310 CMR, § 40.0942 - Selection of Method to Characterize the Risk of Harm to Health, Public Welfare and the Environment

The three Methods for Risk Characterization described in 310 CMR 40.0941(3) have been developed to provide a range of approaches which vary in detail and circumstances of use, each of which provides equivalent levels of protection to health, public welfare and the environment. Any of the three Risk Characterization Methods may be employed at a disposal site, subject only to the following limitations:

(1) Method 1 relies upon the use of numerical standards for chemicals in groundwater and soil to characterize risk of harm to health, public welfare and the environment. These standards are referred to as "MCP Method 1 Standards", and are listed in 310 CMR 40.0970 through 310 CMR 40.0979. Method 1 shall only be used to characterize risk at a disposal site if there is a promulgated MCP Method 1 Standard for each oil and hazardous material of concern at the disposal site.

(a) If no MCP Method 1 Standard has been promulgated for one or more oil or hazardous material in soil or groundwater at the disposal site, then the following options are available:

1. The RP, PRP or Other Person may develop such standards under Method 2. Such standards may be used alone or in combination with other MCP Method 1 Standards to characterize risk at the disposal site. A combined Method 1 and Method 2 approach shall be considered a Method 2 Risk Characterization; or

2. Method 3 alone may be used to characterize risk at the disposal site.

(b) If oil or hazardous material at the disposal site is present in, or is likely to migrate at potentially significant concentrations to an environmental medium in addition to groundwater and soil (such as in sediments, within surface water, or within ambient or indoor air), then Method 1 alone shall not be used to characterize the risk at the disposal site, and the following options are available:

1. If it is demonstrated that the current or foreseeable future human exposure to the oil and/or hazardous material would occur predominantly through contact with the groundwater or soil, then the MCP Method 1 Standards may be used to characterize the risk of harm to human health posed by the disposal site. Method 3 then would be used to characterize the risk of harm to public welfare and the environment posed by the contamination in all other affected media. Such an approach shall be considered to be a combined Method 1 and Method 3 Risk Characterization; or

2. Method 3 alone may be used to characterize risk at the disposal site.

(c) If Environmental Receptors have been identified for the disposal site as described in 310 CMR 40.0922, and if oil and/or hazardous material known to bioaccumulate are present within two feet of the ground surface, then Method 1 alone shall not be used to characterize the risk at the disposal site, and the following options are available:

1. The MCP Method 1 Standards may be used in combination with a Method 3 Stage I Environmental Screening to characterize the risk of harm to health, public welfare and the environment. Such an approach shall be considered to be a combined Method 1 and Method 3 Risk Characterization; or

2. Method 3 alone may be used to characterize risk at the disposal site.

(d) If one or more Volatile Organic Compounds is present in vadose zone soil adjacent to an occupied structure (within six feet, measured horizontally from the wall of the structure, and within ten feet, measured vertically from the basement floor or foundation slab) then the soil has the potential to result in significant indoor air concentrations of OHM and Method 1 alone cannot be used to characterize the risk at the disposal site. The following options are available:

1. The MCP Method 1 Standards may be used in combination with a demonstration that the soil concentrations of Oil and Hazardous Material are not likely to be a significant contributor to the Cumulative Receptor Risk at the site by the indoor air exposure pathway.

2. MCP Method 3 alone may be used to characterize risk at the disposal site.

(e) If the current and/or reasonably foreseeable future use of the site includes non-commercial gardening of edible produce pursuant to 310 CMR 40.0923, then the following options are available:

1. A Method 1 Risk Characterization alone may be used to characterize risk at a site, if otherwise applicable; or

2. A Method 3 Risk Characterization may be used to characterize risk at the site. The risk associated with the ingestion of produce from non-commercial gardening must be quantitatively evaluated in the Method 3 Risk Characterization unless the Exposure Pathway associated with such ingestion has been addressed through the implementation (for current use) and/or recommendation (for reasonably foreseeable future use) of Best Management Practices for Non-commercial Gardening. The Risk Characterization and Permanent Solution with Conditions must include documentation and discussion of the concentrations of contaminants in the soil, acknowledgement of the potential for uptake into the edible portions of the plant and the potential for exposure that may result from harvesting and consuming the produce, and description of the Best Management Practices for Non-commercial Gardening that minimize or eliminate such exposure.

(2) Method 2 allows the consideration of limited site-specific information to supplement the use of MCP Method 1 Standards for groundwater and soil. As a result, the limitations and options described for the use of Method 1 in 310 CMR 40.0942(1) are also applicable to the use of Method 2.

(3) Method 3 may be used at any disposal site to characterize the risk of harm to health, public welfare and the environment.

Notes

310 CMR, § 40.0942

Amended by Mass Register Issue 1503, eff. 3/1/2024. Amended by Mass Register Issue S1516, eff. 3/1/2024.