SW5240201_Stormwater Narrative_20240219

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5410 Trinity Road P 919.866.4951
T I M M O N S GROUP Suite 102 F 919.859.5663
YOUR VISION ACHIEVED THROUGH OURS. Raleigh, NC 27607 www.timmons.com
November 27, 2023
NC Dept of Enviro. Quality
Raleigh Regional Office
Attn: Jim Farkas
512 N. Salisbury Street
Office 640 E
Raleigh, NC 27604
Subject: CONSTRUCTION SEQUENCE/ NARRATIVE
Project Name: Wrenn Farms
County: Franklin
City: Youngsville
Dear Mr. Farkas,
The proposed 183 lot Townhome subdivision, Wrenn Farms, will be constructed as one project with
(1) one proposed Wet Pond SCM. The proposed SCM will also treat the future Wrenn Apartments site.
SCM #1 will be constructed, as part of the subdivision improvements, to reduce the pre-to post-
development peak flows conditions for the 10-, 25-year, 24-hour storm event of the proposed
development. Additionally, this project will propose an 85% Total Suspend Solids removal and will treat the
required Water Quality Volume per NCDEQ requirements.
A pre-development and post-development hydrologic analysis was completed for the site using the NRCS
(SCS) method. A hydraulic analysis was completed using Hydraflow modeling software to route these storm
events through the proposed detention and outlet structures.
The runoff from our project site discharges Richland Creek and is part of the Neuse River Basin — Phase II ETJ
Area. The Town of Youngsville is not named Nutrient Sensitive Water Town however the site is in a Tipped
County and requires post-construction stormwater permitting through NCDEQ to confirm Neuse Basin Rules, 15A
NCAC 02H .1017, compliance.
CIVIL ENGINEERING I ENVIRONMENTAL I SURVEYING I GIS I LANDSCAPE ARCHITECTURE I CONSTRUCTION SERVICES

CIVIL ENGINEERING I ENVIRONMENTAL I SURVEYING I GIS I LANDSCAPE ARCHITECTURE I CONSTRUCTION SERVICES