HomeMy WebLinkAboutMS 07-01; HAIG/SCOTT SUBDIVISION; DRAINAGE REPORT; 2007-06-11DRAINAGE REPORT
FOR
BERGER RESIDENCE
APN 205 - 060 - 07
PREPARED FOR
Richard Berger
2331 Dana Court
Carlsbad, CA 92008
PREPARED BY
Robert 0. Sukup
4322 Sea Bright Place
Carlsbad, CA 92008
=3302
June 11, 2007 \\ E4.31I0
II
The proposed project is to construct a new single family house on a vacant lot
on the east side of Highland Drive. The entire lot is about .39 acres. The main
concern is the eastern portion of the lot that flows downhill to the east. Per the
attached calculations it shows the flow after development is projected to
increase by about .51 cfs [ .23 cfs to .74 cfs] for the 100 year storm. Previous
development below this project anticipated future construction and installed a
concrete swale along their property line to collect this runoff.
The existing concrete swale will handle the projected flow and no flooding of the
downstream residence will occur.
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San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 6of26
Table 3-1
RUNOFF COEFFICIENTS FOR URBAN AREAS
Land Use Runoff Coefficient "C"
V0 IMPER. A (B) - C 1)
0.20 0.30 0.35
10 027 0.32 0.36 0.41
20 0.34 0.38 0.42 0.46
25 0.38 0.41 0.45 0.49
30 0.41 0.45 0.48 0.52
(DO POST 0.48 ('i30ST 0.54 0.57
45 0.52 0.54 0.57 0.60
50 0.55 0.58 0.60 0.63
65 0.66 0.67 0.69 0.71
80 0.76 0.77 0.8 0.79
80 0.76 0.77 0,78 0.79
85 0.80 0.80 0.81 0.82
90 0.83 0.84 0.84 0.85
90 0.83 0.84 0.84 0.85
95 0.87 0.87 0.87 0.87
NRCS Elements
Undisturbed Natural Terrain (Natural) Permanent Open Space
Low Density Residential (LDR) Residential, 1.0 DU/A or less
Low Density Residential (LDR) Residential, 2.0 DU/A or less
Low Density Residential (LDR) Residential, 2.9 DU/A or less
Medium Density Residential (MDR) Residential, 4.3 DU/A or less
Medium Density Residential (MDR) Residential, 7.3 DU/A or less
Medium Density Residential (MDR) Residential, 10.9 DU/A or less
Medium Density Residential (MDR.) Residential, 14.5 DU/A or less
High Density Residential (HDR) Residential, 24.0 DU/A or less
High Density Residential (HDR) Residential, 43.0 DU/A or less
Commercial/Industrial (N. Corn) Neighborhood Commercial
Commercial/Industrial ((3. Corn) General Cc,rmnercial
Commercial/Industrial (O.P. Corn) Office Professional/Commercial
Commercial/Industrial (Limited I.) Limited Industrial
Commercial/industrial (General I.)
*The values associated with 0% impervious may be used for direct calculation of the runoff coefficient as described in Section 3.1.2 (representing the pervious runoff
coefficient, Cp, for the soil type), or fbr areas that Will remain undisturbed in perpetuity. Justification must be given that the area will remain natural forever (e.g., 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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EXAMPLE:
Given: Watercourse Distance (D) = 70 Feet
Slope (s) =1.3%
Runoff Coefficient (C) = 0.41
Overland Flow Time (T) = 9.5 Minutes
T= 1.8 (1.1-C) V13
SOURCE: Airport Drainage, Federal Aviation Administration, 1965
Rational Formula - Overland Time of Flow Nomograph
FIGURE
3w3
13RCd-R Th.
Hsi oRcoray'
—1000
900
Boo 2 120
100
600\ 90
—50O 90
\
—400 \ TO
—300 50
—200 40
L
Miles Feet
'S
30
—100
4000 20
• . ••.-l••*%%. 18
• -1--- 3000 16
0.5—I —50 'S 14
—40
\\ I__2000 12
• . l—_1800
I-1600 10
I-1400 g
1200 8
—20 . I—joan 7 l-900
I-800 6
.• —700
koo 5
—500
EQUATION
/11.9L3\0.385
1Feet
Tc = Time of concentration (hours)
L = Watercourse Distance (miles)
4000 AE = Change in elevation along
1- effective slope tine (See Figure 35) (feet)
I_3000 * Tc
I... Hours( Minutes
2000 -240
3-1 180
-- -400
300 —3 ç3Te I Ilk
—200
LE LZ 10 O L Ic
SOURCE: California Division of Highways (1941) and Kirpich (1940) - -
FIGURE
Nomograph for Determination of
Time of Concentration (Tc) or Travel Time (Tt) for Natural V#tersheds 3.4
.-T ... ........ I'll
E
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t. A i... I . 3 0 3 Miles
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