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1 <br />' GROUNDWATER MONITORING AND SAMPLING PROCEDURES <br /> Groundwater Level Measurements <br /> Groundwater Ievel measurements are obtained during each sampling event at each monitoring well using <br />' a Heron?' interface probe Depth to groundwater at each well is measured from the top and north side of <br /> the well casing Groundwater elevations are based on surveyed well head elevations established at <br />' designated measuring points at the top of each casing The time and measurement are recorded by the <br /> technician <br /> Dissolved Oxygen Level Measurements <br /> ements <br /> Dissolved oxygen level measurements are collected from each monitoring wells immediately after <br /> obtaining the water level measurement The equipment used is a YSI 85 dissolved oxygen meter This is <br /> a hand held meter with a 100-foot code and sensor Typical measurements involve decontamination of <br /> the sensor and the submerged portion of the cord, lowering the sensor into the groundwater approximately <br /> two to five feet, moving of the sensor through the water to obtain the best reading, and recording of the <br /> reading An accurate reading will drop to the lowest level and then fluctuate Readings include dissolved <br /> oxygen as percent, dissolved oxygen in milligrams per liter, conductivity in microsiemens, salinity in <br /> milIisiemens per liter, and temperature degrees Celsius <br /> Groundwater Purging <br /> Based on the groundwater level and the total depth of the well, the volume of water to be purged from the <br /> well is calculated before purging begins Approximately three well volumes are typically evacuated <br /> (purged) from each monitoring well during well purging activities Groundwater is purged from each <br /> well using a pump and reel system consisting of a 2-inch, Geo-Durham submersible pump and teflon— <br /> hose or a new 1 5-inch diameter polyethylene disposable bailer Field data including pH, specific <br /> Iconductance, dissolved oxygen and groundwater temperatures are recorded during water evacuation from <br /> each monitoring well <br /> To minimize the likelihood of cross-contamination occurring, the pump and sampling equipment are <br /> decontaminated prior to commencement of purging activities at the site and between each monitoring <br /> Iwell In addition, the pump and reel system are decontaminated between samples using a non-phosphate <br /> detergent wash, tap water rinse, and final rinse using deionized water Decontamination rinsate is <br /> containerized with the purge water Decontamination and purged water will be temporarily stored in an <br /> appropriate 55-gallon steel drum pending waste profiling, removal and disposal If possible, waste purge <br /> water will be removed using a certified hauling company with a vacuum truck <br /> 1 <br />