Presentation on theme: "Evaluation of CSO Control Alternatives in Small Communities Michael Sullivan Limno-Tech, Inc."— Presentation transcript:
Evaluation of CSO Control Alternatives in Small Communities Michael Sullivan Limno-Tech, Inc.
Evaluation of CSO Control Alternatives 2 Elements of an LTCP for Small CSO Communities Required in CSO Control Policy: Consideration of sensitive areas Public participation Evaluation of CSO control alternatives Useful or likely to be required: Characterization (not necessarily monitoring and modeling Maximization of treatment at the POTW Post-construction compliance monitoring
Evaluation of CSO Control Alternatives 3 Most Widely Used CSO Controls RankLTCP Control Activity 1Sewer separation 2Sewer rehabilitation 3Retention basins 4Disinfection 5Primary sedimentation 6Storage tunnels and conduits 7Upgraded WWTP capacity 8Outfall elimination
Evaluation of CSO Control Alternatives 4 CSO Controls for Small Community Consideration 1.Maximization of treatment at the POTW. 2.Inflow control. 3.Sewer separation. 4.Storage. Emphasis placed on these controls, but there are many other types of controls available.
Evaluation of CSO Control Alternatives 5 1. Maximization of Treatment at the POTW Take advantage of existing infrastructure Increase conveyance and pumping capacity where excess POTW treatment capacity is available Increase POTW treatment capacity where conveyance is available
Build on Existing Infrastructure: Increase Pump Station Capacity Wilmington, DE Evaluation of CSO Control Alternatives 6
Add Wastewater Treatment Capacity Evaluation of CSO Control Alternatives
8 Increase POTW Capacity City of Frankfort, KY (pop 27,750) In Frankfort the 2001 expansion increased the POTW capacity from a 6.6 MGD facility to a 9.9 MGD facility.
Evaluation of CSO Control Alternatives 9 2. Inflow Reduction Various techniques used to reduce the amount of water that enters a CSS through: Roof leaders Area drains Foundations drains Basement sump pumps
Find and Eliminate Downspouts Evaluation of CSO Control Alternatives
Downspout Extension and Redirection Milwaukee Metropolitan Sewer District Evaluation of CSO Control Alternatives
Rain Gardens Evaluation of CSO Control Alternatives
Typical Basement Sump Pump Evaluation of CSO Control Alternatives
Rain Garden Solution: Downspout and Basement Sump Redirection Sweetwater Alliance, Duluth, MN Evaluation of CSO Control Alternatives
Smoke Testing: Identify and Eliminate Area Drains Evaluation of CSO Control Alternatives
16 Inflow Reduction South Portland, ME (Pop: 23,200) CSS covers 5,250 acres Surveyed 6,000 residential buildings. Found 380 roof leaders connected to CSS. Notified property owners and established rebate program: $75 for roof leader diversion* $400 for basement sump pump diversion* Achieved substantial reduction in CSO discharge for relatively low cost. * 1995 dollars
Evaluation of CSO Control Alternatives 17 Inflow Reduction Burlington, IA (Pop 26,800) Inspected 1,300 manholes (GPS opportunity). Smoke testing on 300,000 lf sewer line. Surveyed 4,500 homes Disconnected all but 50 of 1,400 roof leaders.
Evaluation of CSO Control Alternatives Sewer Separation A widely used CSO control – especially in small communities. Can be expensive and disruptive. Often implemented with other projects – road work, utility work, and redevelopment. Solves CSO problem, but adds to storm water problem.
Sewer Separation Evaluation of CSO Control Alternatives 19
Sewer Separation Evaluation of CSO Control Alternatives
21 Sewer Separation: Onondaga County, NY Tallman and Onondaga Avenue Areas Sub Areas Acres Taylor Street10 Tallman Street West12 Onondaga Avenue 115 Onondaga Avenue
Evaluation of CSO Control Alternatives 22 Onondaga County, NY Details New sanitary sewers constructed. Old sewers become storm sewer. Cost is $90,000 per acre 70% funding from Corps of Engineers
Evaluation of CSO Control Alternatives 23 Onondaga County, NY Additional Improvements Replacing sewer laterals from street to curb line. Making spot repairs to existing combined sewer. Replacing active lead or galvanized iron water lines from water main to curb stop. Gas utility replacing gas main in some portions of work areas.
Evaluation of CSO Control Alternatives 24 Onondaga County, NY Disruption Considerations Development of traffic plan. Construction done during normal work hours. Advance notification of water service disruption and alternative water source provided. Minimization of gas service interruptions.
Evaluation of CSO Control Alternatives 25 Sewer Separation Example Randolph, VT (Pop: 2,270) Separated 44 of 52 catch basins. Cost to date is $2.7M 25% State grant 50% State revolving fund loan 25% City of Randolph CSOs reduced but not eliminated. Achieving full separation is difficult. Planning to spend another $0.5M.
Evaluation of CSO Control Alternatives Storage Facilities Many possibilities for small communities In-line storage—oversized conduits and regulators; in-line tanks; parallel relief sewers. Off-line storage—retention basins/tunnels to store wet weather flow for subsequent treatment. On-site storage / flow equalization—storage at WWTP to manage excess wet weather flow.
In-Line Storage: Inflatable Dam Evaluation of CSO Control Alternatives
Off-Line Storage Excavation of Retention Basin Massachusetts Water Resources Administration, MA Evaluation of CSO Control Alternatives
On-Site Storage - Flow Equalization Basin Evaluation of CSO Control Alternatives
30 On-Site Storage Example Oakland, ME (Pop: 6,000) Restoration of unused flow equalization basin: Had sufficient conveyance capacity. Needed additional wet weather capacity. Restored unused flow equalization basin from closed textile mill. New storage volume is 0.2 MG Cost was $27,600 (14 cents per gallon)
Evaluation of CSO Control Alternatives 31 On-Site Storage Example South Paris, ME (Pop: 2,237) Restoration of unused pretreatment facility: Wastewater treatment system designed with two pretreatment facilities – tannery and cannery. Tannery closed in Tannery pretreatment facility brought back on line in mid-1990s. New storage volume is 1.5 MG Cost was $110,000 (7 cents per gallon)
Evaluation of CSO Control Alternatives 32 CSO Technology References Report to Congress on Impacts and Control of CSOs and SSOs EPA Municipal Support Division Fact Sheets Rouge River National Wet Weather Demonstration Project (MI) Columbus Water Works National Demonstration Program (GA)
Evaluation of CSO Control Alternatives 33 Screening and Evaluation of CSO Controls The screening and evaluation of controls should: Include WQ considerations Consider site specific control needs Address performance of control technologies Describe implementation issues Explain reasons for selecting CSO control alternatives Explain reasons for rejecting other controls Note: Looking for logical decision-making process
Evaluation of CSO Control Alternatives 34 Selecting the Best CSO Control Alternatives Will water quality and designated uses be protected? Have sensitive areas been considered? Has a reasonable range of CSO control alternatives been considered? Has public input been obtained and used? Has financial capability been assessed?
Evaluation of CSO Control Alternatives 35 Final Selection of CSO Control Alternatives Should be based on: Control priorities Site specific conditions Protection of WQS and designated uses Public input Cost-effectiveness of controls Financial capability Other considerations
Evaluation of CSO Control Alternatives 36 CSO Control West Lafayette, IN (Pop 28,900) The 20 Year plan for CSO control that began in mid-1990s includes: An $18 million upgrade to the POTW A $2.2 million foundation drain disconnect program in the BarBarry neighborhood (1999) Construction of the $2.3 million North River Road lift station (1999). The $1.9 million rehabilitation of the Happy Hollow interceptor (2001). Construction of the $5.9 million wet weather treatment facility to reduce CSO impacts on the Wabash River (2003).
CSO Control: Auburn, IN (Pop 12,000) ImprovementDateEffect on CSOs Built relief sewer and Swirl concentrator 1981Increased storage Partial treatment POTW expansion1985Eliminated some CSOs NW sewer separation1986Decreased CSS area NW sewer separation1988Eliminated one CSO SW sewer separation1993Decreased CSS area POTW Expansion1999Added capacity: 2.5 MGD average, and 5.0 MGD maximum Evaluation of CSO Control Alternatives
38 CSO Control Saltsburg Borough, PA (Pop. 955) Small population and limited budget required emphasis on NMCs: Proper O&M of existing sewer system. Installed baffles to control floatables in catch basins. Notification signs at CSOs Community bulletin board for education abut CSOs. Limited monitoring of CSO volume and freq.
Evaluation of CSO Control Alternatives 39 CSO Control South Portland, ME (Pop: 23,200) Achieved 90 percent reduction in CSO volume Wet weather primary capacity expanded from 12 mgd to 56 mgd Adjusted weir heights Upgraded pump stations Inflow reduction (roof leaders and sump pumps) Select sewer separation Eliminated 25 of 30 CSO outfalls
Evaluation of CSO Control Alternatives 40 CSO Control Bangor, ME (Pop: 31,500) Sewer separation – 23 projects – $6.3M. Increased primary treatment by 13 MGD. Eliminated 33% of CSO outfalls. Built 1.2 MG off-line storage beneath parking lot for $2.3M ($1.92 per gallon)