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

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

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

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)

Option 1: Regional Facility See http://www.co.fairfax.va.us/nvswcd/newsletter/regionalponds.htm 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

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 http://www.co.fairfax.va.us/nvswcd/newsletter/regionalponds.htm For a discussion of regional stormwater ponds vs. on-site “rain gardens” in Fairfax County, VA.

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

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

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