Agenda - Environmental Policy Board - 10/15/2018

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wells around the Town Center are high. The high levels may be caused by the rapid rate of infiltration through the highly permeable sand and gravel materials of the Anoka Sand Plain, or by the interaction of the quaternary and bedrock aquifers in the bedrock valley to the north of the site. Water quality tests of Ramsey public water supply wells including tests for nitrates, pesticides, volatile organic compounds, and arsenic were found to meet all of the Safe Drinking Water Act drinking water limits. Manganese and iron are present and may produce staining and metallic tasting water, but do not pose a health risk. Clay layers in the glacial material and shale layers in the Franconia Formation slow or impede the course of potential surface pollutants towards the lower bedrock formations and therefore help to maintain the quality of the Ramsey water supply. Summary of Environmental Impact. There were no geologic hazards within the Town Center site. A bedrock valley was identified by the MGS approximately a mile and a half north of the Town Center. Due to the high permeability of the Anoka Sand Plain, the surficial aquifer is susceptible to contamination from surface activities. This contamination could potentially reach the water supply. The following mitigation plan details means to minimize the risk of contamination. Mitigation element. The high permeability of the soils at the Town Center are ideal for the implementation of infiltration practices that will manage stormwater runoff, provide flood control and recharge the water table aquifer. However, the high permeability also increases the risk for potential contamination of groundwater resources. In order to mitigate this risk, best management practices (BMPs) and community education piugiains will be implemented. Extensive use of herbicides, pesticides, and fertilizers on residential and public lawns, and agricultural fields is discouraged in the City of Ramsey, as stated in the City's 2001 Comprehensive Plan. Implementing community education and awareness programs to discourage the above stated activities, as well as to inform on household and business chemical usage and hazardous waste storage and disposal will help reduce the potential for groundwater contamination by these types of substances. The appropriate use of native vegetation will also reduce the need for herbicides, pesticides and fertilizer throughout the Town Center. Infiltration of stormwater under carefully managed conditions is essential for recharging groundwater. Infiltration through soil also removes nutrients and other potential pollutants from surface water, pretreating and maintaining the quality of the water. Potential groundwater contaminants from stormwater runoff associated with land uses similar to the proposed Town Center land uses include nitrates, pesticides, organic compounds, and heavy metals. The potential for contamination from these substances is greatly reduced when stormwater runoff is pre-treated prior to infiltration and BMPs are implemented. Pretreatment methods vary, but include the use of permeable materials to promote infiltration and pollutant removal by soil, vegetation to filter surface water, settling to remove solids and pollutants associated with them, and preventative measures 19-3