2007 Ground Water Summit

Monday, April 30, 2007 : 1:40 p.m.

Sampling Ground Water Using Vapor-Permeable Membrane Samplers

George Shaw and Jay W. Hodny, W.L. Gore & Associates Inc.

Long-term ground water monitoring programs can be costly in terms of field labor, waste disposal, and sample analysis.  . In addition, these programs must provide accurate data which meet data quality objectives.  No-purge, diffusion-based, passive ground water samplers offer an attractive alternative for ground water data collection, meeting stringent data quality objectives, while minimizing sampling and analytical costs significantly.  The growing acceptance of passive collectors for non-purge ground water sampling has led to the development of several diffusion-based sampling devices.  The earliest passive ground water sampling devices remain limited to detection in the volatile organic compound range.  The need to collect volatile, semi-volatile, and water-soluble organic compounds and metals, continues to drive research into finding improved passive samplers.  The body of published literature on the development, acceptance and efficacy of using passive, diffusion-based ground water samplers continues to grow.

 

One passive sampler is capable of reporting a broad spectrum of organic compounds.  The sampler is a sorbent-based, diffusion sampler constructed of waterproof, vapor permeable GORE-TEX® membrane.  The sampler’s performance was verified by the US EPA ETV program in 2002.  Compounds dissolved in ground water partition to vapor via the membrane, and diffuse and accumulate on the adsorbent housed within the sampler.  Field and laboratory research have demonstrated the sampler is effective in reporting volatile and semi-volatile organic compounds, including water soluble compounds.  Compound concentrations are calculated using measured sampler uptake rates and exposure times, corrected for individual well conditions.  The sampler is easy to deploy and retrieve, minimizing both field sampling costs and data variability.  The presentation will discuss the latest advances with the sampler, and will include comparisons to conventionally collected ground water.


The 2007 Ground Water Summit