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D4.1 Iron and Manganese Iron and manganese do not pose a health problem, however, they can adversely affect maintenance costs and water aesthetics and are considered a secondary treatment standard by the Minnesota Department of Health (MDH). Five of the six cities add polyphosphates at the wellhead in order to limit iron and manganese precipitation in the distribution system. The City of Circle Pines operates a water treatment plant at Well No. 2 which uses greensand filters to remove iron and manganese. Before any two water systems are combined, further investigation is needed to determine whether combining and mixing water supplies would have negative effects to water quality. It is possible that combining the two treatment strategies may pose a problem in mixing water supply from Circle Pines with water from the rest of the cities. D4.2 Chlorine and Fluoride Addition All six cities add chlorine and fluoride to their drinking water in accordance with the Minnesota Department of Health (MDH) guidelines. D4.3 Hardness Hardness is considered a secondary drinking water standard and does not pose a health threat, however it may pose an economic problem as customers use more soap and detergent to overcome its effects. Water softening is not done by any of the six cities involved in this study. D5 Water Distribution System The distribution system is comprised of buried watermain piping, hydrants, valves, service lines, meters and pumping facilities. The existing distribution system is depicted in Figure A4. D5.1 Piping Network There are several areas in the existing watermain distribution system which are not looped, or connected back to each other, which results in dead end piping. Looping watermain systems helps to improve water quality and reduce water age in the system. Many of the dead end watermains are located near the municipal border. This is one opportunity for potential improvement through a joint water system. D5.2 Water System Interconnects Most of the cities in this study have interconnections with one or more cities. Existing connections between the cities make a joint system easier to develop. However, additional interconnections are likely to be a component of the joint system to facility higher capacity water flow between the cities and better movement within the system. Existing interconnects are shown in Figure A4. The City of Columbus does not have any interconnects with another water system. Existing interconnects are typically used for emergency scenarios, however, the City of Lexington shares an interconnection with the City of Blaine which it uses as a key component of its water supply. The City of Lexington operates their well only during the spring, summer and fall months and typically relies on Blaine for water during the winter months. Joint Water Utility Feasibility Study i]-5