SW5190703_Form_(Supp.EZ)_20200408

DRAINAGE AREAS
1 Is this a high density project? Yes
2 If so, number of drainage areas/SCMs 1
3
Is all/part of this project subject to previous rule
versions? No
FORMS LOADED
Entire Site 1
4 Type of SCM Sand Filter
5 Total BUA in project (sq ft) 48152 sf 22819 sf
6
New BUA on subdivided lots (subject to
permitting) (sq ft)
7
New BUA outside of subdivided lots (subject to
permitting) (sf) 4810 sf
8 Offsite - total area (sq ft) 6789 sf
9 Offsite BUA (sq ft) 3491 sf
10 Breakdown of new BUA outside subdivided lots:
- Parking (sq ft)
- Sidewalk (sq ft)
- Roof (sq ft)
- Roadway (sq ft)
- Future (sq ft)

- Other, please specify in the comment box
below (sq ft) 4810 sf
11
New infiltrating permeable pavement on
subdivided lots (sq ft)
12
New infiltrating permeable pavement outside of
subdivided lots (sq ft)
13
Exisitng BUA that will remain (not subject to
permitting) (sq ft) 43342 sf 22819 sf
14 Existing BUA that is already permitted (sq ft)
15 Existing BUA that will be removed (sq ft) 1374 sf
16 Percent BUA 42% 41%
17 Design storm (inches) 1 in 1 in
18 Design volume of SCM (cu ft) 1500 cf 1500 cf
19 Calculation method for design volume Simple Method
20
DRAINAGE AREA INFORMATION
ADDITIONAL INFORMATION
Other in the Enitre Site Column refers to the net increase in impervious on
site. Drainage area 1 corresponds to the area being routed to the sand filter.
Please use this space to provide any additional information about the
drainage area(s):
SAND FILTER
1 Drainage area number 1
2 Design volume of SCM (cu ft) 1500 cf
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)? :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
9 What is the method for dewatering the SCM for maintenance? Pump (preferred)
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)? No
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
18 SHWT elevation (fmsl) 345.64
19 Type of sand filter (open or closed) Closed
20 If closed, will the filter will be pre-cast or pour-in-place? Pre Cast
21 If closed, top of grate elevation (fmsl)350.45, 348.43, 347.35
22 Is this sand filter designed to attenuate peak flows? Yes
23 Volume that can be retained in the sediment chamber (cubic feet)750 cf
24 Will there be a permanent pool in the sediment chamber? Yes
25 Bottom of the sediment chamber (fmsl)337.00
26 Area of the sediment chamber (square feet)750 sf
27 Physical depth of the sediment chamber (inches)72 in
28
Ponding depth in the sediment chamber, above any permanent pool
(inches) 12 in
29 Elevation of top of weir between chambers (fmsl) 339.5
30 Volume that can be retained in the sand chamber (cubic feet)750 cf
31 Bottom of the sand chamber (fmsl)337.00
32 Area of the sand chamber (square feet)750 sf
33 Physical depth of the sand chamber (inches)72 in
34
Ponding depth in the sand chamber, above any permanent pool
(inches) 12 in
35 Elevation of the bypass device (fmsl) 340.5
36 Type of bypass device 6" DIP
37 Mechanism for distributing flow over the sand surface Weir
38 Sand specification for sand chamber ASTM C-33
39 Depth above underdrain pipe (inches) 18 in
40
Will the media be maintained to drain at least two inches per hour at
the sand surface? Yes
41
Is at least one clean-out pipe provided at the low point of each
underdrain line? Yes
42 Will clean-out pipes be capped? Yes
43
Please use this space to provide any additional information about the
Sand Filter(s):
The Sand Filter is entirely closed. The top of grate elevations listed
are the top of access hatch to get into the sand filter for maintenace.
SAND FILTER MDC FROM 02H .1056
GENERAL MDC FROM 02H .1050
Sand Chamber
Sediment Chamber
ADDITIONAL INFORMATION
Sand Filter 1 8:50 AM 3/31/2020