From 2002 to 2014, while under contract with another engineering firm, Truesdail supported PG&E’s Hinkley and Topock facilities by providing courier service, laboratory analytical services, Level IV reporting, and electronic data deliverables. This included the analyses of Hexavalent Chromium with low level reporting limits (0.200 ppb). During the duration of the contract, Truesdail adhered to the strict protocols set forth in the Site Quality Assurance Protection Plans and Truesdail is very familiar with the program and sampling locations.
At the beginning of every quarter, Truesdail would prepare the pre-preserved sample containers with labels identifying the preservative as well as any QC samples. All sample containers were pre-cleaned and certified to EPA standards. The containers would then be delivered by Truesdail staff to the field office at the Hinkley site and at the Compressor Station at Topock.
Once notified of the sampling schedule, Truesdail would schedule a member of their Field Services department. If any delays were to be expected due to unforeseen circumstances (road conditions, vehicle issues, etc.), Truesdail would immediately notify the field contact at the sites. Upon arrival, the samples would be checked against the Chain of Custody (COC) documentation prior to signing. This would insure that Truesdail would not leave the site until all samples were accounted for. The samples would then be transported to Truesdail’s ELAP-Certified laboratory.
Upon arrival at the laboratory, Truesdail Log-In staff would then unload the samples from the coolers. The samples would be checked versus the COC and Truesdail would sign the samples into their custody. Samples would be checked for temperature, condition, and appropriate preservatives (if applicable) and the results and observations would be noted on the COC and on the Sample Receipt Checklist. Additionally, with the exception of VOC samples, pH would be taken using litmus paper. VOC samples would have their pH taken when being open for analysis. Any anomalies would be noted in the laboratory records and reported in the Case Narrative section of the final report. The COCs would be provided electronically to the client within 48 hours of sample receipt.
After inspection and records notations, all sample information would be entered into the tracking system (LIMS), and unique analytical sample IDs were assigned. The information was promptly reviewed by the designated Project Manager as soon as possible for accuracy. A strict internal chain of custody policy was followed. Project samples were stored in a secure, restricted access area when not in use and samples were checked out and checked back in by the analysts who used them. Internal custody records were maintained as part of the documentation file for each sample.
Any specific instructions concerning the analysis specified for each sample was communicated to the analysts by the Project Manager. Analytical batches were created, and laboratory QC samples was introduced into each batch. While in the laboratory; samples were stored in controlled-access, temperature-applicable areas. Refrigerators, coolers, and freezers were monitored daily for temperature. The acceptance criterion for the temperatures of the refrigerators and coolers was 4°C ±2°C and the acceptance criterion for the freezers were between -7°C and -20°C. All of the cold-storage areas were monitored by using thermometers calibrated with a National Institute of Standards and Technology approved traceable thermometer. Records including acceptance criteria were maintained. Samples for volatile organics analysis were stored separately from other samples, standards, and sample extracts. Samples were stored after analysis until disposed of in accordance with applicable local, state, and federal regulations and disposal records were maintained by the laboratory.
Prior to sample analysis, laboratory instruments were calibrated by qualified personnel prior according to the procedures specified for each method. Calibration was verified at method-specified intervals throughout the analysis sequence. The frequency and acceptance criteria for calibration was based on those requirements set forth in the program QAPP. Calibration requirements included initial calibration of all instruments. Initial calibrations were re-established if the last calibration was established more than 1 year prior to the start of a sample’s analysis for gas chromatography, gas chromatography-mass spectrometry, daily for inductively coupled plasma, and inductively coupled plasma-mass spectrometry (ICPMS) per method SW 6020A and SW 6010C, the last calibration was established more than 4 weeks prior to the start of a sample’s analysis for hexavalent chromium by ion chromatography, two consecutive continuing calibration standards failed, or if the operating conditions changed. The calibration techniques used were those defined in the QAPP.
Continuing calibration verification analyses was performed to ensure that the instruments were not being adversely affected by the sample matrix or other instrument failures that would increase or decrease the sensitivity or accuracy of the method. Truesdail performed continuing calibration for all methods in accordance with the specific requirements in the method and laboratory SOP. All analytes were required to meet the continuing calibration as defined in the QAPP.
Following the specific requirements in the QAPP, laboratory QC checks were performed to indicate the state of control that prevailed at the time of sample analysis. The QAPP specified requirements for method blanks, LCSs, surrogate spikes, and MS/MSD.
Method blanks were used to monitor each preparation or analytical batch for interference or contamination from glassware, reagents, and other potential contaminant sources in the laboratory. The method blanks were an analyte-free matrix (laboratory reagent water for aqueous samples or Ottawa sand for soil samples) to which all reagents are added in the same amount or proportions as are added to samples. It was processed through the entire sample preparation and analytical procedures along with the samples in the batch. There was at least one method blank per preparation or analytical batch. If a target analyte was found at a concentration that exceeds ½ the RL (except method EPA 218.6 – where the MB is not to exceed 0.02 μg/L), corrective action was performed to identify and eliminate the contamination source. Associated samples were re-prepared or reanalyzed, or both, after the contamination source has been eliminated if the compounds detected in the associated blank are also present in the field samples.
Laboratory Control Samples (LCS) consisted of an analyte-free matrix (laboratory reagent water for aqueous samples and Ottawa sand or glass beads for soil samples) spiked with known amounts of analytes that came from a source different than that used for calibration standards. A complete target analyte list for each method that was specified in the QAPP was spiked into the LCS. The spike levels were less than or equal to the midpoint of the calibration range. If LCS results were outside the specified control limits, corrective action were taken, including sample re-preparation or reanalysis, or both, if appropriate. Any repreparation or reanalysis, or both, was documented and provided in the analytical report. If more than one LCS was analyzed in a preparation or analytical batch, the results for each of the LCSs analyzed were reported.
Surrogates were spiked into the standards, the samples, and QC samples prior to sample preparation. Surrogate recoveries were used as an indicator of accuracy, method performance, and extraction efficiency. If surrogate recoveries were outside the specified control limits, corrective action was taken, including sample re-preparation or reanalysis, or both, if appropriate. Documentation of the re-preparation or reanalysis, or both, was provided in the analytical report.
Matrix spike / matrix spike duplicates of target analytes were spiked into the samples and recoveries were used to evaluate the effect of the sample matrix on the recovery of the analytes of interest. One MS/MSD (MSD where appropriate) per 20 project-specific samples was analyzed for the target analyte list for each method specified in the QAPP with the exception of PCBs. The spike levels were less than or equal to the midpoint of the calibration range and any exceedances of control limits were flagged in the analytical report.
The program called for special protocols in regards to the Matrix Spike for Hexavalent Chromium. This is a result of interference from groundwater upon the sensitivity of Method EPA 218.6. The special protocols are described below.
Non-detect sample results were analyzed by Truesdail by spiking the samples with 1 μg/L of hexavalent chromium to ensure that identification was accurate and verified that false negatives were detected. For samples with detected results, the laboratory analyzed an MS by spiking the sample with hexavalent chromium at a level not less than 25 percent of the sample concentration. Truesdail followed the standard protocol of 1 MS and 1 laboratory sample duplicate per 20 samples, unless otherwise directed. If the MS was not recovered or the peak was outside of the established retention time window for either detected or nondetect results, the laboratory made a fivefold dilution of two aliquots of the sample. The first aliquot was analyzed without the spike; the second aliquot was spiked with hexavalent chromium at a concentration consistent with the concentrations previously listed and the recovery and peak retention times evaluated. If this MS recovery was not within laboratory QC limits or the peak was not within the laboratory retention time window, the laboratory diluted two additional aliquots of the sample tenfold, spike one of the aliquots, and analyze the sample/MS. This procedure was then performed at successively greater dilutions of 25:1, 50:1, or 100:1 until the peak identified in the post spike analysis was within the established retention time window for hexavalent chromium and the recovery of the spike was within the laboratory QC limits listed in the QAPP. The detected result that was reported by the laboratory on the final data package was chosen from the dilution where both the peak detected in the unspiked and the spiked sample were within the appropriate retention time and the MS was recovered within the QC control limits. The RLs were raised to the level of the appropriate dilution. For nondetect results, the dilution selected by the laboratory for reporting was taken from the smallest dilution that yielded an MS recovery within QC control limits and was within the appropriate retention time window.
The laboratory confirmed the preservation of Cr(VI) samples at the time of sample receipt. Truesdail used NaOH one drop at a time to make any adjustments that were needed to bring the sample pH into the appropriate pH range of 9.3 – 9.7. Prior to using the NaOH, the laboratory checked the NaOH by adding 10 drops to 250 ml of DI water and analyzing for Cr(VI) using the modified EPA method 218.6 for low level Cr(VI) and verify there was no detectable Cr(VI) in the NaOH (ND at 0.06 μg/L). Samples from the sites also had a special analytical approach for dissolved chromium and hexavalent chromium. The steps taken are described below.
If the Cr(VI) result was less than 4ppb and Cr(VI) result differed from the dissolved Cr result by more than 0.7 ppb, the laboratory contacted the program chemist and reanalyzed the sample for dissolved chromium. If the Cr(VI) result was greater than 4 ppb and Cr(VI) result differed from the dissolved Cr result by more than 20 percent relative percent difference, the laboratory contacted the program chemist and re-analyzed the sample for dissolved chromium. For each sample in the Domestic program a Cr(VI) matrix spike (MS) was analyzed using the Matrix Spike and Dilution Protocol outlined above. In addition, any sample requiring the re-analysis of dissolved chromium also had a Cr(VI) matrix spike (MS) analyzed using the Matrix Spike and Dilution Protocol. If the Cr(VI) result was greater than the dissolved Cr by more than 20% the laboratory contacted the program chemist and re-analyzed the sample. Samples that have a non-detected hexavalent chromium result at 0.2ug/L by the “normal” EPA 218.6 method for the DOM and GWM project samples were reanalyzed by the modified EPA 218.6 for low-level hexavalent chromium.
Some methods required the use of internal standards to compensate for losses during injection or purging or losses due to viscosity. For those methods, a measured amount of the internal standard was added to the standards, the samples, and QC samples following preparation. In the internal standard results exceeded the control limits, corrective action were taken, including sample reanalysis, if appropriate and any corrective action was documented in the analytical report.
Certain methods required a laboratory duplicate be performed instead of a matrix spike duplicate. A laboratory sample duplicate was a sample duplicate selected by the laboratory and subjected to the same preparation and analytical procedures as the native sample. The RPD between the results of the native sample and laboratory sample duplicate measured the precision of sample results. The data collected also yielded information regarding whether the sample matrix is homogenous or heterogeneous.
Interference check samples were used in inductively coupled plasma (ICP) analyses to verify background and interelement correction factors. They consisted of two solutions with Solution A containing the interfering analytes, and Solution AB containing the analytes of interest and the interfering analytes. Both solutions were analyzed at the beginning and at the end of each analytical sequence. When the interference check sample results exceeded the control limits, corrective action were taken, including sample reanalysis, if appropriate.
Retention time windows for gas and liquid chromatographic analyses were established by replicate injections of the calibration standard over multiple days as described in SW846 8000B, analytical method, or appropriate laboratory SOP. The absolute retention time of the calibration verification standard at the start of each analytical sequence was the centerline of the window. For an analyte to have been reported as positive, its elution time must have been within the retention time window.
Every effort was made to ensure the holding time requirements specified in the QAPP were met. This included split shifts or having log-in technicians and analysts working non-traditional work hours and/or weekends. For methods requiring both sample preparation and analysis, the preparation holding time was calculated from the time of sampling to the completion of preparation. The analysis holding time was calculated from the time of completion of preparation to the time of completion of the analysis, including required dilutions, confirmation analysis, and reanalysis. For methods requiring analysis only, the holding time was calculated from the time of sampling to completion of the analysis, including required dilutions, confirmation analysis, and reanalysis.
Confirmation analysis was also performed as specified for specific organic methods when the result was at or above the RL. Both the primary and confirmation results were reported. Unless one of the analysis was specifically designated as the confirmation by the method, the more concentrated result was reported as the sample result and the lesser concentration result as the confirmation. All calibration and QC requirements met when confirmation analysis was performed.
To maintain the lowest possible RLs, appropriate cleanup procedures were employed when it was indicated by the method to remove or minimize matrix interference. Methods for sample cleanup included, but weren’t limited to, gel permeation chromatography, silica gel, alumna, florisil, mercury (sulfur removal), sulfuric acid, and acid/ base partitioning. Method blanks, MS/MSDs, and LCSs were subjected to the same cleanup procedures performed on the samples to monitor the efficiencies of these procedures.
Truesdail is aware of the importance to minimize dilutions and strives to maintain the lowest possible RLs. When dilutions do become necessary because of high concentrations of target analytes, lesser dilutions are also reported to fully characterize the sample for each analyte. The level of the lesser dilution is such that it will provide the lowest possible RLs without having a lasting deleterious effect on the analytical instrumentation.
When any sample exhibited characteristics of matrix interference that were identified through analytical measurement or visual observation, appropriate cleanup procedures as specified in the QAPP were implemented. Any analyses conducted at a dilution where all analytes were reported as non-detect above the QAPP RL were discussed with the project chemist prior to finalizing the report.
Standard materials were of known high purity and traceable to an approved source. Pure standards did not exceed the manufacturer’s expiration date or 1 year after receipt if no expiration date was provided. Solutions prepared by the laboratory from the pure standards were used within the expiration date specified in the laboratory’s SOP. All other supplies and consumables were inspected prior to use to ensure that the supplies met the requirements specified in the appropriate SOP. The laboratory’s inventory and storage system ensure their use within the manufacturer’s expiration date and storage under proper conditions.
Truesdail analyzed a double blind sample for all project parameters at no less than at least once a year. For methods where multiple analysts perform the analyses, each analyst would analyze at least one sample per year.
After analyses was completed, all data underwent a minimum of three levels of review at the laboratory prior to release. The analyst performing the tests initially reviewed 100 percent of the data. After the analyst’s review has been completed, 100 percent of the data was reviewed independently by a senior analyst or by the section supervisor for accuracy, completeness and compliance with calibration, QC requirements, and holding times. Analyte identification and quantitation was verified. Calibration and QC results was compared with the applicable control limits. RLs were reviewed to make sure they met the project objectives. Results of multiple dilutions were reviewed for consistency. Any discrepancies were resolved and corrected. Laboratory qualifiers were applied when there were nonconformances that had the potential to affect data usability. These qualifiers were properly defined as part of the deliverables. All issues that were relevant to the quality of the data were addressed in the case narrative. The laboratory QC manager reviewed a minimum of 10 percent of data or deliverables generated for the Program against the project-specific requirements. A final data review was conducted by the laboratory manager or technical director to ensure that all required analyses were performed and that all documentation was complete.
It was the Project Manager’s responsibility to compile, generate, review, and submit Level IV reports as defined in the QAPP. Both a hardcopy report and an electronic copy were provided. The Level IV Reports included the following: