(1) The owner or operator may propose changes
and/or alternate groundwater monitoring programs for detection monitoring after
the second year of groundwater monitoring under WAC
173-351-430(3),
or the assessment monitoring program of WAC
173-351-440 as follows:
(a) An alternate groundwater monitoring
frequency for sampling and analysis of Appendix I and II
constituents;
(b) A deletion of
Appendix I, II, and III constituents or alternate groundwater monitoring
constituents;
(c) An appropriate
subset of wells to be sampled and analyzed for Appendix III under WAC
173-351-440(2).
(2) All proposed changes in
groundwater monitoring frequency must be no less than semiannually for
detection monitoring and no less than quarterly for assessment monitoring. The
owner or operator must apply for a permit modification under WAC
173-351-720(6)
or must apply during the renewal process of WAC
173-351-720(5)
for changes in groundwater monitoring frequency making a demonstration based on
the following information:
(a) A
characterization of the hydrostratigraphic unit(s) including the unsaturated
zone, transmissive and confining units and include all of the following:
(i) Hydraulic conductivity; and
(ii) Groundwater flow rates.
(b) Minimum distance between
upgradient edge of the MSWLF unit and downgradient monitoring wells (minimum
distance of travel); and
(c)
Contaminant fate and transport characteristics.
(3) The owner or operator must apply for a
permit modification under WAC
173-351-720(6)
or must apply during the renewal process of WAC
173-351-720(5)
for all proposed deletions or changes to groundwater monitoring constituents of
Appendix I, II, and III based on all of the following information:
Verification that the removed constituents are not reasonably
expected to be in or derived from the waste contained in the unit, by:
(a) Leachate monitoring results consisting of
those parameters listed in Appendix I and II for deletions or changes to
detection monitoring and Appendix III for assessment monitoring. All leachate
monitoring must be quarterly unless otherwise approved by the jurisdictional
health department and the department;
(b) The types, quantities, and concentrations
of constituents in wastes managed at the MSWLF unit;
(c) The mobility, stability, and persistence
of waste constituents or their reaction products in the unsaturated zone
beneath the MSWLF unit;
(d) The
detectability of indicator parameters, waste constituents, and reaction
products in the groundwater; and
(e) The concentration or values and
coefficients of variation of monitoring parameters or constituents in the
groundwater background.
(4) Multiunit groundwater monitoring systems.
An owner or operator may propose during the permitting process
of WAC 173-351-700 or through the permit
modification process of WAC
173-351-720(6) a
multiunit groundwater monitoring system instead of separate groundwater
monitoring systems for each MSWLF unit, including MSWLF units which were closed
in accordance with chapter173-351, 173-304, or 173-301 WAC. The multiunit
system must meet all of the requirements of WAC
173-351-400 through WAC
173-351-490 and will be as
protective of human health and environment as individual groundwater monitoring
systems for each MSWLF unit. Permit approval for multiunit groundwater
monitoring systems and programs will be based on the ability to provide early
warning detection of any contaminant releases including:
(a) Number, spacing, and orientation of the
MSWLF units;
(b) Hydrogeologic
setting;
(c) Site
history;
(d) Engineering design of
the MSWLF units;
(e) Type of waste
accepted at the MSWLF units; and
(f) Leachate analysis as referenced in
subsection (3)(a) of this section for MSWLF units with leachate collection
systems.
