WAC 173-304-490   Groundwater monitoring requirements.  (1) Applicability. These requirements apply to owners and operators of landfills, piles, landspreading disposal facilities, and surface impoundments that are required to perform groundwater monitoring under WAC 173-304-400.

     (2) Groundwater monitoring requirements.

     (a) The groundwater monitoring system must consist of at least one background or upgradient well and three down gradient wells, installed at appropriate locations and depths to yield groundwater samples from the upper most aquifer and all hydraulically connected aquifers below the active portion of the facility.

     (i) Represent the quality of background water that has not been affected by leakage from the active area; and

     (ii) Represent the quality of groundwater passing the point of compliance. Additional wells may be required by the jurisdictional health department in complicated hydrogeological settings or to define the extent of contamination detected.

     (b) All monitoring wells must be cased in a manner that maintains the integrity of the monitoring well bore hole. This casing must allow collection of representative groundwater samples. Wells must be constructed in such a manner as to prevent contamination of the samples, the sampled strata, and between aquifers and water bearing strata and in accordance with chapter 173-160 WAC, Minimum standards for construction and maintenance of water wells.

     (c) The groundwater monitoring program must include at a minimum, procedures and techniques for:

     (i) Decontamination of drilling and sampling equipment;

     (ii) Sample collection;

     (iii) Sample preservation and shipment;

     (iv) Analytical procedures and quality assurance;

     (v) Chain of custody control; and

     (vi) Procedures to ensure employee health and safety during well installation and monitoring.

     (d) Sample constituents.

     (i) All facilities shall test for the following parameters:

     (A) Temperature;

     (B) Conductivity;

     (C) pH;

     (D) Chloride;

     (E) Nitrate, nitrite, and ammonia as nitrogen;

     (F) Sulfate;

     (G) Dissolved iron;

     (H) Dissolved zinc and manganese;

     (I) Chemical oxygen demand;

     (J) Total organic carbon; and

     (K) Total coliform.

     (ii) The jurisdictional health department in consultation with the department may specify additional or fewer constituents depending upon the nature of the waste; and

     (iii) Test methods used to detect the parameters of (d)(i) of this subsection shall be EPA Publication Number SW-846, Test Methods for Evaluating Solid Waste - Physical/Chemical Methods except for total coliform which shall use the latest edition of Standard Methods for the Examination of Water and Wastewater.

     (e) The groundwater monitoring program must include a determination of the groundwater surface elevation each time groundwater is sampled.

     (f) The owner or operator shall use a statistical procedure for determining whether a significant change over background has occurred. The jurisdictional health department will approve such a procedure with the guidance of the department.

     (g) The owner or operator must determine groundwater quality at each monitoring well at the compliance point at least quarterly during the life of an active area (including the closure period) and the post-closure care period. The owner or operator must express the groundwater quality at each monitoring well in a form necessary for the determination of statistically significant increases.

     (h) The owner or operator must determine and report the groundwater flow rate and direction in the uppermost aquifer at least annually.

     (i) If the owner or operator determines that there is a statistically significant increase for parameters or constituents at any monitoring well at the compliance point, the owner or operator must:

     (i) Notify the jurisdictional health department of this finding in writing within seven days of receipt of the sampling data. The notification must indicate what parameters or constituents have shown statistically significant increases;

     (ii) Immediately resample the groundwater in all monitoring wells and determine the concentration of all constituents listed in the definition of contamination in WAC 173-304-100 including additional constituents identified in the permit and whether there is a statistically significant increase such that the groundwater performance standard has been exceeded, and notify the jurisdictional health department within fourteen days of receipt of the sampling data.

     (j) The jurisdictional health department may require corrective action programs including facility closure if the performance standard of WAC 173-304-460 (2)(a) is exceeded and, in addition, may revoke any permit and require reapplication under WAC 173-304-600.

     (3) Corrective action program. An owner or operator required to establish a corrective action program under this section must, at a minimum with the approval of the jurisdictional health officer:

     (a) Implement a corrective action program that reduces contamination and if possible prevents constituents from exceeding their respective concentration limits at the compliance point by removing the constituents, treating them in place, or other remedial measures;

     (b) Begin corrective action according to a written schedule after the groundwater performance standard is exceeded;

     (c) Terminate corrective action measures once the concentrations of constituents are reduced to levels below the limits under WAC 173-304-460 (2)(a).



[Statutory Authority: Chapter 43.21A RCW. 85-22-013 (Order 85-18), § 173-304-490, filed 10/28/85.]