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Mr. Kyle Christie March 9, 1990 Page 4 well W-8 was not sampled as dissolved hydrocarbons have never been identified in groundwater samples from monitoring well W-8,and it is located some distance from any identified dissolved hydrocarbon occurrence. Monitoring well W-213 was not sampled during August 1989. Field Methods, September 1989 Prior to sample collection, groundwater was purged from well W-213 by bailing with a stainless steel bailer. The pH and specific conductance of the discharge water were monitored. Approximately three well volumes of groundwater(one well volume being the volume of water inside the casing plus 35 percent of the gravel packed annular space)were evacuated. The well was sampled with a teflon bailer equipped with a bottom-emptying valve. The sample was drained directly from the bottom valve into two 40-milliliter glass bottles with 'Teflon- lined septums. The samples were stored on ice from the time of collection through delivery to Eureka Laboratories, Inc., in Sacramento. All purging and sampling equipment was washed with laboratory-grade detergent and tap water, then rinsed with deionized water before each use. Field and Analytical Results, August and September 1989 f f Depth to groundwater was approximately 49 feet below ground surface in April 1987,when the first three monitoring wells were installed. Water level measurements show that groundwater t beneath the site rises somewhat in the winter months but is declining overall. Depth to groundwater was approximately 61 feet in August and September 1989 and groundwater flow t direction was to the west-southwest. - I Dissolved BETX concentrations in groundwater samples collected from April 1987 through Octol er 1989 are suuunarized in Table 1. Complete laboratory reports of the September 1989 groundwater sample analysis of well W-213 are enclosed as Exhibit A. In September 1989, I xylene[at a concentration of 1.0 parts per billion(ppb)] was the only BETX constituent detected its .-,ell Field Methods - October 1989 Prior to sample collection, groundwater was purged by pumping from each monitoring well by Armour Petroleum,Inc.,(Armour)of Fairfield,California. The pH and specific conductance of the discharge water were monitored. Three well volumes of groundwater were evacuated from monitoring wells W-2, W-2B,W-3, W-5, W-6, and W-7. In October 1989(see Figure 2), the W 4 was difficult due to the slow recharge of purging of monitoring wells W 2A and g groundwater. Therefore, I and 1.4 well volumes,respectively,were evacuated from these wells. T Sample collection, storage, and transportation procedures, as well as sample equipment decontamination procedures,were the same as those used in September 1989. All groundwater produced during purging and sampling was disposed of by Armour. i Brawn and Calftell Consult,