(1) In order to determine the full extent and location of
soils contaminated by the release and the presence and concentrations of free
and dissolved product contamination in the surface water and in ground water,
owners and operators must conduct a remedial investigation of the release, the
release site, and the surrounding area possibly affected by the release if any
of the following conditions exist:
(a) there is evidence that
ground water wells have been affected by the release (e.g., as found during
release confirmation or previous corrective action measures) ;
(b) free product is found
to need recovery in compliance with ARM 17.56.602(1) (c) ;
(c) there is evidence that
contaminated soils may be in contact with ground water (e.g., as found during
conduct of the initial response measures required under ARM 17.56.602) ; or
(d) the department or the
implementing agency requests a remedial investigation, based on the known or
potential effects of contaminated soil or ground water on nearby surface water,
ground water, and human health.
(2) After reviewing
information required under ARM 17.56.602 and 17.56.603, the department may
determine that no additional investigation or corrective action is necessary;
however, the department may require the owners and operators to initiate and
continue compliance monitoring as determined by the department.
(3) A remedial
investigation generally is an expanded site assessment more detailed in scope
than the initial response and abatement measures under ARM 17.56.602, which
must define the nature, extent, and magnitude of contamination and identify
threats to public health, welfare and to the environment. A remedial
investigation work plan must be submitted to the department prior to
implementation by the owners and operators. The department shall submit a copy
of a work plan from any owner or operator who is or may be seeking
reimbursement to the appropriate local government office with jurisdiction over
corrective action of the release. The office shall respond with any comments
within 15 days of receipt of the plan and the department shall approve or
disapprove the plan within 15 days of receipt from the local government. The
following information is required to complete the remedial investigation:
(a) site map(s) showing all
sampling locations, including the site(s) of:
(i) borings;
(ii) monitoring wells;
(iii) recovery wells;
(iv) vapor survey points;
and
(v) sites where any other
samples were taken.
(b) soil and bedrock
technical information and map(s) , including:
(i) soil type,
thickness, and classification below the site of the release;
(ii) unconsolidated material and bedrock type, thickness, and formation name below
the site of the release;
(iii) boring
logs and monitoring well logs (description of well, well construction methods,
sediment odors, and blow count) ;
(iv) soil
characteristics (grain size, sorting, origin, texture, permeability,
classification) ;
(v) observed
contamination (visual, odors, and vapor survey results) ; and
(vi) laboratory
analytical results.
(c) ground
water technical information and map(s) , including:
(i) general
description and characteristics of aquifers and unsaturated zone below the site
of the release, including:
(A) hydraulic
characteristics;
(B) depth to
water table;
(C) surveyed
water elevations and contours (potentiometric surface) ;
(D) direction
of ground water flow;
(E) rate of
ground water flow;
(F) perched
conditions; and
(G) connections
to other aquifers.
(ii) location,
ownership, use and construction of all municipal, domestic, irrigation,
industrial and monitoring wells within ½ mile of the site;
(iii) sampling
description;
(iv) results of
laboratory analysis.
(d) surface
water technical information and map(s) , including:
(i) location
and use of all surface water within one mile of site;
(ii) ground
water/surface water discharge points;
(iii) sampling
description; and
(iv) results of
laboratory analysis.
(e) description
of and map(s) showing the extent of free product and vapors discovered, whether
as a result of current or past vapors/seepage, in basements and other
subsurface structures and utilities. The description must include a copy of
the vapor survey.
(f) technical
conclusions, which must be stated with reasonable professional certainty and
under the standard of care applicable, must include at least:
(i) source of
the release;
(ii) current
extent of and potential for the release (determined with field or laboratory
analytical detection equipment) in or through the following media:
(A) soil;
lateral and vertical extent of fuel-soaked soil;
(B) free product; aerial
extent;
(C) water; dissolved phase
(water soluble constituents) ;
(D) vapor;
(g) sampling summary
charts, which clearly identify by the date on which the samples were taken, all
of the following: sample ID#, sampling location, sample type, date analyzed, laboratory
conducting the analysis, analytical method, and results of the analysis.
(h) laboratory report
sheets.
(4) If a remedial
investigation has been conducted, owners and operators must submit a report
containing the information collected under (3) within 120 days of release
confirmation. If investigation extends beyond the time for submission of the
report, owners and operators must also submit an additional follow-up
completion report according to a schedule established by the department.