Passive Groundwater Sampling - Should I Make the Switch?

Most groundwater monitoring currently being conducted under various regulatory programs relies on some form of purging, or the removal of groundwater from a monitor well prior to sample collection. Within the past few years, however, passive groundwater sampling has evolved and continues to gain acceptance among regulators and industry as a reliable, cost saving, and environmentally friendly alternative sampling methodology. A change to a passive sampling program requires careful consideration, but it's a change worth evaluating in almost all groundwater monitoring applications.
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Ohio EPA to Publish Second Draft of Multi-Program Groundwater Monitoring Rules

In August 2006, Ohio EPA published draft Ground Water Rules that are intended to be codified under Ohio Administrative Code (OAC) 3745-506. Ohio EPA intends to replace the existing groundwater monitoring programs for individual landfill types (i.e., municipal, industrial, and construction & demolition debris [newly regulated]) and bring their monitoring programs together under one unified set of rules (multi-program groundwater rules). After four years of struggling through various iterations and numerous comments from the regulated community, Ohio EPA is set to once again issue draft rules. Click Here to read more.

EPA Extends Comment Period on Plan for Stricter PCE and TCE Drinking Water Limits

The Safe Drinking Water Act requires EPA to conduct a periodic review of existing National Primary Drinking Water Regulations and to determine which, if any, need to be revised. The purpose of the review, known as the Six-Year Review, is to identify those and limits requiring revision to improve or strengthen public health protection. EPA published its detailed review on March 29 2010 (75 FR 15500, March 29, 2010) and believes that four compounds are candidates for regulatory revision including acrylamide, epichlorohydrin, and the ubiquitous groundwater contaminants tetrachloroethene (PCE), and trichloroethene (TCE). The review suggest that stricter limits may be required for the compounds. Lowering of the MCLs for PCE and TCE would not only affect public drinking water supplies, but would require significant changes in groundwater monitoring programs and, in some cases, would push monitoring programs into corrective measures. EPA established a 60 day comment period for the March publication. This most recent extension, announced in a June 1 Federal Register notice, provides an additional 30 days (until July 1, 2010) to provide comments.

pH Probe Maintenance

Several of our clients perform some of their own routine groundwater sample collection or wastewater monitoring. Parameters such as pH, conductivity, and temperature, commonly are measured in the field. Proper pH probe maintenance ensures a faster response, more reliable measurements, and a longer life. A few tips to get the most out of your pH probe are provided below.

The pH probe should be cleaned regularly according to the manufacturer’s recommended procedure and at a frequency dependent on the fluid being measured. Clean probes with a mild detergent solution. When deposits are difficult to remove from a probe, a diluted hypochlorite solution may be used, but it is always best to learn manufacturer’s cleaning instructions. Different probes require different cleaning methods. Calibration should be performed after every cleaning.

Many probes are sealed and the reference solution can’t be replaced; however, some have a small opening near the top of the probe where fresh solution can be added - check with the manufacturer of the probe regarding correct solutions and filling procedures. The reference electrode chamber should consistently have the appropriate amount of reference solution and without air bubbles. Most manufacturers recommend that probes should not be wiped; this is to prevent transfer of static charge onto the glass bulb resulting in slow or drifting readings.

If the probe is used routinely, store the probe in a pH 4 solution or a storage solution (usually obtainable from the manufacturer). If the probe isn’t used for weeks at a time, dry storage is recommended; however, immerse the probe in a pH solution, allow sufficient wetting time, and calibrate before proceeding with measurements. Storing the probe in distilled water isn’t recommended (the filling solution will become diluted and probe response will be slow). With proper maintenance, a probe will have an average life of two years.