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- HORIZON ENVIRONMENTAL, INC. GROUNDWATER MONITORING FIELD METHODS AND PROCEDURES The following section describes field procedures that will be completed by Horizon Environmental Inc. (Horizon) personnel in performance of the tasks involved with this project. 1.0 HEALTH AND SAFETY PLAN Field work 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 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. 2.0 GROUNDWATER DEPTH EVALUATION Each monitoring well is opened and allowed to equalize ti 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 determine the presence or absence of product sheen. 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 free-floating product on its surface. 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 monitored for the parameters of temperature, pH, and electrical conductivity until stabilized. If required, field readings for dissolved oxygen (d02), displayed in tenths of parts per million (ppm x 0.1), will be obtained utilizing Hanna Instruments' hand-held, HI-9142 Portable Dissolved Oxygen Meter. Generally, higher d02 concentrations are expected in samples, which are unimpacted or marginally impacted by hydrocarbons than for samples collected from monitoring wells which yield hydrocarbon-impacted water. A well is allowed to recharge to at least 80% of its prepurge 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, a sample is collected within a dedicated, clean, disposable, plastic bailer lowered into the well and hoisted when filled. 4,0 SAMPLE PREPARAT# NALYSIS Samples will be transferred to airtight vials, chilled on ice, and transported to a California DoHS-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.