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Ryegrass Limited Purpose Landfill and Balefill Closed Landfill <br />Groundwater and Leachate Sampling and Analysis Plan <br />Kittitas County Solid Waste <br />2.6.3.2 Accuracy <br />Accuracy is assessed using the results of standard reference material, linear check samples, and MS <br />analyses. It is normally expressed as a percent recovery, which is calculated; <br />Percent = (Total Analvte Found - Analvte Originallv Present) x 100 <br />Recovery Analyte Added <br />The percent recovery will be routinely calculated and evaluated in accordance with EPA guidance <br />(EPA 2O20a,b). <br />2.63.3 Bias <br />Bias is the systematic or persistent distortion of a measurement process that causes errors in one <br />direction. Bias will be assessed with field duplicate and laboratory matrix spike samples, similar to <br />that described for accuracy. Bias measurements are usually carried out with a minimum frequency <br />of 1 in 20, or one per batch of samples analyzed, under the same sampling episode. <br />2.6.3.4 Sensitivity <br />Sensitivity expresses the capability of a method or instrument for meeting prescribed measurement <br />reporting limits. Sensitivity will be assessed by comparing data reporting limits with applicable <br />cleanup criteria and analytical or instrument method reporting limits. <br />2.&&5 Completeness <br />The amount of valid data produced will be compared with the total analyses performed to assess the <br />percent of completeness. Completeness will be routinely calculated and evaluated in accordance <br />with EPA guidance (EPA 2O20a,b). <br />2.63.6 Comparability <br />Comparability is a qualitative parameter expressing the confidence with which one data set can be <br />compared with another. Sample data will be comparable with other measurement data for similar <br />samples and sample conditions. Comparability of the data will be maintained by using consistent <br />methods and units. <br />Sample locations and sampling procedures will have been chosen to maximize representativeness. A <br />qualitative assessment (based on professional experience and judgment) will be made of sample <br />data representativeness based on review of sampling records and QA audit of field activities. <br />2.7 Equipment Decontamination <br />To mitigate the potential for cross -contamination, all nondedicated, sample -contacting, and <br />downhole equipment used in the collection and sampling processes will be decontaminated before <br />sample collection. Included are nondedicated pumps, groundwater level measurement devices, and <br />nondedicated filtering apparatuses. <br />A water level probe must be dedicated to groundwater monitoring well use only. Under no <br />circumstance shall this dedicated probe be used to measure other fluid levels (e.g., leachate). <br />April 2024 1 553-1763-010 2-11 <br />Revised May 2024 <br />