SW5210305_Stormwater Narrative_20210514

Town of Siler City
Water Treatment Plant Improvements Phase 2
Stormwater Treatment Narrative
The proposed project includes improvements to the Town of Siler City's water treatment plant
Reconfiguration of parking at the site and the addition of a new pretreatment unit are the
primary additions to the facility with additional impervious surface.
Stream and wetlands delineations were completed for the site and only identified one stream
within 200 feet of the proposed improvements as shown on the project plans.
The facility and improvements are located on parcels with PIN 8763 00 31 7634 (57.85 acres)
and 8763 00 32 2824 (40 Acres) for a total of 97.85 acres. The properties are owned for the
purpose of the watershed and water treatment facilities and other development is not
anticipated.
The proposed project is sited at the top of a basin and all stormwater flow is proposed to sheet
flow away from the site and into wooded areas. There are no concentrated flows from the
proposed low -density site. Being at the top of the basin, the area drains to two separate stream
indexes as shown in Section IV.10 of the Stormwater Management Permit Application Form.
Stormwater from the northern portion of the project site drains to the Rocky River upstream of
the dam into the Class C 17-43-(8) stream index and stormwater that falls into the southern part
of the project area flows to the Rocky River downstream of the dam into the Class WS-III; CA
17-43-(5.5) stream index.
March 2021 SWU-101 Stormwater Narrative