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Groundwater Quality Sampling Plan <br /> development will consist of purging a minimum of five casing volumes from the well, or <br /> purging the well dry twice if the yield is insufficient for continuous purging. In wells with <br /> sufficient yield, purging will continue until the sediment is removed and field parameters <br /> (pH, temperature, and conductivity) stabilize. Parameters are considered stabilized <br /> when there is less than a ±10 percent change in three consecutive measurements of <br /> temperature and conductivity, and pH readings are within ±0.2 standard units. For wells <br /> that purge dry, field parameters will be measured at the start and end of both purging <br /> cycles, if possible. <br /> The volume of water standing in each well will be calculated using the static water level <br /> measurement, the total depth of the well, and the casing diameter. One casing volume <br /> will be considered the water present in the well casing. Well depths for the purpose of <br /> well volume determination will be obtained from well completion records. The equation <br /> for calculation of one casing volume is: <br /> V = [rrx (r )2xh]x7.48 <br /> V =0.16xh for a2 inch well <br /> where: <br /> V = volume of water in well casing [gallons] <br /> r casing= radius of well casing[feet] <br /> h = height of water column (total well depth -depth to water) [feet] <br /> 4.3 Sample Collection <br /> 4.3.1 Decontamination <br /> All re-useable, non-dedicated sampling equipment will be decontaminated <br /> between each well location to provide representative samples. Decontamination <br /> will be performed by washing all equipment with an AlconoxTN/water solution <br /> followed by a rinse with distilled water. Water generated from decontamination <br /> procedures will be disposed of at least 20 feet from the well site. All clean or <br /> unused sampling equipment will be handled by personnel wearing new <br /> disposable gloves (e.g., nitrile or latex). After the re-useable sampling equipment <br /> has been decontaminated it will be wrapped in new clean plastic sheeting or <br /> placed in new clean plastic bags. The sampling equipment will remain in plastic <br /> sheeting or bags until it is used again at the next sampling event. <br /> 4.3.2 Sampling Equipment and Materials <br /> Purging and sampling equipment will consist of bailers and/or pumps. The bailers <br /> may be disposable or dedicated, and the pumps either dedicated or re-useable, <br /> to be decontaminated prior to each sample location, or dedicated. This <br /> MOLEN&ASSOCIATES LG Everist Sampling Plan <br /> Page 4 of 10 <br /> 43 <br />