The Massachusetts Department of Environmental Protection (DEP) has made significant changes to the regulations governing the cleanup of contaminated sites in the Commonwealth (310 C.M.R. §§40.0000, et seq., known as the Massachusetts Contingency Plan, or the MCP). The majority of the changes became effective on June 20, 2014. These changes will have implications on sites currently in the MCP system and on those currently being assessed. Highlights of the amendments include:   

  • New Terminology for End Points. In order to provide more transparency, the term “Response Action Outcome” (RAO) (formerly used to describe the completion of remediation) is being retired. The amendments introduce new terms – “Permanent Solution” and “Temporary Solution” -- to indicate that remediation has been completed at a site. There will no longer be various classes of RAOs to indicate closure but rather Permanent Solution, Permanent Solution with Conditions (including Activity and Use Limitations [AULs], among others) and Temporary Solution.  The concept of Permanent Solution with Conditions introduces additional important changes. As would be expected, one Permanent Solution with Conditions includes scenarios where an AUL is required to confirm that no significant risk is posed by contaminants that may remain in the environment. Now, a Permanent Solution can also be achieved where conditions are imposed but no AUL is required. DEP includes several scenarios as candidates for these types of closure: (1) where Historic Fill remains in place (discussed below), (2) where contaminants remain under roadways/railroad rights-of-way, (3) where contaminants remaining would pose a risk to residential use only if residential gardening were undertaken without the imposition of certain best management practices and (4) where there exists the potential for the construction of future buildings at sites for which data suggest indoor air concerns could exist.   
  • Expansion of Time and Tiering of Sites. The amendments generally provide additional time (one to two years) to move through phases of the MCP cleanup process, although closure/completion is still sought within five years.

The amendments eliminate the cumbersome and costly numerical ranking system tier classification process, instead providing clear criteria to determine when a site should be classified as Tier I. In addition, Tier I sites will no longer require permits. The new Tier I criteria are (1) issues in Current Drinking Water Source Areas, (2) the presence of an Imminent Hazard, (3) where Immediate Response Actions (IRAs) are ongoing to address a Critical Exposure Pathway (CEP) and (4) where IRAs and remedial actions are ongoing. When criteria warranting the Tier I classification are addressed, reclassification can occur.   

  • AUL Streamlining. DEP has changed AUL documentation requirements to eliminate the AUL Opinion. There is a new requirement mandating that copies of deeds of properties subject to an AUL be submitted to the DEP within 30 days of recording/registering (this requirement falls on both the Grantor and the Grantee but is fulfilled by submittal by either). The AUL form has been amended to highlight this requirement.  
  • Modifications Related to Vapor Intrusion. Vapor intrusion is an important factor in the regulatory changes. One important change will enable closure at sites with active sub-slab depressurization systems. Until now, such sites could not be permanently closed. The amendments provide that such sites may now be closed using Permanent Solution with Conditions -- introducing a new acronym for Active Exposure Pathway Mitigation Measures (AEPMMs). Closure would be implemented with an AUL incorporating certain standardized conditions, including the use of remote telemetry to ensure system operation, a requirement that DEP and affected parties in the impacted building be notified of any system shutdown lasting for 30 consecutive days, financial certification of availability of funds in the event of necessary repairs, and an annual certification that the system is operating and that the owner is aware of the requirement to maintain the system.   
  • Changes Impacting Sites Involving Non-Aqueous Phase Liquids (NAPLs). Prior to the MCP amendments, sites where there was 1/2 inch or more of NAPLs in groundwater could not be permanently closed (NAPLs at that measurement were characterized as the exceedance of Upper Concentration Limits/UCLs). The changes replace the 1/2-inch NAPL UCL to enable a Permanent Solution when (1) “Non-Stable NAPL” is absent, (2) NAPL has been removed to the extent feasible and (3) an AUL is imposed where there is “Microscale Mobility.”   
  • MCP Standards for Contaminants Have Been Updated. Of 1,928 MCP Numerical Standards for contaminants, 408 values have gone up (now less stringent), 192 values have gone down (now more stringent) and 1,328 values have not changed. Notable changes in values becoming more stringent include standards for lead, PCBs and TCE.   
  • Historic Fill. The amendments make important changes to sites impacted by Historic Fill. As noted above, the new closure category of Permanent Solution with Conditions (and no AULs) expressly includes a provision relating to Historic Fill -- sites may now be closed when the remaining elevated contaminants resulted from Historic Fill and other general human activities. Background now expressly includes Natural Background and Anthropogenic Background, which include Historic Fill. For Natural Background, sites can typically be closed without conditions. Where oil/hazardous material is attributable to Historic Fill, it should be analyzed under the new Anthropogenic Background provisions. Historic Fill (1) includes materials placed prior to January 1, 1983; (2) may contain metals, petroleum, PAHs, construction and demolition debris, and wood/coal ash; and (3) may not contain oil/hazardous materials originating from any operations or any generated hazardous waste. Again, sites containing materials meeting the definition of “Historic Fill” can be closed with a Permanent Solution with Conditions.


This is intended to provide a broad overview of some of the important changes to the MCP. Parties should consider potential implications to specific sites and facts carefully.