20120359 Ver 1_Stormwater Info_20120425

STORMWATER MANAGEMENT PLAN
Project 45353 3 6 TIP# BD 5107E
Guilford County
Project Engineer Jimmy L Terry PE
Roadway Description
This protect consists of replacing Bridge #400231 over North Prong Stinking Quarter Creek on
SR 1005 and improving the roadway bridge approaches The existing 89 7 x 23 4 bridge is
structurally deficient and will be replaced with a new 132 5 x 33 bridge at the same location
An off site detour will be utilized during construction Total project length is 545 linear feet
The existing roadway travel lane width will remain the same and a paved shoulder (varies 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 10 acres 'I he prod ect
drainage consists of one drop inlet and cross pipe near station 18 +90 +/ as well as a standard
grass Swale replacing an existing 12' RCP in the northeast quadrant of the bridge Due to the
need for guardrail protection along the south approach, an existing driveway had to be relocated
This relocation requires additional fill and a replacement of an existing 36 drive pipe
Environmental Description
This project is located in the Cape Fear River Basin and is subject to the Jordan Lake Buffer
Rules North Prong Stinking Quarter Creek is classified as a WS V, NSW stream at this
location
Best Manaixement 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 limited right of way and existing drainage patterns there is not a suitable
location for structural BMP
11 Required Items Checklist
The proposed structure is a 132 5 long three span 21 cored slab bridge with spill through
abutments Approximately 545 linear feet of roadway is being widened including the bridge
a Mimmized to the extent hydraulically possible
b The grade on the bridge carries the runoff to the northwest side A single inlet is
proposed to pick up the runoff on west side of the road at —L Sta 18 +90 +/ The
inlet will discharge as far away from North Prong Stinking Quarter Creek buffers as
reasonably possible on the east side Being able to outlet at this location and

eliminating the existing 12 drive pipe and replacing with a grass swale allowed
approximately 40 linear feet of grass swale between the outlet and Buffer Zone 2
The total discharge from the proposed inlet is 0 6 cfs (Q10) This number assumes
that the deck drains are clogged 100% for design purposes Deck drain slots through
the proposed bridge rail will be required at this site along the west side of the
proposed structure A Class II Rip Rap pad will be placed along the outfalls of the
deck drains to eliminate scouring potential
c Due to the existing ditch along the east side and the large drainage area from offsrte,
a preformed scour hole would not work at this site The outlet from the drop inlet
carrying the bridge discharge was placed as far as possible without impacting the
need for additional guardrail The grass swale will be constructed with 3 1 slopes
and vegetated according to the latest BMP design guidelines Other BMP s would
cause too much impact to the adjacent properties 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 All proposed vegetated roadside ditches are 3 1 slope or flatter

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