The development of chemical-specific cleanup standards for use under the Massachusetts Contingency Plan (MCP) represents an important piece of the effort to streamline the site assessment and remediation program. The MCP Numerical Standards provide a simple means to determine whether remediation is necessary at a site and when no further remedial response action is necessary.
While the MCP retains site-specific risk assessment as an optional means (Method 3) to establish the need for remediation and to determine cleanup goals, the time and cost of preparing such assessments may not be warranted at many of the M.G.L. c.21E sites. Promulgated standards (Method 1) provide an option that is simple to use and results in predictable outcomes. The Department also offers a hybrid methodology (Method 2) that allows limited modification of the Method 1 Standards based upon site-specific information. All three Methods address the potential risk of harm to health, public welfare and the environment. Risk to safety is considered separately.
In addition to the promulgated Method 1 cleanup standards, the MCP contains other lists of numerical values. Upper Concentration Limits (UCLs) are used under Risk Characterization Methods 2 and 3. Reportable Quantities (RQs) and Reportable Concentrations (RCs) are used to determine notification requirements.
Method 1 Standards
The MCP Method 1 Standards represent levels of oil or hazardous materials at which no further remedial response actions would be required based upon the risk of harm posed by these chemicals. The standards are protective of public health, public welfare, and the environment (i.e., represent a condition of "no significant risk"), given the exposures assumed, and are measurable.
Method 1 standards are, by nature, generic, and are derived in a manner to be protective at a wide range of disposal sites across the state. The use of such generic standards is one risk characterization option in the Massachusetts Contingency Plan. It is important to remember that the flexibility exists under the MCP to use more site-specific risk characterization approaches under Methods 2 and 3.
Categories of Standards
The criteria that determine the applicability of the groundwater standards are described in regulation at 310 CMR 40.0932. Click on the link below for more information on the specific groundwater standards, including the methodology to derive the standards.
Category GW-1 : Concentrations based on the use of groundwater as drinking water, either currently or in the foreseeable future.
Category GW-2 : Concentrations based on the potential for volatile material to migrate into indoor air.
Category GW-3 : Concentrations based on the potential environmental effects resulting from contaminated groundwater discharging to surface water.
The criteria that determine the applicability of the soil standards are described in regulation at 310 CMR 40.0932. Click on the link below for more information on the specific soil standards, including the methodology to derive the standards.
Category S-1 : Concentrations based on sensitive uses of the property and accessible soil, either currently or in the foreseeable future. Additional criteria are established for the protection of groundwater, based on the leaching potential of the contaminated soil.
Category S-2 : Concentrations based on property uses associated with moderate exposure and accessible soil, either currently or in the foreseeable future. Additional criteria are established for the protection of groundwater, based on the leaching potential of the contaminated soil.
Category S-3 : Concentrations based on restricted access and property with limited potential for exposure, either currently or in the foreseeable future. Additional criteria are established for the protection of groundwater, based on the leaching potential of the contaminated soil.
Method 2 Standards
Under the MCP's Method 2 Risk Characterization approach, Method 1 Standards may be supplemented or modified with site- and chemical-specific information. The term "MCP Method 2 Standards" refers both to soil and groundwater standards developed de novo under Method 2 and Method 1 Standards that have been modified under Method 2 to account for site-specific fate-and-transport considerations.
In addition, the MCP provides (310 CMR 40.0982(7)) that the Department may publish optional sets of chemical-specific standards that may be used under Method 2.
More detail is available on options available under Method 2, including links to published standards.
Upper Concentration Limits (UCLs)
"Upper Concentration Limits" in groundwater and soil are promulgated to minimize potential risks associated with uncontrolled environmental contamination, and the costs associated with cumulative anthropogenic contributions to "background".
More detail is available on the derivation of the UCLs and their application under both Method 2 and Method 3.
Reportable Quantities and Concentrations
Reportable Quantities ("RQs") define notification requirements for sudden releases (or spills) of oil or hazardous materials to the environment.
Reportable Concentrations ("RCs") define notification requirements for contamination discovered in soil and groundwater.
See the online Oil and Hazardous Materials List for RQ and RC values.