20180331 Ver 1_17BP 5 R 71 SWMP_20180308

Highw�y North Carolina Department of Transportation ��'
Stormwaier i,�+ `I
,,.,,,.�,,,� Highway Stormwater Program s.J�_�
STORMWATER MANAGEMENT PLAN ---
(Version 2.07; Released October 2016) FOR NCDOT PROJECTS
WBS Element: 176P.5.R.71 TIP No.: SF-340025 County(ies): Franklin Page 1 of 1
General Project Information
WBS Element: 17BP.5.R.71 TIP Number: SF-340025 Pro'ect Type: Bridge Re lacement Date: 2/22/2018
NCDOT Contact: Matthew Lauffer, PE Contractor / Designer: David Fuh, PE
Address: NCDOT Hydraulics Unit Address: HDR Engineering, Inc.
1590 Mail Services Unit 555 Fayetteville Street, Suite 900
Ralei h, NC 27560 Ralei h, NC 27601
Phone: [phone] Phone: [phone]
Email: mslauffer ncdot. ov Email: david.fuh hdrinc.com
City/Town: Franklinton Count ies : Franklin
River Basin s: Tar-Pamlico CAMA Count ? No
Wetlands within Project Limits? Yes
Pro'ect Description
Project Length (lin. miles or feet): 0.161 miles Surrounding Land Use: Low Residential, Wooded
Proposed Pro'ect Existin Site
Pro'ect Built-Upon Area ac. 0.40 ac. 0.33 ac.
Typical Cross Section Description: Green Hill Road (SR 1203): 2 paved lanes (total 20' wide), 4' shoulder on each side (7' Green Hill Road (SR 1203): 2 paved lanes (total 17' wide)
with guardrail).
Annual Avg Daily Traffic (veh/hr/day): Desi n/Future: 1000 Year: 2025 Existin : 510 Year: 2012
General Project Narrative: The North Carolina Department of Transportation (NCDOT) has proposed to replace Franklin County Bridge #25 on Green Hill Road (SR 1203) over Middle Creek. The existing
(Description of Minimization of Water structure is a two span bridge (1 @35.5', 1@30.5') and is a timber floor on I-Beams supported by 1 concrete pier abutment and steel cap and H-piles interior and end bents. The
Quality Impacts) proposed structure is a two span (1 @35', 1@85'), 33" box beam with 4' deep caps. This structure has been designed to have as little environmental, wetland, and surface water
impacts as possible. Geotextile and rip-rap was utilized for bank stabilization in an attempt to reduce stream bank erosion along the west bank of the channel underneath the
existing bridge and the east bank of the channel underneath the proposed bridge. 2:1 roadway fill slope will be used in the wetland areas to minimize wetland impacts.
Permanent drainage easement (PDE) will be set to have as little wetland impacts as possible. To avoid direct discharge of bridge storm water into the receiving water, deck
drains are not required for the proposed bridge. Storm water impacts to the stream have been minimized by utilizing grated inlets and pipes to collect bridge storm water and use
rip rap outlet protection at 13+65 RT to dissipate energy to provide a diffuse flow (non-erosive sheet flow) to a wooded area. This diffuse flow will run for a distance of 70'+/-
before entering the buffer. At the same NE quadrant, there is an existing roadside ditch that will be retained and lined with toe protection along the fill slope. The ditch outfalls to
a 15" RCP driveway pipe that will be removed and replaced. The pipe outlets to Class B Rip Rap and the existing ditch outfalls at 12+15 RT with a non-erosive outlet velocity
into a wooded area where it sheet flows for approximately 200 ft before entering the buffer. There is an existing drainage divide at 17+50 RT that will be retained. In the NW
quadrant, a proposed roadway typical 3:1 ditch beginning at the drainage divide will outfall to an existing 18" RCP at station 18+75 RT. In the same quadrant, the proposed
roadway typical 3:1 ditch beginning at 17+50 RT will tie into the existing roadside ditch at 16+50 RT. The existing ditch then outfalls at 15+09 with a non-erosive outlet velocity.
Due to the nature of low impact bridge replacement, the increases in stormwater discharges (post vs pre condition) are insignificant and the existing ditches do not need to be
modified. Therefore, additional stormwater measures are not required.
Waterbod Information
Surface Water Body (1 : Middle Creek NCDWR Stream Index No.: 28-15
NCDWR Surface Water Classification for Water Body Primary Classification: Class C
Supplemental Classification: Nutrient Sensitive Waters NSW
Other Stream Classification: None
Impairments: None
A uatic T&E S ecies? No Comments:
NRTR Stream ID: Buffer Rules in Effect: Tar-Pamlico
Project Includes Brid e Spanning Water Bod ? Yes Deck Drains Discharge Over Buffer? No Dissipator Pads Provided in Buffer? No
Deck Drains Dischar e Over Water Body? No (If yes, provide justification in the General Project Narrative) (If yes, describe in the General Project Narrative; if no, justify in the
(If yes, provide justification in the General Project Narrative) General Project Narrative)