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Home My WebLink About20230151 Ver 1_Bridge #141 Buffer Package_20230131 HjghWay North Carolina Department of Transportation °�°t f�rnrm�ntaa ° Highway Stormwater Program STORMWATER MANAGEMENT PLAN (Version 2.06;Released June 2016) FOR NCDOT PROJECTS WBS Element: 000141 TIP No.: County(ies): Alamance Page 1 of 1 General Project Information WBS Element: 000141 ITIP Number: Project Type: Other Date: 6/13/2022 NCDOT Contact: Jerry Parker Contractor/Desi ner: Galen Call Address: 1584 Yanceyville Street Address: 1020 Birch Ridge Dr. PO Box 14996 Raleigh,NC 27610 Greensboro,NC 27415-4996 Phone: 336 256-2063 1 Phone: 919 707-6711 Email:jparker@ncdot.gov Email:,gcail@ncdot.gov City/Town: Snow Camp Count ies: Alamance River Basin(s): Cape Fear CAMA County? No Wetlands within Project Limits? No Project Description Er Project Length(lin.miles or feet): 75 ft Surrounding Land Use: Rural/Woods Proposed Project Existing Site Project Built-Upon Area ac. 0.1 ac. 0.1 ac. Typical Cross Section Description: 10'travel lanes with 2'shoulders& 10'travel lanes with V shoulders 8'shoulder for future bike lane Annual Avg Daily Traffic(veh/hr/day): Design/Future: Year: Existing: Year: General Project Narrative: This project involves the replacement of an existing 25.5 foot bridge with a 25'-4"x 9'-5"aluminum box culvert with inlet/outlet sills and headwall and endwall. The existing (Description of Minimization of Water bridge has a timber deck and timber vertical abutments with steel 1-beams. The proposed culvert sills will be inset into the inlet and outlet approximately 2',and will have low Quality Impacts) flow notches to mimic the existing stream width. Upstream and downstream stream banks will be stabilized with Class II rip rap. Grassed shoulders and fill slopes will be provided with final roadway section. Waterbody Information Surface Water Body(1): Wells Creek NCDWR Stream Index No.: 16-28-1 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? INo I Deck Drains Discharge Over Buffer? INo Dissipator Pads Provided in Buffer? N/A Deck Drains Discharge Over Water Body? INo (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) I General Project Narrative) Bridge to Culvert Justification Alamance County Br#000141 SR 1005 Greensboro Chapel Hill Rd Wells Creek The project consists of replacing 25.5' long Bridge that has a Sufficiency Rating of 58.24 in Alamance County. The current structure was constructed with a timber deck and timber vertical abutments and steel beams in 1950. These structures typically have a life span of 50 years and this structure is 72 years old and has reached the end of its life cycle. The proposed structure consists of an Aluminum Box Culver with a single span of 25'-4"width by 9'-5" high culvert. This structure meets the hydrological requirements of the drainage area, slightly decreasing both the FEMA 100 Year and 50 Year design backwater. The aluminum culvert slightly increases the hydraulic opening area compared to the existing bridge. The use of this type of structure will reduce the construction time from 120 days to 60 days as compared to that of a bridge. The culvert is anticipated to function similar to that of the existing vertical abutment bridge relative to flow depths, flow area,velocities and flow width through the structure. Flow depths in the culvert will be maintained by use of low flow sills at the inlet and outlet of the culvert. The sills will be notched 1 foot in depth to mimic the effective low flow width of the existing stream channel up and downstream. Culverts have lower construction and maintenance cost over the life cycle of the structure as compared to a bridge. Current budget constraints require us to take the most economical option that meets environmental and safety concerns. Typically,the length of a bridge will be much longer than that of a culvert's width. Increasing the bridge length creates several issues that must be overcome. If a bridge is utilized there must be at least four feet of clearance under the bridge to allow access for maintenance workers at the abutment. At crossings where new bridges are recommended,this often requires NCDOT to raise the roadway grade to maintain or improve clearance under the bridge. Raising the roadway grade can potentially impact crossing hydraulics. For storm events that overtop the existing road, raising the road grade typically results in increases to that events backwater. Wells Creek is located in a FEMA Limited Detailed Study and the 100 Year backwater is regulated. Although a Limited Study does allow for increases in the 100 Year backwater without having to provide a CLOMR (Conditional Map Revision)to FEMA, it is typical NCDOT practice to avoid increases in backwater, where practical, due to potential liabilities/impacts to upstream properties. Per the FEMA model and our analysis, Wells Creek does overtop Greensboro Chapel Hill Road SR 1005 during a 100 Year event at this crossing therefore maintaining the existing roadway grade with a culvert benefits the crossing by maintaining, or slightly reducing,the backwater. Smaller streams in the Piedmont area are often best suited for culverts to minimize raising the roadway grade. Justification for bridge to culvert: • The basin drainage area (3.1 sq miles) and estimated discharges are compatible with the hydraulic performance of a culvert structure. And as mentioned,typically prefer culverts due to longer service life and reduced maintenance vs a bridge. • The proposed 25'-4" wide culvert and 25.5' long bridge (with vertical timber abutments) have similar hydraulic type openings and properties. Hydraulic function including backwater, outlet velocities, structure opening,flow depths and flow widths, etc will remain similar, if not slightly improved. • The inlet and outlet channels look stable. So we would anticipate the same with culvert. PROJECT REFERENCE NO. SHEET NO. P R O E C T DES SHEET NO. J ROADWAY DESIGN HYDRAULICS ENGINEER ENGINEER I I I INCOMPLE E PLANS w°1" xrou ewnuw. mxu uaa. -NOT OFR— 1.ACOOISITION II i wii..s ..oe. uw„ xwsu nsnroon " I I I ouneso as.rn I I I DOCUMENT NOT CONSIDERED FINAL UNLESS ALL SIGNATURES COMPLETED I I I o «<o."sE moe I I I o«<ou. pox"non ESE m. III I o�..e on n oEu n,o.o "e s .... nroen ,.Dose ".any .rne eno� vs, I I I I II I na.n on ss A I I I I I I I I I I I I I II I I I I Le11MW1 I I I I I I I I I I II I `wuuma I I I I I I I Z I O � I I I I � I , j � \ I � \ // \\$R boo 2368) / i SR ALAMANCE COUNTY \`\ I SNOW CAMP LAT /LONG = 35D8989/ - 79D4569 G 61' PROJECT REFERENCE NO. SHEET NO. RNJ SHEET NO. ROADWAY DESIGN HYDRAULICS BUFFER IMPACTS PERMIT ENGINEER ENGINEER INC®MPLE E F]LAN9 POR /W AWUIeIT10N 100, o' DOCUMENT NOT CONSIDERED FINAL UNLESS ALL SIGNATURES COMPLETED �xxxx ALLOWABLE IMPACTS ZONE 1 GRAPHIC SCALE ALLOWABLE IMPACTS ZONE 2 _ > L1 V z Z O Z l7 N O �- 10+50 a P1W & 40' LT 1 ti` e 25'-4" x 9'-5" ABC w/HW & EW al— EEK �e! Oy�WE�I GR CLASS II RIP RAP EST 80 T NS g1�� 30 SY GEOTE E BIZ 9+75 j j �titi RNd & 40' LT rm rm x x z z c-) c-) :�u :�u � y � PROJECT REFERENCE NO. SHEET NO. RN! SHEET NO. ROADWAY DESIGN HYDRAULICS ENGINEER ENGINEER III BUFFER IMP S PET ,�Q1 8L5 � I I I / �J l / v INC®MPLE E F]LAN9 h ` I I o POR /W AWUIeIT10N U 578O \ �a \\JI 11 / DOCUMENT NOT CONSIDERED FINAL 579 e /\I �N I I I n U UNLESS ALL SIGNATURES COMPLETE D ALL�V LE IMPACTS'9Z6NE 1 574_ y L_579/ GRAPHIC ALE 574 580 tS zONE 2 II o o/ c co f (51y � o / Z / N by / -419'x��5" B _/H W E _�- _pss « ( I 1 - 581 - _—_ 577 57 CLASS II RIP BSRAP —�` \ r ✓�� _ -- --- EST 80 T NS \ �� J --�\ / \� C �0-&Y—EQL t \a-z I IM N / \ _580 58p J / +75 \ j / _ LT 580 rA —Oss—� 4-V( E -9 -..j 7 I 'Al 0 Avil Of BANK o I ullic --I Yr 51AI 4, EB.,--11., ... - r 57 U 1 11 1 1 ---------- 'I rh� I I I -1-4 1 A 0 7 J-- I I I I I I -]03-----g7- SA, BUFFER IMPACTS SUMMARY IMPACT BUFFER TYPE ALLOWABLE MITIGABLE REPLACEMENT STATION ROAD PARALLEL ZONE 1 ZONE 2 TOTAL ZONE 1 ZONE 2 TOTAL ZONE 1 ZONE 2 SITE NO. STRUCTURE SIZE/TYPE (FROM/TO) CROSSING BRIDGE IMPACT (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) 1 Culvert/Constr Access 13+80 To 15+70-L-LT X 1658.0 512.0 2170.0 TOTALS: 1658.0 512.0 2170.0 N.C.DEPT.OF TRANSPORTATION DIVISION OF HIGHWAYS ALAMANCE COUNTY PROJECT: 000141 6/13/2022 SHEET OF ev.May 2006