Administrative Rules of Montana
Department 17 - ENVIRONMENTAL QUALITY
Chapter 17.50 - SOLID WASTE MANAGEMENT
Subchapter 17.50.13 - Ground Water Monitoring and Corrective Action
Rule 17.50.1311 - HYDROGEOLOGIC AND SOILS CHARACTERIZATION
Universal Citation: MT Admin Rules 17.50.1311
Current through Register Vol. 6, March 22, 2024
(1) The owner or operator of a facility required to monitor ground water shall prepare a site-specific hydrogeologic and soils report, pursuant to (2), for the facility. The following criteria and exceptions also apply:
(a) The owner or
operator of a Class IV landfill unit located within the ground water monitoring
network of a licensed Class II landfill is not required to submit a
hydrogeologic and soils report;
(b)
The owner or operator of an existing facility or lateral expansion required to
monitor ground water under this rule shall submit to the department for
approval a hydrogeologic and soils work plan that describes the proposed
sampling, analysis, and collection methods for the data required in (2), within
the following time frames:
(i) draft work
plan(s) must be submitted within 90 days after the department mails a
notification to applicant that a hydrogeologic and soils report is
required;
(ii) revised work plan(s)
must be submitted within 30 days after the department comments are mailed to
the applicant; and
(iii) final
hydrogeologic and soils reports must be submitted within 180 days after the
department's approval of the work plan is mailed by the department to the
applicant.
(2) A hydrogeologic and soils report required in (1) must include the following:
(a)
descriptions of the regional and facility specific geologic and hydrogeologic
characteristics affecting ground water flow beneath the facility, including:
(i) regional and facility specific
stratigraphy;
(ii) structural
geology;
(iii) ground water
potentiometric maps;
(iv) a
discussion of any regional deep aquifers;
(v) regional and facility specific ground
water flow patterns;
(vi)
characterization of seasonal variations in the ground water flow regime;
and
(vii) identification and
description of the confining layers present, both above and below the saturated
zone(s);
(b) an analysis
of any topographic features that influence the ground water flow;
(c) a description of the hydrogeologic units
that overlie the uppermost aquifer, or underground drinking water source, as
required in ARM
17.50.1204, or that may be part of
the leachate migration pathways at the facility, including saturated and
unsaturated units;
(d) a
description of hydrogeologically significant sand and gravel layers in
unconsolidated deposits;
(e) a
description of manmade structures that affect the hydrogeology of the site,
such as:
(i) local water supply
wells;
(ii) pipelines;
(iii) drains;
(iv) ditches; and
(v) septic tanks;
(f) for each ground water monitoring well at
the facility, the following information:
(i)
location;
(ii) elevation;
(iii) well log;
(iv) sampling history; and
(v) operational history; and
(g) any other information
determined by the department to be necessary to adequately characterize the
hydrogeologic characteristics of the solid waste landfill facility.
(3) If soil borings are necessary to obtain the information required in (2), the soil borings must be conducted as follows:
(a) all borings must be within
300 feet of the limits of waste filling, if practical;
(b) borings must extend a minimum of 20 feet
below the base of waste disposal areas, or to bedrock, whichever is
less;
(c) the minimum required
number of borings is as follows:
(i) 0-10
acres............................................................................................................................15
borings;
(ii) 11-20
acres.....................................................................................add
one boring per additional acre;
(iii) 20-40
acres.....................................................................add
one boring per additional two acres; and
(iv) 41 or more
acres....................................................................add
one boring per additional four acres;
(d) 75% of the required number of borings may
be conducted with a backhoe to a depth of ten feet; and
(e) borings not converted to wells must be
abandoned pursuant to ARM
17.50.1312.
75-10-204, MCA; IMP, 75-10-204, 75-10-207, MCA;
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