MPCA Infiltration Device - Pond Requirements

The use of stormwater infiltration has been a popular choice for stormwater management for many years. The benefits of infiltration include reducing overall run-off volume, reducing stormwater and channel run-off rates, and reducing pollutant loading.

However, infiltration can also create other issues, including groundwater contamination. Infiltration of stormwater (and the wastes it carries) may also invoke other environmental regulations.

The Minnesota Pollution Control Agency has incorporated requirements for the use of both infiltration devices and stormwater ponds used to manage industrial site runoff. These requirements include:

1. Industrial stormwater ponds and infiltration devices located in areas where high levels of contaminants exist in the soil or in the shallow aquifer, must not contribute to contaminant(s) spreading to a greater extent or rate. At any contamination site, a site analysis shall be conducted and a report filed with the SWPPP.

a. If industrial stormwater ponds and infiltration devices are found to be a contributor to contaminant increase or movement, the site must submit a plan to MPCA that describes how they will be reducing contaminants, redesigning, relocating, or eliminating the industrial stormwater ponds and infiltration devices, as needed, to eliminate the contribution to contaminant problems.

2. Industrial stormwater ponds and infiltration devices can not be used in any high risk karst area unless a professional geotechnical evaluation is conducted to ensure that they do not present a significant risk to groundwater.

a. If the industrial stormwater ponds and infiltration devices present a risk, appropriate measures, such as sealing or removal of the industrial stormwater ponds or infiltration devices, must be taken to eliminate or minimize the risk. Evaluations shall be documented with the SWPPP.

3. Use of industrial stormwater ponds and infiltration devices in vulnerable wellhead protection areas must be coordinated with local drinking water authorities and shall be designed to not adversely affect drinking water supplies. The facility must contact the appropriate local drinking water authorities and document coordination efforts with the SWPPP.

4. Facilities using any infiltration device defined as a “Class V injection well” shall contact the US EPA Region HQ to determine the need to register as a “Class V injection well”. Contacts and USEPA response need be documented with the SWPPP.

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