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Consent Decree Exhibit C drain. The drain has been sealed and currently no landfill gas is detectable within the restroom. 3.2 GROUNDWATER EXPOSURE PATHWAY 3.2.1 G rou ndwater ARARs Potential ARARs for the Everett Landfill/Tire Fire Site are described in an attachment CAP-1. ARARs specific to the groundwater exposure pathway are summarized below. • Water Quality Standards for the Surface Waters of the State of Washington, Section 90.48 RCW; Section 173-201 A WAC • Federally Promulgated Water Standards, 40 CFR 131 and 141 • Group A Public Water Systems, Chapter 246-290-310 WAC 3.2.2 Groundwater Cleanup Standards Cleanup standards [WAC 173-340-700] consist of selected appropriate levels of cleanup applied at a defined point of compliance. Appropriate levels of cleanup for groundwater are determined by the highest beneficial use of that groundwater. For the Everett Landfill/Tire Fire Site, cleanup standards are slightly different for the shallow (leachate) aquifer and the deep aquifer. 3.2.2.1 Shallow (Leachate) Aquifer The shallow (leachate) aquifer is not a current or potential drinking water source. Water in this aquifer is collected and conveyed off -site for treatment by fie leachate collection system. Shallow aquifer cleanup standards are therefore based on the protection of water quality in the deep aquifer and in the adjacent surface water bodies. The shallow aquifer point of compliance is located on the strip of land between the leachate collection trench and the East Ditch. Compliance criteria for the shallow aquifer will be based on hydraulic control through operation of the leachate collection system. Demonstration of hydraulic control would occur by monitoring water levels to show that hydraulic gradients are toward the leachate collection system, indicating no shallow aquifer discharge to surface water. If, at some point in the future, shallow (leachate) groundwater quality meets cleanup levels, hydraulic control through operation of the leachate collection system would no longer be necessary. 3.2.2.2 Deep Aquifer The deep aquifer located under the Landfill/Tire Fire Site is a potential future source of drinking water under MTCA although currently cannot be used directly for drinking water purposes per well installation regulations. The deep aquifer does, however, discharge to the Snohomish River, which is classified as a potential drinking water source. Therefore, deep aquifer cleanup levels are based on: 1. The most stringent of the following standards: MTCA A or MTCA B for groundwater (drinking water standards), drinking water maximum contaminant levels (MCLs), or surface water standards based on consumption of organisms, OR FINAL - March 2001 3-3 Everett Landfill Tire Fire Site Cleanup Action Plan