HomeMy WebLinkAboutDivision_St_SWU_Presentation_11-11-2010City of Oshkosh
November 11, 2010
Division Street Watershed Stormwater
Flooding Analysis
Overview
•Watershed Overview
•Existing Conditions
•Initial Alternatives
•Alternative Evaluation
•Final Alternatives
•Discussion/Questions
•Watershed Overview
•Existing Conditions
•Initial Alternatives
•Alternative Evaluation
•Final Alternatives
•Discussion/Questions
Watershed Overview
•Watershed evaluated as part of
the Streets CIP storm sewer
modeling
•Construction on several streets
occurred in 2010
–Merrill Street, Prospect Avenue,
Saratoga Avenue, Vacated
Railroad Right-of-Way
•Construction within watershed in
5-year CIP
–Church Avenue
–Central Street
–Parkway Avenue
–Ida Avenue
–City Hall Parking Lot
•Watershed evaluated as part of
the Streets CIP storm sewer
modeling
•Construction on several streets
occurred in 2010
–Merrill Street, Prospect Avenue,
Saratoga Avenue, Vacated
Railroad Right-of-Way
•Construction within watershed in
5-year CIP
–Church Avenue
–Central Street
–Parkway Avenue
–Ida Avenue
–City Hall Parking Lot
Watershed Overview
•Located in downtown Oshkosh
•Watershed area = 200 acres
•Includes City Hall, City Center, Jackson Street from
Church Avenue to Fox River
•Complex storm sewer system
•Impacted by Fox River water surface elevation
•High point is in middle of watershed (along Church
Avenue)
•Located in downtown Oshkosh
•Watershed area = 200 acres
•Includes City Hall, City Center, Jackson Street from
Church Avenue to Fox River
•Complex storm sewer system
•Impacted by Fox River water surface elevation
•High point is in middle of watershed (along Church
Avenue)
Existing Conditions
Worst Flooding Locations:
1.Pearl Avenue
2.Central Street & Frederick
Street low-points
3.Intersection of Melvin Avenue
and Frederick Street
4.Merrill Street low-point
between Saratoga Avenue and
Prospect Avenue
3
4
2
2
2
Worst Flooding Locations:
1.Pearl Avenue
2.Central Street & Frederick
Street low-points
3.Intersection of Melvin Avenue
and Frederick Street
4.Merrill Street low-point
between Saratoga Avenue and
Prospect Avenue
1
1
2
2
Initial Alternatives
•15 alternatives considered
•Aspects included:
–Improvements to existing storm sewers
–New storm sewers
–Above ground detention basins
–Underground storage
•15 alternatives considered
•Aspects included:
–Improvements to existing storm sewers
–New storm sewers
–Above ground detention basins
–Underground storage
Alternative Evaluation
•Alternatives were evaluated based on:
–Elimination of flooding in 10-year storm event
–Reduction in flood elevation & duration in 25-year storm event
–Feasibility of construction
–Construction cost
–Potential for contaminated soils
•Initial evaluation selected four alternatives
–Alternative 12 –Small underground storage
–Alternative 13 –Small detention basin
–Alternative 14 –Large underground storage
–Alternative 15 –Jackson Street box culvert
•Alternatives were evaluated based on:
–Elimination of flooding in 10-year storm event
–Reduction in flood elevation & duration in 25-year storm event
–Feasibility of construction
–Construction cost
–Potential for contaminated soils
•Initial evaluation selected four alternatives
–Alternative 12 –Small underground storage
–Alternative 13 –Small detention basin
–Alternative 14 –Large underground storage
–Alternative 15 –Jackson Street box culvert
Alternative Evaluation
•Further Evaluation of Alternatives
–Alternative 12 eliminated
•Other alternatives provided greater flood reduction
–Alternative 13 eliminated
•Acquisition of 13 houses required
•Other alternatives provided greater flood reduction
Final Alternatives
•Alternative 14
–Underground Storage at
City Hall
–Outlet from underground
storage to Jackson Street
–Mainline storm sewer on:
•Central Street (Box Culvert)
•Division Street (Circular)
–Storm sewer
improvements on other
streets
•Alternative 14
–Underground Storage at
City Hall
–Outlet from underground
storage to Jackson Street
–Mainline storm sewer on:
•Central Street (Box Culvert)
•Division Street (Circular)
–Storm sewer
improvements on other
streets
Final Alternatives
•Alternative 15
–Mainline storm sewer on:
•Jackson Street (Box Culvert)
•City Hall Parking Lot (Box
Culvert)
•Central Street (Box Culvert)
•Division Street (Circular)
–Storm sewer improvements
on other streets
•Alternative 15
–Mainline storm sewer on:
•Jackson Street (Box Culvert)
•City Hall Parking Lot (Box
Culvert)
•Central Street (Box Culvert)
•Division Street (Circular)
–Storm sewer improvements
on other streets
Final Alternatives
Final Alternatives
•Alternative 14 and 15 Comparison
–Reduction in flood elevation (10-year & 25-year storm events)
•Similar level of control
–Reduction in flood duration (25-year storm event)
•Similar level of control
–Feasibility of construction
•Alternative 14 –Impacts to parking at City Hall during construction
•Alternative 14 –Concerns with on-going maintenance
•Alternative 15 –Difficulties in constructing box culvert on Jackson Street
–Construction cost estimates
•Similar cost –Approximately $8 million for watershed-wide improvements
•Cost includes estimate for pipe and structures
•Costs do not include removal of contaminated soils
•Further evaluation of cost estimates are on -going
–Potential for contaminated soils
•Alternative 15 –Contaminated soils likely on Jackson Street
•Alternative 14 and 15 Comparison
–Reduction in flood elevation (10-year & 25-year storm events)
•Similar level of control
–Reduction in flood duration (25-year storm event)
•Similar level of control
–Feasibility of construction
•Alternative 14 –Impacts to parking at City Hall during construction
•Alternative 14 –Concerns with on-going maintenance
•Alternative 15 –Difficulties in constructing box culvert on Jackson Street
–Construction cost estimates
•Similar cost –Approximately $8 million for watershed-wide improvements
•Cost includes estimate for pipe and structures
•Costs do not include removal of contaminated soils
•Further evaluation of cost estimates are on -going
–Potential for contaminated soils
•Alternative 15 –Contaminated soils likely on Jackson Street
Discussion/Questions