SW8000918_COMPLIANCE_20001207

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SWIZ911�5
DOC TYPE
El CURRENT PERMIT
❑ APPROVED PLANS
❑ HISTORICAL FILE
ZP COMPLIANCE EVALUATION INSPECTION
DOC DATE
2zop /�e2 Z
YYWMMDD

i
DETENTION POND ANALYSIS
FILE NAME: S:IWQSIPOND1000918.WK1
PROJECT #: SW8 000918
PROJECT NAME: Hampstead Center
REVIEWER: arl
DATE: 07-Dec-2000
Receiving Stream: Mill Creek Class: SA Chlorides: 12 mg/I
Drainage Basin: Cape Fear Index No. 18-87-14
Site Area 27.70 acres
Drainage Area [„209210 00Isquare feet needs to be verified
Area in Acres 27.76 acres
IMPERVIOUS AREA
Lots
Street
Common Area
TOTAL
% IMPERVIOUS 59.75%
SURFACE AREA CALCULATION
642206.00 square feet
80241.00 square feet
0.00 square feet
square feet
square feet
square feet
�„ 72244700'
Des. Depth
Rational C-list beside
each item below in Ell to E20
0.98
0.98
Cc=
7.5 TSS:
0.67
Rational ? {
1.00 Ilf Rational is used put a
SA/DA
1.89%
"1" in box E26. If not, leave it blank.
Req. SA
22852 square feet
Prov. SA I
27787'1square feet
[From plan Contours]
VOLUME CALCULATION
Perm. Pool Volume= 98094
Req. Forebay Volume= 19618.8
Bottom
32.50 MSL
Provided Volume= 19619
Perm. Pool
40'00#MSL
Percent= [ 2000'
Design Pool
42.20 MSL
Desin SA
g
36 233 square feet
Des. Storm 1<OQ. inches
Req. Volume
671>13: cubic feet
Rv= 0.59
Prov. Volume
70422.cubic feet
SA @ _
Elevation=
ORIFICE CALCULATION
Avg. Head = 1.04 ft
Flow Q2, cfs 0.388 Area, in' 11.40
Flow Q5, cfs 0.155 , Area, in' 4.56
No. of Orifices 1' Diameter, in 3 00. Area = 7.069 in2
Q, cfs - 0.241 Drawdown = 3 2?jdays
COMMENTS
Surface Area , Volume and Orifice are within Design Guidelines.