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,M Texaco Environmental Services September 12, 7991 02320 1700 Page 4 3.5 MONITORING WELL DEVELOPMENT Subsequent to installation,the monitoring wells will be develfned manually using the surge and ball technique. Approximately three to fire well volumes of water will be extracted from each well by this method. This technique Is used to remove the fines left from drilling,to create an even sand pack,and to rehabilitate the borehole sides. The to es are drawn through the well screen and subsequently balled from the well. This process Is repeated until the water is visibly clear of fines. Subsequent to development,the wells will be left undisturbed until water levels reach equilibrium. Prior to groundwater monitoring and sampling,the wellheads will also be surveyed. 3.6 GROUNDWATER MONITORING Prior to sampling, the monitoring wells will be gauged using an QRS Environmental Equlpmv;It INTERFACE PROBE-to determine depth to water(OTW),and to check for the presence of separate-phase hydrocarbons(SP). The DTW Information will be used to construct a potentiometric surfacq elevation map and to determine the hydraulic gradient. 3.7 GROUNDWATER SAMPLING After groundwater monitoring,the monitoring wells wil;be purged of a sufficient water volume to assure a representative sample. Sampleswill then be collected using a TeflonA sampler cleaned with an ' Industrial detergent and distilled water. The water samples will be poured from the sampler Into appropriate IMI containers,acidified when nece3sary,labeled and placed on ice in an insulated container for delivery to a State of Califnmia-o`tied laboratory. The samples will be accompanied by a chain-ef-custody manifest and will be analyzed fc�rTPH-G and BTF_X by modified EPA methods 503ri/8020/8015. 3.8 SOIL.AND WATER DISPOSAL Sall cuttings ge%.ated during the course of drilling will be stored on and covered with heavy plasr;c sheeting psading laboratory analyses. Soil disposal will be the responsibility of the client/generator. Wastewater generated from steam cleaning of drilling augers and from monf4oring•wetl development and purging will be collected and stored on site in Department of Transportation(DOT)-approved 55-gallon drums, ponding disposal at an EPA.-permitted transport,storage and disposal facility,or discharged under the appropriate permits. Wastewater disposal will be the responsibility of the ci€ent/generator. GRoU\I3LMI'M i7oavrlwzRar [mmoi.ocy 1,Nc.