Aggressive Fluid Vapor Recovery (AFVR) is a cost effective means of applying dual phase extraction (DPE) for the purposes of quickly removing hydrocarbons from contaminated monitoring wells. This process calls for the use of a vacuum truck or trailer mounted vacuum system with an accompanying tank for collection and storage of the extracted materials (Also see: Mobile Multi Phase Extraction (MMPE) or Aggressive Fluid Vapor Recovery (AFVR) mobile dual phase extraction trailers).
When performing this scope of work the environmental professional relies on several scientific parameters to determine the effectiveness of the recovery process over the course of the testing period.
Vacuum flow rates, relative humidity and temperature readings are collected by the use of monitors like the Testo 445. The Testo 445 offers monitoring for all three of the aforementioned parameters as well as the ability to data log and recall MIN/MAX/MEAN of a given sample taken.
The use of vacuum gauges like Dwyer's Magnehelic Gauge help to determine changes in vacuum levels in the wells being used during the extraction and surrounding monitoring wells for influence. Sometimes pressure transducers like In-Situ's MiniTROLL or LevelTROLL 700 are deployed into surrounding wells to log for changes of the groundwater table during testing.
When determining concentrations of the hydrocarbons removed, consultants use handheld organic vapor analyzers (OVAs) like the Bacharach TLV Sniffer, Thermo TVA-1000, and RAE Systems MiniRAE 3000. Please note, if you do not have a local source for ultra-high purity hydrogen, then we do not recommend using the Thermo TVA-1000 since the instrument's flame requires it. If you anticipate levels in excess of 15,000 ppm, either the Bacharach TLV Sniffer or Thermo TVA-1000 are the best options. For low to mid VOC concentrations (0-15,000ppm), any of the mentioned OVAs would be sufficient.
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