Providing a safe and reliable water supply is one of the most important functions that New Brighton performs. New Brighton successfully dealt with the Army’s contamination of its water supply in the 1980s. In 2014, the City and the Army reached a landmark settlement that secures funding for our state-of-the-art water treatment plant, which is designed to remove known Army contaminants. The City now has taken further steps to address a newly-identified contaminant.
Scientific and technological advances have resulted in better methods for detecting contaminants at extremely low concentrations. Using this technology, testing by the Minnesota Department of Health (MDH), and independently verified by the City, has detected trace amounts of 1,4-dioxane (dioxane) in the City’s water. Dioxane is an additive found in solvents that were used at the Twin Cities Army Ammunition Plant.
No regulatory limit on the amount of dioxane permitted in drinking water has yet been set under the Federal Safe Drinking Water Act. The MDH, however, has set an advisory limit of 1 part per billion (ppb). The recent testing conducted by MDH and the City has detected dioxane at levels ranging from 2.9 ppb to 5.5 ppb. This newly-identified contaminant is not unique to New Brighton; it has been found in states across the country, including Arizona, New York, Kansas, New Hampshire, Indiana, Michigan, Massachusetts, and Wisconsin.
Although the health risk is very low, and there are no enforceable state or federal dioxane regulations, the City takes any risk seriously. The City has already taken steps to remove the risk by using wells in a deeper aquifer that have been confirmed to be dioxane-free. The City will continue to use these dioxane-free wells until a proven treatment technology, funded by the Army, is in place to remove dioxane from wells where it has been detected. The Army has stated that it is committed to working cooperatively with the City to develop this response.
The New Brighton water system has undergone major changes since the discovery of volatile organic compounds (VOCs) in the City water wells in July of 1981. Trichloroethylene (TCE), a common degreasing solvent and suspected carcinogen, was found in the wells at levels ranging from a few parts per billion to over two hundred parts per billion. The well water also contained lesser quantities of trichloroethane, dichloroethane, and dichloroethylene. The City immediately responded by changing the order of usage of the wells to use the lowest contaminated wells first. In addition, an odd/even lawn sprinkling procedure was put into effect to control water demand.
At the time of the discovery of the contamination the City’s water supply consisted of eight wells, Well #2 through Well #9, finished in the Prairie Du Chein/Jordan formation. Chlorine, fluoride, and polyphosphate for iron sequestering were added to the water at the well head at this time. The water had about 17 grains per gallon hardness and most residents had individual home water softeners.
The State Board of Health notified the City that the chemical contamination posed a long-term chronic health problem and directed the City to replace the contaminated supply. Replacement options investigated by the City included, purchasing water from a neighboring city, installation of new clean wells, and treatment of the existing supply. The City’s initial decision was to construct new wells in the deeper Mount Simon/Hinckley aquifer.
The City began in the fall of 1981 by sealing off the Prairie Du Chein/Jordan aquifer in Well #8 and Well #9 and drilling them into the deeper Mount Simon/Hinckley aquifer. Three additional Mount Simon/Hinckley wells, #10, #11 and #12, were constructed over the next couple of years. The Mount Simon/Hinckley wells had a lower yield than the Prairie Du Chein/Jordan wells and lawn sprinkling bans were in effect during the dry summer months. Odd/even lawn sprinkling continued to be enforced to moderate peak demands caused by lawn sprinkling. The Mount Simon/Hinckley water was also much higher in iron, so gravity iron removal filters were installed on wells #8, #10, #11, and #12.
By 1987 the source of the contamination had been identified as the Twin Cities Army Ammunition Plant (TCAAP) located in Arden Hills about 2.5 miles northeast of the City water wells. The Army reimbursed the City for the cost of the Mount Simon/Hinckley wells and iron removal plants and paid for the design, construction, and operation and maintenance of a new treatment plant to treat water from the old contaminated wells #3, #4, #5, and #6. The litigation settlement agreement between the city and the army requires the city to pump 3.2 to 6.9 million gallons daily for remediation purposes.
The water treatment plant was put into service in May of 1990. The treatment process utilizes granular activated carbon in down-flow pressure contactors to remove the contaminants.
The treatment plant proved to be a safe and reliable water supply for the City and an important groundwater cleanup facility for the Army. This practical relationship between water supply and groundwater cleanup resulted in a cooperative effort by the Army and the City for the final remediation plan for the contaminated Prairie Du Chein/Jordan aquifer. In 1992, well #13, a second smaller treatment plant, and a 20 inch diameter water system interconnection to the City of Fridley were completed. In 1994, iron and manganese pressure filtration was added to the first Treatment Plant. In 1995 and 1996 two additional new wells, #14 and #15, were installed to optimize contaminant removal and plume containment. The interconnection to the City of Fridley was built because the daily pumpage requirements for containment were in excess of the City of New Brighton’s average day water demand. The iron and manganese filtration was added because the best wells for remediation contain levels of iron and manganese that could not be satisfactorily controlled by sequestration. The large water treatment plant is referred to as the Permanent Granular Activated Carbon Water Treatment Facility, or by the acronym PGACWTF. The smaller water treatment plant is called the Plume Groundwater Recovery System, or PGRS. In the year 2000, the water from well #13 was tested clean of contamination, the well was sealed and the PGRS treatment plant was decommissioned.
New Brighton water demand records have been maintained since 1966. The average daily consumption over the period 1984 to 1994 is 120.8 gallons per capita per day. The average daily demand for this same period is 2,814,356 gallons per day. The maximum day demand of record of 9.3 million gallons occurred in July of 2001. Variations in the water demand for at least the last ten years have been primarily a result of weather and lawn sprinkling. These water demand figures are probably representative of the foreseeable future since the City of New Brighton is nearly fully developed and surrounded by developed communities.