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Groundwater Monitoring <br /> Well Installation and <br /> �► ARCADIS Sampling Work Plan <br /> PG&E McDonald Island <br /> Compressor Station <br /> • Reduction/Oxidation potential to within 10 millivolts <br /> 3.5 Monitoring Well Survey <br /> The top of casing and ground surface elevation, as well as the northing and easting for <br /> the new monitoring wells,will be surveyed by a California-licensed land surveyor after <br /> completion of the monitoring well installation. <br /> 3.6 Monitoring Well Sampling <br /> The wells will be sampled using low-flow sampling techniques. To measure <br /> groundwater elevation,the monitoring wells will be gauged prior to initiating sampling <br /> activities. The monitoring wells will then be purged at a rate of no more than 500 <br /> milliliters per minute(mUmin)using a decontaminated QED MP-10 bladder pump(or <br /> similar)until field parameters(including pH, temperature,conductivity, and turbidity) <br /> have stabilized as defined in the well development procedures above. In the event that <br /> the well does not recharge at a sufficient rate to support low-flow sampling,the well will <br /> be purged dry and allowed to recharge to 80 percent of its original water column prior <br /> to sampling.After purging activities are complete,groundwater samples will be <br /> collected through the pump into laboratory-supplied sample containers. <br /> The groundwater samples will be sealed, labeled, placed in an ice-chilled cooler and <br /> submitted to Calscience Environmental Laboratories(Calscience), a Califomia <br /> Department of Public Health-certified analytical laboratory located in Garden Grove, <br /> California, under proper chain of custody procedures for the following analyses: <br /> • TPH-d by USEPA Method 8015B(M)with and without Silica Gel Treatment(SGT) <br /> • Naphthalene by USEPA Method 8260B <br /> • Methyl tert-butyl ether(MTBE)by USEPA Method 8260B <br /> The groundwater samples will be analyzed with and without SGT to evaluate whether <br /> any interference from naturally occurring polar compounds exists. <br /> 3.7 Decontamination <br /> All down-hole drilling and sampling equipment will be steam-cleaned prior to <br /> deployment and following the completion of the sampling location. Decontamination of <br /> non-dedicated or non-disposable field equipment will be conducted using an Alconox® <br /> solution and deionized water rinse to prevent potential cross-contamination. <br /> Mcdonald Island Addtl MW Installation Work Plan Doc, 7 <br />