|
' 5440-5606 Pacific Avenue -2- 4 October 2004
<br /> Stockton, San Joaquin County
<br /> contaminant distribution in deeper aquifer zones Also,there appears to be some recent plume movement
<br /> in shallow groundwater to the north and east of 5606 Pacific Avenue
<br /> By 15 November 2004, submit a geochemical evaluation(GE)report signed by a geochemist, which
<br /> compares the results of the soil and groundwater analyses,and thoroughly discusses the expected worst-
<br /> case scenario reactions,i e, 100%conversion of constituents of concern into contaminants,reporting the
<br />' chemical reactions in molar concentrations
<br /> 1 If metals of concern(Cr"",etc)are not detected,or general minerals (SO4,etc)are not present at
<br /> levels favorable for adverse reactions in saturated soil,then submit a Pilot Study Workplan with the
<br /> GE Report Note that all Pilot Study analytical detection hnuts must be sufficiently low to test the
<br /> theories proposed in the GE Report and provide comparisons to Water Quality Objectives You will
<br /> continue to monitor groundwater during the Pilot Study for the know petroleum.hydrocarbon
<br /> 1 contaminants and general parameters(dissolved oxygen,pH,specific conductance,temperature)
<br /> 2 If metals of concern(Cry,etc)are detected,or nunerals of concern (SO4,efc)are detected at
<br />' potentially harmful levels,then include a Workplan for a Bench Scale Test(BST)with the GE report
<br /> The BST should show which contammant(s)are produced and whether the produced contammant(s)
<br /> will persist after termination of oxygen infection,using the graphed slope of the declining
<br /> contaminant(s) concentrations versus time to calculate a decay rate(time to revert to non-detect) If a
<br /> contammant(s)is produced and persistent,provide that information in the BST report for my
<br /> evaluation If contaminants)produced are not persistent,provide Workplan for the Pilot Study with
<br /> the BST Report containing modifications to the Pilot Study monitoring program, specifically,the
<br /> frequency of analyses needed to confirm contaminant decay rates as calculated from BST analytical
<br /> evidence
<br /> O By 15 December 2004,begin the Pilot Study During the Pilot Study phase,groundwater sampling and
<br /> analyses will be conducted,at a mmi num,immediately before startup of the ozone injection system,and
<br /> at intervals of one and 2 hours afterwards, in order to validate all contanunant(s)analyses and proposed
<br /> 1 I decay rates,if applicable If a BST is not required prior to the Pilot Study, then, at a minimum,analyze
<br /> I at least once before and 1 hour after startup of ozone injection
<br /> c Install automated data loggers in selected monntonng well(s)to record changes in dissolved oxygen,pH,
<br /> j specific conductance, and temperature during the Pilot Study The test data will be helpful to determine
<br /> the effectiveness of ozone injection
<br /> You may call me at(916) 464-4615 for questions or additional information
<br /> LAME
<br /> S L BARTON,R G
<br /> i
<br /> Engineering Geologist
<br />] cc Mr Mark Owens,UST Cleanup Fund, SWRCB, Sacramento
<br /> Mr Mike Infuma, San Joaquin County Environmental Health Division, Stockton
<br /> 1:K.� Jill Tracy,Esq,UNOCAL,Brea
<br /> Mr Ben Hennmgburg, ENSR International, Sacramento
<br /> Mr Gary Hall, GHH Environmental, Auburn
<br /> i
<br />' 0
<br /> —I
<br />
|