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Contaminated Lands Environmental Action Network (CLEAN)

Managing Properties with Residual Contamination

Continuing Obligations to Protect Public Health and the Environment


What is Residual Contamination?

Wisconsin, like most states, allows some residual contamination to remain after a cleanup of contaminated soil or groundwater. Residual contamination means that some contamination remained above state standards after an environmental cleanup was completed and approved.

What is a Continuing Obligation?

When the state approves a cleanup with residual contamination it ensures long-term protection of public health and the environment in accordance with s. 292.12(2), Wis. Stats. [exit DNR] and other laws. The state does this by establishing continuing obligations in the state’s cleanup approval document, the “closure” letter. It is common for approved cleanups to have continuing obligations because Wisconsin generally does not require removal of all contamination.

Continuing obligations are certain actions for which property owners are legally responsible. They still apply after a property is sold - each new owner becomes responsible for them. The state provides notice to the public by adding the property and related continuing obligation information to a database on the Internet established in accordance with s. 292.12(3), Wis. Stats [exit DNR]. Continuing obligations are sometimes called "environmental land use controls" or "institutional controls."

The two most common continuing obligations are:

  1. Proper management of contaminated soil if it is excavated, and
  2. Obtaining approval for construction of water supply wells.

Other property-specific obligations may include:

  • keeping clean soil and vegetation over contaminated soil;
  • keeping a “cap” of pavement over contaminated soil or groundwater;
  • operating and maintaining a vapor venting system; or
  • notifying the state if a structural impediment (e.g. building) that restricted the cleanup is removed. The owner may then need to conduct additional state-approved environmental work.

Property owners with property-specific obligations must obtain the state’s permission before changing the portion of the property where these requirements apply.

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How to Comply with Continuing Obligations

Requirements for all properties with residual contamination

  1. If owners or occupants disturb residual contamination, they are responsible for proper sampling, handling and treatment or disposal of the contamination. For example, if they dig up contaminated soil they must treat or dispose of it legally. This is generally done with the assistance of a private environmental consultant.
  2. The property owner must obtain prior approval from DNR to construct or reconstruct a water supply well, if such work is planned. This approval ensures that the well will be properly constructed to protect it from the residual contamination. Well drillers may assist property owners in completing the application for this approval (GIS Registry Site Well Approval Application Form 3300-254).
  3. Some properties have additional requirements. There is a property-specific continuing obligation if:
    • the state’s closure letter requires monitoring or maintenance of specified physical conditions, or requires written state approval before changing specified physical or land use conditions; or
    • the state’s closure letter was written before June, 2006 and requires a deed restriction. In this case the continuing obligation is defined in the deed restriction.

When would the state apply a property-specific continuing obligation due to residual contamination?

  • When the state determines that the nature of the residual contamination requires installation and maintenance of:
    • a passive protective barrier such as pavement over a contaminated area, or
    • an active venting system to prevent volatile contaminants from entering a structure.
  • When a structural impediment restricted full investigation or cleanup of the contamination and the state requires more action if the impediment is removed. One example is completing an investigation of contaminated soil after a building that had restricted sampling under the foundation is demolished.
  • When the state imposed other limits to ensure appropriate use of the property. For example, the owner may be required to complete additional cleanup if the land use changes from industrial to residential or commercial.

What are the requirements for owners with property-specific continuing obligations?

The property owner must do the following, unless this responsibility has been contractually accepted by someone else:

  1. Periodically inspect the physical conditions specified in the closure letter, maintain the conditions of the continuing obligations and record these maintenance activities; and
  2. Obtain prior written approval from the state before changing the physical conditions if there is a property-specific continuing obligation. (This pre-approval does not apply to a general requirement to properly handle contaminated soil, which may be done under the guidance of a private environmental consultant.)

Requirements for groundwater monitoring wells that need to be abandoned

Sometimes a person responsible for completing a cleanup is not able to locate and properly abandon a groundwater monitoring well, usually because the top has been broken off. The open pipe provides an easy route for pollutants at the surface to reach the groundwater. In addition to any other continuing obligations in the state’s closure letter, these property owners must properly abandon the monitoring well in accordance with Chapter NR 141.25, Wis. Admin. Code [exit DNR], as soon as the well can be located.

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Locating Continuing Obligations on the Internet

DNR’s GIS Registry is Wisconsin’s map-based system to find properties with continuing obligations due to residual contamination. This information may be helpful to property owners, purchasers, lenders, local government officials and others.

The GIS Registry includes copies of maps, data tables and the state’s closure letter (in PDF format), as well as links to more information in DNR’s on-line databases. A good source of information is the state’s closure letter. This letter states that no additional environmental cleanup is needed in the specified area, closes the state’s active file and includes specific information about the continuing obligations and how to manage the area of residual contamination.

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For more information about this page, contact:

Mark Gordon
608.266.7278

Last Revised: Thursday July 02 2009