooo
rc
PE-
L -Leng f/l of nva/ars/fed TT^
D//A:re/7Cs m a/e,/a//an cxJong
e/fecf/ire s/ooe /ina (See ^/^tendiX^-B) 7-
L
/Pf//es
/O —
\
• 200
S —
4-
3-
2-\
\
•/OO
\ -
• SO
•40
V-30
as—
NOTE
BFOR NATURAL WATERSHEDS]
— ZO M AOD TEN MINUTFS TO \ „ AOD TEN MINUTES TO ^
h COMPUTED TIME OF CON- !
JCENTRATION- J
— /O
4 —
-SOOO
\
• JOOO
— 240
/BO
/20
/OO
90
BO
70
\
- 2000 /aoo
/600
/aoo
/200
- /ooa
• 900
.800
• 700
• 600
-SOO
— 400
— 300
\
\
-60
- SO
— 40
— 30
-20
/a
/6
— /a
—/?
200
/O
9
— B
— 7
— 6
H
SAN DIEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
APPROVED
DESIGN MANUAL
"5, //, ./^^"i^^^t.^ -^Z&^k^
NOMOGRAPH FOR DETERMINATTON
OF TIME OF CONCENTRATION (Tc)
FOR NATURAL WATERSHEDS
DATE I APP
TV-A-10
APPENDIX X-A
Rev. 5/81