YADKI-019 Final Report

DAM HYDRAULIC CAPACITY
ASSESSMENT REPORT
(DRAFT)
DEEP CREEK WS #19A (PL-566)
YADKI-019
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 #19a (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 =
Auxiliary Grass Lined Trapezoidal Channel 991.9
595.7
626.7
658.8
692.1
726.7
762.6
994.4
994.9
995.4
995.9
ELEVATION
991.9
992.4
992.9
993.4
993.9
21.3
25.9
STORAGE (ACRE-FT)
0.0
2.4
4.8
7.5
10.4
13.6
17.2
972.9
973.4
973.9
974.4
974.9
975.4
971.4
991.8
ELEVATION
971.4
971.9
972.4
STORAGE (ACRE-FT)
507.8
536.2
565.5
75.53
119
SCS Type 2
SPILLWAY
Primary
Auxiliary
TYPE
Riser / Barrel
Grass Lined Trapezoidal Channel
ELEVATION
24 HOUR - 200 YEAR EVENT, 8.82 INCHES, ELEVATION 993.9 (1.3 FT FREE-BOARD)
24 HOUR - 100 YEAR EVENT, 7.92 INCHES, ELEVATION 993.4 (1.8 FT FREE-BOARD)
24 HOUR - 50 YEAR EVENT, 7.05 INCHES, ELEVATION 992.9 (2.3 FT FREE-BOARD)
24 HOUR - 25 YEAR EVENT, 6.21 INCHES, ELEVATION 992.4 (2.8 FT FREE-BOARD)
SUMMARY OF INPUT PARAMETERS
3.53
SUMMARY SHEET OF HYDRAULIC CAPACITY RESULTS
DEEP CREEK WS #19A (PL-566), YADKI-019
ANALYSIS PERFORMED BY: S. MURPHY, HDR
TOP OF DAM ELEVATION = 995.2
24 HOUR - 1000 YEAR EVENT, 11.1 INCHES, ELEVATION 995 (0.2 FT FREE-BOARD)
24 HOUR - 500 YEAR EVENT, 10.1 INCHES, ELEVATION 994.5 (0.7 FT FREE-BOARD)
YADKI-019DEEP CREEK WS #19A (PL-566)OCTOBER 27, 2020
2607.2
NOT TO SCALE
2131.4
2206.5
2283.2
2361.7
2441.8
2523.6
1716.5
1781.5
1848.1
1916.5
1986.4
2058.1
1358.1
1414.1
1471.6
1530.5
1591.0
1653.1
1053.5
1100.7
1149.3
1199.3
1250.7
1303.6
799.9
838.6
878.7
920.2
963.2
1007.6
1009.4
1009.9
1010.4
1010.9
1011.4
1006.4
1006.9
1007.4
1007.9
1008.4
1008.9
1003.4
1003.9
1004.4
1004.9
1005.4
1005.9
1000.4
1000.9
1001.4
1001.9
1002.4
1002.9
997.4
997.9
998.4
998.9
999.4
999.9
996.4
996.9
403.1
427.9
453.7
480.3
272.4
291.9
312.5
333.8
356.1
379.1
173.8
188.1
203.2
219.2
236.0
253.8
104.0
113.9
124.4
135.6
147.6
160.3
55.1
62.2
69.7
77.6
85.9
94.7
30.9
36.3
42.2
48.4
990.9
991.4
987.9
988.4
988.9
989.4
989.9
990.4
984.9
985.4
985.9
986.4
986.9
987.4
981.9
982.4
982.9
983.4
983.9
984.4
978.9
979.4
979.9
980.4
980.9
981.4
975.9
976.4
976.9
977.4
977.9
978.4
YADKI-019DEEP CREEK WS #19A (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 #19a (PI-566) - YADKI-019 - Watershed Boundary
Legend
Longest FlowPath
Watershed Bound ary
0 1 20.5 Miles
Date: 10 /5/2020
/Drainage Area: 3.53 Square MilesFlowpath Length: 5.1 miles

APPENDIX B

Lag Time Calculation
Dam No:YADKI-019 Date:10/23/2020
Dam Name:Deep Creek WS #19a (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 =75.5317 from NRCS CN Calculation
S =3.23947 in.
Mean Basin Slope Y =6.54513 %from Watershed Mean slope
Longest Flowpath:5.13 mi.from Watershed Longest flowpath
Flow Length l =27086.4 ft.
Time of Concentration Tc =3.31 Hours Tc =199 mins
Lag Time TL =1.99 Hours TL =119 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 148060 100 14806042 49521 100 4952075 248044 100 24804359
Developed, Open Space Open space - Fair condition (grass cover 50% to 75%)0 49 0 1397968 69 96459761 3718497 79 293761301 157475 84 13227864
Developed, Low Intensity Residential districts by average lot size: 1/3 acre 0 57 0 231342 72 16656606 1173949 81 95089880 7094 86 610092
Developed, Medium Intensity Residential districts by average lot size: 1/8 acre 0 77 0 0 85 0 3271 90 294352 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 10993534 60 659612018 4944247 73 360930043 2802212 79 221374740
Evergreen Forest Woods - Fair 0 36 0 390339 60 23420329 878388 73 64122296 29401 79 2322679
Mixed Forest Woods - Fair 0 36 0 3501853 60 210111162 2009078 73 146662669 1074138 79 84856869
Shrub/Scrub Brush - Fair 0 35 0 740291 56 41456297 262506 70 18375449 158419 77 12198234
Herbaceuous Herbaceuous - Fair 0 60 0 1471306 71 104462738 1483755 81 120184147 17396 89 1548259
Hay/Pasture Pasture - Fair 0 49 0 11759243 69 811387748 23395118 79 1848214322 1487095 84 124915961
Cultivated Crops Row crops (SR + CR) - Poor 0 71 0 9457475 80 756598030 13334758 87 1160123915 546130 90 49151656
Woody Wetlands Not Available 0 80 0 22234 85 1889867 6042 90 543769 281726 95 26763929
Emergent Herbaceuous Wetlands Not Available 0 80 0 132 85 11230 0 90 0 203305 95 19313965 Weighted CN=75.53
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: 36.17775°
Longitude: -80.746974°
Elevation (USGS): 1066.41 ft
PRECIPITATION FREQUENCY ESTIMATES
by
duration
for ARI
(years):1 2 5 10 25 50 100 200 500 1000
5-min:0.354 0.42 0.496 0.552 0.62 0.668 0.714 0.757 0.809 0.849
10-min:0.565 0.672 0.795 0.883 0.988 1.06 1.13 1.2 1.28 1.34
15-min:0.707 0.844 1.01 1.12 1.25 1.35 1.43 1.51 1.61 1.68
30-min:0.969 1.17 1.43 1.62 1.85 2.03 2.2 2.36 2.56 2.72
60-min:1.21 1.46 1.83 2.11 2.47 2.75 3.02 3.31 3.68 3.97
2-hr:1.43 1.74 2.19 2.54 3.02 3.39 3.78 4.17 4.71 5.14
3-hr:1.55 1.88 2.37 2.76 3.29 3.71 4.14 4.59 5.22 5.72
6-hr:1.93 2.34 2.94 3.42 4.08 4.61 5.15 5.72 6.51 7.14
12-hr:2.38 2.88 3.62 4.21 5.01 5.66 6.33 7.03 8.01 8.79
24-hr:2.87 3.49 4.43 5.18 6.21 7.05 7.92 8.82 10.1 11.1
2-day:3.42 4.14 5.2 6.03 7.17 8.07 9 9.95 11.3 12.3
3-day:3.64 4.4 5.5 6.36 7.53 8.46 9.42 10.4 11.7 12.8
4-day:3.87 4.66 5.79 6.68 7.89 8.85 9.83 10.8 12.2 13.3
7-day:4.42 5.3 6.47 7.38 8.59 9.55 10.5 11.5 12.8 13.9
10-day:5.07 6.05 7.28 8.23 9.48 10.5 11.4 12.4 13.7 14.7
20-day:6.8 8.05 9.53 10.7 12.2 13.4 14.5 15.7 17.3 18.5
30-day:8.44 9.94 11.5 12.6 14.1 15.1 16.2 17.2 18.5 19.5
45-day:10.7 12.5 14.2 15.4 17 18.1 19.2 20.3 21.6 22.6
60-day:12.7 14.8 16.6 18 19.8 21 22.3 23.4 24.9 26
Date/time (GMT): Fri Oct 23 15:48:57 2020
pyRunTime: 0.0612199306488

APPENDIX F
Outlet Works Rating Curves

Total outlet discharge from the spillway systemClient:NCEMDate:10/20/2020Project:Overtopping StudyEngineer:T.CarterDam:Deep Creek WS #19a (PI-566)Dam No.YADKI-019Reservior Water Level (RWS) Elevation (ft)Primary spillway discharge (cfs)Primary spillway 2 discharge (cfs)Emergency spillway discharge (cfs)Total discharge from the spillway system (cfs)971.40.00.00.00.0971.925.40.00.025.4972.425.90.00.025.9972.926.30.00.026.3973.426.70.00.026.7973.927.00.00.027.0974.427.40.00.027.4974.927.80.00.027.8975.428.20.00.028.2975.928.60.00.028.6976.428.90.00.028.9976.929.30.00.029.3977.429.60.00.029.6977.930.00.00.030.0978.430.30.00.030.3978.930.70.00.030.7979.431.00.00.031.0979.931.40.00.031.4980.431.70.00.031.7980.932.00.00.032.0981.432.40.00.032.4981.932.70.00.032.7982.433.00.00.033.0982.933.30.00.033.3983.433.60.00.033.6983.933.90.00.033.9984.434.20.00.034.2984.934.60.00.034.6985.434.90.00.034.9985.935.20.00.035.2986.435.50.00.035.5986.935.70.00.035.7987.436.00.00.036.0987.936.30.00.036.3988.436.60.00.036.6988.936.90.00.036.9989.437.20.00.037.2989.937.50.00.037.5990.437.70.00.037.7990.938.00.00.038.0991.438.30.00.038.3991.938.66.10.044.7992.438.891.469.2199.4992.939.1231.3203.2473.5993.439.4413.3387.0839.7993.939.6632.8617.11289.6994.439.9887.5892.01819.5994.940.21176.01211.62427.7995.440.41497.21575.93113.6995.940.71850.91985.43877.0996.441.02236.62440.64718.2996.941.22654.22942.35637.7997.441.53103.63491.36636.40.02000.04000.06000.08000.010000.012000.014000.016000.0965.0 970.0 975.0 980.0 985.0 990.0 995.0 1000.0 1005.0Total discharge from the spillway system (cfs)Reservior Water Level (RWS) Elevation (ft)The whole spillway system rating curve (cfs)
997.941.73584.94088.27714.9998.442.04098.24734.18874.2998.942.24643.65429.610115.4999.442.55221.26175.611439.3999.942.75831.36973.112847.11000.443.06474.07822.814339.8