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.
