SW5100602_Stormwater Narrative_20181016

Designing the Future…Today!
J. Michael Stocks, PE 252.459.8196 (voice)
801 East Washington St.252.459.8197 (fax)
PO Box 1108 252.903.6891 (mobile)
Nashville, NC 27856 [e-mail]
Monday October 1st, 2018
Sue Homewood
NCDEQ - Stormwater Engineering
585 Waughtown Street
Winston Salem, NC 27107
RE: ABB Power T & D Co. Inc, Pinetops NC (Permit No. SW5100602)
Dear Mrs. Homewood:
The owners of the ABB Power T & D Co. in Pinetops, NC would like to expand their existing
facility with a new 32,000 SF building. The existing main building and parking consisted of 265,287
SF of impervious area and was completed prior to 1994. In 2010 there was an expansion of the
facility and parking area that added 73,406 SF of impervious area. At that time a State Stormwater
Permit was approved (Permit No. SW5100602) and a wet detention pond was built and designed to
treat 250,795 SF of existing impervious area. However, only 73,406 SF of impervious from the
building and parking addition was required to be treated. Therefore, an additional 177,389 SF of
impervious was treated by the pond that had not yet been built or planned.
The current proposed building shown in the attached plans is 32,000 SF and the proposed
drive and parking will consist of 45,248 SF of impervious area. There is also an additional future
expansion planned that will consist of 41,688 SF of impervious area. Currently the active
stormwater permit lists the following impervious surfaces:
We would like to adjust these totals to match the proposed criteria to include the proposed
and future development plans. Since the wet detention pond was designed and built to treat
177,389 SF of future impervious these changes will not increase the needed capacity of the wet
pond.
The proposed building and loading dock are designed to bypass the existing pond. The
impervious area is being treated through the pond by treating pre-1994 impervious area.
Copies of the proposed plan are attached. The overall site plan can be found on sheet CE-02
while the details of the changes in impervious area can be found on the cover sheet.
Sincerely,
Ethan Averette
Stocks Engineering
Existing Permit Criteria Proposed Criteria
Total Impervious Surfaces, ft2 250,795 250,795
Buildings, ft2 25,600 89,600
Roads/Parking, ft2 32,981 68,541
Other, ft2 192,214 92,654
Offsite, ft2 0 0