YADKI-020 Final Report

DAM HYDRAULIC CAPACITY
ASSESSMENT REPORT
(DRAFT)
DEEP CREEK WS #12 (PL-566)
YADKI-020
YADKIN 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 Deep Creek WS #12 (Pl-566) in Yadkin 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 =
353.4
268.4
281.6
295.2
309.2
323.5
338.2
942.5
943.0
943.5
944.0
944.5
ELEVATION
940.0
940.5
941.0
941.5
942.0
11.5
14.1
16.8
STORAGE (ACRE-FT)
0.0
0.8
2.0
3.4
5.1
7.0
9.2
924.0
921.0
921.5
922.0
922.5
923.0
923.5
919.5
939.4
ELEVATION
919.5
920.0
920.5
STORAGE (ACRE-FT)
231.1
243.2
255.6
77.89
81
SCS Type 2
SPILLWAY
Primary
Auxiliary
TYPE
Riser / Barrel
Grass Lined Trapezoidal Channel
ELEVATION
24 HOUR - 200 YEAR EVENT, 8.8 INCHES, ELEVATION 941.6 (1.2 FT FREE-BOARD)
24 HOUR - 100 YEAR EVENT, 7.9 INCHES, ELEVATION 941.1 (1.7 FT FREE-BOARD)
24 HOUR - 50 YEAR EVENT, 7.04 INCHES, ELEVATION 940.6 (2.2 FT FREE-BOARD)
24 HOUR - 25 YEAR EVENT, 6.21 INCHES, ELEVATION 940.1 (2.7 FT FREE-BOARD)
SUMMARY OF INPUT PARAMETERS
1.69
SUMMARY SHEET OF HYDRAULIC CAPACITY RESULTS
DEEP CREEK WS #12 (PL-566), YADKI-020
ANALYSIS PERFORMED BY: S. MURPHY, HDR
TOP OF DAM ELEVATION = 942.8
24 HOUR - 1000 YEAR EVENT, 11 INCHES, ELEVATION 942.6 (0.2 FT FREE-BOARD)
24 HOUR - 500 YEAR EVENT, 10 INCHES, ELEVATION 942.1 (0.7 FT FREE-BOARD)
YADKI-020DEEP CREEK WS #12 (PL-566)OCTOBER 27, 2020
1018.0
NOT TO SCALE
849.8
876.4
903.6
931.3
959.6
988.5
700.8
724.4
748.5
773.1
798.2
823.7
568.5
589.3
610.7
632.5
654.8
677.5
453.0
471.1
489.7
508.7
528.2
548.1
369.0
384.9
401.4
418.2
435.4
957.5
958.0
958.5
959.0
959.5
954.5
955.0
955.5
956.0
956.5
957.0
951.5
952.0
952.5
953.0
953.5
954.0
948.5
949.0
949.5
950.0
950.5
951.0
945.5
946.0
946.5
947.0
947.5
948.0
945.0
186.6
197.1
208.1
219.4
131.4
139.7
148.3
157.3
166.7
176.4
88.3
94.8
101.5
108.5
115.7
123.4
54.4
59.5
64.7
70.3
76.0
82.0
29.6
33.2
37.0
41.0
45.3
49.7
19.7
22.8
26.1
939.0
939.5
936.0
936.5
937.0
937.5
938.0
938.5
933.0
933.5
934.0
934.5
935.0
935.5
930.0
930.5
931.0
931.5
932.0
932.5
927.0
927.5
928.0
928.5
929.0
929.5
924.5
925.0
925.5
926.0
926.5
YADKI-020DEEP CREEK WS #12 (PL-566)OCTOBER 27, 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
Deep Creek WS #12 (PI-566) - YADKI-020 - Watershed Boundary
Legend
Longest FlowPath
Watershed Bound ary
0 0.55 1.10.275 Miles
Date: 10 /5/2020
/Drainage Area: 1.69 Square MilesFlowpath Length: 3.3 miles

APPENDIX B

Lag Time Calculation
Dam No:YADKI-020 Date:10/23/2020
Dam Name:Deep Creek WS #12 (Pl-566)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 =77.8898 from NRCS CN Calculation
S =2.83865 in.
Mean Basin Slope Y =6.00447 %from Watershed Mean slope
Longest Flowpath:3.28 mi.from Watershed Longest flowpath
Flow Length l =17318.4 ft.
Time of Concentration Tc =2.26 Hours Tc =135 mins
Lag Time TL =1.35 Hours TL =81 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 27737 100 2773745 26701 100 2670072 139310 100 13931003
Developed, Open Space Open space - Fair condition (grass cover 50% to 75%)0 49 0 647354 69 44667455 2477689 79 195737457 143046 84 12015897
Developed, Low Intensity Residential districts by average lot size: 1/3 acre 0 57 0 72067 72 5188849 399848 81 32387666 0 86 0
Developed, Medium Intensity Residential districts by average lot size: 1/8 acre 0 77 0 0 85 0 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 4009169 60 240550147 2369690 73 172987398 1251186 79 98843685
Evergreen Forest Woods - Fair 0 36 0 121943 60 7316600 112908 73 8242258 151959 79 12004795
Mixed Forest Woods - Fair 0 36 0 1597479 60 95848757 1118937 73 81682420 528505 79 41751889
Shrub/Scrub Brush - Fair 0 35 0 83828 56 4694359 51796 70 3625718 0 77 0
Herbaceuous Herbaceuous - Fair 0 60 0 355579 71 25246143 380588 81 30827619 96953 89 8628792
Hay/Pasture Pasture - Fair 0 49 0 3571055 69 246402785 9683144 79 764968404 350660 84 29455417
Cultivated Crops Row crops (SR + CR) - Poor 0 71 0 3395661 80 271652850 13764709 87 1197529695 305369 90 27483180
Woody Wetlands Not Available 0 80 0 0 85 0 0 90 0 0 95 0
Emergent Herbaceuous Wetlands Not Available 0 80 0 0 85 0 0 90 0 0 95 0 Weighted CN=77.89
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): Boonville, North Carolina USA
Station Name: -
Latitude: 36.156751°
Longitude: -80.745728°
Elevation (USGS): 1012.75 ft
PRECIPITATION FREQUENCY ESTIMATES
by
duration
for ARI
(years):1 2 5 10 25 50 100 200 500 1000
5-min:0.355 0.421 0.497 0.553 0.62 0.668 0.714 0.757 0.809 0.848
10-min:0.566 0.673 0.796 0.884 0.988 1.06 1.13 1.2 1.28 1.34
15-min:0.708 0.846 1.01 1.12 1.25 1.35 1.43 1.51 1.61 1.68
30-min:0.97 1.17 1.43 1.62 1.86 2.03 2.2 2.36 2.56 2.71
60-min:1.21 1.47 1.83 2.11 2.47 2.75 3.02 3.3 3.68 3.96
2-hr:1.43 1.74 2.19 2.54 3.02 3.39 3.77 4.16 4.7 5.13
3-hr:1.55 1.88 2.38 2.76 3.29 3.71 4.14 4.59 5.22 5.72
6-hr:1.93 2.33 2.94 3.42 4.07 4.6 5.14 5.71 6.5 7.13
12-hr:2.37 2.88 3.62 4.2 5 5.65 6.32 7.02 7.99 8.77
24-hr:2.87 3.49 4.43 5.17 6.21 7.04 7.9 8.8 10 11
2-day:3.42 4.13 5.2 6.02 7.16 8.05 8.97 9.92 11.2 12.2
3-day:3.64 4.39 5.49 6.35 7.51 8.44 9.39 10.4 11.7 12.8
4-day:3.86 4.65 5.79 6.67 7.87 8.83 9.8 10.8 12.2 13.3
7-day:4.42 5.29 6.46 7.37 8.58 9.52 10.5 11.5 12.8 13.8
10-day:5.06 6.04 7.27 8.22 9.46 10.4 11.4 12.4 13.7 14.7
20-day:6.79 8.04 9.51 10.6 12.2 13.3 14.5 15.7 17.2 18.4
30-day:8.43 9.93 11.5 12.6 14 15.1 16.1 17.2 18.5 19.4
45-day:10.7 12.5 14.1 15.4 16.9 18.1 19.2 20.2 21.6 22.5
60-day:12.7 14.8 16.6 18 19.7 21 22.2 23.4 24.9 26
Date/time (GMT): Fri Oct 23 17:05:08 2020
pyRunTime: 0.0347418785095

APPENDIX F
Outlet Works Rating Curves

Total outlet discharge from the spillway systemClient:NCEMDate:10/20/2020Project:Overtopping StudyEngineer:T.CarterDam:Deep Creek WS #12 (PI-566)Dam No.YADKI-020Reservior Water Level (RWS) Elevation (ft)Primary spillway discharge (cfs)Emergency spillway discharge (cfs)Total discharge from the spillway system (cfs)919.50.00.00.0920.016.50.016.5920.516.80.016.8921.017.00.017.0921.517.30.017.3922.017.50.017.5922.517.80.017.8923.018.00.018.0923.518.20.018.2924.018.50.018.5924.518.70.018.7925.018.90.018.9925.519.10.019.1926.019.40.019.4926.519.60.019.6927.019.80.019.8927.520.00.020.0928.020.20.020.2928.520.40.020.4929.020.60.020.6929.520.80.020.8930.021.00.021.0930.521.20.021.2931.021.40.021.4931.521.60.021.6932.021.80.021.8932.522.00.022.0933.022.20.022.2933.522.40.022.4934.022.60.022.6934.522.80.022.8935.022.90.022.9935.523.10.023.1936.023.30.023.3936.523.50.023.5937.023.70.023.7937.523.80.023.8938.024.00.024.0938.524.20.024.2939.024.40.024.4939.524.510.034.5940.024.7148.8173.5940.524.9373.6398.5941.025.0663.0688.0941.525.21008.31033.5942.025.41404.81430.2942.525.51849.41874.9943.025.72340.02365.7943.525.92875.22901.1944.026.03453.93479.9944.526.24075.24101.4945.026.44738.74765.0945.526.55443.85470.30.01000.02000.03000.04000.05000.06000.07000.08000.09000.0915.0 920.0 925.0 930.0 935.0 940.0 945.0 950.0Total discharge from the spillway system (cfs)Reservior Water Level (RWS) Elevation (ft)The whole spillway system rating curve (cfs)
946.026.76190.26216.9946.526.86977.77004.6947.027.07806.27833.2947.527.18675.58702.7948.027.39585.79613.0