Agenda - Council - 03/10/2015 - Laserfiche WebLink

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MPCA. Because the Minnesota River, which flows into the Mississippi River, already contains approximately 0.2 mg/I phosphorus, the Mississippi River will likely continue to fail to meet standards unless the Minnesota River quality improves significantly. As a regulatory consequence, wastewater treatment discharge could be required to meet the water quality standard as a discharge limit. Achieving compliance with a 0.3 mg/I phosphorus limit requires additional facilities for chemical addition, pumping, filtration, and solids processing facilities. Estimated capital cost (current prices) for the Council's wastewater treatment plants is $400 million. Estimated annual operation and maintenance cost is an additional $15 million. Achieving compliance with a 0.1 mg/I phosphorus limit requires investments for chemical addition, tertiary clarifiers, pumping, membrane filtration, and solids processing facilities. Estimated capital costs (current prices) for the Council's wastewater treatment plants are approximately $2 billion. Estimated annual operation and maintenance costs are approximately an additional $30 million. Total annual operation and maintenance costs, plus annual debt service on the capital, are estimated at approximately $45 million for 0.3 mg/I phosphorus limit and $180 million for 0.1 mg/I phosphorus limit. These potential costs would raise regional wastewater rates by 40% to 100%. Nitrogen. The Minnesota Pollution Control Agency is considering a water quality standard for nitrate nitrogen based on levels considered toxic for aquatic life. The Minnesota Pollution Control Agency with assistance and guidance from the U.S. Environmental Protection Agency recently developed a nutrient reduction strategy for the Mississippi River watershed to protect the Gulf of Mexico. Nitrate is a nutrient necessary for aquatic growth, but excessive amounts can lead to problems such as algae blooms, decreased oxygen levels, and fish kills. Currently, the Council's wastewater treatment plants meet seasonal effluent limits for ammonia nitrogen, to meet a water quality standard for ammonia nitrogen based on toxicity for aquatic life. The wastewater treatment plants use biological treatment to convert ammonia to nitrate nitrogen, with average nitrate discharge of 15 to 20 mg/I. If the Minnesota Pollution Control Agency adopts a nitrate nitrogen standard, the Mississippi River will likely continue to fail to meet standards because the Minnesota River contributes most of the nitrate nitrogen loading to the Mississippi River. As a regulatory consequence, wastewater treatment plant discharges could be required to meet the water quality standard as a discharge limit. Meeting this standard would require major capital improvements to remove nitrate by a biological denitrification process. A small change in specific concentration limits of nitrate nitrogen and total nitrogen would result in a correspondingly large change in costs. Changes to the biological treatment process would also affect the performance of treatment plants to remove phosphorus. Estimated capital costs are approximately $1.0 billion to meet a 10 mg/I total nitrogen limit and approximately $1.5 billion to meet a 5 mg/I total nitrogen limit. Substantial Impacts and Substantial Departures from the Metropolitan Wastewater System Plan Thrive MSP 2040 and the regional system plans comprise the Council's Metropolitan Development Guide, which is the region's plan to ensure orderly and economical development 44