04-10-2023 Council Packet - Laserfiche WebLink

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Prepared by: Bolton & Menk, Inc. MCM 6: POND ASSESSMENT PLAN Orono SWPPP ǀ 0C1.126140 Page 2 · Review proximity to surface waters · Review proximity to Impaired waters · Review TMDL requirements · Determine Management Level of Sediment · Rate pond based on following system: Table 1 – Pond Rating System Rating Description 1 · Pond completely ineffective · Pollutant removal efficiency reduced well below 50 % NURP / required standards (60% reduction or more) · Efficiency reduced below 50% NURP / required standards (50-60% reduction) and discharges directly to surface water or located in Impaired Water watershed · Maintenance required as soon as possible to prevent further pollutant discharge 2 · Pollutant removal efficiency reduced below 50% NURP / required standards (50-60% reduction) but does not discharge directly to surface water and is not located in Impaired Water watershed · Pollutant removal efficiency reduced to approximately 50% NURP / required standards and discharges directly to surface water or located in Impaired Water watershed · Maintenance should be provided as soon as funds are available 3 · Pollutant removal efficiency reduced to approximately 50% NURP / required standards · Does not discharge directly to surface water and not located in Impaired Water watershed · Maintenance should be planned for near future 4 · Pollutant removal efficiency reduction approaching 50% NURP / required standards (25-50% reduction) · Pond should be checked yearly to monitor permanent pool volume reduction and determine if change in rating is necessary 5 · Pond recently constructed or dredged, pollutant removal efficiency at maximum level (0-25% reduction) · Pond should be checked for permanent pool volume capacity starting 5 years after initial construction or dredging and every 5 years after until rating decrease is warranted Schedule 1. Determine Existing Conditions 2. Assess TSS and TP Effectiveness