Yeppoon Sewage Treatment Plant Augmentation Project

Abstract

The existing Yeppoon Sewage Treatment Plant (YSTP) was commissioned in 2005 as a BNR (Biological Nutrient Removal) plant designed to treat flow from a population of 21,000 equivalent persons (EP). The treated effluent from the plant discharged to nearby storage dams and was either reused for irrigation or discharged to the adjacent Corduroy Creek. Sludge produced by the treatment process was dewatered prior to disposal off-site at the neighbouring landfill. An audit of the YSTP undertaken in 2016 identified that the plant was nearing design capacity and that an upgrade to the plant was required. The first stage augmentation adopted by Council involved increasing the capacity to 31,000 EP and converting the plant to an MBR (Membrane Bio-Reactor) treatment process. The preliminary project cost estimate was $15M, with Council successfully obtaining $5M in funding from the State Government’s Building Our Regions (BOR) program. Council determined that the most suitable project delivery methodology was a Design and Construct (D&C) contract, and this was procured through a two-phase tender process – Expressions of Interest (EOI) from the market, followed by an Invitation to Tender (ITT) to the shortlisted D&C Contractors. The contract for the design and construction of the Yeppoon STP augmentation was awarded to Downer Utilities in March 2018. The assessment of tenders was based on up-front capital cost and forecast operation and maintenance costs. Consideration was also given to the extent of disruption to the operating plant during construction. The scope of work undertaken was: - Provision of a new inlet works, including odour control - Upgrade of the diffused aeration system in the existing bioreactors - Provision of an ultrafiltration membrane system to separate the biological solids and the treated effluent - A sludge dewatering centrifuge to replace the ageing belt filter press, and - Chemical dosing facilities for pH correction and membrane cleaning - Electrical, instrumentation & control installation including 8 shutdowns for integration The construction work commenced on site in July 2018 and Practical Completion was achieved on 12th August 2019. The construction was achieved with very few shutdowns and minimal disruptions to plant treatment and effluent quality. A 28 day performance guarantee testing period confirmed that the finished plant produced the requisite effluent quality, whilst achieving reductions in power and chemical dosing costs, as guaranteed at the time of tender. The effluent produced to date is Class A recycled water and is being discharged to Council’s recycled water system.