25 Pa. Code § 250.305 - MSCs for soil
(a) A person
shall implement a remedy under the Statewide health standard that is protective
of human health and the environment.
(b) The MSCs for regulated substances in soil
are presented in Appendix A, Tables 3 and 4. The methodology for calculating
MSCs in soil is detailed in subsections (c)-(e) and the MSCs are further
limited to not exceed the physical capacity of the soil to contain a regulated
substance. This physical limitation is based on an assumed porosity of 0.35, an
assumed dry bulk density of soil of 1.8 kilograms per liter and an assumed
density of a regulated substance of 1.0 kilograms per liter. This is calculated
according to the equation in paragraph (1). For regulated substances which are
organics and liquids at standard temperature and pressure (STP) as identified
in Appendix A, Table 5 (Chemical Properties), the physical limitation is
further limited based on residual saturation with the additional assumption of
a residual saturation ratio of substance volume to soil volume of 0.051, as
calculated in Equation (2).
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(c) For the residential standard,
the MSC for regulated substances contained in soil is one of the following:
(1) The lowest of the following:
(i) The ingestion numeric value throughout
the soil column to a depth of up to 15 feet from the existing ground surface as
determined by the methodology in §
250.306 (relating to ingestion
numeric values), using the appropriate default residential exposure assumptions
contained in § 250.306(d).
(ii) The inhalation numeric value throughout
the soil column to a depth of up to 15 feet in soil from the existing ground
surface, which considers volatilization into the outdoor air and inhalation of
particulates, as determined by the methodology in §
250.307 (relating to inhalation
numeric values), using the appropriate default residential exposure assumptions
contained in §
250.307(d).
(iii) The soil-to-groundwater pathway numeric
value throughout the entire soil column as determined by the methodology in
§ 250.308 (relating to soil to groundwater pathway numeric
values).
(2) The lowest
of paragraph (1)(i) and (ii) and, in addition, one of the following:
(i) A demonstration of the
soil-to-groundwater pathway soil buffer as identified in §
250.308(b), if
applicable.
(ii) A
soil-to-groundwater pathway equivalency demonstration as identified in §
250.308(d).
(d)
For the nonresidential standard, the MSC for regulated substances contained in
soil throughout the soil column to a depth of 2 feet from the existing ground
surface is one of the following:
(1) The
lowest of the following:
(i) The ingestion
numeric value as determined by the methodology in § 250.306, using the
appropriate default nonresidential exposure assumptions contained in §
250.306(e).
(ii) The inhalation
numeric value which is the lower of the values for volatilization into the
outdoor air and the inhalation of particulates, as determined by the
methodology in § 250.307, using the appropriate default nonresidential
exposure assumptions contained in §
250.307(d).
(iii) The soil-to-groundwater pathway numeric
value throughout the entire soil column as determined by the methodology in
§
250.308.
(2) The lowest of paragraph (1)(i) or (ii)
and, in addition, one of the following:
(i) A
demonstration of the soil-to-groundwater pathway soil buffer as identified in
§
250.308(b), if
applicable.
(ii) A
soil-to-groundwater pathway equivalency demonstration as identified in §
250.308(d).
(e)
For the nonresidential standard, the MSC for regulated substances contained in
soils at depths greater than 2 feet through 15 feet from the existing ground
surface, is one of the following:
(1) The
lowest of the following:
(i) The inhalation
numeric value which considers volatilization to the outdoor air, as determined
by the methodology in § 250.307, using the appropriate default
nonresidential exposure assumptions contained in §
250.307(d), and
using a transfer factor (TF) based upon the calculated emission rate from
subsurface soil as specified in the method of Jury, et al. 1990. Water
Resources Research, Vol. 26, No. 1, pp. 13-20.
(ii) The soil-to-groundwater pathway numeric
value throughout the entire soil column as determined by the methodology in
§
250.308.
(2) The value identified in paragraph (1)(i)
and one of the following:
(i) A demonstration
of the soil-to-groundwater pathway soil buffer as identified in §
250.308(b), if
applicable.
(ii) A
soil-to-groundwater pathway equivalency demonstration as identified in §
250.308(d).
(f) The MSC for regulated substances
contained in soil at depths greater than 15 feet is one of the following:
(i) The soil-to-groundwater pathway numeric
value as determined by § 250.308(a).
(ii) A demonstration of the
soil-to-groundwater pathway soil buffer as identified in §
250.308(b), if
applicable.
(iii) A
soil-to-groundwater pathway equivalency demonstration as identified in §
250.308(d).
(g) A person
conducting a remediation of soils contaminated with one or more substances
having a secondary MCL, but no toxicological properties listed in Appendix A,
Table 5B, will not be required to comply with either the direct contact pathway
or the soil-to-groundwater pathway requirements for those substances. The
substances shall be subject to the requirements of §
250.311(a) through (f)
(relating to evaluation of ecological
receptors) with respect to evaluation of ecological receptors.
Notes
The provisions of this § 250.305 amended under sections 104(a) and 303(a) of the Land Recycling and Environmental Remediation Standards Act (35 P.S. §§ 6026.104(a) and 6026.303(a)); and section 1920-A of The Administrative Code of 1929 (71 P.S. § 510-20).
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