YADKI-033 Final Report

DAM HYDRAULIC CAPACITY
ASSESSMENT REPORT
(DRAFT)
DEEP CREEK W/S DAM #21
YADKI-033
YADKIN COUNTY, NC
PREPARED BY:
WOOD E&I Solutions
2020
EXECUTIVE SUMMARY
A hydraulic capacity analysis was completed for the Deep Creek #21 Dam 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. 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 =
516.1
538.4
561.1
584.2
758.0830.9
826.9
827.4
827.9
59.8
808.9
809.4
809.9
810.4
810.9
631.8
656.2
44.3
51.8
8.7
805.9
806.4
807.4
807.9
808.4
0.0
4.2
13.7
19.0
24.6
30.7
37.3
828.4
828.9
829.4
829.9
830.4
825.9
826.4
SUMMARY SHEET OF HYDRAULIC CAPACITY RESULTS
DEEP CREEK #21  DAM, YADKI‐033
SPILLWAY
ANALYSIS PERFORMED BY:  SURBHI THAKUR, WOOD
24 HOUR ‐ 1000 YEAR EVENT, 10.90  INCHES, ELEVATION 832.2 (0.8 FT FREEBOARD)
24 HOUR ‐ 500 YEAR EVENT, 9.95 INCHES, ELEVATION 831.7 (1.3 FT FREEBOARD)
24 HOUR ‐ 200 YEAR EVENT, 8.74 INCHES, ELEVATION 831.0 (2.0 FT FREEBOARD)
TOP OF DAM ELEVATION  = 833
Principal
24 HOUR ‐ 100 YEAR EVENT, 7.85 INCHES, ELEVATION 830.4 (2.6 FT FREEBOARD)
ELEVATIONTYPE
24 HOUR ‐ 50 YEAR EVENT, 7.01 INCHES, ELEVATION 828.8 (4.2 FT FREEBOARD)
24 HOUR ‐ 25 YEAR EVENT, 6.18 INCHES, ELEVATION 826.2 (6.8 FT FREEBOARD)
SUMMARY OF INPUT PARAMETERS
SCS  Type 2
4.02
70.29
119
Riser/Barrel 823.9
STORAGE (ACRE‐FT)ELEVATION ELEVATION STORAGE (ACRE‐FT)
Auxiliary Grass‐Lined Trapezoidal Channel
806.9
830.0
681.0
706.2
731.9
607.8
DEEP CREEK #21 DAM YADKI‐033 September  11, 2020
1607.7
1648.2
1689.4
1697.7
1415.5
1452.7
1490.4
1528.9
1568.0
1238.6
1272.8
1307.7
1343.0
1379.0
1074.9
1106.6
1138.8
1171.6
1204.8
923.8
953.1
982.8
1013.0
1043.7
784.5
811.5
838.8
866.7
895.0
843.4
843.9
844.4
844.9
835.9
836.4
836.9
837.4
837.9
833.4
833.9
834.4
834.9
835.4
831.4
831.9
832.4
832.9
845.0
840.9
841.4
841.9
842.4
842.9
838.4
838.9
839.4
839.9
840.4
824.9
825.4
233.7
249.1
265.1
281.7
298.8
164.9
177.7
191.0
204.8
219.0
410.9
431.2
451.8
472.9
494.3
316.4
334.4
352.9
371.8
391.1
68.2
106.9
117.6
128.8
140.4
152.5
823.9
824.4
77.2
86.7
96.5
821.4
821.9
822.4
822.9
823.4
818.9
819.4
819.9
820.4
820.9
816.4
816.9
817.4
817.9
818.4
813.9
814.4
814.9
815.4
815.9
811.4
811.9
812.4
812.9
813.4
NOT TO SCALE
DEEP CREEK #21 DAM YADKI‐033 September  11, 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 - Yadki-033 - Watershed Boundary
Legend
Longest FlowPath
Watershed Boundary
0 0.5 10.25 Miles
Date: 7/29/2020
/Drainage Area: 4.02 Square Miles Flowpath Length: 5.33 Miles
APPENDIX B
Lag Time Calculation
Dam No: Yadki-033 Date: 7/29/2020
Dam Name: Deep Creek #21 Dam Engineer: S. Thakur
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 = 70.29 from NRCS CN
S =4.22677 in.
Mean Basin Slope Y = 9.4692 % from Watershed Mean slope
Longest Flowpath: 5.3335 mi. from Watershed Longest flowpath
Flow Length l =28160.9 ft.
Time of Concentration Tc = 3.29 Hours Tc = 198 mins
Lag Time TL =1.98 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.) CNOpen Water Not Available 0 100 0 381083 100 38108262 151709 100 15170893 0100 0Developed, Open Space  Open space ‐ Fair condition (grass cover 50% to 75%) 0 49 0 5605861 69 386804385 5693001 79 449747075 98537 84 8277087Developed, Low IntensityResidential districts by average lot size: 1/3 acre 0 57 0 1122129 72 80793306 1718018 81 139159471 75219 86 6468856Developed, Medium IntensityResidential districts by average lot size: 1/8 acre 0 77 0 23081 85 1961875 164288 90 14785940 10029 92 922640Developed, High IntensityUrban districts ‐ Commercial and business 0 89 0 1419 92 130527 8268 94777233 0 95 0Barren Land Newly graded areas 0 77 0 0 86 0 0 91 0 0 94 0Deciduous Forest Woods ‐ Fair 0 36 0 27526982 60 1651618904 8154997 73 595314809 1871228 79 147827017Evergreen Forest Woods ‐ Fair 0 36 0 2610312 60 156618707 792932 73 57884027 26582 79 2099939Mixed Forest Woods ‐ Fair 0 36 0 7169824 60 430189435 2279526 73 166405401 669779 79 52912528Shrub/Scrub Brush ‐ Fair 0 35 0 1499797 56 83988633 453780 70 31764579 227733 77 17535435Herbaceuous Herbaceuous ‐ Fair 0 60 0 1641452 71 116543084 527232 81 42705823 99996 89 8899628Hay/Pasture Pasture ‐ Fair 0 49 0 16425529 69 1133361510 10817360 79 854571407 212682 84 17865319Cultivated Crops Row crops  (SR + CR) ‐ Poor 0 71 0 7897465 80 631797215 5469631 87 475857931 207638 90 18687412Woody Wetlands Not Available 0 80 0 86214 85 7328190 0 90 0 320647 95 30461461Emergent Herbaceuous Wetlands Not Available 0 80 0 0 85 0 0 90 0 0 95 0 Weighted CN= 70.29NOTE: 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 accurateNOTE: double‐check the exported attribute table has the same table format as the "Export_Output" table
APPENDIX D
Hyetograph Results Used for Analyses
0.02.04.06.08.010.012.00123456789101112131415161718192021222324Cumulative Depth (in)Time (hrs)Hyetographs for 24-Hour SCS Type II Rainfall Distributions25YR50YR100YR200YR500YR1000YR
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): Hamptonville, North Carolina USA
Station Name: ‐
Latitude: 36.1067°
Longitude: ‐80.7479°
Elevation (USGS): None None
PRECIPITATION FREQUENCY ESTIMATES
by 
duration 
for ARI 
(years):1 2 5 10 25 50 100 200 500 1000
5‐min: 0.357 0.423 0.499 0.554 0.621 0.669 0.714 0.756 0.807 0.845
10‐min: 0.57 0.676 0.799 0.887 0.99 1.07 1.13 1.2 1.28 1.33
15‐min: 0.712 0.85 1.01 1.12 1.26 1.35 1.43 1.51 1.61 1.67
30‐min: 0.976 1.17 1.44 1.63 1.86 2.03 2.2 2.35 2.56 2.7
60‐min: 1.22 1.47 1.84 2.12 2.48 2.75 3.03 3.3 3.67 3.95
2‐hr: 1.44 1.75 2.2 2.55 3.02 3.39 3.76 4.15 4.68 5.09
3‐hr: 1.55 1.88 2.38 2.76 3.29 3.71 4.13 4.58 5.2 5.69
6‐hr: 1.93 2.33 2.94 3.41 4.06 4.59 5.12 5.68 6.46 7.08
12‐hr: 2.36 2.86 3.6 4.18 4.98 5.62 6.29 6.98 7.94 8.7
24‐hr: 2.87 3.48 4.42 5.16 6.18 7.01 7.85 8.74 9.95 10.9
2‐day: 3.41 4.12 5.18 5.99 7.11 7.99 8.9 9.82 11.1 12.1
3‐day: 3.63 4.38 5.47 6.31 7.46 8.37 9.3 10.3 11.6 12.6
4‐day: 3.85 4.63 5.76 6.63 7.82 8.75 9.71 10.7 12 13.1
7‐day: 4.4 5.27 6.43 7.32 8.52 9.45 10.4 11.3 12.6 13.6
10‐day: 5.05 6.02 7.25 8.18 9.41 10.4 11.3 12.3 13.5 14.5
20‐day: 6.76 8.01 9.47 10.6 12.1 13.2 14.4 15.6 17.1 18.3
30‐day: 8.4 9.89 11.4 12.5 13.9 15 16 17 18.3 19.3
45‐day: 10.6 12.4 14.1 15.3 16.8 18 19 20.1 21.4 22.4
60‐day: 12.6 14.7 16.5 17.9 19.6 20.9 22.1 23.2 24.7 25.8
Date/time (GMT):  Tue Jun 23 11:32:22 2020
pyRunTime:  0.0162668228149
APPENDIX F
Outlet Works Rating Curves
Total outlet discharge from the spillway systemClient: NCFMPDate: 9/11/2020Project: Overtopping StudyEngineer: S. ThakurDam: Deep Creek W/S #21 Dam No. YADKI-033Reservior Water Level (RWS) Elevation (ft)Primary 1 spillway discharge (cfs)Emergency spillway discharge (cfs)Total discharge from the spillway system (cfs)805.9 0.0 0.0 0.0806.7 5.7 0.0 5.7807.5 10.0 0.0 10.0808.3 12.8 0.0 12.8809.1 15.2 0.0 15.2809.9 17.2 0.0 17.2810.7 19.0 0.0 19.0811.5 20.6 0.0 20.6812.3 22.2 0.0 22.2813.1 23.6 0.0 23.6813.9 24.9 0.0 24.9814.7 26.2 0.0 26.2815.5 27.4 0.0 27.4816.3 28.6 0.0 28.6817.1 29.7 0.0 29.7817.9 30.8 0.0 30.8818.7 31.8 0.0 31.8819.5 32.8 0.0 32.8820.3 33.8 0.0 33.8821.1 34.8 0.0 34.8821.9 35.7 0.0 35.7822.7 36.6 0.0 36.6823.5 37.5 0.0 37.5824.3 54.8 0.0 54.8825.1 120.1 0.0 120.1825.9 121.6 0.0 121.6826.7 123.1 0.0 123.1827.5 124.6 0.0 124.6828.3 126.1 0.0 126.1829.1 127.6 0.0 127.6829.9 129.0 0.0 129.0830.7 130.4 349.3 479.7831.5 131.9 1095.7 1227.5832.3 133.3 2080.3 2213.6833.1 134.6 3277.7 3412.4833.9 136.0 4656.5 4792.5834.7 137.4 6242.2 6379.5835.5 138.7 7931.1 8069.8836.3 140.0 9723.0 9863.1837.1 141.4 11632.6 11774.0837.9 142.7 13653.1 13795.7838.7 144.0 15778.6 15922.6839.5 145.2 18004.3 18149.5840.3 146.5 20325.7 20472.2841.1 147.8 22739.2 22886.9841.9 149.0 25241.3 25390.3842.7 150.3 27828.9 27979.1843.5 151.5 30499.4 30650.9844.3 152.7 33250.2 33402.90.05000.010000.015000.020000.025000.030000.035000.040000.0800.0 805.0 810.0 815.0 820.0 825.0 830.0 835.0 840.0 845.0 850.0Total discharge from the spillway system (cfs)Reservior Water Level (RWS) Elevation (ft)The whole spillway system rating curve (cfs)