Van Walt Environmental Connect Issue Two

The Evolution of Groundwater Sampling

Groundwater sampling is nothing new. Alexander the Great, according to the Geological Society of London, is reported to have completed the earliest recorded ground water tracer test by using horse carcasses to demonstrate the course of an underground river in Asia. Around this time, approximately 320 BC, Aristotle taught his students that groundwater occurred in an intricate sponge-like system of underground openings and that water was discharged into springs from this underground system and that condensation of vapours in the system, together with minor amounts of infiltration of surface water, nourished the system. Wind forward to the beginning of the twentieth century and a horse-powered well machine could be hired for drilling wells at a cost of $1 per foot plus 10 cents for galvanized tin well casing. And the installation of a well could take 18 months or more and two hours just to hand draw the tools out of the hole! Fast forward to what we now consider the start of the environmental groundwater sampling business and compare to what happened earlier you may consider yourself lucky. Although methods in the very beginning, 30-40 years ago were crude, time-consuming, wasteful and difficult the industry had come a long way. Equipment like the Stevens Type F Water Level Recorder from 1969, a Keck Water Level Meter and Water Test Kit were available. Improvements in groundwater sampling are quite a bit less dramatic than improvements in mobile communication methods, but nonetheless they are substantial when viewed in an historical context. What has also developed significantly are the accepted groundwater methodologies used in the “The Snap Sampler was found to be relatively easy to use, especially with the improvements in design and construction as the demonstration progressed.” Louise Parker, Nathan Mulherin, Gordon Gooch, Tommie Hall, Constance Scott, Jay Clausen, William Major, Richard Willey, Thomas Imbrigiotta, Jacob Gibs, and Donald Gronstal of US Army Corps of Engineers®; Engineer Research & Development Centre “The Snap Sampler also provided lower sampling costs than low-flow sampling.” Louise Parker, Nathan Mulherin, Gordon Gooch, Tommie Hall, Constance Scott, Jay Clausen, William Major, Richard Willey, Thomas Imbrigiotta, Jacob Gibs, and Donald Gronstal of US Army Corps of Engineers®; Engineer Research & Development Centre What the experts say about The Snap Sampler & Other Passive Sampling Devices

collection of samples, the importance of monitoring extraction and compliance when it comes to contamination and water quality. As groundwater became more and more important as a vital resource that needs constant monitoring and in the early days of testing and monitoring, samples were often collected following the production of a full drum (or 2) of purge water waste. Sampling took hours and required the mobilisation of downhole pumps, power generators, voltage converters, multiple wastewater containers for every well, and staff numbers and brawn to move around all of that equipment. In the early days the accepted method of testing groundwater was to completely purge a well. Purging removed any silty material and deposits from the bottom of the well; stagnant oxidised water in the blank casing (blind section) and attracted groundwater from the aquifer!! The ‘classical Procedure’ of purging a well before sampling required 3 X wetted well volume of purged water. Now, with the advent of low flow sampling, this is very hard to imagine. With low flow sampling a pump is hung in the filter part of the well and adjusted to an extremely slow speed so reducing the need to renew (purge) the water in the blind section of the monitoring well. A further advantage of low flow sampling is the reduction in turbidity, significantly increasing the sample quality. Choosing the right sampling pump for your application will depend on the parameters you are measuring. For example a submersible impeller pump is good for most parameters including nitrates, EC and pH; whereas an air driven bladder pump might be more appropriate for VOCs. “ … the Snap Sampler ‘passes with flying colors’--with no statistical differences from the control.” Army Corps of Engineers. Louise Parker of US Army Corps of Engineers®; Engineer Research & Development Centre “The key advantage of passive samplers is the cost savings from reduced time for sampling and decreased waste generation. However, there can be other important advantages, including: 1) no pumps or power supplies are needed; 2) less on-site time is needed, reducing risks to personnel and inconvenience to site operations; and 3) reduction of data artifacts associated with purging (e.g., excessive drawdown, turbidity). Hans F. Stroo, Ph.D.; Stroo Consulting LLC; R. Hunter Anderson, Ph.D. Air Force Civil Engineer Center; Andrea Leeson, Ph.D. SERDP and ESTCP in Passive Sampling for Groundwater Monitoring: Technology Status Guidance, December 2014

“The Snap Sampler was able to collect adequate sample volume of for all of the analyses, including requirements for additional QA/QC samples.” Louise Parker, Nathan Mulherin, Gordon Gooch, Tommie Hall, Constance Scott, Jay Clausen, William Major, Richard Willey, Thomas Imbrigiotta, Jacob Gibs, and Donald Gronstal of US Army Corps of Engineers®; Engineer Research & Development Centre “Passive sampling technology is proving to be a reliable, robust and cost-effective tool that could be used in monitoring programmes across Europe. These devices are now being considered as a part of an emerging strategy for monitoring a range of priority and emerging pollutants.” NORMAN: Network of reference laboratories, research centres and related organisations for monitoring of emerging environmental substances In the 21st century a new method of sampling has evolved that eliminates all purge water waste – the passive sampling approach. Now, you can avoid nearly all equipment handling and time-consuming purge procedures. Is that possible? Skip right past low flow and go to no flow? In many cases, yes, passive sampling approaches allow you to sample groundwater monitoring wells without purging any

“Passive Sampling improves safety and field effort.” Louise Parker, Nathan Mulherin, Gordon Gooch, Tommie Hall, Constance Scott, Jay Clausen, William Major, Richard Willey, Thomas Imbrigiotta, Jacob Gibs, and Donald Gronstal of US Army Corps of Engineers®; Engineer Research & Development Centre “Passive, non-purge, ISS/Snap Sampling minimizes mobilization of particles and adds consistency to the sampling procedure. It also avoids handling and disposal of contaminated waters and the time and costs associated with pumping and field parameter measurements. “ Sanford L. Britt, Beth L Parker & John A Cherry of ProHydro Inc. and School of Engineering, University of Guelph, Guelph, Ontario, N1G 2W1 Canada. Paper: Environ. Sci. Technol. 2010, 44, 4917–4923 waste. This is accomplished by deploying a passive sampling device directly into the screen zone of the well and allowing equilibration with screen zone water. Over the last 10-15 years, extensive prove-out testing and statistical analyses have shown that passive devices deployed in the screen zone of monitoring wells in advance and left to equilibrate with ambient

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