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Home My WebLink About20120358 Ver 1_Stormwater Info_20120425STORMWATER MANAGEMENT PLAN Project 45353 3 6 TIP# BD 5107E Orange County Project Engineer Jimmy L Terry PE Roadway Description This project consists of replacing Bridge #670076 over New Hope Creek on SR 1113 and improving the roadway bridge approaches The existing 56 4 x 22 5 bridge is structurally deficient and will be replaced with a new 92 25 x 30 bridge at the same location An off site detour will be utilized during construction Total project length is 455 linear feet The existing roadway travel lane width will be increased from 20 to 22 and a paved shoulder (vanes 2 to 4 ) will be added on both sides of the travel way Due to the paved shoulders and proposed structure the impervious surface area will be increased by approximately 0 09 acres The project drainage consists of two drop inlets and an outlet pipe with two elbows near station 11 +66 +/ This will outlet into an existing undisturbed roadside ditch The two existing ditches on the east side will be tapered out to outlet right before the designated Buffer Zones Both of these existing ditches will have a permanent np rap pad at the outlet to reduce velocities prior to entering the Buffer Zones Environmental Description This project is located in the Cape Fear River Basin and is subject to the Jordan I ake Buffer Rules New Hope Creek is classified as a WS V NSW stream at this location Existing wetlands exist at this location on the south side of the existing roadway There will be no impacts to these areas during construction Best Management Practices and Mayor Structures The primary goal for Best Management Practices (BMPs) is to prevent degradation of the state s surface waters by the location construction and operation of the highway system BMPs are activities practices and procedures taken to prevent or reduce stormwater pollution Due to the existing topography and existing drainage patterns all stormwater is discharged prior to entering the buffer areas II Required Items Checklist The proposed structure is a 92 25 long single span 39 box beam bridge with spill through abutments Approximately 455 linear feet of roadway is being widened including the bridge a Minimized to the extent hydraulically possible b The grade on the bridge carries the runoff to the west side Two inlets are proposed to pick up the runoff on west side at —L Sta 11 +66 +/ The inlets will discharge as far away from New Hope Creek buffers as reasonably possible on the north side into an existing undisturbed drainage ditch The total discharge from the proposed inlet is 0 4 cfs (Q10) No deck drains are warranted on this structure c Existing patterns were maintained with a minimal amount of additional stormwater added to the outfalls All outlets are ,lust outside of the buffer zones and all outlets have velocity controlling pads to reduce the flow prior to entering the buffers The roadway fill slopes will be vegetated using the latest seeding requirements under NCG 010000 General Construction Permit effective August 3 2011 All appropriate construction BMPs will be employed during bridge demolition and reconstruction d Due to right of way constraints and existing topography all roadside drainage ditches used a 4 1 front slope and a 2 1 back slope Existing back slopes vary from 1 1 to 2 1 This is an improvement to existing conditions All proposed roadside ditches outlets prior to entering the buffer zones Existing conditions carried the ditches to the top of bank locations F II 49�100,s"S" 110 r-. C:) C) o Lu U ui z cc LU tie 0 0 CL. LL. I I ED C�e Z9 viz 6fi7 � Z l OR C7 z2 ------------------- --------------------------------- o.q 2 M, IS I I ED C�e Z9 viz 6fi7 � Z l OR C7 z2 ------------------- ---------------------------------