ARCHIVED REPORTS_XR0003514 - Laserfiche WebLink

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4 2 1 Monitoring Well Construction, Development.and Survey ' A C- 57 licensed contractor will install the wells to total depths of approximately 55 feet bgs, using ' a truck-mounted drill rig, and 8-inch diameter hollow stem augers The wells will consist of approximately 20 feet of two-inch diameter, Schedule 40, flush-threaded and machine-slotted (0 020-inch) PVC well screen Since groundwater is anticipated at approximately 45 feet bgs, the ' well screen intervals will extend from approximately 35 to 55 feet bgs Blank PVC casings will thread into the tops of the well screens and extend to the surface ' The driller will place filter packs of Monterey#3 graded and washed sand within the annular spaces between the well screens and borehole walls and approximately two feet above the tops of the screens Following the placement of the filter packs and prior to the installation of the well seals, the driller will develop the wells by the surge and purge method Periodic surging and ' purging of each well will continue, until at least five well volumes have been removed Overlying the filter packs, the driller will place two feet of hydrated bentonite within the annular ' spaces Over the hydrated bentonite, the driller will install surface seals of neat cement grout The wellheads will be secured with watertight locking caps and traffic-rated, flush-mount boxes A licensed land surveyor will survey each of the newly-installed wellheads The surveyor will measure the elevations of the tops of well casings to the nearest 0 01 foot, referenced to a ' benchmark The locations of the wells and other site features will also be surveyed 4 2 2 Soil Sampling and Analysis During drilling, undisturbed soil samples will be collected at five-foot intervals using a modified California split-spoon sampler, lined with two-inch diameter by six-inch long brass or stainless steel sample sleeves A field geologist will log each of the undisturbed soil samples for hydrogeologic and lithologic characteristics according to the Unified Soil Classification System, ' and screen each sample for any organic vapors using a photoionization detector (PID) To further evaluate the lateral extent of impacted soil, the soil samples collected from the groundwater table interface (45 feet) and the total depth of the well borings (55 feet) will be submitted for laboratory analysis Additional soil samples may be submitted for analysis, if necessary to characterize subsurface conditions Field observations and sample selection will be reviewed with the EHD inspector, prior to sample submittal to the lab 12