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ROWAN-063 Final Report
DAM HYDRAULIC CAPACITY ASSESSMENT REPORT (DRAFT) SALISBURY COMMUNITY PARK DAM ROWAN-063 ROWAN COUNTY, NC PREPARED BY: HDR Engineering Inc. of the Carolinas under contract with WOOD E&I Solutions 2020 EXECUTIVE SUMMARY A hydraulic capacity analysis was completed for the Salisbury Community Park Dam in Rowan County, North Carolina. The purpose of the study was to analyze the existing potential of the dam for overtopping during predetermined specified rainfall events using the North Carolina Dam Safety defined process and templates. The analyses were completed using the United States Army Corps of Engineers developed software Hydrologic Engineering Center – Hydrologic Modeling System (HEC-HMS) in combination with Arc-GIS to develop required input parameters. The rainfall events included in the analyses consist of 24-hour durations with return periods of 25 years, 50 years, 100 years, 200 years, 500 years and 1000 years. Results of the analyses indicate that this structure is hydraulically adequate for 25 years, 50 years, 100 years, 200 years, 500 years, and 1000 years rainfall events. Data, input parameters, and final results can be found on the attached summary sheets and in the appendices of this report as well as in the associated electronic file in which all program files are stored. Drainage Area (Sq. Mi.)= Curve Number = Lag Time (min.)= Rainfall Distribution Methods = 24 HOUR - 200 YEAR EVENT, 7.88 INCHES, ELEVATION 777.7 (2.3 FT FREE-BOARD) 24 HOUR - 100 YEAR EVENT, 7.13 INCHES, ELEVATION 777.5 (2.5 FT FREE-BOARD) 24 HOUR - 50 YEAR EVENT, 6.4 INCHES, ELEVATION 777.2 (2.8 FT FREE-BOARD) 24 HOUR - 25 YEAR EVENT, 5.69 INCHES, ELEVATION 777 (3 FT FREE-BOARD) SUMMARY OF INPUT PARAMETERS 0.15 SUMMARY SHEET OF HYDRAULIC CAPACITY RESULTS SALISBURY COMMUNITY PARK DAM, ROWAN-063 ANALYSIS PERFORMED BY: S. MURPHY, HDR TOP OF DAM ELEVATION = 780 24 HOUR - 1000 YEAR EVENT, 9.69 INCHES, ELEVATION 778.2 (1.8 FT FREE-BOARD) 24 HOUR - 500 YEAR EVENT, 8.89 INCHES, ELEVATION 778 (2 FT FREE-BOARD) 69.19 33 SCS Type 2 SPILLWAY Primary Auxiliary TYPE Riser / Barrel Riprap Lined Trapezoidal channel ELEVATION 777.5 778.0 778.5 779.0 779.5 780.0 776.0 777.6 ELEVATION 776.0 776.5 777.0 STORAGE (ACRE-FT) 287.9 298.9 310.2 STORAGE (ACRE-FT) 0.0 4.1 8.2 12.5 17.0 21.5 26.2 780.5 ELEVATION 796.5 797.0 797.5 798.0 798.5 31.1 36.1 41.3 321.6 333.4 345.3 357.6 370.1 382.8 799.0 799.5 800.0 800.5 801.0 395.9 ROWAN-063SALISBURY COMMUNITY PARK DAM SEPTEMBER 10, 2020 785.0 785.5 786.0 781.0 781.5 782.0 782.5 783.0 783.5 784.0 784.5 792.5 789.5 790.0 790.5 791.0 791.5 792.0 786.5 787.0 787.5 788.0 788.5 789.0 190.8 199.5 208.5 142.6 150.2 158.0 165.9 174.0 182.3 100.3 107.0 113.8 120.8 127.9 135.1 63.3 69.2 75.1 256.4 266.7 217.6 227.0 236.6 81.2 87.4 93.8 46.6 52.0 57.6 480.1 495.2 801.5 811.0 811.5 812.0 812.5 813.0 813.5 802.0 802.5 803.0 803.5 804.0 804.5 806.5 807.0 807.5 808.0 808.5 809.0 809.5 810.0 810.5 805.0 805.5 806.0 510.6 526.2 542.2 558.5 409.2 422.8 436.7 450.9 465.4 684.4 704.3 724.6 745.4 766.5 788.1 575.1 592.1 609.6 627.5 646.0 665.0 953.5 NOT TO SCALE 810.2 832.8 855.8 879.4 903.6 928.3815.5 816.0 277.2 795.5 796.0 793.0 793.5 794.0 794.5 795.0 814.0 814.5 815.0246.4 ROWAN-063SALISBURY COMMUNITY PARK DAM SEPTEMBER 10, 2020 APPENDIX A Watershed Boundary Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P,NRCan, Esri Japan, METI, Esri China (Hong Kong), Esri Korea,Esri (Thailand), NGCC, (c) OpenStreetMap contributors, and theGIS User Community Salisbury Community Park Dam - ROWAN-063 - Watershed Boundary Legend LongestFlowPath WatershedBoundary 0 0.15 0.30.075 Miles Date: 8/31/2020 /Drainage Area: 0.15 Square MilesFlowpath Length: 4108.5 feet APPENDIX B Lag Time Calculation Dam No:ROWAN-063 Date:9/4/2020 Dam Name:Salisbury Community Park Dam Engineer:K. Trefzger Maximum Potential Retention (inches):S =(1000/cn')-10 Time of Concentration (hours):Tc =l0.8*(S+1)0.7 1140*Y0.5 Basin Data:Input Values in yellow Curve Number CN =69.1905 from NRCS CN Calculation S =4.45285 in. Mean Basin Slope Y =5.80101 %from Watershed Mean slope Longest Flowpath:0.77813 mi.from Watershed Longest flowpath Flow Length l =4108.53 ft. Time of Concentration Tc =0.93 Hours Tc =56 mins Lag Time TL =0.56 Hours TL =33 mins APPENDIX C NRCS Curve Number Summary Sheet Change CN according to TR-55 (see tables below) NLCD (2016) Landuse TR-55 Landuse HSG A (sq. ft.)CN HSG B (sq. ft.)CN HSG C (sq. ft.)CN HSG D (sq. ft.)CN Open Water Not Available 0 100 0 32291 100 3229068 0 100 0 200164 100 20016384 Developed, Open Space Open space - Fair condition (grass cover 50% to 75%)0 49 0 233226 69 16092582 5899 79 466025 0 84 0 Developed, Low Intensity Residential districts by average lot size: 1/3 acre 0 57 0 95433 72 6871188 0 81 0 0 86 0 Developed, Medium Intensity Residential districts by average lot size: 1/8 acre 0 77 0 63338 85 5383722 0 90 0 0 92 0 Developed, High Intensity Urban districts - Commercial and business 0 89 0 0 92 0 0 94 0 0 95 0 Barren Land Newly graded areas 0 77 0 0 86 0 0 91 0 0 94 0 Deciduous Forest Woods - Fair 0 36 0 1164041 60 69842461 70765 73 5165879 28775 79 2273207 Evergreen Forest Woods - Fair 0 36 0 83132 60 4987903 0 73 0 0 79 0 Mixed Forest Woods - Fair 0 36 0 2810 60 168571 0 73 0 0 79 0 Shrub/Scrub Brush - Fair 0 35 0 0 56 0 0 70 0 0 77 0 Herbaceuous Herbaceuous - Fair 0 60 0 11130 71 790248 0 81 0 8241 89 733446 Hay/Pasture Pasture - Fair 0 49 0 1864026 69 128617789 27646 79 2184067 16343 84 1372786 Cultivated Crops Row crops (SR + CR) - Poor 0 71 0 177076 80 14166091 0 87 0 0 90 0 Woody Wetlands Not Available 0 80 0 0 85 0 0 90 0 0 95 0 Emergent Herbaceuous Wetlands Not Available 0 80 0 1419 85 120646 0 90 0 8266 95 785293 Weighted CN=69.19 NOTE: Curve Numbers are from SCS TR-55 with the exception of assumed HSG A (CN=60) for Herbaceous,Open Water, Woody Wetlands, and Emergent Herbaceous Wetlands. NOTE: double-check all the land types are being calculated and texts are accurate NOTE: double-check the exported attribute table has the same table format as the "Export_Output" table APPENDIX D Hyetograph Results Used for Analysis 0.0 2.0 4.0 6.0 8.0 10.0 12.0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24Cumulative Depth (in)Time (hrs) Hyetographs for 24-Hour SCS Type II Rainfall Distributions 25YR 50YR 100YR 200YR 500YR 1000YR APPENDIX E NOAA Atlas 14 Rainfall Table Point precipitation frequency estimates (inches) NOAA Atlas 14 Volume 2 Version 3 Data type: Precipitation depth Time series type: Partial duration Project area: Ohio River Basin Location name (ESRI Maps): Salisbury, North Carolina USA Station Name: - Latitude: 35.6970999999999° Longitude: -80.5485° Elevation (USGS): 779.01 ft PRECIPITATION FREQUENCY ESTIMATES by duration for ARI (years):1 2 5 10 25 50 100 200 500 1000 5-min:0.383 0.453 0.529 0.582 0.642 0.683 0.719 0.75 0.785 0.808 10-min:0.611 0.724 0.847 0.931 1.02 1.09 1.14 1.19 1.24 1.27 15-min:0.764 0.91 1.07 1.18 1.3 1.38 1.44 1.5 1.56 1.6 30-min:1.05 1.26 1.52 1.71 1.92 2.07 2.21 2.34 2.49 2.59 60-min:1.31 1.58 1.95 2.22 2.56 2.81 3.05 3.28 3.57 3.78 2-hr:1.51 1.83 2.27 2.61 3.04 3.37 3.69 4.01 4.42 4.72 3-hr:1.61 1.94 2.43 2.8 3.28 3.66 4.04 4.41 4.92 5.3 6-hr:1.95 2.35 2.93 3.39 3.99 4.47 4.95 5.44 6.1 6.6 12-hr:2.29 2.76 3.46 4.02 4.77 5.37 5.98 6.61 7.47 8.13 24-hr:2.73 3.29 4.13 4.79 5.69 6.4 7.13 7.88 8.89 9.69 2-day:3.16 3.8 4.74 5.47 6.46 7.24 8.03 8.84 9.93 10.8 3-day:3.36 4.04 5.01 5.77 6.8 7.61 8.44 9.28 10.4 11.3 4-day:3.57 4.28 5.28 6.06 7.14 7.98 8.85 9.73 10.9 11.9 7-day:4.12 4.92 5.98 6.83 7.97 8.88 9.81 10.8 12 13 10-day:4.7 5.59 6.72 7.6 8.77 9.69 10.6 11.6 12.8 13.8 20-day:6.33 7.47 8.81 9.87 11.3 12.4 13.5 14.7 16.2 17.4 30-day:7.83 9.21 10.7 11.8 13.3 14.5 15.6 16.7 18.2 19.3 45-day:9.86 11.5 13.2 14.4 16 17.2 18.4 19.5 21 22.2 60-day:11.7 13.7 15.4 16.8 18.5 19.8 21 22.2 23.8 24.9 Date/time (GMT): Fri Aug 28 16:04:00 2020 pyRunTime: 0.0256578922272 APPENDIX F Outlet Works Rating Curves Total outlet discharge from the spillway system Client:NCEM Date:9/8/2020 Project:Overtopping Study Engineer:K.Trefzger Dam:Salisbury Community Park Dam Dam No.ROWAN-063 Reservior Water Level (RWS) Elevation (ft) Primary spillway discharge (cfs) Emergency spillway discharge (cfs) Total discharge from the spillway system (cfs) 776.0 0.0 0.0 0.0 776.5 13.8 0.0 13.8 777.0 39.0 0.0 39.0 777.5 63.0 0.0 63.0 778.0 72.7 23.3 96.0 778.5 77.6 80.7 158.2 779.0 78.3 160.7 239.0 779.5 79.0 260.6 339.6 780.0 79.7 379.2 459.0 780.5 80.4 516.1 596.5 781.0 81.1 670.8 751.9 781.5 81.8 843.4 925.2 782.0 82.5 1033.7 1116.2 782.5 83.2 1241.9 1325.1 783.0 83.9 1468.2 1552.1 783.5 84.6 1712.6 1797.1 784.0 85.2 1975.3 2060.5 784.5 85.9 2256.5 2342.4 785.0 86.5 2556.5 2643.1 0.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 775.0 776.0 777.0 778.0 779.0 780.0 781.0 782.0 783.0 784.0 785.0 786.0Total discharge from the spillway system (cfs)Reservior Water Level (RWS) Elevation (ft) The whole spillway system rating curve (cfs)