20170986 Ver 1_SW Plan_20170808

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_ Highway Stormwater Program
STORMWATER MANAGEMENT PLAN "'':f-..
(Version 2.07; Released October 2016) FOR NCDOT PROJECTS
WBS Element: 178P.9.R.62 TIP No.: SF 790236 County ies : Rowan Page 1 of 2
General Project Information
WBS Element: 17BP.9.R.62 TIP Number: SF 790236 Pro�ect T pe: Brid e to Culvert Date:
NCDOT Contact: Chris Lewis, PE Contractor / Designer: Liz DiNatale, PE
Address: 1590 Mail Service Center Address: SEPI En ineering & Construction
Raleigh, NC 27699-1590 1025 Wade Avenue
Ralei h NC 27605
Phone: Phone: [phone]
Email: Email: LDiNatale@sepien ineerin .com
CitylTown: Near Lexington, NC County(ies): Rowan
River Basin s: Yadkin-Pee Dee CAMA Count ? No
Wetlands within Project Limits? Yes
Pro'ect Description
Project Length (lin. miles or feet): 260 ft. Surrounding Land Use: Agricultural / Rural ! Light Residential
Pro osed Pro"ect Existin Site
Project Built-Upon Area (ac.) 0.1 ac. 0.1 ac.
Typical Cross Section Description: 2@ 12' Travel Lane with 4' Paved Shoulders - Normal Crown 2@ 9' Travel Lane with grassed shoulders - Normal Crown
Annual Avg Daily Traffic (veh/hr/day): Design/Future: 1020 Year: 2025 Existing: 500 Year: 2010
General Project Narrative: The NCDOT will be replacing the existing brdige on SR 1221 (Bostian Rd) over Town Branch in Rowan County. The existing bridge is a single span at 25.5' on timber brdige
(Description of Minimization of Water seats and 0.8' vertical abutments. The surveyed actual opening of 23.9' was taken inside the bridge seats and 0.8' vertical abutments. The surveyed actual opening of 23.9' was
Quality Impacts) taken inside the bridge seats. The proposed replacement is a double 11'x9' Reinforced Concrete Box Culvert at approximately 48' in length. The proposed double 11'x9' RCBC
will be buried 1' with 1' sills in the left culverts (facing downstream) to act as the low flow barrel and a 2' sill in the farthest right barrel to serve as a floodplain bench culvert.
Waterbod Information
Surface Water Body 1: Town Branch NCDWR Stream Index No.: 12-84-1-2
NCDWR Surface Water Classification for Water Body Primary Classification: Water Supply IV (WS-IV)
Supplemental Classification: None
Other Stream Classification: None
Impairments: None
Aquatic T&E Species? No Comments:
NRTR Stream ID: Buffer Rules in Effect: N/A
Project Includes Bridge Spanning Water Body? N/A Deck Drains Discharge Over Buffer? N/A Dissipator Pads Provided in Buffer? N/A
Deck Drains Dischar e Over Water Bod ? N/A (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)

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Highway Stormwater Program � "
STORMWATER MANAGEMENT PLAN `"�'.-.:. .:���'"
(Version 2.07; Released October 2016) FOR NCDOT PROJECTS
WBS Element: 17BP.9.R.62 TIP No.: SF 790236 County(ies): Rowan Page 2 of 2
Bridge to Culvert Avoidance and Minimization
Proposed Structure Summary
Sheet No. & Station Sheet No.: 4 Station: 13+45.5 Number of Barrels: 2
Drainage Area (ac or sq mi): 1.15 SQ MI. Barrel Width/Diameter (ft): 11
Surface Water Body: (1)Town Branch Barrel Height (ft): 9
Culvert T e: RCBC Culvert Length (ft) 48
Avoidance and Minimization Efforts: Minimal Change to existing footprint and profile / 2:1 fill slopes used / Minimal channel improvements required to tie back to existing
(Bridge to Culvert)
Stream Slope Fish and/or Aquatic Life Passage
Existing Average Stream Slope %): 1.00 % Existing Low Flow Channel Dimensions 7-8 FT Base - Low Flow Channel (+/-) ; 1.5:1
Proposed Culvert Slope (%): 1.00 % in the Stream: Side Slopes ; 7 FT Depth
Culvert Burial
Proposed Culvert Burial Depth (ft): 1 FT
Existing Streambed Material: SAND, SMALL TO LARGE ROCKS, BED ROCK Proposed Low Flow Dimensions 11 FT Low Flow Barrel Width Total
Through the Culvert:
Proposed Sills/Batfles: 1 FT Sill (At Inlet, Middle, and Outlet) / 2 FT Sill (RT
Barrel Facing Downstream) xistmg Low ow e oaties in t e
Stream (ft/s):
5.60 (10-yr)
ropose ow ow e oci ies roug
the Culvert ft/s): 8.82 (10-yr)
Alternating Low Flow Sills/Baffles: Sills provided as described to the left - no
baffles proposed (no meandering low flow
channel to retain)
Culvert/Stream Alignment
Stream Patterns Upstream and Relatively straight alignment in vicinity of culvert / Banks stable/ Pattern stable
Downstream of the Culvert that Could
Affect Fish Passa e and Bank Stabilit :
Bed Forms Impacted by Culvert (riffles, Culvert sits between 2 bends at a riffle.
pools, glides, etc.):
Low Flow Floodplain Bench Required? Y2S Right barrel will function as floodplain barrel and is designed to be inundated in a near bank full scenario. This helps maintain the effectiveness of the low flow channel.
(provide justification) W hich will maintain the sediment transport of the stream and the health of the organisms within the ecosystem.
Bends at Inlet/Outlet? No Stream is straight at outlet for approximately 70ft. before turning.
describe culvert ali nment with stream
Stream Realignment Necessary? (provide Yes Minor channel improvements required - see Culvert Survey Report in Plan View
justification)
Bank Stabilization: Minor Channel improvements required - see Culvert Survey Report in Plan View
Outlet Velocities
Natural Stream Channel 2-yr Velocity (ft/s : 3.81 Natural Stream Channel 10-yr Velocity (ft/s): 6.19
Proposed Culvert 2-yr Outlet Velocity (ft/s): 5.87 Proposed Culvert 10-yr Outlet Velocity (ft/s): 7.79
Roadwa Geometric Considerations
Evaluate/Describe Roadway Geometric Constraints:
Proposed roadway geometry generally matches existing - Bridge replacement is primary reason for project.