310 CMR, § 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 a Hazard Quotient (HQ) of 0.2 for each soil category shall be identified using the equations:

[OHM]_S1 = (HQ x RfD_chronic x C)/((RAF_oral x ADSE_S1oral) + (RAF_dermal x ADSE_S1dermal))

[OHM]_S2 = (HQ x RfD_chronic x C)/((RAF_oral x ADSE_S2oral) + (RAF_dermal x ADSE_S2dermal))

[OHM]_S3 = (HQ x RfD_subchronic x C)/((RAF_oral x ADSE_S3oral) + (RAF_dermal x ADSE_S3dermal))

Where:

[OHM] = The concentration of oil and/or hazardous material being derived, in units of milligrams per kilogram soil (mg/kg or ppm).

HQ = Hazard Quotient (HQ) of 0.2 (dimensionless).

RfD = The Reference Dose for the chemical, in units of milligrams contaminant per kilogram-day (mg/(kg x day)).

RAF_oral = The Relative Absorption Factor applicable for oral soil exposures (dimensionless).

RAF_dermal = The Relative Absorption Factor applicable for dermal soil exposures (dimensionless).

C =10⁶ mg/kg conversion factor.

ADSE = Average daily exposure to soil by the oral or dermal pathway in units of milligrams soil per kilogram-day (mg/(kg x day)).

ADSE values are:

S1 oral = 2.4 mg/(kg x day)

S1 dermal = 21 mg/(kg x day)

S2 oral = 0.27 mg/(kg x day)

S2 dermal = 0.49 mg/(kg x day)

S3 oral = 1.2 mg/(kg x day)

S3 dermal = 13 mg/(kg x day).

(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 for each soil category using the following equations:

[OHM] = (ELCR x C)/(CSF x ((RAF_oral x LADSE_oral) + (RAF_dermal x LADSE_dermal)))

Where:

[OHM] = The concentration of oil and/or hazardous material being derived, in units of milligrams OHM per kilogram soil (mg/kg or ppm).

ELCR = Method 1 Excess Lifetime Cancer Risk limit of one-in-one million (10^-6).

CSF = The oral Carcinogenic Slope Factor in units of risk per milligram per kilogram-day (mg/(kg x day))^-1.

RAF_oral = The Relative Absorption Factor applicable for oral soil exposures (dimensionless).

RAF_dermal = The Relative Absorption Factor applicable for dermal soil exposures (dimensionless).

C =10⁶ mg/kg conversion factor.

LADSE = Lifetime average daily exposure to soil by the oral or dermal pathway in units of milligrams soil per kilogram-day (mg/(kg x day)). LADSE values are:

S1 oral = 0.37 mg/(kg x day)

S1 dermal = 3.9 mg/(kg x day)

S2 oral = 0.10 mg/(kg x day)

S2 dermal = 0.19 mg/(kg x day)

S3 oral = 0.0088 mg/(kg x day)

S3 dermal = 0.095 mg/(kg x day).

(4) Considering the category determined for the groundwater 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 groundwater concentrations of the oil and/or hazardous material greater than the applicable MCP Method 2 groundwater standard derived in 310 CMR 40.0983 shall be identified.

(5) For each combination of soil and groundwater 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 groundwater 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 groundwater categories.

(9) MCP Method 2 soil standards identified in 310 CMR 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 ÷ ORL_50%

Where:

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

ORL_50% = 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).

Notes

310 CMR, § 40.0984

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