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i <br /> and blank casings used were flush-threaded and no chemical cements, glues or <br /> solvents were used in the well construction <br /> The annular space between the casing and the formation was filled with a sand <br /> filter pack of clean, sorted #3 Monterey sand The sand filter packs extend 6" to <br /> 1 foot above the top of the well screens A seal consisting of one foot of medium <br /> sized bentonite chips was placed above the filter pack in each well The bentonite <br /> chips were Hydrated with clean water to cause expansion which provides the sealing <br /> effect The remainder of the annular space above the bentonite seal was filled with <br /> neat cement within one foot of the ground surface The top of the casing was fitted <br /> with locking caps and encased in a traffic-rated, flush-mounted metal manhole or <br /> well cover After the monitoring wells were completed, they were surveyed by a <br /> licensed surveyor (see Appendix I, Boring Location Survey Map) The surveyed <br /> elevations confirmed that the groundwater gradient is to the northeast <br /> 7.3.1 Monitoring Well Development <br /> The wells were developed a minimum of 48 hours after installation Well <br /> development was performed for two basic reasons The first reason is to <br /> remove the clay layer formed on the face of the aquifer caused by the <br /> drilling process The second is to remove the fine particles in the natural <br /> formation to increase the permeability of the formation near the borehole <br /> i This is performed to establish hydraulic communication between the well <br /> and the aquifer <br /> Prior to development, the depth of the groundwater was measured with an <br /> electronic water level indicator Well development was performed using <br /> a development pump The well development was accomplished by surging <br /> and swabbing with a surge block and pumping Approximately fifty-five <br /> (55) gallons of development water was purged from each well The amount <br /> of water extracted depended on how well the formation water cleared up <br /> during purging The purge waters were stored on-site in 55-gallon steel <br /> drums pending disposal based upon results of laboratory analyses The <br /> purge waters were then removed from the subject property under chain of <br /> custody using a non-hazardous waste manifest for final disposition at <br /> McKittnck Waste Treatment Facility in McKtttnck, California (See Waste <br /> Manifest Appendix VI) <br /> Groundwater samples were collected at least 24 hours after the wells were <br /> developed Prior to purging, the depth of the groundwater in each well was <br /> measured to the nearest 0 01 foot Each well was purged by pumping out <br /> a minimum of 3 times the volume of the water column of the well Water <br /> parameters such as pH, temperature and conductivity were monitored <br /> during purging to determine if the parameters were stabilizing during the <br /> CRC Environmental Risk Management Inc Project M 3620-001-4 <br /> George Bravanu: Receiver 2233 Grand Canal Boulevard <br /> January 19 1995 11 Stockton California <br />