MGL c. 21E, s 3A(g) requires that, to be cleaned up permanently, 21E sites need to attain a condition that poses no significant risk to health, safety, the environment, and public welfare. Decisions about risks from a site must consider both current and future uses of the property and affected groundwater. The Massachusetts Contingency Plan ("MCP" 310 CMR 40.0000, the regulations implementing MGL c. 21E) establishes rules for ensuring that groundwater cleanups meet this standard. One of the MCP criteria for groundwater cleanup is directed at protecting groundwater quality in high and medium yield aquifers that are reasonably foreseeable sources of public drinking water, so-called Potentially Productive Aquifers (PPAs; see 310 CMR 40.0006). In PPAs, cleanups must restore groundwater to drinking water quality to be considered permanent solutions.

The current definition of PPA exempts groundwater beneath municipalities with a population density of 4,400 people/square mile (that lie over PPAs) from having to meet MA Drinking Water Standards. Due to dense development patterns in these municipalities, the siting of new groundwater sources of drinking water is unlikely. This exemption is problematic because: some of the 27 communities that met the 4,400 people/square mile census want to protect the groundwater for a future water supply and require that cleanups make the water safe to drink; other communities, that do not meet the exemption criterion, have densely settled areas and/or industrial/commercial areas in which it is unlikely that a new public well will be sited, but cleanups in these areas are still required to meet MA Drinking Water Standards. Where other groundwater cleanup standards apply, they generally allow less stringent cleanup and therefore have substantially lower costs associated with compliance.

On September 9, 1996, revised regulations governing cleanup requirements within Potentially Productive Aquifers or "PPAs" (as defined in the MCP) took effect.

The definition of PPA has been improved to more clearly identify areas that are foreseeable groundwater sources of drinking water. These areas, where cleanups will be required to meet MA Drinking Water Standards, will be called Potential Drinking Water Source Areas. The areas that are unlikely future drinking water sources due to heavy urbanization will be called Non-Potential Drinking Water Source Areas (where meeting drinking water standards will not be required, often allowing for less costly cleanups). Cleanups in Current Drinking Water Source Areas will continue to be required to meet MA Drinking Water Standards.

SUMMARY OF REGULATIONS (effective 9/9/96):

  • The new approach will replace the MCP's current town-wide population density criterion (4400 people/square mile) by criteria in the MCP based on specific existing "heavily urbanized" land uses and more finely focused population density census information to define "Non-Potential Drinking Water Source Areas" (NPDWSAs). These areas must be at a minimum of 100ac.
  • DEP in conjunction with MassGIS has produced a mapping overlay which illustrates the NPDWSAs. These maps are based on USGS hydrologic data, the most recent land use information available to MassGIS (based on McConnell maps), and US Census information. These maps are available for purchase (as of 9/9/96) and are provided as guidance.
  • "Non-Potential Drinking Water Source Areas" may also include additional areas within PPA's that are identified in a new case-specific petition process asserting that:
    • an aquifer is contaminated and cannot be cleaned up feasibly, but land uses/population density do not meet the criteria for a "Non-Potential Drinking Water Source Area", and
    • the municipality(ies) overlying the affected groundwater concurs with the petition (if it is submitted by a private party), stating in effect that it will not look to this aquifer for a future water supply.
    • Petitions for these individual designations of "Non-Potential Drinking Water Source Areas" may be submitted to the Department of Environmental Protection by either a private party or a municipality after public notice and an opportunity for public comment. The DEP Commissioner will act on these petitions, based on findings from a review by the Department and the Massachusetts Water Resources Commission.
  • Areas that a municipality has identified and taken legal steps to protect as a potential source of drinking water will be included in "Potential Drinking Water Source Areas". These include areas designated by zoning or other local ordinance, by an inter-municipal contract, or by a location-specific contract with a water supplier (e.g., the MWRA or a local water district). Groundwater cleanups in these areas must meet drinking water standards to achieve a permanent solution under the MCP (even though all or part may be "heavily urbanized"). This requirement will apply to all aquifers (i.e., it is not be limited to high and medium yield aquifers). "Potential Drinking Water Source Areas" will include municipal ordinances that are adopted after the PPA regulations take effect (from the date on which they are adopted in the future) as well as ordinances, contracts, etc. that are already adopted.