1. Alternative Compliance for New Developments
NPDES Permit Provision C.3.g
“Alternative Compliance Based on Impracticability and Requiring Compensatory Mitigation”
Dan Cloak Environmental Consulting

2. Outline Key Limitations of C.3.g Options for applicants
Options for municipalities

3. Key Limitations C.3.g applies only to stormwater treatment
Site design must still minimize imperviousness
Source control BMPs still required
HMP requirements still apply
Applicant must demonstrate:
Impracticability of on-site treatment
Equivalent off-site treatment or other benefit
Municipality must document and report each project granted alternative compliance

4. Three Options for Applicants
Participate in a “Regional Stormwater Treatment Facility”
Demonstrate infeasibility on project site and implement compensatory mitigation on another site
Obtain an exemption based on certain project characteristics (stated in the permit)

5. Option 1: Regional Facility
See
For a discussion of regional stormwater ponds vs. on-site “rain gardens” in Fairfax County, VA.
Extended Detention Basin
Appropriate for drainage areas of 20 acres or more

6. Option 1: Regional Facility
Examples
Pond or playing field in a park
Existing lagoon or modified flood control basin
Advantages
No demonstration of infeasibility required
Facility may be in a different drainage area
Existing facilities can be used or modified
Possible savings in land, capital, and maintenance costs
Disadvantages
Must plan, locate, construct, and maintain
Must determine how applicants pay in and how much
See
For a discussion of regional stormwater ponds vs. on-site “rain gardens” in Fairfax County, VA.

7. Option 2: Alternative Site
Examples
Retrofit an existing parking lot
Fund pollutant remediation, habitat restoration, or other “equivalent water quality benefit”
Advantage
Avoid excessive costs or impracticability on difficult sites (e.g. hillside or 100% lot-line development)
Disadvantages
Must establish infeasibility of on-site treatment
Must establish that off-site benefit is equivalent
Design and mobilization costs to build two projects

8. Option 3: Exemption Examples (categories specified in Permit)
Development of a brownfield
Low and moderate income housing
Transit-village type development
Advantage
No compensatory mitigation required
Disadvantages
Categories are narrowly defined
Must demonstrate impracticability of on-site treatment
Must also demonstrate that alternative compliance would “unduly burden” the project financially

9. Two Options for Municipalities
Establish an Alternative Compliance Program
Define criteria for infeasibility and impracticability
“Impracticability” may include economic threshold
Submit for Water Board review and approval
“Interim” Alternative Compliance
Municipality may review project-by-project
Must show impracticability of on-site treatment
Must establish equivalent treatment within six months
“Equivalent water-quality benefit” projects that do not include treatment devices require Water Board approval