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• Cost to construct 1000 lineal feet of drain tile system with pumps and controls is <br />estimated at $80,000. <br />• Operation and maintenance costs are estimated at $1,000 per year per system plus <br />2.5% of Capital Cost. <br />• Proposed construction costs reflect a 30% contingency for construction and a 25% <br />cost for indirect expenses relating to legal, administrative, and land acquisition. <br />• For estimating purposes, the cost for installation of 1,150 linear feet of infiltration <br />trench will be $100,000, and such a system will have the capability to annually <br />remove 100 acre feet of runoff volume and 100 pounds of total phosphorus from <br />the watershed. <br />Assumptions Associated with Water Quality Benefits <br />• Infiltration of one acre foot of runoff volume will result in one pound of <br />phosphorus removal <br />• For each acre of impervious surface that is added as part of a subdivision, if two <br />acre feet of runoff volume are infiltrated, the impact associated with that <br />subdivision will be fully mitigated. <br />• For each acre of existing impervious surface that is reconstructed and for which <br />infiltration is required as part of updated standards, a reduction of 2 pounds of <br />phosphorus will be assumed to occur a result of infiltration BMPs being <br />retroactively applied to the project. <br />• For purposes of estimating the annual cost for a BMP, 6.5% of the BMPs capital <br />costs will be used as the annual cost associated with the capital contribution. <br />Flocculation Treatment System <br />• For systems having a capacity to remove up to 10 pounds of phosphorus per <br />month, a cost of $1,300 per pound of phosphorus will be used. <br />• For flocculation systems having a capacity to remove 10-20 pounds per month, a <br />cost of $1,000 per pound of phosphorus removed will be used. <br />• For systems with removal rates of more than 20 pounds of phosphorus per month, <br />a cost of $800 per pound of phosphorus will be used. <br />• Flocculation treatment will be assumed to reduce phosphorus concentrations in <br />treated water to at or below 25 parts per billion. <br />CIP for Storm Water Projects Within the City of Hugo <br />City of Hugo, MN <br />WSB Project No. 1687-85 <br />Page 22 <br />