1. Detention Pond and Channel Stabilization for Bartholomew Park
Tanya Hoogerwerf, Sara Poindexter, Travis Wilson and David Kracman
December 13, 2001

2. Outline Watershed deliniation HEC-HMS network Pond design
Downstream channel improvements
System performance for design storms

3. Watershed Deliniation
2.2 acres P2
12.3 acres P1
7.5 acres

4. HEC-HMS Network

5. Pond Design Pond Width 150 ft Pond Length Side Slope 3:1
Spillway Elevation
6 ft
Spillway Length
30 ft
Orifice Plate Elevation
0 ft
Orifice Plate Area
1 ft2
Culvert Elevation
2 ft
Culvert Diameter

6. Downstream Channel Improvements
PARAMETERS
Channel width = 5 ft
Longitudinal slope = 0.1
Angle of repose = 40
Side Slope 2:1
25-year design flow = 30 cfs
RESULTS
d50 = 8 inches
d20 = 4 inches
d100 = 16 inches
Flow depth = 0.56 ft
Flow velocity = 10 ft/s

7. System Performance – 25-year Flood
Peak Inflow: 73.5 cfs
Peak Outflow: 33.2 cfs
Peak Storage: 3.2 ac-ft
Peak Elevation: 5.2 ft

8. System Performance – 100-yr Flood
Peak Inflow: cfs
Peak Outflow: cfs
Peak Storage: 4.0 ac-ft
Peak Elevation: 6.2 ft

9. Performance – Water Quality 2-year Return Period Storm
Calculated Detention Time of 9 hours
Below Normally Recommended Time
Solution – decrease low-flow orifice area
Possible health benefits from lower detention time?

10. Questions?