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EPAs CSO Policy

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CSOs are subject to NPDES permit program (including water quality based standards) CSOs are not subject to secondary treatment ... Federalism/10th Amendment ... – PowerPoint PPT presentation

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Title: EPAs CSO Policy


1
EPAs CSO Policy
  • Environmental Law I
  • Fall 2005

2
Whats Combined in a Combined Sewer System?
  • Sanitary waste
  • Pretreated industrial waste
  • Stormwater collecting in sewers

3
Where the Combined Sewers Are
750 out of 20,000 systems nationwide
4
How a CSO Happens
Feeder lines
Trunk or Interceptor
Sewer Plant
CSOs
River
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Where the Bflo CSOs are . . .
8
A view from the river
9
Primary Legal Handle for CSOs
  • CSOs are subject to NPDES permit program
    (including water quality based standards)
  • CSOs are not subject to secondary treatment
    requirements for POTWs
  • Primary screen out solids, disinfect
  • Secondary digest the sewage (activated sludge,
    e.g.)

10
Problems in CSO regulation
  • Most CSO fixes are extremely expensive
  • Unfunded mandates (a political and a legal
    problem)
  • Unfunded Mandates Act
  • Federalism/10th Amendment
  • Lapse of federal sewer grants and replacement
    with revolving loan fund
  • Passing burden to urban ratepayers

11
Current Solution EPAsCombined Sewer Overflow
Policy(33 USC sec. 1342(q))
  • Phased implementation considering a communitys
    financial capability
  • Guidance, not binding
  • Flexible and site-specific
  • Try to force localities and states to engage in
    coordinated planning

12
Short-Term/Long-Term Strategy
  • Short term (within 2 years) adopt the Nine
    Minimum Controls and document it
  • Develop a long-term plan based on adequate
    understanding of the sewer system and water body,
    local financial ability

13
Nine Minimum Controls (pt. 1)
  • Assure proper operation, regular maintenance
  • Maximize system storage capacity
  • Maximize flow to the POTW for treatment
  • No CSOs in dry weather

14
Nine Minimum Steps, pt. 2
  • Control solids and floatables in CSOs
  • Use pollution prevention
  • Give public notice of CSO occurrences, impacts
  • Monitor to characterize CSO impacts, efficacy of
    controls

15
Long Term Control Plan (1)
  • Characterization, monitoring, modeling of the CSS
  • for a range of storm events
  • N, location, frequency of overflows
  • volume, mass, concentration of pollutants
    discharged
  • impacts on designated uses of receiving waters

16
Characterizing the sewer system
  • Examine complete rainfall record for area
  • Evaluate flow variations in river
  • Correlate CSOs to receiving water conditions
  • Document overflows in relation to sensitive areas
    and pollution sources (can you move or relocate
    outfall?)

17
Monitoring of CSOs
  • Should be comprehensive and representative
  • Should include frequency, duration, flow rate,
    volume, pollutant concentration in CSOs
  • Also should include impact of CSOs on receiving
    waters

18
Uses of Modeling
  • EPA supports the proper and effective use of
    models, where appropriate
  • Sophistication of the model should relate to the
    complexity of the system and the information
    needed
  • Continuous simulation models using historical
    rainfall data are best

19
Consideration of alternatives
  • Zero overflows per year
  • 1 to 3 overflows/yr
  • 4-7 overflows/yr
  • 8-12 overflows/yr

20
Presumption vs. Demonstration
  • If it meets any of the following criteria, the
    controls are presumed adequate otherwise, you
    have to prove it

21
  • No more than 4-6 overflows per year, on average
  • System-wide average capture during storm events
    of 85 of the flow volume
  • Removes at least the mass of pollutants causing
    impairments

22
Cost-Performance Curves Finding the Knee of the
Curve
Cost
Pct Captured
23
What if too much stormwater gets to the treatment
plant?
  • Bypasses--40 CFR 122.41(m)
  • Unavoidable to prevent loss of life, personal
    injury, or severe property damage
  • No feasible alternative
  • Notice is given

24
Buffalos Long-Term Study
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Automated monitoring (Hydrolab Datasonde 4) All
10 sites, sample every 15 minutes
Analyze for conventional parameters (DO,
turbidity, pH, temperature, conductivity)
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Some control options
  • Complete separation
  • Storage (e.g., deep tunnel or retention basin)
  • Input reduction
  • Screen flotables

31
The land use dimension
32
An Alternative Approach to CSOs
  • Mr. FloatieMascot of People Opposing Outfall
    Pollution (P.O.O.P.), Vancouver, B.C.
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