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OR -t EOB and organic lead were none detacted for each of the eight soil samples. . . The second sampling was completed on October 4. J989. Groundwater monitoring wells were developed and initially sampled approximately two weeks after completion. Ground water J samples were sent to a State certified laboratory for analyses. Ground water samples from the two up-gradient wells(MW-2 and MW-3)were none detected for total hydrocarbons and 13TX. However, analyses of the ground water samples from the down-gradient monitoring well (MW 1) detected total hydrocarbons at 4,300 ugrl, benzene at 250 U90, ethyl benzene 30 ugll and xylenes at 280 ugfl from the first sampling (June 19$9), and benzene at $82 ugll, xylenes at 151 ugll and total hydrocarbons at 574 ugll ffom the second sampling (October 1969). EBMUD removed the two remaining underground fuel storage tanks in September 1989. Kleinfelder understands that laboratory data from the soil samples bonsacollected e a alytthe removed tanks indicated that the soils did not contain by ical -site observations and lank tests did not indicate past fuel method detection levels. On leakage from these two tanks. r � 1.2 P In February 1991, at the direction of EBMUD, WESTON submitted a Work Plan to the EHD for an additional soil and groundwater investigation at the EBMUD site. The investigation plan consisted of the insta-llation and development of four additional groundwater monitoring wells on the site, soil sampling from the four well borings and sampling and analysis of groundwater from all seven (the three previously installed and the four new) monitoring wells. The Work Plan was approved and the well permits were issued by the EHD. Field work took place in February and March 1951. 1.3 ort tllZlon EBMUD maintains an operations and maintttrta;,ce yard at 1604 West Main Street in Stockton, California (Figure 2). The site is Oonupied by buildings used as offices, mainte- nance garages, and supply and equipment storage areas. Vehicles are currently refueled in the yard from new, above ground storage tanks. The yard is essentially flat and is situated in an area of mixed residential and industrial use. e Th Porteet of Stockton ttt of the yard.the Stockton deep water channel are located approximately 1 2.0 1991 INVESTIGATION 2.1 Mon itodag-WBILlistakka In February 1991,four monitoring wells(MW-4, MW-5, MW-6 and MW-7)were installed in addition to the three wells already on the site. The purpose of the four new wells was to establish additional groundwater monitoring points,three in the downgradient direction re Jinn - (MW4ra ndwaterr qualitytdat the a degradient or grou dwatetr flow grad ent indirection format on.)by p 9 both g E i < - 3 -