Stormwater Infiltration and soil/groundwater contamination: A guide to the Construction Stormwater Permit requirements
The construction stormwater permit may prohibit infiltration practices on properties where existing contamination in groundwater or soil is present. The permit requires permittees proposing stormwater infiltration to analyze their specific site to determine if infiltration is appropriate. This page explains the minimum assessment required in order to demonstrate compliance with the permit at sites with potential or known soil and/or groundwater contamination.
Permit language (item 16.15)
"Permittees are prohibited from constructing infiltration systems where high levels of contaminants in soil or groundwater may be mobilized by the infiltrating stormwater. Permittees must either complete the MPCA's site screening assessment checklist or conduct their own assessment to determine the suitability for infiltration. The assessment must be retained with the SWPPP."
MPCA's screening assessment tool
- Access the MPCA's site screening assessment checklist: This is an Excel file
- Access the guidance: Screening assessment for contamination at potential stormwater infiltration sites: This page provides guidance for using MPCA's site screening checklist
- Access example screening assessments: This links to examples that utilize the above guidance, including the screening assessment
Guidance
Access guidance on Stormwater infiltration and contaminated soils and groundwater
For more information on how to determine if high levels of contamination exist at a site, link here.