SITE INFORMATION AND CORRESPONDENCE

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Ms. Mary Meats -_ Page 4 February 25, 1995, - - -were measured afMW-_1A 5.0 feet below grade: No detectable petroleum l constituents were:detected in any samples below a'depth of 7.5 feet below grade. -.Based on' the information-obtained, ERM conservatively estimates=that the maximum vertical-extent of detectable .TPH-6,;'_TPH O and benzene_ in the - soil at Site #2:is-approximateiy 12.feet below grade. No TPH-G, TPH-D or-BT-EX were detected ih-any.of the soil samples.taken. M from W-4A,.-located south of-the tank excavation under.the warehouse building. =Consequently, this.well=.constrains-the literal distance south `of the the -where detectable quantities=of these petroleu 'compounds will be; found in soils to .the.-.-For a worst case-scenario,'tlie.maximum lateral extent of detectable TPH-G,_TPH-D or BTEX-compounds underneath the building would be situated immediately adjacent-:to-"and north of MW-4A. In this .scenario, the .maximum lateral distance where detectable hydrocarbon compounds could..be present in the soils=_underne'ath.:the building would-be approximately_30.. feet from the.edgeof'tl e-excavation.-It -is more'-likely that . the actual=distance is-'less than 30-feet. Based`on;this--information,'we believe that the maximum'lateral extent-,of petroleum compounds in-the soil- underneath the warehouse building-has.been. adequately defined. However; - - _ - the lateral extent'of.'petroleur.n 'compounds-in soil located to the north and east-of the tank excavation has not yet been frilly &fined.at this tir; e'. Groundwater Groundwater-at-Site #2 has been.chara:cterized b" the analysis of data obtained. from the tank excavation;-aiid_4 groundwater monitoring-wells. As discussed" _previously, -confined ground__wa.-ter..conditions..were encountered during-the- "drilling- uring-the "drilling-of-MW=1A,'MW-3A arid-MW--4A. During the installation of each-of the wells, we drilled=.'through:unsatuiated.silty.and'_clayey soils prior to- encountering_groundw'ater'witl in sandy soils. After-encountering-the- . groundwater during-drilling; water elevations°in the wells rose by=4 5_to-_15.5 feet in -the wells:. =Subsequent quarterly groundwater..measuiements have not indicated any-water level measurements at_depths where they were originally encountered during 'the drilling of'the wells _.It appears that the groundwater in the-sandy soils is-confined by the silty/clay-layer,overlying it, _The water levels in MW-1A, MW-3A and MW-4A are above the water-bearing,zone and define'the .potentiomefric-sur..face. - ERM and.Catellus_believe_that-MW-3A-and MW-4A are ,properly screened: The screened intervals-"in MW--3A.and-MW4A were chosen below the top of- the potentiometric:.sur#ace to. protect-uncontaminated soils around--the " building from the-possibility ofbeing contaminated-by..groundwater which rises from the confined aquifer. This,decision is strengthened.by the fact that.-',. laboratory test.results show that there are interval sin these wells in which.no