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<br />Prepared by: Bolton & Menk, Inc. MCM 6: POND ASSESSMENT PLAN <br />Orono SWPPP ǀ 0C1.126140 Page 1 <br />VI. MCM 6: POND ASSESSMENT PLAN <br /> Assessment Procedures <br />1. Determine Existing Conditions <br />a) Delineate watersheds for every pond maintained by City. <br />· Review Storm Sewer Map <br />· Review LiDAR topographic mapping <br />· Perform visual inspections <br />b) Define watershed characteristics (impervious surface percentage, time-of- <br />concentrations, areas, soil types, etc.). <br />· Review aerial mapping <br />· Review Land Use Plan <br />· Review Storm Sewer Map <br />· Review LiDAR topographic mapping <br />· Perform visual inspections <br />c) Define pond characteristics (design permanent volume, existing permanent <br />volume, outlet, normal water level, etc.). <br />· Review Construction Plans and Record Plans <br />· Perform visual inspections <br />· Perform site surveys <br />· Perform bathymetric surveys <br />· Perform sediment testing for pollutants <br />2. Assess TSS and TP Treatment Effectiveness <br />a) Create water quality models for every pond maintained by City <br />· Input information gathered into models <br />· Calculate TSS and TP removal efficiencies <br />b) Define TSS and TP treatment effectiveness required for every pond <br />· Establish permanent volumes required to meet NURP standards (60% <br />TSS removal, 62% PP removal, 34% TP removal) <br />· Determine additional reductions required to meet TMDLs, if any <br />· Determine additional reductions required to provide increased water <br />quality benefits <br />c) Rate pond effectiveness / need for maintenance <br />· MN Stormwater Manual recommends sediment removal after 50% <br />of permanent pool capacity has been lost <br />· Compare existing removal efficiencies to required efficiencies