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iuf °1 * 1 iA T F ENE 4 f File No.2070•2 19 December 1991 page 5 advanced to a depth of 60 feet utilizing eight inch,hollow stem, flighted augers driven by a truck- mounud drill rig. Subsurface soil conditions werz logged by:in onsite geologist during advancement of the well boring (see Appendix III for the boring log). Two inch diameter schedule 40 PVC well casing wars then installed and the well colutruct-d as derailed 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 s,'te p,-;,ding laboratory analyses determilling >khevti'T contamination was detected. Following well development (see Appendix VI for monitoring well development procedure), at groundwater sample was obtained from M,'s 4 {;ee Appendix VII for groundwater sampling procedure) and analyzed by a State of Caliibmla cci=Afied analytical laboratory for the presence of TPH, AVO's and lead. No TPH, AVO's or';ead were detected in the groundwater sample obtained from MW-8. T",lerefore, M%V-8 al'owed a down-gradient "zero line" of contamination to be established .and subsequez-aly is the down-gmMent control well. Static ,roundwv.ter level meat^:re;nents were then obtained for all eight onsite monitoring wells. ' 'water gradient tended toward 'u'le east/northeast asCalcu[atio►s verified t determined, during previous calcs,,watioils (see Appendix V for groundwater gradient calculation procedure, Figure 6 illustrates-pie directions of the local groundwater .gradient calculated for the subject site over the las?. several yeam;. _.h. 2.4 Performance :r:Well r:.,mpi.71g 'fest A well punipiog test wtas performed for :1'ie Rainbo Bakery site by ACG on 11 and 12 June 1991. The objective of the 'c.'eEl pw aping test was two-fold; I) to determine the hydraulic characteristics of the local aquifer' in whir'• the contan in*ed groundwater is contained, a>]d 2} to determine the ,} rf ective zone a influence of the des'sgnr'--;d pumping well. Tl.~ well pl aslping t.3t was performed by continuously extracting groundwater .from one well ;termed the.pule-*' well) while monitoring groundwater levels in neighboring wells (termed ` observation -wells). An observation well whiff exhibited drawdown (a drop in the local groundwater table level) durh:4, the well pumping test was determined to be contained within the zone of infh ,e of the pumped well. In other words, the pumped well creates a localized cone of observation wells wh ch experienced a drop in their groundwater level during the well pumping =.st were determined to be influen.W by the pumped well's cone of depression. Far the well pumping test, MW-1, located in `lee center of the contaminant plume, was utilized as . a ttilized �u observation wells VN-�6 and M'�'J-R w.r l pumping well. MW-2, MW-3, h'IW�. h ., (MW and Mti3!-7 could not be used. since the elevation of the loal groundwpter table was below s, the bases of these two wells at the time of the well pumping test). Average {discharge rata of 6.7 gallons per minute (gpm) of groundwater wa3 continuously extracted from MW•1 during the well pumping test. Drawdown in MWA was contificuusly recorded durinE.;the well pv nping test uti,izing a cocnputprize -data logger. Drawdown in the five observation wells was cc',',3nuously recorded at regular intervais utilizing a handheld groundwater probe. the »411 pumping test was conducted for a drration of 24 hears. Fallowing completion of the well ANp€AEON GROUP i f '