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Ms. Darcv O'Connor October 27, 1999 Paee 3 BMRI responded to the concerns voiced by the EPA field inspection team by placing pylon downgradient of the bog area. BMRI has not observed seepage flow at this location. In addition when other EPA personnel visited the site on a subsequent sampling event (July 21, 1999), EPA technician Ntr. Loys Parrish declined to sample this location when requestec. by Mr. Mike McGowan of the Costilla County Conservancy District due to the lack of flow. In the final paragraph of this section, statements aze made regarding the field protocol that was followed for sample handling, preservation, and chain-of-custody. According to the EPA inspection report, dissolved metals were analyzed in water that was first passed through a 4._° µm disposable filter membrane. At that membrane size, there should be no difference between dissolved and total concentrations. Based on the analytical results presented in the summary data table, the samples must have been filtered through a 0.45 µm membrane prior to analysis. Data Summary Table The data summary table presented in Attachment B offers a comparison between the "split" samples collected by Respondents during the EPA site visit. Note that the samples collected during the EPA inspection were not technically "split" samples because the samples were collected by successively filling a 1 liter cubitain~r and decanting into individual sample containers (including those provided by Respondents). Samples decanted by EPA personnel for Respondents were submitted for analysis to Sangre de Cristo Laboratory, Alamosa, Colorado and copies of the ori;;inal laboratory data sheets are included in Attachment B. EPA Field Samoline Techniques The following observations made by Respondents and its consultant were made during the field inspection by the EPA regazding the water quality sampling protocols followed by the EPA team: • The samples collected by the EPA represent duplicate samples as the method for filling sample containers was to successively fill a 1-liter cubitainer and dispettse into sample containers. The duplicate, in this case, is in contrast to a "split" wherein a lazge volume container (e.g., 5 gallons) would be filled and subsamples then taken ~iom the larger container. • Subsamples for analysis of dissolved constituents were obtained by field filtration using portable/disposable filtering devices and ahand-held vacuum pump. Containers for analysis of dissolved and total metals concentrations were acidified in the field using glass ampules of either nitric or sulfuric acid depending on the analyze(s). At RS-5 (the first sampling station), the containers to be acidified were placed on the top of a cooler with the lid off while the acid ampule was prepared. This break in sampling protocol would have allowed airborne dust from the nearby road to enter the sample containers. • Sample container caps were not sealed with pazaffm paper nor were sample containers stored in sepazate bags to prevent possible cross-contamination among samples from different locations. In addition, tamper-proof seals were also not applied to the sample bottles.