EPA Holds Stakeholder Meeting on Perchlorate
EPA held a meeting and webinar on September 20 for stakeholders interested in EPA’s planned regulation of perchlorate. The focus of the meeting was on the analytical methods and treatment technologies. The agenda also included the state perspective, a consumer perspective, and a utility perspective.
In February 2011, EPA made a final decision to regulate perchlorate because EPA believes there is an opportunity to reduce the health risk by regulating perchlorate in drinking water. Based on the date of this determination, EPA will need to publish a proposed rule by February 2013 and they are in the process of developing the specific rule requirements and language now. Three states (MA, MI, NV) are participating in the EPA work group that is writing the proposed rule. This stakeholder meeting covered information that will go into the Health Risk Reduction and Cost Analysis that must be developed to support the rule.
EPA has been working to improve the analytical methods since perchlorate was included in UCMR1. The original ion chromatography method (EPA 314) has been refined a number of times to make it more effective for high TDS samples (314.1, 314.2). Additional methods utilizing Mass Spectrometry have been developed to lower the Method Reporting Level to less than 0.1 ug/L. The newer methods would make an MCL around 1 or 2 ug/L feasible, if the final MCLG drives the MCL to that low level.
The treatments being considered as possible Best Available Technology for perchlorate are anion exchange, biological treatment, reverse osmosis (RO), and RO in a Point of Use (POU) application. Ion exchange (IX) will provide good treatment, especially if a perchlorate selective resin is used. The effectiveness of treatment and operational cost will be dependent on the characteristics of the water being treated, especially the competing ions that could reduce the life of the media. Biological treatment is another option where perchlorate reducing bacteria in an anerobic environment break down the perchlorate. In addition to the fluidized bed or fixed bed reactors, this process also requires some pre and post treatment steps. RO provides very high percent removal for perchlorate but the treatment cost is likely to be high and the high volume residual stream may present disposal problems. EPA believes these treatment technologies will easily reduce perchlorate to around 4 ug/L and some are capable of reaching 2 ug/L. EPA is looking for data from water systems that have experience with any of these treatment processes.
Damon Guterman of MA DEP shared the state perspective. MA has had an MCL of 2 ug/L for perchlorate since 2006. After their initial round of monitoring, the state found 10 systems with perchlorate greater than 1.0 ug/L. Most were able to resolve their perchlorate issues without installing treatment (taking a well off line, etc.). Two systems added ion exchange treatment to their wells. Generally the state has not had any major challenges implementing their regulation. The Natural Resources Defense Council, speaking for consumers, encouraged EPA to move forward quickly and set a national standard for perchlorate. They pointed out that perchlorate is found in many parts of the country and that treatment with ion exchange can reduce it to less than 1 ug/L. The group is especially concerned about the consequences of perchlorate on young children, a life stage we all pass through. California has been at the leading edge of the perchlorate issue for many years. There are about 50 perchlorate treatment plants in the state and one of those systems brought the utility perspective. Ion exchange is the most commonly used treatment for drinking water. Anerobic biological treatment has been used in remedial clean up actions but not often for drinking water. The current CA standard is 6 ug/L. Utilities have concerns with the effect of a very low MCL on treatment options, driving utilities to higher cost treatment. Also, a very low MCL may require treatment of Colorado River water used extensively by large systems in the state.
This meeting did not address the health effects of perchlorate. The process for developing the Maximum Contaminant Level Goal (MCLG) is currently being considered by a special perchlorate panel of EPA’s Science Advisory Board (SAB). They have developed a draft report on the MCLG development process and will discuss that report in a teleconference on September 25. Details about the work of the SAB perchlorate panel, including the draft report, are available on the SAB website.
