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Mr. Thomas M. Sweeney Sweeney, O'Connor & LeMay July 9, 1984 Page Two ,. Bypassing at L -8 to a. Bounty ditch and thence to Lake Kohlman was as follows: 1. 9 p.m. June 7 to 3 a.m. June 9 30 hours 2. 6:50 p.m. June 9 to 8:20 a.m. June 10 132 hours 3. 8 a.m. June 12 to 8:20 p.m. June 13 362 hours Total Duration = 80 hours Estimated Flow Rate = 300 gpm (twice normal) Estimated Volume = 1,400,000 gallons A short duration bypass to the nearby swamp occurred at L -10 following the June 7 rainstorm. Bypass duration was 21 hours and estimated bypass volume was 80,000 gallons. Since the flows were about twice normal due to I /I, the quality of water bypassed was about half the strength of normal wastewater. Impacts on Lakes Gervais and Kohlman was minimal given the weak strength of the bypass and the large dilution by the lakes. The only alternative to bypassing would have been to flood basements, but it should be noted that wastewater flows were so high during the June 7 -13 period that bypass- ing would have occurred even if basements had been allowed to flood. NPDES Permit and Related Issues The Little Canada interceptor system is covered by the Metropolitan Plant NPDES Permit No. MN0029815. Part II.A.2 states: "The diversion or bypass of any discharge from the collection system or treatment facility by the Commission is prohibited, except: (1) where unavoidable to prevent loss of life or severe property damage...." The circumstances in June presented a public health hazard and property damage concern, because basement flooding would have been widespread if limited bypass- ing had not occurred. All of the Commission's lift stations and sewers were functioning properly and at maximum capacity. Thus, it was necessary for the Commission to use bypassing as a last resort, given the excessive wastewater flows being received. The Commission's Waste Discharge Rules prohibit the discharge of unpolluted water, such as rain water, storm water, or groundwater (foundation drains) unless there is no prudent and feasible alternative. Each community implements its own sewer use ordinance, over which the Commission has no direct control. As a result, situations can occur whereby excessive flows reach the Commission's interceptors and overload the system, as happened in the Little Canada interceptor system during June. Status of Capital Improvements Projects There are two incinerator projects that are planned to provide additional wastewater conveyance capacity for Little Canada and upstream communities. These projects are the Lake Gervais Interceptor and the Lower Beltline Interceptor. Both projects have been designed. Both projects are expected to be completed and operational by mid - 1986.