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- r L Fi:,No.2070-2 I9 December 1991 � Pse S advanced to a depth of 60 feet utilizing eight inch, hollow stem, flighted augers driven by a truck- mounted drill rig. Subsurface soil conditions were logged by an onsite geologist during advancement ot'the well boring (see Appendix III for the boring log). Two inch diameter schedule 40 FVC well casing was hen installed and the well constructed as detailed in the well construction diagram of Figure 5. Soil cuttings derived from the drilling of the well borings were containerized in 55-gallon _ drums. The drums were stored on the siie pending laboratory analyses determining whether ' atamination was detected, rollnwing well devzlopmen Appendix VI for monitoring well development 'roundwater sample was ovt,��m:d from MW-8 (sea Appendix VII forgroundwater r d procedure a ng —)cerium) and analyzed by a State of California certified analytical laboratory afo he presen ellf of TPH, "• 's and lead. No TPH, AVO's or lead were detected in the groundwater sample obtained �- Econ '-8. Therefore, MW-8 allowed a down-gradient 'zero line' of contamination to be estab,,. and subsequently is the down-gradient control well. Static groundwater level measurements were then obtained for aJi eight onsite monitoring wells. Calculations verified that the local groundwater gradient tended toward the east/northeast as determined during previous calculations (see Appendix V for groundwater gradient calculation procedure). Figure 6 illustrates the direction& of the local groundwater gradient calculated for the subject site over the last several years. 2.4 Performance of Well Pumping Test A well purtping test was performed for the Rainbo Bakery site by ACG on 1 I and 12 June 19991. Ilia objective of the well pumping test was two-fold; 1) to determine the hydraulic characteristics of the local aquifer in which die contaminated groundwater is contained, and 2) to determine the effective zone of influence of the designated pumping well, 71e well pumping test was performed by continuously extracting groundwater from. one well (termed the pumping well) while monitoring groundwater levels in neighboring wells (termed obseavation wells). An observation well which exhibited drawdown (a drop in the local groundwater : table level) during the well pumping test was determined to be contained within the zone of influence of the pumped well. In other words, the pumped well creates a localized cone of ` depression. Observation wells which experienced a drop in their groundwater level during the well pumOng test were determined to be influenced by the pumped well's cone of depression. For the %yell pumping test, ASW-1, located in the center of he contaminant plume, was utilized as the pumping well. M-2, MW-3, MW-4, MW-6 and MW-8 were utilized as observation wells (MW-5 and MW-7 could not be rased sire the elevatit n of the local groundwater table was below the bases of these two wells at the time of the well pumping test). An average discharge rate of y 6.7 gallons per minute (gprti) of groundwater was continuously extracted from MW-I during he well _., pumping test. Drawdown in MW-I was continuously recorded during the well pumping test utilizing a computerized •data jogger. Drawdown in he five observation wells was continuously ren;orded at regular intervals utilizing a handheld groundwater probe. i The well pumping test was conducted for a duration of 24 hours. Fol)nwing completion of the well } � ANDERSON CoNSULnya caoua i l`