SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

%WWI ..i MTM Ms. Donna Heran, REHS September 3, 1993 San Joaquin County Public Health Services Page 3 critical to an interpretation of groundwater impacts, WESTON displays analytical results estimated below the detection limits in the summary table and discusses their implications. Again, as a practical matter, this issue usually only becomes of interest when reviewing work relative to EPA Hazard Ranking System use which does not apply to this project. Monitoring for TPH-D. EDB and Total Lead Historically at this site, the hydrocarbon impact to groundwater has been defined primarily by concentrations of BTEX and TPH-G, with only minor concentrations of TPH-D, EDB and Total Lead observed. The EHD letter of February 17, 1993 stated that analyses for these constituents should continue for a minimum of two quarters. Based on this guidance from the EHD, WESTON advised in the Quarterly Groundwater Monitoring Report for the Second Quarter 1993 that due to very low or non-detectable levels of TPH-D, EDB and Total Lead, analyses for these constituents would not be conducted in future quarters. The only TPH-D concentrations found in the second quarter were 0.037 mg/L in MW-7 and 0.056 mg/L in MW-8. It was WESTON's opinion, based on experience with similar sites and the overall objectives of the groundwater monitoring program, that these TPH-D results were low enough to warrant discontinuation of TPH-D analyses in future quarters. Likewise, EDB was deleted from the analytical suite due to two consecutive quarters of very low or non- detectable results. WESTON believes that the objective of a groundwater monitoring program is to clearly define the limits of groundwater impact by including sufficient chemical analytical parameters for trend analysis. It is not a useful objective to analyze for all possible constituents at the lowest possible levels. For the ongoing monitoring at the San Joaquin project, this practical objective is well served by analyses for only BTEX and TPH-G, as shown by the results of the first two monitoring events which included analyses for all requested constituents. WESTON suggests that nothing would be gained by analyzing for additional parameters in the quarterly monitoring stage of the project and that in fact to do so, especially in the context of a publicly funded project, is a misallocation of public funds. In summary, WESTON recommends proceeding with the monitoring program as originally discussed, i.e., without future TPH-D, EDB and Total Lead analyses. Other Issues Finally, to assist in maintaining project continuity and scope, WESTON requests that EHD personnel refrain from directing WESTON field samplers to conduct activities which are outside the preestablished scope of work. Such action puts the field crews in a difficult position because all activities which are outside the scope of work need to be contractually approved by WESTON's client prior to implementation in the field. Should any such issues arise during EHD field oversight, WESTON management would welcome a call to discuss and resolve the SfK WgIER .WP