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Or. Mike Desso - 2 - 14 May 2007 <br /> Nestle USA Inc. <br /> show that TCE in the subsurface beneath the Former Facility is primarily present in groundwater, <br /> not in soil, Nestle will not implement Phase 2. However, if the apparent source of TCE is <br /> identified in soil during Phase 1, Phase 2 will proceed and additional soil data will be collected. <br /> Concentration data on TCE in soil obtained during Phases 1 and 2 will aid Nestle in the <br /> evaluation and selection of appropriate interim remedial action technologies to reduce <br /> concentrations of TCE beneath the Former Facility. <br /> Regional Water Board Review Comments <br /> 1) During Phase 1, Nestle intends to advance borings B-4 and HP-3 between the <br /> Former Facility processing area (assumed release area) and the area of elevated TCE <br /> concentrations in groundwater identified during the 2005 Geomatrix Consultants, Inc., <br /> investigation summarized above. The Work Plan proposes to collect soil samples <br /> throughout the boring interval, but the only groundwater samples would be collected within <br /> the sandy layer below the contact with the overlying clay layer at approximately 50 feet <br /> bgs. Regional Water Board staff notes that groundwater samples from sandy intervals <br /> above the clay layer were not collected in borings CPT-8, CPT-9, and CPT-10, located in <br /> the vicinity of proposed borings B-4 and HP-3. Also, existing groundwater monitoring well <br /> M-1 2A is screened below this contact between 89 and 109 feet bgs. To investigate the <br /> possibility that TCE concentrations in shallow groundwater exist in this area, Nestle should <br /> additionally collect groundwater samples from within sandy layers above the clay layer. <br /> 2) In Section 3.4.1, Nestle proposes to screen soil core intervals with a photoionization <br /> detector from the surface to the water table, the clay layer between approximately <br /> 40 to 50 feet bgs, and the sandy layer between approximately 50 to 60 feet bgs. <br /> However, the interval between the water table and the top of the clay at approximately <br /> 40 feet bgs should also be screened since TCE may be present within the saturated soils. <br /> 3) The Work Plan references a clay layer at 50 to 60 feet bgs twice on page 5 and once on <br /> page 7. It appears that the clay layer referenced on these pages is actually between <br /> approximately 40 to 50 feet bgs. If this is not the case, Nestle should so indicate in writing <br /> to Regional Water Board staff. <br /> 4) Nestle should identify parameters for base line groundwater or soil sampling that would be <br /> needed for various active, in situ remediation technologies with potential for use at the <br /> Former Facility. <br /> Nestle must complete the work proposed in the Work Plan and submit a report of findings with <br /> recommendations to the Regional Water Board on or before 2 July 2007. Please contact me at <br /> (916) 464-4675 or at Irownell cDwaterboards.ca.gov if you have any questions or concerns. <br /> James R. Brownell, P.G. <br /> Engineering Geologist <br /> Enclosure <br /> cc: Attached Distribution List <br />