This report provides the results of a detailed Level II analysis of scour potential at structure \nRANDVT00120042 on State Highway 12 crossing the Third Branch White River, \nRandolph, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the \nsite, including a quantitative analysis of stream stability and scour (U.S. Department of \nTransportation, 1993). A Level I study is included in Appendix E of this report. A Level I \nstudy provides a qualitative geomorphic characterization of the study site. Information on \nthe bridge available from VTAOT files was compiled prior to conducting Level I and Level \nII analyses and can be found in Appendix D.
\nThe site is in the Green Mountain physiographic division of central Vermont in the town of \nRandolph. The 61.9-mi2\n drainage area is in a predominantly rural drainage basin. In the \nvicinity of the study site, the left and right banks have moderate tree cover with residential \nand commercial buildings on the overbank areas.
\nIn the study area, the Third Branch White River has a sinuous channel with a slope of \napproximately 0.013 ft/ft, an average channel top width of 133 ft and an average channel \ndepth of 5 ft. The predominant channel bed material is gravel with a median grain size ( \nD50) of 49.6 mm (0.163 ft). Bank material is sand and gravel (D50 is 3.08 mm or 0.010 ft). \nThe geomorphic assessment at the time of the Level I site visits on July 8, 1994 and \nDecember 13, 1994, indicated that the reach has experienced vertical degradation. A drop \nstructure has been constructed downstream of the bridge to prevent further degradation. In \naddition to the degradation of the stream bed, there is local pier scour at the bridge site as \nwell. At the nose of the pier in the main channel, the bed is approximately three feet below \nthe mean thalweg and two feet below the bottom of the pier footing.
\nThe State Highway 12 crossing of the Third Branch White Riveris a 220-ft-long, two-lane\nbridge consisting of four concrete spans. The maximum span length is 57 ft. (Vermont \nAgency of Transportation, written commun., July 29, 1994). The bridge is supported by \nvertical, concrete abutments and three concrete piers. The toe of the left abutment is at the \nchannel edge. The toe of the right abutment is set back on the right over-bank. The roadway \ncenterline on the structure has a slight horizontal curve; however, the main channel is \nskewed approximately 5 degrees to the bridge. Additional details describing conditions at \nthe site are included in the Level II Summary and Appendices D and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1993). Scour depths were \ncalculated assuming an infinite depth of erosive material and a homogeneous particle-size \ndistribution. The scour analysis results are presented in tables 1 and 2 and a graph of the \nscour depths is presented in figure 8.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96187","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., and Weber, M.A., 1996, Level II scour analysis for Bridge 42 (RANDVT00120042) on State Highway 12, crossing Third Branch White River, Randolph, Vermont: U.S. Geological Survey Open-File Report 96-187, iv, 28 p., https://doi.org/10.3133/ofr96187.","productDescription":"iv, 28 p.","numberOfPages":"33","costCenters":[],"links":[{"id":178504,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96187.GIF"},{"id":279419,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0187/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Randolph","otherGeospatial":"Third Branch White River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.875 ], [ -72.75,44.0 ], [ -72.625,44.0 ], [ -72.625,43.875 ], [ -72.75,43.875 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a6153","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240244,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Weber, Matthew A.","contributorId":41483,"corporation":false,"usgs":true,"family":"Weber","given":"Matthew","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240245,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49789,"text":"ofr96231 - 1996 - Level II scour analysis for Bridge 25 (HARDTH00420025) on Town Highway 42, crossing Lamoille River, Hardwick, Vermont","interactions":[],"lastModifiedDate":"2013-12-11T12:59:53","indexId":"ofr96231","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-231","title":"Level II scour analysis for Bridge 25 (HARDTH00420025) on Town Highway 42, crossing Lamoille River, Hardwick, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nHARDTH00420025 on town highway 42 crossing the Lamoille River, Hardwick, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). A Level I study is included in Appendix E of this report. A Level I study provides \na qualitative geomorphic characterization of the study site. Information on the bridge \navailable from VTAOT files was compiled prior to conducting Level I and Level II \nanalyses and can be found in Appendix D.
\nThe site is in the Green Mountain physiographic division of north-central Vermont in the \ntown of Hardwick. The 119-mi2\n drainage area is in a predominantly rural basin. In the \nvicinity of the study site, the left banks are covered by pasture and (or) fields. The right \nbank of Lamoille River is adjacent to Vermont Route 15 near the north edge of the Lamoille \nRiver valley.
\nIn the study area, the Lamoille River has a sinuous channel with a slope of approximately \n0.0004 ft/ft, an average channel top width of 89.0 ft and an average channel depth of 8.0 ft. \nThe predominant channel bed material is sand and gravel (D50 is 22.4 mm or 0.0733 ft). In \ngeneral, the banks have sparse or no woody vegetative cover and the reach was noted to be \nlaterally unstable at the time of the Level I site visit on July 25, 1995. The Level II work \nwas completed on 07/27/95 and the site was revisited on August 16, 1995, just after the \nAugust 5-6, 1995 flood on the Lamoille River. Findings from this follow-up visit are \npresented in Appendix G.
\nThe town highway 42 crossing of the Lamoille Riveris a 62-ft-long, two-lane bridge \nconsisting of one 60-foot steel- beam span with a concrete deck, supported by vertical \nabutments with wingwalls on upstream and downstream sides (Vermont Agency of \nTransportation, written commun., August 24, 1994). The bridge is supported by vertical \nabutments with wingwalls on upstream and downstream sides. The channel is not skewed to \nthe opening and the opening-skew-to-roadway is 0 degrees.
\nA scour hole 3.0 ft deeper than the mean thalweg depth was observed 5 feet upstream from \nthe bridge face at mid-channel during the Level I assessment. Additional details describing \nconditions at the site are included in the Level II Summary and Appendices D and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1993).\nTotal scour at a highway crossing is comprised of three components: 1) long-term \naggradation or degradation; 2) contraction scour (due to reduction in flow area caused by a \nbridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total \nscour is the sum of the three components. Equations are available to compute scour depths \nfor contraction and local scour and a summary of the results follows.
\nContraction scour for all modelled flows was 0.0 ft. Abutment scour ranged from 6.5 ft to \n15.6 ft and the worst-case abutment scour occurred at the 500-year discharge. Scour depths \nand depths to armoring are summarized on p. 14 in the section titled “Scour Results”. \nScour elevations, based on the calculated depths are presented in tables 1 and 2; a graph of \nthe scour elevations is presented in figure 8 Scour depths were calculated assuming an \ninfinite depth of erosive material and a homogeneous particle-size distribution.
\nFor all scour presented in this report, “the scour depths adopted [by VTAOT] may differ \nfrom the equation values based on engineering judgement” (Richardson and others, 1993, p. \n21, 27). It is generally accepted that the Froehlich equation (abutment scour) gives \n“excessively conservative estimates of scour depths” (Richardson and others, 1993, p. 48). \nMany factors, including historical performance during flood events, the geomorphic \nassessment, and the results of the hydraulic analyses, must be considered to properly assess \nthe validity of abutment scour results.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96231","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ayotte, J., 1996, Level II scour analysis for Bridge 25 (HARDTH00420025) on Town Highway 42, crossing Lamoille River, Hardwick, Vermont: U.S. Geological Survey Open-File Report 96-231, iv, 31 p., https://doi.org/10.3133/ofr96231.","productDescription":"iv, 31 p.","numberOfPages":"36","costCenters":[],"links":[{"id":179107,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96231.GIF"},{"id":279394,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0231/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Hardwick","otherGeospatial":"Lamoille River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.5,44.5 ], [ -72.5,44.625 ], [ -72.375,44.625 ], [ -72.375,44.5 ], [ -72.5,44.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a8043","contributors":{"authors":[{"text":"Ayotte, Joseph D. jayotte@usgs.gov","contributorId":1802,"corporation":false,"usgs":true,"family":"Ayotte","given":"Joseph D.","email":"jayotte@usgs.gov","affiliations":[{"id":466,"text":"New England Water Science Center","active":true,"usgs":true}],"preferred":false,"id":240261,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49813,"text":"ofr96385 - 1996 - Level II scour analysis for Bridge 33 (BRIDTH00050033) on Town Highway 5, crossing the North Branch Ottauquechee River, Bridgewater, Vermont","interactions":[],"lastModifiedDate":"2013-12-10T15:18:13","indexId":"ofr96385","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-385","title":"Level II scour analysis for Bridge 33 (BRIDTH00050033) on Town Highway 5, crossing the North Branch Ottauquechee River, Bridgewater, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nBRIDTH00050033 on town highway 5 crossing the North Branch Ottauquechee River, \nBridgewater, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the \nsite, including a quantitative analysis of stream stability and scour (U.S. Department of \nTransportation, 1993). Results of a Level I scour investigation also are included in \nAppendix E of this report. A Level I investigation provides a qualitative geomorphic \ncharacterization of the study site. Information on the bridge, gleaned from Vermont Agency \nof Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II \nanalyses and is found in Appendix D.
\nThe site is in the Green Mountain section of the New England physiographic province of \ncentral Vermont in the town of Bridgewater. The 5.01-mi2\n drainage area is in a \npredominantly rural and forested basin. In the vicinity of the study site, the downstream \nbanks are forested and the upstream banks have dense woody brush; the upstream right \noverbank is an open field.
\nIn the study area, the North Branch Ottauquechee River has an incised, sinuous channel \nwith a slope of approximately 0.017 ft/ft, an average channel top width of 30 ft and an \naverage channel depth of 3 ft. The predominant channel bed materials are gravel and cobble \nwith a median grain size (D50) of 83.2 mm (0.273 ft). The geomorphic assessment at the \ntime of the Level I and Level II site visit on November 3, 1994, indicated that the reach was \nstable. Also at the time of the site visit, there was considerable backwater at the bridge site \ndue to a three foot tall beaver dam 40 feet downstream. The beaver dam was assumed \ndestroyed by flood flow and was ignored in the analyses.
\nThe town highway 5 crossing of the North Branch Ottauquechee Riveris a 25-ft-long, onelane bridge consisting of one 23-foot steel-beam span with a timber deck (Vermont Agency \nof Transportation, written communication, August 25, 1994). The bridge is supported by \nvertical, concrete abutments with wingwalls. The channel is skewed approximately 20 \ndegrees to the opening while the opening-skew-to-roadway is 10 degrees.
\nA scour hole 1.0 ft deeper than the mean thalweg depth was observed along the right \nabutment and upstream right wingwall during the Level I assessment. Scour protection \nmeasures at the site include type-2 stone fill (less than 36 inches diameter) at the ends of all \nthe wingwalls except the upstream left which has \ntype-3 stone fill (less than 48 inches diameter). Additional details describing conditions at \nthe site are included in the Level II Summary and Appendices \nD and E.
\n\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1993). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.
\nContraction scour for all modelled flows ranged from 0.0 to 0.7 ft. The worst-case \ncontraction scour occurred at the incipient-overtopping discharge, which was less than the \n100-year discharge. Abutment scour ranged from 5.3 to 7.2 ft. The worst-case abutment \nscour occurred at the 500-year discharge. Additional information on scour depths and \ndepths to armoring are included in the section titled “Scour Results”. Scoured-streambed \nelevations, based on the calculated scour depths, are presented in tables 1 and 2. A crosssection of the scour computed at the bridge is presented in figure 8. Scour depths were \ncalculated assuming an infinite depth of erosive material and a homogeneous particle-size \ndistribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96385","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., and Song, D.L., 1996, Level II scour analysis for Bridge 33 (BRIDTH00050033) on Town Highway 5, crossing the North Branch Ottauquechee River, Bridgewater, Vermont: U.S. Geological Survey Open-File Report 96-385, iv, 30 p., https://doi.org/10.3133/ofr96385.","productDescription":"iv, 30 p.","numberOfPages":"35","costCenters":[],"links":[{"id":179495,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96385.GIF"},{"id":279355,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0385/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Bridgewater","otherGeospatial":"North Branch Ottauquechee River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.625 ], [ -72.75,43.75 ], [ -72.625,43.75 ], [ -72.625,43.625 ], [ -72.75,43.625 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b19e4b07f02db6a7c44","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240305,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Song, Donald L.","contributorId":107335,"corporation":false,"usgs":true,"family":"Song","given":"Donald","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240306,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49814,"text":"ofr96386 - 1996 - Level II scour analysis for Bridge 29 (CRAFTH00550029) on Town Highway 55, crossing the Black River, Craftsbury, Vermont","interactions":[],"lastModifiedDate":"2013-12-10T14:58:25","indexId":"ofr96386","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-386","title":"Level II scour analysis for Bridge 29 (CRAFTH00550029) on Town Highway 55, crossing the Black River, Craftsbury, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCRAFTH00550029 on town highway 55 crossing the Black River, Craftsbury, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the New England Upland section of the New England physiographic province \nof north-central Vermont in the town of Craftsbury. The 24.7-mi2\n drainage area is in a \npredominantly rural and forested basin. In the vicinity of the study site, the banks have \nwoody vegetation coverage except for the upstream left bank and the downstream right \nbank, which have more brush cover than trees.
\nIn the study area, the Black River has an incised, sinuous channel with a slope of \napproximately 0.01 ft/ft, an average channel top width of 41 ft and an average channel \ndepth of 5.5 ft. The predominant channel bed material is sand and gravel (D50 is 44.7 mm or \n0.147 ft). The geomorphic assessment at the time of the Level I and Level II site visit on \nJune 7, 1995, indicated that the reach was stable.
\nThe town highway 55 crossing of the Black Riveris a 32-ft-long, one-lane bridge consisting \nof one 28-foot span steel stringer superstructure with a timber deck (Vermont Agency of \nTransportation, written communication, August 4, 1994). The bridge is supported by \nvertical, concrete abutments with wingwalls. The channel is skewed approximately 40 \ndegrees to the opening while the opening-skew-to-roadway is 10 degrees.
\nA scour hole 2 ft deeper than the mean thalweg depth was evident at mid-channel \nimmediately downstream of the bridge during the Level I assessment. The only scour \nprotection measure at the site was type-1 stone fill (less than 12 inches diameter) on the \nupstream right bank and road approach embankment. Additional details describing \nconditions at the site are included in the Level II Summary and Appendices D and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.
\nContraction scour for all modelled flows ranged from 0.9 to 1.4 ft. The worst-case \ncontraction scour occurred at the 100-year discharge. Abutment scour ranged from 12.1 to \n15.5 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96386","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Boehmler, E.M., and Degnan, J.R., 1996, Level II scour analysis for Bridge 29 (CRAFTH00550029) on Town Highway 55, crossing the Black River, Craftsbury, Vermont: U.S. Geological Survey Open-File Report 96-386, iv, 47 p., https://doi.org/10.3133/ofr96386.","productDescription":"iv, 47 p.","numberOfPages":"52","costCenters":[],"links":[{"id":178613,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96386.GIF"},{"id":279354,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0386/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Craftsbury","otherGeospatial":"Black River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.5 ], [ -72.75,43.625 ], [ -72.625,43.625 ], [ -72.625,43.5 ], [ -72.75,43.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b19e4b07f02db6a7f28","contributors":{"authors":[{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240308,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Degnan, James R. 0000-0002-5665-9010 jrdegnan@usgs.gov","orcid":"https://orcid.org/0000-0002-5665-9010","contributorId":498,"corporation":false,"usgs":true,"family":"Degnan","given":"James","email":"jrdegnan@usgs.gov","middleInitial":"R.","affiliations":[{"id":466,"text":"New England Water Science Center","active":true,"usgs":true},{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240307,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49815,"text":"ofr96387 - 1996 - Level II scour analysis for Bridge 36 (BRIDTH00050036) on Town Highway 5, crossing Bridgewater Hollow Brook, Bridgewater, Vermont","interactions":[],"lastModifiedDate":"2013-12-10T14:46:43","indexId":"ofr96387","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-387","title":"Level II scour analysis for Bridge 36 (BRIDTH00050036) on Town Highway 5, crossing Bridgewater Hollow Brook, Bridgewater, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nBRIDTH00050036 on town highway 5 crossing Bridgewater Hollow Brook, Bridgewater, \nVermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including \na quantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the Green Mountain section of the New England physiographic province of \ncentral Vermont. The 3.60-mi2\n drainage area is in a predominantly forested basin. In the \nvicinity of the study site, the banks have dense woody vegetation coverage.
\nIn the study area, Bridgewater Hollow Brook has an incised, sinuous channel with a slope \nof approximately 0.028 ft/ft, an average channel top width of 24 ft and an average channel \ndepth of 4 ft. The predominant channel bed material is cobble (D50 is 196 mm or 0.644 ft). \nThe geomorphic assessment at the time of the Level I and Level II site visit on November 2, \n1994, indicated that the reach was stable.
\nThe town highway 5 crossing of Bridgewater Hollow Brook is a 30-ft-long, one-lane bridge \nconsisting of one 27-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, August 25, 1994). The bridge is supported by vertical, concrete abutments \nwith wingwalls. The channel is skewed approximately 30 degrees to the opening and the \nopening-skew-to-roadway is also 30 degrees.
\nThe scour protection measures at this site were sparse type-2 stone fill (less than 36 inches \ndiameter) along both abutments, upstream wingwalls, and the downstream left wingwall \nand type-1 stone fill (less than 12 inches diameter) along the downstream right wingwall.\nAdditional details describing conditions at the site are included in the Level II Summary \nand Appendices D and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.
\nThere was no contraction scour for all modelled flows. Abutment scour ranged from 4.9 to \n7.0 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96387","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., and Boehmler, E.M., 1996, Level II scour analysis for Bridge 36 (BRIDTH00050036) on Town Highway 5, crossing Bridgewater Hollow Brook, Bridgewater, Vermont: U.S. Geological Survey Open-File Report 96-387, iv, 30 p., https://doi.org/10.3133/ofr96387.","productDescription":"iv, 30 p.","numberOfPages":"35","costCenters":[],"links":[{"id":178614,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96387.GIF"},{"id":279353,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0387/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Bridgewater","otherGeospatial":"Bridgewater Hollow Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.625 ], [ -72.75,43.75 ], [ -72.625,43.75 ], [ -72.625,43.625 ], [ -72.75,43.625 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a6446","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240309,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240310,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49816,"text":"ofr96388 - 1996 - Level II scour analysis for Bridge 25 (BRNAVT00120025) on State Highway 12, crossing Locust Creek, Barnard, Vermont","interactions":[],"lastModifiedDate":"2013-12-10T13:29:17","indexId":"ofr96388","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-388","title":"Level II scour analysis for Bridge 25 (BRNAVT00120025) on State Highway 12, crossing Locust Creek, Barnard, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nBRNAVT00120025 on State Highway 12 crossing Locust Creek, Barnard, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). A Level I study is included in Appendix E of this report. A Level I study provides \na qualitative geomorphic characterization of the study site. Information on the bridge \navailable from VTAOT files was compiled prior to conducting Level I and Level II \nanalyses and can be found in Appendix D.
\nThe site is in the Green Mountain physiographic division of central Vermont in the town of \nBarnard. The 11.6-mi2\n drainage area is in a predominantly rural and forested basin. In the \nvicinity of the study site, the banks have woody vegetation coverage.
\nIn the study area, Locust Creek has a sinuous channel with a slope of approximately 0.023 \nft/ft, an average channel top width of 49 ft and an average channel depth of 4 ft. The \npredominant channel bed material is cobble (D50 is 109 mm or 0.359 ft). The geomorphic \nassessment at the time of the Level I and Level II site visits on September 23 and December \n16, 1994, indicated that the reach was stable.
\nThe State Highway 12 crossing of Locust Creek is a 41-ft-long, two-lane bridge consisting \nof one 39-foot concrete slab type superstructure (Vermont Agency of Transportation, \nwritten communication, August 23, 1994). The bridge is supported by vertical, concrete\nabutments with wingwalls. The channel is skewed approximately 30 degrees to the opening \nwhile the opening-skew-to-roadway is 45 degrees.
\nA scour hole 1 ft deeper than the mean thalweg depth was observed along a bedrock outcrop \nnear the upstream left wingwall during the Level I assessment. The scour protection \nmeasures in place at the site are type-1 stone fill (less than 12 inches diameter) along the left \nabutment, upstream right bank, and both downstream banks; type-2 stone fill (less than 36 \ninches diameter) at the downstream side of the right road approach and upstream left bank; \ntype-3 stone fill (less than 48 inches diameter) at the upstream end of the upstream right \nwingwall and downstream end of downstream left wingwall; type-5 (wall/ artificial levee) \nat the upstream end of the upstream left wingwall. Additional details describing conditions \nat the site are included in the Level II Summary and Appendices D and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1993). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.
\nContraction scour for all modelled flows ranged from 0.0 to 1.4 ft. The worst-case \ncontraction scour occurred at the 100-year discharge. Abutment scour ranged from 8.5 to \n20.9 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1993, p. 48). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96388","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ivanoff, M.A., and Weber, M.A., 1996, Level II scour analysis for Bridge 25 (BRNAVT00120025) on State Highway 12, crossing Locust Creek, Barnard, Vermont: U.S. Geological Survey Open-File Report 96-388, iv, 28 p., https://doi.org/10.3133/ofr96388.","productDescription":"iv, 28 p.","numberOfPages":"33","costCenters":[],"links":[{"id":178615,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96388.GIF"},{"id":279352,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0388/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Barnard","otherGeospatial":"Locust Creek","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.75 ], [ -72.75,43.875 ], [ -72.625,43.875 ], [ -72.625,43.75 ], [ -72.75,43.75 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a8084","contributors":{"authors":[{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240311,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Weber, Matthew A.","contributorId":41483,"corporation":false,"usgs":true,"family":"Weber","given":"Matthew","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240312,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49817,"text":"ofr96389 - 1996 - Level II scour analysis for Bridge 14 (CLARTH00010014) on Town Highway 1, crossing Cold River, Clarendon, Vermont","interactions":[],"lastModifiedDate":"2013-12-10T14:39:54","indexId":"ofr96389","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-389","title":"Level II scour analysis for Bridge 14 (CLARTH00010014) on Town Highway 1, crossing Cold River, Clarendon, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCLARTH00010014 on town highway 1 crossing the Cold River, Clarendon, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). A Level I study is included in Appendix E of this report. A Level I study provides \na qualitative geomorphic characterization of the study site. Information on the bridge \navailable from VTAOT files was compiled prior to conducting Level I and Level II \nanalyses and can be found in Appendix D.
\nThe site is in the Taconic Section of the New England physiographic province in westcentral Vermont in the town of Clarendon. The 36.2-mi2\n drainage area is in a predominantly \nrural basin. In the vicinity of the study site, the surface cover is primarily pasture, except for \nthe right bank upstream which is forested.
\nIn the study area, the Cold River has a sinuous channel with a slope of approximately 0.02 \nft/ft, an average channel top width of 104 ft and an average channel depth of 3 ft. The \npredominant channel bed material is cobble with a median grain size (D50) of 103 mm \n(0.339 ft). The geomorphic assessment at the time of the Level I and Level II site visit on \nApril 27, 1995, indicated that the reach was laterally unstable. This assessment was due to \nthe cut-banks and the local anabranching occurring upstream of the bridge.
\nThe town highway 1 crossing of the Cold River is a 80-ft-long, two-lane bridge consisting \nof one 77-foot span (Vermont Agency of Transportation, written communication, March \n13, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The left \nabutment and upstream wingwalls are protected by type-2 stone fill (less than 36 inches \ndiameter). The channel is skewed approximately 10 degrees to the opening while the \nopening-skew-to-roadway is 15 degrees. Additional details describing conditions at the site \nare included in the Level II Summary and Appendices D and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1993). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.
\nContraction scour for modelled flows ranged from 0.0 to 0.6 ft. Abutment scour ranged \nfrom 17.4 to 23.3 ft. The worst-case contraction and abutment scour occurred at the 500-\nyear discharge. Additional information on scour depths and depths to armoring are included \nin the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated \nscour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the \nbridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of \nerosive material and a homogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1993, p. 48). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96389","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 14 (CLARTH00010014) on Town Highway 1, crossing Cold River, Clarendon, Vermont: U.S. Geological Survey Open-File Report 96-389, iv, 36 p., https://doi.org/10.3133/ofr96389.","productDescription":"iv, 36 p.","numberOfPages":"41","costCenters":[],"links":[{"id":178616,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96389.PNG"},{"id":279351,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0389/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Clarendon","otherGeospatial":"Cold River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.0,43.5 ], [ -73.0,43.625 ], [ -72.875,43.625 ], [ -72.875,43.5 ], [ -73.0,43.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a82c6","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240313,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49818,"text":"ofr96390 - 1996 - Level II scour analysis for Bridge 12 (BRAITH00230012) on Town Highway 23, crossing Ayers Brook, Braintree, Vermont","interactions":[],"lastModifiedDate":"2013-12-10T14:35:08","indexId":"ofr96390","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-390","title":"Level II scour analysis for Bridge 12 (BRAITH00230012) on Town Highway 23, crossing Ayers Brook, Braintree, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nBRAITH00230012 on town highway 23 crossing Ayers Brook, Braintree, Vermont (figures \n1–8). A Level II study is a basic engineering analysis of the site, including a quantitative \nanalysis of stream stability and scour (U.S. Department of Transportation, 1993). A Level \nI study is included in Appendix E of this report. A Level I study provides a qualitative \ngeomorphic characterization of the study site. Information on the bridge available from \nVTAOT files was compiled prior to conducting Level I and Level II analyses and can be \nfound in Appendix D.
\nThe site is in the Green Mountain physiographic province of central Vermont in the town of \nBraintree. The 18.8-mi2\n drainage area is in a predominantly rural watershed. In the vicinity \nof the study site, the surface cover of the left and right banks is pasture.
\nIn the study area, Ayers Brook has a meandering channel with a slope of approximately \n0.003 ft/ft, an average channel top width of 46 ft and an average channel depth of 5 ft. The \npredominant channel bed material is sand and gravel (D50 is 6.15 mm or 0.0202 ft). The \ngeomorphic assessment at the time of the Level I and Level II site visit on November 16, \n1994, indicated that the reach was laterally unstable. Also at the time of the site visit, there \nwas considerable backwater at the bridge site due to a beaver dam downstream. The beaver \ndam was ignored in the analyses.
\nThe town highway 23 crossing of Ayers Brook is a 28-ft-long, one-lane bridge consisting of \none 23-foot span (Vermont Agency of Transportation, written communication, August 24, \n1994). The bridge is supported by vertical timber cribwork abutments with wingwalls on \nthe upstream and downstream sides of the right abutment. The lower half of the right \nabutment and wingwalls are constructed of laid-up stone. The right abutment and wingwalls \nare also protected by stone fill. The channel is skewed approximately 45 degrees to the \nopening while the opening-skew-to-roadway is only 5 degrees. Additional details \ndescribing conditions at the site are included in the Level II Summary and Appendices\nD and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1993). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.
\nContraction scour for all modelled flows ranged from 4.2 to 9.4 ft. The worst-case \ncontraction scour occurred at the incipient-overtopping discharge which was less than the \n100-year discharge. Abutment scour ranged from 4.3 to 17.5 ft. The worst-case abutment \nscour occurred at the 500-year discharge. Additional information on scour depths and \ndepths to armoring are included in the section titled “Scour Results”. Scoured-streambed \nelevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were \ncalculated assuming an infinite depth of erosive material and a homogeneous particle-size \ndistribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1993, p. 48). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96390","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 12 (BRAITH00230012) on Town Highway 23, crossing Ayers Brook, Braintree, Vermont: U.S. Geological Survey Open-File Report 96-390, iv, 30 p., https://doi.org/10.3133/ofr96390.","productDescription":"iv, 30 p.","numberOfPages":"35","costCenters":[],"links":[{"id":178729,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96390.PNG"},{"id":279350,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0390/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Braintree","otherGeospatial":"Ayers Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.875 ], [ -72.75,44.0 ], [ -72.625,44.0 ], [ -72.625,43.875 ], [ -72.75,43.875 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a83e9","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240314,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49819,"text":"ofr96402 - 1996 - Level II scour analysis for Bridge 4 (CRAFTH00040004) on Town Highway 4, crossing Whitney Brook, Craftsbury, Vermont","interactions":[],"lastModifiedDate":"2013-12-10T14:31:58","indexId":"ofr96402","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-402","title":"Level II scour analysis for Bridge 4 (CRAFTH00040004) on Town Highway 4, crossing Whitney Brook, Craftsbury, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCRAFTH00040004 on town highway 4 crossing Whitney Brook, Craftsbury, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the New England Upland secton of the New England physiographic province \nof north-central Vermont in the town of Craftsbury. The 13.3-mi2\n drainage area is in a \npredominantly rural and forested basin. In the vicinity of the study site, the banks have \ndense woody vegetation coverage.
\nIn the study area, Whitney Brook has an incised, sinuous channel with a slope of \napproximately 0.014 ft/ft, an average channel top width of 40 ft and an average channel \ndepth of 3 ft. The observed predominant channel bed material is cobble and boulder while \nresults from the pebble count provided a D50 of 78.5 mm or 0.258 ft. The geomorphic \nassessment at the time of the Level I and Level II site visit on June 7, 1995 indicated that the \nreach was stable.
\nThe town highway 4 crossing of Whitney Brook is a 41-ft-long, one-lane bridge consisting \nof one 39-foot span steel-beam and concrete superstructure (Vermont Agency of \nTransportation, written commun., August 3, 1994). The bridge is supported by slightly \nsloping, mortared stone block abutments with wingwalls. The channel is skewed \napproximately 20 degrees to the opening while the opening-skew-to-roadway is 20 degrees.
\nA scour hole 2 ft deeper than the mean thalweg depth was observed along the upstream \nright wingwall and right abutment during the Level I assessment. There were no scour \nprotection measures evident at the site. Additional details describing conditions at the site \nare included in the Level II Summary and Appendices D and E.
\nScour depths and rock riprap sizes were computed using the general guidelines described in \nHydraulic Engineering Circular 18 (Richardson and others, 1995).\nTotal scour at a highway crossing is comprised of three components: 1) long-term \ndegradation; 2) contraction scour (due to accelerated flow caused by reduction in flow area \nat a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). \nTotal scour is the sum of the three components. Equations are available to compute depths \nfor contraction and local scour and a summary of the computed scour results follow.
\nContraction scour for all modelled flows ranged from 0.7 to 1.7 feet. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 10.7 to \n15.3 feet. The worst-case abutment scour also occurred at the 500-year discharge. \nAdditional information on scour depths and depths to armoring are included in the section \ntitled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, \nare presented in tables 1 and 2. A cross-section of the scour computed at the bridge is \npresented in figure 8. Scour depths were calculated assuming an infinite depth of erosive \nmaterial and a homogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96402","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Boehmler, E.M., and Hammond, R.E., 1996, Level II scour analysis for Bridge 4 (CRAFTH00040004) on Town Highway 4, crossing Whitney Brook, Craftsbury, Vermont: U.S. Geological Survey Open-File Report 96-402, iv, 47 p., https://doi.org/10.3133/ofr96402.","productDescription":"iv, 47 p.","numberOfPages":"52","costCenters":[],"links":[{"id":178730,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":279347,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0402/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Craftsbury","otherGeospatial":"Whitney Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.5 ], [ -72.75,43.625 ], [ -72.625,43.625 ], [ -72.625,43.5 ], [ -72.75,43.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a622a","contributors":{"authors":[{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240316,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hammond, Robert E.","contributorId":61862,"corporation":false,"usgs":true,"family":"Hammond","given":"Robert","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":240315,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49820,"text":"ofr96403 - 1996 - Level II scour analysis for Bridge 15 (BRIDTH00220015) on Town Highway 22, crossing Dailey Hollow Branch, Bridgewater, Vermont","interactions":[],"lastModifiedDate":"2013-12-10T14:29:12","indexId":"ofr96403","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-403","title":"Level II scour analysis for Bridge 15 (BRIDTH00220015) on Town Highway 22, crossing Dailey Hollow Branch, Bridgewater, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nBRIDTH00220015 on town highway 22 crossing Dailey Hollow Branch, Bridgewater, \nVermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including \na quantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the Green Mountain section of the New England physiographic province of \ncentral Vermont in the town of Bridgewater. The 1.73-mi2\n drainage area is a predominantly \nrural and forested basin. In the vicinity of the study site, the left and right banks have dense \ntree cover. The upstream right bank of Dailey Hollow Branch is adjacent to town highway \n22.
\nIn the study area, Dailey Hollow Branch has a sinuous channel with a slope of \napproximately 0.035 ft/ft, an average channel top width of 30 ft and an average channel \ndepth of 4 ft. The predominant channel bed material is cobble with a median grain size \n(D50) of 108 mm (0.354 ft). The geomorphic assessment at the time of the Level I and Level \nII site visit on November 1 and 2, 1994, indicates that the reach is stable.
\nThe town highway 22 crossing of Dailey Hollow Branch is a 22-ft-long, one-lane bridge \nconsisting of one 22-ft. steel-beam span (Vermont Agency of Transportation, written \ncommunication, August 24, 1994). The bridge is supported by vertical, concrete abutments \nwith wingwalls. Type-1 stone fill (less than 12 inches diameter) protects the left abutment, \nbut it’s condition was reported as eroded. Type-2 stone fill (less than 36 inches diameter) \nprotects the upstream left wingwall; it’s condition was reported as slumping.The channel is \nskewed approximately 40 degrees to the opening while the opening-skew-to-roadway is 0 \ndegrees. Additional details describing conditions at the site are included in the Level II \nSummary and Appendices D and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1993). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.
\nContraction scour for all modelled flows ranged from 0.0 to 0.2 ft. with the worst-case \ncontraction scour occurring at the 500-year discharge. Abutment scour ranged from 4.2 to \n6.4 ft. The worst-case abutment scour also occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1993, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96403","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 15 (BRIDTH00220015) on Town Highway 22, crossing Dailey Hollow Branch, Bridgewater, Vermont: U.S. Geological Survey Open-File Report 96-403, iv, 48 p., https://doi.org/10.3133/ofr96403.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":178731,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":279346,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0403/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Bridgewater","otherGeospatial":"Dailey Hollow Branch","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.625 ], [ -72.75,43.75 ], [ -72.625,43.75 ], [ -72.625,43.625 ], [ -72.75,43.625 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a82ba","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240317,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49823,"text":"ofr96406 - 1996 - Level II scour analysis for Bridge 46 (CHELTH00680046) on Town Highway 68, crossing the First Branch of the White River, Chelsea, Vermont","interactions":[],"lastModifiedDate":"2013-12-10T14:21:02","indexId":"ofr96406","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-406","title":"Level II scour analysis for Bridge 46 (CHELTH00680046) on Town Highway 68, crossing the First Branch of the White River, Chelsea, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCHELTH00680046 on town highway 68 crossing the First Branch of the White River, \nChelsea, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, \nincluding a quantitative analysis of stream stability and scour (U.S. Department of \nTransportation, 1993). Results of a Level I scour investigation also are included in \nAppendix E of this report. A Level I investigation provides a qualitative geomorphic \ncharacterization of the study site. Information on the bridge, gleaned from Vermont Agency \nof Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II \nanalyses and is found in Appendix D.
\nThe site is in the Green Mountain section of the New England physiographic province of \ncentral Vermont in the town of Chelsea. The 58.2-mi2\n drainage area is in a predominantly \nrural and forested basin. In the vicinity of the study site, the banks have dense woody \nvegetation coverage.
\nIn the study area, the First Branch of the White River has a sinuous channel with a slope of \napproximately 0.0054 ft/ft, an average channel top width of 92 ft and an average channel \ndepth of 4 ft. The predominant channel bed material is gravel and cobble (D50 is 52.7 mm \nor 0.173 ft). The geomorphic assessment at the time of the Level I and Level II site visit on \nNovember 16, 1994, indicated that the reach was stable.
\nThe town highway 68 crossing of the First Branch of the White River is a 61-ft-long, onelane covered bridge with a 52-foot clear-span (Vermont Agency of Transportation, written \ncommun., August 26, 1994). The bridge is supported by vertical, stone abutments with a \nconcrete wingwall on the downstream right. The left abutment is laid-up stone supported by \nconcrete at the upstream and downstream ends of the laid-up stone abutment. The channel \nis skewed approximately 40 degrees to the opening while the opening-skew-to-roadway is \n15 degrees.
\nA scour hole 1.5 ft deeper than the mean thalweg depth was observed under the bridge \nduring the Level I assessment. The scour protection measures in place at the site were type-\n2 stone fill (less than 36 inches diameter) at the road approach embankments except the \ndownstream left embankment which had no protection. The upstream right road \nembankment, impacted by the channel bend, has an extensive covering of stone fill for \nerosion protection. Type-3 stone fill (less than 48 inches diameter) was noted along the \nright abutment. Additional details describing conditions at the site are included in the Level \nII Summary and Appendices\nD and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995).\nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 0.9 to 2.6 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 14.3 to \n24.0 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution. The left abutment sits atop a bedrock outcrop. The \nresults of the calculated scour depths will be limited by the bedrock.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96406","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ivanoff, M.A., and Song, D.L., 1996, Level II scour analysis for Bridge 46 (CHELTH00680046) on Town Highway 68, crossing the First Branch of the White River, Chelsea, Vermont: U.S. Geological Survey Open-File Report 96-406, iv, 50 p., https://doi.org/10.3133/ofr96406.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":178734,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96406.PNG"},{"id":279343,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0406/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Chelsea","otherGeospatial":"First Branch Of The White River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.5,43.875 ], [ -72.5,44.0 ], [ -72.375,44.0 ], [ -72.375,43.875 ], [ -72.5,43.875 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a60c8","contributors":{"authors":[{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240322,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Song, Donald L.","contributorId":107335,"corporation":false,"usgs":true,"family":"Song","given":"Donald","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240323,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49860,"text":"ofr96745 - 1996 - Level II scour analysis for Bridge 43 (HARDTH00CU0043) on Church Street, crossing the Lamoille River, Hardwick, Vermont","interactions":[],"lastModifiedDate":"2013-12-17T10:45:17","indexId":"ofr96745","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-745","title":"Level II scour analysis for Bridge 43 (HARDTH00CU0043) on Church Street, crossing the Lamoille River, Hardwick, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nHARDTH00CU0043 on Church Street crossing the Lamoille River, Hardwick, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nThe site is in the New England Upland section of the New England physiographic province \nin north-central Vermont. The 87.6-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover is best characterized as \nsuburban except for the downstream right surface cover which is pasture.\nIn the study area, the Lamoille River has an incised, straight channel with a slope of \napproximately 0.004 ft/ft, an average channel top width of 90 ft and an average channel \ndepth of 8 ft. The predominant channel bed materials are cobble and gravel with a median \ngrain size (DM50) of 99.5 mm (0.327 ft). The geomorphic assessment at the time of the Level \nI and Level II site visit on July 26, 1995, indicated that the reach was stable.\nThe Church Street crossing of the Lamoille River is a 100-ft-long, two-lane bridge \nconsisting of one 97-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, March 17, 1995). The bridge is supported by a vertical, stone abutment \nwith wingwalls on the left and a vertical concrete abutment with a stone spill-through slope \non the right. The channel is skewed approximately 5 degrees to the opening while the \nopening-skew-to-roadway is 0 degrees. Additional details describing conditions at the site \nare included in the Level II Summary and Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 0.0 to 0.8 ft. The worst-case \ncontraction scour occurred at the incipient-overtopping discharge. Abutment scour ranged \nfrom 6.2 to 10.9 ft at the left abutment with worst-case occurring at the incipientovertopping discharge. Abutment scour ranged from 8.5 to 12.3 ft at the right abutment with \nworst-case occurring at the 500-year discharge. Additional information on scour depths and \ndepths to armoring are included in the section titled “Scour Results”. Scoured-streambed \nelevations, based on the calculated scour depths, are presented in tables 1 and 2. A crosssection of the scour computed at the bridge is presented in figure 8. Scour depths were \ncalculated assuming an infinite depth of erosive material and a homogeneous particle-size \ndistribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96745","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 43 (HARDTH00CU0043) on Church Street, crossing the Lamoille River, Hardwick, Vermont: U.S. Geological Survey Open-File Report 96-745, iv, 52 p., https://doi.org/10.3133/ofr96745.","productDescription":"iv, 52 p.","numberOfPages":"57","costCenters":[],"links":[{"id":170313,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96745.PNG"},{"id":279576,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0745/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Hardwick","otherGeospatial":"Lamoille River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.5,44.375 ], [ -72.5,44.625 ], [ -72.25,44.625 ], [ -72.25,44.375 ], [ -72.5,44.375 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a61b9","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240376,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49859,"text":"ofr96744 - 1996 - Level II scour analysis for Bridge 38 (CONCTH00060038) on Town Highway 6, crossing the Moose River, Concord, Vermont","interactions":[],"lastModifiedDate":"2013-12-13T16:17:19","indexId":"ofr96744","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-744","title":"Level II scour analysis for Bridge 38 (CONCTH00060038) on Town Highway 6, crossing the Moose River, Concord, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCONCTH00060038 on Town Highway 6 crossing the Moose River, Concord, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nApproximately 85 percent of the drainage above the site is in the White Mountain section \nand 15 percent is in the New England Upland section of the New England physiographic \nprovince in northeastern Vermont. The 98.4-mi2\n drainage area is in a predominantly rural \nand forested basin. In the vicinity of the study site, the surface cover of the banks is \nprimarily forest and brush.\nIn the study area, the Moose River has an incised, sinuous channel with a slope of \napproximately 0.009 ft/ft, an average channel top width of 110 ft and an average channel \ndepth of 6 ft. The channel bed material ranged from gravel to boulder and had a median \ngrain size (D50) of 74.4 mm (0.244 ft). The geomorphic assessment at the time of the Level \nI and Level II site visit on August 17, 1995, indicated that the reach was stable.\nThe Town Highway 6 crossing of the Moose River is a 59-ft-long, two-lane bridge \nconsisting of one 55-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, March 24, 1995). The bridge is supported by a vertical, laid-up stone \nabutment with wingwalls on the left and a vertical, concrete abutment with wingwalls on \nthe right. The channel is skewed approximately 10 degrees to the opening while the \nopening-skew-to-roadway is 0 degrees.\nThe footing of the left abutment is exposed as much as 2.8 feet. The footing of the right \nabutment is undermined vertically by as much as 0.3 feet. Type-2 stone-fill (less than 36 \ninches diameter) protection can be found along the left abutment. Type-3 stone-fill (less \nthan 48 inches diameter) protection can be found along the right abutment. Additional \ndetails describing conditions at the site are included in the Level II Summary and \nAppendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 0.1 to 3.1 ft. The worst-case \ncontraction scour occurred at the incipient-overtopping discharge. Abutment scour at the \nleft abutment ranged from 10.4 to 12.5 ft with the worst-case occurring at the 500-year \ndischarge. Abutment scour at the right abutment ranged from 25.3 to \n27.3 ft with the worst-case occurring at the incipient-overtopping discharge. The worst-case \ntotal scour also occurred at the incipient-overtopping discharge. The incipient-overtopping \ndischarge was in between the 100- and 500-year discharges. Additional information on \nscour depths and depths to armoring are included in the section titled “Scour Results”. \nScoured-streambed elevations, based on the calculated scour depths, are presented in tables \n1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour \ndepths were calculated assuming an infinite depth of erosive material and a homogeneous \nparticle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96744","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 38 (CONCTH00060038) on Town Highway 6, crossing the Moose River, Concord, Vermont: U.S. Geological Survey Open-File Report 96-744, iv, 50 p., https://doi.org/10.3133/ofr96744.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":170312,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96744.PNG"},{"id":279575,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0744/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Concord","otherGeospatial":"Moose River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ 72.0,44.375 ], [ 72.0,44.5 ], [ 71.875,44.5 ], [ 71.875,44.375 ], [ 72.0,44.375 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a6231","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240375,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49858,"text":"ofr96743 - 1996 - Level II scour analysis for Bridge 5 (CHELTH00030005) on Town Highway 3, crossing Jenkins Brook, Chelsea, Vermont","interactions":[],"lastModifiedDate":"2013-12-13T16:03:44","indexId":"ofr96743","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-743","title":"Level II scour analysis for Bridge 5 (CHELTH00030005) on Town Highway 3, crossing Jenkins Brook, Chelsea, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCHELTH00030005 on town highway 3 crossing Jenkins Brook, Chelsea, Vermont (figures \n1–8). A Level II study is a basic engineering analysis of the site, including a quantitative \nanalysis of stream stability and scour (U.S. Department of Transportation, 1993). Results \nof a Level I scour investigation also are included in Appendix E of this report. A Level I \nstudy provides a qualitative geomorphic characterization of the study site. Information on \nthe bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled \nprior to conducting Level I and Level II analyses and is found in Appendix D.\nThe site is in the New England Upland section of the New England physiographic province \nof central Vermont in the town of Chelsea. The 6.97-mi2\n drainage area is in a \npredominantly rural and forested basin. In the vicinity of the study site, the surface cover is \nforest.\nIn the study area, Jenkins Brook has an incised, sinuous channel with a slope of \napproximately 0.04 ft/ft, an average channel top width of 48 ft and an average channel \ndepth of 3 ft. The predominant channel bed material is cobble with a median grain size \n(D50) of 154 mm (0.506 ft). The geomorphic assessment at the time of the Level I and Level \nII site visit on November 17, 1994, indicated that the reach was stable.\nThe town highway 3 crossing of Jenkins Brook is a 23-ft-long bridge consisting of one 20-\nfoot concrete span (Vermont Agency of Transportation, written communication, August 25, \n1994). The bridge is supported by vertical, concrete abutments with wingwalls. The \nupstream wingwalls are protected by type-3 stone fill (less than 48 inches diameter) and the \ndownstream wingwalls have type-2 stone fill (less than 36 inches diameter). The footings of \nboth abutments are exposed. The channel is skewed approximately 25 degrees to the \nopening while the opening-skew-to-roadway is 15 degrees. Additional details describing \nconditions at the site are included in the Level II Summary and Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows was 0.0 ft. Abutment scour ranged from 7.6 to \n12.4 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution.\n It is generally accepted that the Froehlich equation (abutment scour) gives \n“excessively conservative estimates of scour depths” (Richardson and others, 1995, \np. 47). Usually, computed scour depths are evaluated in combination with other \ninformation including (but not limited to) historical performance during flood \nevents, the geomorphic stability assessment, existing scour protection measures, \nand the results of the hydraulic analyses. Therefore, scour depths adopted by \nVTAOT may differ from the computed values documented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr96743","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ivanoff, M.A., 1996, Level II scour analysis for Bridge 5 (CHELTH00030005) on Town Highway 3, crossing Jenkins Brook, Chelsea, Vermont: U.S. Geological Survey Open-File Report 96-743, iv, 49 p., https://doi.org/10.3133/ofr96743.","productDescription":"iv, 49 p.","numberOfPages":"54","costCenters":[],"links":[{"id":162286,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96743.PNG"},{"id":279574,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0743/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Chelsea","otherGeospatial":"Jenkins Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.5,43.875 ], [ -72.5,44.0 ], [ -72.375,44.0 ], [ -72.375,43.875 ], [ -72.5,43.875 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a5f52","contributors":{"authors":[{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240374,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49785,"text":"ofr96195 - 1996 - Level II scour analysis for Bridge 27 (BRIDTH00490027) on Town Highway 049, crossing Broad Brook, Bridgewater, Vermont","interactions":[],"lastModifiedDate":"2013-12-06T15:01:48","indexId":"ofr96195","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-195","title":"Level II scour analysis for Bridge 27 (BRIDTH00490027) on Town Highway 049, crossing Broad Brook, Bridgewater, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nBRIDTH00490027 on town highway 49 crossing Broad Brook, Bridgewater, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). A Level I study is included in Appendix E of this report. A Level I study provides \na qualitative geomorphic characterization of the study site. Information on the bridge \navailable from VTAOT files was compiled prior to conducting Level I and Level II \nanalyses and can be found in Appendix D.\nThe site is in the Green Mountain physiographic province of central Vermont in the town of \nBridgewater. The 13.9-mi2 drainage area is in a predominantly rural and forested basin. In \nthe vicinity of the study site, the left and right banks are pasture with moderate tree cover on \nthe immediate banks. Upstream of bridge 27, a gravel road runs parallel to the left bank.\nIn the study area, the Broad Brook has an incised channel with a slope of approximately \n0.007 ft/ft, an average channel top width of 54 ft and an average channel depth of 4 ft. The \npredominant channel bed materials are gravel and cobble with a D50 (median diameter) \nof \n77.9 mm or 0.256 ft. The geomorphic assessment at the time of the Level I and Level II site \nvisit on November 9, 1994, indicated that the reach was stable.\nThe town highway 49 crossing of the Broad Brook is a 32-ft-long, one-lane bridge \nconsisting of one 31-ft steel-beam span (Vermont Agency of Transportation, written \ncommun., August 24, 1994). The bridge is supported by vertical, concrete abutments with \nwingwalls. The left abutment is noted as settled due to previous undermining. Type-2 (less \nthan 3 ft diameter) stone fill protects the upstream left and right wingwalls, the downstream \nright wingwall, the right abutment, the upstream right road embankment, and the \ndownstream left and right road embankments. Type-3 (less than 4 ft diameter) stone fill \nprotects the downstream left wingwall, but it’s condition was reported as slumping. The \nchannel is skewed approximately 10 degrees to the opening; the opening-skew-to-roadway \nis also 10 degrees. Additional details describing conditions at the site are included in the \nLevel II Summary and Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1993). Scour depths were \ncalculated assuming an infinite depth of erosive material and a homogeneous particle-size \ndistribution. The scour analysis results are presented in tables 1 and 2 and a graph of the \nscour depths is presented in figure 8.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96195","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 27 (BRIDTH00490027) on Town Highway 049, crossing Broad Brook, Bridgewater, Vermont: U.S. Geological Survey Open-File Report 96-195, iv, 30 p., https://doi.org/10.3133/ofr96195.","productDescription":"iv, 30 p.","numberOfPages":"35","costCenters":[],"links":[{"id":178610,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96195.png"},{"id":279410,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0195/report.pdf"}],"country":"United States","state":"Vermont","city":"Bridgewater","otherGeospatial":"Broad Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.758005,43.558839 ], [ -72.758005,43.694051 ], [ -72.577733,43.694051 ], [ -72.577733,43.558839 ], [ -72.758005,43.558839 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a7fcd","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240256,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49851,"text":"ofr96641 - 1996 - Level II scour analysis for Bridge 36 (RANDTH00480036) on Town Highway 48, crossing Snows Brook, Randolph, Vermont","interactions":[],"lastModifiedDate":"2013-12-05T14:28:19","indexId":"ofr96641","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-641","title":"Level II scour analysis for Bridge 36 (RANDTH00480036) on Town Highway 48, crossing Snows Brook, Randolph, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nRANDTH00480036 on town highway 48 crossing Snows Brook, Randolph, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nThe site is in the Green Mountain section of the New England physiographic province of \ncentral Vermont. The 3.72-mi2\n drainage area is in a predominantly rural and forested basin. \nIn the vicinity of the study site, the surface cover is forest.\nIn the study area, Snows Brook has an incised, sinuous channel with a slope of \napproximately 0.03 ft/ft, an average channel top width of 27 ft and an average channel \ndepth of 3 ft. The predominant channel bed material is cobble with a median grain size \n(D50) of 72.7 mm (0.238 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on August 9, 1994, indicated that the reach was laterally unstable.\nThe town highway 48 crossing of Snows Brook is a 32-ft-long, two-lane bridge consisting \nof one 28-foot concrete span (Vermont Agency of Transportation, written communication, \nJuly 29, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The \nchannel is skewed approximately 40 degrees to the opening while the opening-skew-toroadway is 45 degrees. Additional details describing conditions at the site are included in \nthe Level II Summary and Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 0.0 to 0.8 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 6.1 to \n11.6 ft. The worst-case abutment scour occurred at the incipient-overtopping discharge, \nwhich was 50 cfs lower than the 500-year discharge. Additional information on scour \ndepths and depths to armoring are included in the section titled “Scour Results”. Scouredstreambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. \nA cross-section of the scour computed at the bridge is presented in figure 8. Scour depths \nwere calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. \n It is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96641","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 36 (RANDTH00480036) on Town Highway 48, crossing Snows Brook, Randolph, Vermont: U.S. Geological Survey Open-File Report 96-641, iv, 49 p., https://doi.org/10.3133/ofr96641.","productDescription":"iv, 49 p.","numberOfPages":"54","costCenters":[],"links":[{"id":162730,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96641.PNG"},{"id":279274,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0641/report.pdf"}],"country":"United States","state":"Vermont","city":"Randolph","otherGeospatial":"Snows Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.703521,43.873348 ], [ -72.703521,44.000618 ], [ -72.509922,44.000618 ], [ -72.509922,43.873348 ], [ -72.703521,43.873348 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a63fa","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240364,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49850,"text":"ofr96640 - 1996 - Level II scour analysis for Bridge 1 (CANATH00010001) on Town Highway 1, crossing Halls Stream, Canaan, Vermont","interactions":[],"lastModifiedDate":"2013-12-05T14:19:55","indexId":"ofr96640","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-640","title":"Level II scour analysis for Bridge 1 (CANATH00010001) on Town Highway 1, crossing Halls Stream, Canaan, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCANATH00010001 on town highway 1 crossing Halls Stream, Canaan, Vermont (figures \n1–8). A Level II study is a basic engineering analysis of the site, including a quantitative \nanalysis of stream stability and scour (U.S. Department of Transportation, 1993). A Level I \nstudy is included in Appendix E of this report. A Level I study provides a qualitative \ngeomorphic characterization of the study site. Information on the bridge, gleaned from \nVermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level \nI and Level II analyses and can be found in Appendix D.\nThe site is in the White Mountain section of the New England physiographic province of \nnortheastern Vermont in the town of Canaan. The 89.5-mi2\n drainage area is in a \npredominantly rural and forested basin. In the vicinity of the study site, the banks have tree, \nshrub and brush, and grass vegetation coverage.\nIn the study area, Halls Stream has a sinuous channel with a slope of approx-imately 0.0012 \nft/ft, an average channel top width of 109 ft and an average channel depth of 4 ft. The \npredominant channel bed materials are sand and gravel (D50 is 5.03 mm or 0.0165 ft). The \ngeomorphic assessment at the time of the Level I and Level II site visit on October 27, \n1994, indicated that the reach was laterally unstable. The lateral instability was evident due \nto a wide point-bar and cut-banks with undermining of bank material, slumping, fallen bank \nvegetation evident in the upstream channel. \nThe town highway 1 crossing of Halls Stream is a 99-ft-long, two-lane bridge consisting of \none 33-foot and two 31-foot concrete T-beam spans (Vermont Agency of Transportation, \nwritten communication, August 5, 1994). The bridge is supported by vertical, concrete \nabutments with spill-through embankments in front of each abutment wall. The channel is \nskewed approximately 10 degrees to the opening while the opening-skew-to-roadway is \nzero degrees. \nThere are two piers in the channel at this site. Field notes and the channel survey at the \nbridge indicate that the streambed elevation is higher on the downstream right sides of each \npier and lower on the downstream left sides. This asymmetrical streambed condition\nsuggests a flow attack angle may influence scour on each pier. Furthermore, field \nobservations suggest that the flow attack angle is higher for the right pier (pier 2) than the \nleft pier (pier 1).\nThe scour protection measures at the site were type-2 stone fill (less than 36 inches \ndiameter) on both upstream banks and both downstream road embankments. Type-3 stone \nfill (less than 48 inches diameter) was found on the spill-through slopes of each abutment \nand both downstream banks. The stone fill protection on the spill-through embankment of \nthe right abutment was noted as slumped with some of the fill material evident in the \nchannel immediately downstream of the bridge. Additional details describing conditions at \nthe site are included in the Level II Summary and Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 8.0 to 8.8 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 8.9 to \n17.3 ft. The worst-case abutment scour occurred at the 500-year discharge. For the two \npiers, scour ranged from 11.1 to 15.8. The worst-case pier scour occurred for pier2 at the \nincipient overtopping discharge. Additional information on scour depths and depths to \narmoring are included in the section titled “Scour Results”. Scoured-streambed elevations, \nbased on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the \nscour computed at the bridge is presented in figure 8. Scour depths were calculated \nassuming an infinite depth of erosive material and a homogeneous particle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96640","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Boehmler, E.M., 1996, Level II scour analysis for Bridge 1 (CANATH00010001) on Town Highway 1, crossing Halls Stream, Canaan, Vermont: U.S. Geological Survey Open-File Report 96-640, iv, 51 p., https://doi.org/10.3133/ofr96640.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":162729,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96640.PNG"},{"id":279276,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0640/report.pdf"}],"country":"United States","state":"Vermont","city":"Canaan","otherGeospatial":"Halls Stream","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -71.705447,44.906853 ], [ -71.705447,45.013639 ], [ -71.465039,45.013639 ], [ -71.465039,44.906853 ], [ -71.705447,44.906853 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a8490","contributors":{"authors":[{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240363,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49849,"text":"ofr96639 - 1996 - Level II scour analysis for Bridge 49 (WODSTH00990049) on Town Highway 99, crossing Gulf Brook, Woodstock, Vermont","interactions":[],"lastModifiedDate":"2013-12-05T14:25:44","indexId":"ofr96639","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-639","title":"Level II scour analysis for Bridge 49 (WODSTH00990049) on Town Highway 99, crossing Gulf Brook, Woodstock, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nWODSTH00990049 on Town Highway 99 crossing the Gulf Brook, Woodstock, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nThe site is in the New England Upland section of the New England physiographic province \nin east-central Vermont. The 16.8-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the primary surface cover is pasture except for \nupstream right of the bridge which is cover by trees and brush. The immediate banks \nthroughout the reach have scattered woody vegetation.\nIn the study area, the Gulf Brook has an incised, sinuous channel with a slope of \napproximately 0.01 ft/ft, an average channel top width of 91 ft and an average channel \ndepth of 6 ft. The channel bed materials range from sand to cobble with a median grain size \n(D50) of 85.3 mm (0.280 ft). The geomorphic assessment at the time of the Level I site visits \non September 15, 1994 and December 14, 1994, indicated that the reach was stable.\nThe Town Highway 99 crossing of the Gulf Brook is a 56-ft-long, one-lane bridge \nconsisting of one 55-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, April 4, 1995). The bridge is supported by vertical, concrete abutments \nwith a spill-through slope constructed of large quarried stone. The channel is skewed \napproximately 20 degrees to the opening while the opening-skew-to-roadway is 0 degrees. \nErosion at the right abutment has undermined the toe of the spill-through slope by nearly a \nfoot. Material has been removed from under the stone spill-through slope so that 0.5 feet of \nhorizontal penetration was possible at the time of the visits. Additional details describing \nconditions at the site are included in the Level II Summary and Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 0.0 to 0.9 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour at the left abutment \nranged from 3.1 to 10.3 ft. with the worst-case occurring at the 500-year discharge. \nAbutment scour at the right abutment ranged from 6.4 to 10.4 ft. with the worst-case \noccurring at the 100-year discharge.Additional information on scour depths and depths to \narmoring are included in the section titled “Scour Results”. Scoured-streambed elevations, \nbased on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the \nscour computed at the bridge is presented in figure 8. Scour depths were calculated \nassuming an infinite depth of erosive material and a homogeneous particle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96639","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., and Hammond, R.E., 1996, Level II scour analysis for Bridge 49 (WODSTH00990049) on Town Highway 99, crossing Gulf Brook, Woodstock, Vermont: U.S. Geological Survey Open-File Report 96-639, iv, 50 p., https://doi.org/10.3133/ofr96639.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":162728,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96639.PNG"},{"id":279277,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0639/report.pdf"}],"country":"United States","state":"Vermont","city":"Woodstock","otherGeospatial":"Gulf Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.637941,43.533341 ], [ -72.637941,43.661214 ], [ -72.46644,43.661214 ], [ -72.46644,43.533341 ], [ -72.637941,43.533341 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a610d","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240361,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hammond, Robert E.","contributorId":61862,"corporation":false,"usgs":true,"family":"Hammond","given":"Robert","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":240362,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49848,"text":"ofr96638 - 1996 - Level II scour analysis for Bridge 23 (HARDTH00530023) on Town Highway 53, crossing Haynesville Brook, Hardwick, Vermont","interactions":[],"lastModifiedDate":"2013-12-05T14:34:44","indexId":"ofr96638","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-638","title":"Level II scour analysis for Bridge 23 (HARDTH00530023) on Town Highway 53, crossing Haynesville Brook, Hardwick, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nHARDTH00530023 on Town Highway 53 crossing Haynesville Brook, Hardwick, \nVermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including \na quantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nThe site is in the New England Upland section of the New England physiographic province \nin north-central Vermont. The 14.2-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the predominate surface cover consists of \nfield grasses except for the upstream left bank with is brush covered.\nIn the study area, Haynesville Brook has a sinuous channel with a slope of approximately \n0.004 ft/ft, an average channel top width of 39 ft and an average channel depth of 2 ft. \nStream-bed material at the site ranged from silt to gravel with a median grain size (D50) of \n49.9 mm (0.164ft). The geomorphic assessment at the time of the Level I and Level II site \nvisit on July 27, 1995, indicated that the reach was laterally unstable. Channel scour in both \nthe upstream and downstream reaches as well as irregular point bars and cut banks and \nupstream anabranching led to this assessment. \nThe Town Highway 53 crossing of Haynesville Brook is a 33-ft-long, one-lane bridge \nconsisting of one 26-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, March 24, 1994). The bridge is supported by vertical, concrete abutments \nwith no wingwalls. The concrete may be facing over the original stone abutments. Sheet \npiling has been driven around the base of each abutment and is filled with concrete. The \nchannel is skewed approximately 10 degrees to the opening; the opening-skew-to-roadway \nis also 10 degrees. Additional details describing conditions at the site are included in the \nLevel II Summary and Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 0.0 to 2.0 ft. The worst-case \ncontraction scour occurred at the 100-year discharge. Abutment scour ranged from 7.0 to \n12.9 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96638","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 23 (HARDTH00530023) on Town Highway 53, crossing Haynesville Brook, Hardwick, Vermont: U.S. Geological Survey Open-File Report 96-638, iv, 50 p., https://doi.org/10.3133/ofr96638.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":162727,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96638.PNG"},{"id":279278,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0638/report.pdf"}],"country":"United States","state":"Vermont","city":"Hardwick","otherGeospatial":"Haynesville Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.434315,44.462456 ], [ -72.434315,44.584125 ], [ -72.262965,44.584125 ], [ -72.262965,44.462456 ], [ -72.434315,44.462456 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a80f9","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240360,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49847,"text":"ofr96637 - 1996 - Level II scour analysis for Bridge 24 (HARDTH00490024) on Town Highway 49, crossing Nichols Brook at Mackville Pond Outlet, Hardwick, Vermont","interactions":[],"lastModifiedDate":"2013-12-05T14:44:37","indexId":"ofr96637","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-637","title":"Level II scour analysis for Bridge 24 (HARDTH00490024) on Town Highway 49, crossing Nichols Brook at Mackville Pond Outlet, Hardwick, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nHARDTH00490024 on Town Highway 49 crossing Nichols Brook at Mackville Pond \nOutlet, Hardwick, Vermont (figures 1–8). A Level II study is a basic engineering analysis of \nthe site, including a quantitative analysis of stream stability and scour (U.S. Department of \nTransportation, 1993). Results of a Level I scour investigation also are included in \nAppendix E of this report. A Level I investigation provides a qualitative geomorphic \ncharacterization of the study site. Information on the bridge, gleaned from Vermont Agency \nof Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II \nanalyses and is found in Appendix D.\nThe site is in the New England Upland section of the New England physiographic province \nin north-central Vermont. The 10.7-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover is best described as \nsuburban with residences, lawns, trees and roadways.\nThere is a dam 54 feet downstream of the bridge which controls Mackville Pond upstream \nof the bridge. The vertical drop over the dam is 15 feet. Immediately upstream of the bridge \nthe width of the waterway is 146 feet. The predominant channel bed material is sand with a \nmedian grain size (D50) of 0.576 mm (0.00189 ft). The geomorphic assessment at the time \nof the Level I and Level II site visit on July 25, 1995, indicated that the reach was stable.\nThe Town Highway 49 crossing of Nichols Brook at Mackville Pond Outlet is a 42-ft-long, \ntwo-lane bridge consisting of one 38-foot steel-beam span (Vermont Agency of \nTransportation, written communication, April 3, 1995). The bridge is supported by vertical, \nconcrete abutments with wingwalls on the downstream end of the left abutment and \nupstream and downstream ends of the right abutment. The channel is not skewed to the \nopening, but the opening-skew-to-roadway is 5 degrees.\nScour protection measures at the site include type-3 stone fill (less than 48 inches diameter) \non the upstream side of the left roadway embankment and at the upstream end of the left \nabutment. Type-2 stone fill (less than 36 inches diameter) was on the upstream right \nroadway embankment. Additional details describing conditions at the site are included in \nthe Level II Summary and Appendices \nD and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 4.7 to 21.0 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour at the left abutment \nranged from 13.3 to 15.8 ft. with the worst-case occurring at the 500-year discharge. \nAbutment scour at the right abutment ranged from 8.1 to 9.8 ft. with the worst-case \noccurring at the incipient roadway-overtopping discharge. Additional information on scour \ndepths and depths to armoring are included in the section titled “Scour Results”. Scouredstreambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. \nA cross-section of the scour computed at the bridge is presented in figure 8. Scour depths \nwere calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96637","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 24 (HARDTH00490024) on Town Highway 49, crossing Nichols Brook at Mackville Pond Outlet, Hardwick, Vermont: U.S. Geological Survey Open-File Report 96-637, iv, 51 p., https://doi.org/10.3133/ofr96637.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":162647,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96637.PNG"},{"id":279279,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0637/report.pdf"}],"country":"United States","state":"Vermont","city":"Hardwick","otherGeospatial":"Mackville Pond Outlet","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.434315,44.462456 ], [ -72.434315,44.584125 ], [ -72.262965,44.584125 ], [ -72.262965,44.462456 ], [ -72.434315,44.462456 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a80c3","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240359,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49846,"text":"ofr96636 - 1996 - Level II scour analysis for Bridge 25 (CLARTH00100025) on Town Highway 10, crossing the Clarendon River, Clarendon, Vermont","interactions":[],"lastModifiedDate":"2013-12-05T14:51:26","indexId":"ofr96636","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-636","title":"Level II scour analysis for Bridge 25 (CLARTH00100025) on Town Highway 10, crossing the Clarendon River, Clarendon, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCLARTH00100025 on town highway 10 crossing the Clarendon River, Clarendon, \nVermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including \na quantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Resultsof a Level I scour investigation also are included in Appendix E of this \nreport. A Level I study provides a qualitative geomorphic characterization of the study site. \nInformation on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) \nfiles, was compiled prior to conducting Level I and Level II analyses and is found in \nAppendix D.\nThe site is in the Taconic Section of the New England physiographic province in westcentral Vermont. The 19.3-mi2\n drainage area is in a predominantly rural basin. In the \nvicinity of the study site, the left and right banks are covered by pasture and (or) fields. The \nright bank of Clarendon River is eroded due to stream-flow attack immediately upstream of \nthe bridge.\nIn the study area, the Clarendon River has a sinuous channel with a slope of approximately \n0.007 ft/ft, an average channel top width of 44 ft and an average channel depth of 3 ft. There \nare large meanders approximately 100 feet upstream and downstream of the bridge. The \npredominant channel bed materials are gravel and cobbles with a median grain size (D50) of \n42.4 mm (0.139 ft). The geomorphic assessment at the time of the Level I and Level II site \nvisit on April 27, 1995, indicated that the reach was laterally unstable.\nThe town highway 10 crossing of the Clarendon River was a 27-ft-long, two-lane bridge \nconsisting of one 24-foot steel stringer with a timber deck (Vermont Agency of \nTransportation, written communication, March 13, 1995). The deck was removed at the \ntime of the survey but the analysis was done as if the old deck was in place. The bridge is \nsupported on the left by a vertical stone abutment and on the right by a vertical, concrete \nabutment with an upstream wingwall. The channel is skewed approximately 10 degrees to \nthe opening while the opening-skew-to-roadway is 0 degrees. \nA scour hole 3 ft deeper than the mean thalweg depth was observed along the right bank \nextending from 24 to 60 feet upstream of the bridge. No scour prevention measures were \nobserved at this site at the time of the site visit. Additional details describing conditions at \nthe site are included in the Level II Summary and Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 0.0 to 0.8 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 5.7 to \n10.6 ft. The worst-case abutment scour also occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution. \n It is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96636","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ayotte, J., 1996, Level II scour analysis for Bridge 25 (CLARTH00100025) on Town Highway 10, crossing the Clarendon River, Clarendon, Vermont: U.S. Geological Survey Open-File Report 96-636, iv, 50 p., https://doi.org/10.3133/ofr96636.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":162646,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96636.PNG"},{"id":279280,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0636/report.pdf"}],"country":"United States","state":"Vermont","city":"Clarendon","otherGeospatial":"Clarendon River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.050832,43.484502 ], [ -73.050832,43.574704 ], [ -72.92847,43.574704 ], [ -72.92847,43.484502 ], [ -73.050832,43.484502 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a8086","contributors":{"authors":[{"text":"Ayotte, Joseph D. jayotte@usgs.gov","contributorId":1802,"corporation":false,"usgs":true,"family":"Ayotte","given":"Joseph D.","email":"jayotte@usgs.gov","affiliations":[{"id":466,"text":"New England Water Science Center","active":true,"usgs":true}],"preferred":false,"id":240358,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49845,"text":"ofr96635 - 1996 - Level II scour analysis for Bridge 6 (RICHTH00030006) on Town Highway 3, crossing an unnamed tributary to the Missisquoi River, Richford, Vermont","interactions":[],"lastModifiedDate":"2013-12-05T14:57:41","indexId":"ofr96635","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-635","title":"Level II scour analysis for Bridge 6 (RICHTH00030006) on Town Highway 3, crossing an unnamed tributary to the Missisquoi River, Richford, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nRICHTH00030006 on Town Highway 3 crossing an unnamed tributary to the Missisquoi \nRiver, Richford, Vermont (figures 1–8). A Level II study is a basic engineering analysis of \nthe site, including a quantitative analysis of stream stability and scour (U.S. Department of \nTransportation, 1993). Results of a Level I scour investigation also are included in \nAppendix E of this report. A Level I investigation provides a qualitative geomorphic \ncharacterization of the study site. Information on the bridge, gleaned from Vermont Agency \nof Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II \nanalyses and is found in Appendix D.\nThe site is in the Green Mountain section of the New England physiographic province of \nnorthern Vermont. The 4.5-mi2\n drainage area is in a predominantly rural basin. In the \nvicinity of the study site, the surface cover is pasture upstream and downstream of the \nbridge.\nIn the study area, the unnamed tributary to the Missisquoi River is a sinuous channel with a \nslope of approximately 0.008 ft/ft, an average channel top width of 39 ft and an average \nchannel depth of 2 ft. The channel slope was obtained from a topographic map (USGS, \n1986). The predominant channel bed material is gravel with a median grain size (D50) of \n26.2 mm (0.0861 ft). The geomorphic assessment at the time of the Level I and Level II site \nvisit on June 28, 1995, indicated that the reach was stable.\nThe Town Highway 3 crossing of an unnamed tributary to the Missisquoi River is a 26-ftlong, two-lane bridge consisting of one 24-foot concrete T-beam span (Vermont Agency of \nTransportation, written communication, March 9, 1995). The bridge is supported by \nvertical, concrete abutments with wingwalls. The channel is skewed approximately 40 \ndegrees to the opening while the opening-skew-to-roadway is 0.0 degrees. \nThe only scour protection measures at the site were type-2 stone fill (less than 36 inches \ndiameter) along the upstream right wingwall and at the upstream end of the right abutment. \nAdditional details describing conditions at the site are included in the Level II Summary \nand Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 1.7 to 1.8 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Scour at the left abutment ranged \nfrom 7.6 to 12.6 ft with the worst case occurring at the 100-year event. Scour at the right \nabutment ranged from 1.6 to 5.6 ft with the worst case occurring at the 500-year event. \nAdditional information on scour depths and depths to armoring are included in the section \ntitled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, \nare presented in tables 1 and 2. A cross-section of the scour computed at the bridge is \npresented in figure 8. Scour depths were calculated assuming an infinite depth of erosive \nmaterial and a homogeneous particle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96635","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Flynn, R.H., and Song, D.L., 1996, Level II scour analysis for Bridge 6 (RICHTH00030006) on Town Highway 3, crossing an unnamed tributary to the Missisquoi River, Richford, Vermont: U.S. Geological Survey Open-File Report 96-635, iv, 48 p., https://doi.org/10.3133/ofr96635.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":162645,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96635.PNG"},{"id":279281,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0635/report.pdf"}],"country":"United States","state":"Vermont","city":"Richford","otherGeospatial":"Missisquoi River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.702647,44.921965 ], [ -72.702647,45.015684 ], [ -72.535709,45.015684 ], [ -72.535709,44.921965 ], [ -72.702647,44.921965 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a5c28","contributors":{"authors":[{"text":"Flynn, Robert H. rflynn@usgs.gov","contributorId":2137,"corporation":false,"usgs":true,"family":"Flynn","given":"Robert","email":"rflynn@usgs.gov","middleInitial":"H.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240356,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Song, Donald L.","contributorId":107335,"corporation":false,"usgs":true,"family":"Song","given":"Donald","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240357,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49844,"text":"ofr96587 - 1996 - Level II scour analysis for Bridge 38 (RANDTH00640038) on Town Highway 64, crossing the Second Branch of the White River, Randolph, Vermont","interactions":[],"lastModifiedDate":"2013-12-05T15:04:29","indexId":"ofr96587","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-587","title":"Level II scour analysis for Bridge 38 (RANDTH00640038) on Town Highway 64, crossing the Second Branch of the White River, Randolph, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nRANDTH00640038 on town highway 64 crossing the Second Branch of the White River, \nRandolph, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the \nsite, including a quantitative analysis of stream stability and scour (U.S. Department of \nTransportation, 1993). Results of a Level I scour investigation also are included in \nAppendix E of this report. A Level I investigation provides a qualitative geomorphic \ncharacterization of the study site. Information on the bridge, gleaned from Vermont Agency \nof Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II \nanalyses and is found in Appendix D.\nThe site is in the Green Mountain section of the New England physiographic province of \ncentral Vermont. The 46.5-mi2\n drainage area is in a predominantly rural and forested basin. \nIn the vicinity of the study site, the The upstream left bank is forested, the upstream right \nbank is covered primarily by brush, the surface cover is pasture on the downstream left and \nrow crops on the downstream right. \nIn the study area, the Second Branch of the White River has an incised, sinuous channel \nwith a slope of approximately 0.0015 ft/ft, an average channel top width of 71 ft and an \naverage channel depth of 8 ft. The predominant channel bed material is gravel with a \nmedian grain size (D50) of 32.0 mm (0.105 ft). The geomorphic assessment at the time of \nthe Level I site visits on August 10, 1994 and December 5, 1994 indicated that the reach \nwas laterally unstable.\nThe town highway 64 crossing of the Second Branch of the White Riveris a 43-ft-long, \none-lane covered bridge consisting of one 35-foot steel-beam span (Vermont Agency of \nTransportation, written communication, August 1, 1994). The bridge is supported by \nvertical, stone abutments with upstream wingwalls. The channel bends sharply at it’s \napproach to the bridge, however, at the bridge face, the channel is skewed approximately 0 \ndegrees to the opening. The opening-skew-to-roadway is also 0 degrees.\nA scour hole 2 ft deeper than the mean thalweg depth was observed upstream of the bridge \nalong the outside of the channel bend. Other scour problems at this site included \nundermining of the right abutment at it’s upstream and downstream ends. Additional details \ndescribing conditions at the site are included in the Level II Summary and Appendices D \nand E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 1.7 to 2.6 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 7.2 to \n24.2 ft. The worst-case abutment scour also occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96587","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1996, Level II scour analysis for Bridge 38 (RANDTH00640038) on Town Highway 64, crossing the Second Branch of the White River, Randolph, Vermont: U.S. Geological Survey Open-File Report 96-587, iv, 51 p., https://doi.org/10.3133/ofr96587.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":162644,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96587.PNG"},{"id":279282,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0587/report.pdf"}],"country":"United States","state":"Vermont","city":"Randolph","otherGeospatial":"White River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.703521,43.873348 ], [ -72.703521,44.000618 ], [ -72.509922,44.000618 ], [ -72.509922,43.873348 ], [ -72.703521,43.873348 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a628e","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240355,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49843,"text":"ofr96586 - 1996 - Level II scour analysis for Bridge 94 (FERDVT01050094) on State Route 105, crossing the Nulhegan River, Ferdinand, Vermont","interactions":[],"lastModifiedDate":"2013-12-05T15:09:37","indexId":"ofr96586","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1996","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"96-586","title":"Level II scour analysis for Bridge 94 (FERDVT01050094) on State Route 105, crossing the Nulhegan River, Ferdinand, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nFERDVT01050094 on State Route 105 crossing the Nulhegan River, Ferdinand, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nThe site is in the White Mountain section of the New England physiographic province in \nnortheastern Vermont. The 38.4-mi2\n drainage area is in a predominantly rural and forested\nbasin. In the vicinity of the study site, the surface cover is grass and brush with wetlands \nimmediately adjacent to the stream channel.\nIn the study area, the Nulhegan River has a meandering channel with a slope of \napproximately 0.002 ft/ft, an average channel top width of 60 ft and an average channel \ndepth of 6 ft. The predominant channel bed material is sand with a median grain size (D50) \nof 0.465 mm (0.00153 ft). The geomorphic assessment at the time of the Level I and Level \nII site visit on July 5, 1995, indicated that the reach was laterally unstable.\nThe State Route 105 crossing of the Nulhegan Riveris a 44-ft-long, two-lane bridge \nconsisting of one 42-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, March 6, 1995). The bridge is supported by vertical, concrete abutments \nwith wingwalls. The channel is skewed approximately 10 degrees to the opening while the \nopening-skew-to-roadway is zero degrees. \nScour protection measures at the site were type-2 stone fill (less than 36 inches diameter) on \nthe upstream right bank, the upstream right wingwall, the right abutment, the downstream \nend of the left abutment and the downstream wingwalls. Additional details describing \nconditions at the site are included in the Level II Summary and Appendices D and E.\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.\nContraction scour for all modelled flows ranged from 1.2 to 1.9 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 6.6 to \n11.0 ft. The worst-case abutment scour also occurred at the 500-year discharge. Total scour \ndepths computed for this site were not below the bottom of the footings, except for the 500-\nyear discharge model at the left abutment. Additional information on scour depths and \ndepths to armoring are included in the section titled “Scour Results”. Scoured-streambed \nelevations, based on the calculated scour depths, are presented in tables 1 and 2. A crosssection of the scour computed at the bridge is presented in figure 8. Scour depths were \ncalculated assuming an infinite depth of erosive material and a homogeneous particle-size \ndistribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr96586","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Boehmler, E.M., and Degnan, J.R., 1996, Level II scour analysis for Bridge 94 (FERDVT01050094) on State Route 105, crossing the Nulhegan River, Ferdinand, Vermont: U.S. Geological Survey Open-File Report 96-586, iv, 47 p., https://doi.org/10.3133/ofr96586.","productDescription":"iv, 47 p.","numberOfPages":"52","costCenters":[],"links":[{"id":162643,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr96586.PNG"},{"id":279283,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1996/0586/report.pdf"}],"country":"United States","state":"Vermont","city":"Ferdinand","otherGeospatial":"Nulhegan River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -71.858382,44.626732 ], [ -71.858382,44.820132 ], [ -71.662301,44.820132 ], [ -71.662301,44.626732 ], [ -71.858382,44.626732 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b16e4b07f02db6a5597","contributors":{"authors":[{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240354,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Degnan, James R. 0000-0002-5665-9010 jrdegnan@usgs.gov","orcid":"https://orcid.org/0000-0002-5665-9010","contributorId":498,"corporation":false,"usgs":true,"family":"Degnan","given":"James","email":"jrdegnan@usgs.gov","middleInitial":"R.","affiliations":[{"id":466,"text":"New England Water Science Center","active":true,"usgs":true},{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240353,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ]}