HomeMy WebLinkAboutCT 08-01; LA COSTA VIEWS; DRAINAGE STUDY; 2009-06-04I
DRAINAGE STUDY
1 FOR
' LA COSTA VIEW HOMES
LOTS 406-407
I CT-08-01
La Costa, Carlsbad
San Diego County, California
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Owner:
I LEGACY DEVELOPMENT, LLC.
STEVE GRADY
7938 Ivanhoe Ave., Suite B
I La Jolla, CA 92037
(619) 491-9200
Engineer:
MASSON & ASSOCIATES, INC.
200 E. Washington Ave., Suite 200
Escondido, CA 92025
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I By:
Scott L. Lee RCE C70889
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Date Prepared: June 4, 2009
P.N. 00040
10
'q?'0FESS
L.
C70889
EXPJ
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PROJECT DESCRIPTION:
The proposed project is located on La Costa Avenue, Carlsbad, California. The
project consists of 8 condominium units and underground parking lot. The site is
accessible from La Costa Avenue. The entire site is approximately 0.75 Ac.
The property is currently rough graded with the majority of the site (0.46 acres)
draining toward La Costa Avenue. Approximately 0.22 acres drains north towards an
existing brow ditch which drains in the easterly direction and continues on the
neighboring property to the east. The remaining portion of the site north of the existing
brow ditch sheet flows of the property into the natural open space north of the property.
Currently there are no existing structures on the property.
METHODOLOGY:
The Rational Method as outlined in the San Diego County Hydrology Manual
dated June 2003 was used to determine the peak storm water runoff rates discharging the
site in the 100-year frequency storm event. The predominant soil group existing on the
site is soil group C. The CivilCaddlCivilDesign Engineering Software was used to
calculate the peak runoff rates. Appendix A contains reference charts and figures used
from the San Diego County Hydrology Manual.
HYDRLOGY:
In the existing condition the property is rough graded. Most of the site (basins
2.02, 2.03, total of 0.46 ac) currently drains towards the curb and gutter in La Costa
Avenue. Offsite areas (Basins 2.01 and 2.04, 0.46 ac) contribute to this runoff.
The north portion of the property (basin 1.01, 0.22 ac) drains northerly to an
existing brow ditch that drains in the easterly direction and continues on the neighboring
property. A small portion of the property (basin 1.02, 0.05 ac), located north of the
existing brow ditch, drains in the northerly direction into the natural open space.
Hydrology calculations for the existing condition are located in Appendix B. A pre-
development hydrology map is included as Exhibit 'B'.
In the post-construction condition reduced undisturbed slope area in the north part
of the site (basin 1.01, 0.16ac) will continue draining towards the existing brow ditch.
Basin 1.02 located north from the existing brow ditch will keep draining in the northerly
direction, unchanged from the pre-development condition. The rest of the on-site runoff
(Basin 2) will be collected using the storm drain inlets, storm drain system, trench drain
with filters and bio-swale and will be discharged into the existing curb and gutter in La
Costa Avenue. Hydrology calculations for the post-development condition are located in
Appendix C. A post-development hydrology map is included as Exhibit 'C'
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A summary of the pre and post construction runoff rates are included in the following
tables.
Table 3.1 Post-Construction Flows
Outfall Tributary Area
(acres) (cfs)
1.01 0.16 0.40
1.02 0.05 0.11
2.01 0.05 0.24
2.02 0.04 0.20
2.03 0.02 0.09
2.04 0.07 0.31
2.05 0.10 0.45
2.06 0.12 0.51
2.07 0.09 0.20
2.08 0.04 0.20
2.09 0.25 1.13
2.10 0.21 0.77
Table 3.2 Pie-Construction Flows
Outfall Tributary Area
(acres)
Qioo
(cfs)
1.01 0.22 0.56
1.02 0.05 0.11
2.01 0.25 1.1
2.02 0.21 0.32
2.03 0.25 0.39
2.04 0.20 1.0
I- IGOSIXIMUNP
The development of this site will create a small increase in runoff discharging the
site onto La Costa Avenue from 2.5 cfs in the pre-development condition to 3.2 cfs in the
post-development condition. There will be a small decrease in runoff discharging the site
from the brow ditch north of the development area from 0.56 cfs in the pre-development
condition to 0.40 cfs in the post-development condition. There will be no change in
runoff discharging the site north of the existing brow ditch. The small increase in runoff
to La Costa Avenue is not expected to adversely impact any existing drainage facilities
downstream of the project.
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APPENDIX A
I REFERENCE MATERIAL
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County of San Diego
Hydrology Manual
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Soil Groups
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San Diego County Hydrology Manual
Date: June 2003
Section: 3
Page: 6of26
Table .3-1
RUNOFF COEFFICIENTS FOR. URBAN. AREAS
Soil ype
A - B I C
. D.
Undisturbed Natural Terrain (Natural)
Low Density Residential (LDR)
Low Density Residential. (LDR
Low Density Residential .(LDR)
Medium Density Residential (MDR)
Medium Density Residential .1DR)
MediumDensity Residential iMDR
Medium Density Residential (MDR)
High Density Residential (HDR)
High Density Residential (HDR)
Commercial/Industrial (N. Corn)
Commercial/Industrial .(G. Corn)
Commercial/Industrial (O.P. Corn)
Commercial/Industrial (Limited I.)
Permanent Open Space 0' 0.20 0;25
Residential, 1.0:DU/A or:les's 10 0.27 032
Residential, 2;0 DU/A or 'less 20 0.34 0.38
Residential, 2.9 DU/A or less 25 0.38 0.41
Residential, 4.3 DU/A or less 30 0.41. 0.45
Residential, 7.3 DU/A or less 40 0.48 0.51
Residential, 10.9 DU/A or less 45 0.52 0.54
Residential, 14.5 DU/A or less 50 0.55 0.58
Residential, 24.0 DU/A or less 65 0.66 0.67
Residential, 43.0 DU/A or less 80 0.76 0.77
Neighborhood Commercial 80 0.76 0.77
General, Commercial 85 0.80 0.80
Office Professional/Commercial 90 . 0.83 0.84
Limited Industrial 90 0.83 0.84
General Industrial 95 0.87 . 0.87
0. 0.35.
036 0;41
0.42 0.46
045 0.49
0.48 0.52
0.54 0.57
/ 0.57 0.60,
0.60 0,63
0.69 0.71
0.78 0.79
0.78 0.79
0.81 0.82
0.84 085
0.84 0.85
0.87 0.87.
*The values associated with 0% impervious may be usedi for. direct calculation of the runoff coefficient as:,described in Section .3,.:L2' (representing the :Pe1''i0113 runoff
coefficient, Cp, for 'the.soil"type), or for areas that will.remain undisturbed in perpetuity. Justification must:be given that:the.area %vilL'rernain,: natural .forever '(eg.,.the area
is located in Cleveland National' Forest).
DU/A .dwelling units..per acre
NRCS = National Resources Conservation Service
3-6
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30,
1ooL15
ui
1100,
LU U-1
00
N"Nl '
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:-_ . . J
.0
EXAMPLE:
Given: Watercourse Distance (D) = 70 Feet
.Sib
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pe (a)
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Runnft Coe1lir.int (C) = 0.41
- Overland Flow Time = 9.5 Minutes
SOURCE: All port Drainage, Federal AviationAdrniristration, 1965
FIGURE
Rational Formula - OverlandTime of...Fiow.Nomog.aph
3.3
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EthMioN
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T - C
--
Feet
Te.
I = Watercøurse Dstarice nthes)
4060 Chàne in 01'evAbipo Z1,049: eftectwe slope line (See Fi9ure 34Weet)
3000 Tr-
H6urMinutes
200. .L: 240
120
UU\
500 0
400 \-
\% so
30G -
—50
\
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\ Miles Feet 30 \
1 -100
17 400 —20
—is
—3000 —16 03— so —14
40 —12
-. 30 \9r
. i20D
20 .UU0
-BG —6
70p
10 -500 4
r
I_-zoo
L. Tc
SOURCE: CatifQrra Division of Highways (1941) and Kirpiäh (1940)
FIGURE
Nomograph for Determination of
Time of Concentration (To) or Travel Time (Tt) for Natural Watersheds 3.4
Design
Point
Area "A"
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Area
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Watershed
Divide
Effeôtivè. Slope. Line Design Point
(Watershed Outlet)
Stream Profile
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Area "A" = Area. "B"
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I SOURCE: California Division of Highways (1941) and Kirpich (1940)
FIGURE
I Computation-of Effective Slope for Natural Watersheds 35
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I APPENDIX B
I PRE-DEVELOPMENT HYDROLOGY CALCULATIONS
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I San Diego County Rational Hydrology Program
Clvi LCADD/CIVILDESIGN Engineering Software,(c)1991-2005 Version 7.5
I Rational method hydrology program based on
San Diego County Flood Control Division 2003 Hydrology Manual
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Rational Hydrology Study Date: 06/04/09
Hydrology Study Control Information
LA COSTA I CARLSBAD, CA
HYDROLOGY ANALYSIS
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100-YEAR FREQUENCY EVENT
PRE-DEVELOPMENT CONDITION
LOTS 406-407
BASIN 1.01
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Program License Serial Number 4065
I English
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Rational hydrology study storm event year is 100.0
(in-lb) input data Units used
Map data precipitation entered:
6 hour, precipitation (inches) = 2.800 I 24 hour precipitation (inches) = 4.900
P6/P24= 57.1%
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San Diego hydrology manual 'C' values used
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Process from Point/Station 1.011 to Point/Station 1.012
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**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
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Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.ODU/AorLess I Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
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Initial subarea total flow distance = 55.000(Ft.)
Highest elevation = 141.000(Ft.)
Lowest elevation = 111 .500(Ft.)
Elevation difference = 29.500(Ft.) Slope = 53.636 %
Top of Initial Area Slope adjusted by User to 30.000 % I INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 100.00 (Ft)
for the top area slope value of 30.00 %, in a development type of
I 1.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 4.29 minutes
TC = [1 8*(1 .1 _C)*diStanCe(Ft.)t.5)/(% slope A(1/3)] I TC = [1.8*(1 .10. 3600)*( 100.000".S)/( 30.000A(1/3)]= 4.29
Calculated TC of 4.287 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
I Rainfall intensity (I) = 7.377(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.360
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Subarea runoff= 0.021(CFS)
Total initial stream area = 0.008(Ac.)
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Process from Point/Station 1.012 to Point/Station 1.013
IRREGULAR CHANNEL FLOW TRAVEL TIME
Estimated mean flow rate at midpoint of channel = 0.303(CFS)
Depth of flow = 0.200(Ft.), Average velocity = 3.140(Ft/s)
Irregular Channel Data
Information entered for subchannel number 1
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.75
2 0.22 0.22
3 0.75 0.00
4 1.28 0.22
5 1.50 0.75
Manning's 'N' friction factor = 0.016
Sub-Channel flow = 0.303(CFS)
I ' flow top width = 0.964(Ft.)
velocity= 3.140(Ft/s)
area = 0.096(Sq.Ft)
Froude number = 1.749
Upstream point elevation = 111 .500(Ft.)
Downstream point elevation = 106.000(Ft.)
Flow length = 201.000(Ft.)
Travel time = 1.07 mm.
Time of concentration = 5.35 mm.
Depth of flow = 0.200(Ft.)
Average velocity = 3.140(Ft/s)
Total irregular channel flow = 0.303(CFS)
Irregular channel normal depth above invert elev. = 0.200(Ft.)
Average velocity of channel(s) = 3.140(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DU/Aor Less
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Rainfall intensity = 7.059(In/Hr) for a 100.0 year storm
I Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.360 CA = 0.079
Subarea runoff= 0.538(CFS) for 0.212(Ac.)
Total runoff = 0.559(CFS) Total area = 0.220(Ac.)
Depth of flow = 0.249(Ft.), Average velocity = 3.781(Ft/s)
End of computations, total study area = 0.220 (Ac.)
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San Diego County Rational Hydrology Program
CIVILCADD/CIVl LDESIGN Engineering Software, (c) 1991-2005 Version 7.5
Rational method hydrology program based on
San Diego County Flood Control Division 2003 hydrology manual
Rational Hydrology Study Date: 06/04/09
LA COSTA
CARLSBAD, CA
HYDROLOGY ANALYSIS
100-YEAR FREQUENCY EVENT
PRE-DEVELOPMENT CONDITION
LOTS 406-407
BASIN 1.02
Hydrology Study Control Information
Program License Serial Number 4065
Rational hydrology study storm event year is 100.0
English (in-lb) input data Units used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inches) = 4.900
P6/P24= 57.1%
San Diego hydrology manual 'C' values used
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.021 to Point/Station 1.022
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[UNDISTURBED NATURAL TERRAIN
(Permanent Open Space
Impervious value, Ai = 0.000
Sub-Area C Value = 0.300
Initial subarea total flow distance = 12.000(Ft.)
Highest elevation = 107.000(Ft.)
Lowest elevation 100.500(Ft.)
Elevation difference = 6.500(Ft.) Slope = 54.167 %
Top of Initial Area Slope adjusted by User to 30.000 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 100.00 (Ft)
for the top area slope value of 30.00 %, in a development type of
Permanent Open Space
In Accordance With Figure 3-3
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I Initial Area Time of Concentration = 4.63 minutes
TC = [1.8*(1 .1 C)*distance(Ft.)A.5)I(% slope '(1I3)]
U TC = [1.8*(1.10.3000)*( 100.000A.5)/( 30.000A(1/3)]= 4.63
Calculated TC of 4.634 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 7.377(In/Hr) for a 100.0 year storm
I Effective runoff coefficient used for area (Q=KCIA) is C = 0.300
Subarea runoff= 0.111(CFS)
Total initial stream area = 0.050(Ac.)
End of computations, total study area = 0.050 (Ac.)
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San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2005 Version 7.5
Rational method hydrology program based on
San Diego County Flood Control Division 2003 Hydrology Manual
Rational Hydrology Study Date: 06/04/09
Hydrology Study Control Information
LA COSTA
CARLSBAD, CA
HYDROLOGY ANALYSIS
100-YEAR FREQUENCY EVENT
PRE-DEVELOPMENT CONDITION
LOTS 406-407
Basin 2
Program License Serial Number 4065
Rational hydrology study storm event year is 100.0
English (in-lb) input data Units used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation (inches) = 4.900
P6/P24= 57.1%
San Diego hydrology manual 'C' values used
Process from Point/Station 2.011 to Point/Station 2.012
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 99.000(Ft.)
Highest elevation = 140000(Ft.)
Lowest elevation = 138.500(Ft.)
Elevation difference = 1.500(Ft.) Slope = 1.515 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 75.00 (Ft)
for the top area slope value of 1.52 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.56 minutes
TC = [1 .8*(1. 1 _C)*distance(Ft.)A.5)/(% slope A(1/3)]
TC = [1.8*(1.10.6900)*( 75.000A.5)/( 1.520A(1/3)]= 5.56
The initial area total distance of 99.00 (Ft.) entered leaves a
remaining distance of 24.00 (Ft.)
Using Figure 3-4, the travel time for this distance is 0.45 minutes
for a distance of 24.00 (Ft.) and a slope of 1.52 %
with an elevation difference of 0.36(Ft.) from the end of the top area
Tt = [11. 9*length(Mi)A3)/(elevation change(Ft.))]A. 385 *60(min/hr)
= 0.452 Minutes
Tt=[(1 1.9-0.0045 A 3)/( 0.36)]A.385= 0.45
Total initial area Ti = 5.56 minutes from Figure 3-3 formula plus
0.45 minutes from the Figure 3-4 formula = 6.01 minutes
Rainfall intensity (I) = 6.551(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff= 1.130(CFS)
Total initial stream area = 0.250(Ac.)
Process from Point/Station 2.012 to Point/Station 2.023
IRREGULAR CHANNEL FLOW TRAVEL TIME
Depth of flow = 0.207(Ft.), Average velocity = 3.561(Ft/s)
Irregular Channel Data
Information entered for subchannel number 1: I Point number 'X' coordinate 'Y' coordinate
1 0.00 0.90
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2 30.00 0.14
3 31.65 0.00
4 31.75 0.50
Manning's 'N' friction factor = 0.016
I Sub-Channel flow = 1.130(CFS)
flow top width = 4.322(Ft.)
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' velocity= 3.561(Ft/s)
area = 0.317(Sq.Ft)
Froude number = 2.316
Upstream point elevation = 138.500(Ft.) I Downstream point elevation = 132.500(Ft.)
Flow length = 119.000(Ft.)
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Travel time = 0.56 mm.
Time of concentration = 6.57 mm.
Depth of flow = 0.207(Ft.)
Average velocity = 3.561 (Ft/s)
Total irregular channel flow = 1.130(CFS) I Irregular channel normal depth above invert elev. = 0.207(Ft.)
Average velocity of channel(s) = 3.561(Ft/s)
Process from Point/Station 2.012 to Point/Station 2.023
****
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number I
Stream flow area = 0.250(Ac.)
Runoff from this stream = 1.130(CFS)
Time of concentration = 6.57 mm.
Rainfall intensity = 6.187(In/Hr)
Process from Point/Station 2.021 to Point/Station 2.022
INITIAL AREA EVALUATION
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Decimal fraction soil group A = 0.000 I Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
I [LOW DENSITY RESIDENTIAL
(1.0 DU/A or Less
Impervious value, Ai = 0.100
I Sub-Area C Value = 0.360
Initial subarea total flow distance = 32.000(Ft.)
Highest elevation = 141.000(Ft.)
Lowest elevation = 140.300(Ft.)
I Elevation difference = 0.700(Ft.) Slope = 2.187 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 85.00 (Ft)
for the top area slope value of 2.19 %, in a development type of I 1.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 9.46 minutes
TC = [1.8*(1 .1 _C)*distance(Ft.)A.5)/(% slope "(1/3)] I TC = [1 .8*(1 .1 0.3600)*( 85.000A.5)/( 2.187A(1/3)]= 9.46
Rainfall intensity (I) = 4.889(In/Hr) for a 100.0 year storm
I Effective runoff coefficient used for area (Q=KClA) is C = 0.360
Subarea runoff = 0.035(CFS)
Total initial stream area = 0.020(Ac.)
I Process from Point/Station 2.022 to Point/Station 2.023
IRREGULAR CHANNEL FLOW TRAVEL TIME
Estimated mean flow rate at midpoint of channel = 0.202(CFS)
Depth of flow = 0.076(Ft.), Average velocity = 0.887(Ft/s)
Irregular Channel Data
Information entered for subchannel number 1
Point number 'X coordinate 'Y' coordinate
1 0.00 0.50
2 20.00 0.00
3 40.00 0.50
Manning's 'N' friction factor = 0.045
Sub-Channel flow = 0.202(CFS)
flow top width = 6.043(Ft.)
velocity= 0.887(Ft/s)
area = 0.228(Sq.Ft)
Froude number = 0.804
Upstream point elevation = 140.300(Ft.)
Downstream point elevation = 132.500(Ft.)
Flow length = 137.000(Ft.)
Travel time = 2.57 mm.
Time of concentration = 12.04 mm.
Depth of flow = 0.076(Ft.)
Average velocity = 0.887(Ft/s)
Total irregular channel flow = 0.202(CFS)
Irregular channel normal depth above invert elev. = 0.076(Ft.)
Average velocity of channel(s) = 0.887(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
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Decimal fraction soil group B = 0.000 I Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
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Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Rainfall intensity = 4.186(ln/Hr) for a 100.0 year storm I Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.360 CA = 0.076
Subarea runoff= 0.281(CFS) for 0.190(Ac.)
Total runoff= 0.316(CFS) Total area = 0.210(Ac.) I Depth of flow = 0.089(Ft.), Average velocity = 0.992(Ftls)
++++.++++++++++++++++++++++++++++.++..+.+++.+++++++..++.+..+++++++.+++
Process from Point/Station 2.011 to Point/Station 2.012
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.210(Ac.)
Runoff from this stream = 0.316(CFS)
Time of concentration = 12.04 mm.
Rainfall intensity = 4.186(In/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (mm) (In/Hr)
1 1.130 6.57 6.187
2 0.316 12.04 4.186
Qmax(1) =
1.000* 1.000* 1.130)-F
1.000 * 0.546 * 0.316) + = 1.303
Qmax(2) =
0.677* 1.000* 1.130)+
1.000* 1.000* 0.316)+= 1.081
Total of 2 streams to confluence:
Flow rates before confluence point:
1.130 0.316
Maximum flow rates at confluence using above data:
1.303 1.081
Area of streams before confluence:
0.250 0.210
Results of confluence:
Total flow rate = 1 .303(CFS)
Time of concentration = 6.568 mm.
Effective stream area after confluence = 0.460(Ac.)
Process from Point/Station 2.023 to Point/Station 2.033
IRREGULAR CHANNEL FLOW TRAVEL TIME
Estimated mean flow rate at midpoint of channel = 1 .775(CFS)
Depth of flow = 0.222(Ft.), Average velocity = 4.572(Ft/s)
Irregular Channel Data
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Information entered for subchannel number 1
Point number X coordinate 'Y coordinate
1 0.00 0.90
2 30.00 0.14
3 31.65 0.00
4 31.75 0.50
Manning's 'N' friction factor = 0.016
Sub-Channel flow = 1.775(CFS)
flow top width = 4.930(Ft.)
velocity= 4.572(Ft/s)
area = 0.388(Sq.Ft)
Froude number = 2.871
Upstream point elevation = 132.500(Ft.)
Downstream point elevation = 124.500(Ft.)
Flow length = 106.000(Ft.)
Travel time = 0.39 mm.
Time of concentration = 6.95 mm.
Depth of flow = 0.222(Ft.)
Average velocity = 4.572(Ft/s)
Total irregular channel flow = 1 .775(CFS)
Irregular channel normal depth above invert elev 0.222(Ft.)
Average velocity of channel(s) = 4.572(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Rainfall intensity = 5.963(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.585 CA = 0.386
Subarea runoff = 1 .000(CFS) for 0.200(Ac.)
Total runoff = 2.302(CFS) Total area = 0.660(Ac.)
Depth of flow = 0.239(Ft.), Average velocity = 4.825(Ftls)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.012 to Point/Station 2.031
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.660(Ac.)
Runoff from this stream = 2.302(CFS)
Time of concentration = 6.95 mm.
Rainfall intensity = 5.963(In/Hr)
+++++++1-+++.++.++.+.+..++++++++++.+++.+.+++++++++++++++++++++++++.++.+
Process from Point/Station 2.031 to Point/Station 2.032
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
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Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DU/Aor Less
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Initial subarea total flow distance = 32.000(Ft.)
Highest elevation = 134.100(Ft.)
Lowest elevation = 1 33.600(Ft.)
Elevation difference = 0.500(Ft.) Slope = 1.563 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 85.00 (Ft)
for the top area slope value of 1.56 %, in a development type of
1.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 10.58 minutes
TC = [1 .8*(1 .1 _C)*distance(Ft.)A.5)/(% slope "(1/3)]
TC = [1.8*(1.10.3600)*( 85.000A.5)/( 1.563A(1/3)]= 10.58
Rainfall intensity (I) = 4.549(lnlHr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.360
Subarea runoff = 0.049(CFS)
Total initial stream area = 0.030(Ac.)
++++++-I-+++++++4-+++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.032 to Point/Station 2.033
IRREGULAR CHANNEL FLOW TRAVEL TIME
Estimated mean flow rate at midpoint of channel = 0.229(CFS)
Depth of flow = 0.080(Ft.), Average velocity = 1.777(Ft/s)
Irregular Channel Data
Information entered for subchannel number 1 I Point number 'X' coordinate "I" coordinate
1 0.00 0.50
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2 10.00 0.00
3 20.00 0.50
Manning's 'N' friction factor = 0.030
Sub-Channel flow = 0.229(CFS) I flow top width = 3.212(Ft.)
velocity= 1.778(Ft/s)
area = 0.129(Sq.Ft) I I
Froudenumber= 1.563
Upstream point elevation = 133.600(Ft.)
Downstream point elevation = 124.500(Ft.) I Flow length = 97.000(Ft.)
Travel time = 0.91 mm.
Time of concentration = 11.49 mm.
I Depth of flow = 0.080(Ft.)
Average velocity = 1 .777(Ftls)
Total irregular channel flow = 0.229(CFS)
Irregular channel normal depth above invert elev. = 0.080(Ft.) I Average velocity of channel(s) = 1 .777(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
I Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
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Decimal fraction soil group D = 0.000 I [LOW DENSITY RESIDENTIAL
(1.0 DU/Aor Less
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360 I Rainfall intensity = 4.313(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.360 CA = 0.090 I Subarea runoff 0.339(CFS) for 0.220(Ac.)
Total runoff = 0.388(CFS) Total area = 0.250(Ac.)
Depth of flow = 0.098(Ft.), Average velocity = 2.028(Ft/s)
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Process from Point/Station 2.032 to Point/Station 2.033
CONFLUENCE OF MINOR STREAMS
Along Main Stream number 1 in normal stream number 2
Stream flow area = 0.250(Ac.) I Runoff from this stream = 0.388(CFS)
Time of concentration = 11.49 mm.
I Summary
Rainfall intensity = 4.313(ln/Hr)
of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (mm) (In/Hr)
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i 2.302 6.95 5.963
2 0.388 11.49 4.313
Qmax(1) =
1.000* 1.000* 2.302)+
1.000* 0.605* 0.388)+ = 2.537 I Qmax(2) =
0.723* 1.000* 2.302)+
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1.000 * 1.000 * 0.388) + = 2.053
Total of 2 streams to confluence:
Flow rates before confluence point:
2.302 0.388 I Maximum flow rates at confluence using above data:
2.537 2.053
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Area of streams before confluence:
0.660 0.250
Results of confluence:
Total flow rate = 2.537(CFS)
Time of concentration = 6.954 mm. I Effective stream area after confluence = 0.910(Ac.)
End of computations, total study area = 0.910 (Ac.)
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Li APPENDIX C
I POST-DEVELOPMENT HYDROLOGY CALCULATIONS
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I San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Soflware,(c)1991-2005 Version 7.5
I Rational method hydrology program based on
San Diego County Flood Control Division 2003 Hydrology Manual
I Rational Hydrology Study Date: 06/04/09
Hydrology Study Control Information
LA COSTA I CARLSBAD, CA
HYDROLOGY ANALYSIS
I 100-YEAR FREQUENCY EVENT
POST-DEVELOPMENT CONDITION
LOTS 406-407
Basin 1.01
I ---------------------------------------------
Program License Serial Number 4065
Rational hydrology study storm event year is 100.0
English (in-lb) input data Units used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inches) = 4.900
P6/P24= 57.1%
San Diego hydrology manual 'C' values used
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.011 to Point/Station 1.012
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DU/A or Less
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Initial subarea total flow distance = 40.000(Ft.)
Highest elevation = 136.500(Ft.)
Lowest elevation = 111.500(Ft.)
Elevation difference = 25.000(Ft.) Slope = 62.500 %
Top of Initial Area Slope adjusted by User to 30.000 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 100.00 (Ft)
for the top area slope value of 30.00 %, in a development type of
1.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 4.29 minutes
TC = [1 .8*(1. I _C)*distance(Ft.)A.5)/(% slope A(1/3)]
TC = [1.8-(1.1-0.3600)-( 100.000A.5)/( 30.000A(1/3)]= 4.29
Calculated IC of 4.287 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 7.377(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.360
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Subarea runoff= 0.016(CFS)
I Total initial stream area = 0.006(Ac.)
I +++.+++++++++++-I-++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.012 to Point/Station 1.013
IRREGULAR CHANNEL FLOW TRAVEL TIME
I Estimated mean flow rate at midpoint of channel = 0.220(CFS)
Depth of flow = 0.178(Ft.), Average velocity = 2.900(Ftis)
Irregular Channel Data
I Information entered for subchannel number 1:
Point number 'X coordinate 'Y coordinate
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i 0.00 0.75
2 0.22 0.22
3 0.75 0.00
4 1.28 0.22
5 1.50 0.75
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Sub-Channel flow = 0.220(CFS)
flow top width = 0.856(Ft.)
velocity= 2.900(Ft/s)
area = 0.076(Sq.Ft)
I ' Froude number = 1.715
Upstream point elevation = 111 .500(Ft.)
I
Downstream point elevation = 106.000(Ft.)
Flow length = 201.000(Ft.)
Travel time = 1.16 mm.
Time of concentration = 5.44 mm.
Depth of flow = 0.178(Ft.) I Average velocity = 2.900(Ftls)
Total irregular channel flow = 0.220(CFS)
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Irregular channel normal depth above invert elev. = 0.178(Ft.)
Average velocity of channel(s) = 2.900(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000 I Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
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[LOW DENSITY RESIDENTIAL
(1.0 DU/Aor Less
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Rainfall intensity = 6.985(ln/Hr) for a 100.0 year storm I Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.360 CA = 0.058
Subarea runoff = 0.386(CFS) for 0.154(Ac.)
I Total runoff= 0.402(CFS) Total area = 0.160(Ac.)
Depth of flow = 0.222(Ft.), Average velocity = 3.381(Ft/s)
End of computations, total study area = 0.160 (Ac.)
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Manning's 'N friction factor = 0.016
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PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2005 Version 7.5
Rational method hydrology program based on
San Diego County Flood Control Division 2003 Hydrology Manual
Rational Hydrology Study Date: 06/04/09
Hydrology Study Control Information
LA COSTA
CARLSBAD, CA
HYDROLOGY ANALYSIS
100-YEAR FREQUENCY EVENT
POST-DEVELOPMENT CONDITION
LOTS 406-407
BASIN 2
Program License Serial Number 4065
Rational hydrology study storm event year is 100.0
English (in-lb) input data Units used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inches) = 4.900
P6/P24= 57.1%
San Diego hydrology manual 'C' values used
Process from Point/Station 2.011 to Point/Station 2.012
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/AorLess )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 31 .000(Ft.)
Highest elevation = 137.000(Ft.)
Lowest elevation = 136.500(Ft.)
Elevation difference = 0.500(Ft.) Slope = 1.613%
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 75.00 (Ft)
for the top area slope value of 1.61 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.45 minutes
TC = [1 .8*( 1.1 _C)*distance(Ft.).5)/(% slope A(1/3)]
TC = [1.8*(1.10.6900)*( 75.000".S)/( 1.613A(1/3)]= 5.45
Rainfall intensity (I) = 6.979(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Masson and Associates, Inc. 6/4/2009
H PN 0040
LA COSTA VIEWS HOMES
I Subarea runoff= 0.241(CFS)
LOTS 406-407
Total initial stream area = 0.050(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.012 to Point/Station 2.022
PIPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation = 134.000(Ft.)
Downstream point/station elevation = 133.040(Ft.)
Pipe length = 92.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 0.241(CFS)
Nearest computed pipe diameter = 6.00(ln.)
Calculated individual pipe flow = 0.241(CFS)
Normal flow depth in pipe= 2.71(ln.)
Flow top width inside pipe= 5.97(ln.)
Critical Depth = 2.96(ln.)
Pipe flow velocity = 2.79(Ftis)
Travel time through pipe = 0.55 mm.
Time of concentration (TC) = 6.00 mm.
Process from Point/Station 2.012 to Point/Station 2.022
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number I
Stream flow area = 0.050(Ac)
Runoff from this stream = 0.241 (CFS)
Time of concentration = 6.00 mm.
Rainfall intensity = 6.559(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.021 to Point/Station 2.022
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/Aor Less
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 35000(Ft.)
Highest elevation = 137.000(Ft.)
Lowest elevation = 136.500(Ft.)
Elevation difference = 0.500(Ft.) Slope = 1.429 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 65.00 (Ft)
for the top area slope value of 1.43 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.28 minutes
TC = [1 .8*(1 .1 _C)*distance(Ft.)/.5)/(% slope A(1/3)]
TC = [1.8-(1.1-0.6900)*( 65.000A.5)/( 1 .429A(1/3)]= 5.28
Rainfall intensity (I) = 7.120(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (QKClA) is C = 0.690
Masson and Associates, Inc. 6/4/2009
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H PN 0040
LA COSTA VIEWS HOMES
I Subarea runoff= 0.197(CFS)
LOTS 406-407
Total initial stream area = 0.040(Ac.)
Process from Point/Station 2.021 to Point/Station 2.022
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: I in normal stream number 2
Stream flow area = 0.040(Ac.)
Runoff from this stream = 0.197(CFS)
Time of concentration = 5.28 mm.
Rainfall intensity = 7.120(ln/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (mm) (In/Hr)
I I 0.241 6.00 6.559
2 0.197 5.28 7.120
Qmax(1) =
1.000* 1.000* 0.241)+ I 0.921 * 1.000 * 0.197) + = 0.422
Qmax(2) =
I
1.000* 0.881* 0.241)-f
1.000 * 1.000 * 0.197) + = 0.409
Total of 2 streams to confluence:
Flow rates before confluence point: I 0.241 0.197
Maximum flow rates at confluence using above data:
I 0.422 0.409
Area of streams before confluence:
0.050 0.040
Results of confluence:
Total flow rate = 0.422(CFS) I Time of concentration = 5.999 mm.
Effective stream area after confluence = 0.090(Ac.)
Process from Point/Station 2.022 to Point/Station 2.032
PIPEFLOW TRAVEL TIME (Program estimated size)
Upstream point/station elevation = 133.040(Ft.)
Downstream point/station elevation = 132.280(Ft.)
Pipe length = 72.00(Ft.) Manning's N = 0.013
No. of pipes = I Required pipe flow = 0.422(CFS)
Nearest computed pipe diameter = 6.00(In.)
Calculated individual pipe flow = 0.422(CFS)
Normal flow depth in pipe = 3.81(ln.)
Flow top width inside pipe = 5.78(In.)
Critical Depth = 3.97(In.)
Pipe flow velocity = 3.21(Ft/s)
Travel time through pipe = 0.37 mm.
Time of concentration (TC) = 6.37 mm.
Masson and Associates, Inc. 6/4/2009
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I PN 0040
LA COSTA VIEWS HOMES
I Process from Point/Station 2.022 to Point/Station 2.032
LOTS 406-407
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.090(Ac.)
Runoff from this stream = 0.422(CFS)
Time of concentration = 6.37 mm.
Rainfall intensity = 6.308(ln/Hr)
+++++++.++++++++++++++++++++++++++++++++++++++++++++++++++++.+++++++++
Process from Point/Station 2.031 to Point/Station 2.032
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less
Impervious value, Al = 0.650
Sub-Area C Value = 0.690
Highest elevation = 137.000(Ft.) I Lowest elevation = 136.500(Ft.)
Elevation difference = 0.500(Ft.) Slope = 2.500 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 90.00 (Ft) I for the top area slope value of 2.50 %, in a development type of
24.0 DU/A or Less
I In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.16 minutes
TC = [1.8*(1 .1 C)*distance(Ft.)A.5)/(% slope A(1/3)]
TC = [1.8*(1.10.6900)*( 90.000A.5)/( 2.500A(1/3)]= 5.16
Rainfall intensity (I) = 7.230(In/Hr) for a 100.0 year storm I Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.090(CFS)
I Total initial stream area = 0.018(Ac.)
Process from Point/Station 2.031 to Point/Station 2.032
I **** CONFLUENCE OF MINOR STREAMS
Along Main Stream number: I in normal stream number 2
I Stream flow area = 0.018(Ac.)
Runoff from this stream = 0.090(CFS)
Time of concentration = 5.16 mm.
Rainfall intensity = 7.230(In/Hr)
I Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (mm) (In/Hr) I 1 0.422 6.37 6.308
2 0.090 5.16 7.230
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Masson and Associates, Inc. 6/4/2009
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Initial subarea total flow distance = 20.000(Ft.)
1.000* 1.000* 0.422)i-
0.872 * 1.000 * 0.090) + = 0.500
Qmax(2) =
1.000 * 0.809 * 0.422) +
1.000* 1.000* 0.090)+= 0.431
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PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
Total of 2 streams to confluence:
Flow rates before confluence point:
0.422 0.090
Maximum flow rates at confluence using above data:
0.500 0.431
Area of streams before confluence:
0.090 0.018
Results of confluence:
Total flow rate = 0.500(CFS)
Time of concentration = 6.373 mm.
Effective stream area after confluence = 0.108(Ac.)
+++++++.+++++++++++++++++.++++++++++++++++.+++++++++++++++++++++++++++
Process from Point/Station 2.032 to Point/Station 2.042
PIPEFLOW TRAVEL TIME (Program estimated size)
Upstream point/station elevation = 132.280(Ft.)
Downstream point/station elevation = 129.390(Ft.)
Pipe length = 54.00(Ft.) Manning's N-0.013
No. of pipes = I Required pipe flow = 0.500(CFS)
Nearest computed pipe diameter = 6.00(ln.)
Calculated individual pipe flow = 0.500(CFS)
Normal flow depth in pipe = 2.58(In.)
Flow top width inside pipe = 5.94(In.)
Critical Depth = 4.33(In.)
Pipe flow velocity = 6.18(Ft/s)
Travel time through pipe = 0.15 mm.
Time of concentration (TC) = 6.52 mm.
Process from Point/Station 2.032 to Point/Station 2.042
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.108(Ac.)
Runoff from this stream = 0.500(CFS)
Time of concentration = 6.52 mm.
Rainfall intensity = 6.217(ln/Hr)
Process from Point/Station 2.040 to Point/Station 2.041
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Masson and Associates, Inc. 6/4/2009
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Sub-Area C Value = 0.690
Initial subarea total flow distance = 65.000(Ft.)
Highest elevation = 157.900(Ft.)
Lowest elevation = 157.500(Ft.)
Elevation difference = 0.400(Ft.) Slope = 0.615 %
USER ENTRY OF INITIAL AREA TIME OF CONCENTRATION
Time of Concentration = 5.00 minutes
Rainfall intensity (I) = 7.377(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.305(CFS)
Total initial stream area = 0.060(Ac.)
PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
U Process from Point/Station 2.041 to Point/Station 2.042
IRREGULAR CHANNEL FLOW TRAVEL TIME
I Estimated mean flow rate at midpoint of channel = 0.33 1 (CFS)
Depth of flow = 0.495(Ft.), Average velocity = 0.452(Ft/s)
Irregular Channel Data
I Information entered for subchannel number I
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.67
I 2 2.00 0.00
3 4.00 0.67
Manning's 'N' friction factor = 0.250
I Sub-Channel flow = 0.331(CFS)
flow top width = 2.955(Ft.)
velocity= 0.452(Ft/s)
area = 0.731(Sq.Ft)
Froude number = 0.160
Upstream point elevation = 133.600(Ft.)
Downstream point elevation= 132.000(Ft.) I Flow length = 40.000(Ft.)
Travel time = 1.47 mm.
U
Time of concentration = 6.47 mm.
Depth of flow = 0.495(Ft.)
Average velocity = 0.452(Ft/s)
Total irregular channel flow = 0.331(CFS)
Irregular channel normal depth above invert elev. = 0.495(Ft.) I Average velocity of channel(s) = 0.452(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
I Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL I (24.0 DU/A or Less
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
I The area added to the existing stream causes a
U a lower flow rate of Q = 0.302(CFS)
therefore the upstream flow rate of Q = 0.305(CFS) is being used
Rainfall intensity = 6.245(ln/Hr) for a 100.0 year storm
Masson and Associates, Inc. 6/4/2009
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Effective runoff coefficient used for total area
(Q=KClA) is C = 0.690 CA = 0.048
Subarea runoff= 0.000(CFS) for 0.010(Ac.)
Total runoff = 0.305(CFS) Total area = 0.070(Ac.)
Depth of flow = 0.480(Ft.), Average velocity = 0.443(Ftls)
PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
Process from Point/Station 2.041 to Point/Station 2.042
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: I in normal stream number 2
Stream flow area = 0.070(Ac.)
Runoff from this stream = 0.305(CFS)
Time of concentration = 6.47 mm.
Rainfall intensity = 6.245(In/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (mm) (In/Hr)
0.500 6.52 6.217 I i
2 0.305 6.47 6.245
Qmax(1) =
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1.000* 1.000* 0.500)+
0.996 * 1.000 * 0.305) + = 0.804
Qmax(2) =
1.000* 0.993* 0.500)+
I 1.000* 1.000* 0.305)+= 0.802
Total of 2 streams to confluence:
I Flow rates before confluence point:
0.500 0.305
Maximum flow rates at confluence using above data:
0.804 0.802
Area of streams before confluence: I 0.108 0.070
Results of confluence:
Total flow rate = 0.804(CFS) I Time of concentration = 6.519 mm.
Effective stream area after confluence = 0.178(Ac.)
Process from Point/Station 2.042 to Point/Station 2.052
PIP EFLOW TRAVEL TIME (Program estimated size)
Upstream point/station elevation = 129.390(Ft.)
Downstream point/station elevation = 128.270(Ft.)
Pipe length = 30.00(Ft.) Mannings N = 0.013
No. of pipes = 1 Required pipe flow = 0.804(CFS)
Nearest computed pipe diameter = 6.00(ln.)
Calculated individual pipe flow = 0.804(CFS)
Normal flow depth in pipe = 3.85(ln.)
Flow top width inside pipe = 5.75(In.)
Critical Depth = 5.34(ln.)
Pipe flow velocity = 6.05(Ft/s)
Travel time through pipe = 0.08 mm.
Masson and Associates, Inc. 6/4/2009
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I PN 0040
LA COSTA VIEWS HOMES
I Time of concentration (TC) = 6.60 min.
LOTS 406-407
+++.++.++++.++++++++++++.+++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.042 to Point/Station 2.052
CONFLUENCE OF MINOR STREAMS
Along Main Stream number I in normal stream number 1
Stream flow area = 0.178(Ac.)
Runoff from this stream = 0.804(CFS)
Time of concentration = 6.60 mm.
Rainfall intensity = 6.167(In/Hr)
+++++++++++++++++++++++++++++++++++++++++++++++++-4-++++++++++++++++++++
Process from Point/Station 2.050 to Point/Station 2.051
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000 I Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL I (24.0 DU/A or Less
Impervious value, Ai = 0.650
I Sub-Area C Value = 0.690
Initial subarea total flow distance = 64.000(Ft.)
Highest elevation = 157.900(Ft.)
Lowest elevation = 157.500(Ft.)
Elevation difference = 0.400(Ft.) Slope = 0.625 % I USER ENTRY OF INITIAL AREA TIME OF CONCENTRATION
Time of Concentration = 5.00 minutes
I Rainfall intensity (I) = 7.377(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.356(CFS)
Total initial stream area = 0.070(Ac.)
Process from Point/Station 2.051 to Point/Station 2.052
IRREGULAR CHANNEL FLOW TRAVEL TIME
Estimated mean flow rate at midpoint of channel = 0.433(CFS)
Depth of flow = 0.539(Ft.), Average velocity = 0.498(Ft/s)
Irregular Channel Data
Information entered for subchannel number I
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.67
2 2.00 0.00
3 4.00 0.67
Manning's 'N' friction factor = 0.250
Sub-Channel flow = 0.433(CFS)
flow top width = 3.219(Ft.)
velocity= 0.498(Ft/s)
area = 0.868(Sq.Ft)
Froude number = 0.169
Masson and Associates, Inc. 6/4/2009
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PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
Upstream point elevation = 132.000(Ft.)
Downstream point elevation = 130.700(Ft.)
Flow length = 30.000(Ft.)
Travel time = 1.00 mm.
Time of concentration = 6.00 mm.
Depth of flow = 0.539(Ft.)
Average velocity = 0.498(Ftls)
Total irregular channel flow = 0.433(CFS)
Irregular channel normal depth above invert elev. = 0.539(Ft.)
Average velocity of channel(s) = 0.498(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/Aor Less
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Rainfall intensity = 6.557(InIHr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.690 CA = 0.069
Subarea runoff = 0.096(CFS) for 0.030(Ac.)
Total runoff= 0.452(CFS) Total area = 0.100(Ac.)
Depth of flow = 0.548(Ft.), Average velocity = 0.504(Ftls)
++++++++++++++++++++++++++++++++++++++++++-1-+++++++++++++++++++++++++++
Process from Point/Station 2.051 to Point/Station 2.052
CONFLUENCE OF MINOR STREAMS
I Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.100(Ac.)
Runoff from this stream = 0.452(CFS)
Time of concentration = 6.00 mm.
Rainfall intensity = 6.557(In/Hr) I Summary of stream data:
Stream Flow rate TC Rainfall Intensity I No. (CFS) (mm) (In/Hr)
1 0.804 6.60 6.167
2 0.452 6.00 6.557 I Qmax(1) =
1.000* 1.000* 0.804)4-
0.941 * 1.000 * 0.452) + = 1.230
I Qmax(2) =
1.000 * 0.909 * 0.804) +
1.000 * 1.000 * 0.452) + = 1.184
Total of 2 streams to confluence:
Flow rates before confluence point:
0.804 0.452
I Maximum flow rates at confluence using above data:
1.230 1.184
Area of streams before confluence:
I 0.178 0.100
Masson and Associates, Inc. 6/4/2009
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I Results of confluence:
Total flow rate = 1 .230(CFS)
Time of concentration = 6.602 mm.
Effective stream area after confluence = 0.278(Ac.)
PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
Process from Point/Station 2.052 to Point/Station 2.062
PIPEFLOW TRAVEL TIME (User specified size)
Upstream point/station elevation = 128.270(Ft.)
Downstream point/station elevation = 126.700(Ft.)
Pipe length = 75.00(Ft.) Mannings N = 0.013
No. of pipes = 1 Required pipe flow = 1 .230(CFS)
Given pipe size = 12.00(ln.)
Calculated individual pipe flow = 1 .230(CFS)
Normal flow depth in pipe = 3.99(In.)
Flow top width inside pipe = 11.31(In.)
Critical Depth = 5.62(ln.)
Pipe flow velocity = 5.39(Ft/s)
Travel time through pipe = 0.23 mm.
Time of concentration (TC) = 6.83 mm.
Process from Point/Station 2.052 to Point/Station 2.062
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number I
Stream flow area = 0.278(Ac.)
Runoff from this stream = 1 .230(CFS)
Time of concentration = 6.83 mm.
Rainfall intensity = 6.031(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.+
Process from Point/Station 2.060 to Point/Station 2.061
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 56.000(Ft.)
Highest elevation = 157.900(Ft.)
Lowest elevation = 157.500(Ft.)
Elevation difference = 0.400(Ft.) Slope = 0.714%
USER ENTRY OF INITIAL AREA TIME OF CONCENTRATION
Time of Concentration = 5.00 minutes
Rainfall intensity (I) = 7.377(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.458(CFS)
Total initial stream area = 0.090(Ac.)
Masson and Associates, Inc. 6/4/2009
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I PN 0040
LA COSTA VIEWS HOMES
[1 Process from Point/Station 2.061 to Point/Station 2.062
LOTS 406-407
IRREGULAR CHANNEL FLOW TRAVEL TIME
Estimated mean flow rate at midpoint of channel = 0.534(CFS)
Depth of flow = 0.551(Ft.), Average velocity = 0.590(Ft/s)
Irregular Channel Data
Information entered for subchannel number 1:
Point number X coordinate 'Y' coordinate
1 0.00 0.67
2 2.00 0.00
3 4.00 0.67
Mannings 'N' friction factor = 0.250
Sub-Channel flow = 0.534(CFS)
flow top width = 3.290(Ft.)
velocity= 0.590(Ft/s)
area = 0.906(Sq.Ft)
Froude number= 0.198
Upstream point elevation = 130.000(Ft.)
Downstream point elevation = 126.700(Ft.)
Flow length = 56.000(Ft.)
Travel time = 1.58 mm.
Time of concentration = 6.58 mm.
Depth of flow = 0.551(Ft.)
Average velocity = 0.590(Ft/s)
Total irregular channel flow = 0.534(CFS)
Irregular channel normal depth above invert elev. = 0.551(Ft.)
Average velocity of channel(s) = 0.590(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Rainfall intensity = 6.178(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KClA) is C = 0.690 CA = 0.083
Subarea runoff = 0.053(CFS) for 0.030(Ac.)
Total runoff= 0.512(CFS) Total area = 0.120(Ac.)
Depth of flow = 0.542(Ft.), Average velocity = 0.583(Ffis)
Process from Point/Station 2.061 to Point/Station 2.062
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.120(Ac.)
Runoff from this stream = 0.512(CFS)
Time of concentration = 6.58 mm.
Rainfall intensity = 6.178(In/Hr)
Summary of stream data:
Masson and Associates, Inc. 6/4/2009
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PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
Stream Flow rate TC Rainfall Intensity
No. (CFS) (mm) (In/Hr)
1 1.230 6.83 6.031
2 0.512 6.58 6.178
Qmax(1) =
1.000 * 1.000 * 1.230) +
0.976* 1.000* 0.512)+= 1.729
Qmax(2) =
1.000 * 0.963 * 1.230) +
1.000* 1.000* 0.512)+= 1.696
Total of 2 streams to confluence:
Flow rates before confluence point:
1.230 0.512
Maximum flow rates at confluence using above data:
1.729 1.696
Area of streams before confluence:
0.278 0.120
Results of confluence:
Total flow rate = 1 .729(CFS)
Time of concentration = 6.834 mm.
Effective stream area after confluence = 0.398(Ac.)
Process from Point/Station 2.062 to Point/Station 2.072
IRREGULAR CHANNEL FLOW TRAVEL TIME
!!Warning: Water is above left or right bank elevations
!Warning: Water is above left or right bank elevations
!!Warning: Water is above left or right bank elevations
Estimated mean flow rate at midpoint of channel = 1.778(CFS)
Depth of flow = 1.036(Ft.), Average velocity = 0.418(Ft/s)
!!Warning: Water is above left or right bank elevations
Irregular Channel Data
Information entered for subchannel number 1:
Point number 'X' coordinate 'Y' coordinate
1 0.00 1.00
2 3.00 0.00
3 4.00 0.00
4 7.00 1.00
Mannings 'N' friction factor = 0.250
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Sub-Channel flow = 1.778(CFS)
flow top width = 7.000(Ft.)
velocity= 0.418(Ft/s)
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, area = 4.250(Sq.Ft)
Froude number = 0.095
Upstream point elevation = 126.700(Ft.)
Downstream point elevation = 125.400(Ft.)
Flow length = 127.000(Ft.)
Travel time = 5.06 mm.
Time of concentration = 11.89 mm.
Masson and Associates, Inc. 6/4/2009
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Depth of flow = 1.036(Ft.)
Average velocity = 0.418(Ftls)
Total irregular channel flow = 1 .778(CFS)
Irregular channel normal depth above invert elev. = 1 .036(Ft.)
Average velocity of channel(s) = 0.418(Ft/s)
'!Warning: Water is above left or right bank elevations
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DU/Aor Less
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
The area added to the existing stream causes a
a lower flow rate of 0= 1 .295(CFS)
therefore the upstream flow rate of Q = I .729(CFS) is being used
Rainfall intensity = 4.219(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KClA) is C = 0.629 CA = 0.307
Subarea runoff = 0.000(CFS) for 0.090(Ac.)
Total runoff = 1 .729(CFS) Total area = 0.488(Ac.)
Depth of flow = 1.026(Ft.), Average velocity = 0.414(Ft/s)
!!Warning: Water is above left or right bank elevations
PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.062 to Point/Station 2.072
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: I in normal stream number 1
Stream flow area = 0.488(Ac.)
Runoff from this stream = 1 .729(CFS)
Time of concentration = 11.89 mm. * Rainfall intensity = 4.219(ln/Hr)
++++++++++++++++++++++++++++++.++++.++.+++++++++++++++++++++++++++++++
Process from Point/Station 2.081 to Point/Station 2.082
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 58.000(Ft.)
Highest elevation= 136.800(Ft.)
Lowest elevation= 126.000(Ft.)
Elevation difference = 10.800(Ft.) Slope = 18.621 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 100.00 (Ft)
for the top area slope value of 18.62 %, in a development type of
24.0 DU/AorLess
Masson and Associates, Inc. 6/4/2009
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In Accordance With Figure 3-3
Initial Area Time of Concentration = 2.78 minutes
TC = [1.8*(1 .1 _C)*distance(Ft.).5)/(% slope A( 1/3)]
TC = [1.8*(1.10.6900)*( 100.000A.5)/( 18.621A(1/3)]= 2.78
Calculated IC of 2.784 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 7.377(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.204(CFS)
Total initial stream area = 0.040(Ac.)
PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++.++.+++++++++
Process from Point/Station 2.082 to Point/Station 2.071
PIPEFLOW TRAVEL TIME (User specified size)
Upstream point/station elevation = 125.910(Ft.)
Downstream point/station elevation = 125.670(Ft)
Pipe length = 24.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 0.204(CFS)
Given pipe size = 12.00(ln.)
Calculated individual pipe flow = 0.204(CFS)
Normal flow depth in pipe = 1.95(ln.)
Flow top width inside pipe = 8.85(ln.)
Critical Depth = 2.21 (In.)
Pipe flow velocity = 2.46(Ft/s)
Travel time through pipe = 0.16 mm.
Time of concentration (TC) = 2.95 mm.
Process from Point/Station 2.071 to Point/Station 2.072
PIPEFLOW TRAVEL TIME (Program estimated size)
Upstream point/station elevation = 125.670(Ft.)
Downstream point/station elevation = 125.400(Ft.)
Pipe length = 27.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 0.204(CFS)
Nearest computed pipe diameter = 6.00(ln.)
Calculated individual pipe flow = 0.204(CFS)
Normal flow depth in pipe = 250(In..)
Flow top width inside pipe = 5.92(ln.)
Critical Depth = 2.71 (In.)
Pipe flow velocity = 2.63(Ft/s)
Travel time through pipe 0.17 mm.
Time of concentration (TC) = 3.12 mm.
++++++++++.+++.++.++.++++++++.++++.++++++.++.+++++++++++++++++++++++++
Process from Point/Station 2.071 to Point/Station 2.072
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: I in normal stream number 2
Stream flow area = 0.040(Ac.)
Runoff from this stream = 0.204(CFS)
Time of concentration = 3.12 mm.
Rainfall intensity = 7.377(ln/Hr)
Summary of stream data:
Masson and Associates, Inc. 6/4/2009
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I PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
Stream Flow rate TC Rainfall Intensity
No. (CFS) (mm) (In/Hr)
I I 1.729 11.89 4.219
2 0.204 3.12 7.377
Qmax(1) =
I 1.000 1.000* I.729)+
0.572* 1.000* 0.204)+= 1.845
Qmax(2) =
I 1.000 * 0.262 * 1.729) +
1.000 * 1.000 * 0.204) + = 0.657
Total of 2 streams to confluence:
Flow rates before confluence point: I 1.729 0.204
Maximum flow rates at confluence using above data:
I 1.845 0.657
Area of streams before confluence:
0.488 0.040
Results of confluence:
Total flow rate= 1.845(CFS) I Time of concentration = 11.893 mm.
Effective stream area after confluence = 0.528(Ac.)
++++++++++++++++++++++++++++++++++++++++4-+++++++++++++++++++++++++++++
Process from Point/Station 2.072 to Point/Station 2.073
PIPEFLOW TRAVEL TIME (Program estimated size)
Upstream point/station elevation = 125.400(Ft.)
Downstream point/station elevation = 125.300(Ft.)
Pipe length = 11.00(Ft.) Manning's N = 0.013
No. of pipes = I Required pipe flow 1.845(CFS)
Nearest computed pipe diameter = 12.00(ln.)
Calculated individual pipe flow = 1.845(CFS)
Normal flow depth in pipe = 6.30(ln.)
Flow top width inside pipe= 11 .98(ln.)
Critical Depth = 6.95(ln.)
Pipe flow velocity = 4.41(Ft/s)
Travel time through pipe = 0.04 mm.
Time of concentration (TC) = 11.93 mm.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.+++++.++
Process from Point/Station 2.073 to Point/Station 2.101
IRREGULAR CHANNEL FLOW TRAVEL TIME
Depth of flow = 0.129(Ft.), Average velocity= 4.779(Ft/s)
Irregular Channel Data
Information entered for subchannel number I
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.25
2 0.00 0.00
3 3.00 0.00
4 3.00 0.25
Manning's 'N' friction factor = 0.016
Masson and Associates, Inc. 6/4/2009
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I PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
Sub-Channel flow = 1.846(CFS)
flow top width = 3.000(Ft.)
velocity= 4.779(Ft/s)
area = 0.386(Sq.Ft)
Froude number = 2.347
I Upstream point elevation = 125.300(Ft.)
Downstream point elevation = 124.800(Ft.)
Flow length = 11 .000(Ft.)
I Travel time = 0.04 mm.
Time of concentration = 11.97 mm.
Depth of flow = 0.129(Ft.)
Average velocity = 4.779(Ft/s)
I Total irregular channel flow = I .845(CFS)
Irregular channel normal depth above invert elev. = 0.129(Ft.)
Average velocity of channel(s) = 4.779(Ft/s)
++++++++++++.-I-+++++++++++.+++++++++++++++++++++++++.+++.++++++++++++++
Process from Point/Station 2.073 to Point/Station 2.101
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number I
Stream flow area = 0.528(Ac.)
Runoff from this stream = 1 .845(CFS)
Time of concentration = 11.97 mm.
Rainfall intensity = 4.200(In/Hr)
Process from Point/Station 2.091 to Point/Station 2.092
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 99.000(Ft.)
Highest elevation = 140.000(Ft.)
Lowest elevation = 138.500(Ft.)
Elevation difference = 1.500(Ft.) Slope = 1.515 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 75.00 (Ft)
for the top area slope value of 1.51 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.56 minutes
TC = [1 .8*(1 .1 _C)*distance(Ft.).5)/(% slope '(1/3)]
TC = [1.8*(1.10.6900)*( 75.000A.5)/( 1.515A(1/3)J= 5.56
The initial area total distance of 99.00 (Ft.) entered leaves a
remaining distance of 24.00 (Ft.)
Using Figure 3-4, the travel time for this distance is 0.45 minutes
for a distance of 24.00 (Ft.) and a slope of 1.51 %
with an elevation difference of 0.36(Ft.) from the end of the top area
Masson and Associates, Inc. 6/4/2009
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Tt = [11 .9*Iength(Mi)A3)/(elevation change(Ft.))]'.385 *60(min/hr)
= 0.453 Minutes
Tt=[(1 1 9*00045A3)/( 0.36)]A.385= 0.45
Total initial area Ti = 5.56 minutes from Figure 3-3 formula plus
0.45 minutes from the Figure 3-4 formula = 6.02 minutes
Rainfall intensity (I) = 6.546(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff= 1.129(CFS)
Total initial stream area = 0.250(Ac.)
PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
Process from Point/Station 2.092 to Point/Station 2.101
IRREGULAR CHANNEL FLOW TRAVEL TIME
Estimated mean flow rate at midpoint of channel = I .559(CFS)
Depth of flow = 0.254(Ft.), Average velocity = 3.987(Ft/s)
Irregular Channel Data
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Information entered for subchannel number 1
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.90
2 31.00 0.14
3 31.65 0.00
4 31.75 0.50
Manning's 'N' friction factor = 0.016
Sub-Channel flow = I .559(CFS)
flow top width = 5.350(Ft.)
velocity= 3.987(Ft/s)
area= 0.391(Sq.Ft)
Froude number = 2.599
Upstream point elevation = 138.500(Ft.)
Downstream point elevation = 124.800(Ft.)
Flow length = 215.000(Ft.)
Travel time = 0.90 mm.
Time of concentration = 6.92 mm.
Depth of flow = 0.254(Ft.)
Average velocity = 3.987(Ft/s)
Total irregular channel flow = 1 .559(CFS)
Irregular channel normal depth above invert elev. = 0.254(Ft.)
Average velocity of channel(s) = 3.987(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Rainfall intensity = 5.984(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.690 CA = 0.317
Subarea runoff = 0.770(CFS) for 0.210(Ac.)
Total runoff = 1.899(CFS) Total area = 0.460(Ac.)
Masson and Associates, Inc. 6/4/2009
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PN 0040
LA COSTA VIEWS HOMES
LOTS 406-407
Depth of flow = 0.265(Ft.), Average velocity = 4.175(Ftls)
Process from Point/Station 2.092 to Point/Station 2.101
CONFLUENCE OF MINOR STREAMS
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.460(Ac.)
Runoff from this stream = 1 .899(CFS)
Time of concentration = 6.92 mm.
Rainfall intensity = 5.984(InIHr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (mm) (In/Hr)
1 1.845 11.97 4.200
2 1.899 6.92 5.984
Qmax(1) =
1.000* 1.000* 1.845)+
0.702 * 1.000 * 1.899) + = 3.179
Qmax(2) =
1.000 * 0.578 * 1.845) +
1.000* 1.000* 1.899)+= 2.965
Total of 2 streams to confluence:
Flow rates before confluence point:
1.845 1.899
Maximum flow rates at confluence using above data:
3.179 2.965
Area of streams before confluence:
0.528 0.460
Results of confluence:
Total flow rate = 3.179(CFS)
Time of concentration = 11.973 mm.
Effective stream area after confluence = 0.988(Ac.)
End of computations, total study area = 0.988 (Ac.)
Masson and Associates, Inc. 6/4/2009
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SCALE IN FEET GRAPHIC SCALE
DATE: Jun 04, 09 2:53pm by.slee
FILE: I: \DWG\00\0040\Reports\Hydrology\0040-pre-Dev- 406-407. dwg
MASSON & ASSOCIATES, INC. PLANNING v ENGINEERING v SURVEYING
200 E. WASHINGTON AVE. v SUITE 200' ESCONDIDO 'CA 92025-1816
TEL (760) 741-3570 v FAX (760) 741-1786 v www.masson-assoc.com
N
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PRE-DEVELOPMENT HYDROLOGY MAP - LOT 4067 407
LA COSTA VIEW HOMES
CT 08-01 I PUD 08-01 I HDP 08-01
FN 0040 DAM 06-04-09
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