AN EVOLVING BIOSOLIDS MANAGEMENT PLAN: THE SOUTH VALLEY WATER RECLAMATION FACILITY STORY
Abstract:The South Valley Water Reclamation Facility (SVWRF) is a 38 million gallons per day (mgd) oxidation ditch wastewater reclamation facility that services five communities in the south of Salt Lake City, Utah Valley. The facility produces approximately 120 wet tons per day of 15 percent solids biosolids. The facility is managed by a Board comprised of representatives from each of the member communities and run by a professional staff. This paper will report the flexibility required to manage the biosolids under a series of changing environmental, regulatory, and economic restraints.
When the facility was first designed in the mid-1980s, a remote site approximately nine miles from the wastewater treatment plant was chosen for a SVWRF-owned dedicated monofill site. This site in the South Jordan City community was adjacent to the TransJordan Landfill and, at the time of construction, was quite isolated, as was the wastewater treatment plant site itself. This method of biosolids management worked quite well for a number of years in that it was inexpensive, did not cause environmental complaints, and met all regulatory criteria. In about 1997, the SVWRF was forced to look again at its biosolids management plan when it observed that the land permitted for the monofill was rapidly being depleted and the landfilled biosolids were not decomposing as expected. When one of the trenches was excavated, it was found that no decomposition or dewatering had occurred despite the arid, hot environment.
Given the depletion of the landfill space, the SVWRF undertook a series of activities in 1998 designed to address the biosolids issues. The first activity was to design a compost pad on unused space at the Lark site. Simultaneously with designing the site, the SVWRF negotiated a five-year agreement with the TransJordan Landfill, whereby TransJordan would send yard waste to a processing facility run by the SVWRF and jointly funded by both TransJordan and SVWRF. SVWRF would then utilize the processed yard waste as a bulking agent for the biosolids. SVWRF windrowed the material and, after overcoming initial odor and temperature problems, developed a process whereby 75 percent of the compost produced met Class B criteria and 25 percent of the compost produced met Class A Exceptional Quality criteria for public distribution. The Class B compost was sent to the Kennecott Copper Company under an agreement whereby Kennecott would accept the material at no cost and utilize it as part of Kennecott's revegetation process. The agreement with Kennecott had a 30-day cancellation clause that put the SVWRF at risk.
The second activity undertaken in 1998 by the SVWRF was to advertise for consultants to develop a long-range plan. The SVWRF eventually chose Montgomery Watson with E&A Environmental Consultants, Inc. (E&A) as a subconsultant to develop the biosolids management plan. While the plan was being developed, the SVWRF had the opportunity to sign a two-year contract with ET Technologies in western Salt Lake City to utilize the biosolids to build soil for use as a final landfill cover for Salt Lake County. This agreement had the advantages of a favorable price and allowing the SVWRF to cease monofilling biosolids.
During the development of the biosolids plan, the State of Utah regulatory authorities visited the Kennecott revegetation site and ordered them to stop stockpiling the Class B compost until the existing stockpile was removed. This order effectively removed this biosolids treatment option and forced the SVWRF to concentrate on improving its Class A compost process and exploring methods of reducing space requirements and odor generation from the compost site.
In late 2000, the SVWRF initiated a cooperative pilot study with Kennecott on Kennecott property whereby a Class B alkaline-stabilization product was formed to be used to reclaim acid mine spoils. The seeding of these plots took place in early 2001.
In March 2001, the SVWRF was notified by ET Technologies that the costs to process biosolids would double and there would be no guarantee of a volume to be handled. Simultaneously with this decision, the SVWRF decided to have E&A develop a conceptual design to convert the existing windrow compost operation into a static pile facility with biofilters for odor control.
The paper will present costs and rationale for the various changes in the SVWRF's biosolids management approach and show that with cooperative and innovative negotiations with regulators, processors, and end users, a cost-effective biosolids program can be developed with the flexibility to evolve into a new phase as new constraints occur.
Document Type: Research Article
Publication date: January 1, 2002
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