The Snap Sampler--a passive/no-purge groundwater sampling system that saves money and improves data quality.
We've included pages of information, third-party studies, and a short video to help you understand why we consider the Snap Sampler to have the best balance of cost and data quality among active and passive groundwater samplers available today.
← Have a look at our short 3 minute video to show what Snap Sampling is all about
SNAP SAMPLER NEWS
February 12, 2013
Snap Sampler pneumatic trigger effective at 600 meters deep
Deep sampling can be difficult due to challenges associated with pumps—deep deployment and long operation time; or the use of potentially hazardous high pressure gas. The Snap Sampler with its pneumatic trigger system provides a solution by avoiding both problems. The Snap Sampler captures a sample downhole by “snapping” closed at the position you choose. The pneumatic trigger system requires only about 50psi of air pressure to Snap, regardless of how deep the samplers are submerged.
Very deep sampling made easy
Low pressure activation
Minimal equipment requirement
Sample from exactly where you want
A single air tube is used to lower and activate the Snap Sampler system. A check ball in the actuator allows water to rise in the air line, creating hydrostatic equilibrium with the water level. This means that air pressure to activate the trigger does not need to overcome submergence—only the activation pressure of the actuator itself. Theoretically, there is no depth limitation with the pneumatic Snap Sampling approach.
The Water Replenishment District of Southern California completed a test in late 2012 where Snap Samplers were deployed to nearly 2000 feet (600m) below ground surface, and nearly 1900 feet (570m) under water. Snap Samplers captured samples with this system at the precise depth deployed, with no doubt about where the water came from. A small 12v tire pump running for just a few seconds was all that was needed to “Snap” the Snap Samplers.
>Environmental Science & Technology paper published in 2010
Britt, Sanford L., Beth Parker, and John Cherry, 2010, Downhole Passive Sampling System to Avoid Bias and Error from Groundwater Sample Handling, Env. Sci. & Technol. volume and page information pending.
If you cannot access the full article, please "contact us" to request a copy of the paper
Parsons' 2005 McClellan Air Force Base Study: the Snap Sampler returned the best R2 correlations with low flow and volume purging of all the sampling methods tested.
Parsons described the Snap Sampler data as "...more consistently representative of the actual VOC concentrations in the well at the time of sample collection."
the "Comparison" pages include more detail on the study, and the Parsons report can be downloaded in its entirety
SNAP SAMPLING IS A "SNAP"
Why is passive, "no-purge" sampling with the Snap Sampler such a "Snap?"
Passive sampling relies on natural flow-through in the well and "passive" re-equilibration between the well and aquifer before collecting samples. No water is pumped from the well, so you don't need pumping equipment or heavy waste containers. Sampling takes ~15 minutes per well and you have virtually no logistics for equipment--you really don't even need a truck. That's why sampling with the Snap is a Snap.
The Snap Sampler takes "passive" a step further by sealing the sample in situ--eliminating the pour step at the well head. As a result, Snap Samples are truer to the condition of the sample while it is still in the well. You don't add artifacts from pouring under variable weather conditions, seasons, or the technique of the field sampler.
Is it OK to sample without purging?
Academic research, EPA, and ASTM guidance indicates flow-through in the well screen is normal and usual*. In most circumstances truly "stagnant" water is present only in blank well casing above the screen. The sceen interval inside the well normally contains free flowing formation water.
*ASTM, 2002, Standard Practice for Low-Flow Purging and Sampling and Devices Used fro Ground-Water Quality Investigations, ASTM designation D-6771-02.
*Powell and Puls, 1993, Passive Sampling of Groundwater Monitoring Wells Without Purging: Multilevel Well Chemistry and Tracer Disappearance. Journal of Contaminant Hydrology 12: 51-77.
*Puls and Barcelona, 1996, Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedures, USEPA Ground Water Issue Paper, EPA/540/S-95/504.
*Robin and Gillham, 1987, Field Evaluation of Well Purging Procedures, Ground Water Monitoring Review, v. 7, no. 4, p. 85-93.
The Interstate Technology and Regulatory Council (ITRC) has been providing guidance and information on passive technologies for several years. The ITRC diffusion samplers web site contains plentiful information on the efficacy of passive technologies. Numerous studies show that many passive methods are comparable to purge methods. So, yes, using the right techniques, you cansample effectively without purging.
Other pages on this web site illustrate the utility of the Snap Sampler, its cost-effectiveness, and how to contact us to conduct a trial at a specific site.
Cost comparison information is available, as well as information on new developments with the Snap Sampler, including large sample bottles and deep trigger systems.
Please take some time to learn from this website about available information and tools, such as the Site Data Comparisons, Frequently Asked Questions, downloadable Cost Calculator, downloadable Standard Operating Procedure, links to other sites of interest.
We hope this information is helpful, and thanks for coming by! We welcome feedback on the product and the site, please go to the "Contacts" page to send us a note or you can always call us at 585-385-0023 (8am-6pm Eastern-USA).
Now, a passive sampler that seals IN SITU... improving both data quality and field repeatability