MEMO. July 1, To: Julie Moore, P.E. From: Kim Watson, RQAP GLP Amy Macrellis

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1 July 1, 2016 To: Julie Moore, P.E. From: Kim Watson, RQAP GLP Amy Macrellis MEMO Stone Project No Subject: Draft Summary of Toxic Scan Results At the February 18, 2016 Cabot stakeholder meeting, it was determined to be in all parties' interest to conduct the first Toxic Scan sampling and analysis required per Cabot s Indirect Discharge Permit (IDP) before the scheduled December 2016 sample date, and to split the sample between two labs as an added quality assurance measure. The two laboratories performing the analyses were Endyne Testing Laboratories in Williston, VT and TestAmerica in Buffalo, NY. Based on a comparison of the reported concentrations and review of the quality control data provided by both the laboratories, the data suggest excellent reproducibility between the two laboratories for detections greater than five times the reporting limit (Table 1). The Toxic Scan washwater sample was collected by James Bowes of Bowes Environmental, LLC on April 28, 2016, in accordance with the sampling procedure detailed in the Toxic Scan Sampling Work Plan dated March 23, For the TCLP volatile organic compound (VOC) analysis, a grab sample was collected from the first truck that was loaded as described in the March 23rd Proposed Toxic Scan Sampling Work Plan. Three 40 ml volatile organic analysis (VOA) vials for each lab were then filled from the first truck sampled to obtain the VOC sample. The VOC sample was limited to the first truck only since this represented the washwater subject to the least amount of possible mixing. This was also done to reduce potential VOC loss and to minimize cross contamination from other sources, such as truck exhaust. For the non volatile and semi volatile analytes, the washwater from each of the two disposal trucks was poured into a single 4,000 milliliter (ml) glass sample container in equal volumes of 667 ml measured by a graduated glass beaker. The split samples were generated from the 4,000 ml jar by pouring 2,000 ml into two 2.5 liter (L) glass jars, one for each lab. Following sample collection, and sample splitting, the capped VOA vials and the 2.5 L container were labeled and stored chilled on ice in a cooler, and delivered under chain of custody for transport to TestAmerica Laboratory in Buffalo, NY and Endyne Testing Laboratories in Williston, VT. The samples were specified for the TCLP preparation and analysis using SW846 Method 1311 followed

2 by analysis for VOAs by Method 8260C, for SVOAs by 8270D, for pesticides by Method 8081B and herbicides by Method 8151A. 2

3 Table 1. Comparison of Detected Analytes with Calculated Relative Percent Difference (RPD) Analyte TCLP Regulatory Level (if any) Units TESTAMERICA ENDYNE Relative Percent Result Reporting Reporting Result Difference Limit (RL) Limit (RL) (RPD) Metals Aluminum mg/l J < J < Barium 100 mg/l < J < Calcium mg/l 78.2 < < Chromium 5.0 mg/l < J < Copper mg/l 0.29 < <0.2 3 Iron mg/l 2.5 < < Lead 5.0 mg/l 0.02 < J Magnesium mg/l 8.5 < < Manganese mg/l < J < Nickel mg/l < J < Potassium mg/l 98.5 < < Selenium 1.0 mg/l J < J < Silver 5.0 mg/l J <0.006 <0.20 <0.20 NC Sodium mg/l 680 < < Zinc mg/l 0.44 B < < Volatile Organic Compounds Acetone mg/l 1.3 < < Chloroform 6.0 mg/l < < Unidentified Peaks None 1 Semivolatile Organic Compounds 3/4-Methylphenol 200 mg/l < < Unidentified Peaks >5 >10 Pesticides alpha-bhc mg/l J < <0.002 <0.002 NC beta-bhc mg/l J < <0.002 <0.002 NC Herbicides None Detected Notes: NR = not reported; NC = not calculated; J = value estimated, below laboratory reporting limit but above the limit of detection for the instrument and method 3

4 When the TCLP preparation and analysis is requested, the laboratory typically only reports results for the TCLP listed compounds; however, the laboratories were asked to report results for their full standard compound list for the methodologies for organic and inorganic compounds. A summary of the analytes detected by one or both of the laboratories is provided in Table 1. The table provides a list of the analytes that were detected, the TCLP regulatory threshold for those analytes (only for compounds included in the TCLP list), and results and reporting limits from each of the two laboratories. If an analyte was detected at concentrations below the laboratory s reporting limit but above the method detection limit for that laboratory and analyte, the result is reported as an estimate (estimated values are reported with J qualifiers following the result in Table 1). Neither of the two laboratories reported any analytical results that were higher than the TCLP regulatory levels (Table 1). There were very few analytes detected by either laboratory at concentrations above the reporting limits for any of the sampling protocols followed. Table 1 also includes the relative percent difference (RPD) for reported results from each laboratory. The RPD calculation is used to measure precision, meaning the reproducibility of individual measurements of the same property under a given set of conditions. For analytes where both labs reported not detected values, this does not provide any precision information; in these cases, precision should not be used to judge the data s validity. The lower the RPD value is, the closer to identical the two reported results are. When the RPD value for constituents in soil or sediment field samples are greater than 50%, greater than 30% for water samples, or greater than 100% for air, the precision or percent change of the sample results may suggest percent error in sampling or analysis. For multiphase sample matrices (solid/liquid) such as Cabot s washwater, RPD values of % may be observed. If duplicate samples return a RPD value greater than the acceptable range for analytes detected and the concentration of the analyte is at least 5X the method s detection limits, it suggests that there may be a problem with how the samples were collected and/or analyzed warranting further investigation into the cause for the poor reproducibility in the results. Analyte concentrations that are at or below their reported limits are expected to exhibit greater RPDs since values at or near the reporting limits are typically not as precise. The results compared well between the two laboratories with a two exceptions: 4

5 Results for 3/4 methylphenol (called m,p cresol in the TCLP list) exhibited a 99% RPD. For this type of sample matrix, however, results may vary by as much as 100%. The result for 3/4 methylphenol reported by Endyne was lower than that reported by TestAmerica ( mg/l from Endyne, and mg/l from TestAmerica, see Table 1). The high RPD value in this case may be due to the low ph of the sample. Percent recoveries of the acid surrogates in quality control samples run at the same time as these TCLP tests were lower in the sample from Endyne than from TestAmerica, but still within the acceptance criteria for the method. Results for Selenium exhibited a 150% RPD. The difference in the results is, in large part, a function of the low concentrations of selenium in the washwater, well below the reporting limit for both labs. As indicated by the J qualifiers, the reported values are estimates. Further, analyte concentrations that are at or below their reported limits are expected to exhibit greater RPDs since values at or near the reporting limits are typically not as precise, so the variability in these results is not considered unusual. 5