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GeoInsighter Summer/Fall 2007 Newsletter NEW GROUND WATER RULE Return to the Newsletter Index On January 8, 2007, the United States Environmental Protection Agency (USEPA) passed the long awaited Ground Water Rule (GWR) Title 40 Code of Federal Regulations (CFR) Parts 141 and 142 aimed at evaluating and protecting sensitive ground water supplies from fecal and pathogenic contamination. Owners of surface water supplies, as well as ground water supplies under the direct influence of surface water, are familiar with the trials and tribulations associated with treating and disinfecting their supplies to provide protection from biological impacts and pathogenic diseases. The GWR, however, recognizes for the first time that ground water supplies not directly influenced by surface water, under certain conditions, can be vulnerable to biological impact. 
The USEPA estimates that approximately 114 million people in the United States consume ground water from public water supplies. Of this population, approximately 60 percent receive ground water that is either not disinfected or is not treated to adequate levels. In formulating the GWR, the USEPA cited studies by the Center for Disease Control that reported from 1991 to 2000 ground water systems were associated with 68 waterborne disease outbreaks that caused 10,926 illnesses. Depending on the sensitivity of the exposed population, impacts from bacterial and viral pathogens generally ranged from mild nausea and discomfort to the gastrointestinal tract to acute diseases such as Legionnaires Disease and meningitis. The rule preamble noted that, in extreme cases, death can result, citing an outbreak in New York where a healthy three year-old child died from kidney failure related to biological impacts in ground water. Typical sources of biological contamination can include improper storage or management of manure, runoff from land-applied manure, leaking sewer lines, and failed septic systems. In most geologic environments, biological contaminants are either too large to travel through subsurface media or are quickly bound onto fine-grained or organic materials. However, some specific geologic environments are susceptible to these impacts. Limestone areas can develop huge karst cavities (caves) that allow ground water to travel large distances without the benefit of soil filtering. Lava tube aquifers in volcanic terrain in western United States and in Hawaii can be similarly impacted. Very coarse gravel deposits do little to filter out biological contaminants. Aside from nitrates typically found in septic discharges, the major constituents at issue are bacteria and viruses. Bacteria are typically large in size when released into the subsurface and are quickly filtered out by most subsurface aquifer materials. Viruses are smaller and have the ability to travel farther in aquifers. The length of time that viruses can last in the environment is uncertain with estimates ranging from less than a few days to months and years. When a bacterium or virus is ingested in a human host, it will reproduce in the gastrointestinal tract regardless of clinical illness and can be reintroduced into the environment. To increase the safeguards against exposure to these impacts, the GWR sets up a risk-based strategy for monitoring, identifying, and remediating (treating). First, State regulators must conduct sanitary surveys every three years for community ground water systems with initial surveys due to be completed by December 31, 2012. Surveys must focus on all aspects of the system, including the distribution system, pumps, and storage locations. Many systems already rigorously monitor conditions in their distribution systems to maintain compliance with the Total Coliform Rule (TCR). The novel part of the surveys is the requirement in the GWR for the evaluation of the system's ground water source. States have some latitude in setting up these surveys and how results will be interpreted. The overall goal is to identify conditions that could cause increased risk of exposure to biological impacts. This effort could conceivably include identifying problematic threats such as septic systems or manure stockpiles within sanitary protective radii or hydrogeologic assessments that identify highly susceptible environments such as karst or very coarse gravel deposits. High risk systems, as identified during the surveys, could be required to conduct assessment monitoring of source water. Systems testing positive under the TCR provisions would also be required to conduct source water monitoring. Three test methods are currently allowable: Escherichia coli (E. coli), enterococci, or coliphage testing. E. coli and enterococci testing have been around for some time and procedures are simple and inexpensive. Coliphage testing provides a better probability of identifying impacts from human wastes, but because this test is newer, analytical costs are higher, and the results will initially be more difficult to interpret. Susceptible ground water systems that test positive for biological impacts will be required to treat to water quality criteria currently required for surface water systems. The potential impact of GWR implementation on ground water systems in New England is unclear. One study cited in the GWR preamble (Doherty 1998 ) was a survey of 124 supply wells in New England that included primarily unconfined and bedrock aquifers near potential sources or with documented nitrate or coliform detections. None of the wells selected for the study tested positive for E. coli or enteric viruses. This study suggested that the potential for biological impacts in New England aquifers is low in comparison to other parts of the nation. Similarly, a New Hampshire regulator reported that conditions at most ground water systems are well documented and frequently evaluated by regulatory staff; significant additional treatment and monitoring were not viewed as likely. Still, the surveys have yet to be conducted by the states, and the impact of the GWR on local ground water suppliers is not certain. Additional information regarding GWR can be found on the USEPA's website at http://www.epa.gov/safewater/disinfection/gwr/index.html. David A. Maclean, P.G., L.S.P., L.E.P. Return to the Newsletter
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