Selecting and Living with CSO Performance Measures

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Selecting and Living with CSO Performance Measures

• Gary W. Mercer, P.E.
• CDM
• Cambridge, Massachusetts

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Agenda

• CSO Policy
• Legal Agreement
• Performance Measures
• Who Selects?
• Types of Measures
• Comparison of Measures

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CSO Policy

• Demonstrative Approach requires the CSO program
  will meet the state water quality standards.
• Presumptive Approach presume compliance with
  water quality standards if
• No more than four to six discharges per year,
• Elimination or capture of eighty-five percent of
  the volume of pollutants concerned, or
• Elimination or capture of eighty-five percent of
  the mass of pollutants concerned

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Selection of CSO Program

• Most communities select their CSO program based
  on one or more of the following
• Affordability (UAA)
• Meeting water quality standards (No need for UAA)
• Combination of cost of program and
  cost-effectiveness. (UAA?)
• Perceived goal of 4 overflows per year (UAA?)

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Legal Agreement

• CSO Long Term Control Plan completed and approved
  by regulatory agencies. (Yeah!!!!!)
• Legal agreement to implement selected CSO
  program such as consent decree, court order, or
  administrative order.

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Performance Measures

• Contained in legal agreement
• Forms of Performance Measure are
• Project schedule
• per year expenditure
• Monitor and confirm performance of completed CSO
  facilities
• Monitoring instream and confirm compliance of WQS

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Attributes of Performance Measures

• Directly measurable
• Relevant measure to program
• Reportable to agencies and public
• spent per year, projects completed, system
  improvement measures, or water quality
  improvement

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Who Selects the Performance Measures?

• EPA or State agency
• Community can try, but often they only add
  additional requirements.

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Types of CSO Performance Measures

• Group 1 Project list and schedule
• Bid date, construction start, construction
  complete, and/or start of operation.
• Compliance is based on progress in construction
• Legal agreement includes statement that any
  remaining CSO discharges will not cause or
  contribute to water quality exceedences.

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Types of CSO Performance Measures

• Group 2 Expenditure per year
• Compliance is based on expenditure.
• Use if affordability based
• Legal agreement includes statement that any
  remaining CSO discharges will not cause or
  contribute to water quality exceedences.

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Types of CSO Performance Measures

• Group 3 Performance of completed CSO facilities
• Annual CSO volume
• Percent capture
• CSO overflows per year (max. or average)
• Maximize use of facilities flow and/or volume
• Compliance is at completion of project and after
  monitoring performance of CSO facilities
• Legal Agreement includes statement that any
  remaining CSO discharges will not cause or
  contribute to water quality exceedences.

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Types of CSO Performance Measures

• Group 4 Meet water quality goals (standards)
• bacteria reduction and/or improved dissolved
  oxygen
• Compliance is at completion of program and after
  monitoring instream water quality
• Legal agreement includes statement that any
  remaining CSO discharges will not cause or
  contribute to water quality exceedences.

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Comparison of PMs
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Comparison of PMs

• Group 1 (Project schedule) and Group 2 ( per
  year)
• Build and believe
• Group 3 (Facilities performance) and Group 4
  (Meet WQ Goals)
• Build and prove

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Comparisons of PMs

• For Groups 3 and 4
• Performance measured after construction
• Comparing predicted performance to actual
  performance
• Subject to accuracy of metering, models and
  analysis
• If facility not adequate, may/will need to build
  moreBUT.

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Comparison of PMs

• Ultimate goal of CSO program is CSO facility
  performance and achieving water quality goals.
• Either you know and solve the issue, or
• Stay blissful ignorant of issue