ARCHIVED REPORTS_2010_2011 ANNUAL MONITORING REPORT

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CRA MEMORANDUM Page 3 MATRIX SPIKE/MATRIX SPIKE DUPLICATE (MS/MSD) ANALYSES To assess the long term accuracy and precision of the analytical methods on various matrices, MS/MSD percent recoveries and relative percent differences (RPD) of the concentrations were determined. The organic MS/MSD percent recovery and RPD control limits are established by the laboratory. The inorganic control limits are defined by the methods and the "Guidelines",which require recoveries between 75 to 125 percent with RPDs less than 20 percent for water samples and 30 percent for soil samples. Matrix spikes (MS) were prepared and analyzed in duplicate for total and dissolved iron and manganese, anions, ammonia,sulfide and COD. All recoveries were within required control limits showing adequate analytical accuracy and precision. Precision,for DRO,alkalinity,BOD and permanent dissolved gases,was determined to be acceptable based on LCS/LCSD recoveries. Precision,for TOC and DOC,was determined to be acceptable based on laboratory duplicate recoveries. FIELD QUALITY ASSURANCE/QUALITY CONTROL (QA/QCI The field QA/QC consisted of field duplicate sample sets and equipment blanks. Overall precision for the sampling event and laboratory procedures was monitored using the results of the field duplicate sample sets. The RPDs associated with these duplicate samples must be less than 50 percent for water or 100 percent for soil/sediment. If the reported concentration in either the investigative sample or its duplicate is less than five times the RL,the evaluation criteria are;one times the RL value for water or two times for soil/sediment. All field duplicate results were acceptable indicating good field and analytical precision. To monitor potential cross-contamination during sample collection, equipment blanks were submitted to the laboratory for analysis. All equipment blank results were non-detect for the compounds of interest with one exception. Several sample results were qualified as non-detect (See Table 2). OVERALL ASSESSMENT The data were found to exhibit acceptable levels of accuracy and precision,based on the provided information, and may be used with the qualifications noted.