Minutes - Public Works Committee - 04/16/2002

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the City of Ramsey's system. In 1997, the cities of Ramsey, Anoka, Blaine, Centerville, Circle Pines, Coon Rapids, Fridley, Lexington, Lino Lakes, Spring Lake Park, and Anoka County entered into a Joint Powers Agreement to form the Anoka County Municipals Wellhead Planning Group. Wellhead planning requires detailed groundwater modeling to determine ground water movement and well recharge access. Since cities in the Anoka sand plain share a common geology, it was felt that money could be saved by hiring one entity to prepare the ground water modeling. Subsequently, the Department of Health received funds for it to underwrite the cost of this modeling and plan development. The work performed to date has been at no cost to the City other than staff time. At this point the groundwater modeling and preliminary inventories have been completed. Three important determinations have been made. Inner Wellhead Management Zone: This is a distance of up to 200 feet around each well. This area is inventoried for 59 conditions or potential hazards. All four of the City wells are in compliance with all of the conditions. In the future, the City will be required to maintain these separations for new potential contaminant sources. Additional recommendations are that a six-foot chain link fence to secure a 50-foot area around the well from vehicle hauling contaminants. Well Vulnerability: Wells are classified as either being vulnerable or not vulnerable. Classifications are based upon a number of factors including well construction and condition, water quality history, and the sensitivity of the geology to contamination. The results of the vulnerability assessment for Ramsey's wells are that wells one and two are not vulnerable, while wells 3, 4, and 5 are vulnerable. The reason for the vulnerability stems from the presence of a detectable level of tritium in the water. Tritium is a naturally occurring isotope of hydrogen, which is mildly radioactive. Since nuclear testing in the atmosphere began in 1953, there has been a detectable increase in the level of tritium. Since hydrogen is incorporated into a water molecule it can be used as an indicate of the age of groundwater. The significance of having a vulnerable well versus one that is not vulnerable, is that vulnerable wells will require additional measures when implementing a well protection plan. All wells will require a public education program and must have an inventory of well within the wellhead protection management area. In addition, vulnerable wells would likely need to inventory underground tanks, monitor septic systems, and identify hazardous waste generators within the wellhead protection area. Drinking Water Supply Management Area: Based upon the groundwater modeling an area know as a wellhead protection area has been defined. This is the extent of the area from which the well will draw water over a ten-year period at its projected pumping rate. At this point the City must request approval of the work done to date, which include the wellhead protection area delineation, the drinking water supply management area delineation and the vulnerability assessment. Following this the City will need to work with the Department of Health in developing a wellhead protection plan to be implemented within the drinking water supply management area. Councilmember Anderson inquired if a deeper aquifer would eliminate the need for a water treatment facility. Principal City Engineer Olson replied no. Councilmember Zimmerman inquired as to what the timing of events were. Public Works Committee/April 16, 2002 Page 9 of 12