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<br />. <br /> <br />_ / f ~ ~ ~ ~. CONSULTING ENGINEERS <br /> <br />~_I Maier Stewart & Associates Inc. <br />February 8, 1993 <br />File: 230-151-80 <br /> <br />Mr. Pat Klaers <br />City Administrator <br />City of Elk River <br />720 Dodge Avenue NW <br />Elk River, MN 55330 <br /> <br />RE: NON-DEGRADATION RULES FOR OUTSTANDING RESOURCE VALUE WATERS <br /> <br />Dear Mr. Klaers: <br /> <br />As you know, the reach of the Mississippi River that receives the City's treated effluent has <br />been designated an "outstanding resource value" water. In fact, the entire reach of the <br />Mississippi River from St. Cloud to the Anoka City limits has been designated an "outstanding <br />resource value" water. Non-degradation rules apply to these waters. In simple terms, the <br />non-degradation rules state that there shall not be an increase in the total pounds of <br />biochemical oxygen demand (BOD) associated with a municipality's effluent discharge. Elk <br />River's current NPDES permit allows a discharge of98.3 kilograms (216.84 pounds) of BOD <br />. per day. The 216.84 pounds was determined according to the following equation: <br /> <br />lb. BOD/day = BOD concentration in mg/l x flow in millions of gallons per day x 8.34 <br /> <br />Filling in the permitted BOD concentration of 25 mg/l and the permitted flow of 1.04 <br />MGD completes the equation: <br /> <br />lb. BOD/day = 25 mg/l x 1.04 MGD x 8.34 = 216.84 <br /> <br />If the total pounds of BOD per day cannot increase, it becomes apparent from this equation <br />that as flow increases, the permissible BOD concentration must decrease. The City Council <br />has indicated a desire for up to a 3 MGD wastewater treatment facility. An increase from <br />roughly 1 MGD to 3 MGD will result in a permissible BOD concentration of approximately <br />9 mg/l (25 mg/l -:- 3). Achieving this or any level of BOD removal over approximately 1.75 <br />MGD will result in a more expensive wastewater treatment facility (WWTF). <br /> <br />There are some alternatives to constructing a WWTF to meet this more stringent BOD <br />concentration. These alternatives include: <br /> <br />. Construction of a controlled discharge treatment facility (stabilization pond system) <br /> <br />. <br /> <br />· Construction of a land application treatment facility. <br /> <br />1959 SLOAN PLACE, SUITE 200, ST. PAUL, MINNESOTA 55117 612-774-6021 <br />9800 SHELARD. PARKWAY, SUITE 102, MINNEAPOLIS, MINNESOTA 55441 612-546-0432 . Equal Opportunity Employer <br /> <br />151-080l.feb <br />