San Antonio River Authority selected Texas Disposal Systems to build, own and operate a windrow facility on a former 52-acre biosolids land application site.
Jim Doersam and Paul Gregory
BioCycle March/April 2016
The San Antonio River Authority (SARA) is known in South Texas for being “Leaders in Watershed Solutions.” Its responsibilities include monitoring water quality, flood control and the operations and maintenance of its miles of hike, bike and paddling trails along the San Antonio River. SARA also owns and operates a wastewater utility that includes six municipal wastewater treatment plants (WWTPs) requiring either disposal or beneficial use of approximately 10,000 wet tons of biosolids annually. Until recently the residuals had been disposed in a permitted municipal solid waste landfill (MSW), but since April 2015 all of SARA’s biosolids have been composted and beneficially reused under a new public/private partnership with Texas Disposal Systems, Inc., a local solid waste hauling, disposal, composting and recycling company.
Request For Composting Services
In 2012, SARA released a request for proposals to repurpose a 52-acre agricultural land application site for a new composting/recycling facility adjacent to its Martinez II WWTP, approximately 13 miles east of downtown San Antonio. Texas Disposal Systems (TDS) responded with a proposal to design, construct and operate a new combined composting and recycling facility, and the contract (executed with TDS’ sister company, Texas Landfill Management, LLC) was approved in January 2014. Design, permitting and construction activities required an additional 16 months, and composting operations commenced in April 2015. The contract term is for 30 years, with two, 10-year options for renewal. Elements of the agreement are outlined in the sidebar.
TDS is one of the largest, independently owned and operated solid waste collection, processing and disposal companies in the nation. It operates a fully integrated facility in Creedmoor, about 20 miles from Austin, which includes a landfill, composting site and a materials recovery facility. The integrated facility services the surrounding Central Texas area. TDS has other facilities in north San Antonio, Victoria, San Angelo, Alpine, and Southeast Texas communities. In addition to its composting operations, TDS markets compost, mulch, soils, organic gardening supplies, trees and gardening-related gifts through its Garden-Ville™ stores located in the Central Texas region.
The new 52-acre Martinez II Composting and Recycling Facility includes a 6-acre compost pad permitted to process various materials, including: yard trimmings, biosolids, liquid, solid food waste, dead animals, paper, animal manure, and other materials as allowed under the Texas Commission on Environmental Quality (TCEQ) composting rules. These materials are generated by both the public and private sectors, and are hauled to the facility on a daily basis.
Composting is done in windrows turned by a Scarab Model 18. The primary source of bulking agents is chipped yard trimmings from the City of San Antonio’s Solid Waste Services two brush and yard trimmings collection facilities. Yard trimmings are collected curbside on a quarterly basis from the City’s solid waste customers and taken to one of the two collection centers where they are processed by City staff and equipment. These sites are open to residential and commercial customers year round. TDS also accepts brush at the Martinez II facility and periodically brings in a Diamond Z tub grinder to process those materials.
The Martinez facility is open to other public agencies, as well as local landscapers and the general public for recycling compostable materials at competitive tipping fees. SARA pays $22/wet ton for biosolids management. Retail and wholesale customers can purchase compost, mulch and soils from the facility in bulk.
TDS routinely transports compostable materials to the site from its many recycling customers located in the San Antonio region. Food waste comes from local schools as well as a company that processes “ready-to-eat” packaged fruits and vegetables distributed to regional grocery stores. It is composted in windrows separate from those processing biosolids, thereby offering compost customers a variety of products to purchase.
The biosolids compost products are typically marketed for use on lawns and landscapes (under the brand “Elite Lawn”) or are blended into other landscaping products. The non-biosolids compost product (“Eco Thrive”) is marketed for use in vegetable gardens and is blended into gardening soils.
In addition to monthly revenue for lease of the site, and reduced disposal costs, SARA receives royalties from tipping revenues and compost sales, and sale of recycled water, commercial wastewater service, and laboratory analysis to TDS. TDS provides SARA with complimentary compost and native trees that will be grown on-site using compost and recycled water from SARA’s wastewater plant. These trees will be planted at its many parks, hike and bike trails, and administrative offices.
Construction of new buildings by TDS (with review and approval from SARA) is underway, including a bagging facility and operations center. They are scheduled to be complete in mid-2016. The Martinez II facility has effectively converted a past biosolids disposal problem into a long-term asset that benefits SARA, TDS and the general public.
Jim Doersam, P.E., is a Senior Engineer with the San Antonio River Authority. Paul Gregory is Director of Recycling at Texas Disposal Systems, Inc./Texas Landfill Management, LLC.