ARCHIVED REPORTS XR0009635 - Laserfiche WebLink

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City of Stockton A 68104 OIA October 25, 1995 Page A-5 Some monitoring wells are expected to be evacuated to dryness after removing fewer than three casing volumes These low-yield monitoring wells are allowed to recharge for as long as 24 hours Samples are collected as soon as the monitoring wells have recharged sufficiently to allow sample collection. If insufficient water has recharged after 24 hours, the monitoring well is recorded as "dry" for the sampling event Purged water is containerized in Department of Transportatio n-approved drums, and stored on site in an area inaccessible to the general public The purged water is typically characterized wither by sampling it, or on the basis of the groundwater sample analytical results Twining can recommend an appropriate method for disposition of the purged water Disposal will be the responsibility of the client Water samples are transferred into sample containers supplied by the analytical laboratory Sample containers are labelled and placed in an ice-cooled chest, equipped with a thermometer, for transport to the laboratory The temperature inside the ice-cooled chest are recorded on chain of custody documents when samples are placed in the chest, and when they are received by the laboratory Samples will be maintained at a temperature of approximately 4 degrees Centigrade A-5 Decontamination Decontamination procedures are implemented to reduce the potential for cross-contamination between soil borings Before, during, and following drilling operations, the augers and associated drilling and sampling equipment are thoroughly cleaned using a high pressure hot water (steam) washer The hot water washer has a pressure of approximately 1,200 pounds per square inch and a water temperature of approximately 100 degrees Centigrade ("C) The sampler and sleeves are washed in a AlconoxO detergent solution, rinsed with clean tap water, and air-dried prior to iratial use and between each sampling event The augers are steam cleaned prior to the drilling of each soil boring Prior to construction of monitoring wells, all casings are cleaned in the same manner as the drilling equipment A-6 Sample Handling and Chain-of-Custod Records are developed for soil and groundwater samples including sampling date, sample type, location, depth, job number, name of sampling personnel, and method of preservation Each sample container is labelled immediately following collection in the field Chain-of-custody protocol, described in United States Environmental Protection Agency (U S EPA), 1986, Test Methods for Evaluatin Solid Waste, SW-846, 3rd edition, is followed Samples are placed in an ice chest and maintained at approximately 4'C until they are delivered to the laboratory The temperature within the ice chest is monitored and recorded during the course of transport and delivery Samples are accompanied by proper chain-of-custody documentation Upon arrival at the laboratory, the samples are preserved for analysis in accordance with U S EPA and state of California requirements Samples are delivered to Twining's chemistry