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Implementation Highlight: Exploring Impacts of Infiltrating Reclaimed Water on <br />Groundwater and Surface Water in the Southeast Metro <br />The Twin Cities metropolitan area Master Water Supply Plan identifies <br />investigating the reuse of wastewater as a strategy for achieving sustainable <br />water supplies and supporting the Water Resources Policy Plan policy on <br />conservation and reuse. <br />One project that highlights this work, led and funded by the Metropolitan <br />Council Environmental Services Technical Services group, was an analysis <br />exploring the impacts of infiltrating reclaimed water on groundwater and surface <br />water in the Southeast Metro. <br />Objective <br />Answer Metropolitan Council Environmental Services' Southeast Metro <br />customers' question: can infiltrating water lessen projected future groundwater <br />level drawdown and surface water level impacts? <br />Southeast Metro communities depend on groundwater for drinking water. They <br />have sought ways to avoid or lessen potential future issues such as <br />groundwater level drawdown. Infiltrating highly treated wastewater (reclaimed <br />water) may be one method that helps avoid or lessens potential future <br />groundwater level drawdown and surface water impacts due to pumping. <br />0, <br />1,01 <br />STEP 1 <br />Build on <br />previous study <br />and tools <br />STEP 2 <br />Identify <br />potential <br />infiltration sites <br />STEP 3 <br />Assess <br />impacts of <br />infiltration <br />STEP 4 <br />Explore results <br />in Dakota <br />County <br />LJ <br />Model results were <br />mapped and stored <br />in a map library. <br />Maps can be filtered/ <br />searched to identify <br />impacts of infiltration <br />at any given site. <br />Infiltration can reduce <br />the negative impacts <br />of groundwater <br />pumping on aquifer <br />and surface water <br />levels <br />THE MAPS SHOW: <br />There are some <br />areas where <br />infiltration could be <br />beneficial to both <br />aquifers and surface <br />water levels <br />Infiltration's impact <br />depends on the rate <br />of infiltration. Rate <br />of 1 MGD had little <br />benefit, 10 MGD had <br />greater benefit but <br />mounding occured. <br />5 0y • <br />1`F • <br />\ rw • <br />14 <br />S' . <br />Maintaining stream/lake <br />inflow: <br />6 Least Benefit <br />Most Benefit <br />. 414°' 4rtik <br />;;'?.. _ may- -, ' <br />Infiltration Rate: 10 MGD <br />El Surface water <br />• <br />Site removed from <br />consideration: unwanted impacts <br />Figure 16. Process steps (above) and examples of maps generated by this project (left). <br />Offsetting aquifer <br />decline due to pumping: <br />rilLeast Benefit <br />Most Benefit <br />2 `, <br />Ides <br />0 Site not evaluated <br />based on prior work <br />Page - 27 I METROPOLITAN COUNCIL <br />