SW1220301_Supplement-EZ Form_20220608

DRAINAGE AREAS
1
Is this a high density project?
Yes
2
If so, number of drainage areas/SCMs
1
3
Does this project have low density areas?
No
4
If so, number of low density drainage areas
0
5
Is all/part of this project subject to previous rule
versions?
No
FORMS LOADED
DRAINAGE AREA INFORMATION
Entire Site
1
4
Type of SCM
Bioretention
Bioretention
5
Total drainage area (sq ft
80586
74052
6
Onsite drainage area (sq ft)
80586
74052
7
Offsite drainage area (sq ft
0
0
8
Total BUA in project (sq ft)
59548 sf
59548 sf
9permitting)
New BUA on subdivided lots (subject to
s ft
10
New BUA not on subdivided lots (subject to
permitting) (sf)
59548 sf
59548 sf
11
Offsite BUA (sq ft
12
Breakdown of new BUA not on subdivided lots:
Parking (sq ft
59548 sf
59548 sf
Sidewalk (sq ft)
Roof (sq ft
Roadway (sq ft)
Future (sq ft
Other, please specify in the comment box
below (sq ft)
13
New infiltrating permeable pavement on
subdivided lots (sq ft
14
New infiltrating permeable pavement not on
subdivided lots (sq ft)
15
Existing BUA that will remain (not subject to
ermitting) (sq ft
16
Existing BUA that is already permitted (sq ft)
17
Existing BUA that will be removed (sq ft
18
Percent BUA
74%
80%
19
Design storm inches
1.0 in
20
Design volume of SCM (cu ft)
5812 cf
21
Calculation method for design volume
Simple Method
ADDITIONAL INFORMATION
22
Please use this space to provide any additional information about the
drainage area(s):
This project is within Asheville Regional Airport property, which has a
property area of 900ac. For the purposes of our calculations, the limits of
our construction, 1.85 acres, was used when determining built upon area
values.

BIORETENTION CELL
area n
2 1Minimum required treatment volume
GENERAL MDC FROM 02H .1050
3
Is the SCM sized to treat the SW from all surfaces at build -out?
Yes
4
Is the SCM located away from contaminated soils?
Yes
5
What are the side slopes of the SCM (H:V)?
3:1
6
Does the SCM have retaining walls, gabion walls or other
engineered side slopes?
No
7
Are the inlets, outlets, and receiving stream protected from erosion
(10-year storm)?
Yes
8
Is there an overflow or bypass for inflow volume in excess of the
design volume?
Yes
g
lWhat is the method for dewatering the SCM for maintenance?
Drawdown Orifice
10
If applicable, will the SCM be cleaned out after construction?
Yes
11
Does the maintenance access comply with General MDC (8)?
Yes
12
Does the drainage easement comply with General MDC (9)?
Yes
13
If the SCM is on a single family lot, does (will?) the plat comply with
General MDC (10)?
N/A
14
Is there an O&M Agreement that complies with General MDC (11)?
Yes
15
Is there an O&M Plan that complies with General MDC (12)?
Yes
16
Does the SCM follow the device specific MDC?
Yes
17
Was the SCM designed by an NC licensed professional?
Yes
BIORETENTION
CELL MDC FROM 02H .1 552
18
SHWT elevation (fmsl)
<2160.4
19
Bottom of the bioretention cell (fmsl)
2162.50
20
Ponding depth of the design storm (inches)
11 in
21
Surface area of the bioretention cell (square feet)
4861 sf
22
Design volume of SCM cu ft
5812 cf
23
Is the bioretention cell used for peak attenuation?
Yes
24
Depth of peak attenuation over planting surface (in)
18 in
25
Height of peak attenuation outlet above the planting surface (in)
12 in
26
Infiltration rate of the in situ soil (inch/hour)
N/A
27
Diameter of the underdrain pipes (if applicable)
4 in
28
Does the design include Internal Water Storage (IWS)?
Yes
29
if so, elevation of the top of the IWS (fmsl)
2165
30
Elevation of the planting surface (fmsl)
2166.5
31
What type of vegetation will be planted? (grass, trees/shrubs,
other)?
Grass
32
Media depth (inches)
36 in
33
Percentage of medium to coarse washed sand by volume
75-85%
34
Percentage of fines (silt and clay) by volume
8-15%
35
Percentage of organic matter by volume
5-10%
36
Type of organic material
Pine Bark Fines
37
Phosphorus Index (P-Index) of media (unitless)
<30
38
Will compaction be avoided during construction?
Yes
39
Will cell be maintained to a one inch/hour standard?
Yes
40
Depth of mulch, if applicable (inches)
Sod
41
Type of mulch, if applicable
Sod
42
IHow many clean out pipes are being installed?
1
43
IType of pretreatment that wi11 be use
ore ay
ADDITIONAL INFORMATION
44 Please use this space to provide any additional information about
the bioretention cell(s):
(9) The method of dewatering the bioretention area is the outlet control
structure.
Bioretention 2 4:05 PM 6/8/2022