(1) Groundwater.
(a) Sole source aquifers. New MSWLF units and
lateral expansions may not be located over a designated sole source aquifer
unless the owner or operator can demonstrate during the permit process of WAC
173-351-700 or through the permit
modification process of WAC
173-351-720(6)
that the sole source aquifer is not vulnerable to potential groundwater
contamination from the active area. Vulnerability is defined as the propensity
or likelihood of a sole source aquifer to become contaminated should the
integrity of the engineering control (including liners) fail; it is a measure
of the propensity to deteriorate the water quality of a sole source aquifer,
and takes into account an assessment of the physical barriers, the physical
movement of contaminants, the hydraulic properties of the subsurface lithology;
the rate of a contaminant plume movement; the physical and chemical
characteristics of contaminants; and it also includes an assessment of the
likelihood and ease for contaminant removal or clean-up, or the arrest of
contamination, so as to not impact any further portion of the designated sole
source aquifer. The owner or operator must place the demonstration in the
application for a permit under WAC
173-351-700 or through the permit
modification process of WAC
173-351-720(6).
Such a vulnerability demonstration must include the submission of a
hydrogeologic report as required in WAC
173-351-490 and additionally must
meet the following performance criteria:
(i)
Demonstrates the presence of confining units or other lithology that will
prevent the migration of groundwater contamination;
(ii) Addresses the fate and transport of
contaminants, including interactions in the lithologic framework,
hydrogeochemical facies, contaminant travel times;
(iii) Defines and summarizes the groundwater
budgets for the active area and the sole source aquifer including recharge and
discharge areas and includes flow net diagrams;
(iv) Provides a contingency and groundwater
assessment plan for the immediate arrest of any groundwater contamination and
steps to assess the extent of contamination;
(v) Design specifications for the proposed
ground and surface water monitoring systems;
(vi) Is prepared by a geologist or other
licensed professional in accordance with the requirements of chapter 18.220
RCW, Geologists; and
(vii) "Sole
source aquifer" means an aquifer designated by the Environmental Protection
Agency pursuant to Section 1424e of the Safe Drinking Water Act ( PL 93-523
).
(b) Drinking water
supply wells. New MSWLF units and lateral expansions active area may not be
located closer than one thousand feet (three hundred meters) to any drinking
water supply well, in use and existing at the time of the purchase of the
property containing the active area unless the owner or operator can
demonstrate during the permit process of WAC
173-351-700 or through the permit
modification process of WAC
173-351-720(6)
that the active area is no less than a ninety-day hydraulic travel time to the
nearest down-gradient drinking water supply well in the first useable aquifer.
The owner or operator must place the demonstration in the application for a
permit under WAC
173-351-700 or through the permit
modification process of WAC
173-351-720(6).
Such a demonstration must be prepared by a geologist or other licensed
professional in accordance with the requirements of chapter 18.220 RCW,
Geologists, and include:
(i) A hydrogeologic
report required in WAC
173-351-490; and the necessary
calculations for showing compliance with the ninety-day travel time; the
ninety-day travel time must be based on the peak or full pumping capacity of
installed nearby wells and include potentiometric surface maps showing well
capture zones and radius of influence;
(ii) Any available ground/surface water
quality data for aquifers, springs, or streams in direct hydrologic contact
with landfill's active area;
(iii)
The waste management unit boundaries at facility closure; and
(iv) Design specifications for the proposed
ground and surface water monitoring systems.