A new no-purge, non-displacement groundwater sampler
What Is It?
The HydraSleeve sampler is designed to collect representative water samples from monitoring wells without purging. The disposable sampler collects a discreet sample from only the 'fresh formation' water in the screened interval of the well. It is fast, inexpensive, simple to use, generates no purge water and collects a sample suitable for all analytical parameters.
Why It Works
The accepted protocol for sampling monitoring wells has required the removal of 3 to 5 times the volume of standing water in the well screen, casing and the surrounding filter pack prior to collecting a sample for analysis. This was done to assure that the fluid collected came from the formation and did not contain stagnant water from the non-perforated portion of the well. Using traditional sampling devices such as bailers or various pumping systems made this a time consuming (usually 1 to 2 hours per well) and costly process. If the well was contaminated, the water had to be containerized and disposed of in an acceptable manner. Disposal of groundwater that qualifies as a hazardous material can cost over $200 for a 55 gal drum. When multiple wells are sampled the costs quickly mount. Obviously, the less water that has to be removed prior to collecting a sample the better.
There has always been a strong interest in simplifying groundwater sampling by reducing the purge water and time required to complete a traditional sampling event. Over the past several years new methods and tools have been introduced to accomplish these objectives. Low flow sampling, passive diffusion sampling and, in special cases, no purge sampling using conventional bailers have been tested. These technologies are gradually being accepted as alternatives to the traditional purge and sample methods.
The underlying principal behind all of these new sampling methods is based on the premise that the screened interval is constantly in dynamic equilibrium with the aquifer. Numerous studies have shown that the flow of groundwater through the screen is mostly horizontal and laminar, with little or no mixing with the overlying water column. The HydraSleeve Sampler utilizes this principal to provide an inexpensive tool to sample monitoring wells for all parameters without generating purge water.