18 AAC 75.340 - Soil cleanup levels; general requirements
(a) This section
provides the requirements for cleanup levels for hazardous substances in soil.
For each site, except as provided in (b) of this section, a responsible person
shall propose soil cleanup levels for approval, shall base those cleanup levels
upon an estimate of the reasonable maximum exposure expected to occur under
current and future site conditions, and shall develop those cleanup levels
using one or more of the following methods:
(1) method one for petroleum
hydrocarbon-contaminated soil in
(A) a
non-Arctic zone as set out in Table A1 of
18 AAC 75.341(a);
or
(B) an Arctic zone as set out in
Table A2 of
18 AAC
75.341(b);
(2) method two for soil contaminated with
(A) chemicals other than petroleum
hydrocarbons as set out in Table B1 of
18 AAC 75.341(c);
or
(B) petroleum hydrocarbons as
set out in Table B2 of
18 AAC
75.341(d);
(3) method three, as described in (e) of this
section, for developing site-specific alternative cleanup levels;
(4) method four, as described in (f) of this
section, for developing site-specific alternative cleanup levels.
(b) Alternative soil cleanup
levels developed under method three or method four may not be used at another
site without prior approval. If alternative cleanup levels are developed for
one site within a facility with multiple similarly contaminated sites, and if
the department determines that the use of those cleanup levels at another site
within that facility will be protective of human health, safety, and welfare,
and of the environment, the department will approve the use of those cleanup
levels at the other site.
(c) For
methods two, three, and four, a responsible person shall demonstrate that the
Arctic zone soil cleanup level, if applicable, is protective of migration to
surface water.
(d) The soil cleanup
levels provided under method one and method two apply at a contaminated site
unless the department develops an alternative cleanup level or approves an
alternative cleanup level that the responsible person has proposed under method
three or method four. To obtain approval for an alternative cleanup level, a
responsible person must demonstrate that an alternative cleanup level proposed
under method three or method four is protective of human health, safety, and
welfare, and of the environment, and must demonstrate compliance with the
applicable institutional control requirements under
18 AAC 75.375. The cleanup level
that applies at a site is the most stringent of either the alternative cleanup
level or, for a pathway where no alternative cleanup level was calculated, the
listed value for a hazardous substance in Table B1 of
18 AAC 75.341(c)
or Table B2 of
18 AAC
75.341(d).
(e) Under method three, a responsible person
may propose for the department's approval or the department may set an
alternative cleanup level for a hazardous substance listed in Table B1 of
18 AAC 75.341(c)
or Table B2 of
18 AAC 75.341(d)
that modifies the level for the
(1) migration
to groundwater or human health pathway in Table B1 or migration to groundwater
or inhalation pathway in Table B2, based on the use of approved site-specific
soil data, and the equations set out in the department's Procedures for
Calculatin Cleanup Levels, dated September 15, 2016, and adopted by
reference;
(2) migration to
groundwater pathway in Table B1 or Table B2 based on approved site-specific
soil and groundwater data and an approved fate and transport model that
demonstrates that alternative soil cleanup levels are protective of the
applicable groundwater cleanup levels under
18 AAC 75.345; or
(3) human health pathway in Table B1 or
ingestion or inhalation pathway in Table B2 based on use of commercial or
industrial exposure parameters listed in Appendix B of the Procedures
for Calculating Cleanup Levels, adopted by reference in (1) of this
subsection, if the department determines that the site serves a commercial or
industrial land use; the department will base a land use determination under
this paragraph upon
(A) consultation with the
public, including the local zoning authority, in any;
(B) a determination that the site does not
serve a residential land use;
(C) a
determination that the site will not serve a future residential land use based
on consideration of the factors in EPA's Land Use in the CERCLA Remedy
Selection Process, OSWER Dir. No. 9355.7-04, dated May 25, 1995,
adopted by reference; land in an undeveloped area for which it would be
difficult to determine a future use pattern is capable of being a residential
area, unless demonstrated otherwise; and
(D) consent of each landowner who is affected
by the contamination at the site that a cleanup level less stringent than a
cleanup level appropriate to residential land use is appropriate for the
site.
(f)
Under method four, the department will approve a site-specific alternative
cleanup level if a responsible person
(1)
performs a site-specific risk assessment and submits a risk assessment report
to the department for approval, and if the department determines that the
alternative cleanup level is protective of human health, safety, and welfare,
and of the environment, based on the site-specific risk assessment; in
performing the risk assessment, a responsible person shall follow the
department's Risk Assessment Procedures Manual,dated October
1, 2015, adopted by reference; and
(2) obtains the consent of each landowner who
is affected by the contamination at the site that a cleanup level less
stringent than a cleanup level appropriate to residential land use is
appropriate for the site.
(g) The department will develop a
site-specific cleanup level for a hazardous substance not listed under
18 AAC 75.341(c)
using the procedures set out in the department's Risk Assessment
Procedures Manual, adopted by reference in (f)(1) of this section,
unless the responsible person demonstrates that a site-specific cleanup level
is not necessary to ensure protection of human health, safety, and welfare, and
of the environment.
(h) The
department will approve less stringent soil cleanup levels, subject to any
institutional controls required under
18 AAC 75.375, if a responsible
person demonstrates that
(1) background
concentrations of a hazardous substance in the site area exceed the applicable
cleanup level set out in
18 AAC 75.341 for the hazardous
substance; or
(2) the practical
quantitation limit for the hazardous substance exceeds the applicable cleanup
level set out in
18 AAC 75.341 for that
substance.
(i) The
department will require a responsible person to modify a cleanup level under
this section or to perform a site-specific analysis of additional site risks if
the department determines that
(1) as a
result of site conditions or new data, a modification is necessary to protect
human health, safety, or welfare, or the environment; or
(2) a site-specific analysis is necessary due
to
(A) exposure pathways such as the potential
for the accumulation of vapors in buildings or other structures at levels that
threaten human health;
(B) sediment
contamination;
(C) impacts to
ecological receptors;
(D) other
site uses such as recreational, agricultural, or subsistence use; or
(E) the presence of sensitive subpopulations
who respond biologically to lower levels of exposure to a hazardous
substance.
(j)
Soil cleanup levels based on
(1) migration of
a hazardous substance to groundwater must be attained in the surface soil and
the subsurface soil;
(2) human
exposure from ingestion of or dermal contact with soil, or from inhalation of
particulates or a volatile hazardous substance, must be attained in the surface
soil and the subsurface soil to a depth of 15 feet, unless an institutional
control or site conditions prevent human exposure to the subsurface soil;
and
(3) the maximum allowable
concentrations for petroleum hydrocarbons described in Table B2 of
18 AAC 75.341(d)
must be attained in the surface soil and the subsurface soil.
(k) For a cleanup conducted under
methods two and three, a chemical that is detected at one-tenth or more of the
Table B1 direct contact and inhalation cleanup levels set out in
18 AAC 75.341(c)
must be included when calculating cumulative risk under
18 AAC
75.325(g).
Notes
The documents adopted by reference in 18 AAC 75.340 may be reviewed at, or requested from, the department's offices in Anchorage, Fairbanks, Juneau, and Soldotna. The documents adopted by reference may also be viewed through the department's Internet website at http://dec.alaska.gov/spar/csp/guidance_forms/csguidance.htm.
Authority: AS 46.03.020
AS 46.03.050
AS 46.03.710
AS 46.03.740
AS 46.03.745
AS 46.04.020
AS 46.04.070
AS 46.09.020
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