Evaluation of CSO Control Alternatives in Small Communities Michael Sullivan Limno-Tech, Inc.

Evaluation of CSO Control Alternatives in

Small Communities

Michael SullivanLimno-Tech, Inc.

Evaluation of CSO Control Alternatives2

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


Most Widely Used CSO Controls

Rank LTCP Control Activity1 Sewer separation

2 Sewer rehabilitation

3 Retention basins

4 Disinfection

5 Primary sedimentation

6 Storage tunnels and conduits

7 Upgraded WWTP capacity

8 Outfall elimination


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.


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


Add Wastewater Treatment Capacity

Evaluation of CSO Control Alternatives


Increase POTW CapacityCity 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.


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


Downspout Extension and Redirection

Milwaukee Metropolitan Sewer District


Rain Gardens


Typical Basement Sump Pump


Rain Garden Solution:Downspout and Basement Sump

RedirectionSweetwater Alliance, Duluth, MN


Smoke Testing:Identify and Eliminate Area Drains



Inflow ReductionSouth 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


Inflow ReductionBurlington, 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.


3. 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


Sewer Separation



Sewer Separation: Onondaga County, NY

Tallman and Onondaga Avenue Areas

Sub Areas Acres

Taylor Street 10

Tallman Street West 12

Onondaga Avenue 1 15

Onondaga Avenue 2 16

53


Onondaga County, NYDetails

New sanitary sewers constructed.

Old sewers become storm sewer.

Cost is $90,000 per acre

70% funding from Corps of Engineers


Onondaga County, NYAdditional 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.


Onondaga County, NYDisruption 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.


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.


4. Storage FacilitiesMany 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


Off-Line StorageExcavation of Retention Basin

Massachusetts Water Resources Administration, MA


On-Site Storage - Flow Equalization Basin



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)


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 1985.Tannery pretreatment facility brought back on line in mid-1990s.New storage volume is 1.5 MGCost was $110,000 (7 cents per gallon)


CSO Technology References

Report to Congress on Impacts and Control of CSOs and SSOs

http://www.epa.gov/npdes/pubs/csossoRTC2004_AppendixL.pdf

EPA Municipal Support Division Fact Sheetswww.epa.gov/owm/mtb/mtbfact.htm

Rouge River National Wet Weather Demonstration Project (MI)www.wcdoe.org/rougeriver/

Columbus Water Works National Demonstration Program (GA)www.cwwga.org/NationalPrograms/Index.htm

http://www.epa.gov/npdes/pubs/csossoRTC2004_AppendixL.pdf

http://www.epa.gov/owm/mtb/mtbfact.htm

http://www.wcdoe.org/rougeriver/

http://www.cwwga.org/NationalPrograms/Index.htm


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


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?


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


CSO ControlWest 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)

Improvement Date Effect on CSOsBuilt relief sewer and

Swirl concentrator

1981 Increased storage

Partial treatment

POTW expansion 1985 Eliminated some CSOs

NW sewer separation 1986 Decreased CSS area

NW sewer separation 1988 Eliminated one CSO

SW sewer separation 1993 Decreased CSS area

POTW Expansion 1999 Added capacity: 2.5 MGD average, and 5.0 MGD maximum



CSO ControlSaltsburg 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.


CSO ControlSouth 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


CSO ControlBangor, 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)

Evaluation of CSO Control Alternatives in Small Communities Michael Sullivan Limno-Tech, Inc.

Documents

cso control policy

inflow control

cso discharge

available slide

small cso communities

outfall elimination

excess potw treatment

pumping capacity