Dodge County Drainage Board

Transcription

1 Dodge County Drainage Board Drainage District 1 ATCP Specifications November 24, 2016 Prepared By: DesignTech Engineering, LLC P.O. Box 293 Beaver Dam, Wisconsin Phone: (920) dan@dteusa.com Project No. dd01-16

2 Dodge County Drainage District 1 District Specifications Introduction District 1 was organized circa 1919 as Town of Oak Grove Drain No. 1. Its drainage basin is unique in that much of what was once farm land is now the Dodge County Airport. In addition to the runways and taxiways of the airport, the basin includes about one half of a mile of N. Main Street/State 26 with high density residential housing, rooftops, sidewalks and driveways and the parking lot of the Clearview Health facility. Unfortunately, the surface water runoff generated by all of these impervious surfaces flows through the District 1 main tile. The District consists of 2 parts, the main tile which handles both the urban runoff and the individual land owner private tile systems, and the outlet which is a navigable waterway. There are no benefitted lands along the waterway southerly of County W. The waterway is a part of the district solely to maintain a viable outlet for the tile system. Flow Computations Appendix A attached hereto contains flow calculations using the methods outlined in ATCP 48 Appendix A. The flows generated using the USGS regression equations in "Flood-Frequency Characteristics of Wisconsin Streams", Walker & Krug, 2003, hereinafter regression equations are far too high. In all likelihood, the reason for the high flows is that the equations are based on an unregulated stream. However in this case, the stream is highly regulated by numerous undersized culverts on farm crossings and public roadways. Conversely, the base flows generated by 1 are far too low. The exception is the base flow for the tile which is for all intents and purposes, zero. Consequently, base flow for the stream was established by members observations that there is always at least 6 of flow in the channel near County S (Sta ). The resulting flow is 2.14 cfs. Base flow for the tile is zero. Q 10 for the stream was set as full channel (existing conditions) at Sta which is 190 cfs. Q 10 for the tile was set by assuming a hydraulic grade line = ground surface at Sta and top of pipe at Sta (This stretch is the outlet and is at an extremely flat grade) The resulting flow is 45 cfs. Page 1 of 10

3 Appendix A Flow Calculations Flood Frequency Characteristics of Wisconsin Streams Dodge Co. Drainage District 1 Design Notes Hydrologic Area County S A = 6,926 Ac / 640 = sq. mi. ST = 270 Ac / 6,926 Ac = 3.9 (actual) L = 34,112 ft. 10% = 3,411 ft, % = 28,995 ft, End Tile A = 828 Ac / 640 = 1.45 sq. mi. ST = 0 L = 11,985 ft. 10% = 1,198.5 ft, % = 10,187 ft, S = , = ft/mi 5,280 S = ,187 1,198. = ft/mi Nehls Crossing A = 6,487 Ac / 640 = sq. mi. ST = 261 Ac / 6,487 Ac = 4.0 (actual) L = 29,417 ft. 10% = 2,942 ft, % = 25,004 ft, Beg. Tile A = 200 Ac / 640 = 0.31 sq. mi. ST = 0 L = 4,358 ft. 10% = ,901.5 ft 85% = 3,704 ft, S = ,004 2,942 = ft/mi 5,280 S = , = ft/mi County W A = 6,448 Ac / 640 = sq. mi. ST = 261 Ac / 5,518 Ac = 4.7 (actual) L = 27,547 ft. 10% = 2,755 ft, % = 23,415 ft, S = ,415 2,755 = ft/mi 5,280 Page 2 of 10

4 Area 5 Flood Frequency Equations for Streams in Wisconsin End County S Area = sq. mi. = ft/mi STorage = 4.9 percent + 1 Q2 = 170 CFS Q5 = 216 " Q10 = 265 " Q25 = 328 " Q50 = 375 " Q100 = 422 " From "Flood-Frequency Characteristics of Wisconsin Streams", Walker & Krug, 2003 Area 5 Flood Frequency Equations for Streams in Wisconsin Nehls Crossing Area = sq. mi. = ft/mi STorage = 5 percent + 1 Q2 = 164 CFS Q5 = 210 " Q10 = 258 " Q25 = 320 " Q50 = 365 " Q100 = 412 " From "Flood-Frequency Characteristics of Wisconsin Streams", Walker & Krug, 2003 Area 5 Flood Frequency Equations for Streams in Wisconsin County W Area = sq. mi. = ft/mi STorage = 5.7 percent + 1 Q2 = 151 CFS Q5 = 191 " Q10 = 234 " Q25 = 289 " Q50 = 329 " Q100 = 370 " From "Flood-Frequency Characteristics of Wisconsin Streams", Walker & Krug, 2003 Page 3 of 10

5 Area 5 Flood Frequency Equations for Streams in Wisconsin End District Tile Area = 1.45 sq. mi. = 37 ft/mi STorage = 1 percent + 1 Q2 = 62 CFS Q5 = 103 " Q10 = 133 " Q25 = 173 " Q50 = 202 " Q100 = 232 " From "Flood-Frequency Characteristics of Wisconsin Streams", Walker & Krug, 2003 Area 5 Flood Frequency Equations for Streams in Wisconsin Begin District Tile Area = 0.31 sq. mi. = ft/mi STorage = 1 percent + 1 Q2 = 17 CFS Q5 = 31 " Q10 = 41 " Q25 = 53 " Q50 = 62 " Q100 = 72 " From "Flood-Frequency Characteristics of Wisconsin Streams", Walker & Krug, 2003 Page 4 of 10

6 Base Flow Determination Pratt Creek joins Beaver Dam River between Lowell and Reeseville. Next downstream gaging station is CRAWFISH RIVER AT MILFORD, WI. Data obtained from Water Resources Data, Wisconsin Water Year 2005, USGS Water-Data Report WI Drainage area = 762 mi 2. For the years : 10% exceeds 1,100 cfs => cfs/mi 2 50% exceeds 200 cfs => cfs/mi 2 90% exceeds 41 cfs => cfs/mi 2 ( Base Flow ) Determine all 3 values at the same points above for Flood-Frequency Characteristics End County S, Area = mi 2 10% = 16 cfs 50% = 3 cfs 90% = 1 cfs This value is unrealistically low Nehls Crossing, Area = mi 2 10% = 15 cfs 50% = 3 cfs 90% = 1 cfs This value is unrealistically low County W Area = mi 2 10% = 15 cfs 50% = 3 cfs 90% = 1 cfs This value is unrealistically low End district tile Area = 1.45 mi 2 10% = 2 cfs 50% = 0.4 cfs 90% = 0.1 cfs This value, essentially zero, is realistic Begin district tile Area = 0.31 mi 2 10% = 0.45 cfs 50% = 0.10 cfs 90% = 0.02 cfs This value, essentially zero, is realistic Page 5 of 10

7 Sta Mannings Coefficient ft Left Side Right Side 3.00 ft cfs 43.9 ft² Wetted Perimeter ft ft 1.64 ft Critical ft/ft 1.51 ft/s Head 0.04 ft 3.74 ft Froude Number 0.18 Sta Mannings Coefficient ft Left Side 0.50 V : H Right Side 0.50 V : H 6.00 ft cfs 67.5 ft² Wetted Perimeter ft ft 1.88 ft Critical ft/ft 1.80 ft/s Head 0.05 ft 4.55 ft Froude Number 0.19 Sta Mannings Coefficient ft Left Side 1.06 V : H Right Side 1.06 V : H 6.40 ft cfs 95.0 ft² Wetted Perimeter ft ft 2.82 ft Critical ft/ft 2.26 ft/s Head 0.08 ft 7.28 ft Froude Number 0.18 Sta Note: Use this full channel flow for Q10 Mannings Coefficient ft Left Side 1.11 V : H Right Side 1.11 V : H 9.30 ft cfs 87.1 ft² Wetted Perimeter ft ft 2.18 ft Critical ft/ft 2.18 ft/s Head 0.07 ft 6.02 ft Froude Number 0.18 Page 6 of 10

8 Base flow determination assuming 6 flow depth at Sta Mannings Coefficient ft Left Side Right Side 6.70 ft 2.14 cfs 3.9 ft² Wetted Perimeter 9.29 ft 9.09 ft 0.14 ft Critical ft/ft 0.54 ft/s Head 4.55e-3 ft 0.50 ft Froude Number 0.14 Base flow at Sta proposed channel Channel Left Side Right Side 3.00 ft 2.14 cfs 0.69 ft 3.2 ft² Wetted Perimeter 6.58 ft 6.30 ft 0.24 ft Critical ft/ft 0.67 ft/s Head 0.01 ft 0.70 ft Froude Number 0.16 Q10 at Sta Note: Flow depth above banks Channel Left Side Right Side 3.00 ft cfs 5.49 ft 88.5 ft² Wetted Perimeter ft ft 2.74 ft Critical ft/ft 2.15 ft/s Head 0.07 ft 5.56 ft Froude Number 0.22 Base flow at Sta Channel Left Side 0.50 V : H Right Side 0.50 V : H 6.00 ft 2.14 cfs 0.50 ft 3.5 ft² Wetted Perimeter 8.24 ft 8.01 ft 0.16 ft Critical ft/ft 0.61 ft/s Head 0.01 ft 0.51 ft Froude Number 0.16 Page 7 of 10

9 Q10 at Sta Note: Flow depth above banks Channel Left Side 0.50 V : H Right Side 0.50 V : H 6.00 ft cfs 5.23 ft 86.2 ft² Wetted Perimeter ft ft 2.40 ft Critical ft/ft 2.20 ft/s Head 0.08 ft 5.31 ft Froude Number 0.22 Base flow at Sta Channel Left Side 1.06 V : H Right Side 1.06 V : H 6.39 ft 2.14 cfs 0.50 ft 3.4 ft² Wetted Perimeter 7.76 ft 7.33 ft 0.15 ft Critical ft/ft 0.62 ft/s Head 0.01 ft 0.51 ft Froude Number 0.16 Q10 at Sta Channel Left Side 1.06 V : H Right Side 1.06 V : H 6.39 ft cfs 6.39 ft 79.4 ft² Wetted Perimeter ft ft 2.63 ft Critical ft/ft 2.39 ft/s Head 0.09 ft 6.48 ft Froude Number 0.20 Base flow at Sta Channel Left Side 1.11 V : H Right Side 1.11 V : H 9.30 ft 2.14 cfs 0.40 ft 3.8 ft² Wetted Perimeter ft ft 0.12 ft Critical ft/ft 0.56 ft/s Head 4.8e-3 ft 0.40 ft Froude Number 0.16 Page 8 of 10

10 Q10 at Sta Channel Left Side 1.11 V : H Right Side 1.11 V : H 9.30 ft cfs 5.58 ft 79.8 ft² Wetted Perimeter ft ft 2.18 ft Critical ft/ft 2.38 ft/s Head 0.09 ft 5.67 ft Froude Number outfall surcharged to ground level at Sta pipe full at outfall Worksheet Pressure Pipe - 1 Flow Element Pressure Pipe Hazen-Williams Formula Pressure at psi Pressure at psi Elevation at ft Elevation at ft Length 2, ft C Coefficient Diameter 36 in Headloss Energy Grade at 1 Energy Grade at 2 Hydraulic Grade at 1 Hydraulic Grade at 2 Wetted Perimeter Head Friction cfs 7.42 ft ft ft ft ft 7.1 ft² 9.42 ft 6.43 ft/s 0.64 ft ft/ft 45 cfs at Sta Worksheet Circular Channel - 1 Flow Element Circular Channel Channel Mannings Coefficient ft/ft Diameter 36 in cfs 2.75 ft 6.8 ft² Wetted Perimeter 7.66 ft 1.66 ft 2.19 ft Percent Full 91.6 % Critical ft/ft 6.63 ft/s Head 0.68 ft 3.43 ft Froude Number 0.58 Maximum cfs Full cfs Full ft/ft Sta to Sta Determine upstream HGL (surcharged line) Worksheet Pressure Pipe - 2 Flow Element Pressure Pipe Hazen-Williams Formula Elevation at 1 Pressure at psi Pressure at psi Elevation at ft Length 1, ft C Coefficient Diameter 36 in cfs Elevation at 1 Headloss Energy Grade at 1 Energy Grade at 2 Hydraulic Grade at 1 Hydraulic Grade at 2 Wetted Perimeter Head ft 2.96 ft ft ft ft ft 7.1 ft² 9.42 ft 6.37 ft/s 0.63 ft Page 9 of 10

11 Friction ft/ft Determine HGL at Sta Worksheet Pressure Pipe - 2 Flow Element Pressure Pipe Hazen-Williams Formula Elevation at 1 Full Full cfs ft/ft Supercritical Pressure at psi Pressure at psi Elevation at ft Length ft C Coefficient Diameter 36 in cfs Elevation at 1 Headloss Energy Grade at 1 Energy Grade at 2 Hydraulic Grade at 1 Hydraulic Grade at 2 Wetted Perimeter Head Friction ft 0.66 ft ft ft ft ft 7.1 ft² 9.42 ft 6.37 ft/s 0.63 ft ft/ft Determine depth of flow Sta to Sta Worksheet Circular Channel - 2 Flow Element Circular Channel Channel Mannings Coefficient ft/ft Diameter 36 in cfs 1.80 ft 4.4 ft² Wetted Perimeter 5.31 ft 2.94 ft 2.19 ft Percent Full 60.0 % Critical ft/ft ft/s Head 1.61 ft 3.41 ft Froude Number 1.46 Maximum cfs Page 10 of 10

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