HomeMy WebLinkAboutWPO201800027 Calculations 2020-05-11MARTHA JEFFERSON HOSPITAL APARTMENTS
STORMWATER MANAGEMENT CALCULATIONS PACKET
(AMENDMENT #1 TO WPO 201800027)
Date of Calculations
APRIL 22, 2020
PREPARED BY:
COLLINS ENGINEERING
200 GARRETT STREET, SUITE K
CHARLOTTESVILLE, VA 22902
434.293.3719 PH
434.293.2813 FX
www.collins-engineering.com
SCS TR-55 Calculations
The proposed 'Martha Jefferson Hospital Presidio Apartments' final site plan
(SDP201900075) is in general conformance with this project's original VSMP
approval (WPO 201800027) with one major exception. Subarea B was modified
and no longer proposes an underground detention system. To compensate for
this removal, the approved dry detention cell has been enlarged with this
amendment and calculations have been provided showing continued stormwater
quantity compliance for subarea B.
APPROVED Subarea A Summary:
Subarea A ( ) drains to a Level II wet pond that provides stormwater quality and quantity treatment.
The 1-, 2-, 10- and 100-year design storm routings can be viewed in the ✓IJH Apartments- Level 11 Wet Pond
documents.
Channel protection for subarea A is met through 9VAC25-870-66, subsection B.3.a. The limits of the channel
protection analysis end at the wet pond since subdivision 3 of the aforementioned subsection is utilized.
Flood protection is met through 9VAC25-870-66, subsection C.2.b. The limits of the flood protection analysis
ends at the wet pond's outfall since section C.2.b is met.
AMENDED Subarea B Summary:
Subarea B ( ) drains to a dry detention cell that provides stormwater quantity treatment. The 1-, 2-, 10-
and 100-year design storm routings can be viewed in the MJH Apartments- Detention Cell Routings
documents.
Channel protection for subarea B is met through 9VAC25-870-66, subsection B.3.a. The limits of the channel
protection analysis end at the dry detention cell since subdivision 3 of the aforementioned subsection is
utilized. Flood protection is met through 9VAC25-870-66, subsection C.2.a. The limits of the flood protection
analysis ends at the dry detention cell's outfall, where the stormwater conveyance system enters a mapped
floodplain.
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APPROVED Soils Table (Source: NRCS Web Soil Survey Online Database)
Albemarle County. Virginia (VA0031
Albemarle County, Virginia
(VA003)
Map
Unit
Map Unit Name
Percent of
A0I
symbol
23C
Davidson clay
1.811/0
loam, 7 to 15
percent slopes
59❑
Myersville very
8.811/0
stony silt loam,
15to25
percent slopes
71❑
Rabun clay
0.6%
loam, 15 to 25
percent slopes
72C3
Rabun clay, 7
24.1%
to 15 percent
slopes, severely
eroded
72D3
Rabun clay, 15
18.60/a
to 25 percent
slopes, severely
eroded
73❑
Rabun very
18.60/0
stony clay
loam, 15 to 25
percent slopes
73E
Rabun very
26.70/6
stony clay
loam, 25 to 45
percent slopes
89B
Unison silt
0.40/6
loam, 2 to 7
percent slopes
W
Water
0.30/6
Totals for Area of
100.00/0
Interest
Note: The NRCS web soil survey has catorgized this parcel's soil types as predominantley having hydrologic
group types of B.
APPROVED Precipitation Data
(Source: NOAA's National Weather Service, Hydrometerorological Design Studies Center, Atlas 14
Point Precipitation Frequency Estimates)
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POINT PRECIPITATION FREQUENCY (PF) ESTIMATES
WITH WX3 CONFIDENCE INTERVALS AND SUPPLEMENTARY INFORMATION
NOAA Atlas 14, Volume 2, Version 3
e
d
PDS-based precipitation frequency estimates with 90% confidence intervals (in inches)'
Average recurrence interval (years)
Duration 500
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7 2 5 7D 25 50 100 2D0 10D0
24-hr 3.02 3.65 d.66 5.52 6.78 7.87 9.07 70.4 12.4 94.7
(2 71-3 39) [3 28-4.10] (4.18-5 24) (4 92-6 18) [6 N-7 57] (6 93A 76) (7 92-10 1 } [8 98-713] [10 5-73 7] (71 8-15 6}
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U.S. Department of Agriculture
Natural Resources Conservation Service
TR 55 Worksheet 3: Time of Concentration (Tc) or Travel Time (Tt)
Project: Martha Jefferson Hospital Apartments
Location: Peter Jefferson Parkway
Check One: Present X Developed X
Check One: Tc X Tt
Segment ID
Sheet Flow: (Applicable to Tc only)
Designed By: FGM, PE
Checked By: SRC, PE
Through subarea n/a
Date:
Date:
FL-ENG-21A
06/04
4/22/2020
n /-)-) /-)n-in
APPROVED
APPRO,
AMENDED
DA A
DA B
DAP
DA B
(Pre-Dev.)
(Pre-Dev.)
(Post-Dev.)
1 Surface description (Table 3-1) Dense Grass Dense Grass
2 Manning's roughness coeff., n (Table 3-1 0.24 0.24
3 Flow length, L (total L < 100) (ft) 100 100
4 Two-year 24-hour rainfall, PZ (in.) 3.7 3.7
5 Land slope, s (ft/ft) 0.19 0.16
6 Compute Tt = [0.007(n*L)08] / PZoS s°4 0.09 0.10
Shallow Concentrated Flow:
7 Surface description (paved or unpaved)
Unpaved
Unpaved
8 Flow Length, L (ft)
775
635
9 Watercourse slope, s (ft/ft)
0.108
0.110
10 Average velocity, V (Figure 3-1) (ft/s)
5.2
5.3
11 Tt = L / 3600*V
0.04
0.03
Channel Flow:
12 Cross sectional flow area, a (ft)
13 Wetted perimeter, PN, (ft)
14 Hydraulic radius, r = a/PW (ft)
15 Channel Slope, s (ft/ft)
16 Manning's Roughness Coeff, n
17 V= [ 1.49r2/3so 5 ) / n
18 Flow length, L (ft)
19 Tt= L / 3600*V
20 Watershed or subarea Tc or Tt
(Add Tt in steps 6, 11 and 19) 0.10
(AMENDED)
Note: The most conservative post -development SCS Tc is 0.10 hrs.
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WATERSHED SUMMARY
APPROVED Subarea A
AMENDED Subarea B
AMENDED DA B (Post-Dev.
1-year Flow, 2-year Flow, 10-year Flow,
CN Area, ac. cfs cfs cfs
CN Area, ac. 1-year Flow, 2-year Flow, 10-year Flow,
cfs cfs cfs
83.3 5.69 0.30 4.81 20.86
i otai Area Summary
Pre -Development DA A & B 11.71 ac.
Post -Development DA A & B 11.71 ac.
9 VAC 25-870-66 APPROVED Subarea A
Section B: Channel Protection
"Concentrated stormwater flow shall be released into a stormwater conveyance system and
shall meet the criteria in subdivision 1, 2 or 3 of this subsection..."
Section B.1: Manmade stormwater conveyance systems
"When stormwater from a development is discharged to a manmade stormwater conveyance
system, following the land -disturbing activity, either..." a. or b. shall be met:
Section 13.1.1b.
"The peak discharge requirements for concentrated stormwater flow to natural stormwater
conveyance systems in subdivision 3 of this subsection shall be met."
Section B.3
"When stormwater from a development is discharged to a natural stormwater conveyance
system, the maximum peak flow rate from the one-year 24-hour storm following the land -
disturbing activity shall be calculated either..." a. or b."
Section B.3.a.
In accordance with the following methodology:
Q Developed _< I•F (Q Pre -Developed RV Pre -Developed) RV Developed
Q Allowed _< 1.12 cfs
Q Developed < 0.92 cfs
(From Routings)
Section B.4 Limits of Analysis
Where: Q Pre -Developed -
4.49 cfs
CN Pre -Developed-
64.2
S Pre -Developed -
5.57
RV Pre -Developed -
0.49 In.
CN Post -Developed-
84.4
S Post -Developed -
1.85
RV Post -Developed -
1.56 In.
The analysis terminates at the SWM facility since "...subdivision 3 of this subsection is utiilzed
to shown compliance with the channel protection criteria..."
9 VAC 25-870-66 APPROVED Subarea A
Section C: Flood Protection
"Concentrated stormwater flow shall be released into a stormwater conveyance system and
shall meet one of the following criteria as demonstrated by use of acceptable hydrologic and
hydraulic methodologies:"
Section C.2.b.:
The point of discharge "releases a postdevelopment peak flow rate for the 10-year 24-hour
storm event that is less than the predevelopment peak flow rate from the 10-year 24-hour
storm event. Downstream stormwater conveyance systems do not require any additional
analysis to show compliance with flood protection criteria if this option is utilized."
Section C.3 Limits of Analysis
The analysis terminates at the proposed SWM facility since subsection C.2.b is met.
9 VAC 25-870-66 AMENDED Subarea B
Section B: Channel Protection
"Concentrated stormwater flow shall be released into a stormwater conveyance system and
shall meet the criteria in subdivision 1, 2 or 3 of this subsection..."
Section B.1: Manmade stormwater conveyance systems
"When stormwater from a development is discharged to a manmade stormwater conveyance
system, following the land -disturbing activity, either..." a. or b. shall be met:
Section B.1.b.
"The peak discharge requirements for concentrated stormwater flow to natural stormwater
conveyance systems in subdivision 3 of this subsection shall be met."
Section B.3
"When stormwater from a development is discharged to a natural stormwater conveyance
system, the maximum peak flow rate from the one-year 24-hour storm following the land -
disturbing activity shall be calculated either..." a. or b."
Section B.3.a.
In accordance with the following methodology:
QAllowed _'5- I•F• (Q Pre -Developed RV Pre -Developed) RV Developed
QAllowed < 0.30 cfs Where
(AMENDED)
Q Developed < 0.30 cfs
Q Pre -Developed -
1.55 cfs
CN Pre -Developed-
60.6
S Pre -Developed -
6.50
RV Pre -Developed -
0.36 in.
CN Post -Developed-
83.3
S Post -Developed -
2.01
RV Post -Developed-
1.48 in.
9 VAC 25-870-66 AMENDED Subarea B
Section C: Flood Protection
"Concentrated stormwater flow shall be released into a stormwater conveyance system and
shall meet one of the following criteria as demonstrated by use of acceptable hydrologic and
hydraulic methodologies:"
Section C.2.a.:
The point of discharge (the dry detention cell), "confines the postdevelopment peak flow
rate from the 10-year 24-hour storm event within the stormwater conveyance system to
avoid the localized flooding."
Section C.3.c Limits of Analysis
The flood protection analysis terminates at the site outfall because, "the stormwater
conveyance system enters a mapped floodplain."
APPROVED Level II Wet Pond Calculations
(DA A)
MJH Apartments- Level II Wet Pond Routings
BasinFlow printout
INPUT:
Basin: MJH Apartments- Level II Wet Pond Routings
6 Contour Areas
Elevation(ft)
Area(sf)
Computed Vol.(cy)
376.00
682.00
0.0
378.00
2623.00
114.6
379.00
4712.00
248.6
380.00
8311.00
486.6
382.00
14412.00
1317.9
384.00
20500.00
2604.3
Start_Elevation(ft) 380.00 Vol.(cy)
Page 1
486.62
MJH Apartments- Level II Wet Pond Routings
4 Outlet Structures
Outlet structure 0
Orifice
name: Barrel
area (sf) 4.909
diameter or depth (in) 30.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 372.500
multiple 1
discharge out of riser
Outlet structure 1
Orifice
name: Low -Flow Orifice
area (sf) 0.196
diameter or depth (in) 6.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 380.000
multiple 1
discharge into riser
Outlet structure 2
Weir
name: Riser
diameter (in)
24.000
side angle
0.000
coefficient
3.300
invert (ft)
381.750
multiple
1
discharge
into riser
transition at (ft)
0.608
orifice coef.
0.500
orifice area (sf)
3.142
Outlet structure 3
Weir
name: Emergency Spillway
length (ft)
100.000
side angle
75.960
coefficient
3.300
invert (ft)
382.750
multiple
1
discharge
through dam
Page 2
MJH Apartments- Level II Wet Pond Routings
4 Inflow Hydrographs
Hydrograph 0
SCS
name: 1-yr 24-hr SCS Method Design Storm
Area (acres)
6.020
CN
84.400
Type 2
rainfall, P (in)
3.020
time of conc. (hrs)
0.1000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
11.927
peak time (hrs)
11.917
volume (cy)
1262.762
Hydrograph 1
SCS
name: 2-yr 24-hr SCS Method Design Storm
Area (acres)
6.020
CN
84.400
Type 2
rainfall, P (in)
3.650
time of conc. (hrs)
0.1000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
16.027
peak time (hrs)
11.917
volume (cy)
1696.813
Hydrograph 2
SCS
name: 10-yr 24-hr SCS Method Design Storm
Area (acres)
6.020
CN
84.400
Type 2
rainfall, P (in)
5.520
time of conc. (hrs)
0.1000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
28.952
peak time (hrs)
11.917
volume (cy)
3065.166
Page 3
Hydrograph 3
SCS
name:
Area (acres)
CN
Type
rainfall, P (in)
time of conc. (hrs)
time increment (hrs)
time limit (hrs)
fudge factor
routed
peak flow (cfs)
peak time (hrs)
volume (cy)
MJH Apartments- Level II Wet Pond Routings
100-yr 24-hr SCS Method Design Storm
6.020
84.400
2
OUTPUT:
Routing Method: storage -indication
Hydrograph 0
Routing Summary of Peaks: 1-yr 24-hr SCS Method Design Storm
inflow (cfs) 11.871 at 11.92 (hrs)
discharge (cfs) 0.922 at 12.50 (hrs)
water level (ft) 381.620 at 12.52 (hrs)
storage (cy) 1124.076
Hydrograph 1
Routing Summary of Peaks: 2-yr 24-hr SCS Method Design Storm
inflow (cfs) 15.952 at 11.92 (hrs)
discharge (cfs) 2.854 at 12.14 (hrs)
water level (ft) 381.948 at 12.14 (hrs)
storage (cy) 1290.384
Hydrograph 2
Routing Summary of Peaks: 10-yr 24-hr SCS Method Design Storm
inflow
(cfs)
28.817
at
11.92
(hrs)
discharge
(cfs)
13.232
at
12.06
(hrs)
water level
(ft)
382.659
at
12.06
(hrs)
storage
(cy)
1692.170
Hydrograph 3
Routing Summary
of
Peaks: 100-yr
24-hr
SCS
Method Design Storm
inflow
(cfs)
54.558
at
11.92
(hrs)
discharge
(cfs)
51.778
at
11.94
(hrs)
water level
(ft)
382.979
at
11.94
(hrs)
storage
(cy)
1891.521
Wed Mar 06 10:35:57 EST 2019
Page 4
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AMENDED Dry Detention Cell Routing Calculations
(DA 6)
MJH Apartments- Detention Cell Routings
BasinFlow printout
INPUT:
Basin: MJH Apartments- Detention Cell Routings.txt
5 Contour Areas
Elevation(ft)
Area(sf)
Computed Vol.(cy)
352.00
537.00
0.0
354.00
2282.00
96.9
356.00
4631.00
347.9
358.00
7392.00
789.2
360.00
10557.00
1450.5
Start—Elevation(ft)
4 Outlet Structures
Outlet structure 0
Orifice
352.00 Vol.(cy) 0.00
name: Barrel
area (sf) 3.142
diameter or depth (in) 24.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 350.000
multiple 1
discharge out of riser
Outlet structure 1
Orifice
name: Low -Flow Orifice
area (sf) 0.032
diameter or depth (in) 2.420
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 352.000
multiple 1
discharge into riser
Page 1
MJH Apartments- Detention Cell Routings
Outlet structure 2
Weir
name: Riser
diameter (in)
24.000
side angle
0.000
coefficient
3.300
invert (ft)
357.500
multiple
1
discharge
into riser
transition at (ft)
0.608
orifice coef.
0.500
orifice area (sf)
3.142
Outlet structure 3
Weir
name: Emergency Spillway
length (ft)
50.000
side angle
75.960
coefficient
3.300
invert (ft)
358.660
multiple
1
discharge
through dam
4 Inflow Hydrographs
Hydrograph 0
SCS
name: 1-yr 24-hr SCS Method Design Storm
Area (acres)
5.690
CN
83.300
Type 2
rainfall, P (in)
3.020
time of conc. (hrs)
0.1000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
10.711
peak time (hrs)
11.917
volume (cy)
1133.953
Page 2
Hydrograph 1
SCS
MJH Apartments- Detention Cell Routings
name: 2-yr 24-hr SCS Method Design Storm
Area (acres)
5.690
CN
83.300
Type 2
rainfall, P (in)
3.650
time of conc. (hrs)
0.1000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
14.507
peak time (hrs)
11.917
volume (cy)
1535.863
Hydrograph 2
SCS
name: 10-yr 24-hr SCS Method Design Storm
Area (acres)
5.690
CN
83.300
Type 2
rainfall, P (in)
5.520
time of conc. (hrs)
0.1000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
26.559
peak time (hrs)
11.917
volume (cy)
2811.780
Hydrograph 3
SCS
name: 100-yr 24-hr SCS Method Design Storm
Area (acres)
5.690
CN
83.300
Type 2
rainfall, P (in)
9.070
time of conc. (hrs)
0.1000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
50.835
peak time (hrs)
11.917
volume (cy)
5381.939
Page 3
MJH Apartments- Detention Cell Routings
OUTPUT:
Routing Method: storage -indication
Hydrograph 0
Routing Summary of Peaks
inflow (cfs)
discharge (cfs)
water level (ft)
storage (cy)
Hydrograph 1
Routing Summary of Peaks:
inflow (cfs)
discharge (cfs)
water level (ft)
storage (cy)
1-yr 24-hr SCS Method Design Storm
10.661 at 11.92 (hrs)
0.302 at 13.42 (hrs)
357.503 at 13.40 (hrs)
660.135
2-yr 24-hr SCS Method Design Storm
14.439 at 11.92 (hrs)
4.807 at 12.08 (hrs)
357.861 at 12.08 (hrs)
751.748
Hydrograph 2
Routing Summary
of
Peaks: 10-yr
24-hr
SCS Method
Design Storm
inflow
(cfs)
26.434
at
11.92
(hrs)
discharge
(cfs)
20.861
at
12.00
(hrs)
water level
(ft)
358.773
at
12.00
(hrs)
storage
(cy)
1017.214
Hydrograph 3
Routing Summary
of
Peaks: 100-yr
24-hr SCS
Method Design Storm
inflow
(cfs)
50.597
at
11.92
(hrs)
discharge
(cfs)
49.660
at
11.92
(hrs)
water level
(ft)
359.003
at
11.92
(hrs)
storage
(cy)
1091.569
Wed Apr 22 10:33:42 EDT 2020
Page 4
AMENDED Riprap Lined Outlet Protection Calculations
(DA 6)
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Plate 3.18-3
TIT -I.CA
AMENDED DEQ Virginia Runoff Reduction
Method Water Quality Calculations
Compliance is met through the two best management practices of a level II wet
pond and the purchasing of nutrient credits, consistent with the originally
approved VSMP plan. Please note however, the following water quality
calculations were updated with this amendment to reflect an increased limits of
disturbance. The result is a minor increase in the phosphorous loading required
to be removed. The original VSMP approved plan required a nutrient credit
purchase of 6.24 Ibs/yr. This amendment now requires a total nutrient credit
purchase of 6.68 Ibs/yr. This is an additional 0.44 Ibs/yr. of phosphorous.
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Runoff
Volume and Curve Number Calculations
Enter design storm rainfall depths (in):
1-year storm 2-year storm 10-yearstorm
3.02 3.65 5.52
Use NOAA Atlas 14 (hap://hdsc.nw noaa.go lhdsc/pfds/)
*Notes (see below):
[1] The curve numbers and runoff volumes computed in this spreadsheet for each drainage area are limited in their applicability for determining and demonstrating compliance with water quantity
requirements. See VRRM User's Guide and Documentation for additional information.
[2] Runoff Volume (RV) for pre- and post -development drainage areas must be in volumetric units (e.g., acre-feet or cubic feet) when using the Energy Balance Equation. Runoff measured in watershed -
inches and shown in the spreadsheet as RV(watershed-inch) can only be used in the Energy Balance Equation when the pre- and post -development drainage areas are equal. Otherwise RV(watershed-inch)
must be multiplied by the drainage area.
[3] Adjusted CNs are based on runoff reduction volumes as calculated in D.A. tabs. An alternative CN adjustment calculation for Vegetated Roofs is included in BMP specification No. 5.
Drainage Area Curve Numbers and Runoff Depths*
Curve numbers (CN, CNadj) and runoff depths (RV oe�ela ed) are computed with and without reduction practices.
Drainage Area
ASoils
BSoils
CSoils
DSoils
Total Area (acres): 6.02
Forest/Open Space-- undisturbed, protected forest/open
space or reforested land
Area (acres)
CN
0.00
30
0.00
55
0.00
70
0.00
77
Runoff Reduction
Volume ftt : 0
Managed Turf --disturbed, graded for yards or other turf
to be mowed/managed
Area (acres)
CN
0.00
39
2.22
61
0.00
74
0.00
80
Impervious Cover
Area (acres)
CN
0.00
98
3.80
98
0.00
98
0.00
98
_
CN(D.A. A)
84
1-year storm
2-year storm'',
10-year storm
RVa-Iii,ped (watershed -inch) with no Runoff Reduction*
1.53
2.07
3.75
RVpe„e101d (watershed -inch) with Runoff Reduction*
1.53
2.07
3.75
Adjusted CN*
--
84
ga
*See Notes above
Drainage Area B
A Soils
B Soils
C Soils
D Soils
Total Area (acres): 0.00
Forest/Open Space -- undisturbed, protected forest/open
space or reforested land
Area (acres)
CN
0.00
30
0.00
55
0.00
70
0.00
77
Runoff Reduction
Volume fts : 0
Managed Turf --disturbed, graded for yards or other turf
to be mowed/managed
Area (acres)
CN
0.00
39
0.00
61
0.00
74
0.00
80
Impervious Cover
Area (acres)
CN
0.00
98
0.00
98
0.00
98
0.00
98
CN(D.A. a)
0
1-yearstorm
2-yearstorm
10-yearstorm
RV�loped (watershed -inch) with no Runoff Reduction*
0.00
0.00
0.00
RVpe„elapld (watershed -inch) with Runoff Reduction.1
0.00
0.00
0.00
Adjusted CN*
1 e
0
0
*See Notes above
Drainage Area C
A Soils
B Soils
C SoilsrDils
Total Area (acres): 0.00
Forest/Open Space -- undisturbed, protected forest/open
space or reforested land
Area (acres)
CN
0.00
30
0.00
55
0.00
70
Runoff Reduction
Volume ft: 0
Managed Turf -disturbed, graded for yards or other turf
be mowed/managed
Area(acres)
CN
0.00
39
0.00
61
0.00to
74Impervious
Cover
Area (acres)
0.00
98
0.00
98
0.00CN
98
0
1-yearstorm
2-year storm
10-yearstorm
RVpeeloped (watershed -inch) with no Runoff Reduction*
0.00
0.00
0.60
RVD_eloped (watershed -inch) with Runoff Reduction*
0.00
0.00
0.00
Adjusted CN*
0
0
0
*See Notes above
Drainage Area D
A Soils
B Soils
C Soils
D Soils
Total Area (acres): 0,00
Forest/Open Space -- undisturbed, protected forest/open
space or reforested land
Area (acres)
CN
0.00
30
0.00
55
0.00
70
0.00
77
Runoff Reduction
Volume fta : 0
Managed Turf -disturbed, graded for yards or other turf
to be mowed/managed
Area (acres)
CN
0.00
39
0.00
61
0.00
74
0.00
80
Impervious Cover
Area (acres)
CN
0.00
98
0.00
98
0.00
98
0.00
98
CNID.A. DI
0
1-year storm
2-year storm
10-yearstorm
RV�„eloped (Watershed -inch) with no Runoff Reduction*
0.00
0.00
0.00
RVDeveloped (watershed -inch) with Runoff Reduction*
0.00
0.00
0.00
Adjusted CN*
r o
0
0
*See Notes above
Drainage Area E
A Soils
B Soils
C Soils
D Soils
Total Area (acres): 0,00
Forest/Open Space -- undisturbed, protected forest/open
space or reforested land
Area (acres)
CN
0.00
30
0.00
55
0.00
70
0.00
77
Runoff Reduction
Volume (ft'): 0
Managed Turf -disturbed, graded for yards or other turf
to be mowed/managed
Area (acres)
CN
0.00
39
0.00
61
0.00
74
0.00
80
Impervious Cover
Area (acres)
CN
0.00
98
0.00
98
0.00
98
0.00
98
CNID.A. EI
0
1-year storm
2-yearstorm
10-yearstorm
RVD-eloped (watershed -inch) with no Runoff Reduction*
0.00
0.00
0.60
RVDmloped (Watershed -inch) with Runoff Reduction*
0.00
0.00
0.00
'Adjusted CN*
0
0
0
*See Notes above
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