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A Better Partnership


Sep 2012
September 25, 2012

Venting Groundwater Laws Are More User Friendly

Amendments to Part 201, which were signed into law this summer, make it possible to avoid response actions that don’t really benefit the environment. But make no mistake, if there is a real-world need for a response to potential contamination, the new law will require it.

Governor Snyder signed the amendments, known as Public Act 190 of 2012 (Senate Bill 1090), into law in June. Basically, they do four important things:
  • Rescind the Groundwater-Surface Water Interface (GSI) rule (R299.5616 of the Michigan Administrative Code) 
  • Create more flexibility and options to address venting groundwater
  • Eliminate certain constraints and burdens on response actions
  • Allow for a more realistic evaluation of whether or not clean-up actions are necessary to protect surface water.

Ecological demonstrations and modeling demonstrations are new methods that may be used to show compliance where designated uses are not impaired and surface water quality criteria are not exceeded due to the venting plume.  Other provisions reinforce and enhance the use of surface water quality variances, mixing zones, site-specific criteria and biological criteria.

Groundwater entering storm sewers is addressed by moving the point of compliance to the outfall to surface water instead of upland wells near any storm sewer, and mixing zones may be used.  Illicit Discharge ordinances will continue to apply in the communities that have them, but this Act is still available for the Part 201 aspects of that venting.

The types and amount of data used to evaluate venting groundwater is tempered to counter demands by the Michigan Department of Environmental Quality (MDEQ) for excessive data to support GSI conclusions.

MDEQ must approve many, but not all, response actions taken under the Act. Generally, investigative actions and actions based on upland compliance points and generic GSI criteria can be taken without MDEQ approval.  The  provision on ,which actions must be approved by MDEQ are somewhat complex and should be examined in detail.

The Act continues the requirement that if a person is implementing GSI response activity and determines that acute criteria are exceeded, then that person must notify the MDEQ and take action. The Act also continues the availability of a Technical Impracticability Waiver where a person has controlled the source but cannot achieve compliance with the applicable GSI criteria.

A new de minimis provision is created so that GSI response actions, other than the data gathering, will not be required if the mass and flow rates support a conclusion that the venting contamination has no effect or only a de minimis effect on surface water.  In this regard, the MDEQ issued a new policy for mercury in venting groundwater that uses the higher (vs. the other extremely low) level of detection analytical method to determine the presence of mercury and to trigger further response action.  The policy is based on the fact that nearly all of the mercury entering the environment in Michigan is from airborne deposition and that an extremely small amount is present in surface water due to venting groundwater.

The Act has provisions that give it retroactive effect, including situations where there are pre-existing judgments, consent judgments, orders, consent orders and agreements with the MDEQ.  There also are provisions which include clarifications and revisions to the definition of “surface water.”

The regulation of the GSI was not necessarily made simpler by the Act, but the tools are now available to avoid unnecessary response actions. For further information, contact Michael Robinson at 616.752.2128 or

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