Upgrades of this nature can have several challenges that can impact the design, program, and project cost. Identifying them early enabled a timely and strategic approach to overcome them. One of the major challenges on this project was some of the unknowns, mostly relating to the historical data and missing as-built information. 

PST 1 Challenges:

• The capacity and suitability of the PST 1 centre column’s existing support structure to be reused, to support the new clarifier mechanism, was unknown. To overcome this, Jaydo carried out a detailed investigation and condition assessment of the support structure involving emptying and cleaning out the tank, getting access into the tank and getting detailed measurements and condition assessment of each member of the support structure. The information collected was then assessed and a suitable cost-effective modification was proposed to the client who was happy accept and implement. Jaydo carried out the required strengthening of the support structure, that enabled use of the existing support with the new clarifier.
• PST 1 floor condition: during a detailed investigation it was discovered that the existing floor coating was delaminating, uneven, and scraped off in certain areas. This was relayed to the client as part of the condition assessment report, and in collaboration with the client, a further detailed assessment with cored holes was carried out. Based on the findings, and in consultation with specialist coating contractor, a proposed solution for recoating the tank floor was accepted by the client.

PST 2 Challenges:

• PST 2’s centre column base was encased in concrete, and the depth and connection details on the column bottom flange was unknown. Jaydo carried out a preliminary investigation to determine the depth of cover, however, the design of the new clarifier equipment could not be completed with the missing information. Jaydo staged the design and fabrication process where we completed the design and fabrication of the remaining items except the bottom flange arrangement of the centre column. Demolition of the concrete cover over the column base was prioritised during decommissioning, to obtain the required details, and the centre column was fabricated while site works progressed including demolition and assembly of the rest of the clarifier bridge.
• Program challenge: the Lakes Entrance WWTP has a unique loading pattern where the traditional dry season over summer is when it has the high inflow, so both PST 1 &2 had to be available and operational prior to summer, with the works staggered to have one PST completed before summer and the second one taken out after Easter long weekend the following year. Jaydo’s thorough planning of the works in consultation with the client and site operators, and collaboration with the clarifier supplier, enabled an enhanced staged delivery of the projects. Fabrication and delivery of the bridge was completed and delivered to site early to enable assembly of majority of the bridge, prior to decommissioning and demolition works to conform missing information from site. Learnings from the first PST upgrade were also acknowledged and implemented on the PST 2 delivery. This enabled completion of both PST upgrades ahead of schedule and both systems operational ahead of the peak summer season.