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.HORIZON ENVIRONMENTAL INC. - GROUNDWATER MONITORING FIELD METHODS AND PROCEDURES The following section describes field procedures that will be conducted by Horizon Environmental Inc. (Horizon) personnel in performance of the tasks involved with this project. 1.0 HEALTH AND SAFETY PLAN Fieldwork performed by Horizon and subcontractors at the site will be conducted according to guidelines established in a Site Health and Safety Plan (SHSP). The SHSP is a document that describes the hazards that may be encountered in the field and specifies personal protective equipment, work procedures, and emergency information. A copy of the SHSP will be at the site and available for reference by appropriate parties during work at the site. The site health and safety plan shall comply with health and safety guidelines in the Horizon Health and Safety Program Handbook. - 2.0 GROUNDWATER DEPTH EVALUATION Each monitoring well is opened and allowed to equalize to atmospheric pressure prior to sounding. Depth - to -water is measured to the nearest 0.01 -foot using an electronic, hand-held, water -level indicator. The measuring point is the survey mark on the top of the well casing. The tip of the probe is examined in order to evaluate for the presence or absence of separate—phase product (SPP). 3.0 MONITORING WELL PURGING & SAMPLING Prior to purging, a clean, transparent bailer is lowered into the well, and a sample of groundwater is hoisted to the surface. The sample fluid is inspected for the presence of SPP on its surface. if no SPP is observed, sampling activities conducted subsequent to the initial well development activity will be preceded by purging a minimum of three well volumes by hand -bailing or the use of an electrically -operated pump. Purge water will be containerized in properly labeled drums or tanks for proper transport from the site and disposal. Purge water will be monitored for the parameters of temperature, pH, and electrical conductivity until stabilized or the completion of the calculated purge volume. If required, field readings for dissolved oxygen (d02), recorded to one decimal place, will be obtained utilizing hand-held instruments. If SPP is observed, then either an interface probe will be lowered into the well to measure the thickness of the separate -phase liquid fuel, or a disposable plastic bailer will be lowered into the well approximately 1/2 to % way through the air- SPP -water interface, and hoisted to the surface to measure the thickness of the separate -phase liquid fuel in the bailer. A well is allowed to recharge to at least 80% of its pre -purge volume prior to sampling. If a well dewaters, it will be allowed to recharge for a minimum of one to two hours prior to sampling. After the water level within the well has stabilized or a reasonable time has passed, a sample is collected within a clean, disposable, bailer lowered into the well approximately '/Z to -1/, way through the air water interface and hoisted to the surface. Water samples will be transferred directly from the bailer to laboratory -supplied appropriate containers, labeled, stored in a chilled environment (cooler), and transported to a California DHS -certified laboratory for analysis. Samples will be analyzed within the EPA -specified holding time for the requested analysis. Each sample container submitted for analysis will have a label affixed to identify the job number, sample date, time of sample collection, and a sample number unique to that sample. A chain -of -custody form will be used to record possession of the sample from time of collection to its arrival at the laboratory. When the samples are shipped, the responsible technician or geologist relinquishes custody of the samples by signing the chain -of -custody form, noting the date and time. The sample -control officer at the laboratory: • verifies sample integrity; • confirms storage in the proper container; • recognizes that an adequate volume of fluid has been collected for the required analysis; • identifies the method of preservation; and • accepts custody for the laboratory when these conditions have been satisfied. Revised/updated 812011