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6. QUALITY CONTROL SAMPLES <br /> QC samples will be employed and monitored during implementation of the Work Plan. <br /> Laboratory QC samples are initiated and monitored by the laboratory as part of the <br /> testing procedures. Field QC samples will be collected in the field and used to evaluate <br /> the quality of the field sampling activities. Not all field and laboratory QC sample types <br /> apply to all proposed laboratory analytical methods. <br /> 6.1 Trip Blanks <br /> Trip blanks are used to detect VOC contamination during sample shipping and <br /> handling. Trip blanks will consist of 40-milliliter (mL) volatile organic analysis (VOA) <br /> vials of de-ionized water that are filled by the laboratory (Eurofins Calscience). Trip <br /> blanks will be transported to the sampling site, accompany the respective sampling <br /> containers during field activities, and be returned to Eurofins Calscience with the <br /> respective samples. Trip blanks will accompany the samples at the frequency of one per <br /> cooler containing VOC samples. <br /> 6.2 Field Duplicate Samples <br /> Field duplicate samples will be collected to assess the precision and overall quality of <br /> the sampling and analytical procedures. Field duplicate samples are collected at the <br /> same time and from the same source as the original sample. Field duplicate samples will <br /> be collected, numbered, packaged, and sealed in the same manner as other samples. The <br /> frequency for field duplicate sample collection and analysis is 1 per 20 primary <br /> samples, for groundwater, soil vapor, sub-slab vapor, and indoor air samples. The RPD <br /> between the results of the field duplicate and the original sample should be less than or <br /> equal to 30% for ground water samples and 50% for air samples. <br /> 6.3 Equipment Blanks <br /> Equipment blanks consist of laboratory-supplied deionized water that is placed into <br /> sampling containers at the same time and location of a field sample. The equipment <br /> blank sample is collected in the same manner as other samples, utilizing any non- <br /> dedicated, decontaminated sampling equipment (samplers, sample tubing, etc.). <br /> Equipment blanks are used to evaluate decontamination procedures of sampling <br /> equipment. Equipment blank samples apply only to non-dedicated field equipment and <br /> will be collected at a frequency of one per day, if non-dedicated sampling equipment is <br /> used. <br /> Appendix C 14 <br />