Though much of the article is true, in that Martinsville does have contaminated groundwater, there are inaccuracies and misunderstandings in the above-referenced article that I would like to clear up. I would like to reiterate that the primary health risks from the Pike and Mulberry plume are 1) potential vapor intrusion of the toxic chemicals PCE and TCE into homes and commercial establishments, and 2) the potential harm to health from drinking untreated private well water.
Carbon filtration of the City’s water has been ongoing since 2005. The EPA’s extensive 7 phased Remedial Investigation has determined that the vadose (top soil layer) is not expected to be a continuous source of contamination site wide (Page 7-1 Remedial Investigation found on EPA Pike and Mulberry website). The same report also stated that the plume is fairly stable with small variability in concentration (page 9-1). City water testing has consistently shown only one of three wells to be contaminated in the range of 20-30 parts per billion (ppb). Once the water is filtered and treated, all water consistently leaves the plant at non-detectable levels of PCE and TCE. Activated carbon life-span within the filters is averaging approximately 18 months, consistently, and has lasted as long as 26 months. These facts are in direct contradiction to the Edwards’ article, which states that “the contamination is increasing, requiring filters to be changed more frequently.” PCE levels were actually as high as 49 and 51 micrograms per liter as far back as 2009, so the levels do not appear to be increasing, nor are filter change frequencies increasing. No known continuous source exits that would cause aquifer PCE levels to rise. Bottom line, levels are and have been stable for quite some time, and future shifts in current concentrations are difficult to predict.
The City’s aquifer, which feeds the City well field, has a total of four toxic plumes. Three of the plumes had developed before the Pike and Mulberry streets plume, and were not a result of the Pike and Mulberry plume as the article implies (total of four plumes, not “four more plumes have developed”). One of the smaller plumes has, in fact, been treated and we are awaiting performance data assessment.
The article also states that “Martinsville Mayor Kenneth Costin, who took office in January, installed new carbon filters to stabilize the well water system.” This is not true; the filters have been in place since 2005. Mayor Costin does, however, assure the continued replacement of spent carbon for effective filtration, which assures the City water remains safe for consumption.
A misunderstanding within the article suggests the city is not meeting necessary safety standards, and that there are “two standards.” It states, “there is the public health standard, where the concentration is zero. Then there’s another standard, which is the industry and cost factor standard and that is what the city is in compliance with.” This implies one is health based and the other is not, and this is simply not true. Firstly, the zero-based standard referred to is called the “Maximum Contamination Limit Goal (MCLG).” This is not even a standard, nor is it enforceable; rather, it is a “Goal” as defined. Secondly, the other standard referred to, is the Maximum Concentration Limit (MCL).” The PCE MCL is the maximum allowable amount of PCE that can be present in tap water. The MCL is, in fact, a bona fide standard set by EPA in compliance with the Safe Drinking Water Act and is an enforceable standard. This is not simply an industry/technology and cost-based standard, but one which is derived based on three major considerations: 1) the available technologies and costs to remove contaminants, 2) the available analytical methods used to monitor for safe water accurately and consistently, but then 3) and most importantly, the MCL is derived with consideration to the potential health effects posed by a contaminant. The risks considered involve both cancer risk and non-cancer effects. To establish the MCL, EPA uses modeling based on both human and animal studies, and estimates err on the side of over-protection rather than inadequate protection.
The MCL for PCE is 5ppb (equivalent to five drops of water in an Olympic-size pool). It is estimated to pose a 3 in 10 million chance of cancer (Environmental Heath Perspectives-National Institute of Environmental Health Sciences). The PCE MCL standard is in no way comparable to a simple air purifier efficiency level (as suggested in the article), which is a mechanical performance level, not a safety limit which has health-based considerations. The MCL is the EPA enforceable safety standard that the City is in compliance with and in fact a standard the City consistently exceeds.
The article mentions the PlumeStop technology developed by Regenesis, which is being used by Wilcox to clean up the smaller O’Neal plume. The barriers are actually semi-permeable, allowing water to flow through and trapping PCE contaminant. The treatment also includes injection of bacteria that actually does the degradation (breakdown) of the toxic chemical to harmless substances.
As suggested correctly by the article, PlumeStop has application and could be a very useful addition to the current Proposed Plan released by the EPA. It could be used in a combination approach to the EPA plan. Specifically, it could be injected between the main plume and the well field, providing a safety barrier while larger treatment is applied to the more concentrated area. This approach is supported by the City and will be submitted during public comment. Community members are also highly encouraged by the EPA and City to read the proposed plan, the fact sheet, listen to the virtual presentation and submit your own comments. All the above can be found at www.epa.gov/superfund/pike-mulberry-pce. This site can be confusing. After going to the site, you will need to scroll down to “Continue reading announcements and key topics” and click. This will take you to the page with the virtual presentation.
To pull up the documents, Proposed Plan, Fact Sheet, Technical Memo on PlumeStop technology type media, the Feasibility Study and Remedial Investigation, instead of clicking on Continue reading announcements etc., scroll further down on the first page to “site documents and data” and click, from the next page click on WEB CONTENT-PIKE AND MULBERRY STREETS PCE PLUME. This will go to the table containing all the documents listed above.
In reference to EPA and IDEM ambient air testing, the article alluded to spots around town where “vapor intrusion is so bad, you’re breathing PCE as you’re walking down the street.” Most towns and cities all have small background levels of PCE in their outside air (ambient). The highest level of ambient air test results found by EPA (per the Remedial Investigation, Table 5-30) was 0.428 micrograms per cubic meter, which is approximately 0.06 parts per billion. Plus, PCE and TCE are very volatile, and once released into the atmosphere, do not remain long in any given area, but rather rise into the atmosphere, dissipate, and are eventually broken down.
Finally, I would like to point out one glaring error. The comment that, “As Martinsville moves toward remediation of the Pike and Mulberry plume, the EPA is lowering clean-up standards for PCE and TCE,” is simply not true. The “new draft risk evaluation of TCE” sited in the article, and said that “it didn’t find an unreasonable risk to the environment under any conditions of use, provided safety directions are followed,” is out of context and irrelevant to the Martinsville plume clean-up. This “risk evaluation” was a mandatory review as set forth by new changes and requirements to the Toxic Substances Control Act. The evaluations are to determine whether a chemical substance (existing or future uses), poses unreasonable risk to health or environment. The requirement (Risk Evaluations) gives EPA the tools necessary to ensure the safety of chemicals and significantly strengthen health protections for American families. It by no means weakens or lowers clean-up standards as the article suggests. The Maximum Contamination Limits for both PCE and TCE remain unchanged.
In closing, I acknowledge that most, if not all, inaccuracies were likely unintentional or a result of misunderstandings. I feel that all persons involved, to include the author, have the best of intentions and interests for Martinsville, in concert with EPA, to return its aquifer to a clean and safe state. We must continue to work together, remain transparent through effective communication and clear, accurate dissemination of information. Again, I highly encourage all concerned citizens to watch the EPA virtual presentation and submit your comments, as specified above.
Timothy K. Adams
DVM, MPH, PhD, MS