Washington Administrative Code
Title 173 - Ecology, Department of (See also Titles 197, 317, 372, and 508)
Chapter 173-351 - Criteria for municipal solid waste landfills
Section 173-351-440 - Assessment monitoring program
Current through Register Vol. 24-06, March 15, 2024
(1) Assessment monitoring is required whenever a statistically significant increase over background has been detected for one or more of the constituents listed in the Appendix I or in the alternative list approved in accordance with WAC 173-351-450, Alternative groundwater monitoring programs.
(2) Background data development for total metals must be done in accordance with WAC 173-351-430(2)(b) for existing MSWLF units under assessment monitoring as of November 1, 2012.
(3) Within ninety days of triggering an assessment monitoring program, and annually thereafter, the owner or operator must sample and analyze the groundwater for all constituents identified in Appendix III. A minimum of one sample from each well (background and downgradient) must be collected and analyzed during each sampling event. For any constituent detected in wells as a result of the complete Appendix III analysis, a minimum of four independent samples must be collected from each well (background and downgradient) within a time period of one hundred eighty days, and analyzed to establish background for the constituents. Each independent sample must be collected no less than one month apart from the previous sampling event.
(4) After obtaining the results from initial or subsequent sampling events required in subsection (3) of this section, the owner or operator must:
(5) If the concentrations of all Appendix III constituents are shown to be at or below background values, using the statistical procedures in WAC 173-351-420, for two consecutive sampling events, the owner or operator may return to detection monitoring after:
(6) If the concentrations of any Appendix III constituents are above background values, but all concentrations are below the groundwater protection standard established under subsection (8) of this section, using the statistical procedures in WAC 173-351-420, the owner or operator must continue assessment monitoring in accordance with this section.
(7) If one or more Appendix III constituents are detected at statistically significant levels above the groundwater protection standard established under subsection (8) of this section in any sampling event, the owner or operator must, within fourteen days of this finding, notify the jurisdictional health department, the department and all appropriate local government officials of the increase and place a notice in the operating record identifying the Appendix III constituents that have exceeded the groundwater protection standard. The owner or operator also:
(8) The owner or operator:
Statutory Authority: RCW 70.95.020(3), 70.95.060(1), and 70.95.260(1), (6). 12-23-009 (Order 07-15), § 173-351-440, filed 11/8/12, effective 12/9/12. Statutory Authority: Chapter 70.95 RCW and 40 CFR 258. 93-22-016, § 173-351-440, filed 10/26/93, effective 11/26/93.