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CLEARWATER G R a u r Ena,rornmentai Services Groundwater Monitoring and Sampling Activities On March 7, 2006, Clearwater personnel conducted groundwater-monitoring activities at the above-referenced project site An electronic water level indicator was used to gauge static depth to water, accurate to within f0 01 foot in each of the groundwater monitoring wells The groundwater monitoring wells were checked for the presence of Light Non-Aqueous Phase Liquid (LNAPL) gasoline prior to purging by visually inspecting the electronic water level indicator for the presence of sheen Had sheen been observed a separate phase hydrocarbon meter would have been used to measure the thickness of the LNAPL in the well were sheen was observed In preparation for sampling, the groundwater monitoring wells were purged of groundwater until sampling parameters (temperature, pH, and conductivity) stabilized, this usually occurs with the removal of 3 wet casing volumes Following recovery of water levels to at least 80% of their static levels, each well was monitored for levels of dissolved oxygen (DO), oxidation reduction • potential (ORP), ferrous iron (Fe z+) and total iron (Fe ` "') Groundwater samples were then collected from the wells using disposable polyethylene bailers and transferred to laboratory- supplied containers Sample containers were labeled, documented on a chain-of-custody form, and placed on ice in a cooler for transport to the project laboratory Groundwater samples were analyzed by Kiff Analytical LLC, located in Davis California, a California Department of Health Services-certified laboratory, for concentrations of TPHg, BTEX and MTBE by EPA Method 8260B Monitoring and purging devices were cleaned between uses in an Alconox® wash followed by double rinse in clean tap water prior to placement in each well to prevent possible water quality mfluence from exterior sources, and to prevent cross contamination Purge and rmseate water was collected into a 250-gallon portable holding tank and transported to the Clearwater equipment yard in Pt Richmond, California At the yard the investigation derived waste was then transferred to 55-gallon storage drums pending disposal at the Instrat Disposal Facility • located in Rio Vista, California. ZB1781 2 of 10 May 2006