SW8120806_COMPLIANCE_20120815

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
❑ HISTORICAL FILE
COMPLIANCE EVALUATION INSPECTION
DOC DATE
YYYYMMDD

WET DETENTION POND ANALYSIS - ALL RULES
FILE NAME:
S:LWQSISTORMWATERIEXCELSPREADSHEETSIPONDI120806
PROJECT* SWB
120806
REVIEWER:
Initial Run Date
PROJECT NAME:
dRMO Storage Lot
Last modified
Receiving Stream:
Cogdels Creek
Class:
Drainage Basin;
lWhite Oak
Within 1/2 mile SA?
Index No.
15-Aug-12
sC;NSW
0
119-23 1
Site Area 2.40 acres
0Drainage Area 103427.00 square feet DA Area 2.37 acres
Rules- "2008" or "Ph2" 2008
IMPERVIOUS AREAS - BUA Runoff C
Buildings square feet 1
Parking 47007.00 square feet 0.98
SW square feet 0.95
Future square feet 0,95
Offsite square feet 0,95
Other square feet 0.95
[BUA at dill. DSO square feet 0.95
TOTAL 47007.00 square feet
SURFACE AREA CALCULATION (with added DA and BUA at different design storm)
Overall % Impervious 45.45% SAIDA Ratio 4.54%
Average Design Depth 3.5 feet Req. SA 4701 sf
TSS, 85 or 90: 90 % Prov. SA 7303 sf
TEMPORARY POOL AND FOREBAY VOLUME CALCULATIONS
New BUA
Drainage Area® 103427.00
BUA 47007.00
Post development Rv= 0.459
Old BUA Design Storm
Old BUA Design Volume
1.5" New BUA Design Storm Volume 5935
1 yr. 24 hour precipitation depth (inches) 3.70 fn
PredevelopmentRvvalue 0.05 U.
1 yr. 24 hr. Pre -development volume 1594 u
i yr. 24 hr. Post -development volume 14639 a
2008 Design Volume 5935 cubic feet
Phase 2 Design Volume 5935 cubic feet
Required Volume 5935. cf
Top of Sediment 22.00 msl .........
Bottom of Shelf 27.00 msl..........
Permanent Pool 27.50 msl.........
Top of Shelf
28.00
msl..........
Temporary Pool
28.75
msl.........
Volume met at elev
28.50
msl
Vol. Prov. at TP
11526.75
1 cf
Calculated Averatae Depth, feet = 13.72
Old BUA
sf
0.00 sf
#DIV/01 unities
inches
0
m NOAA chart
e 0.05 if n0 existing BUA
bic feet
bic feet
Area, sf
1719.00
5491.00
7303.00
i
Inc. volume
Acc, volume
0.00
0.00
18025.00
18025.00
3198.50
21223.50
4137,75
25361.25
7389.00
32750.25
Perm. Pool Volume=
21224
Req. Forebay Volume=
4245
Provided Volume=
4302.00
Percent=
20.3%
Max Pump HP
NIA
ORIFICE CALCULATION
Average Head
Flow Q2, cfs
Flow Q5, cfs
No. of Orifices
Diameter, inches
Drawdown =
1 yr 24 hr intensity, in/hr
Runoff coefficient
I yr 24 hr peak Q
Orifice flaw<1y24hr ?
feet Q2 Area = 1.63
cfs Q5 Area = 0.65
cfs Orifice Area = 1.23
Avg. Flow Q= 0.026
or weir H x W in x
days `# of end contractions, N =
NOAA chart @t discharge coefficient, C =
unitless Effective weir length, L
cfs
sq. inches
sq. inches
sq. inches
cfs
0.40
0.034
0,014
1
1.25
2.6
0.15
3.32
0.58
10,00
0.21
YES -OK