Inspire : Public Works May Jun 2013
24 Public Works Professional May-June 2013 ORIGINAL STP NEW STP CAPACITY 4000 equivalent people 9250 equivalent people TREATMENT PROCESS Trickling lter Oxidation ditch TREATMENT STANDARD Ammonia 25 mg/L Ammonia 1 mg/L Total Nitrogen 30 mg/L Total Nitrogen 3 mg/L Total Phosphorus 5 mg/L Total Phosphorus 0.3 mg/L F. Coliform 1000cfu/100 mL Enterococci 40cfu/100 mL ODOUR CONTROL Nil Biological & carbon lters PLANT SPECIFICATIONS INNOVATIVE TIME & COST SAVINGS To get competitive tenders and cost savings, Unitywater bundled the Cooroy project with another STP upgrade at Woodford (60km south) via a procurement model of Early Contractor Involvement (ECI). They used the ECI process to revise design criteria of the original plants to seek additional upgrade innovations and invited expressions of interest to construct both projects. The intention was to have experienced contractors provide input into the design process. Once the ECI phase was completed, participants were asked to submit individual tenders for each project on the same optimised design for each plant. They were also required to submit a separate tender and discounted price in the event that they were awarded both projects. Monadelphous Engineering gained the construction tender for both upgrades, producing signifcant savings. Work began on the Cooroy upgrade in November 2011 and was completed in January 2013. (Montgomery Watson & Harza did the design.) ENVIRONMENTAL SOLUTIONS To reduce capital/operating costs and deliver environmentally sustainable services, Unitywater uses wetland processes for natural treatment at its plants in Cooroy, Kenilworth, Maleny and Coolum. The upgraded Cooroy STP has to meet stringent effluent requirements, including a high level of nutrient removal and no nuisance odours. Effluent from the upgraded plant will discharge to Cooroy Creek via an existing wetlands system. The wetlands further polish effluent from the existing process, removing nitrogen and phosphorus and reducing impact on receiving waters. Odour emissions are targeted by covering tanks and installing the latest odour control technology. CONNECTING AND PROTECTING The upgraded Cooroy STP caters for population predictions to 2026 and also enables many properties in nearby Pomona to connect to the sewerage network for the rst time. Some 120 Pomona properties with failing septic systems were able to connect to the network in 2012 before completion of the upgrade, and an additional 274 will now be invited to connect. ENVIRONMENTAL CONSIDERATIONS During the upgrade, a small area of non-remnant vegetation near the existing plant was cleared and fenced with Council approval. Care was taken to protect the environment and a wildlife expert was on site to ensure no native animals were harmed. In addition, woodchips from the cleared vegetation was re-used on site, so nothing went to waste. ••• MEETING THE NEED We operate and maintain more pipes, pumps and treatment plants per person than a typical urbanised water supply and sewerage business.
Public Works Mar Apr 2013
Public Works July Aug 2013