WAC 173-351-140   Other location restrictions.  (1) Groundwater.

     (a) Liner separation. No new MSWLF unit or lateral expansion shall be located at a site where the bottom of the lowest liner is any less than ten feet (three meters) above the seasonal high level of groundwater in any water bearing unit which is horizontally and vertically extensive, hydraulically recharged and volumetrically significant as to harm or endanger the integrity of the liner at any time, unless a demonstration during the permit process of WAC 173-351-700 can be made that a hydraulic gradient control system or the equivalent can be installed to control groundwater fluctuations and maintain a five foot (1.5 meter) separation between the controlled seasonal high level of groundwater in the identified water-bearing unit and the bottom of the lowest liner. The owner or operator must place the demonstration in the application for a permit under WAC 173-351-700 and be issued a solid waste permit by the jurisdictional health department.

This demonstration must include:

     (i) A hydrogeologic report required in WAC 173-351-490 including a discussion showing the effects from subsoil settlement, changes in surrounding land uses affecting groundwater levels, liner leakage or other impacts will not bring any hydrostratigraphic unit to within five feet (1.5 meters) of the bottom of the lowest liner during the active life, closure and post-closure of the MSWLF unit;

     (ii) Any currently available ground/surface water quality data for aquifers, springs, or streams in direct hydrologic contact with landfill's active area;

     (iii) A showing that any gradient-control discharges to groundwater will not adversely impact existing groundwater/surface water users or the instream flow of surface waters in direct hydrologic contact or continuity with the landfill's hydraulic gradient control system;

     (iv) Conceptual engineering drawings of the proposed MSWLF unit and discussion as to how the hydraulic gradient control system will not affect the structural integrity nor performance of the liner;

     (v) Design specifications for the proposed ground and surface water monitoring systems; and

     (vi) Preliminary engineering drawings of the hydraulic gradient control system (if applicable).

     (b) Sole source aquifers. No new MSWLF unit or lateral expansion shall be located over a designated sole source aquifer unless the owner or operator can demonstrate during the permit process of WAC 173-351-700 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 and be issued a solid waste permit by the jurisdictional health department. 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 hydrogeologist or other professional groundwater scientist in accordance with WAC 173-351-400(2); 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).

     (c) Drinking water supply wells. No new MSWLF unit or lateral expansion active area shall 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 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 and be issued a solid waste permit by the jurisdictional health department. Such a demonstration must 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 shall 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 currently 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;

     (iv) Design specifications for the proposed ground and surface water monitoring systems; and

     (v) A statement that the demonstration has been prepared by a hydrogeologist or qualified groundwater scientist in accordance with 173-351-400(2).

     (2) Surface water. No new MSWLF unit or lateral expansion active area shall be located within two hundred feet (sixty-one meters) measured horizontally from the ordinary high water mark, of a shoreline of the state as defined in RCW 90.58.030 (which includes some wetlands associated with waters of the state), nor any public land that is being used by a public water system for watershed control for municipal drinking water purposes in accordance with WAC 246-290-450.

     See also wetlands in WAC 173-351-130(4). Local wetlands protection ordinances should be consulted to determine if greater setbacks are required.

     (3) Land use. No new MSWLF unit or lateral expansion shall be located:

     (a) In areas designated by the United States Fish and Wildlife Service or the department of wildlife as critical habitat for endangered or threatened species of plants, fish, or wildlife;

     (b) So that the active area is any closer than one hundred feet (thirty meters) to the facility property line for land zoned as nonresidential or for unzoned lands, except that the active area shall be no closer than two hundred fifty feet (seventy-six meters) to the property line of adjacent land zoned as residential, existing at the time of the purchase of the property containing the active area.

     (c) So as to be at variance with any locally-adopted land use plan or zoning requirement unless otherwise provided by local law or ordinance; and

     (d) So that the active area is any closer than one thousand feet (three hundred meters) to any state or national park.

     (4) Toxic air emissions. See WAC 173-351-200 (5)(a).

     (5) Cover material. See WAC 173-351-200 (2)(a).

     (6) Capacity. See WAC 173-351-010 (2)(c).

     (7) Climatic factors. See WAC 173-351-300 (2)(b) for climatic factors.

     (8) Natural soils. See WAC 173-351-300(2) for soil liner standards.



[Statutory Authority: Chapter 70.95 RCW and 40 CFR 258. 93-22-016, § 173-351-140, filed 10/26/93, effective 11/26/93.]