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06!03/99 16:41 FAX 510 313 0844 QST MARTINEZ [it 004/007 <br /> Mr.Jeff Wong <br /> lime 3, 1499 <br /> Page 3 <br /> The newly installed monitor well will be allowed to equilibrate for a minimum of 4 hours after <br /> installation and development before sampling occurs. Before a water sample is collected for <br /> chemical analysis, the water formerly stored in the well will be evacuated. The well will be <br /> evacuated to dryness or to remove a minimum of three volumes of standing water,whichever ooeurs <br /> fast <br /> The procedure for the well evacuation is a follows: <br /> 1. Well evacuation data will be recorded of the field sampling sheets as the data is obtained_ <br /> The field log will be kept by the sampling personnel and it will contain art a mininawaa: <br /> Date and time of sampling <br /> • Sample location <br /> • Sample number <br /> • Field measurements(if applicable) <br /> • Weather conditions <br /> • Special comments pertaining to the sampling event <br /> 2. For the well, the distance from the top of the casing to the water level in the well will be <br /> measured prior to disturbing the water column in the well. This depth will be recorded in <br /> feet on the data sheet along with the well number,the well location,the date and time,and <br /> the total well depth. <br /> 3. The volume(gallons) of the water contained in the well casing will be calculated using the <br /> appropriate conversions from well casing volumes. <br /> 4. A minimum of three times the volume in the well will be removed. In low yielding wells, <br /> %e well will be pumped dry. If the well is pumped dry,it will be allowed to recover for at <br /> least one hour and purged to dryness again. <br /> Well evacuation will be performed using linear polyethylene bailers, a centrifugal pump, or a <br /> submersible pump depending on yield and depth. The evacuation and sampling equipment that will <br /> contact the water sball be constructed of materials that will not introduce contaminants or alter the <br /> samples chemically in any way. Dedicated linear polyethylene bailers will be used for the sample <br /> collection from each well to be sampled. Purge water will be drummed, labeled and placed in a <br /> designated location at the facility. <br /> Groundwater samples will be collected immediately following purging. In any case, the time <br /> between the completion of the well purging and sampling should not exceed two hours. Samples <br />