20201784 Ver 1_Bridge #99 Diffuse Flow Plan_20201221

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"d — 'STORMWATER MANAGEMENT PLAN
(Version t08, Released APril 3018) « '-} „ FOR+ICOOT PROJECTS
WBS Element: 17BP.7.R.111 TIP No.: SF-670099 County(ies): Orange Page 1 of 1
General Project Information' , _
WBS Element: 17BP.7.R.111 TIP Number: SF-670099 Project Type: Bridge Replacement Date: 12/4/2018
NCDOT Contact. Galen Cail, PE Contractor! Designer. _Kyle Stoffer
Address: NCDOT Hydraulics Unit Address: HDR Engineering, Inc. of the Carolinas
1590 Mail Services Unit 555 Fayetteville Street, Suite 900
Raleigh, NC 27560 Raleigh, NC 27601
Phone: [phone] Phone: [phone]
Email: [e-mail] Email: [e-mail]
City/Town: County(ies): Orange
River Basin(s): Cape Fear CAMA County? No
Wetlands within Project Limits? No
-. Project Description
Project Length (lin. miles or feet): 0.114 miles Surrounding Land Use: Low Residential, Wooded
Proposed Project Existing'Site
Project Built-Upon Area (ac.) 0.4 ac. 0.3 ac.
Typical Cross Section Description: New Hope Church Road (SR 1723): 2 paved lanes (total 22' wide), 6' shoulder on each New Hope Church Road (SR 1723): 2 paved lanes (total 22' wide), 6' shoulder on
side (9' with guardrail), each side (9'with guardrail).
Annual Avg Daily Traffic (veh/hr/day): Design/Future: 5600 Year: 2025 Existing: 2800 Year: 2007
General Project Narrative: The North Carolina Department of Transportation (NCDOT) has proposed to replace Orange County Bridge#99 on New Hope Church Road (SR 1732) over New Hope Creek.
(Description of Minimization of Water The existing structure is a three span bridge (3@35') and is a reinforced concrete deck on I-Beams. The end bents are reinforced concrete caps on timber piles and the interior
Quality Impacts) bents are reinforced concrete posts and beams. The proposed structure is a single span (1@105'), 39" precast concrete box beam with 4' deep caps. This structure has been
designed to have as little environmental and surface water impacts as possible. 2:1 roadway fill slope will be used to minimize impacts.
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 15+09 RT to dissipate energy to provide a diffuse flow(non-
erosive sheet flow) in a wooded area. This diffused flow will run for a distance of 20'+/- before entering the buffer. In the southwest quadrant an existing roadside ditch outlets at
13+10 RT. The ditch outlets and becomes non-erosive sheet flow 200'+/_ before entering the buffer. In the northwest quadrant an existing roadside ditch will transition into a
Special Lateral 'V Ditch with Class B Rip Rap and outlets at 13+75 LT and becomes non-erosive sheet flow 160'+/- before entering the buffer. In the northeast quadrant an
existing roadside ditch will transition into a Special Lateral V Ditch with Class B Rip Rap and outlets at 17+00 LT and becomes non-erosive sheet flow 13'+/- before entering the
buffer. In the southeast quadrant an existing roadside ditch will transition into a Special Lateral 'V' Ditch with Class B Rip Rap and outlets at 16+94 RT and becomes non-
erosive sheet flow 45'+/- before entering the buffer. Due to the nature of low impact bridge replacement, the increases in stomlwater discharges (post vs pre condition) are
insignificant and the existing ditches do not need to be modified. Therefore, additional stormwater measures are not required. A temporary causeway will be utilized over New
Hope Creek to remove one interior bent.
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Surface Water Body (1): New Hope Creek NCDWR Stream Index No.: 16-41-1-(0.5)
NCDWR Surface Water Classification for Water Body Primary Classification: Water Supply V (WS-V)
Supplemental Classification: Nutrient Sensitive Waters (NSW)
Other Stream Classification: None
Impairments: None
Aquatic T&E Species? No Comments:
NRTR Stream ID: Buffer Rules in Effect: Jordan Lake
Project Includes Bridge Spanning Water Body? Yes Deck Drains Discharge Over Buffer? No Dissipator Pads Provided in Buffer? No
Deck Drains Discharge 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)