What’s in your toolbox? Part 2: Groundwater Sampling

Last month I discussed some of the common tools and equipment for soil sampling in a Phase Two Environmental Site Assessment. Many investigations will also require groundwater sampling, which will necessitate some additions and alterations to your sampling toolbox. Of course, you will still require the safety essentials, including a Site-Specific Health and Safety Plan, appropriate PPE and most importantly common sense.

Pre-Planning and Supplies

Similar to a typical soil sampling program, you will also need to pre-arrange a number of items for groundwater sampling

• Retain a qualified drilling contractor who is a licensed well contractor.
• Consult with your driller to confirm suitable methodology & equipment, well materials, protective well casings, well record data, etc. – there is a big difference in deep bedrock wells compared to shallow overburden wells.
• Field equipment – equipment and supplies for developing and sampling wells can include:

o    Waterra tubing, foot valves, bailers, in-line filters for metals sampling;

o    Peristaltic or bladder pump(s) and associated tubing, and power supply for pumps;

o    Flow cell or monitor to assess groundwater quality parameters;

o    Water Level meter with Interface Probe to measure water levels and check for free product.

• Drums, pails or totes for containment of purged water (plan ahead to minimize your work effort). It is also useful to have a few dedicated pails to collect groundwater for characterization during well purging (i.e. to measure specific well volumes and to confirm static conditions), prior to collecting samples for analyses.
• Lab-supplied sample containers and necessary preservatives, coolers, ice, etc.
• Check the weather and plan ahead – trying to sample groundwater wells in sub-zero temperatures can be difficult and challenging; when temperatures fall below -15C or so, it can become near impossible as pumps or batteries die and water lines freeze – not to mention frostbite.
• At the planning stage, unless we have existing site data, it can be difficult to accurately estimate the time needed for proper well development in order to achieve representative groundwater conditions. How many well volumes must be purged? How fast will the wells re-charge and equilibrate? How many site trips will this take? Allow sufficient time for your field work and prepare to be flexible in your program.

What’s in your groundwater sampling toolbox?

The preferred tools for groundwater sampling are based on experience (both good and bad). Some of the most common sampling tools, along with a few other helpful items are listed below:

• Decontamination supplies – generally not as complex as with soil sampling; but still will need buckets, brush, clean (distilled) water, lab-grade soap. I also have dedicated spray bottles with distilled water and isopropyl alcohol for small items.
• Ziploc sample bags (I prefer to double bag water samples, in the event of bottles breakage its less of a mess), indelible water proof markers, extra (waterproof) pens or pencils.
• Field book and pre-formatted monitoring well logs, and a scaled site plan for reference. Don’t forget to survey monitoring well locations for elevation at both ground surface and top of well pipe.
• Basic hand tools – make sure to include sockets/wrenches & special tools and keys to access different types of well covers, plus pliers, screwdrivers, a knife or tubing cutter etc. A stiff brush or broom and shovel are also useful to uncover slightly buried flush-mount well covers.
• Finding recently installed (or older) wells in winter can be difficult in winter conditions, and I have wasted many hours trying to find wells under a blanket of fresh snow and old ice. If you can’t install stick-up well casings (e.g., in a parking lot), consider placing thin wire stakes with flagging tape in the surrounding well seal – they won’t affect vehicle traffic or a snow plow, but they will assist in finding your wells, at least for a short time. Alternatively, you can place a magnet or large stainless-steel bolt within the well casing and use a metal detector to locate the buried well casing. Either way allow a bit of time to re-locate your wells in winter.
• I have a few off-beat items that come in handy: a plastic turkey baster to remove ponded surface water inflow from a well casing; wire coat hangers or specially bent steel tent pegs to fish out tubing that has fallen down the well (or a small ice fishing reel and large hook, if tubing is stuck further down the well), and some small hand clamps to hold sample tubing at set depths for sampling.
• I also bring a foam gardening pad – it’s much easier on my old knees than kneeling directly on gravel, ice, etc.

Strategic planning, and having commonly used items in stock can contribute to a more productive sampling program, and a more enjoyable field experience.

Bill Leedham, P. Geo., CESA
Bill is the Head Instructor and Course Developer for the Associated Environmental Site Assessors of Canada (www.aesac.ca); and the founder and President of Down 2 Earth Environmental Services Inc. You can contact Bill at info@down2earthenvironmental.ca