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CALIFORNIA GEOPHYSICAL GROUP, INC. FO—Box 578341 Modesto, CA 95357 Tel (209) 527-1247 Fox (209) 527-4810 ' QUALITY ASSURANCE/QUALITY CONTROL PROTOCOLS 2006 GROUNDWATER MONITORING SAMPLING When the technician arrives at a site for a quarterly sampling the first thing done is to locate each well Standard operating procedures to minimize cross contamination, are to work from the cleanest potential monitoring point progressively to the highest possible contaminated location(s) All monitoring well extenors should be cleaned prior to opening the well, orange salty cones are placed in the proper position before starting to work ' The monitoring well boxes are opened and unlocked and the well cap is placed back on the well head very loosely to allow the static water level to stabilize If the well boxes ' have any standing water that is pumped out before starting the sampling After the well head screening is completed, the opened wells have allowed the water within the casing time to stabilize to the surface atmospheric pressure The breathing time also allows any trapped gas to expel and reduce the chance of any exposure to the sampling technician All of the monitoring wells are measured to one hundredth of an inch, for the static standing depth to water with a solinist depth to water meter and then the total depth is measured of each well We take the depth of the well and water from the high point of the casing of each well Decontamination is completed at each well to the measuring tape A spray bottle with alconox soap and a spray bottle with clean nnse water is used to complete the task During the purging of the well the sample integrity is always considered You should attempt to purge the well without stressing the subsurface static conditions As each well casing volume is removed the PH, temperature, conductivity, oxygen levels and odor is monitored and recorded on the smpling sheet Del-Tech, the subcontractor for California Geophysical Group, Inc (CGG) uses the ' waterra method with a dedicated waterra inertia pumping unit Each well has its own dedicated tubing so there is no cross contamination between wells The waterra system withdraws the water from the area of the slotted casing All field equipment ' used during any monitoring event will be cleaned by steaming or washing with TSP and cleaned inside with a special brush After the washing, all equipment will be rinsed with clean water to be sure that it is free of any soaps, etc ' Each well is purged at a steady flow rate The goal is to not over stress or draw down the water formation within the well casing and to establish a smooth lateral flow through the well screen interval Each well should be purged for a proposed minimum of three ' calculated casing purge volumes Ir