RANDO-027 Final Report

DAM HYDRAULIC CAPACITY
ASSESSMENT REPORT
(DRAFT)
LUCAS LAKE DAM
RANDO-027
RANDOLPH 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 Lucas Lake Dam in Randolph 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 =
Primary
Auxiliary
10700.1
8967.0
9247.4
9531.3
9818.5
10109.0
10402.8
544.0
544.5
545.0
545.5
546.0
ELEVATION
541.5
542.0
542.5
543.0
543.5
1322.5
STORAGE (ACRE-FT)
0.0
134.0
272.3
413.6
557.8
704.7
854.5
525.5
522.5
523.0
523.5
524.0
524.5
525.0
521.0
NA
ELEVATION
521.0
521.5
522.0
STORAGE (ACRE-FT)
8147.3
8417.0
8690.2
1007.1
1163.0
SPILLWAY TYPE
Concrete Ogee
NA
ELEVATION
SUMMARY OF INPUT PARAMETERS
15.56
24 HOUR - 200 YEAR EVENT, 8.15 INCHES, ELEVATION 526.8 (1.7 FT FREE-BOARD)
24 HOUR - 100 YEAR EVENT, 7.4 INCHES, ELEVATION 526.2 (2.3 FT FREE-BOARD)
24 HOUR - 50 YEAR EVENT, 6.66 INCHES, ELEVATION 525.6 (2.9 FT FREE-BOARD)
24 HOUR - 25 YEAR EVENT, 5.94 INCHES, ELEVATION 525 (3.5 FT FREE-BOARD)
SUMMARY SHEET OF HYDRAULIC CAPACITY RESULTS
LUCAS LAKE DAM, RANDO-027
ANALYSIS PERFORMED BY: S. MURPHY, HDR
74.38
147
SCS Type 2
TOP OF DAM ELEVATION = 528.5
24 HOUR - 1000 YEAR EVENT, 9.99 INCHES, ELEVATION 528.3 (0.2 FT FREE-BOARD)
24 HOUR - 500 YEAR EVENT, 9.18 INCHES, ELEVATION 527.7 (0.8 FT FREE-BOARD)
RANDO-027LUCAS LAKE DAM OCTOBER 5, 2020
21671.3
NOT TO SCALE
19153.6
19561.9
19974.7
20392.0
20813.8
21240.3
16798.0
17179.6
17565.4
17955.7
18350.3
18749.8
14602.3
14957.0
15316.3
15680.0
16048.3
16420.9
12570.4
12897.7
13229.5
13565.9
13906.8
14252.2
11001.0
11306.0
11615.2
11929.0
12247.5
561.0
556.0
556.5
557.0
557.5
558.0
558.5
559.0
559.5
560.0
553.0
553.5
554.0
554.5
555.0
555.5
550.0
549.0
549.5
546.5
560.5
550.5
551.0
551.5
552.0
552.5
547.0
547.5
548.0
7361.5
7619.6
7881.3
5648.4
5883.3
6121.6
6363.1
6607.8
6855.6
4310.9
4525.7
4743.9
4965.1
5189.6
5417.3
3093.2
3287.6
548.5
3891.4
4099.5
1994.6
2170.2
2348.8
2530.3
2714.6
2902.2
7106.8
1485.6
1652.2
1821.9
540.5
541.0
537.5
538.0
538.5
539.0
539.5
540.0
534.5
535.0
3485.4
3686.7
535.5
536.0
536.5
537.0
531.5
532.0
532.5
533.0
533.5
534.0
528.5
529.0
529.5
530.0
530.5
531.0
526.0
526.5
527.0
527.5
528.0
RANDO-027LUCAS LAKE DAM OCTOBER 5, 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
Lucas Lake Dam - RANDO-027 - Watershed Boundary
Legend
Longest FlowPath
Watershed Bound ary
0 1 20.5 Miles
Date: 10 /2/2020
/Drainage Ar ea: 15.56 Square MilesFlowpath Length: 8.6 miles

APPENDIX B

Lag Time Calculation
Dam No:RANDO-027 Date:10/8/2020
Dam Name:Lucas Lake 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 =74.3793 from NRCS CN Calculation
S =3.44461 in.
Mean Basin Slope Y =10.5105 %from Watershed Mean slope
Longest Flowpath:8.6 mi.from Watershed Longest flowpath
Flow Length l =45408 ft.
Time of Concentration Tc =4.09 Hours Tc =245 mins
Lag Time TL =2.45 Hours TL =147 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 649080 100 64908002 1026627 100 102662748 11133464 100 #########
Developed, Open Space Open space - Fair condition (grass cover 50% to 75%)0 49 0 17428974 69 1202599224 6368636 79 503122269 11239118 84 944085899
Developed, Low Intensity Residential districts by average lot size: 1/3 acre 0 57 0 8305869 72 598022552 3380642 81 273832035 4967592 86 427212930
Developed, Medium Intensity Residential districts by average lot size: 1/8 acre 0 77 0 2808050 85 238684280 1116145 90 100453050 2052909 92 188867615
Developed, High Intensity Urban districts - Commercial and business 0 89 0 1150512 92 105847112 570265 94 53604903 1195086 95 113533154
Barren Land Newly graded areas 0 77 0 259401 86 22308446 761261 91 69274766 1818893 94 170975957
Deciduous Forest Woods - Fair 0 36 0 69230992 60 4153859543 58485791 73 4269462740 74744601 79 #########
Evergreen Forest Woods - Fair 0 36 0 4304990 60 258299385 3212220 73 234492059 3879521 79 306482131
Mixed Forest Woods - Fair 0 36 0 9105911 60 546354670 8790109 73 641677954 15390702 79 #########
Shrub/Scrub Brush - Fair 0 35 0 5742690 56 321590655 6958889 70 487122220 6163732 77 474607341
Herbaceuous Herbaceuous - Fair 0 60 0 2135378 71 151611855 1704940 81 138100137 2203638 89 196123796
Hay/Pasture Pasture - Fair 0 49 0 31204524 69 2153112177 12776749 79 1009363208 29609152 84 #########
Cultivated Crops Row crops (SR + CR) - Poor 0 71 0 5179267 80 414341341 257668 87 22417078 5957560 90 536180389
Woody Wetlands Not Available 0 80 0 141318 85 12011996 308944 90 27804923 159943 95 15194612
Emergent Herbaceuous Wetlands Not Available 0 80 0 0 85 0 0 90 0 19372 95 1840298 Weighted CN=74.38
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): Randleman, North Carolina USA
Station Name: -
Latitude: 35.767464°
Longitude: -79.847972°
Elevation (USGS): 600.36 ft
PRECIPITATION FREQUENCY ESTIMATES
by
duration
for ARI
(years):1 2 5 10 25 50 100 200 500 1000
5-min:0.398 0.472 0.549 0.6 0.657 0.693 0.724 0.749 0.774 0.789
10-min:0.636 0.755 0.879 0.96 1.05 1.1 1.15 1.19 1.22 1.24
15-min:0.794 0.949 1.11 1.21 1.33 1.4 1.45 1.5 1.54 1.56
30-min:1.09 1.31 1.58 1.76 1.97 2.1 2.23 2.33 2.45 2.53
60-min:1.36 1.65 2.03 2.29 2.62 2.85 3.07 3.27 3.52 3.69
2-hr:1.6 1.94 2.41 2.75 3.18 3.5 3.81 4.11 4.49 4.78
3-hr:1.71 2.08 2.59 2.96 3.44 3.81 4.17 4.53 4.99 5.34
6-hr:2.08 2.51 3.12 3.59 4.21 4.7 5.18 5.67 6.33 6.84
12-hr:2.47 2.99 3.73 4.32 5.12 5.76 6.42 7.1 8.05 8.81
24-hr:2.89 3.49 4.36 5.03 5.94 6.66 7.4 8.15 9.18 9.99
2-day:3.38 4.06 5.03 5.77 6.77 7.54 8.33 9.13 10.2 11.1
3-day:3.59 4.31 5.31 6.09 7.13 7.95 8.79 9.64 10.8 11.7
4-day:3.8 4.55 5.59 6.4 7.5 8.37 9.25 10.2 11.4 12.4
7-day:4.34 5.17 6.28 7.15 8.33 9.27 10.2 11.2 12.5 13.6
10-day:4.93 5.86 7.04 7.95 9.19 10.2 11.1 12.1 13.5 14.6
20-day:6.63 7.82 9.23 10.4 11.9 13.1 14.3 15.6 17.3 18.6
30-day:8.2 9.65 11.2 12.4 14 15.2 16.4 17.7 19.3 20.5
45-day:10.3 12.1 13.9 15.2 17 18.3 19.7 21 22.8 24.1
60-day:12.4 14.5 16.3 17.7 19.6 21 22.3 23.6 25.2 26.5
Date/time (GMT): Thu Oct 8 20:47:48 2020
pyRunTime: 0.0169880390167

APPENDIX F
Outlet Works Rating Curves

Total outlet discharge from the spillway system
Client:NCEM Date:10/1/2020
Project:Overtopping Study Engineer:T.Carter
Dam:Lucas Lake Dam Dam No.RANDO-027
Reservior Water
Level (RWS)
Elevation (ft)
Primary spillway
discharge (cfs)
Total discharge from the
spillway system (cfs)
521.0 0.0 0.0
521.5 124.9 124.9
522.0 353.4 353.4
522.5 649.2 649.2
523.0 999.6 999.6
523.5 1396.9 1396.9
524.0 1836.3 1836.3
524.5 2314.0 2314.0
525.0 2827.2 2827.2
525.5 3373.5 3373.5
526.0 3951.1 3951.1
526.5 4558.4 4558.4
527.0 5193.9 5193.9
527.5 5856.5 5856.5
528.0 6545.1 6545.1
528.5 7258.7 7258.7
529.0 7996.5 7996.5
529.5 8757.8 8757.8
530.0 9541.8 9541.8
530.5 10347.9 10347.9
531.0 11175.5 11175.5
531.5 12024.0 12024.0
532.0 12893.0 12893.0
532.5 13782.0 13782.0
533.0 14690.6 14690.6
533.5 15618.2 15618.2
534.0 16564.6 16564.6
534.5 17529.4 17529.4
535.0 18512.2 18512.2
535.5 19512.8 19512.8
536.0 20530.7 20530.7
536.5 21565.7 21565.7
537.0 22617.6 22617.6
537.5 23686.0 23686.0
538.0 24770.8 24770.8
538.5 25871.6 25871.6
539.0 26988.3 26988.3
539.5 28120.6 28120.6
540.0 29268.3 29268.3
540.5 30431.2 30431.2
541.0 31609.1 31609.1
541.5 32801.8 32801.8
542.0 34009.1 34009.1
542.5 35230.9 35230.9
543.0 36467.0 36467.0
0.0
5000.0
10000.0
15000.0
20000.0
25000.0
30000.0
35000.0
40000.0
515.0 520.0 525.0 530.0 535.0 540.0 545.0Total discharge from the spillway system (cfs)Reservior Water Level (RWS) Elevation (ft)
The whole spillway system rating curve (cfs)