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GROUND ZERO ANALYSIS,INC. Quality Control/Quality Assurance Plan <br /> 10.0 GROUNDWATER SAMPLING PROTOCOLS <br /> 10.1 Well Sampling <br /> Prior to arriving at the sampling site, all sampling equipment will be washed with laboratory grade <br /> detergent, and rinsed twice with tap water, and once with deionized water. This procedure will be <br /> carried out on-site before sampling of other monitoring wells, if more than one well is to be sampled <br /> with the same sampling device. <br /> Immediately prior to sampling,the depth to water(DTW)in the well will be recorded. The thickness <br /> of free phase LNAPL on top of the groundwater,if present,will be measured using an interface probe. <br /> The procedure of monitoring is presented in Section 7.0 (Groundwater Monitoring Protocol). If free <br /> LNAPL is detected, analysis of groundwater at the interface for dissolve product will not be <br /> conducted. A product sample will be collected for source identification, as needed. If free product <br /> cannot be removed, an interval specific sampling device may be utilized to collect a sample from <br /> below the zone of free product. <br /> Before collecting groundwater sample from a well,the well will be purged until indicator parameters <br /> (temperature,conductivity and pH) stabilize. This will entail the removal of at least three well casing <br /> volumes. Temporary storage of purged water is outlined in Section 8.0, (Well Development <br /> Protocol). The indicator parameter measurements will be taken both before and after purging of each <br /> well casing volume. Once the well is purged and indicator parameters have stabilized, a sample will <br /> be collected after the water level approaches 80 percent of its initial elevation. Where water level <br /> recovery is slow, the sample will be collected after stabilization is achieved and enough water is <br /> present to fill sample container. <br /> Cross contamination from transferring pumps (or bailers) from well to well will be avoided by <br /> utilizing dedicated equipment. Where this is not feasible, thorough cleaning of equipment will be <br /> performed between sampling rounds. Sampling will proceed from the least contaminated to the most <br /> contaminated well, if information is available before sample collection, or if it is indicated by <br /> evidence. Where several types of analysis will be performed for a given well,individual samples will <br /> be collected in the following order: <br /> 1. Volatile organics <br /> 2. Purgeable organic hydrocarbons <br /> 3. Purgeable organic halogens <br /> 4. Total organic hydrocarbons <br /> 5. Total organic halogens <br /> 6. Extractable organics <br /> 7. Total metals <br /> 8. Dissolved metals <br /> 9. Phenols <br /> 10. Cyanide <br /> The specific analytical methods to be utilized for the common volatile/semi-volatile analyses are <br /> shown on Table 2. <br /> GAData\GROUNDZE\STALLWORTH AUTO SALES(N CA)1380\Workp1an\QA.QC Plan.docx <br /> 9 <br />