Water Journal : Current Feb 2016
www.awa.asn.au 67 Examples included: l Acceptance that specifications were achievable using existing assets; l Refurbishment and reuse of available equipment; l Rebuilding civil works utilising existing foundations; l Demonstrating that treatment risks were insignificant, avoiding major capital upgrades. Challenges to construction methodologies and DCWW specifications resulted in cost reductions, such as: l DCWW specification challenge: Resizing pipework at Gowerton WWTW, minimal velocities need not apply to final effluent pipework, as risks of encountering settleable solids were remote (pipework replacement avoided). l DCWW specification challenge – tank level detection: DCWW had specified that chemical storage tanks required level probes to mitigate risks of spillage. Upon review DCWW accepted mitigation using low-level pressure transducers, avoiding significant costs of fixed access to the top of tanks for maintenance of probes. l Construction methodologies: Use of pre-cast and pre-fabricated units Adoption of pre-cast concrete and pre-fabricated plastics components had cost, program and safety benefits. The main challenges were accommodating plant upgrades within heavily congested works sites that had previously undergone several rounds of upgrade works. Factors involved included: l Maintaining clearances to and protection of physical assets, both DCWW’s and that of other service providers; l Managing complex works within restricted spaces; l Ensuring building and plant locations allowed for vehicle turning circles; l Interconnections between new works and existing process units; and l Maintaining normal plant operations while implementing the upgrades. Detailed examples of challenges faced at the sites are described in the main paper. Implementation of chemical dosing for P Removal at these four heavily congested WWTW sites provided significant challenges for budget management and working constraints. However, with focused and collaborative stakeholders, environmental compliance was achieved by the target (31 March 2015). The P trends following chemical dosing for one of the sites are displayed in the graph on the left. To read the full article, visit the Water e-Journal at bit.ly/e-Journal The main challenges were accommodating plant upgrades within heavily congested works sites that had previously undergone several rounds of upgrade works.
Water Journal November 2015
Current May 2016