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Mr. Ken Price . - 2 - • 31 July 2001 Program No. 96-817, and Geomatrix requests that they discontinue this data validation. Geomatrix states that it will continue to obtain duplicate samples, travel blanks and equipment blanks as usual. Board staff member Mr. Joseph Mello concurred with this request during a 10 March 2000 telephone discussion with Geomatrix staff. In the `Other Compounds' narrative portion of the monitoring reports, Geomatrix distinguishes between compounds that are detected at"trace"concentrations, which it defines as concentrations less than 10 times the practical quantitation limit (PQL), and compounds detected at concentrations greater than 10 times the PQL. Geomatrix presents the "trace" detections in a tabular form that readily calls attention to the compounds and the monitoring wells with which the compounds are associated, while the concentration values greater than"trace" are presented within a paragraph of text. Since the tabular format is an easy way to display and interpret pertinent data within a text portion of the report, it would be more useful if Geomatrix tabulated the concentrations of the detections exceeding 10 times the PQL and relegated presentation of the "trace" concentrations to the text. Geomatrix presents all analytical results in tabular format in the Appendix. Commencing with the November 2000 monitoring event, Geomatrix purged all the monitoring wells with dedicated low flow pumps (micro-purge), as was discussed with Mr. Mello in an 8 September 2000 telephone conversation. With the micro-purge technique, well purging prior to sampling consists of removing about three tubing volumes of well water until field parameters stabilize, as opposed to removing about three well casing volumes of water. Geomatrix reports in its Third Trimester 2000 Monitoring Report that the data obtained with micro-purge techniques appear comparable to previous data obtained with the higher purge volume techniques. However, Geomatrix does not present any direct comparison between the two techniques. Given the time variant nature of groundwater monitoring data, any discernable differences between the data obtained from the two sampling techniques will not become apparent until at least a year of sampling data is obtained and compared to previous years. Therefore, Geomatrix should incorporate a note onto the time concentration graphs that identifies when the sampling technique changed. Geomatrix presents time concentration plots for each monitoring well which display multiple constituents in an easily read format. The plots are arranged by monitoring well in numerical order. The plots would be even easier to interpret if they identify which aquifer the well is monitoring and if they were grouped by aquifer. In summary,please incorporate the following changes to the format of future monitoring reports: • Add a note to the time concentration graphs identifying when the sampling technique changed to micro-purging and which aquifer is represented by the graph. • Group the time concentration plots by aquifer. • In the `Other Compounds' textual portion of the report,tabulate detections that exceed 10 times the PQL. Pursuant to MRP No. 96-817, the next monitoring report is due 10 October 2001.