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Author      Title/Abstract      

Evaluating Management Options for Improving Cost-Effectiveness at METROGRO Farm
Author: Nikki A. Crews, Bryan W. Mitchell, Steve Wilson
Date: 6/311
Preprint, WEF/AWWA Joint Residuals and Biosolids Management Conference 2011 May 22-25, 2011, Sacramento, CA

The Metro Wastewater Reclamation District (Metro District) in Denver, Colorado is the largest metropolitan wastewater treatment facility between the Mississippi river and the west coast. The Metro District’s Robert W. Hite Treatment Facility (RWHTF) treats approximately 140 million gallons of wastewater and produces an average of 80 dry tons of biosolids per day. The Metro District operates an aggressive biosolids management program. The METROGRO Farm (Farm) serves as one outlet for its biosolids management program. The Farm is a 52,000 acre, or 80 square-mile piece of agricultural real estate owned by the Metro District. The Metro District purchased the Farm during the mid-1990s when availability to apply biosolids to private farm land was uncertain. A tenant farmer operates the entire Farm for the Metro District. He grows predominantly dryland wheat in a wheat-fallow rotation and on occasion, he plants a spring crop such as millet or corn. Sheep and cattle grazing also take place in the non-cultivated areas of the Farm. The Farm receives varying quantities of Class B biosolids product from year to year with input received from the tenant farmer. As many conditions have changed since the property was acquired, the Metro District evaluated farm management techniques and lease terms as one initiative of an extensive Biosolids Optimization and Diversification Study. The Metro District produced approximately 25,000 dry tons (DT) of biosolids in 2010. Three primary outlets for the biosolids program were as follows: • METROGRO Farm – 7,695 DT (31%) • Private agricultural land – 15,791 DT (64%) • Private composting facility – 1,400 DT (5%) Capacity for biosolids application at the Farm is limited to accessible land. The bulk of accessible acreage is a direct result of the tenant farmer’s dryland wheat-fallow crop cycle. Of the 28,000 acres of cultivated land on the Farm, approximately 14,000 acres is available for biosolids application in a given year. Seasonal field conditions and crop management schedules further limit land availability. Meanwhile, rising fertilizer costs and proven benefits of biosolids as a fertilizer and soil amendment have stimulated demand by private land owners. Over 54,000 acres of private land have been approved by the Colorado Department of Public Health & Environment for the Metro District to land apply biosolids. Private sites provide an important supplement for biosolids acreage capacity at the Farm. To optimize the current METROGRO Farm operation, several changes are under consideration: • Modify cropping practices to return marginal lands to permanent grass with potential for increased biosolids utilization • Renegotiate lease terms to provide the Metro District with a reliable fixed income (cash- rent basis) and reduce the level of participation in funding operating costs for no-till farming • Develop wind power to provide additional revenue in the form of royalty payments Additional biosolids management outlets including a thermally dried Class A product and contract private composter expansion are being considered under additional initiatives of the Biosolids Optimization and Diversification Study.

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