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To: Lanya Ross, Anneka LaBelle, Ali Elhassan <br />From: Evan Christianson, Ray Wuolo <br />Subject: Metro Pumping Optimization 3 <br />Date: April 2, 2015 <br />Page: 3 <br />Table 2. Comparison of constraints between Optimization 1, 2, and 3 <br />Constraint Type <br />Optimization <br />1 <br />Optimization <br />2 <br />Optimization <br />3 <br />Drawdown from available head for confined bedrock aquifers <br />above the Mt. Simon -Hinckley <br />75% <br />75% <br />50% <br />Drawdown in the Mt. Simon -Hinckley aquifer <br />1 foot <br />1 foot <br />1 foot <br />Drawdown at groundwater dependent surface -water features <br />(cancerous fens) <br />1 foot <br />1 foot <br />1 foot <br />Change in net baseflow to trout streams <br />-10% <br />-10% <br />-10% <br />Change in net baseflow to other river reaches <br />Not included <br />-15% <br />-15% <br />Change in net baseflow to the Mississippi River <br />Not included <br />-15% <br />-25% <br />Change in net groundwater flux for high and outstanding <br />biodiversity <br />Not included <br />-15% <br />-15% <br />Change in net groundwater flux to potentially vulnerable lakes <br />with wide littoral zone <br />Not included <br />-10% <br />-10% <br />Change in net groundwater flux for remaining lakes at grouped <br />by Township <br />Not Included <br />-15% <br />-15% <br />Change in flow directions at site of groundwater contamination <br />10 degrees <br />10 degrees <br />10 degrees <br />Optimization 1 constrained the flux between groundwater and surface water for trout streams only. As <br />described in more detail below, Optimizations 2 and 3 constrained the flux between groundwater and <br />surface water for all lakes, streams, and wetlands simulated by Metro Model 3 within the seven -county <br />metropolitan area. <br />2.2.1 Hydraulic Head Constraints <br />Hydraulic head constraints were used to impose three conditions on the optimization: 1) hydraulic head in <br />confined bedrock aquifers can't drop below a "safe yield" threshold, 2) hydraulic head in the Mt. Simon— <br />Hinckley aquifer can't drop more than 1 foot from the baseline condition, and 3) hydraulic head at <br />groundwater dependent surface -water features (e.g. calcareous fens) can't drop more than 1 foot from <br />the baseline condition. Hydraulic head, representing "safe yield" thresholds, were defined as: <br />Safe Yield Head = (Hb — Z) * 0.50 + Z <br />Where: <br />Hb is the base head condition for the aquifer, defined using pumping from the Metro Model 2; <br />Z is the elevation of the top of the aquifer <br />