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40.0900: Procedures and Standards for the Characterization of the Risk of Harm to Health, Safety, Public Welfare and the Environment

310 CMR 40.0901 through 40.0999, cited collectively as 310 CMR 40.0900, describes the procedures for evaluating the risks posed by oil and/or hazardous material at disposal sites.

40.0901: Applicability and General Requirements

(1) The procedures, criteria and standards of 310 CMR 40.0900 are applicable to all disposal sites for which response actions are required by M.G.L. c. 21E and/or 310 CMR 40.0000.

(2) The general procedures and standards which apply to all Risk Characterizations are described in 310 CMR 40.0901 through 40.0939. Requirements which are specific to the type and method of Risk Characterization being performed are described in 310 CMR 40.0940 through 310 CMR 40.0999.

(3) The characterization of risk of harm to health, safety, public welfare, and the environment is not required for a disposal site, environmental medium, or chemical for which response actions have successfully reduced concentrations to background levels, as described in 310 CMR 40.1020.

(4) The characterization of the risk of harm to health, safety, public welfare and the environment shall be performed in a manner consistent with scientifically acceptable risk assessment practices, and shall take into consideration guidance published by the Department.

40.0902: Purpose of the Risk Characterization

A characterization of the risk of harm to health, safety, public welfare and the environment is performed at disposal sites to provide the quantitative and qualitative information used to evaluate the need for remedial actions:

(1) Risk Characterization is used to identify and evaluate site conditions which may pose an Imminent Hazard. The methodology used in this evaluation is described in 310 CMR 40.0950.

(2) Risk Characterization is used to establish whether a level of No Significant Risk exists or has been achieved at a disposal site. The criteria used in this determination are described in 310 CMR 40.0900, and two basic approaches to Risk Characterization are utilized:

(a) A chemical-specific approach, which compares site concentrations to standards in soil and ground water, as described in 310 CMR 40.0970 through 40.0989. For the disposal sites to which they are applicable, these standards have been developed to meet the same objectives of the cumulative risk approach described in 310 CMR 40.0902(2)(b).

(b) A cumulative risk approach which compares site-specific information to a Cumulative Cancer Risk Limit of an Excess Lifetime Cancer Risk of one-in-one hundred thousand, a Cumulative Noncancer Risk Limit which is a Hazard Index equal to one, promulgated health, safety, public welfare and environmental standards, and site-specific conditions, as described in 310 CMR 40.0990 through 310 CMR 40.0999.

(3) Notwithstanding the criteria described in 310 CMR 40.0902(2), if the concentration of an oil and/or hazardous material at the disposal site is at or below background levels, then that oil and/or hazardous material shall be considered to pose No Significant Risk. Disposal sites at which all oil and hazardous material have been reduced to background levels are eligible for a Class A-1 Response Action Outcome, as described in 310 CMR 40.1036(1), even if such background levels exceed one or more of the numerical standards or risk criteria published in 310 CMR 40.0900.

(4) The results of the Risk Characterization shall be the basis for a decision whether a remedial action is necessary and to select the appropriate Response Action Outcome for the disposal site pursuant to 310 CMR 40.1000.

(5) "Screening" Risk Characterizations may be performed using worst-case exposure assumptions to quickly demonstrate that a condition of No Significant Risk exists or has been achieved at a disposal site. If such a conclusion cannot be reached following a screening Risk Characterization, a more detailed assessment is appropriate.

40.0903 Scope of the Risk Characterization and Supporting Documentation

(1) The scope and level of effort of the Risk Characterization shall depend on the complexity of the disposal site and the response action being performed. The Risk Characterization shall be of sufficient scope and adequately documented to demonstrate that the Response Action Performance Standard (RAPS) has been met in accordance with 310 CMR 40.0191.

(2) The length and complexity of the documentation of the Risk Characterization shall depend upon the nature of the site and the response action being performed, as well as the method of Risk Characterization being performed. The documentation may be written as a separate report or as one or more components of another submittal required pursuant to 310 CMR 40.0000.

40.0904: Site Information Required for Risk Characterization

An adequate characterization of the disposal site is a prerequisite to the characterization of risk of harm to health, safety, public welfare and the environment, although the appropriate type and amount of information required to complete a Risk Characterization will depend on the unique characteristics of a release and/or disposal site. Particular attention shall be paid to the following site assessment parameters:

(1) Physical Characteristics. The physical characteristics of the disposal site, including, but not limited to, the topography, geology, hydrogeology, and surface characteristics shall be evaluated as warranted by release and site conditions and described in sufficient detail to support the Risk Characterization.

(2) Extent of Release. The documentation of the Risk Characterization shall contain a description of the source and extent of the release of the oil and/or hazardous material, including, where appropriate:

(a) the horizontal and vertical extent and concentrations of oil and/or hazardous material in all evaluated media;

(b) background concentrations of oil and/or hazardous material in all evaluated media; and

(c) all existing or potential Migration Pathways, including, but not limited to: soil, ground water, surface water, air, sediment and the food web. Concentrations of oil and hazardous material in the sediment and/or surface water must be measured in any of the following circumstances to determine whether such material at or from the site has been or is being transported in a manner that would result in surface water or sediment concentrations of potential ecological significance, unless the need for such measurements is obviated by a technical justification consistent with 310 CMR 40.0193:

1. Hazardous materials at or from the site, excluding VOCs, are present in ground water within 200 feet of a surface water body;

2. Hazardous materials at or from the site, excluding VOCs, are present in the ground water at concentrations higher than the GW-3 standard(s) within 500 feet of a surface water body;

3. Nonaqueous phase liquid (NAPL) at or from the site is present within 200 feet of a surface water body;

4. Historical evidence indicates past discharge or dumping of oil or hazardous material from the site to the surface water body, unless such discharges were permitted;

5. Evidence indicates current or past runoff of oil or hazardous material from or with site soil into the surface water body; and

6. Site-specific conditions indicate that oil or hazardous material from the site may reasonably be expected to be present in the sediment or surface water at concentrations of potential ecological significance.

(3) Characterization of the Oil and/or hazardous Material. The documentation of the Risk Characterization shall describe the oil and/or hazardous material at the disposal site, including, without limitation and where appropriate:

(a) type, volume, composition, nature, physical, chemical and toxicological characteristics; and

(b) environmental fate and transport characteristics, including mobility, stability, volatility, ability and opportunity for bioaccumulation, and persistence in the environment.

40.0920: Receptor Information Required For Risk Characterization

The identification of receptors, Site Activities and Uses, Exposure Points and Exposure Point Concentrations shall be conducted in a manner which provides a conservative estimate of the exposure to oil and/or hazardous material which a receptor may receive within the contaminated area over a period of time.

40.0921: Identification of Human Receptors

The documentation of the Risk Characterization shall identify and describe the Human Receptors who are likely to be present at the disposal site or in the surrounding environment, and who, as a result, would likely be exposed to oil and/or hazardous material.

(1) The identification of the Human Receptors shall consider the current and reasonably foreseeable uses of the disposal site and the surrounding environment.

(2) The Human Receptors identified shall not be specific individuals, but shall be described as groups of individuals.

(3) Subpopulations which may be at increased risk due to increased sensitivity, particular behavior patterns or current or past exposures to chemicals in the environment shall be identified as distinct receptors.

(4) The Human Receptors shall be described in terms such as age group, occupation or other characteristics which will distinguish them from the general population. Examples of such descriptions include, without limitation:

(a) lifelong residents at the disposal site;

(b) trespassers;

(c) women of childbearing age;

(d) construction workers; and

(e) children, ages one to eight years.

40.0922: Identification of Environmental Receptors

The documentation of the Risk Characterization shall identify and describe the Environmental Receptors which are likely to be present at the disposal site or in the surrounding environment and which, as a result, would likely be exposed to oil and/or hazardous material.

(1) Examples of such biota may include, but are not limited to:

(a) wildlife, such as deer, squirrel and fox;

(b) fish and shellfish; and

(c) plants, such as grasses and trees.

(2) Examples of such habitats may include, but are not limited to:

(a) Areas of Critical Environmental Concern;

(b) surface water;

(c) fresh and saltwater fisheries and fish habitat, including, but not limited to, shellfish areas; and

(d) wetlands.

(3) Any Species of Concern, Threatened Species, or Endangered Species which is known or likely to be located at the disposal site or in the surrounding area shall be specifically identified as an Environmental Receptor.

40.0923: Identification of Site Activities and Uses

The documentation of the Risk Characterization shall identify and describe the Site Activities and Uses associated with the disposal site and the surrounding environment. These activities shall be used in combination with the criteria described in 310 CMR 40.0930 through 40.0939 to identify applicable ground water and soil categories and to estimate the nature and magnitude of exposure pursuant to 310 CMR 40.0990.

(1) The Site Activities and Uses shall include all current and reasonably foreseeable uses and activities occurring at the disposal site or in the surrounding environment which could result in exposure to oil and/or hazardous material by Human or Environmental Receptors.

(a) The identification of Site Activities and Uses of the ground water shall be determined independent of the activities and uses of the land itself.

(b) The Site Activities and Uses of the land shall be identified without regard to whether the land is currently developed or undeveloped.

(c) The selection of site-specific exposure frequency and exposure duration should be representative of the full extent of site activities consistent with the identified Site Use.

(2) The current Site Activities and Uses associated with the land itself, with structures in and on the land, and with the ground water, surface water, soil, sediment or other medium which could result in exposure of Human or Environmental Receptors to oil and/or hazardous material shall be identified and described. This evaluation shall include consideration of activities which actually may not be occurring at the time of the evaluation, but which are consistent with the current use of the disposal site and surrounding environment and may reasonably be expected to occur.

(3) The reasonably foreseeable Site Activities and Uses shall include any possible activity or use that could occur in the future to the extent that such activity or use could result in exposures to Human or Environmental Receptors that are greater than the exposures associated with current Site Activities and Uses, except that:

(a) the ground water shall not be considered a reasonably foreseeable source of drinking water unless it is considered to be in category GW-1 pursuant to the criteria listed in 310 CMR 40.0932(4); and

(b) specific Site Activities and Uses which would be reasonably foreseeable pursuant to 310 CMR 40.0923(3) may be eliminated from further consideration through the use of Activity and Use Limitations in accordance with 310 CMR 40.1012 and 310 CMR 40.1070 through 40.1089.

(4) If the Site Activities and Uses considered in the Risk Characterization will be limited in any way through Activity and Use Limitations, as described in 310 CMR 40.1012, or by a restriction imposed by a government agency which is or will be in place, then the documentation of the Risk Characterization must clearly and concisely state the nature of the limitations and describe the Site Activities and Uses which must be prohibited by such Activity and Use Limitations or government restrictions.

(a) The assessment of current Site Activities and Uses shall not be limited by Activity and Use Limitations and/or government restrictions that are not in place or not effective.

(b) The results of the Risk Characterization shall not be considered valid unless and until all necessary government restrictions are in place and/or all Activity and Use Limitations have been recorded, registered or filed in accordance with 310 CMR 40.1070 through 40.1089.

(5) If the Site Activities and Uses considered in the Risk Characterization have been limited in any way by temporary risk reduction measures (e.g., fences which restrict access) employed at the disposal site, or by presumed future response actions, the documentation of the Risk Characterization shall describe clearly and concisely the nature of all such limitations. The documentation of the Risk Characterization shall clearly and concisely state that:

(a) the conclusions presented are based upon the described temporary measures and/or the implementation of described future response actions; and

(b) the conclusions are valid only if, and as long as, the site conditions or the temporary measures are maintained and/or the presumed response actions have been implemented as described.

(6) Examples of Site Activities and Uses associated with Human Receptors include, without limitation:

(a) the use of a building as an office, store or residence;

(b) the use of water as drinking water, for washing floors or watering lawns;

(c) the cultivation of fruits and vegetables destined for human consumption (e.g., gardening or farming) and the cultivation of ornamental plants;

(d) the excavation of soil;

(e) recreational activities, such as playing baseball, swimming, fishing and hiking;

(f) leisure activities, such as picnicking, sunbathing and entertaining;

(7) Examples of Site Activities and Uses associated with Environmental Receptors include, without limitation:

(a) foraging by wildlife;

(b) the support of plant or wildlife populations; and

(c) the seasonal use of a location for nesting or mating.

40.0924: Identification of Exposure Points

(1) All potential Exposure Points shall be identified and described in the documentation of the Risk Characterization after considering the site and receptor information described in 310 CMR 40.0904 through 40.0923.

(2) The identification of an Exposure Point shall be consistent with the type and method of Risk Characterization which is being performed.

(a) Methods 1 and 2 Risk Characterizations - The Exposure Point(s) in groundwater and soil shall be identified and documented for all current and reasonably foreseeable Site Activities and Uses.

1. For groundwater, the Exposure Point(s) shall be the groundwater resource itself, as measured at each wellhead and/or nearest tap of a well screened within the horizontal and vertical distribution of the oil and/or hazardous material in the groundwater. Existing water supply wells and monitoring wells shall be used to represent current or potential groundwater Exposure Points.

2. For soil, the Exposure Point(s) shall be defined by the horizontal and vertical distribution of the contaminated soil in combination with the soil category(ies) determined to be applicable. For a contiguous volume of contaminated soil comprised of one or more soil categories as defined in 310 CMR 40.0933, a separate and distinct Exposure Point shall be represented by the soil in each category.

(b) Method 3 Risk Characterization B The Exposure Point(s) in all environmental media shall be identified for all current and reasonably foreseeable Site Activities and Uses.

1. For comparisons to Applicable or Suitably Analogous Standards, the Exposure Point shall be identified in a manner consistent with the applicable regulations.

2. Except as provided in 310 CMR 40.0924(2)(b)3., in GW-1 groundwater areas, for the comparison to drinking water standards listed in 310 CMR 22.00 and for the calculation of current and/or potential exposure to the groundwater, the Exposure Point(s) shall be the groundwater resource itself, as measured at each wellhead and/or nearest tap of a well screened within the horizontal and vertical distribution of the oil and/or hazardous material in the groundwater. Existing water supply wells and monitoring wells shall be used to represent current or potential groundwater Exposure Points.

3. In GW-1 areas that are designated GW-1 solely on the basis of being located within a Zone II or an Aquifer Protection District that overlays or is contiguous with a Zone II and where sites meet the following criteria, the Exposure Point shall be the existing Public Water Supply well(s) for the evaluation of current and future drinking water exposures and the Exposure Point Concentration shall be identified pursuant to 310 CMR 40.0926(8)

a. Contamination is limited to Oil;

b. A Phase II Report for the disposal site pursuant to 310 CMR 40.0830 has been submitted;

c. The disposal site is located at a distance greater than 1,000 feet from a Public Water Supply well;

d. It has been demonstrated that NAPL is not present at a thickness equal to or greater than 1/2 inch in any environmental medium;

e. It has been demonstrated through adequate characterization of horizontal migration that groundwater contaminant concentrations are

i. not detected at or above analytical limits appropriate for a GW-1 area at the downgradient edge of the plume, at least 1,000 feet from the Public Water Supply well(s), and

ii. decreasing within the boundaries of the plume. Demonstration of diminishing contaminant concentrations within the plume shall consider both the spatial and temporal distribution of the contamination and other measures indicative of biodegradation of the contaminants;

f. It has been demonstrated through adequate characterization of vertical migration that contamination has not entered bedrock including the submittal of a profile sectional map showing the following information:

i. known or inferred depth to bedrock;

ii. depths to the top and bottom of the plume throughout the length of the plume; and

iii. existing well screen depths in comparison to the plume; and

g. It has been demonstrated that there is no potential Exposure Point Concentration in accordance with the criteria specified at 310 CMR 40.0926(8).

4. For current or potential soil exposures, the following depths shall be considered with any applicable site-specific information when determining Exposure Points:

a. zero to three feet for exposures associated with surficial activity;

b. zero to six feet for exposures associated with utility installation and repair; and

c. zero to 15 feet for exposures associated with excavation scenarios and building construction.

5. For other exposures, the Exposure Point shall be identified considering the timing of the exposure, the nature of the potential receptors and the likely frequency of exposure.

(3) Consideration shall be given to the identification of Exposure Points which may be located at a distance from the original source of the release, particularly when the migration of oil and/or hazardous material may result in Exposure Points in addition to those identified under current site conditions.

(4) Hot spots shall be considered distinct Exposure Points.

(5) Examples of typical Exposure Points for disposal sites shall include, without limitation:

(a) an existing public or private water supply;

(b) a future drinking water supply;

(c) a hot spot of contamination in a neighborhood playground;

(d) a volume of subsurface soil at a potential construction site;

(e) a distant shellfish bed.

40.0925: Identification of Exposure Pathways

(1) For each identified receptor at each Exposure Point, the documentation of the Risk Characterization shall identify and describe all probable Exposure Pathways, based upon the media contaminated and the Site Activities and Uses.

(2) The Exposure Pathways considered shall be consistent with the type and method of Risk Characterization which is being performed.

(3) Examples of typical Exposure Pathways shall include, without limitation:

(a) ingestion of soil, produce, water, or biota;

(b) inhalation of air or particulate matter; and

(c) dermal absorption from water or soil.

40.0926: Identification of Exposure Point Concentrations and other Data Criteria

(1) For each oil and/or hazardous material in each medium at each Exposure Point, an Exposure Point Concentration shall be identified and documented.

(2) Exposure Point Concentrations shall be determined or estimated in a manner consistent with the type and method of Risk Characterization which is being performed.

(3) In estimating the Exposure Point Concentration, the objective shall be to identify a conservative estimate of the average concentration contacted by a receptor at the Exposure Point over the period of exposure.

(a) Maximum concentrations shall be used to estimate an Exposure Point Concentration under the following conditions:

1. evaluations of acute exposures;

2. screening assessments that evaluate maximum exposure potential to streamline the assessment process; or

3. evaluations of exposures for which the data available to characterize temporal variability or the spatial distribution of site concentration is limited, including when there is insufficient data to adequately characterize the effects of seasonal variation on ground water contaminant concentrations.

(b) For chronic and subchronic exposures (other than for screening evaluations), the arithmetic average of site data is acceptable as an Exposure Point Concentration, provided either of the following criteria are met:

1. for discrete or composite samples, the arithmetic average is less than or equal to the applicable standard or risk-based concentration limit, 75% of the data points used in the averaging procedure are equal to or less than the applicable standard or risk-based concentration limit, and no data point used in the averaging is ten times greater than the applicable standard or risk-based concentration limit; or

2. a valid justification is provided indicating that the sample mean is unlikely to substantially underestimate the true mean of the concentration of oil or hazardous material at the Exposure Point. Such a demonstration should include, but need not be limited to, consideration of the observed distribution of the data, sampling strategy (including frequency, density, and potential biases), graphical representation of analytical results, and/or statistical analyses.

(c) For chronic and subchronic exposures (other than for screening evaluations), the use of maximum concentrations or the 95th percentile upper confidence limit on the mean, whichever is lower, shall be used to estimate an Exposure Point Concentration when the criteria specified in 310 CMR 40.0926(3)(b) are not met. In such cases, the sample size is likely to be insufficient for the simple arithmetic average to estimate the true value with reasonable confidence and there is a considerable probability of substantially underestimating the mean.

(4) In determining the concentrations to compare to Upper Concentration Limits, the objective shall be to provide a conservative estimate of the average concentration within the site, and the average concentration within any Hot Spots within the site. A conservative estimate of the average concentration should be developed in accordance with 310 CMR 40.0926(3).

(5) In determining the concentrations to evaluate Hot Spots, the objective shall be to provide a conservative estimate of the average concentration within the Hot Spot. A conservative estimate of the average concentration should be developed in accordance with 310 CMR 40.0926(3).

(6) Exposure Point Concentrations may be developed using monitoring data gathered during the site investigation or, when appropriate, through the use of fate and transport models generally accepted by the environmental modeling community.

(7) Any mathematical equations or models used to identify Exposure Point Concentrations shall be clearly documented.

(8) No exposure potential exists (the Exposure Point Concentration may be set equal to zero) for those sites described at 310 CMR 40.0924(2)(b)3. if the following conditions are met and documented based on data collected at the disposal site:

(a) Demonstration of source elimination at the disposal site as described in 310 CMR 40.1003(5);

(b) Demonstration of diminishing contaminant concentrations throughout the horizontal and vertical extent of the plume;

(c) Demonstration that contaminant concentrations are not detected at or above analytical limits appropriate for a GW-1 area at the downgradient edge of the plume, at least 1,000 feet from the Public Water Supply well; and

(d) The demonstrations pursuant to 310 CMR 40.0926(8)(b) and (c) are confirmed by a minimum of two years of quarterly groundwater monitoring conducted after the termination of any Active Remedial System and after the achievement of such contaminant concentrations.

40.0930: Identification of Site Ground Water And Soil Categories

40.0931: Purpose

Categories of ground water and soil have been established by the Department for use in the characterization of risk posed by disposal sites. The documentation of a Risk Characterization shall support the categorization of the ground water and soils at the disposal site.

(1) The ground water and soil categories shall be used to determine the applicability of the ground water and soil standards listed in 310 CMR 40.0974(2), 310 CMR 40.0975(6)(a), (b) and (c), and 310 CMR 40.0985(6) when Methods 1 or 2 are used to characterize risk.

(2) The ground water categories shall be used to identify applicable or suitably analogous standards as described in 310 CMR 40.0993(3), when Method 3 is used to characterize risk.

(3) The ground water and soil categories shall be considered in determining the need for Activity and Use Limitations as part of a Response Action Outcome.

40.0932: Identification of Applicable Ground Water Categories

(1) The ground water categories describe the potential for three different types of exposure. More than one category may apply to a single disposal site. In such cases all applicable categories shall be identified.

(2) Ground water at all disposal sites shall be considered a potential source of discharge to surface water and shall be categorized, at a minimum, as category GW-3. The site, receptors, and exposure information identified in 310 CMR 40.0904 through 40.0929 shall be used in conjunction with the criteria listed below to determine if the ground water shall also be categorized as GW-1 and/or GW-2.

(3) The appropriate ground water category shall be identified for both:

(a) ground water currently affected by the release of oil and/or hazardous materials, and

(b) any area to which the ground water affected by the release is expected to migrate.

(4) Ground Water Category GW-1 Except as provided by 310 CMR 40.0932(5), ground water shall be defined as GW-1 if the ground water is located:

(a) within a Current Drinking Water Source Area; or

(b) within a Potential Drinking Water Source Area.

(5) Notwithstanding the provisions of 310 CMR 40.0932(4):

(a) Interim Wellhead Protection Area. Ground water that is categorized as a Current Drinking Water Source Area, solely due to its location within an Interim Wellhead Protection Area, need not be so categorized if it is demonstrated that there is no hydrogeologic connection between the ground water and the public water supply well on the basis of the following:

1. the ground water is hydrogeologically downgradient of the public water supply well based on regional ground water flow and gradient, and beyond the stagnation point. The determination of such a stagnation point shall be based on site-specific parameters and the highest daily approved pumping rate for the public water supply well; or

2. the disposal site is cross-gradient (perpendicular) to regional ground water flow direction and at sufficient distance from the public water supply well such that it is outside of the zone of contribution for the public water supply well. The determination of such a zone of contribution shall be based on site-specific parameters and the highest daily approved pumping rate for the public water supply well; or

3. a hydrogeologic barrier exists between the ground water at the disposal site and the public water supply well.

(b) Potential Drinking Water Source Area. Ground water that is categorized as a Potential Drinking Water Source Area solely due to its location within an area defined as a Potentially Productive Aquifer need not be so categorized if:

1. site-specific information on the types and/or transmissivity of soils shows that the ground water is not located within the true boundary of the medium or high yield aquifer(s) which comprise(s) the Potentially Productive Aquifer; or

2. the ground water within the Potentially Productive Aquifer is naturally brackish, or has naturally high levels of metals, such that the development of the aquifer as a public water supply is currently technologically or economically infeasible.

(c) Case-specific Designation of a Non-potential Drinking Water Source Area.

1. One or more municipalities or private parties may petition the Department to change the categorization of ground water within a Potentially Productive Aquifer from a Potential Drinking Water Source Area to a Non-Potential Drinking Water Source Area because:

a. the ground water is categorized as a Potential Drinking Water Source Area solely due to its location within a Potentially Productive Aquifer, and is not categorized as a Current Drinking Water Source Area;

b. the ground water has been contaminated by one or more releases of oil and/or hazardous materials, and:

1. such releases exceed the reporting thresholds established by 310 CMR 40.0300; and

2. it is not feasible to achieve GW-1 standards for such ground water (pursuant to 310 CMR 40.0860),

c. the land area overlying the ground water does not meet the criteria established in the definition of "Non-potential Drinking Water Source Area" and is at least 100 acres in size; and

d. the municipality(ies) overlying the ground water and any public water systems with existing legal authority to develop new sources of drinking water in the area affected by the petition have sufficient water from other sources to meet their needs for future drinking water supplies, and to fulfill any current contractual obligations for the provision of water to other parties.

2. The petitioner(s) shall provide a reasonable opportunity for public comment on the proposed petition. Such opportunity shall include but not be limited to:

a. establishment of a specific period of time in which written public comment can be submitted to the party preparing the petition. Such comment period shall not be less than 30 calendar days;

b. a public meeting to be held within the public comment period for the purpose of hearing comments on the proposed petition. Such meeting shall be conducted at a time and place convenient to the public;

c. notice of the comment period and meeting shall be provided to:

i. the public using a public notice pursuant to 310 CMR 40.1403(2)(b) in a newspaper of general circulation in the municipalities in the river basin in which the aquifer is located and which are hydrologically connected and downgradient to the area affected by the petition;

ii. the public in the Environmental Monitor;

iii. the public by posting the notice on a publicly accessible location in the municipal office and on any local access cable television station that serves the municipalities described in 310 CMR 40.0932(5)c.1.;

iv. the Chief Municipal Official(s) of (a) the municipality(ies) located within the boundaries of the river basin in which the ground water is located and which are hydrologically connected and downgradient to the area affected by the petition, (b) municipalities abutting the municipality containing the area proposed to be designated as a Non-potential Drinking Water Source Area; and (c) municipalities abutting the abutters;

v. any party with a currently effective contract with the municipality(ies) for sale or purchase of drinking water to or from the aquifer or portion thereof subject to the petition;

vi. any public water system providing water or operating a drinking water well within the municipality(ies) in which the ground water is located and in downgradient municipalities in the subject aquifer; and

vii. any person holding a registration or permit under the Water Management Act (M.G.L. c. 21G) for withdrawal of water from the aquifer or portion thereof subject to the petition.

d. The notice required by 310 CMR 40.0932(5)(c)2.c. shall describe the designation sought, the area to which it would apply, the basis for the petition, how to obtain a copy of the proposed petition, the location and time of the public meeting, and how to submit comments. Such notice shall be provided no later than the first day of the comment period, and not less than 14 calendar days prior to the public meeting;

e. a summary of all comments received shall be prepared after the close of the comment period, noting which comments have been incorporated into the petition and providing an explanation of why others have not. A copy of such summary shall be provided to each person who submitted written comments, and submitted to the Department with the petition.

3. Petitions shall include:

a. a demonstration that the petition meets the criteria for a Case-Specific Designation in 310 CMR 40.0932(5)(c)1.;

b. a water resource budget containing:

1. an inventory of current water supplies and authorized water withdrawal volumes pursuant to MGL c. 21G from the aquifer or portion thereof subject to the petition;

2. forecasts of water demands for the municipality(ies) in which the ground water is located, any municipality in which the ground water plume may be located in the future, and abutting municipalities (such forecasts shall be prepared using the methodology accepted for implementation of 310 CMR 36.00 for forecasting future water needs, using the most current data available);

3. a description of the water resources that will be used to meet the demands identified in 310 CMR 40.0932(5)(c)3.b.2., including the role of the aquifer subject to the petition in meeting such demands, and an analysis of the impact of the development of any future water supply on stream flow, fisheries and wildlife resources, agricultural and other water users;

4. supporting data describing basin hydrology, land uses, existing inter-connections to serve other municipalities, interconnections that have been approved but not yet developed to serve other municipalities, and population trends;

c. documentation of technical and legal actions to protect existing and future drinking water sources;

d. a map of the aquifer showing the area proposed for exclusion from a Potential Drinking Water Source Area;

e. in those cases where the petition addresses a portion of the aquifer, a description of the hydrogeologic relationship between that portion and the larger aquifer (i.e., in terms of ground water flow direction, presence of hydrogeologic barriers);

f. documentation of the public comment period and meeting, and a copy of the summary of comments received required by 310 CMR 40.0932(5)(c)2.e.;

g. one of the following:

i. a certification of concurrence by the Chief Municipal Officer of the municipality(ies) in which the ground water subject to the petition is located and/or any public water systems with existing legal authority to develop new sources of drinking water in the area affected by the petition, stating "The [municipality(ies)] [public water system(s)] [has][have] sufficient water from other sources to meet its [their] need for future drinking water supplies, including the fulfillment of any contractual obligations for the provision of water to other parties". Such certification shall also include a statement that (a) in the event that the ground water will be used in the future as a public drinking water supply, an assessment shall be performed to determine whether additional response actions or wellhead treatment are needed to achieve GW-1 standards and such assessment shall be submitted to the Department with an application for a New Source Approval in accordance with 310 CMR 22.00; and b) that any existing contractual obligations to provide water of potable quality from the ground water subject to the petition to other parties will not be affected by approval of the petition; or

ii. a written statement describing the reasons for not supplying the certification in 310 CMR 40.0932(5)(c)3.g.1. by the municipality(ies) in which the ground water subject to the petition is located or public water systems with existing legal authority to develop new sources of drinking water in the area affected by the petition; or

iii. a copy of a written request for the certification in 310 CMR 40.0932(5)(c)3.g.1.; evidence that such request was received by the appropriate entity(ies); and a certification by the petition sponsor that such certification has not been provided within a period of at least ninety days from the date of the written request.

4. The portions of the petition described in 310 CMR 40.0932(5)(c)3.a. through e. shall be available to the public no later than the date on which the public comment period begins.

5. Petitions shall be submitted to the Department, which shall review the petition and determine whether it is complete. Incomplete petitions will be returned to the applicant with a request for submittal of necessary information within a specified time period. If the requested information is not supplied within the specified time period, the application will be considered to be withdrawn.

6. The Commissioner shall request that the Massachusetts Water Resources Commission review complete applications. Such request shall be made at least 60 days prior to issuing a determination.

7. The Commissioner shall issue a determination not later than 30 days following receipt of a recommendation from the Water Resources Commission as to the disposition of the petition, based on whether the petition meets the criteria established by 310 CMR 40.0932(5)(c)1., as demonstrated by:

a. supporting documentation provided pursuant to 310 CMR 40.0932(5)(c)3.;

b. comments submitted during the public comment period pursuant to 310 CMR 40.0932(5)(c)2. and the petitioner's steps taken to address public concerns; and

c. any other information available to the Department and the Water Resources Commission.

8. The Commissioner may issue a draft determination and request additional public comment and/or review by the Water Resources Commission. Such tentative decision shall establish a timeframe for the additional public comment or Water Resources Commission review, and for issuing a final determination.

(d) Existing Private Wells. Ground water that is categorized as a Current Drinking Water Source Area solely due to its location within 500 feet of a private water supply well need not be categorized as GW-1 if:

1. the private water supply well is removed from service as a source of drinking water and the following conditions are met:

a. written documentation has been submitted to the Department demonstrating that the property(ies) served by the private water supply well has been connected to a public water supply system; and

b. written documentation has been submitted to the Department demonstrating the absence of any unpermitted cross-connection between the private water supply well and public water system or that the private well has been properly abandoned; and

c. where the private well is maintained for uses other than as a private water supply, written documentation has been submitted to the Department in the risk characterization pursuant to 310 CMR 40.0900 demonstrating that such other uses are consistent with a level of No Significant Risk and a Notice of Activity and Use Limitation implemented in accordance with 310 CMR 40.1074 which identifies the use of the private well as a drinking water source as a use which is inconsistent with maintaining a level of No Significant Risk; and

d. copies of the written documentation described in 310 CMR 40.0932(5)(d)1.a. through c. are provided to the local Board of Health; or

2. it is demonstrated that there is no hydrogeologic connection between the ground water and the private water supply well, based on an investigation and evaluation of site-specific conditions, including, but not limited to, as appropriate, the investigation and evaluation of site stratigraphic, potentiometric, and geochemical conditions, and the depth and construction of the private well. The absence of site contaminants in the private well does not, by itself, constitute such a demonstration.

3. the private water supply did not exist at the time of notification pursuant to 310 CMR 40.0300 or was not installed in conformance with applicable laws, by-laws or regulations.

(e) Zone A. Groundwater that is categorized as a Current Drinking Water Source Area solely due to its location within a Zone A need not be categorized as GW-1 if it is demonstrated that there is no hydrogeologic connection between the groundwater and the Class A surface drinking water source, based on an investigation and evaluation of site-specific conditions, including, but not limited to, as appropriate, an investigation and evaluation of site stratigraphic, potentiometric, and geochemical conditions.

(f) The provisions of 310 CMR 40.0932(5)(a) through (d) apply to specific criteria for the inclusion of an area in the GW-1 category. Nothing in 310 CMR 40.0932(5) shall limit the applicability of any other criteria described in 310 CMR 40.0932(4)(a) or (b) to the categorization of groundwater at a disposal site.

(6) Ground Water Category GW-2. Ground water shall be defined to be in category GW-2 if it is located within 30 feet of an existing or planned building or structure that is or will be occupied, and the average annual depth to ground water in that area is 15 feet or less. Category GW-2 ground water is considered to be a potential source of vapors of oil and/or hazardous material to indoor air. Construction of a building in an area in which the average annual depth to ground water is 15 feet or less will change the ground water category at the site to include GW-2; change the activities, uses and/or exposures at the disposal site; and may negate the notification exemption described at 310 CMR 40.0317(17).

40.0933 Identification of Applicable Soil Categories

Soil shall be classified as either category S-1, S-2 or S-3. The site, receptor and exposure information identified in 310 CMR 40.0904 through 40.0929, considering both the current and reasonably foreseeable Site Activities and Uses identified in 310 CMR 40.0923, shall be used in conjunction with the criteria listed below to categorize the soil.

(1) The soil categories shall be applicable to specific volumes of soil which shall be described in written and graphic form in the documentation of the Risk Characterization.

(2) The three soil categories describe a range of the potential for exposure to that soil: Category S-1 soils are associated with the highest potential for exposure, Category S-3 soils have the lowest potential for exposure. While one and only one category is applicable to a specified volume of soil, soils in different areas of a disposal site may be classified in different categories, depending upon their exposure potential.

(3) The Table in 310 CMR 40.0933(9) contains a matrix summarizing the criteria used to categorize soil.

(4) For the purpose of soil categorization, the potential for exposure is described by a qualitative analysis of the accessibility of the soil in combination with the information about the Site Activities and Uses determined pursuant to 310 CMR 40.0923. The following definitions shall be used to describe exposure potential for the purposes of categorizing soil:

(a) Frequency of use shall indicate how often a receptor makes use of, or has access to, the disposal site. Receptor access to and use of the areas around the disposal site are often strong indicators of potential site access and thus should be considered in determining frequency of use for the site under investigation. Frequency of use shall be described as either "High", "Low" or "Not Present", using the following criteria:

1. Children's frequency of use shall be characterized as high if:

a. any children reside, attend school or attend day care at the disposal site; or

b. large numbers of children visit the disposal site, regardless of any one child's frequency of visitation.

2. Adults' frequency of use shall be characterized as high when they reside at the disposal site, or when they work at the disposal site on a continuing basis [i.e., full days or shifts of eight or more hours per day on a continuing basis].

3. Children's or adults' frequency of use shall be characterized as low when they are present at the disposal site, but only as infrequent visitors; or when workers are present at the disposal site for only short periods of time [i.e., less than two hours per day on a continuing basis, or for full days or shifts on a sporadic basis].

4. It shall be presumed that children may be present at the disposal site unless it can be demonstrated that access by children age 15 and younger is specifically restricted or that such children are highly unlikely to be present, in which case children may be considered to be "Not Present". Disposal sites which are residential properties shall presume the presence of children unless there is clear and convincing evidence to the contrary.

5. The frequency of use for activities not described above shall be characterized in the documentation of the Risk Characterization as either high or low.

(b) Intensity of use shall describe the nature of the Site Activities and Uses which could potentially result in exposure to the receptor. Intensity of use shall be described as either "High" or "Low", using the following criteria:

1. Site Activities and Uses which have the potential to disturb soil and thus result in either direct contact with the soil itself or inhalation of soil-derived dust shall be characterized as high intensity use. Examples of such activities include, without limitation, gardening, digging, and recreational sports.

2. Passive activities which do not disturb the soil, such as walking, shopping, and bird watching shall be characterized as low intensity use.

3. The intensity of use for each identified Site Activity and Use shall be characterized in the documentation of the Risk Characterization as either high or low with appropriate justification.

(c) Accessibility of the soil to potential receptors shall be characterized as either "accessible," "potentially accessible," or "isolated" using the following criteria:

1. Soil shall be characterized as "accessible" if it is located less than three feet below the surface, and the surface is not completely covered by pavement. For buildings having earthen floors, the floor shall be considered as the soil surface.

2. Soil shall be characterized as "potentially accessible" if it is located at a depth of three - 15 feet below the surface (with or without pavement), or if the soil is located less than three feet from the surface in an area completely paved.

3. Soil shall be characterized as "isolated" if it is located at a depth greater than 15 feet below the surface, or if the soil is covered completely by a building or other permanent structure which does not have earthen floors, regardless of depth. Soil located at a depth greater than three feet below the earthen floor of a building or other permanent structure shall also be characterized as "isolated."

(5) Category S-1. Soil shall be classified as category S-1 if either:

(a) the soil of concern is accessible, pursuant to 310 CMR 40.0933(4)(c)1., and either:

1. the soil is currently used for growing fruits or vegetables for human consumption, or if it is reasonably foreseeable that the soil may be put to such use; or

2. a child's frequency or intensity of use is considered to be high pursuant to 310 CMR 40.0933(4)(a) and (b); or

3. an adult's frequency and intensity of use are both considered to be high pursuant to 310 CMR 40.0933(4)(a) and (b); or

(b) the soil is potentially accessible, pursuant to 310 CMR 40.0933(4)(c)2., and a child's frequency and intensity of use are both considered to be high pursuant to 310 CMR 40.0933(4)(a) and (b).

(6) Category S-2. Soil shall be classified as category S‑2 if either:

(a) the soil is accessible, pursuant to 310 CMR 40.0933(4)(c)1.; and

1. a child's frequency and intensity of use are both considered to be low pursuant to 310 CMR 40.0933(4)(a) and (b); or

2. children are not present at the disposal site and either (but not both) the adults' frequency or intensity of use is considered to be high, pursuant to 310 CMR 40.0933(4)(a) and (b); or

(b) the soil is potentially accessible, pursuant to 310 CMR 40.0933(4)(c)2.; and

1. either (but not both) a child's frequency or intensity of use is considered to be high pursuant to 310 CMR 40.0933(4)(a) and (b); or

2. children are not present at the disposal site and an adult's frequency and intensity of use are both considered to be high pursuant to 310 CMR 40.0933(4)(a) and (b).

(7) Category S-3. Soil shall be classified as category S-3 if either:

(a) the soil is accessible, pursuant to 310 CMR 40.0933(4)(c)1., and children are not present at the disposal site and an adult's frequency and intensity of use are both considered to be low pursuant to 310 CMR 40.0933(4)(a) and (b); or

(b) the soil is potentially accessible pursuant to 310 CMR 40.0933(4)(c)2.; and

1. a child's frequency and intensity of use are both considered to be low pursuant to 310 CMR 40.0933(4)(a) and (b); or

2. a demonstration has been made that children are not present at the disposal site, and either an adult's frequency or intensity of use is considered to be low pursuant to 310 CMR 40.0933(4)(a) and (b); or

(c) the soil is isolated pursuant to 310 CMR 40.0933(4)(c)3., regardless of any receptor's frequency or intensity of use.

(8) Whenever and wherever reasonable doubts exist over the selection of the appropriate soil category, the soil category associated with the highest exposure potential (among the soil categories being considered) shall be selected.

(9) Table 40.0933(9) contains the Soil Category Selection Matrix.

40.0940: Methods for Characterizing Risk of Harm

40.0941: Approaches to Characterizing Risk of Harm

Several approaches may be employed to characterize the risk of harm to health, safety, public welfare and the environment. The specific Risk Characterization approach used shall depend upon the nature of the risk being assessed, the response action being performed and the nature of the disposal site.

(1) The methodology used to evaluate site conditions which may pose an Imminent Hazard is described in 310 CMR 40.0950 through 40.0959. This methodology shall be used to determine if notification is required pursuant to 310 CMR 40.0321, and if an Immediate Response Action is required by 310 CMR 40.0411 through 40.0429 to abate, prevent, or eliminate an Imminent Hazard.

(2) The methodology used to evaluate the risk of harm to safety shall be as described in 310 CMR 40.0960. A characterization of the risk of harm to safety is required at all disposal sites to determine the need for a response action or to demonstrate that a level of no significant risk of harm to safety exists or has been achieved.

(3) One of the following three options shall be used to determine the need for a remedial action or to demonstrate that a level of no significant risk of harm to health, public welfare and the environment exists or has been achieved:

(a) the characterization of the risk through the use of promulgated standards (hereafter referred to as Method 1), described in 310 CMR 40.0970 through 40.0979; or

(b) the characterizations of risk through the application of promulgated standards supplemented by site-specific information, described in 310 CMR 40.0980 through 40.0989 (hereafter referred to as Method 2); or

(c) the characterizations of risk through the application of site-specific methodologies, described in 310 CMR 40.0990 through 40.0999 (hereafter referred to as Method 3).

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 ground water 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 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 ground water 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 ground water 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 ground water 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 (e.g., 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. Such a demonstration may be based on measured or modeled concentrations in soil gas or indoor air.

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

(2) Method 2 allows the consideration of limited site-specific information to supplement the use of MCP Method 1 Standards for ground water 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.

40.0950: Imminent Hazard Evaluations and Substantial Hazard Evaluations

40.0951: Purpose and Scope of Imminent Hazard Evaluations

(1) The site shall be evaluated to determine if an Imminent Hazard exists in accordance with 310 CMR 40.0000. The decision to conduct a quantitative Imminent Hazard Evaluation shall use the Response Action Performance Standard (RAPS) described in 310 CMR 40.0191, and consider the location and nature of the oil and/or hazardous material, the Human or Environmental Receptors which may be exposed, and appropriate guidance published by the Department.

(2) If the results of this assessment indicate that the conditions at the site pose an Imminent Hazard based upon the criteria described in 310 CMR 40.0955, the Department shall be notified in accordance with 310 CMR 40.0311(7). Subsequent assessments performed as part of an Immediate Response Action shall consider the weight of evidence indicating the potential for an Imminent Hazard when making the evaluations described in 310 CMR 40.0426.

(3) Notwithstanding the provisions of 310 CMR 40.0950 et seq., the concentration of each oil or hazardous material present in a system of water supply used by a public water system, as defined in 310 CMR 22.00, shall not pose an Imminent Hazard or Substantial Hazard for current conditions if the public water system is in compliance with all applicable provisions of 310 CMR 22.00 and any other requirements specified by the Department pursuant to its authority under M.G.L. c.111, s.160 and 310 CMR 22.00.

40.0953: Exposures to be Considered in Imminent Hazard Evaluations

The focus of an Imminent Hazard Evaluation shall be on actual or likely exposures to Human and Environmental Receptors under current site conditions, considering the current use(s) of the disposal site and the surrounding environment, and considering an appropriate short period of time.

(1) The short period of time considered in the evaluation shall be five years unless site circumstances indicate that a shorter time period is appropriate. The specific time period shall be selected in consideration of the nature of the hazard under investigation and the projected time until a Comprehensive Response Action could be completed, in order to determine the need for an Immediate Response Action.

(2) For the evaluation of soil-related exposures, the levels of oil and/or hazardous material at the ground surface or within twelve inches of the ground surface shall be considered in the development of the Exposure Point Concentrations.

(3) For the evaluation of drinking water exposures, the levels of oil and/or hazardous material in the ground water or surface water which serves as the source of the drinking water shall be considered in the development of the Exposure Point Concentrations.

(4) Hot spots shall be the primary, but not exclusive, focus of an Imminent Hazard Evaluation, provided that they are located in areas of actual or likely human exposure under current site conditions.

(5) If a small subset of oil and/or hazardous material are likely to dominate the risk estimates based upon their concentration and toxicity, then the Imminent Hazard Evaluation may be limited to those chemicals.

(6) As indicated by the site conditions, the Imminent Hazard Evaluation shall consider acute, subchronic and/or chronic exposures to the oil and/or hazardous material. The Exposure Point Concentrations shall be developed to reflect the type of exposure being evaluated. The use of upper percentile or maximum concentrations may be appropriate for certain evaluations, and shall be considered as described at 310 CMR 40.0926.

(7) The Imminent Hazard Evaluation shall be conducted in a manner which results in conservative estimates of potential exposures.

(8) The documentation of the Imminent Hazard Evaluation shall clearly identify and explain the basis for exposure parameters chosen for the Risk Characterization.

40.0955: Imminent Hazard Risk Characterization and Outcome

Risk Characterizations for Imminent Hazard Evaluations shall be conducted separately for safety, human health, and the environment, depending on the type of condition that triggered the need for the evaluation, in accordance with the following methods:

(1) The characterization of the risk of harm to safety shall be conducted as described in 310 CMR 40.0960. The conditions at the disposal site pose an Imminent Hazard based on safety concerns if a condition of no significant risk to safety has not been achieved at the disposal site under conditions which actually exist or are about to occur.

(2) The characterization of the risk of harm to human health shall be conducted using Method 3, as described in 310 CMR 40.0993.

(a) The toxicity information used to characterize risk shall be consistent with the type and duration of exposure under evaluation, and shall be clearly identified and documented. Primary consideration shall be given to information developed by the Massachusetts Department of Environmental Protection for the purpose of conducting such risk assessments. Examples of such toxicity information include:

1. Reference Doses and Reference Concentrations; and

2. Carcinogenic Slope Factors and Unit Risk values.

(b) The conditions at the disposal site pose an Imminent Hazard based upon the potential for carcinogenic health effects if, for the oil and/or hazardous material evaluated and for each receptor, the estimated Excess Lifetime Cancer Risk is greater than a cancer risk limit which is an Excess Lifetime Cancer Risk equal to one-in-100,000.

(c) The conditions at the disposal site pose an Imminent Hazard based upon the potential for non-cancer health effects if, for the oil and/or hazardous material evaluated and for each receptor, the non-cancer risk calculated is greater than a non-cancer risk limit of:

1. a Hazard Index (or equivalent ratio of exposure) equal to one for oil or hazardous materials that have the potential to cause serious effects (including but not limited to lethal, developmental, or neurological effects) following short-term exposures, for example lead or cyanide; and

2. a Hazard Index equal to ten for all other oil or hazardous materials.

(d) A release to the environment which produces readily apparent effects to human health poses an Imminent Hazard. A quantitative evaluation of such exposures is not required.

(e) The mathematical equations used to calculate the risk estimates shall be clearly presented and documented.

(3) The risk of harm to the environment shall be characterized based on the data collected pursuant to the response action being performed and the site, receptor, and exposure information identified in 310 CMR 40.0995. The following conditions shall constitute an Imminent Hazard to the environment:

(a) evidence of stressed biota attributable to the release at the disposal site, including, without limitation, fish kills or abiotic conditions; or

(b) a release to the environment of oil or hazardous material which produces immediate or acute adverse impacts to freshwater or saltwater fish populations.

(4) The documentation of the Imminent Hazard Evaluation shall clearly state whether the conditions at the disposal site pose an Imminent Hazard based upon the criteria described in 310 CMR 40.0955(1) through (3).

40.0956: Substantial Hazard Evaluation

(1) The focus of a Substantial Hazard Evaluation shall be on possible exposures to Human and Environmental Receptors, considering the current use(s) of the disposal site and the surrounding environment and, where applicable, any Activity and Use Limitations for the site.

(a) A condition of No Substantial Hazard to Health would exist if, for an appropriate Exposure Period, no Cumulative Receptor Cancer Risk and no Cumulative Receptor Non-cancer Risk is greater than the Cumulative Receptor Risk Limits specified at 310 CMR 40.0993(6).

(b) The period of exposure to be considered shall be equal to or greater than the time from Notification to the date that the Substantial Hazard evaluation is conducted, plus five years.

(c) A quantitative evaluation of human health risk is not required if there is no current exposure to oil and/or hazardous material at the disposal site.

(2) The focus of an Ecological Substantial Hazard Evaluation shall be on any environmental resource areas, such as wetlands, aquatic and terrestrial habitats, and fisheries, that exist at a site. A condition of No Substantial Hazard to the Environment would exist if steps have been taken to eliminate or mitigate any of the following conditions affecting an environmental resource at a site:

(a) Evidence of stressed biota attributable to the release at the disposal site, including, without limitation, fish and wildlife kills or abiotic conditions;

(b) The visible presence of oil, tar or other non-aqueous phase hazardous material in soil within three feet of the ground surface over an area equal to or greater than two acres, or over an area equal to or greater than 1000 square feet in sediment within one foot of the sediment surface;

(c) Continuing discharge of contaminated ground water to surface water where the levels of the oil or hazardous material attributable to the release already exceed Massachusetts Surface Water standards;

(d) Continuing discharge of contaminated ground water to surface water where surface water and/or sediment concentrations of Oil and/or Hazardous Material attributable to the release already pose a significant risk;

(e) Migration of oil or hazardous material to additional environmental media or resource area where resultant exposures would have the potential to pose a significant risk of harm in the future; or

(f) Ecological risk or harm such that recovery would be substantially more difficult or would require more time if conditions were to remain unremediated for even a short period of time.

(3) No assessment of Substantial Hazard is required if a condition of No Significant Risk exists and the site is eligible for a Class A or Class B Response Action Outcome.

40.0960: Characterization of Risk to Safety

(1) The risk of harm to safety shall be characterized based on the data collected pursuant to the response action being performed and the site, receptor, and exposure information identified in 310 CMR 40.0904 through 40.0933.

(2) The risk of harm to safety shall be characterized by comparing current and reasonably foreseeable conditions at the disposal site and in the surrounding environment to applicable or suitably analogous safety standards.

(3) A level of no significant risk to safety exists or has been achieved if the conditions at the disposal site which are related to a release of oil and/or hazardous material do not currently and will not in the foreseeable future pose a threat of physical harm or bodily injury to people. Such release-related conditions may include, but are not limited to:

(a) the presence of rusted or corroded drums or containers, open pits, lagoons or other dangerous structures;

(b) any threat of fire or explosion, including the presence of explosive vapors resulting from a release of oil and/or hazardous material; and

(c) any uncontained materials which exhibit the characteristics of corrosivity, reactivity or flammability described at 310 CMR 40.0347.

(4) The documentation of the Risk Characterization shall clearly state whether or not a condition of no significant risk of harm to safety exists or has been achieved at the disposal site.

40.0970: Method 1 Risk Characterization

40.0971: Applicability of Method 1

(1) Method 1 may be used to characterize the risk of harm to health, public welfare and the environment at disposal sites where assessments conducted in accordance with 310 CMR 40.0000 have determined that the presence of oil and/or hazardous material is limited to soil and/or ground water.

(2) If contamination is present in one or more environmental media other than soil or ground water, Method 1 shall not be used, except as described in 310 CMR 40.0942(1)(b). Persistent odors in ambient or indoor air resulting from a release of oil and/or hazardous material to the environment shall prohibit the use of Method 1, except as described in 310 CMR 40.0942(1)(b)1.

(3) If oil or hazardous material that are known to bioaccumulate are present within two feet of the ground surface, and Environmental Receptors have been identified pursuant to 310 CMR 40.0922, then Method 1 shall not be used, except as described in 310 CMR 40.0942(1)(c).

(4) The documentation of the Risk Characterization shall affirm and document the applicability of Method 1 to the disposal site.

(5) A Method 1 Risk Characterization shall be conducted in combination with a separate characterization of the risk of harm to safety, as described in 310 CMR 40.0960.

40.0972: General Approach to Method 1.

A Method 1 Risk Characterization compares the conditions at the disposal site to promulgated MCP Method 1 Standards. Each list of ground water and soil standards has been developed by the Department considering a defined set of exposures considered to be a conservative estimate of the potential exposures at most sites. The exposures assumed by the Department correspond to the ground water and soil categories described in 310 CMR 40.0932 and 40.0933. The Exposure Points and Exposure Point Concentrations shall be identified in a manner consistent with those categories, such that the concentrations of oil and/or hazardous material detected in soil and ground water shall be compared directly to the MCP Method 1 Standards.

40.0973: Method 1 Risk Characterization

Under Method 1, the risk of harm to health, public welfare and the environment shall be characterized as follows:

(1) The Method 1 Risk Characterization shall evaluate each current and reasonably foreseeable Site Activity and Use identified pursuant to 310 CMR 40.0923.

(2) The ground water and soil categories determined for the site in 310 CMR 40.0932 and 40.0933 shall be identified and documented.

(3) The Exposure Point(s) in ground water and soil for all current and reasonably foreseeable Site Activities and Uses shall be identified and documented as described in 310 CMR 40.0924.

(4) The MCP Method 1 Standards assume exposure to the concentrations of oil and/or hazardous material in the soil and ground water under current or foreseeable future conditions. For the Exposure Point Concentrations to be directly comparable to the MCP Method 1 Standards, they shall:

(a) be determined for each oil and/or hazardous material at each Exposure Point as described in 310 CMR 40.0926; and

(b) be representative of the actual concentration of oil and/or hazardous material at that Exposure Point, unmodified by other exposure assumptions.

(5) The applicable MCP Method 1 Ground Water and Soil Standards shall be identified as described in 310 CMR 40.0974 and 40.0975, and listed in the documentation of the Risk Characterization.

(6) The Exposure Point Concentrations identified in 310 CMR 40.0973(4) shall be compared to all applicable MCP Method 1 Standards identified in 310 CMR 40.0973(5).

(7) A condition of no significant risk of harm to health, safety, public welfare and the environment exists if no Exposure Point Concentration is greater than the applicable MCP Method 1 Soil or Ground Water Standard. If the Method 1 Soil or Ground Water Standard for Total Petroleum Hydrocarbon is exceeded, a condition of No Significant Risk shall still be considered to exist if the Exposure Point Concentrations of the Aliphatic and Aromatic Hydrocarbon Fractions comprising the TPH are less than or equal to the applicable Method 1 Soil and Ground Water Standards.

(8) The documentation of the Method 1 Risk Characterization shall clearly state whether or not a condition of no significant risk of harm to health, public welfare and the environment exists or has been achieved at the disposal site.

40.0974: Identification of Applicable Ground Water Standards in Method 1

(1) The ground water categories (GW-1, GW-2 and/or GW-3) identified for the disposal site per 310 CMR 40.0932 shall determine which column(s) of numerical standards listed in Table 1 are applicable to the ground water. If multiple categories apply to the ground water at the disposal site, the lowest of the applicable MCP Method 1 Ground Water Standards shall be used to characterize the risk of harm posed by the oil and/or hazardous material at the disposal site. The applicability of ground water standards is independent of the classification of the soil at the disposal site.

(2) Table 1 lists the potentially applicable MCP Method 1 Ground Water Standards.

40.0975: Identification of Applicable Soil Standards in Method 1

The MCP Method 1 Soil Standards consider both the potential risk of harm resulting from direct exposure to the oil and/or hazardous material in the soil and the potential impacts on the ground water at the disposal site. The applicability of a specific numerical Standard is thus a function of both the soil and the ground water category identified:

(1) The category of soil (S-1, S-2, or S-3) at each Exposure Point determines which one of the three tables of MCP Method 1 Soil Standards is applicable.

(2) The category of ground water (GW-1, GW-2, and/or GW-3) at or near each Exposure Point determines which column of the applicable MCP Method 1 Soil Standards table are relevant to the soil at the Exposure Point. If more than one ground water category is applicable at the disposal site, then multiple MCP Method 1 Soil Standards may be applicable to the soil of interest, and the lowest of those identified standards shall be selected to characterize the risk of harm.

(3) The MCP Method 1 Soil Standards listed in Table 2 in 310 CMR 40.0975(6)(a) are applicable to soil determined to be category S-1.

(4) The MCP Method 1 Soil Standards listed in Table 3 in 310 CMR 40.0975(6)(b) are applicable to soil determined to be category S-2.

(5) The MCP Method 1 Soil Standards listed in Table 4 in 310 CMR 40.0975(6)(c) are applicable to soil determined to be category S-3.

(6) Tables 2, 3 and 4 list the potentially applicable MCP Method 1 Soil Standards.

40.0980: Method 2 Risk Characterization

40.0981 Applicability of Method 2

Method 2 may be used to characterize the risk of harm to health, public welfare and the environment at disposal sites where site investigations conducted in accordance with 310 CMR 40.0000 have determined that the release of oil and/or hazardous material is limited to soil and/or ground water. If contamination is present in one or more environmental media other than soil or ground water, Method 2 shall not be used, except as described in 310 CMR 40.0942(2). A Method 2 Risk Characterization shall be conducted in combination with a separate characterization of the risk of harm to safety, as described in 310 CMR 40.0960.

40.0982 General Approach to Method 2

A Method 2 Risk Characterization supplements and modifies the MCP Method 1 Standards with site-and chemical-specific information. For the purposes of 310 cmr 40.0000, "MCP Method 2 Standards" shall refer to the MCP Method 1 Standards which have been modified to address site-specific conditions as described in 310 cmr 40.0982. Site conditions are then compared to such MCP Method 2 Standards, in the same manner that MCP Method 1 Standards are used under 310 CMR 40.0973, to characterize the risk of harm to health, public welfare and the environment.

(1) MCP Method 1 GW-1 Standards shall not be modified in Method 2. These standards are listed in 310 CMR 40.0974(2).

(2) The component of the MCP Method 1 Soil Standards which is protective of direct contact exposures to the soil shall not be modified in Method 2. These standards are listed in 310 CMR 40.0985(6).

(3) The following information may be used under Method 2 to modify the Method 1 Standards:

(a) MCP Method 2 Ground Water and Soil Standards may be developed for chemicals for which MCP Method 1 Standards have not been promulgated by the Department. This process is described in 310 CMR 40.0983 and 40.0984.

(b) Site-specific information may be used to either modify the leaching component of the MCP Method 1 Soil Standards or to demonstrate that a contaminant will not leach to ground water. The incorporation of such site-specific information will result in MCP Method 2 Soil Standards or a determination that the leaching component of one or more Method 1 soil standard is not applicable. These site-specific modifications are described in 310 CMR 40.0985.

(c) Site-specific information may be used to either modify the MCP Method 1 GW-2 Standards, which model potential volatilization of oil and/or hazardous material to indoor air, or to demonstrate that such vapor infiltration will not occur. The incorporation of such site-specific information will result in MCP Method 2 GW-2 Standards or a determination that one or more Method 1 GW-2 standard is not applicable at this site. These site-specific modifications are described in 310 CMR 40.0986.

(d) Site-specific information may be used to either modify the MCP Method 1 GW-3 Standards, which are set to be protective of potential discharges of oil and/or hazardous material to surface water, or to demonstrate that such discharges will not occur. The incorporation of such site-specific information will result in MCP Method 2 GW-3 Standards or a determination that one or more Method 1 GW-3 standard is not applicable. These site-specific modifications are described in 310 CMR 40.0987.

(4) If the modification of a MCP Method 1 GW-2 or GW-3 Standard results in a concentration of an oil and/or hazardous material greater than the Upper Concentration Limit in Ground Water listed in 310 CMR 40.0996(5), then the Upper Concentration Limit for that chemical shall be used to characterize the risk of harm to health, public welfare and the environment in Method 2.

(5) MCP Method 1 Standards may be used in combination with one or more MCP Method 2 Standards. A Risk Characterization which uses a combination of MCP Method 1 and 2 Standards shall be considered a Method 2 Risk Characterization.

(6) The MCP Method 2 Standards developed and used or relied upon by the LSP shall be listed and suitably documented.

(7) The Department may develop and publish sets of chemical-specific concentrations which, for specific types of disposal sites, will demonstrably meet the Risk Characterization requirements described at 40.0990. Such concentrations may be used at the RP's, PRP's or Other Person's option to characterize risk at a disposal site, and the use of these sets of concentrations shall be considered a Method 2 Risk Characterization.

40.0983: Derivation of Additional Method 1 Ground Water Standards for Use in Method 2.

If an MCP Method 1 Ground Water Standard has not been promulgated by the Department, the LSP may develop an MCP Method 2 Standard for that oil and/or hazardous material on the basis of the following assumptions and procedures:

(1) A site-specific background concentration in ground water shall be identified for the oil and/or hazardous material.

(2) GW-1 Standards shall be calculated as follows:

(a) Based on non-cancer health risk, a concentration in drinking water of the oil and/or hazardous associated with 20% of a Reference Dose shall be identified using the following equation:

[OHM] =(RfD x 7,000)/RAForal

Where: [OHM] = the concentration of oil and/or hazardous material being derived, in units: μg/L (ppb)

RfD = the Reference Dose, in units: mg/(kg * d)

7,000 = (0.2 * 70 kg * 1000 μg/mg)/(2 L/d)

RAForal = the Relative Absorption Factor applicable for oral exposures dimensionless.

(b) A concentration of the oil and/or hazardous material associated with an Excess Lifetime Cancer Risk equal to one-in-one million shall be identified using the following equation:

[OHM] = 0.035/(CSF * RAForal)

Where: [OHM] = the concentration of oil and/or hazardous material being derived, in units: μg/L (ppb)

0.035 = (10-6 * 70 kg * 103 μg/mg)/(2 L/d)

CSF = the oral Carcinogenic Slope Factor, in units: (mg/(kg * d))-1

RAForal = the Relative Absorption Factor applicable for oral exposure, dimensionless.

(c) The concentration in water of the oil and/or hazardous material at which 50% of the population can detect its odor is identified, if available.

(d) The lowest non-zero concentration estimated in 310 CMR 40.0983(2)(a), (b), and (c) is identified as the risk-based concentration for the oil and/or hazardous material of concern;

(e) The site-specific ground water background concentration identified for the oil and/or hazardous material in 310 CMR 40.0983(1) is considered;

(f) The Practical Quantitation Limit (PQL) applicable to the oil and/or hazardous material using an appropriately sensitive analytical method for quantifying the concentration of the oil and/or hazardous material in water shall be identified.

(g) The highest of the three concentrations identified in 310 CMR 40.0983(2)(d), (e) and (f) is adopted as the MCP Method 2 GW-1 Standard for that oil and/or hazardous material.

(3) GW-2 Standards shall be determined as follows:

(a) A risk-based indoor air concentration shall be identified by choosing the lower non-zero value from the following:

1. A concentration equal to 20% of a Reference Concentration (RfC) or an analogous allowable concentration is identified when sufficient information exists.

2. An indoor air concentration associated with an Excess Lifetime Cancer Risk of one-in-one million, using the following equation, when sufficient information exists:

[OHM]air = 10-6 / URair

Where:

[OHM]air = The calculated indoor air concentration. In units of: μg/cubic meter.

10-6 = A one-in-one-million Excess Lifetime Cancer Risk (dimensionless)

URair = The Unit Risk in air for the chemical. In units of: (μg/cubic meter)-1

3. The concentration in air of the oil and/or hazardous material at which 50% of the population can detect its odor is identified, if available.

(b) A background indoor air concentration for the chemical shall be identified and compared to the risk-based concentration calculated in 310 CMR 40.0983(2)(a). The higher of the two values shall be chosen as the target indoor air concentration.

(c) A source attenuation factor, α, shall be determined for the oil and/or hazardous material, assuming conservative site characteristics, including: a depth to ground water of three meters (nine feet), a basement floor both two meters (six feet) below grade and one meter (three feet) above the ground water table, a soil water-filled porosity equal to 0.06 cm3/cm3, and sandy-loam soil between the ground water and the basement.

(d) A concentration in ground water for the oil and/or hazardous material shall be calculated using the following equation:

[OHM]gw = [OHM]air / (α * H * C)

Where:

[OHM]gw = The calculated GW-2 Standard, in units of: μg/liter (ppb).

[OHM]air = The target indoor air concentration identified in 310 CMR 40.0983(2)(b). In units of μg/cubic meter.

α = A source attenuation factor as determined at 310 CMR 40.083(2)(c). Dimensionless.

d = An applied dilution factor equal to 0.1. Dimensionless.

H = The Henry's Law Constant for the chemical. Dimensionless.

C = Units Conversion Factor, 1000 l/m3.

(e) The site specific ground water background concentration shall be identified for the oil and/or hazardous material in 310 CMR 40.0983(1) is considered;

(f) the Practical Quantitation Limit (PQL) applicable to the oil and/or hazardous material using an appropriately sensitive analytical method for quantifying the concentration of the oil and/or hazardous material in water shall be identified;

(g) the highest of the three concentrations identified in 310 CMR 40.0983(2)(d), (e) and (f) shall be adopted as the MCP Method 2 GW-2 Standard for that oil and/or hazardous material.

(4) GW-3 Standards shall be determined as follows:

(a) The lowest ecologically-based Water Quality Criterion for the oil and/or hazardous material of concern shall be identified (i.e., the Fresh Water Chronic Criterion, the Fresh Water Acute Criterion, the Marine Chronic Criterion, or the Marine Acute Criterion). If no such criterion exists, an analogous value from the scientific literature may be proposed.

(b) The concentration (in μg/liter, or ppb) identified in 310 CMR 40.0983(4)(a) shall be multiplied by a factor of ten.

(c) The concentration identified in 310 CMR 40.0983(4)(b) shall be multiplied by:

1. a factor of 2.5 if the Koc value for the oil or hazardous material of concern is less than 1,000;

2. a factor of 25 if the Koc value for the oil or hazardous material of concern is greater than or equal to 1,000 but less than 100,000; or

3. a factor of 100 if the Koc value for the oil or hazardous material of concern is greater than or equal to 100,000.

(d) The resulting concentration (in μg/L, or ppb) shall be the MCP Method 2 GW-3 Standard for the oil and/or hazardous material of concern.

(5) Any of the MCP Method 2 ground water standards calculated in 310 CMR 40.0983(2) through (4) shall be adjusted to a ceiling concentration of 50,000 μg/liter (ppb) if the calculated value is greater than 50,000 μg/liter (ppb);

40.0984: Derivation of Additional Method 1 Soil Standards for Use in Method 2.

If an MCP Method 1 Soil Standard has not been promulgated by the Department, the RP, PRP or Other Person may develop an MCP Method 2 Standard for that oil and/or hazardous material on the basis of the following assumptions and procedures:

(1) A site-specific background concentration in soil shall be identified for the oil and/or hazardous material.

(2) Based upon non-cancer health risk, a concentration of the oil and/or hazardous material associated with 20% of a Reference Dose shall be identified using equations specific to each soil category.

Where: [OHM] = the concentration of oil and/or hazardous material being derived, in units: mg/kg (ppm)

RfD = the chronic or subchronic Reference Dose for the chemical, in units: mg/(kg x day)

RAForal = the Relative Absorption Factor applicable for oral exposures, dimensionless

RAFdermal = the Relative Absorption Factor applicable for dermal exposures, dimensionless

C = 106 mg/kg conversion factor

0.2 = 20% source allocation factor

Other numerical

values = Average Daily Exposure to the soil of concern by the oral or dermal pathway. In units: mgsoil/(Kgbw x day)

(a) S-1 Standards: The concentration of the oil and/or hazardous material shall be derived using the following equation:

[OHM] = (RfDchronic x 0.2 x C)/((RAForal x 2.4) + (RAFdermal x 21))

(b) S-2 Standards: The concentration of the oil and/or hazardous material is derived using the lower result from the following equations:

[OHM] = (RfDchronic x 0.2 x C)/((RAForal x 0.27) + (RAFdermal x 0.5)); and

[OHM] = (RfDsubchronic x 0.2 x C)/((RAForal x 1.3) + (RAFdermal x 12.4))

(c) S-3 Standards: the concentration of the oil and/or hazardous material is derived using the following equation:

[OHM] = (RfDsubchronic x 0.2 x C)/((RAForal x 1.3) + (RAFdermal x 12.4))

(3) A concentration of the oil and/or hazardous material associated with an Excess Lifetime Cancer Risk equal to one-in-one million shall be identified using equations specific to each soil category;

Where: [OHM] = the concentration of oil and/or hazardous material being derived, in units: mg/kg (ppm)

CSF = the oral Carcinogenic Slope Factor, in units: (mg/(kg x day))-1

RAForal = the Relative Absorption Factor applicable for oral exposures, dimensionless

RAFdermal = the Relative Absorption Factor applicable for dermal exposures, dimensionless

C = 106 mg/kg conversion factor

Other numerical

values = Lifetime Average Daily Exposure to the soil of concern by the oral or dermal pathway. In units: mgsoil/(Kgbw x day)

(a) S-1 Standards: The concentration of the oil and/or hazardous material shall be derived using the following equation:

[OHM] = (1x10-6 x C)/(CSF x ((RAForal x 0.38) + (RAFdermal x 4.1)))

(b) S-2 Standards: the concentration of the oil and/or hazardous material shall be derived using the following equation:

[OHM] = (1x10-6 x C)/(CSF x ((RAForal x 0.11) + (RAFdermal x 0.19)))

(c) S-3 Standards: The concentration of the oil and/or hazardous material shall be derived using the following equation:

[OHM] = (1x10-6 x C)/(CSF x ((RAForal x 0.01) + (RAFdermal x 0.09)))

(4) Considering the category determined for the ground water at the disposal site per 310 CMR 40.0932 and an acceptable leaching model or test method as discussed in 310 CMR 40.0985, a concentration in soil which will not result in ground water concentrations of the oil and/or hazardous material greater than the applicable MCP Method 2 ground water standard derived in 310 CMR 40.0983 shall be identified.

(5) For each combination of soil and ground water categories, the lowest non-zero concentration estimated in 310 CMR 40.0984(2) through (4) shall be the risk-based concentration for the oil and/or hazardous material of concern.

(6) The site-specific background concentration identified in 310 CMR 40.0984(1) shall be considered.

(7) The Practical Quantitation Limit (PQL) applicable to the oil and/or hazardous material using an appropriately sensitive analytical method for quantifying the concentration of the chemical in soil shall be identified.

(8) For each combination of the soil and ground water categories, the highest of the three concentrations identified in 310 CMR 40.0984(5) through (7) shall be adopted as the MCP Method 2 soil standard for that combination of soil and ground water categories.

(9) MCP Method 2 soil standards identified in 40.0984(8) shall be adjusted to a ceiling concentration if the calculated concentration is greater than the ceiling concentration. The ceiling concentration shall be based upon the "Odor Index" of the chemical, defined for the purposes of these regulations to be the ratio of the vapor pressure of the chemical and the 50% odor recognition level (odor threshold) for the chemical:

Odor Index = VP ¸ ORL50%

Where: VP = The vapor pressure of the oil and/or hazardous material, in units of TORR, measured at temperatures between 20_ and 30_ Celsius.

ORL50% = The concentration of the oil and/or hazardous material at which 50% of the general population would recognize its odor. In units: parts per million (ppm).

(a) S-1 Standards:

1. Chemicals having an Odor Index greater than or equal to 100 shall be assigned a ceiling concentration of 100 mg/kg (ppm).

2. Chemicals having an Odor Index greater than or equal to one but less than 100 shall be assigned a ceiling concentration of 500 mg/kg (ppm).

3. For chemicals having an Odor Index less than one or for which there is insufficient data to calculate an Odor Index, the assigned ceiling concentration shall be 1,000 mg/kg (ppm).

(b) S-2 Standards:

1. Chemicals having an Odor Index greater than or equal to 100 shall be assigned a ceiling concentration of 500 mg/kg (ppm).

2. Chemicals having an Odor Index greater than or equal to one but less than 100 shall be assigned a ceiling concentration of 1,000 mg/kg (ppm).

3. For chemicals having an Odor Index less than one or for which there is insufficient data to calculate an Odor Index, the assigned ceiling concentration shall be 2,500 mg/kg (ppm).

(c) S-3 Standards:

1. Chemicals having an Odor Index greater than or equal to 100 shall be assigned a ceiling concentration of 1,000 mg/kg (ppm).

2. Chemicals having an Odor Index greater than or equal to one but less than 100 shall be assigned a ceiling concentration of 2,500 mg/kg (ppm).

3. For chemicals having an Odor Index less than one or for which there is insufficient data to calculate an Odor Index, the assigned ceiling concentration shall be 5,000 mg/kg (ppm).

40.0985: Determination of Method 2 Soil Standards Considering Leaching Potential

MCP Method 1 Soil Standards consider both the risks associated with direct contact with the contaminated soil and the potential for the oil and/or hazardous material to leach to ground water. The leaching component of the MCP Method 1 Soil Standards can be modified or eliminated in Method 2 considering site-specific information. The direct contact-exposure component of the standard shall not be adjusted in this Method.

(1) The development of alternative leaching-based soil concentrations or the determination that leaching-based concentrations are not applicable shall be based upon information which is scientifically justified and completely documented.

(2) When developing alternative leaching-based concentrations in soil, alternative values shall be developed for each oil and hazardous material and for each applicable ground water category. Demonstrations that the leaching-based component of the Method 1 soil standards is not applicable may be made on a chemical-by-chemical basis or for the site as a whole, depending upon the information relevant to that determination.

(3) The following methods may be used to demonstrate that the concentrations of oil and/or hazardous material in soil at the disposal site now and in the foreseeable future will result in compliance with all applicable MCP Method 1 or 2 Ground Water Standards:

(a) transport and fate modeling that incorporates site-specific information on source mass and subsurface hydrogeological conditions; and/or

(b) laboratory tests that demonstrate, under site conditions, the oil and/or hazardous material in the soil will not leach to ground water at levels which exceed the applicable MCP Method 1 or 2 Ground Water Standards.

(4) For each combination of soil category (S-1, S-2, and S-3) and ground water category (GW-1, GW-2, and GW-3), the lower of the following is the applicable MCP Method 2 Soil Standard for the oil and/or hazardous material:

(a) The leaching-based soil concentration identified in 310 CMR 40.0985(2) specific to the ground water category, and

(b) The direct contact exposure-based concentration specific to the soil category, listed in Table 5 in 310 CMR 40.0985(6). The direct contact standard is applicable when it is determined that the leaching-based component of the Method 1 standard is not applicable per 310 CMR 40.0985(2).

(5) Ground water monitoring shall demonstrate that residual soil contamination is not and will not result in ground water concentrations greater than the applicable MCP Method 1 or 2 Ground Water Standards. The duration of required monitoring shall depend on the source mass, the mobility of the oil and/or hazardous material, and subsurface conditions.

(6) Table 5 lists the Direct Contact Exposure-Based Soil Concentrations.

40.0986: Determination of Method 2 GW-2 Standards.

(1) MCP Method 1 GW-2 Standards consider the potential for oil and/or hazardous material to volatilize from the ground water and migrate to indoor air. These standards may be modified under Method 2, or a determination may be made that one or more GW-2 standards are not applicable, based upon site-specific conditions. Modifications of a standard will result in a proposed MCP Method 2 GW-2 Standard. Proposed Method 2 standards or the determination that one or more GW-2 standards are not applicable shall be scientifically justified and sufficiently documented to demonstrate that the Response Action Performance Standard, described in 310 CMR 40.0191 has been met.

(2) An MCP Method 2 GW-2 Standard shall be protective of migration of oil and/or hazardous material into indoor air. The presence of oil and/or hazardous material in the ground water at the proposed MCP Method 2 GW-2 Standard below or near a building shall not result in indoor air concentrations which pose a significant risk of harm to health, public welfare or the environment. The MCP Method 2 GW-2 Standard may be greater or less than the corresponding MCP Method 1 GW-2 Standard, or it may be determined that the Method 1 Standard is not applicable, based upon site-specific conditions. The development of such standards shall be documented by:

(a) transport and fate modeling that incorporates site-specific information on source, hydrogeological, and building conditions, and which demonstrates that the oil and/or hazardous material in the soil will not infiltrate to indoor air and result in significant risk of harm to health, public welfare or the environment; and/or

(b) soil gas characterization data, indoor air characterization data, and other information and data resulting from field investigation conducted at and proximate to the disposal site.

40.0987: Determination of MCP Method 2 GW-3 Standards.

(1) MCP Method 1 GW-3 Standards consider potential migration of oil and/or hazardous material to surface water. These standards may be modified under Method 2 based upon site-specific conditions to develop MCP Method 2 GW-3 Standards or it may be determined that a discharge to surface water will not occur. The proposed Method 2 modification shall be scientifically justified and sufficiently documented to demonstrate that the Response Action Performance Standard, described in 310 CMR 40.0191, has been met.

(2) An MCP Method 2 GW-3 standard or determination shall be protective of migration of oil and/or hazardous material into surface waters and wetlands. The presence of an oil and/or hazardous material in the ground water must not result in concentrations in a surface water or wetland which would pose a significant risk of harm to health, public welfare or the environment. The MCP Method 2 GW-3 Standard may be greater or less than the corresponding MCP Method 1 GW-3 Standard, or it may be determined that the Method 1 GW-3 standard is not applicable, considering site-specific conditions. The development of such standards or such a determination shall be documented by:

(a) transport and fate modeling that incorporates site-specific information on the source and subsurface hydrological conditions, and which demonstrates that the release will not result in concentrations of oil and/or hazardous material in the receiving surface water which exceed any applicable or suitably analogous standards described in 310 CMR 40.0993(3), and which do not otherwise result in a significant risk of harm to health, safety, public welfare or the environment; and/or

(b) long-term ground water monitoring which demonstrates that the release will not result in concentrations of oil and/or hazardous material in the receiving surface water which exceed any applicable or suitably analogous standards described in 310 CMR 40.0993(3), and which do not otherwise result in a significant risk of harm to health, safety, public welfare or the environment. The duration of required monitoring would depend on the source mass, the mobility of the oil and/or hazardous material, and subsurface conditions.

40.0988: Method 2 Risk Characterization.

(1) When conducting a Method 2 Risk Characterization, the risk of harm to health, public welfare and the environment shall be characterized using the methodology described in 310 CMR 40.0970 (Risk Characterization Method 1), and any applicable MCP Method 1 Standards in combination with one or more MCP Method 2 Standards identified pursuant to 310 CMR 40.0980.

(2) A condition of no significant risk of harm to health, safety, public welfare and the environment exists if no Exposure Point Concentration is greater than the applicable MCP Method 1 and Method 2 Soil or Ground Water Standard. If the Method 1 or Method 2 Soil or Ground Water Standard for Total Petroleum Hydrocarbon is exceeded, a condition of No Significant Risk shall still be considered to exist if the Exposure Point Concentrations of the Aliphatic and Aromatic Hydrocarbon Fractions comprising the TPH are less than or equal to the applicable Method 1 or Method 2 Soil and Ground Water Standards.

(3) The documentation of the Method 2 Risk Characterization shall clearly state whether or not a condition of no significant risk of harm to health, public welfare or the environment exists or has been achieved at the disposal site.

40.0990: Risk Characterization Method 3

40.0991 Applicability of Method 3

Method 3 may be used to characterize the risk of harm to health, public welfare and the environment for any disposal site. In a Method 3 Risk Characterization, the risks of harm to health, public welfare and the environment are evaluated separately.

40.0992: General Approach to Method 3

Method 3 relies upon detailed information about the site, the oil and/or hazardous material, and potential exposures to Human and Environmental Receptors under all current and reasonably foreseeable Site Activities and Uses to characterize the risk of harm. The scope and level of effort of the Method 3 Risk Characterization shall reflect the site-specific nature of this Method, and the information used to characterize the risk shall be sufficiently documented to demonstrate that the Response Action Performance Standard, described in 310 CMR 40.0191, has been met.

(1) The Method 3 Risk Characterization shall be performed in a manner consistent with scientifically acceptable risk assessment practices, and consider guidance published by the Department and EPA.

(2) In performing a Method 3 Risk Characterization, the objective shall be to provide a conservative estimate of the impact that the oil and/or hazardous material may have on the Human and Environmental Receptors at the disposal site and in the surrounding environment.

(3) This Risk Characterization process makes use of existing standards, Upper Concentration Limits in Ground Water and Soil, quantitative estimates of cancer and noncancer health risks, and both quantitative and qualitative evaluations of risk to public welfare and the environment to determine the need for a remedial action or to demonstrate that a condition of No Significant Risk exists or has been achieved.

(a) The Method 3 characterization of the risk of harm to human health is described in 310 CMR 40.0993.

(b) The Method 3 characterization of the risk of harm to public welfare is described in 310 CMR 40.0994.

(c) The Method 3 characterization of the risk of harm to the environment is described in 310 CMR 40.0995.

(d) The list of Upper Concentration Limits in Ground Water and Soil is in 310 CMR 40.0996(5).

(4) The risk of harm to safety shall also be characterized, as described in 310 CMR 40.0960.

40.0993: Method 3 Human Health Risk Characterization

Under Method 3, the risk of harm to human health shall be characterized for all current and reasonably foreseeable Site Activities and Uses identified in 310 CMR 40.0923, as follows:

(1) The site, receptor and exposure information described in 310 CMR 40.0901 though 40.0920 shall be identified and documented.

(2) The ground water and soil categories applicable to the disposal site shall be identified and documented, as described in 310 CMR 40.0930. The ground water and soil categories shall be considered as general indicators of exposure potential in a Method 3 evaluation.

(3) All applicable or suitably analogous health standards shall be identified in the documentation of the Method 3 Risk Characterization. The MCP Method 1 Ground Water and Soil Standards listed in 310 CMR 40.0970 are not considered applicable or suitably analogous, as those standards represent an alternative approach to Method 3. The list of potentially applicable or suitably analogous standards includes, but is not limited to:

(a) Massachusetts Drinking Water Quality Standards promulgated in 310 CMR 22.00, which are considered applicable to all category GW-1 ground water;

(b) Massachusetts Air Quality Standards promulgated in 310 CMR 6.00; and

(c) Massachusetts Surface Water Quality Standards promulgated in 314 CMR 4.00.

(4) The frequency, duration and intensity of exposure to each oil and/or hazardous material at the disposal site for each receptor at each Exposure Point shall be determined and documented, considering the current and reasonably foreseeable Site Activities and Uses identified for the disposal site. The magnitude of each receptor's total exposure to the oil and/or hazardous material at the disposal site is calculated in a manner which provides a conservative estimate of the potential exposures. Assessments conducted using a probabilistic analysis shall identify the 95th percentile estimate of each receptor's potential exposure.

(5) For each identified Human Receptor, cumulative cancer risks and cumulative non-cancer risks shall be calculated.

(a) Chemical-specific toxicity information used to estimate the cancer and non-cancer risks shall be identified and documented, and the selection of this information shall take into account guidance published by the Department. Primary consideration shall be given to information developed by the Massachusetts Department of Environmental Protection for the purpose of conducting such risk assessments. Examples of such toxicity information include:

1. Reference Doses and Reference Concentrations; and

2. Carcinogenic Slope Factors and Unit Risks values.

(b) For receptors who may be exposed to mixtures of oil and/or hazardous material, or through multiple Exposure Pathways at the disposal site, the cumulative risk shall reflect those exposures. Risk estimates are presumed to be additive unless an alternative mechanism is demonstrated to be appropriate.

(c) Risk calculations performed using a probabilistic analysis shall identify the cumulative cancer and non-cancer risks associated with the 95th percentile estimate of exposure.

(6) The Cumulative Receptor Cancer Risks shall be compared to a Cumulative Cancer Risk Limit which is an Excess Lifetime Cancer Risk equal to one-in-one hundred thousand. Cumulative Receptor Non-cancer Risks shall be compared to a Cumulative Non-cancer Risk Limit which is a Hazard Index equal to one. Estimated Exposure Point Concentrations shall be compared to any applicable or suitably analogous standards.

(7) A condition of no significant risk of harm to human health exists or has been achieved if:

(a) no Exposure Point Concentration of oil and/or hazardous material is greater than an applicable or suitably analogous public health standard;

(b) no Cumulative Receptor Cancer Risk calculated is greater than the Cumulative Cancer Risk Limit; and

(c) no Cumulative Receptor Non-cancer Risk is greater than the Cumulative Receptor Non-cancer Risk Limit.

(8) The documentation of the Method 3 human health Risk Characterization shall clearly state whether or not a condition of no significant risk of harm to human health exists or has been achieved, based upon the criteria described in 310 CMR 40.0993(7).

(9) All mathematical equations used to calculate cumulative receptor cancer and non-cancer risks shall be clearly presented and documented.

40.0994: Method 3 Public Welfare Risk Characterization

Purpose. There are two purposes for conducting a characterization of risk to public welfare: (a) to identify and evaluate nuisance conditions which may be localized, and (b) to identify and evaluate significant community effects. The characterization of risk to public welfare shall consider effects which are or may result from the presence of residual contamination or the implementation of a proposed remedial alternative.

The characterization of risk to public welfare shall be conducted for all current and reasonably foreseeable Site Activities and Uses identified in 310 CMR 40.0923, as follows:

(1) The characterization of the risk of harm to public welfare shall consider the site, receptor, and exposure information identified in 310 CMR 40.0901 through 40.0930, as well as data collected pursuant to the response action(s) being performed.

(2) the characterization of the risk to public welfare shall, in addition to those factors identified in 310 CMR 40.0994(1), also consider such factors as the existence of nuisance conditions, loss of active or passive property use(s), and any non-pecuniary effects not otherwise considered in the characterization of risk of harm to health, safety, and the environment but which may accrue due to the degradation of public resources directly attributable to the release or threat of release of oil and/or hazardous material or the remedial alternative.

(3) The risk of harm to public welfare shall also be characterized by comparing the concentration of each oil or hazardous material to the Upper Concentration Limits in Soil and Ground Water, as described at 310 CMR 40.0996.

(4) A level of no significant risk of harm to public welfare exists or has been achieved if:

(a) No nuisance conditions exist or will result from the release or threat of release of oil or hazardous material, or the remedial alternative, including:

1. The breathing zone of ambient and indoor air are currently and will, in the reasonably foreseeable future, remain free from persistent, noxious odors,

2. There is accessible drinking water that is and will, in the reasonably foreseeable future, remain free from noxious taste and odors; and

3. Livestock is and will remain, in the reasonably foreseeable future, free from harmful effects. No specific evaluation of livestock is required if it is reasonable to conclude that the human health and environmental risk characterizations conducted for the site are also protective of livestock exposures.

(b) No community that is currently affected and/or community for which it is reasonably foreseeable to conclude that it could be affected by the release experiences significant adverse impacts as set forth as the factors to be considered in 40.0994(2); and

(c) The requirements of 310 CMR 40.0996 concerning the Upper Concentration Limits are met.

(5) The documentation of the Method 3 public welfare Risk Characterization shall clearly state whether or not a condition of no significant risk of harm to public welfare exists or has been achieved at the current and reasonably foreseeable Site Activities and Uses.

40.0995: Method 3 Environmental Risk Characterization

The characterization of risk of harm to the environment shall be conducted for all current and reasonably foreseeable Site Activities and Uses identified in 310 CMR 40.0923. Characterization of the risk of harm to the environment shall include an assessment of chemical data, potential contaminant migration pathways, and an evaluation of biota and habitats at and in the vicinity of the disposal site, as described in 310 CMR 40.0995(2), as well as through the application of Upper Concentration Limits, as described in 310 CMR 40.0995(5).

(1) A Method 3 characterization of the risk of harm to the environment shall be based on the site, receptor and exposure information identified in 310 CMR 40.0901 through 40.0920, as well as any relevant data collected during the response action being performed.

(2) The risk of harm to the site biota and habitats shall be characterized by evaluating ecological parameters using a two-stage approach. In Stage I, the objective is to identify and document conditions which do not warrant a Stage II Risk Characterization, either because of the absence of a potentially significant exposure pathway or because environmental harm is readily apparent and therefore additional assessment would be redundant. If a potentially significant exposure pathway is indicated by the available information per 40.0995(3)(a) and 40.0995(3)(c), then a Stage II Environmental Risk Characterization is required to characterize the risks posed by those exposures.

(a) A Stage I Environmental Screening shall be performed as described in 310 CMR 40.0995(3) for all disposal sites evaluated using Risk Characterization Method 3, and for those disposal sites evaluated using a Method 3 Environmental Risk Characterization in combination with Method 1 or Method 2 as described in 310 CMR 40.0942.

(b) Following a Stage I Environmental Screening and based upon the criteria described in 310 CMR 40.0995(3), it may be concluded that:

1. A Stage II Environmental Risk Characterization is not required because there are no complete exposure pathways that could result in potentially significant exposures, and a condition of no significant risk of harm to site biota and habitats clearly exists, or

2. A Stage II Environmental Risk Characterization is not required because, for each contaminated medium, harm is readily apparent; therefore a condition of no significant risk of harm to the site biota and habitats clearly does not exist, and a Stage II Environmental Risk Characterization would be redundant, or

3. A Stage II Environmental Risk Characterization is required because, for one or more contaminated media, there is not enough information to determine whether or not a condition of no significant risk of harm exists, and therefore those media are considered to present "potentially significant exposures".

(c) The scope and nature of the Stage II Environmental Risk Characterization shall depend on the nature of the disposal site, the Environmental Receptors affected or potentially affected, and the Stage I Environmental Screening criteria which indicated the need for the Stage II Environmental Risk Characterization.

(3) Stage I Environmental Screening. Exposures of site biota and habitats shall be characterized by the Stage I Environmental Screening as follows:

(a) Available evidence shall be evaluated to determine whether there is current or potential future exposure of Environmental Receptors to contamination at or from the disposal site. Sources of such evidence shall include historical records, site data, field observations, statements by present and past residents or employees, and any other relevant source.

1. Evidence of current or potential exposure shall include, but is not limited to:

a. Current or past visible physical evidence that oil and/or hazardous material at or from the disposal site have come to be located in surface soil, surface water, sediment or wetlands. Examples of such evidence include, without limitation, the presence of sheens from oil or hazardous material, non-aqueous phase liquids, oil, tar or other solid or semi-solid hazardous material in surface soil, surface water, sediment or wetlands;

b. Records or other evidence of current or past impacts of oil and/or hazardous material from the disposal site on wildlife, fish, shellfish or other aquatic biota. Examples of such impacts include, without limitation, fish kills and abiotic conditions;

c. Analytical data indicating the presence of oil and/or hazardous material attributable to the site in question in surface water or sediment (including wetlands);

d. The potential for the transport of oil and/or hazardous material in the ground water or surface runoff to such receptors as surface water or sediments (including wetlands) identified as Environmental Receptors; or

e. The presence of oil and/or hazardous material at the disposal site within two feet of the ground surface and the potential for such contamination to result in exposure to wildlife.

2. If no current or potential future exposure is identified, then a condition of "no significant risk of harm" to the site biota and habitats exists or has been achieved, and a Stage II Environmental Risk Characterization is not required.

(b) If any current or potential future exposure is identified, then for each such exposure, site conditions shall be evaluated to determine whether significant environmental harm is "readily apparent".

1. The following conditions shall represent "readily apparent harm" :

a. Visual evidence of stressed biota attributable to the release at the disposal site, including, without limitation, fish kills or abiotic conditions;

b. The existence of oil and/or hazardous material attributable to the disposal site in concentrations which exceed Massachusetts Surface Water Standards promulgated in 314 CMR 4.00, which include USEPA Ambient Water Quality Criteria applied pursuant to 314 CMR 4.05(5)(e).

c. Visible presence of oil, tar, or other non-aqueous phase hazardous material in soil within three feet of the ground surface over an area equal to or greater than two acres, or over an area equal to or greater than 1,000 square feet in sediment within one foot of the sediment surface.

2. If a condition of readily apparent harm exists in any environmental medium, then a condition of "no significant risk of harm" does not exist, and a Stage II Environmental Risk Characterization is not required to make that determination for that medium.

(c) Each current and potential future exposure Pathway identified in 310 CMR 40.0995(3)(a) must be evaluated to determine whether it could result in potentially significant exposure.

1. Any potential exposure identified in 40.0995(3)(a) must be considered a "potentially significant exposure" unless it can be ruled out as such using:

a. USEPA Ambient Water Quality Criteria and Massachusetts Surface Water Standards promulgated in 314 CMR 4.00;

b. environmental concentrations specifically adopted by the Department as screening criteria; or

c. site size, location, and/or landscape characteristics specifically adopted by the Department as screening criteria.

2. If, through the application of the screening criteria identified in 310 CMR 40.0995(3)(c)1., an environmental medium (such as soil, sediment or surface water) can be screened out as a source of "potentially significant exposures", then a Stage II Environmental Risk Characterization is not required for any exposure pathway for which that medium is the contaminant source.

3. If current or potential future exposures to contaminants in any media are not ruled out in Stage I Screening, those exposures are considered to be "potentially significant exposures" and a Stage II Environmental Risk Characterization is required to determine whether a condition of "no significant risk of harm" exists.

(4) Stage II Environmental Risk Characterization: A Stage II Environmental Risk Characterization shall be used to determine whether there is significant risk of environmental harm or evidence of environmental harm.

(a) The Stage II Environmental Risk Characterization shall be conducted under the supervision of an individual trained and knowledgeable in ecological studies.

(b) The Stage II Environmental Risk Characterization shall identify environmental resources associated with the disposal site, such as wetlands, aquatic and terrestrial habitat, fisheries, or rare and endangered species, and shall evaluate whether the release of oil and/or hazardous material has adversely impacted, or may adversely impact the ecological functions which support those resources.

1. The evaluation shall focus on ecological functions at the spatial scale of the disposal site.

2. The relevance of potential impacts shall be judged at the spatial scale of the disposal site (e.g., effects on subpopulations that use the site as habitat) rather than the proportional significance of the site to regional environmental resources.

(c) The Stage II Risk Characterization shall include, but is not limited to, the following steps:

1. Problem Formulation. The first phase of the assessment shall establish the goals, scope and focus of the Stage II Environmental Risk Characterization. A baseline site survey to identify biota and exposures of potential concern shall be conducted. Available scientific literature shall be used to identify potential adverse effects of concern.

a. Assessment endpoints shall be identified. The combination of assessment endpoints selected for a site must represent the ecological entities, characteristics and functions most likely to be adversely affected by the oil and/or hazardous material in each contaminated medium at the site. The assertion that the selected assessment endpoints are representative of the exposed biota on the basis of their susceptibility to harm by the contamination of concern must be justified and documented, either on a case-by-case basis or by citing DEP guidance. Assessment endpoints shall be defined in terms of ecological entities and their characteristics and functions, as follows:

i. An ecological entity refers to an organism, a species, a functional group of species, a community, an ecosystem, or a habitat.

ii. Valued characteristics include but are not limited to growth, reproduction, survival, nutrient cycling, and habitat functions, health of local populations or sub-populations and community diversity.

b. Measures of exposure shall consider the spatial and temporal distribution of oil and hazardous material, and shall represent the co-occurrence of contamination with the assessment endpoint organisms.

c. Measures of effects shall be selected for each assessment endpoint, such that the results of the measures will enable the detection of adverse effects of oil and hazardous material on the assessment endpoint. The relevance and validity of the proposed measures of effects shall be documented. Measures of effects may include, but are not limited to:

i. Comparison of environmental concentrations to ecologically based benchmarks published in the scientific literature, technical literature or government documents;

ii. toxicity data reported in scientific literature;

iii. site-specific toxicity tests to evaluate the effects of contaminated media on survival, growth, and/or reproduction of the target organisms;

iv. quantitative or semi-quantitative field surveys to evaluate adverse impacts on receptor subpopulations or communities exposed to oil or hazardous materials at or from the site; and

v. field experiments.

2. Analysis. The second phase of the risk assessment shall characterize any actual and potential environmental exposures and associated ecological effects.

3. Risk Characterization. In the final phase of the risk assessment, the results of the environmental exposure and effects analysis shall be used to evaluate the likelihood of adverse ecological effects. The documentation of the Risk Characterization shall include a summary of assumptions, scientific uncertainties, strengths and weaknesses of the analyses, and justification of conclusions reached concerning the ecological significance of the risks.

(d) The Stage II Environmental Risk Characterization may also include the development of an environmental risk-based guideline for oil and/or hazardous material for which no environmental standards exists, and to the extent sufficient information concerning the environmental risks posed by the oil and/or hazardous material is available. Such guidelines shall be developed in a manner consistent with scientifically acceptable practices, taking into account guidance published by the Department or the U.S. Environmental Protection Agency, and information from the scientific literature, laboratory studies or field studies.

(e) Conclusions. A level of no significant risk of harm to the environment exists, or has been achieved, if:

1. there is no physical evidence of a continuing release of oil and/or hazardous material at or from the disposal site to surface waters and wetlands which significantly affects Environmental Receptors; and

2. there is no evidence of biologically significant harm (at the subpopulation, community, or system-wide level) known or believed to be associated with current or foreseeable future exposure of wildlife, fish, shellfish or other aquatic biota to oil and/or hazardous material at or from the disposal site; and

3. concentrations of oil and/or hazardous material at or from the disposal site do not and are not likely to exceed any applicable or suitably analogous environmental standards which have been formally promulgated, including Massachusetts Surface Water Quality Standards promulgated at 314 CMR 4.00 at current and reasonably foreseeable Exposure Points; and

4. there is no indication of the potential for biologically significant harm (at the subpopulation, community, or system-wide level), either currently or for any foreseeable period of time, to Environmental Receptors considering their potential exposures to oil and/or hazardous material and the toxicity of the OHM.

(5) The risk of harm to the environment shall also be characterized by comparing the concentration of each oil or hazardous material to the Upper Concentration Limits in Soil and Ground Water, as described in 310 CMR 40.0996.

(6) The documentation of the Method 3 environmental Risk Characterization shall clearly state whether or not a condition of no significant risk of harm to environmental resources, biota and habitats exists or has been achieved at the disposal site.

40.0996: Method 3 Upper Concentration Limits

(1) Upper Concentration Limits in soil and ground water are concentrations of oil and/or hazardous material which, if exceeded under the conditions specified below, indicate the potential for significant risk of harm to public welfare and the environment under future conditions. If a condition of No Significant Risk has not been achieved for future conditions but all substantial hazards have been eliminated, then the site may be eligible for a Class C RAO described in 310 CMR 40.1050.

(2) All comparisons of soil and ground water concentrations to Upper Concentration Limits in Soil and Ground Water required under 310 CMR 40.0000 shall be made using both:

(a) the arithmetic average of the concentration of oil or hazardous material at a disposal site; and

(b) the arithmetic average of the concentration of oil or hazardous material within any Hot Spot identified at the disposal site.

(3) The risk of harm to public welfare and the environment shall also be characterized by comparing the concentration(s) of oil or hazardous material in soil and ground water to the Upper Concentration Limits in Soil and Ground Water listed in 310 CMR 40.0996(7) or identified pursuant to 310 CMR 40.0996(8).

(a) A level of No Significant Risk of harm to public welfare and to the environment exists or has been achieved for both current and future conditions if the concentration of oil and/or hazardous material does not exceed an applicable Upper Concentration Limit, as described at 310 CMR 40.0996(2). If the Upper Concentration Limit in Soil or Ground Water for Total Petroleum Hydrocarbon is exceeded, a condition of No Significant Risk shall still be considered to exist if the concentrations of the Aliphatic and Aromatic Hydrocarbon Fractions comprising the TPH are less than or equal to the applicable Upper Concentration Limits in Soil and Ground Water.

(b) Except as provided in 310 CMR 40.0996(4), a level of No Significant Risk of harm to public welfare and to the environment does not yet exist for future conditions if the concentration of one or more oil and/or hazardous materials exceed an applicable Upper Concentration Limit, as described at 310 CMR 40.0996(2). The disposal site may, however, pose No Significant Risk for current conditions and meet the conditions of a Class C Response Action Outcome if all other requirements for a Class C Response Action Outcome are satisfied.

(4) For a disposal site at which the concentration of one or more oil and/or hazardous material in Soil exceeds an Upper Concentration Limit, a level of No Significant Risk of harm to public welfare and to the environment exists or has been achieved for both current and future conditions if a finding of No Significant Risk of harm to public welfare and the environment has been made pursuant to 310 CMR 40.0994 and 40.0995, respectively, an Activity and Use Limitation is implemented as required in 310 CMR 40. 1012(2), and the Soil with concentrations exceeding an Upper Concentration Limit:

(a) has been permanently immobilized or fixated as part of a remedial action;

(b) is located at a depth greater than 15 feet from the ground surface; or

(c) is located beneath an engineered barrier.

(5) An Engineered Barrier means a permanent cap with or without a liner that is designed, constructed and maintained in accordance with scientific and engineering standards to achieve a level of no significant risk for any foreseeable period of time.

(a) An Engineered Barrier shall:

1. prevent direct contact with contaminated media;

2. control any vapors or dust emanating from contaminated media;

3. prevent erosion and any infiltration of precipitation or run-off that could jeopardize the integrity of the barrier or result in the potential mobilization and migration of contaminants;

4. be comprised of materials that are resistant to degradation;

5. be consistent with the technical standards of RCRA Subpart N, 40 CFR 264.300, 310 CMR 30.600 or equivalent standards;

6. include a defining layer that visually identifies the beginning of the barrier; 7. be appropriately monitored and maintained to ensure the long-term integrity and performance in accordance with a monitoring and maintenance plan that shall be submitted to the Department and shall document that one or more financial assurance mechanism(s), detailed in 310 CMR 3 0.906, have been established and adequately provide for ongoing future monitoring, maintenance and any necessary replacement of the barrier;

(b) An Engineered Barrier shall not include an existing building, structure or cover material unless it is designed and constructed to serve as an engineered barrier pursuant to the requirements of 310 CMR 40.0996(4).

(6) The presence of non-aqueous phase liquids (NAPL) having a thickness equal to or greater than 1/2 inch in any environmental medium shall be considered a level which exceeds Upper Concentration Limits.

(7) Table 6 lists the Upper Concentration Limits in Ground Water and Soil.

(8) Except as specified in 310 CMR 40.0996(8)(c) for any oil or hazardous material not listed at 310 CMR 40.0996(7), either a default or chemical-specific Upper Concentration Limit must be used.

(a) The default Upper Concentration Limit in Ground Water shall be 10,000 μg/L and the default Upper Concentration Limit in Soil shall be 1,000 μg/g.

(b) The chemical-specific Upper Concentration Limits shall be calculated using the methodology presented at 310 CMR 40.0983 and 310 CMR 40.0984.

1. The Upper Concentration Limit in Ground Water shall be equal to ten times the highest ground water standard calculated at 310 CMR 40.0983 or 100,000 μg/L, whichever is lower.

2. The Upper Concentration Limit in Soil shall be equal to ten times the highest soil standard calculated at 310 CMR 40.0984, or 10,000 μg/g, whichever is lower.

(c) For the following oil and/or hazardous material, the Upper Concentration Limits in Soil and Ground Water are not applicable. As a result, the comparison of site concentrations to Upper Concentration Limits pursuant to 310 CMR 40.0996(3) is not required, and the need for an Activity and Use Limitation shall not be determined by comparison to an Upper Concentration Limit in Soil, as described in 310 CMR 40.1012(2)(a)3. and 310 CMR 40.1012(3)(b).

1. aluminum
2. asbestos
3. calcium
4. iron
5. potassium (excluding elemental potassium)
6. sodium (excluding elemental sodium)

(9) Ongoing monitoring shall be performed as necessary to ensure that a condition of No Significant Risk is maintained at any disposal site where a Permanent Solution has been achieved and the concentration of one or more oil and/or hazardous material is greater than the Upper Concentration Limit. The results of such monitoring shall be submitted to the Department.