SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Mr. Mike Desso • 3 _ • Nestle USA Inc. 19 November 2007 sand within the targeted sand interval. The Work Plan proposes aquifer testing by performing pumping tests on the newly installed groundwater extraction wells. Following aquifer testing, remediation system modifications will be made; the existing extraction wells EW-1 and EI-1 will be taken offline and the new wells placed online. A startup and prove-out sampling schedule is proposed for the first month of system operation; influent, intermediate, and effluent discharge samples will be collected daily for the first week and weekly for the remainder of the month; after the first month, the Work Plan proposes monthly influent and bimonthly intermediate and effluent sampling of the system discharge. Work Plan Comments 1. Nestle did not propose to place an extraction well in the upper sand layer that has concentrations of TCE up to 2,500 pg/L, apparently because the extent and concentration of TCE is considerably smaller than the extent in the lower contaminated sand layer. Also, Nestle assumes that pumping in the lower sand layer will control TCE migration in the upper layer. To evaluate this assumption during the pumping tests of the two new extraction wells, Nestle must monitor the piezometric head in monitoring well M-1 B, which is screened in the upper sand within the TCE contaminated area. If the results of test analyses do not support the assumption, Nestle must incorporate pumping of the upper sand layer into the pump and treat system modifications. 2. The frequency of groundwater sampling from monitoring wells M-1 A and M-1 B must be changed from annually to quarterly beginning with the next scheduled quarterly event at the Former Facility. 3. Nestle proposes to collect semi-annual groundwater samples from the four monitoring wells for laboratory chemical analyses. However, as required on page 3 of Monitoring and Reporting Program No. R5-2005-0829 (MRP), Nestle must collect and analyze samples from new monitoring wells on a quarterly schedule. Also, the new monitoring wells must be monitored, and sampled according to the requirements of Tables 3 and 4 of the MRP. 4. Nestle must begin to monitor and sample the two new groundwater extraction wells immediately after installation and development, in accordance with Table 3 of the MRP. 5. Following installation and development of the four groundwater monitoring wells and two extraction wells, and performance of the aquifer testing and test data analysis, Nestle must submit a report documenting installation and testing activities. In addition, the report must identify any changes to the groundwater extraction system proposed in the Work Plan, if necessary. The report must be submitted to the Regional Water Board on or before 4 February 2008. 6. Following completion of the first month of treatment system monitoring, Nestle must submit a report documenting the system installation, startup, and prove-out results. The report is due on or before 3 March 2008. After completion of the first month of system monitoring, Nestle must monitor and sample the system in accordance with Tables 1 and 3 of the MRP.