HomeMy WebLinkAboutCT 00-00; Carlsbad Oaks North Business Park; Carlsbad Oaks North Business Park; 1997-07-03PRELIMINARY
DRAINAGE STUDY
FOR
CARLSBAD OAKS NORTH BUSINESS PARK
JULY 3,1997
J.N. 96-1005
Prepared by O'Day Consultants, Inc.
7220 Avenida Encinas, Suite 204
Carlsbad, CA 92009
(760) 931-7700
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San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software, (c) 1993 Version 3.2
Rational method hydrology program based on
San Diego County Flood Control Division 1985 hydrology manual
Rational Hydrology Study Date: 06/18/97
CARLSBAD OAKS NORTH BUSINESS PARK
PRELIMINARY DRAINAGE STUDY
EXISTING CONDITION FOR DRAINAGE AREA 1
FILE: F:\ACCTS\961005\TMEXA1
********* Hydrology Study Control Information **********
O'Day Consultants, San Deigo, California - S/N 10125
Rational hydrology study storm event year is 100.0
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inches) = 4.900
Adjusted 6 hour precipitation (inches) = 2.800
P6/P24 = 57.1%
San Diego hydrology manual 'C' values used
Runoff coefficients by rational method
Process from Point/Station 10.000 to Point/Station 11.000
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[RURAL (greater than 1/2 acre) area type ]
Time of concentration computed by the
natural watersheds nomograph (App X-A)
TC = [11.9*length(Mi)A3)/(elevation change)]A.385 *60(min/hr) + 10 min.
Initial subarea flow distance = 3200.00(Ft.)
Highest elevation = 450.00(Ft.)
Lowest elevation = 220.00(Ft.)
Elevation difference = 230.00(Ft.)
TC=[(11.9*0.6061*3)/(230.00)]*.385= 10.76 + 10 min. = 20.76 min.
Rainfall intensity (I) = 2.945 for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.355
Subarea runoff = 89.293(CFS)
Total initial stream area = 85.400(Ac.)
Process from Point/Station 11.000 to Point/Station 11.000
**** SUBAREA FLOW ADDITION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[RURAL (greater than 1/2 acre) area type ]
Time of concentration = 20.76 min.
Rainfall intensity = 2.945(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area, Rational method,Q=KCIA, C = 0.355
Subarea runoff = 67.336(CFS) for 64.400(Ac.)
Total runoff = 156.629(CFS) Total area = 149.80(Ac.)
End of computations, total study area = 149.80 (Ac.)
San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software, (c) 1993 Version 3.2
Rational method hydrology program based on
San Diego County Flood Control Division 1985 hydrology manual
Rational Hydrology Study Date: 06/13/97
CARLSBAD OAKS NORTH BUSINESS PARK
PRELIMINARY DRAINAGE REPORT
EXISTING CONDITION FOR DRAINAGE AREA 2
FILE: F:\ACCTS\961005\TMEXA2
********* Hydrology Study Control Information **********
O'Day Consultants, San Deigo, California - S/N 10125
Rational hydrology study storm event year is 100.0
Map data precipitation entered:
6 hour, precipitation (inches) = 2.800
24 hour precipitation(inches) = 4.900
Adjusted 6 hour precipitation (inches) = 2.800
P6/P24 = 57.1%
San Diego hydrology manual 'C' values used
Runoff coefficients by rational method
Process from Point/Station 20.000 to Point/Station 21.000
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[RURAL (greater than 1/2 acre) area type ]
Time of concentration computed by the
natural watersheds nomograph (App X-A)
TC = [11.9*length(Mi)^3)/(elevation change)]A.385 *60(min/hr) + 10 rain.
Initial subarea flow distance = 1900.00(Ft.)
Highest elevation = 450.00 (Ft.)
Lowest elevation = 270.00(Ft.)
Elevation difference = 180.00(Ft.)
TC= [ (11.9*0.3598^3)/(180.00) ] A.385 = 6.48 + 10 min. = 16.48 min.
Rainfall intensity (I) = 3.419 for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.355
Subarea runoff = 98.307(CFS)
Total initial stream area = 81.000(Ac.)
End of computations, total study area = 81.00 (Ac.)
San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software, (c) 1993 Version 3.2
Rational method hydrology program based on
San Diego County Flood Control Division 1985 hydrology manual
Rational Hydrology Study Date: 06/13/97
CARLSBAD OAKS NORTH BUSINESS PARK
PRELIMINARY DRAINAGE STUDY
EXISTING CONDITION FOR DRAINAGE AREA 3
FILE: F:\ACCTS\961005\TMEXA3
********* Hydrology Study Control Information **********
— — — — —. _ — — — — — — _ — — — — — — _ — _ ____« _ _ __. — __________• — — » «• _ _ _. _. — — — ________»_______«
O'Day Consultants, San Deigo, California - S/N 10125
Rational hydrology study storm event year is 100.0
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inches) = 4.900
Adjusted 6 hour precipitation (inches) = 2.800
P6/P24 = 57.1%
San Diego hydrology manual 'C' values used
Runoff coefficients by rational method
Process from Point/Station 30.000 to Point/Station 31.000
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[RURAL (greater than 1/2 acre) area type ]
Time of concentration computed by the
natural watersheds nomograph (App X-A)
TC = [11.9*length(Mi)A3)/(elevation change)]A.385 *60(min/hr) + 10 rain.
Initial subarea flow distance = 1000.00(Ft.)
Highest elevation = 360.00(Ft.)
Lowest elevation = 220.00(Ft.)
Elevation difference = 140.00(Ft.)
TC= [ (11.9*0.1894^3)/(140.00)]^.385 = 3.40 + 10 min. = 13.40 min.
Rainfall intensity (I) = 3.906 for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.355
Subarea runoff = 38.829(CFS)
Total initial stream area = 28.000(Ac.)
End of computations, total study area = 28.00 (Ac.)
San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software, (c) 1993 Version 3.2
Rational method hydrology program based on
San Diego County Flood Control Division 1985 hydrology manual
Rational Hydrology Study Date: 07/02/97
CARLSBAD OAKS NORTH BUSINESS PARK
PRELIMINARY DRAINAGE STUDY
FUTURE CONDITION FOR DRAINAGE AREA 1
FILE: F:\ACCTS\961005\TMFUT1— — — — — — _ ______ ______ _ _ _______ _ __________________ — — — — _____________„ _.
********* Hydrology Study Control Information **********
O'Day Consultants, San Deigo, California - S/N 10125
Rational hydrology study storm event year is 100.0
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inches) = 4.900
Adjusted 6 hour precipitation (inches) = 2.800
P6/P24 = 57.1%
San Diego hydrology manual 'C' values used
Runoff coefficients by rational method
Process from Point/Station 10.000 to Point/Station 11.000
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[INDUSTRIAL area type ]
Initial subarea flow distance = 1100.00(Ft.)
Highest elevation = 516.00(Ft.)
Lowest elevation = 500.00(Ft.)
Elevation difference = 16.00(Ft.)
Time of concentration calculated by the urban
areas overland flow method (App X-C) = 12.91 min.
TC = [1.8*(l.l-C)*distanceA.5)/(% slopeA(l/3)]
TC = [1.8* (1.1-0.8550)* (1100.00^.5)/( 1.45A(l/3)]= 12.91
Rainfall intensity (I) = 4.001 for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.855
Subarea runoff = 31.475(CFS)
Total initial stream area = 9.200(Ac.)
Process from Point/Station 11.000 to Point/Station 12.000
**** piPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation =472.00(Ft.)
Downstream point/station elevation = 464.00(Ft.)
Pipe length = 970.00(Ft.) Manning's N = 0.013
Process from Point/Station 13.000 to Point/Station 14.000
**** PIPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation =295.00(Ft.)
Downstream point/station elevation = 234.00(Ft.)
Pipe length = 900.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 367.831(CFS)
Nearest computed pipe diameter = 48.00(In.)
Calculated individual pipe flow = 367.83KCFS)
Normal flow depth in pipe = 38.63(In.)
Flow top width inside pipe = 38.06(In.)
Critical depth could not be calculated.
Pipe flow velocity = 33.92(Ft/s)
Travel time through pipe = 0.44 min.
Time of concentration (TC) = 16.18 min.
Process from Point/Station 13.000 to Point/Station 14.000
**** SUBAREA FLOW ADDITION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[INDUSTRIAL area type ]
Time of concentration = 16.18 min.
Rainfall intensity = 3.459(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area, Rational method,Q=KCIA, C = 0.855
Subarea runoff = 37.859(CFS) for 12.800(Ac.)
Total runoff = 405.690(CFS) Total area = 131.60(Ac.)
End of computations, total study area = 131.60 (Ac.)
No. of pipes = 1 Required pipe flow = 31.475(CFS)
Nearest computed pipe diameter = 30.00(In.)
Calculated individual pipe flow = 31.475(CFS)
Normal flow depth in pipe = 21.14(In.)
Flow top width inside pipe = 27.37(In.)
Critical Depth = 22.95(In.)
Pipe flow velocity = 8.51(Ft/s)
Travel time through pipe = 1.90 min.
Time of concentration (TC) = 14.81 min.
Process from Point/Station
**** SUBAREA FLOW ADDITION ****
11.000 to Point/Station 12.000
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[INDUSTRIAL area type
Time of•concentration = 14.81 min.
Rainfall intensity = 3.662(In/Hr]
Runoff coefficient used for sub-area,
Subarea runoff = 165.327(CFS) for
Total runoff = 196.802(CFS) Total
for a 100.0 year storm
Rational method,Q=KCIA, C = 0.855
52.800(Ac.)
area = 62.00(Ac.)
Process from Point/Station 12.000 to Point/Station 13.000
**** PIPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation = 464.00(Ft.)
Downstream point/station elevation = 295.00(Ft.)
Pipe length = 1820.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 196.802(CFS)
Nearest computed pipe diameter = 36.00(In.)
Calculated individual pipe flow = 196.802(CFS)
Normal flow depth in pipe = 28.55(In.)
Flow top width inside pipe = 29.17(In.)
Critical depth could not be calculated.
Pipe flow velocity = 32.76(Ft/s)
Travel time through pipe = 0.93 min.
Time of concentration (TC) = 15.73 min.
Process from Point/Station
**** SUBAREA FLOW ADDITION ****
12.000 to Point/Station 13 .000
Decimal fraction soil group A.= 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[INDUSTRIAL area type ]
Time of concentration = 15.73 min.
Rainfall intensity = 3.522(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area, Rational method,Q=KCIA, C = 0.855
Subarea runoff = 171.029(CFS) for 56.800(Ac.)
Total runoff = 367.83KCFS) Total area = 118.80 (Ac.)
San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software, (c) 1993 Version 3.2
Rational method hydrology program based on
San Diego County Flood Control Division 1985 hydrology manual
Rational Hydrology Study Date: 07/02/97
CARLSBAD OAKS NORTH BUSINESS PARK
PRELIMINARY DRAINAGE STUDY
FUTURE CONDITION FOR DRAINAGE AREA 2
FILE: F:\ACCTS\961005\TMFUT2
********* Hydrology Study Control Information **********
O'Day Consultants, San Deigo, California - S/N 10125
Rational hydrology study storm event year is 100.0
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inches) = 4.900
Adjusted 6 hour precipitation (inches) = 2.800
P6/P24 = 57.1%
San Diego hydrology manual 'C' values used
Runoff coefficients by rational method
Process from Point/Station 20.000 to Point/Station 21.000
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[INDUSTRIAL area type ]
Initial subarea flow distance = 700.00(Ft.)
Highest elevation = 480.00(Ft.)
Lowest elevation = 470.00(Ft.)
Elevation difference = 10.00(Ft.)
Time of concentration calculated by the urban
areas overland flow method (App X-C) = 10.36 min.
TC = [1.8*(1.1-C)*distanceA.5)/(% slopeA(l/3)]
TC = [1.8*(1.1-0.8550)*(700.00^.5)/( 1.43^(1/3)]= 10.36
Rainfall intensity (I) = 4.611 for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.855
Subarea runoff = 31.542(CFS)
Total initial stream area = 8.000(Ac.)
Process from Point/Station 21.000 to Point/Station 22.000
**** piPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation =464.00(Ft.)
Downstream point/station elevation = 341.00(Ft.)
Pipe length = 1700.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 31.542(CFS)
Nearest computed pipe diameter = 21.00(In.)
Calculated individual pipe flow = 31.542(CFS)
Normal flow depth in pipe = 13.45(In.)
Flow top width inside pipe = 20.15(In.)
Critical depth could not be calculated.
Pipe flow velocity = 19.40(Ft/s)
Travel time through pipe = 1.46 min.
Time of concentration (TC) = 11.82 min.
Process from Point/Station
**** SUBAREA FLOW ADDITION ****
21.000 to Point/Station 22.000
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[INDUSTRIAL area type ]
Time of concentration = 11.82 min.
Rainfall intensity = 4.235(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area, Rational method,Q=KCIA, C = 0.855
Subarea runoff = 169.470(CFS) for 46.800(Ac.)
Total runoff = 201.012(CFS) Total area = 54.80(Ac.)
Process from Point/Station 22.000 to Point/Station 23.000
**** PIPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation = 341.00(Ft.)
Downstream point/station elevation = 310.00(Ft.)
Pipe length = 400.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 201.012(CFS)
Nearest computed pipe diameter = 39.00(In.)
Calculated individual pipe flow = 201.012(CFS)
Normal flow depth in pipe = 28.27(In.)
Flow top width inside pipe = 34.84(In.)
Critical depth could not be calculated.
Pipe flow velocity = 31.24(Ft/s)
Travel time through pipe = 0.21 min.
Time of concentration (TC) = 12.03 min.
m.
m
Process from Point/Station
**** SUBAREA FLOW ADDITION ****
22.000 to Point/Station 23 .000
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[INDUSTRIAL area type ]
Time of concentration = 12.03 min.
Rainfall intensity = 4.187(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area, Rational method,Q=KCIA, C = 0.855
Subarea runoff = 47.251(CFS) for 13.200(Ac.)
Total runoff = 248.263(CFS) Total area = 68.00(Ac.)
End of computations, total study area = 68.00 (Ac.)
<M
San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software, (c) 1993 Version 3.2
Rational method hydrology program based on
San Diego County Flood Control Division 1985 hydrology manual
Rational Hydrology Study Date: 06/13/97
— — — — — — — — — — — — — — — — — — — — -- — _ — — — — — ___ — -- — — — — — — — — — — — — — — — — — — — — ____..________,_.
CARLSBAD OAKS NORTH BUSINESS PARK
PRELIMINARY DRAINAGE STUDY
FUTURE CONDITION FOR DRAINAGE AREA 3
FILE: F:\ACCTS\961005\TMFUT3
********* Hydrology Study Control Information **********
— — — — — — — — — — — — ———— — — — — — — — — — — — — — — — — — «_______«___„,____ . — — — ^ _ _ _ _ . v _ _ — _ _ . _ — _ _ _ _ .
O'Day Consultants, San Deigo, California - S/N 10125
Rational hydrology study storm event year is 100.0
Map data precipitation entered:
6 hour, precipitation (inches) = 2.800
24 hour precipitation (inches) = 4.900
Adjusted 6 hour precipitation (inches) = 2.800
P6/P24 = 57.1%
San Diego hydrology manual 'C' values used
Runoff coefficients by rational method
Process from Point/Station 30.000 to Point/Station 31.000
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[INDUSTRIAL area type ]
Time of concentration computed by the
natural watersheds nomograph (App X-A)
TC = [11.9*length(Mi)A3)/(elevation change)]A.385 *60(min/hr) + 10 min.
Initial subarea flow distance = 500.00 (Ft.)
Highest elevation = 390.00(Ft.)
Lowest elevation = 268.00 (Ft.)
Elevation difference = 122.00(Ft.)
TC= [ (11.9*0.0947^3)/(122.00)]A.385 = 1.61 + 10 min. = 11.61 min.
Rainfall intensity (I) = 4.285 for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.855
Subarea runoff = 16.486(CFS)
Total initial stream area = 4.500(Ac.)
Process from Point/Station 31.000 to Point/Station 32.000
**** pipEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation =268.00(Ft.)
Downstream point/station elevation = 250.00(Ft.)
Pipe length = 850.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 16.486(CFS)
Nearest computed pipe diameter = 21.00(In.)
Calculated individual pipe flow = 16.486(CFS)
Normal flow depth in pipe = 13.13(In.)
Flow top width inside pipe = 20.33(In.)
Critical Depth = 17.93(In.)
Pipe flow velocity = 10.42(Ft/s)
Travel time through pipe = 1.36 min.
Time of concentration (TC) = 12.97 min.
Process from Point/Station 32.000 to Point/Station 32.000
**** SUBAREA FLOW ADDITION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.900
Decimal fraction soil group C = 0.100
Decimal fraction soil group D = 0.000
[INDUSTRIAL area type ]
Time of.concentration = 12.97 min.
Rainfall intensity = 3.989(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area, Rational method,Q=KCIA, C = 0.855
Subarea runoff = 93.799(CFS) for 27.500(Ac.)
Total runoff = 110.285(CFS) Total area = 32.00(Ac.)
Process from Point/Station 32.000 to Point/Station 33.000
**** piPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation =250.00(Ft.)
Downstream point/station elevation = 238.00(Ft.)
Pipe length = 350.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 110.285(CFS)
Nearest computed pipe diameter = 36.00(In.)
Calculated individual pipe flow = 110.285(CFS)
Normal flow depth in pipe = 26.53(In.)
Flow top width inside pipe = 31.70(In.)
Critical depth could not be calculated.
Pipe flow velocity = 19.75(Ft/s)
Travel time through pipe = 0.30 min.
Time of concentration (TC) = 13.26 min.
End of computations, total study area = 32.00 (Ac.)
m
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4.1d UseofQavg
An average flow Qavg, rather than peak flow, is used to find the required surface
area of sediment basins and traps. The rational formula is still applied, except
that an average precipitation intensity instead of the peak intensity is used:
Qavg = C X j'av8 X A
Average precipitation intensity tavg is determined by taking the total rainfall
for a specified storm return period and duration (e.g., 10-year, 6-hr storm) and
dividing that total by the number of hours of duration:
total 6-hr rain
A 6-hr storm duration is suggested. Sediment basins designed with a 6-hr storm
strike a reasonable compromise between being somewhat undersized during
storm peaks and being somewhat oversized during the rest of the storm.
)O
-£»AOO "EiKE^O 1CUVJTY
IS OS(E>> TO D<ETE^.M»jue ^ 10 VR
OF" )-**> •
P — I o\ •~~ i • J \S)
^ ,'
OK)
A, =1.2Q
where A, is the appropriate surface area for trapping particles of a certain size
and V, is the settling velocity for that size particle.
B.I
TABLE 8.1 Surface Area Requirements of Sediment Traps and Basins
Particle size, mm
Settling velocity,
ft/sec (m/sec)
Surface area requirements,
ft2 per ft3/sec (nr per m3/sec
discharge discharge)
0.5 (coarse sand)
0.2 (medium sand)
0.1 (fine sand)
0.05 (coarse silt)
0.02 (medium silt)
0.01 (fine silt)
0.005 (clay)
0.19 (0.058)
0.067 (0.020)
0.023 (0.0070)
0.0062 (0.0019)
0.00096 (0.00029)
0.00024 (0.000073)
0.00006 (0.000018)
6.3
17.9
52.2
193.6
1,250.0
5,000.0
20,000.0
(20.7)
(58.7)
(171.0)
(635.0)
(4,101.0)
(16,404.0)
(65,617.0)
34 68 10 ' 2 34 6810
Fall velocity, frsec
10 ' 2345 10°
32'F 10'C)
4I'F (5"CI\
i 50-F MO"CA -
59'r [15
10 •
.OOCW6
10"
10 '' \o~' 10 • 10 J ^
q6
I ' t I I It) I I I I I I ll| I i ! I I ! ll| I I I I I I I I
34 63 i'o '• 2 34 6dlo' 2 34 63 |Q ' 2 34 6 U
00029
F.iH velocitv, m/sec
Fig. 8.1'J Particle settling velocity curves. (7)
OK)8,14-
1.2Q
where A, is the appropriate surface area for trapping particles of a certain size
and Vs is the settling velocity for that size particle.
E S. 12
\ F F£
TABLE 8.1 Surface Area Requirements of Sediment Traps and Basins
Surface area requirements.
Settling velocity, ft2 per ft3/sec (m2 per m3/sec
Particle size, mm ft/sec (m/sec) discharge discharge)
0.5 (coarse sand)
0.2 (medium sand)
0.1 (fine sand)
0.05 (coarse silt)
0.02 (medium silt)
0.01 (fine silt)
0.005 (clav)
0.19 (0.058) 6.3 (20.7)
0.067 (0.020) 17.9 (58.7)
0.023 (0.0070) 52.2 (171.0)
0.0062 (0.0019) 193.6 (635.0)
0.00096 (0.00029) 1,250.0 (4,101.0)
0.00024 (0.000073) 5,000.0 (16,404.0)
0.00006 (0.000018) 20,000.0 (65,617.0)
•I •> 't t Ht| ' I M I I II] I r ! I I I III I I I I I I I l| I | I I I I ll| t - I
34 68 ,0 •, 2 34 6 a,0 • 2 34 63|0J 2 34 6S,0.' 2 34 ti U1U ' 2 3
00029
Fjll velocity rn.-sec
Fig. 8.12 Particle settling velocity curves. IT)
TO
THE
Ta(3l«5-1 Standard Sieve Sizes-All Available in 3-in-
Oiameter Sieves; Most Al*> Available in 12-
and 18-in, Diameters
(U_S. Bureau of Standards and ASTM Designadotu)
A O.O~7A
Coarse ««ri
Sieve No.
(openiagrinin.}
4
'. 3*
. . 3
a
r>
. . 15 ••
1*
'• '-li
1
• '• f
i4
i
i
' Tt
i
' *
i4
es
Sieve opening!
(mm)
101.5
88.9
76.2
. 63.5
50J
44.4
38.1
3L7. •
25.4 V
r>n o ' ' .
19.1 -
15.9
12.7
1L1.
9^2
7.9C
6^5
) Flnese
Sieve No.
3t
. 4
5
' 6 .
i
' 8
10
12
14
. : 16 .
18
20
. 25
30
35
40 •'
45
50
60
70
80
100
120
140
170
200
230
270
325
. 400
nes
Steve openings
(mm)
5.66
4.75
4.00
3.36
2.33
i38
2.00
1.53
L41
L19
LOO
0.84
0.71
0.59
0.50
0.42
0.35 .
0.297
0.2500.210
0.177
0.149
0.125
0.105
0.088
0.074 O
0.062
0.053
0.044
0.037
^ 0-015
o.oOG2_
o.os 0.00^7
X=
uoC! TV
/-S A
A P PiC ! £" N-'T"
i .vJ THlT
F:^' eoeFf »c
As
C, - o,
m
.EAS//0 1
- C x l^t x A
</.OK
= 0.g>SS xGB ^
A -R.EQ' D
<
BAS),\j 3
- O.^SS xO.-^2 >r3>2 ct
A'^A'^^
< 30 "70 OK
Ml
OF THE
5.2a The Equation
The general form of the universal soil loss equation is:
A = RXKXLSXCXP
where A = soil loss, tons/Caere) (year)
R = rainfall erosion index, in 100 ft • tons/acre X in/hr
K = soil erodibility factor, tons/acre per unit of R
LS = slope length and steepness factor, dimensionless
C = vegetative cover factor, dimensionless
P = erosion control practice factor, dimensionless
TME THE
m
m
Erosion and Sediment Control Handbook
2.0 2.5 3.0 3.5
p = 2-year, 6-nr rain, in
Fig. 5.3 Distribution of storm types in the
western United States. (4) Type' II storms
occur in Arizona, Colorado, Idaho, Montana,
Nevada, New Mexico, Utah, and Wyoming
also.
75 100
D = 2-year, 6-hr rain, mm
Fig. 5.5 Relations between average annual erosion index and 2-year, 6-hr rainfall in
California. (14)
The differences in peak intensity are reflected in the coefficients of the equa-
tions for the rainfall factor. Figure 5.5 is a graphical representation of the equa-
tions. The equations, also shown on the curves for each individual storm type,
are:
R = Zip2-2 type II
R = 16.55p2'2 type I <—
R = 10.2p22 type IA
/s
A )0
op
THE"
10
O
is i FACTOR K"
OP
0
-2.0 % S ' CT
^ CExarroe 5-4)
^"'^o^
BEST ORIGINAL
THE COV&-R FACTOR T^UET L-l^TS^ "BELOW AR<E.
C - 0.01
TABLE 5.6 C Values for Soil Loss Equation*
Type of cover
None
Native vegetation (undisturbed)
Temporary seedings:
90 ""c cover, annual grasses, no mulch
Wood fiber mulch, % ton/acre (1.7 t/ha), with seedt
Excelsior mat, jutet
Straw mulcht
1.5 tons/acre (3.4 t/ha), tacked down
4 tons/acre (9.0 t/ha), tacked down
C factor
1.0
0.01
0.1
0.5
0.3
0.2
0.05
Soil loss
reduction, %
0
99
90
50
70
80
95
'Adapted from Refs. 11, 15, and 20
tFor slopes up to 2:1.
»' >l
0^.
FOT2.
TABLE 5.7 P Factors for Construction Sites (Adapted from Ref. 15)
Surface condition P value
Compacted and smooth 1.3
Trackwalked along contour* 1.2
Trackwalked up and down slopet 0.9
Punched straw 0.9
Rough, irregular cut 0.9
Loose to 12-in (30-cm) depth 0.8
•Tread marks oriented up and down slope.
tTread marks oriented parallel to contours, as in Figs. 6.9 and 6.10.
si
AC
•2-0
L. -
; <2- 2_
L-S
LS --I- O.
AC -5"O
Scope HT - 'SO t L. - SOO Q "2 '.
EN>C-nv\ - BOO ' G> '2-%
SCOPE'S =
- o, s( so. <ar?)
S0!i_
P.- GB K- O.2-4
.-- o.o\ p- o.^>
O.o\ A
O.4O x 1^-2. AC-
J>e»05»TY OP MO ib/CT
OK
Z. L.S- 3/73
A-
- 33
MO
S L.S>- /9-Co
'-A . G^ v o.*z>4- v /^G vo.o
SOU-
^5*2.0 .'. OK
,S Values* (10)
LS values
10
(3.0)
0.06
0.08
0.10
0.14
0.16
0.17
0.21.
0.26
0.31
0.37
0.43
0.50
0.61
0.81
0.96
1.29
1.51
1.86
2.51
2.98
3.23
4.00
4.81
5.64
6.48
6.82
7.32
8.44
8.98
9.78
10.55
11.30
12.02
12.1.
13.3R
20
(6.1)
0.07
0.09
0.12
0.18
0.21
0.24
0.30
0.37
0.44
0.52
0.61
0.71
0.86
1.14
1.36
1.82
2.13
2.63
3.56
4.22
4.57
5.66
6.80
7.97
9.16
9.64
10.35
11.93
12.70
13.83
14.93
15.98
17.00
l7.97f
18.89
30
(9.1)
0.07
0.10
0.14
0.20
0.25
0.29
0.37
0.45
0.54
0.64
0.75
0.86
1.05
1.40
1.67
2.23
2.61
3.23
4.36
5.17
5.60
6.93
8.33
9.76
11.22
11.80
12.68
14.61
15.55
16.94
18.28
19.58
20.82
_Jbi
23.14
for
40
(12.2)
0
0
0
0
0
0
.08
.10
.15
.22
.28
.34
0.43
0.52
0.63
0.74
0.87
1.00
1.22
1.62
1,.92
2.58
3.02
3.73
5..03
5.96
6.46
8.00
9.61
11.27
12.96
13.63
14.64
16.
17.
88
96
19.56
21.11
22.
24.m
61
04m
26.72
following slope lengths
50
(15.2)
0.08
0.11
0.16
0.23
0.30
0.38
0.48
0.58
0.70
0.83
0.97
1.12
1.36
1.81
2.15
2.88
3.37
4.16
5.62
6.67
7.23
8.95
10.75
12.60
14.48
15.24
16.37
18.87
20.08
21.87
23.60
25.27
26.88
2f.^
29.87
60
(18.3)
0.09
0.11
0.17
0.25
0.33
0.41
0.52
0.64
0.77
0.91
1.06
1.22
1.49
1.98
2.36
3.
3.
4.
6.
7.
7.
9.
11.DE
15.
16.
16
69
56
16
30
92
80
77
HI
87
69
17.93
20.67
21.
23.
25.
27.
29.
31.
32.
99
95
85
69
44
f_
72
70
(21.3)
0.09
0.12
0.18
0.26
0.35
0.45
0.56
0.69
0.83
0.98
1.15
1.32
1.61
2.14
2.54
3.41
3.99
4.93
6.65
7.89
8.55
10.59
12.72
] 14.91
17.14
18.03
19.37
22.32
23.75
25.87
27.93
29.90
31.80
l33.6f
35.34
/, ft (tn)
80
(24.4)
0.09
0.12
0.19
0.27
0.37
0.48
0.60
0.74
0.89
1.05
1.22
1.41
1.72
2.29
2.72
3.65
4.27
5.27
7.11
8.43
9.14
11.32
13.60
15.94
18.32
19.28
20.71
23.87
25.39
27.66
29.85
31.97
34.00
11.94 1
37.78
90
(27.4)
0.09
0.12
0.19
0.28
0.38
0.51
0.64
0.78
0.94
1.11
1.30
1.50
1.82
2.43
2.88
3.87
4.53
5.59
7.54
8.95
9.70
12.00
14.42
16.91
19.43
20.45
21.96
25.31
26.93
29.34
31.66
33.91
36.06
F..1I2
40.08
100
(30.5)
0.10
0.12
0.20
0.29
0.40
0.53
0.67
0.82
0.99
1.17
1.37
1.58
1.92
2.56
3.04
4.08
4.77
5.89
7.95
9.43
10.22
12.65
15.20
17.82
20.48
21.55
23.15
26.68
28.39
30.92
33.38
35.74
38.01
42.24
BEST ORIGINAL
• i ti i
150
(46)
0.10
0.14
0.23
0.32
0.47
0.66
0.82
1.01
1.21
1.44
1.68
1.93
2.35
3.13
3.72
5.00
5.84
7.21
9.74
11.55
12.52
15.50
18.62
21.83
25.09
26.40
28.35
32.68
34.77
37.87
40.88
43.78
46.55
r,i 74
200
(61)
0.11
0.14
0.25
0.35
0.53
0.76
0.95
1.17
1.40
1.66
1.94
2.23
2.72
3.62
4.30
5.77
6.75
8.33
11.25
13.34
14.46
17.89
21.50
25.21
28.97
30.48
32.74
37.74
40.15
43.73
47.20
50.55
53.76
50 74
250
(76)
0.11
0.15
0.26
0.38
0.58
0.85
i .06
1.30
1.57
1.85
2.16
2.50
3.04
4.05
4.81
6.45
7.54
9.31
12.57
14.91
16.16
20.01
24.03
28.18]
32.39
34.08
36.60
42.19
44.89
48.89
52.77
56.51
60.10
WTTTT^O
fifi 70
LS
300
(91)
0.12
0.16
0.28
0.40
0.62
0.93
1.16
1.43
1.72
2.03
2.37
2.74
3.33
4.43
5.27
7.06
8.26
10.20
13.77
16.33
17.70
21.91
26.33-^. i ">rp.sTi
35.48
37.33
40.10
46.22
49.17
53.56
57.81
61.91
values for following slope
350
(107)
0.12
0.16
0.29
0.42
0.66
1.00
1.26
1.54
1.85
2.19
2.56
2.95
3.59
4.79
5.69
7.63
8.92
11.02
14.88
17.64
19.12
23.67
28.44
33.34
38.32
40.32
43.31
49.92
53.11
57.85
62.44
66.87
65.84 71.11
69.1315. 17l
T.\ 17 70.03
400
(122)
0.13
0.16
0.30
0.43
0.70
1.07
1.34
1.65
1.98
2.35
2.74
3.16
3.84
5.12
6.08
8.16
9.54
11.78
15.91
18.86
20.44
25.30
30.40
35.65
40.97
43.10
46.30
53.37
56.78
61.85
66.75
71.48
76.02
^e^KQ
84 40
450
(137)
0.13
0.17
0.32
0.45
0.73
1.13
1.43
1.75
2.10
2.49
2.90
3.35
4.08
5.43
6.45
8.65
10.12
12.49
16.87
20.00
21.68
26.84
32.24
37.81
43.45
45.72
49.11
56.60
60.23
65.60
70.80
75.82
80.63
HO.fil
500
(152)
0.13
0.17
[033]
0.46
0.76
1.20
1.50
1.84
2.22
2.62
3.06
3.53
4.30
5.72
6.80
9.12
10.67
13.17
17.78
21.09
22.86
28.29
33.99
39.85
45.80
48.19
51.77
59.66
63.48
69.15
74.63
79.92
84.99
'89. 8v
04. 4 fi
lengths
600
(183)
0.14
0.18
[ 0.34
0.49
0.82
1.31
1.65
2.02
2.43
2.87
3.35
3.87
4.71
6.27
7.45
9.99
11.68
14.43
19.48
23.10
25.04
30.99
37.23
43.66
50.18
52.79
56.71
65.36
69.54
75.75
81.76
87.55
93.11
5|8.42l
103.48
/, ft (m)
700
(213)
0.14
0.18
0.51
0.87
1.42
1.78
2.18
2.62
3.10
3.62
4.18
5.08
6.77
8.04
10.79
12.62
15.58
21.04
24.95
27.04
33.48
40.22
47.16
54.20
57.02
61.25
70.60
75.12
81.82
88.31
94.57
100.57tJlho
111.77
800
(244)
0.14
0.19
0.54
0.92
1.51
1.90
2.33
2.80
3.32
3.87
4.47
5.43
7.24
8.60
11.54
13.49
16.66
22.49
26.67
28.91
35.79
42.99
50.41
57.94
60.96
65.48
75.47
80.30
87.46
94.41
101.09
107.51
1 10.48
9c;
(*) £\^ K\
oj
o|
1 01
oj°!
i!
2
2
2
3
4
4
5
7
9
12
14
17
23!
28ti
30|
37}
45(
53|
61!
64!
691
80S
85|
92!
ioo|
107!
12()(
1 9.1-
COUNTY OF SAN DIEGO
DEPARTMENT OF SANITATION
FLOOD CONTROL
30'
15'
33'
10-YEAR 6-
16- iSOPLUViALS OF 10-YEAR
CDo:o
PRECIPITATION IN TENTHS OF AN INCH
inCD
m 11 i * p»bf • till I •
U.S. DEPARTMET OF COMMPPHF
OUNTY OF SAN DIEGO
EFARTMENT OF .SANITATION £•
LOOD CONTROL 100-YEAR 6-HOOfl PRECIPITATION
"20.x ISOPI.UVIALS
PRECIPITATION IN
!OF 100-YEAR 6-HOUR
ENTHS 0? AN IIJCII
o
(£.o
UJ
£D
33°
t i I I I
U.S. DFPAPTMFA'!
III! II I 1 II II
NTY OF SAN
ARTMENT OF
OD CONTROL
DIEGO
SANITATION S-
30'
15
33'
100-YEAR 24-1301
20-xlSQPLUMLS 0
PRECIPITATION IN
R PRECIPITATION
f 100 -YEAR 24-HOUR
EMTHS OF AN INCH
O
t»UJ
CD
• • iii«rf . lU t| 1 I • II
r»-r»tf.-Mii« r»r» or\»/lR« 17 r>r>t?
I! 1111
TABLE 2
RUNOFF COEFFICIENTS (RATIONAL METHOD)
DEVELOPED AREAS (URBAN)
Coefficient, C
So?I Group (1)
Land Use
A J3 C D
Residential:
Single Family .40 .1*5 .50 .55
Multi-Units .45 .50 .60 .70
Mobile homes .45 .50 .55 .65
Rural (lots greater than 1/2 acre) .30 .35 .40 .45
Commercial(2) .70 .75 .80 .85
80% Impervious
Industrial (2) .80 ).85[ .90 .95
90% Impervious
NOTES :
Grou mans are available at the offices of the Department of Public Works.
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 soi I ...group.
Actual imperviousness = 50%
Tabulated imperviousness = 80%
Revised C = 12 x 0.85 = 0-.53
80
IV-A-9
APPENDIX IX-BRev. 5/81
II II I 1 11 II II II i • i • i • i • i •
"57 Ti"r pTflTrrmnrhTTT
| Equation: I
I
7in:iiirnumr:;
7.44 P£ Do
I l.l-.j ILllMI
-.645
Intensity (In./Hr.)
6 » 6 Hr. Precipitation (In.)
... D = Duration (Min.)
15 20
Minutes
30 40 5.0 1
Duration
2 . 3
Hours
4 5 6
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 th
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) 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 IOO yr.
1) P " 2.9in.. P=
2) Adjusted
3) t =C ji— "-"''"-• ii
4) I =
in.
min.
In/hr.
*Not Applicable to Desert Region
BEST ORIGINAL APPENDIX XI
IV-A-14
Revised 1/85
/itf/
— S~000
— 4000
rc
2.000
~/000
900
BOO
700
600 \
— 500
— 400
-300
- 7//7?e of
- Length of watershed
- Dfffare/jce /ft e/fvah'an a/oay
e/fecf/re s/ooe tine (Set #/>pcnd/X /•£) j-
feet //oc//-s
4
SO —
\
\
\
\
.
\ -
\-
-S0
-40
— 30
— 20
NOTE
IFOR NATURAL WATERSHED^]
n ADD TEN MINUTES TO
COMPUTED TIME OF CON-
CENTRATION- J
— JO
— 5
— /OO
~—8O
— 7O
— 30
• 4000
— 3O00 \
\
— 2000 \\
\
• /ooa
•900
• 800
• 700
— 600
— 300
2OO
/SO
•/B
• /£
9
3
7
•6
— 4-
— 3
H
SAN DIEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
DESIGN MANUAL
APPROVED ^,/y
NOMOGRAPH FOR DETERMINATION
OF TIME OF CONCENTRATION (Tc)
FOR NATURAL WATERSHEDS
DATF r^IV-A-
APPENDIX X-A10 Rev. 5/81
-t*
m
m
'M
m
m
m
RUNOFF CURVE NUMBERS FOR HYDROLOGIC SOIL-COVER COMPLEXES (CN)
TABLE I-A-1
AMC 2
la = 0.'2S
Cover
, ,, Treatment _Land Use Qf Practice3
Water Surfaces
(during floods)
Urban
Commercial -industrial
High density residential
Medium density residential
Low density residential
Barren
Fallow Straight row
Vineyards (see accompanying
disked
annual grass or
legume cover
Roads (hard surface)
(dirt)
Row crops Straight row
Contoured
Narrowleaf chaparral
Hydro log ic
Soil Groups
Hydro logic
Condition* A B C
97 98 99
89 90 91
75 82 88
73 80 86
70 78 84
78 86 91
76 85 90
land-use descript ion)
76 85 90
Poor
Fair
Good
65 78 85
50 69 79
38 61 74
74 84 90
72 82 87
Poor
Good
Poor
Good
Poor
Fair
72 81 88
67 78 85
70 79 84
65 75 82
71 82 88
55 72 81
0
99
92
90
88
87
93
92
92
89
84
80
92
89
91
89
88
86
91
86
I-A-5
II II I J5
3.0 | ! ! 1 111' .U .1-1
RUNOFF EQUATION
1100 1 I I I 1
BEST ORIGINAI
CN
toc
ro
COUNTY OF
SAN DIEGO
60 DEPARTMENT OF
SANITATION AND
55 FLOOD CONTROL
1.0 1.5 2.0
Precipitation in inches