Lesson Learned Statement:*** The original LL was modified on 12/31/02. *** When developing an activity hazard analysis, all hazardous components indicated in the analytical data must be taken into consideration. Particular attention should be paid to hazardous material decomposition products as these compounds may be more hazardous than the original materials and be difficult to differentiate due to similar characteristics. Worker Personal Protection Equipment (PPE) must be readily available to provide protection for the worst possible hazard material or condition as identified in the hazard analysis.Discussion:Bechtel Jacobs Company (BJC) mobilized an in-situ treatability study for groundwater contaminated with trichloroethylene (TCE) as a dense non-aqueous phase liquid (DNAPL) at the Paducah Gaseous Diffusion Plant, Paducah Kentucky. The preliminary sampling results for concentration of TCE were evaluated and a PPE level was established for the project using data from a remedial investigation of the site. The PPE requirement during the remedial investigation at this site was modified Level D. As a precaution, personnel were equipped with photoionization detectors (PIDs) to measure and record peak and time weighted average readings for total volatile organic compound (VOCs) concentrations. The VOC of primary concern to the project in the planning stage was TCE. During the hazard evaluations and development of the Activity Hazard Assessment (AHA) for the project the focus was on measures to protect personnel from exposure to TCE.The project involved the drilling of 100-foot deep boreholes for the installation of electrodes and then backfilling the boreholes with electrode components and conductive fill. A borehole for the project had been drilled in an area of known high TCE contamination located near the suspected contamination source. Groundwater was present in the borehole as the electrode component installation commenced. A second tier subcontractor was positioned over the borehole in order to monitor the backfill progress when his PID alarmed. The worker immediately moved away from the borehole opening, shut down the equipment and proceeded quickly to the nearby health and safety support person to check the PID reading. The indicated level on the PID had already dropped below any action level but the peak level recorded by the PID exceeded the OSHA permissible exposure limit (PEL) peak value (300 ppm) for TCE. All other workers were evacuated from the job site and the work was suspended. Appropriate personnel were made aware of the exceedance and an occurrence notification report was generated. It is important to note here that all site personnel reacted in the correct manner in response to the alarming PID. Bioassay samples were collected from the potentially exposed workers as a consequence of the potential exposure. Analyses of these samples were negative for TCE exposure. Two days later, the subcontractor performed sampling of the atmosphere in the borehole at 50 feet below ground surface by two separate methods (Drager tubes and Summa canisters) for analysis of 46 compounds with the primary constituent known to be TCE. The laboratory that conducted the analysis of the atmosphere samples had to perform the analysis a second time using a higher dilution factor due to the TCE levels in the samples. The laboratory reported the TCE level but indicated that all other compounds were below detection levels. Based on this data, work resumed on the electrode installation in Level C PPE using additional protective measures including powered air purifying respiratory protection, an infrared analyzer to monitor the breathing zone, and additional engineering controls. During the course of the resumed work the engineering control on the auger was removed in order to remove the auger from the borehole. Upon the removal of the auger, the infrared analyzer alarmed for VOCs including vinyl chloride. Personnel confirmed with the manufacturer that the infrared analyzer could detect vinyl chloride however, results were not valid due to interference caused by high concentrations of TCE. Again, all project personnel evacuated the work site in the correct manner as a response to the alarming monitor. Project and Sample Management personnel reviewed the laboratory results and noted that at the reported dilution level only TCE was measurable with all other compounds reported as not detected. Management contacted the laboratory that performed the analysis to inquire about any data that might exist from the first analysis attempted with the standard dilution factor. The data indicated the presence of vinyl chloride approximately 50 feet below ground surface at a detectable level and varying amounts of other trace compounds marked as "estimated" due to interference from the high levels of TCE in the samples. Vinyl chloride, an extremely volatile decomposition product of TCE, has a much lower PEL than TCE. The project determined that workers would use Level B PPE and supplied air because air purifying respirators are not certified for vinyl chloride protection. A Vinyl Chloride Monitoring Plan was approved and implemented and the AHA was revised to address the identified respiratory hazards. No Vinyl Chloride was found in the breathing zone during the vinyl chloride monitoring event. PPE was reduced to Level C at the end of the Vinyl Chloride Monitoring Event. Analysis:The subcontractor based the characterization of hazardous constituents on a previously conducted remedial investigation of the site. TCE in high concentrations was known to be at the site and this contaminant was closely monitored. The concentration of all other constituents including Vinyl Chloride were measured at levels well below any regulatory and health limits and were not considered to be contaminants of concern for worker protection. In retrospect, the remedial investigation did not fully characterize all hazardous components within the contamination work area and therefore the Project did not develop all appropriate protective controls. Planning and preparation for potential level B PPE was not provided. Constituents, such as vinyl chloride, presented potential hazards to personnel due to the differences in exposure limits and those hazards were not addressed in the development of the AHAs because there was no indication from the remedial investigation that the constituents existed at potentially hazardous levels.Recommended Actions:Involve Subject Matter Experts (SMEs) in the analysis of all potential hazardous material, including degradation constituents, to ensure appropriate levels of hazard control and PPE are implemented. Any equipment or vapor detection devices should be evaluated and the vendor/manufacturer claims for performance accuracy independently verified before the equipment or detection device is utilized as a hazard control. Projects should always be aware of changing conditions and evaluate any new hazards that are identified during the performance of the task.When planning for excavations in chemically or radiologically contaminated areas, the potential for the presence of hazardous constituents and/or chemical decomposition by-products should be evaluated during the Activity Hazard Review (AHR) and Activity Hazard Analysis (AHA) development phase. Data from on-site monitoring instruments and analytical sample data should be carefully evaluated and conservatively interpreted to maximize personnel safety. Anticipate and prepare for the worst probable conditions when selecting PPE for a job. Always consider the potential for decomposition of any hazardous materials present since some of those products are often more hazardous than the original materials. Originator:BJC Paducah Site Environmental Projects, John Farrell (270) 441-5261; Assisted by: Jennie Henson, PWT, (270) 441-5192Validator:Larry Young, BJC Paducah Site (GWOU) Senior Hydrogeologist, (270) 441-5187; Mark Gage, BJC Paducah Site GWOU Lead Engineer, (270) 441-5125Contact:Joanne E. Schutt, (865) 483-0554, ext 103Name Of Authorized Derivative Classifier:Montgomery R. Breneman, (270) 441-5175Name Of Reviewing Official:Montgomery R. Breneman, (270) 441-5175Priority Descriptor:Yellow / CautionKeywords:Groundwater treatment, trichloroethylene (TCE), vinyl chloride, volatile organic compounds (VOC), personnel protective equipment (PPE), photoionization detectors (PIDs), treatment wellsReferences:Occurrence Report: ORO-BJC-PGDPENVRES-2002-0016Information in this report is accurate to the best of our knowledge. As means of measuring the effectiveness of this report please use the "Comment" link at the bottom of this page notify the Lessons Learned Web Site Administrator of any action taken as a result of this report or of any technical inaccuracies you find. Your feedback is important and appreciated. DOE Function / Work Categories:Environmental RestorationMaterial - Material Handling Well Drilling Waste Management ISM Category:Analyze HazardsDevelop / Implement Controls Hazard:Personal Injury / Exposure - Hazardous Material (General)
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