DaVita Spencer - Copy of Supplement_Wet Basin_Rev9_Locked

Permit No.______________________
(to be provided by DWQ)
I. PROJECT INFORMATION
Project name
Contact person
Phone number
Date
Drainage area number
II. DESIGN INFORMATION
Site Characteristics
Drainage area 97,139 ft2
Impervious area, post-development 46,609 ft2
% impervious 47.98 %
Design rainfall depth 1.0 in
Storage Volume: Non-SA Waters
Minimum volume required 5,018 ft3
OK, volume provided is equal to or in excess of volume required.
Storage Volume: SA Waters
1.5" runoff volume ft3
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required ft3
Peak Flow Calculations
Is the pre/post control of the 1yr 24hr storm peak flow required? y (Y or N)
1-yr, 24-hr rainfall depth 2.7 in
Rational C, pre-development 0.40 (unitless)
Rational C, post-development 0.70 (unitless)
Rainfall intensity: 1-yr, 24-hr storm 4.62 in/hr OK
Pre-development 1-yr, 24-hr peak flow 0.59 ft3/sec
Post-development 1-yr, 24-hr peak flow 4.45 ft3/sec
Pre/Post 1-yr, 24-hr peak flow control 3.87 ft3/sec
Elevations
Temporary pool elevation 737.75 fmsl
Permanent pool elevation 736.50 fmsl
SHWT elevation (approx. at the perm. pool elevation) 731.00 fmsl
Top of 10ft vegetated shelf elevation 740.00 fmsl
Bottom of 10ft vegetated shelf elevation 736.00 fmsl
Sediment cleanout, top elevation (bottom of pond) 732.00 fmsl
Sediment cleanout, bottom elevation 731.00 fmsl
Sediment storage provided 1.00 ft
Is there additional volume stored above the state-required temp. pool? n (Y or N)
Elevation of the top of the additional volume fmsl
401 CERTIFICATION APPLICATION FORM
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
1
Volume provided
ft3
ft3
336-218-8282
27-Jul-17
This form must be filled out, printed and submitted.
WET DETENTION BASIN SUPPLEMENT
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
Matt Johnson, PE
DaVita Spencer
Volume provided 8,524
Form SW401-Wet Detention Basin-Rev.9-4/18/12 Parts I. & II. Design Summary, Page 1 of 2
Permit No.______________________
(to be provided by DWQ)
II. DESIGN INFORMATION
Surface Areas
Area, temporary pool 7,978 ft2
Area REQUIRED, permanent pool 3,167 ft2
SA/DA ratio 3.26 (unitless)
Area PROVIDED, permanent pool, Aperm_pool 5,660 ft2 OK
Area, bottom of 10ft vegetated shelf, Abot_shelf 4,148 ft2
Area, sediment cleanout, top elevation (bottom of pond), Abot_pond 1,366 ft2
Volumes
Volume, temporary pool 8,524 ft3 OK
Volume, permanent pool, Vperm_pool 13,179 ft3
Volume, forebay (sum of forebays if more than one forebay) 2,636 ft3
Forebay % of permanent pool volume 20.0% % OK
SA/DA Table Data
Design TSS removal 90 %
Coastal SA/DA Table Used?n (Y or N)
Mountain/Piedmont SA/DA Table Used? y (Y or N)
SA/DA ratio 3.26 (unitless)
Average depth (used in SA/DA table):
Calculation option 1 used? (See Figure 10-2b) n (Y or N)
Volume, permanent pool, Vperm_pool 13,179 ft3
Area provided, permanent pool, Aperm_pool 5,660 ft2
Average depth calculated ft Need 3 ft min.
Average depth used in SA/DA, dav, (Round to nearest 0.5ft)ft
Calculation option 2 used? (See Figure 10-2b) y (Y or N)
Area provided, permanent pool, Aperm_pool 5,660 ft2
Area, bottom of 10ft vegetated shelf, Abot_shelf 4,148 ft2
Area, sediment cleanout, top elevation (bottom of pond), Abot_pond 1,366 ft2
"Depth" (distance b/w bottom of 10ft shelf and top of sediment) 4.00 ft
Average depth calculated 3.42 ft OK
Average depth used in SA/DA, dav, (Round to down to nearest 0.5ft)3.4 ft OK
Drawdown Calculations
Drawdown through orifice?y (Y or N)
Diameter of orifice (if circular)0.75 in
Area of orifice (if-non-circular)in2
Coefficient of discharge (CD)0.60 (unitless)
Driving head (Ho)2.00 ft
Drawdown through weir?n (Y or N)
Weir type (unitless)
Coefficient of discharge (Cw)(unitless)
Length of weir (L)ft
Driving head (H)ft
Pre-development 1-yr, 24-hr peak flow 0.59 ft3/sec
Post-development 1-yr, 24-hr peak flow 4.45 ft3/sec
Storage volume discharge rate (through discharge orifice or weir) 0.02 ft3/sec
OK, draws down in 2-5 days.
Additional Information
Vegetated side slopes 3 :1 OK
Vegetated shelf slope 10 :1 OK
Vegetated shelf width 10.0 ft OK
Length of flowpath to width ratio 3 :1 OK
Length to width ratio 2.0 :1 OK
Trash rack for overflow & orifice?y (Y or N) OK
Freeboard provided 1.1 ft OK
Vegetated filter provided?n (Y or N) OK
Recorded drainage easement provided? y (Y or N) OK
Capures all runoff at ultimate build-out? y (Y or N) OK
Drain mechanism for maintenance or emergencies is:Drain Pipe w/ Vlave
Storage volume drawdown time 3.83 days
Form SW401-Wet Detention Basin-Rev.9-4/18/12 Parts I. & II. Design Summary, Page 2 of 2