SW8990421_COMPLIANCE_19991229

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT N0.
SW��v�O� I
DOC TYPE
❑CURRENT PERMIT
❑ APPROVED PLANS
❑ HISTORICAL FILE
COMPLIANCE EVALUATION INSPECTION
DOC DATE
YYYYMMDD

City of Wilmington
Park Avenue Right of Way Improvents Project
Wallace Avenue to 52nd Street
December 15, 1999
08240055.OW (40)
On -Site Imprevious Area Tabulation
On -Site Built Upon
Area (sf)
Bioretentention Area
----------------------------;
------------- i-------------
1 2 3
4
Street
7,084: 6,270: 9,8121
12,760
Bike Path
-------------"+------------'
3,213: 2,904, 3,982:
3,278
Side Walk
11-408: 1,364� 1,232� 1,914
Drives
308; 959; 713; 1,584
Totals
12,013: 11,497: 15,739:
19,536
ql
� f � I 1 1 I �- •II
E C E I V E
DEC 2 91999
FROJ # O42
Bioretention Impervious Areas.xis 1

Park Avenue Right of Way Roadway Improvements
08240055.OW (40) City of Wilmington
Bioretention #3 j0 f 1 0
Bioretention Sizing Calculation n
v
0% .
with out sand bed (7% sum of c x area) a, iL b p
0?"c 87 w
Total Basin Area Ta = 2.97 acres
Impervious Area C -47 +'J�rA''�stiit►>•
sf 4
(.07-C•Ta)•43560 = 4256.38 minimum bioretention surface area
surface area provided = 4860 sf
Bioretention Stage/Storage
data ._ ,
31.251 4860,001 (4860 - 6207) Qe✓
31.70 fi207.00 Volume 2 �(31.7 - 31.25) Volume = 2490.07
. <:'.�-1 �l�lsg
Storage Draw Down
Use 1/2 of the min. Infiltration rate provised
Infiltration Rate inch/hour Ir := 1.8 by Soil Tech Engineering for this site.
Bioretention Bottom Aria Ap = 4860
Q .- Ap• [r Q = 0.2
12,3600
Time := Volume lume Time = 0.14 days Note : less that 4 days
0,86400
Peak Runoff Reduction
P .= 4.5 2 year storm
1000
CN :- 75 S :- CN - t0
(P-02-S)'`
Runoff z P r b 8 S). Runoff = 2.05
Infiltration Volume to Runoff Volume
Ir
= 0.88 Enter in Figure 6-1 of the TR-55 Manual
Ruff as ratio of storage to runoff volume (VsNr)
The ratio of peak outflow discharge
1 to peak inflow discharge (Qo/Qi) 90 % reduction in the 2 year storm
bra.mcd

R
Park Avenue Right of Way Roadway Improvements
08240055.OW (40)
City of Wilmington
Bioretention #4
Bioretention Sizing Calculation
with out sand bed (7% sum of c x area)
Total Basin Area Ta = 2.21 acres
Impervious Area C .47
�r
i
sf
(.07 C'Ta)'43560 = 3167.2 minimum bioretention surface area n d
surface area provided = 3100 sf
Bioretention StagelStorage
data =
30.351 3100.00 (3100 _ 3972)
30.80 3972.00 Volume = 2 (30.8-30.35) Volume= 1591?
Storage. Draw Down
Use 112 of the min. Infiltration rate provised
Infiltration Rate inch/hour Ir 1.8 by Soil Tech Engineering for this site.
Bioretention Bottom Area Ap 3100
Ir
Q Ap' 1273-60-0 Q = 0.13
Time,- Q_.- Volume 86400 Time = 0.14 days Note :less that 4 days
Peak Runoff Reduction
P := 4.5 2 year storm
1000
CN := 75 S .- CN - 10
Runoff:= Runoff= 2.05
P + 0.8-5
Infiltration Volume to Runoff Volume
Ir
Runoff = 0.88 Enter in Figure 6-1 of the TR-55 Manual
as ratio of storage to runoff volume (VsNr)
1 The ratio of peak outflow discharge
to peak inflow discharge (Qo/Qi) 90 % reduction in the 2 year storm
bra.mcd