You Gotta be Flexible to be Sustainable
Abstract:Metro Wastewater Reclamation District (Metro District) in Denver, CO is the largest metropolitan wastewater treatment facility between the Mississippi river and the west coast. The Metro District 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, which includes land application of biosolids on the METROGRO Farm (Farm). 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 in order to always have a place to land apply its biosolids. A tenant farmer farms the entire Farm for the Metro District. He grows mostly 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.
Colorado has been experiencing a drought for the last five years and crop production has suffered ill effects. The crop production on the Farm has been on a steady decline since 2003, hitting its lowest point in 2006. Low crop production translates into higher available residual nutrients in the soil profile. With higher residual nutrients left in the soil profile after a crop harvest, the need for fertilization decreases. The Farm has experienced this effect with fewer fields needing fertilization since 2003.
The Metro District also land applied to a handful of private agriculture sites, and realizing there was a potential problem at the Farm related to the drought, Metro District staff set in motion to gain additional private farm sites. Developing a strong private farmer base would ensure sustainability of the land application program. Securing private farm sites in various eastern plains counties would allow continual land application by providing an additional safeguard from typical Colorado sporadic weather events. A migration began from land applying most of the Metro District's biosolids to the Farm to land applying the majority of its biosolids to private farm sites.
The private farm land application program was off to a great start when, in late December 2006 and early January 2007, the Denver area and eastern plains of Colorado were hit with two consecutive heaviest snow storms in history coupled with extremely cold temperatures. Even though several private farm sites had been established and the Metro District felt comfortable with their land base for application of biosolids, the extreme winter weather prevented any land application of biosolids for two months. The geographic area impacted by the snow storms was so significantly widespread; the geographic diversity of the newest land application sites was immaterial. Land application was suspended, but the Metro District was still producing 80 dry tons each day.
The need for diversity was apparent and Metro District management was flexible in its efforts to maintain the integrity and sustainability of its biosolids management program. Key planning for short and long-term operations and follow-up were imperative for the success of the private farm land application program.
Flexibility was the only way to handle this situation. The Metro District's “on the spot” ability and willingness to adjust the day-to-day operations was not an option. The Environmental Management System (EMS) provided an excellent venue and comprehensive starting point for Metro District staff to brainstorm several management alternatives to get through the harsh winter. The EMS also kept Metro District staff on the right track and ensured that management alternatives used for managing daily biosolids production were in compliance with all applicable regulations and would not jeopardize the integrity of their national award winning biosolids management program.
Flexibility and willingness to change the day-to-day operation and utilization of alternative management methods are a vital component to the sustainability of the Metro District's successful biosolids management program.
Document Type: Research Article
Publication date: 2008-01-01
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