HYDROLOGIC AND HYDRAULIC REPORT PROPOSED CULVERT STRUCTURES SR 194, SECTION 10

Transcription

1 HYDROLOGIC AND HYDRAULIC REPORT PROPOSED CULVERT STRUCTURES SR 194, SECTION 10 RACETRACK ROAD CULVERT OVER THE SPRING RUN & GREEN SPRINGS ROAD CULVERT OVER AN UNNAMED TRIBUTARY TO SPRING RUN BERWICK TOWNSHIP ADAMS COUNTY, PENNSYLVANIA JULY 2007 benesch PROJECT NO benesch Prepared By: alfred benesch & company Engineers Surveyors Planners 1550 Pond Road Suite 201 Allentown, PA Phone: Fax: Chicago, IL Kenosha, WI Lansing MI Pottsville, PA

2 TABLE OF CONTENTS PAGE ABSTRACT...1 PROFESSIONAL ENGINEER STATEMENT & SEAL...2 PURPOSE...3 SITE DATA...3 ALTERNATIVE ANALYSIS...5 HYDROLOGIC ANALYSIS...6 HYDRAULIC ANALYSIS...8 EROSION AND SEDIMENTATION CONTROL MEASURES...15 TRAFFIC CONTROL...15 RISK ASSESSMENT...15 WASTE OF DEMOLITION MATERIAL...15 SCOUR INVESTIGATION...15 WETLANDS DELINEATION...16 SUMMARY...17 SUMMARY DATA SHEETS...18

3 APPENDICES APPENDIX A - MAPS LOCATION MAPS USDA SOILS MAPS & SOIL TYPES NRCS GEOLOGY MAP APPENDIX B - PHOTOGRAPHS APPENDIX C - FEMA FLOOD MAP AND STUDY DATA APPENDIX D - DRAINAGE AREA MAPS - CONEWAGO CREEK WATERSHED MAP APPENDIX E - PEAK FLOW CALCULATIONS WRIR NFF (RACETRACK ROAD) EFM-2 (GREEN SPRINGS ROAD) APPENDIX F - FLOOD FREQUENCY CURVE APPENDIX G - STAGE DISCHARGE FREQUENCY CURVE alfred benesch & company APPENDIX H - HYDRAULIC CALCULATIONS RACETRACK ROAD o HEC-RAS OUTPUT AND CROSS SECTIONS EXISTING CONDITION PROPOSED CONDITION TEMPORARY CONDITION GREEN SPRINGS ROAD o HY-8 MODEL EXISTING CONDITION PROPOSED CONDITION APPENDIX I - PLANS AND PROFILE HYDROLOGIC AND HYDRAULIC PLANS PROFILE OF SR0194 CONCEPTUAL T.S. & L. PLANS & ESTIMATE EROSION & SEDIMENTATION PLAN (Pending) APPENDIX J - PRELIMINARY SCOUR CALCULATIONS APPENDIX K - CORRESPONDENCE APPENDIX L - ENVIRONMENTAL DOCUMENTATION (PNDI) APPENDIX M - EXCERPT FROM THE WETLANDS DELINEATION APPENDIX N - CD WITH HEC-RAS FILES & COLOR HYDROLOGIC AND HYDRAULIC PLAN APPENDIX O - EXISTING HALF SIZE PLAN RPT.HH.SR doc

4 ABSTRACT SR194 CULVERTS AT RACETRACK ROAD & GREEN SPRINGS ROAD BERWICK TOWNSHIP, ADAMS COUNTY The proposed project is located on SR194 Section 10 in Berwick Township, Adams County. There are two culverts in the project area which are discussed in this report. The existing bridge at Racetrack Road (Station 97+50) crossing the Spring Run will be replaced; and the existing culvert at Green Springs Road (Station 55+85) crossing a tributary to Spring Run will be extended. The existing structure at Station is a single span cast-in-place concrete slab bridge built in The existing structure opening has an average underclearance of 2.5 at the creek with approximately a clearspan. The existing structure at Station is a combination cast-inplace concrete arch bridge and box culvert extension. The existing structure opening is 7.8 x 4.3. The scope of work is to replace the existing bridge at Station with a precast concrete box culvert and to extend the existing culvert at Green Springs Road with a precast or cast-in-place concrete box culvert. This is due to the headwalls being within the clear zone resulting in a safety hazard. The replacement culvert at Station will have a clear span length of 20-0 and a rise of 4-0 depressed 1-0 with 7-0 long wingwalls. The extended culvert at Station will have new skewed concrete box sections with a clear span length of 8-0 and a depth of 4-6. The Federal Emergency Management Agency (FEMA) has performed a detailed flood insurance study for the Spring Run in Berwick Township. However, the limit of detailed study only extends to the downstream end of the structure and data for the study was not available. The Army Corps of Engineers HEC-RAS Version computer program was used to determine water surface profile for the proposed culvert at Station and the FHWA Hydraulic Program HY-8 (May, 1987) is used to analyze the culvert extension at Station Scour at the openings to the culvert at Station will be controlled through the placement of R-8 rip-rap rock from the edge of each wingwall to a distance of 5-0 past the edge of the proposed concrete wingwalls. The rip-rap rock replaces existing material in the stream and does not reduce the waterway openings for the structure. Scour at the openings to the culvert at Station will be controlled through the placement of R-8 rip-rap rock from the edge of each wingwall to a distance of 5-0 past the edge of the proposed concrete wingwalls. The rip-rap rock replaces existing material in the stream and does not reduce the waterway openings for the structure. USGS MAP LOCATION (from right hand corner of Hanover Quadrangle) Racetrack Road Culvert = 15 ¼ from right hand corner, 3/8 from top Green Springs Road Culvert = 15 ¼ from right hand corner, 2 ¼ from top ADAMS COUNTY 1

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6 PURPOSE The purpose of this study is to determine the feasibility of constructing a new precast concrete box culvert to replace the existing cast-in-place concrete slab bridge over Spring Run at Station and also to extend the existing box culvert at Station along SR 194. This is to accommodate the betterment project of the SR194 corridor through Penn Township, Berwick Township and Abbottstown Borough. The proposed horizontal and vertical alignment of SR194 will not be modified. The design parameters used for the Hydrologic and Hydraulic Analysis incorporate criteria established by the Pennsylvania Department of Transportation (PENNDOT) and Pennsylvania Department of Environmental Protection (PADEP) and are based on sound engineering judgment and principles. SITE DATA 1) Racetrack Road Culvert (Station 97+50) The proposed structures are located in Berwick Township, Adams County. At Station 97+50, Racetrack Road, the existing structure is upstream of the confluence of Beaver Creek and the Spring Run (see Location Map Appendix "A"). The existing structure is a cast-in-place concrete single span slab bridge with a clear span and an average vertical clearance of 2.5 feet. A field view was conducted by alfred benesch & company by Mr. Gregory Kuklinski on January 17, Upstream of the existing bridge, the stream flows through meadows which are part of a residential development. Downstream of the bridge, the stream flows between a pasture on the south side of the creek and a heavily wooded area on the north side of the creek. Photographs of the existing site are included in Appendix B. Based on aerial photographs, approximately 1 mile downstream of the existing Racetrack Road bridge, Spring Run flows under SR 194 at German Street in Abbottstown Borough. The German Street bridge is a concrete T-beam bridge with a 23-0 span and an approximate underclearance of 5-0. Upstream of the SR194 Bridge, Spring Run splits with both streams flowing under Maple Grove Road. The structure closest to SR194 on Maple Grove Road is a concrete slab bridge located outside of the study area. It is located approximately 0.60 miles upstream of the proposed culvert location and has a 14-0 span with a 7-0 vertical clearance. The second upstream structure at Beaver Creek Road is a dual 7-6 CMP culvert located approximately 0.5 miles upstream. Pictures of the upstream and downstream structures can be found in Appendix B. According to PADEP Chapter 93, Spring Run is a tributary to Beaver Creek which is listed as a warm water fishery (WWF). Since Spring Run is a tributary to Beaver Creek, it has the same designation. Spring Run is neither a PA Fish and Boat Commission approved trout water nor listed as a wild trout water. 3

7 The flow in Spring Run is continuous year round. There is no visible evidence of any damage caused by ice or drifting debris at the site. The Flood Insurance Study for Berwick Township states the following on p.5: The elevation of a high-water mark from Tropical Storm Eloise in September 1975 at the SR194 bridge as feet. The Eloise flood overtopped and breached the dam that forms Heeler s Pond which is located southwest of the Beaver Creek Church. Overtopping of State Route 194 and flooding of one home, east of the highway, was reported near Beaver Creek Church. There are no known flood control projects or resources, which affect the flow in Spring Run. There are no other known factors that will impact the water stages at the proposed structure. Upstream of the existing structure, the creek meanders between pastures. A 5-0 strip of tall weeds, timber and brush is located along the top of the streambanks. The far out-of-bank regions consist of short grass, residential buildings and farming structures. Some minor erosion is observed at the bends in the stream. At the SR194 bridge, large amounts of debris is observed at the bend in the creek. There is a tree on the streambank that has the potential of falling in the stream during the next storm event (See Photo in Appendix B ). Due to the sharp bend upstream of the bridge, there is a 2-0 deep scour hole at the south wingwall with observed scour. At the bridge, deterioration was seen in the concrete slab on both the upstream and downstream ends. The downstream end has considerable amounts of concrete that are chipped away with corroded reinforcing steel exposed. Debris is observed stuck between the reinforcing bar and the remaining concrete slab. Under the south side of the bridge, there are large deposits of silt, gravel and small pebbles which have not washed out from a large storm event. No fish were observed in the stream and the average depth of water is 9. Downstream of the existing structure, the creek meanders between heavy woods and brush on the north side and pasture fields on the south side. At the bridge, gravel, pebbles and silt block approximately 30% of the hydraulic opening. This obstruction is not getting washed away due to the sharp bend in the stream approximately 20 downstream. At this location, debris is observed including small trees that have fallen across the creek. Approximately 2 of stream bank erosion is on the south bank. Approximately 200 downstream, erosion is observed at the location where a swale empties into the creek. 2) Green Springs Road Culvert (Station 55+85) The proposed structure is located in Berwick Township, Adams County, at Station on Green Springs Road. The existing structure is located upstream of the confluence of Spring Run and the unnamed Tributary to the Spring Run (see Location Map Appendix "A"). The existing structure is a combination cast-in-place concrete arch and box culvert. The structure has a clear span of 7-9 and an average clear height of 4-4 on the upstream side and 4-6 on the downstream side. A field view was conducted by alfred benesch & company by Mr. Gregory Kuklinski on January 17, Upstream of the existing bridge, the stream flows adjacent to Green Springs Road in front of the Orchard Acres Development. Downstream of the bridge, the stream flows between a private 4

8 residence along SR194 and a church parking lot before emptying into Spring Run. Photographs of the existing site are included in Appendix B. Upstream flow is generated by the Orchard Acres Development stormwater system and a stream that flows under Green Springs Road. The upstream box culvert under Green Springs Road is a 4-6 span with a 2-1 clear height. Downstream of the split between the swale from the stormwater system and the stream under Green Springs Road, there is a 10-6 span stone pedestrian bridge with a 4-0 vertical clearance. There are no downstream structures between the Tributary and Spring Run. According to PADEP Chapter 93, the Unnamed Tributary to Spring Run is a tributary to Beaver Creek which is listed as a warm water fishery (WWF). Since Spring Run is a tributary to Beaver Creek, it has the same designation. Spring Run is neither a PA Fish and Boat Commission approved trout water nor listed as a wild trout water. The flow in the Unnamed Tributary to Spring Run is continuous year round. There is no visible evidence of any damage caused by ice or drifting debris at the site. This stream is not located in the Flood Insurance Study for Berwick Township. There are no known flood control projects or resources, which affect the flow in the Unnamed Tributary. There are no other known factors that will impact the water stages at the proposed structure. Upstream of the SR194 culvert, the stream is channelized between a strip of grass adjacent to Green Springs Road and a grass meadow. Heavy erosion (approximate 4 tall stream banks) is observed at locations of curves in the stream with exposed roots on numerous trees. Downstream of the pedestrian bridge, Pachysandra and small lighted miniature houses line the top of the bank. Although no high water marks were seen on the trees or the mailbox, based on the exposure of the tree roots, it appears that all the flow is channelized within the streambanks with no out-of-bank flow. The flow is constant in the stream with an approximate 3-4 depth. As per a resident on Green Springs Road, the flow has only reached the road during Hurricane Agnes in Just upstream of the existing bridge, there are two concrete steps to take the flow under SR194. The first step measured 9 tall and the second step was 15 tall with a 1 scour hole below it. A swale adjacent to SR194 was flowing with water from the highway drainage. Much of the bottom slab of the culvert has eroded away with mostly silt and pebbles lining the stream. No fish are observed in the stream. Downstream of the existing bridge, the stream flow is channelized until it reaches Spring Run. High water marks were seen on the adjacent garage approximately 1 above the stream bank (4 above the bottom of stream.) Stone and large rocks line the streambed. Erosion was seen at the confluence with Spring Run with exposed tree roots on the corner of the two streams. Preliminary Line and Grade approval is pending on this project. ALTERNATIVE ANALYSIS As part of the Conceptual Type Size & Location Submission, one culvert option was developed and reviewed by alfred benesch & company for the proposed culvert at Station

9 Precast Concrete Box Culvert with Precast Flared Wingwalls - $175,000 See Appendix I for a preliminary cost estimate. HYDROLOGIC ANALYSIS The Federal Emergency Management Agency (FEMA) has performed a Flood Insurance Study for all jurisdictions in Adams County. According to FEMA's study (FIRM Map # dated May 19, 1987, and FIRM Map # dated November 4, 1981), Spring Run is located in the 100-year Flood Boundary and the 500-year Flood Boundary with detailed flood elevations. The location of Spring Run on the FEMA FIRM Maps is shown in Appendix C. The Unnamed Tributary to Spring Run is not located on the FEMA FIRM Maps. HEC-2 data for Spring Run was requested from Michael Baker, Jr. Inc on November 2, On December 21, 2006, Daniel Horner from Baker stated in an that the original study completed in February, 1980 was not found. The only HEC-2 data that was found was for Cross-sections B-J for the 1986 restudy model which are located downstream of the project (See Appendix K for the ). As per the PADEP, the design flows in the Flood Insurance Study and existing stream cross-sections from the field survey will be utilized. To determine the difference in datum, the USGS Corpscon v6.0.1 program was used to find the adjustment between the 1929 NGVD datum (FEMA survey) and the NAVD88 vertical datum (current survey.) The program output adjusts the NGVD29 elevation to 0.69 higher than the NAVD88 vertical datum. The existing 100 year flood elevation as shown in the Berwick Township FIS study is at the SR194 bridge. The change in datum yields an elevation of which will be compared to the HEC-RAS 100 year flood elevation in the Hydraulic Analysis section of this report. PENNDOT Publication 13M (DM-2) Change No. 1 released June 16, 2006 contains general guidelines regarding the selection criteria for regional regressions equations for estimates of peak flows at ungauged sites. In the 1987 Berwick Township Flood Insurance Study, flows for Spring Run were computed using logarithmic equations as set forth in the study. Since the drainage area to the existing structure at Station (2.30 mi 2 ) is greater than 1.5 mi 2, DM-2 Section 10.6 states that the method USGS WRIR Techniques for Estimating Magnitude and Frequency of Peak Flows for Pennsylvania Streams should be utilized. Water-Resources Investigations Report is a regression analysis of stream flow data for Pennsylvania drainage basins ranging in size from approximately 1.5 mi 2 up to approximately 2000 mi 2. USGS WRIR has been incorporated into the USGS s National Flood Frequency (NFF) program which includes a National Urban Equation which adjusts the results of rural regression equations to account for urbanization. Peak discharges are generated for the 10, 25, 50, 100 & 500 year flood occurrences from the WRIR program. The drainage area to the existing structure at Station in Region A is 2.30 mi 2 (1472 acres). Based on the USGS mapping, 37.8% of the area consists of forest cover and 15% of the area consists of urban development with 0.6% of the area controlled by lakes, swamps and reservoirs. As per the Pennsylvania Department of Conservation and Natural Resources Map 15, the project 6

10 location is not underlain with limestone or dolomite rocks (See map in Appendix E.) The drainage area for the existing culvert at Station is 0.33 mi 2 (213 acres) which is less than 1.5 mi 2. Per DM-2, the method EFH2 is used to determine peak flow data. EFH2 determines peak discharge by procedures contained in SCS s Engineering Field Handbook. This method is applied to stream in rural watersheds between 1 acre and 2000 acres. Calculations for the flows are located in Appendix E. FEMA Flow Summary Spring Run Station Q FLOW Q FLOW CFS CFS WRIR Flow Summary Spring Run Station Q FLOW Q FLOW CFS CFS ** ** Determined from PSU-IV EFH2 Flow Summary Unnamed Tributary to Spring Run Station Q FLOW Q FLOW CFS CFS The USDA Natural Resources Conservation Service (Web Soil Survey 1.1) states that the soil composition along SR194 consists of various different soils which are located on the soils map in Appendix A. and are described in the Soil Survey of Adams County. The geology within the study area consists of the New Oxford Formation which does not contain any Dolomite or Limestone. The Geology Map is located in Appendix A. A flood frequency curve and stage discharge frequency curve are plotted using the data for each culvert. These curves are included in Appendices G and H, respectively. Elevations from field survey are used to generate stream cross-sections for the proposed culvert at Station PENNDOT s DM-2 Table states that the minimum return period for a minor arterial system is the 25 year storm. This storm event will be modeled to evaluate velocity and scour calculations. As 7

11 per Chapter 105 Subchapter C (Dam Safety & Waterway Management Section ) of the Pennsylvania Code, a structure located in a floodway that is delineated on a FEMA map, no increase in the 100-year water surface elevation (0.00 ) will be permitted for the culvert at Station Also, this culvert is not considered a stream enclosure since it is less than 100 feet long and therefore is not designed to pass the flows from a flood of 100-year frequency. Chapter 105 Subchapter C (Dam Safety & Waterway Management Section ) of the Pennsylvania Code states that for a structure located in a floodway that is delineated on a FEMA map, no increase in the 100-year water surface elevation will be permitted. This will also be modeled and checked. HYDRAULIC ANALYSIS 1) Racetrack Road Culvert (Station 97+50) The proposed improvements to the existing structure include the removal of the existing bridge and installation of a new precast reinforced concrete box culvert under SR194. The roadway will be widened from 28 to 33-1 to accommodate a wider right shoulder. To compare the existing and proposed conditions for the stream crossings, the May 2005 Version of HEC-RAS River Analysis System from the U. S. Army Corps of Engineers is used. Data for the program was obtained by importing the cross sections based upon field survey completed by benesch for this project. Both the input and output data from the HEC-RAS Analyses are included in Appendix H. The survey data has been entered for cross sections at the following distances: Upstream: 525 Downstream: 400 All of the cross-sections in HEC-RAS are cut looking downstream left to right. The existing and proposed cross-sections can be seen on the Hydrologic and Hydraulic Plan Sheet contained in Appendix I. To make the plan easier to read, a color PDF file has been placed on the CD in Appendix N. Based on the field view, the following Manning s n coefficients are utilized in the existing and proposed HEC-RAS models based on the site data on Pages 3-4. Land Use Manning s n Coefficient Pasture with no brush and short grass Clean, winding channel with some pools and shoals Scattered brush, pasture & farmland Medium to dense brush along streambanks Medium to dense brush, heavy stand of timber

12 For the proposed model, a Manning s coefficient of 0.03 is used between the end of the wingwalls where streambed material will be accumulated on top of the R-8 rip-rap rock. Per PENNDOT BD- 632M Sheet 5/11, the precast culvert will be depressed 1-0. The information for the proposed culvert is input into the HEC-RAS Program and the capacity and proposed water surface elevations are determined utilizing cross-sections taken upstream and downstream of the proposed culvert. For the first cross-section, a normal depth flow using the slope of the existing stream (0.85%) is assumed and calculations then precede upstream assuming a mixed flow profile and steady, gradual varied flow. The existing stream elevations are computed using the calculated flows, and established roughness coefficient. It is the intent of this project to construct a structure that does not adversely impact the surrounding area. The proposed SR194 box culvert will have a greater hydraulic opening than the existing bridge opening: EXISTING HYDRAULIC OPENING: 49.4ft 2 (HEC-RAS) PROPOSED HYDRUALIC OPENING: 60.0 ft 2 Energy losses at the culvert are computed in two (2) parts. First, due to flow contraction at the upstream side and flow expansion at the downstream side of the structure, the computed standard step calculations assume an expansion loss coefficient of 0.5 and a contraction loss coefficient of 0.3 between the contraction and expansion reaches. The expansion reach is at Station for the existing model and Station for the proposed model. The contraction reach is at Station for both the existing and proposed models. All other cross-sections assume an expansion loss coefficient of 0.3 and a contraction loss coefficient of 0.1. In the existing and proposed HEC-RAS model, ineffective flow areas are established at the edge of the culvert to convey water through the culvert. The proposed wingwalls for both culverts are at a 30 degree flare. Ineffective flow areas are also established at cross-sections that are between the existing and proposed wingwalls and the expansion or contraction reaches. In the existing and proposed models, ineffective flow is placed at the upstream bridge/culvert stations slightly lower than the high chord (top of road). At the downstream station, ineffective flow elevation is placed slightly lower than the low chord elevation for the same reason as upstream. These locations were chosen so that when the water surface rises above the ineffective flow elevation, the flow would be considered effective as wier flow. At these two cross-sections, the permanent toggle is not turned on so that overtopping of the road is permitted. The locations of ineffective flow are located on the Plan Sheet in Appendix I. This project will not alter the permanent alignment of the stream upstream and downstream of the proposed culvert. Downstream of the proposed culvert, the stream alignment will be straightened out to match the existing stream eliminating the curve and preventing further stream bank erosion. The proposed culvert baseline will tie into the existing stream approximately 10 downstream of the edge of the rip-rap rock per BD-632M. Upstream of SR194, the proposed culvert will eliminate some of the curve in the stream thus causing less scour holes and erosion with the ability to clean out the stream. The culvert is to be set at the same slope as the existing stream (0.85%) and is to be 9

13 depressed 1-0. For the location of the proposed structure, see the Conceptual T.S.&L. Plans in Appendix I. In accordance with DM-2 Chapter 10.10, the structure will incorporate 12 baffles along the bottom of the culvert to allow for ease of fish passage. The stream banks will be sloped to match existing conditions upstream and downstream. These improvements are indicated on the plans in Appendix I. Two (2) temporary 42 corrugated metal pipes (CMP) will be placed on the north side of the existing bridge during construction to contain the flow of the Spring Run. They will each be 115 long and placed on the north side of the existing bridge. There will be a rise in water surface elevations upstream of the existing bridge during construction for the 2.33 year storm event, but the flow will be contained in the banks of the existing stream and will not overtop the roadway. At stream cross-sections along Spring Run, all water surface elevations for the 100-year flood for the proposed structure are within the 0.00 allowable rise in water surface elevations as stated in PA Code Chapter 105 and FEMA regulations. The maximum drop in water surface elevations occur at Station which is 0.91 lower than existing. There is only one location which has a rise in water surface elevations for the 25 year storm and that is at the first cross-section downstream at Station which is 0.01 above existing. This rise is acceptable since it occurs within the PennDot Right-of-Way and will not impede on any adjacent structures or residences. There are a few cross-sections for the 25 and 100 year storms that have small increases in velocity. At the SR194 bridge, the water surface elevation for the 100 year storm is which is within 3 of the FIS Study adjusted elevation of (See page 6). This is within tolerance of a HEC-RAS model that closely matches the FEMA study. The HEC-RAS model shows that the existing bridge is overtopped by the 10 year storm (EL ) and the 25 year design storm (EL ). With the greater hydraulic opening, the proposed culvert prevents the overtopping of the road for the 10 year storm (EL ) and will continue to overtop during the 25 year storm (EL ). The low point on the road occurs upstation of the culvert and has an elevation of There are no errors in the HEC-RAS model and there are various warnings asking for additional cross-sections which is due to the bridge overtopping. Cross-sections were taken between 50 and 150 apart based on the horizontal alignment of the stream. Based on the analysis, a 20 x 4 box culvert is acceptable for Spring Run. The tables on Page 11 and 12 summarize the water surface elevations and velocities at various stream cross sections for the 25-year design storm and the 100-year FEMA storm. 10

14 Water Surface Elevation Summary 25-year Design storm SR194 Racetrack Road 25 Year Flood Section Existing (FT) Proposed (FT) Change (FT) EXISTING BRIDGE & PROPOSED EXISTING BRIDGE & PROPOSED - CULVERT CULVERT Channel Velocity Summary 25-year Design storm SR194 Racetrack Road 25 Year Flood Section Existing (FT/S) Proposed (FT/S) Change (FT/S) EXISTING BRIDGE & PROPOSED EXISTING BRIDGE & PROPOSED - CULVERT CULVERT

15 Water Surface Elevation Summary 100-year FEMA storm SR194 Racetrack Road 100 Year Flood Section Existing (FT) Proposed (FT) Change (FT) EXISTING BRIDGE & PROPOSED EXISTING BRIDGE & PROPOSED - CULVERT CULVERT Channel Velocity Summary 100-year FEMA storm SR194 Racetrack Road 100 Year Flood Section Existing (FT/S) Proposed (FT/S) Change (FT/S) EXISTING BRIDGE & PROPOSED EXISTING BRIDGE & PROPOSED - CULVERT CULVERT

16 2) Green Springs Road Culvert (Station 55+85) This culvert is being widened to move the headwalls outside the clear zone for the roadway, thus eliminating the need for guiderail. The proposed improvements to the existing culvert include the extension of the culvert with a 3-0 cast-in-place concrete transition section at a 15 degree skew and one 9-0 precast or cast-in-place concrete segment upstream. Since the skew is less than or equal to 15 degrees, no loss coefficients are needed in the proposed internal cross-sections (FHWA Publication HDS5, Hydraulic Design of Highway Culverts, p.146). There will be a 3-0 cast-inplace transition section and a 9-0 precast or cast-in-place concrete segment. The downstream culvert extension will be an 8-0 (span) x 4-6 (height). To compare the existing and proposed conditions for the stream crossings, the May 1987 version of FHWA Hydraulic Program HY-8 is used to analyze the culvert extension at Station Data for the program was obtained by using field survey information completed by benesch for this project. Both the input and output data from the HY-8 are included in Appendix H. HY-8 is used for this stream since the stream is channelized with no out-of-bank flow. As per PENNDOT DM-2 p for culverts with cross-sectional areas greater than 30 ft 2, the HW/D ratio must be less than 1.2. The upstream HW/D for the existing culvert is 1.17 for the 25 year flood event and the proposed culvert is 1.09 due to an improved inlet condition from the existing. The HY-8 anaylsis shows that the 25 year design storm is in an inlet controlled condition and does overtop SR194. The low point on the upstream side of the road is at elevation based on the field survey. The existing 25 year design storm has an elevation of and the proposed elevation is The elevation along Green Springs Road in the vicinity of SR194 is which is slightly higher than overtopping storm of All flow for the 25 year design storm will be contained within the stream channel and will not overtop the roadway. This confirms what the resident on Green Springs Rd. said that the road has only been overtopped once which was in In order to construct the culvert extensions and wingwalls, stream diversion devices will be used to stop flow around the work area during low flow events. The stream diversion will be constructed of sandbag dikes, concrete barriers or other approved methods. Based on the analysis, the proposed 8-0 x 4-6 box culvert extensions are acceptable for the Unnamed Tributary to Spring Run. For the HY-8 analysis, see Appendix H. 13

17 Water Surface Elevation Summary SR194 Green Springs Road Storm Existing (FT) Proposed (FT) Change (FT) Event * * * Velocity Summary SR194 Green Springs Road Storm Event Existing (FT/S) Proposed (FT/S) Change (FT/S) * * * * = Per HY-8., the box culvert flows full and is overtopped by the 100 year flood event 14

18 EROSION AND SEDIMENTATION CONTROL MEASURES alfred benesch & company Permanent and temporary erosion and sedimentation control measures shall be provided in accordance with the contract drawings, details and specifications. The Engineer will order such measures to be taken during the life of the contract to control water pollution through the use of berms, dikes, jute matting, soil retention blankets, gravel, mulches, grasses, and other erosion control devices. The Erosion and Sedimentation Control Plan and Report for this structure have been approved by the Adams County Conservation District. Temporary pollution control provisions will be coordinated with permanent erosion control features specified in the contract to the greatest extent practical to assure economical, effective, and continuous erosion control throughout the construction and post-construction period. The contractor will be required to contact the Adams County Conservation District and the Southcentral Regional Office of the Fish & Boat Commission 72 hours prior to any earthmoving activities within the stream. TRAFFIC CONTROL 1) Racetrack Road Culvert (Station 97+50) The existing roadway will be controlled by a temporary traffic signal allowing one-way traffic across the bridge during phased construction. A more detailed Traffic Control Plan is completed as part of the Design Field View Plans. 2) Green Springs Road Culvert (Station 55+85) All work for the culvert extension is outside the roadway limits. Temporary guiderail will be installed to protect the work zone. RISK ASSESSMENT Hydraulic calculations are performed for the 100-year flood in order to assess the risk of flood damage caused by the proposed structures. Based upon the calculations, it is anticipated that there is no risk involved with both proposed culverts because there are no rise in water surface elevations for the 100-year flood. Therefore, there is no increase in hazard to people or property by the construction of the proposed culvert. WASTE OF DEMOLITION MATERIAL The Contractor is required to deposit waste demolition material from the structures in an approved upland area not designated as wetlands or flood plain. 15

19 SCOUR INVESTIGATION In order to ensure the stability of the structures during storm events, an investigation into the anticipated scour depth for the 100-year storm event is completed. Per PENNDOT Publication No. 15 "Design Manual Part 4 (DM4) Structures", PENNDOT Publication 218 "Standards for Bridge Design (BD-600 Series)" and based on the downstream velocity at the structure, measures are taken to minimize the potential for scour to occur. Therefore scour protection is based upon the stream velocities for the proposed conditions. As per DM4, a scour analysis for a box culvert is not required. DM-4 Section has an equation which is used to size the rip-rap needed at the outlet of the culvert 1) Racetrack Road Culvert (Station 97+50) On Spring Run, a maximum velocity of FPS occurs at the downstream side of the culvert and 4.66 FPS occurs at the upstream side during the 100-year storm. R-8 rip-rap is placed on the upstream and downstream side of the structure as determined with Section of PENNDOT DM- 4. This rip-rap replaces existing material in the stream and does not reduce the waterway opening for the proposed structure. The rip-rap will be placed at a depth of 4-0. The rip-rap will start at the edge of the proposed wingwalls and extend for a distance of 5-0 past the proposed wingwalls. A rip-rap sizing calculation has been completed in Appendix J. 2) Green Springs Road Culvert (Station 55+85) On the Unnamed Tributary to Spring Run, a maximum velocity of FPS occurs during the 100- year storm. R-8 rip-rap is placed on the upstream and downstream side of the structure as determined with Section of PENNDOT DM-4. This rip-rap replaces existing material in the stream and does not reduce the waterway opening for the proposed structure. The rip-rap will be placed at a depth of 4-0. The rip-rap will start at the edge of the proposed wingwalls and extend for a distance of 5-0 past the proposed wingwalls. A rip-rap sizing calculation has been completed in Appendix J. WETLANDS DELINEATION A wetland and watercourse identification/delineation and functional assessment report was completed by Skelly & Loy on October 23, As per Sheet 11 of the report, An offsite review of the USFWS NWI Map revealed no wetland habitats within or immediately adjacent to the study areas. However an on-site field investigation identified and delineated three wetlands (Wetlands A through C) in the northern study area (Racetrack Road), and one wetland (Wetland D) in the southern study area (Green Springs Road) It is further noted on Sheet 12 of the report, It should be noted that the small size of these wetlands greatly limits the effectiveness of Wetlands A, B & C to provide these functions and values to any quantifiable level. On Sheet 13 of the report, Wetland D provides minimal functions and values to the surrounding environment. As excerpted from the CEE Document dated 11/22/05, According to the USFWS NWI Mapping, 16

20 there are three freshwater forested/scrub wetlands along Route 194. The largest is located on the western side of Route 194 just north of Racetrack Road. The second wetland is located on the opposite side of Route 194 south of the first wetland about 1000 feet. The third wetland is 1000 feet south of the second wetland. Therefore since the wetlands that were observed are noted as providing minimal functions and value and a total disturbed acreage of 0.01 acres, the construction of the culverts will not negatively impact the surrounding environment. An excerpt from the draft Mitigation Report can be found in Appendix M. SUMMARY It can be seen from the preceding analysis and attached calculations that the construction of the proposed culverts have no adverse impacts on the stream profile for Spring Run and the Unnamed Tributary to Spring Run. Temporary fill to be placed in the stream includes the construction of a temporary stream diversion device or other approved methods to divert flow during construction. Permanent fill to be placed in both streams include the placement of R-8 rip-rap along the openings. The rip-rap will replace existing material in the stream and will not reduce the waterway opening for the proposed structure. These activities will be covered by a GP-11 Permit meeting the requirements of PADEP Chapter 105 Water Obstruction and Encroachment Permit and the U.S. Army Corps of Engineers Section 404 Permit. 18

21 Summary Data Sheet Spring Run & Racetrack Road Location Data County Adams Municipality Berwick Township Location - U.S.G.S. Map Abbottstown State Route SR Latitude N " Station Center Line Bridge Longitude W " Segment / Offset 230/011 Present ADT: Year: 2005 Future ADT: Year: 2025 River Basin (US-ACOE) Susquehanna Channel Data Stream Name Spring Run Side Slope Left: 4/1 (Estimate) (looking downstream) Right: 4/1 (Estimate) Stream Slope 0.85% (Average) Type of Channel Silt, gravel, pebbles Normal Stream Flow Depth 9 Average Top Width 26.4 Stream Bed Elevation at Inlet Average Bottom Width 8.3 Stream Bed Elev. Exact Dist Stream Bed Elev. Exact Dist ~500' upstream Elevation ~500' downstream Elevation Average Stream Channel Depth 2.2 High Water Gage Height & Date N/A Hydrology Other: Hydrology Method Used FEMA WRIR NFF PSU-IV Drainage Area 2.30 square miles 2.30 square miles 2.30 square miles Q2 (CFS) Q10 (CFS) Q25 (CFS) Q50 (CFS) Q100 (CFS) Q500 (CFS) Hydraulics EXISTING STRUCTURE PROPOSED STRUCTURE Bridge Type RC Slab Bridge Bridge Type RC Precast Box Culvert Clear Span - Centerline Clear Span - Centerline 20-0 Clear Span - Normal Clear Span - Normal 20-0 Skew 90 degrees Skew 90 degrees Minimum Underclearance (creek) 1.8 Minimum Underclearance (creek) 3.0 Length of Channel Impacted 28-0 Length of Channel Impacted 65-0 Number of Spans 1 Number of Spans 1 Low Chord Elevation (DS) Low Chord Elevation (DS) Hydraulic Method Used HEC-RAS HEC-RAS Hydraulic Method Used STA STA Return Period* Q WSE Velocity Return Period* Q WSE Velocity (Design Storm) (Design Storm) (FEMA Storm) (FEMA Storm) Overtopping Overtopping High Water Marks NONE High Water Marks NONE *Indicate Design Return Period with a at the appropriate year. Or if year is not shown, fill in Design Return Period in blank row. 18

22 Summary Data Sheet Unnamed Tributary to Spring Run & Green Springs Road Location Data County Adams Municipality Berwick Township Location - U.S.G.S. Map Abbottstown State Route SR Latitude N " Station Center Line Bridge Longitude W " Segment / Offset 200/2915 Present ADT: Year: 2005 Future ADT: Year: 2025 River Basin (US-ACOE) Susquehanna Channel Data Stream Name Unnamed Tributary Side Slope Left: 2/1 (Estimate) to Spring Run (looking downstream) Right: 2/1 (Estimate) Stream Slope 3.11% (Average) Type of Channel Silt, gravel, pebbles Normal Stream Flow Depth 4 Average Top Width 15 Stream Bed Elevation at Inlet Average Bottom Width 5 Stream Bed Elev. Exact Dist. 490 Stream Bed Elev. Exact Dist. 180 ** ~500' upstream Elevation ~500' downstream Elevation Average Stream Channel Depth 4 High Water Gage Height & Date N/A Hydrology Hydrology Method Used EFM-2 Drainage Area 0.33 square miles Q2 (CFS) 55 Q10 (CFS) 204 Q25 (CFS) 254 Q50 (CFS) 329 Q100 (CFS) 493 Hydraulics EXISTING STRUCTURE PROPOSED STRUCTURE EXTENSIONS Bridge Type Cast-in-Place Box Culvert / Arch Bridge Type RC Precast Box Culvert Clear Span - Centerline 7-9 Clear Span - Centerline 8-0 Clear Span - Normal 7-9 Clear Span - Normal 8-0 Skew 90 degrees Skew 90 degrees Minimum Underclearance (creek) 4.3 Minimum Underclearance (creek) 4.5 Length of Channel Impacted 30-0 Length of Channel Impacted 76-0 Number of Spans 1 Number of Spans 1 Low Chord Elevation (DS) Low Chord Elevation (DS) Hydraulic Method Used HY-8 Hydraulic Method Used HY-8 Return Period* Q WSE Velocity Return Period* Q WSE Velocity (Design Storm) (Design Storm) *** *** *** *** Overtopping Overtopping High Water Marks NONE High Water Marks NONE Temporary or Permanent Fill NONE *Indicate Design Return Period with a at the appropriate year. Or if year is not shown, fill in Design Return Period in blank row. ** At confluence of Unnamed Tributary to the Spring Run and the Spring Run *** Box flows full and overtops the roadway per HY-8 19