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WSB & Associates, hie. Infi'astructure ® Engineering ® Planning 8 Construction July 21, 2005 I3onorable Mayor, City Council and Staff City of St. Anthony Village 3301 Silver Lake Road NE Minneapolis, MN 55418-1603 Re: Sanitary Sewer Inflow/Infiltration Update St. Anthony Village, MN WSB Project No. 1.065-57 Dear Mr. ;Mayor, City Council, and Staff: 701 Xenia Avenue South Suite 300 Minneapolis, MN 55416 Tel: 763-541-4800 Fax: 763-541 1700 The purpose of this letter is to update the City of St. Anthony Village on the status of the Trrflow/hifiitration (1/1) reduction plan and to determine if the City is meeting the III goal set by the Metropolitan. Council Environmental Services (MCES), By way of background the primary source of clear water I/I within the City is the illegal connection of residential sump pumps and passive drain the into the saintary sewer system. It is estimated that approximately 1500 homes within the City have these illegal connections. These connections have caused increased sanitary sewer flows during large rainfall events, which have exceeded. the allowable flows set by MCES. The MCES has established UI goals for each community discharging wastewater into the Metropolitan Disposal System. The table below shows the 1'/I calculation for the City of St. Anthony during a specific storm event in April 2001, MCLS ST. ANTHONY FLOW INFORMATION The sanitary sewer flow data from the MCES was analyzed over the past ten years to determine any trends in the reduction of clear water entering the system. From reviewing the data, there has been a decrease in the sewer flow spikes after significant rainfall events caused by clear water I/I, This coincides with the drop in violations of the 1/.1 goal recorded by MCES. In 2004 there were three violations recorded on June 12, 13, and July 11 at meter 104. There have been no UI violations recorded for the first half of 2005, in which the City has received 11.62 inches of rain from April through June. Minneapolis 3 St. Cloud r,ivrwrx11065-m2005i072105 navy,, c, Equal Opportunity Employer I METER ALLOWABLE PEAK RESULTING PEAK HOUR FLOW (MGD) HOUR FLOW (MGD) 55 1.19 1.4 55A 0.33 >0.97 104 --- ------ ---- 1.59 2.82 105 _... 012 ---0.21 The sanitary sewer flow data from the MCES was analyzed over the past ten years to determine any trends in the reduction of clear water entering the system. From reviewing the data, there has been a decrease in the sewer flow spikes after significant rainfall events caused by clear water I/I, This coincides with the drop in violations of the 1/.1 goal recorded by MCES. In 2004 there were three violations recorded on June 12, 13, and July 11 at meter 104. There have been no UI violations recorded for the first half of 2005, in which the City has received 11.62 inches of rain from April through June. Minneapolis 3 St. Cloud r,ivrwrx11065-m2005i072105 navy,, c, Equal Opportunity Employer