Dalrymple Bay Coal Terminal Pty Ltd (DBCT P/L) and Dalrymple Bay Coal Terminal Management (DBCTM) are undertaking a Water Quality Improvement Project (WQIP) to reduce the likelihood of non-compliant stormwater discharges from the Dalrymple Bay Coal Terminal (DBCT) Industrial Dam (ID). $61.429 million worth of capital and operational costs have been allocated to the project.
Part of DBCT P/L’s environmental licence to operate the terminal includes water management. While every effort is made to harvest and recycle water onsite for dust suppression purposes, our licence also allows us to discharge excess water into Sandfly Creek but with strict controls on the amount of coal fines, or Total Suspended Solids (TSS), in the water.
The ID collects all recycled operational water and stormwater run-off from the stockyard and out-loading conveyor systems, which contains a high proportion of coal fines. In recent wet seasons high rainfall has caused uncontrolled discharges from the ID to Sandfly Creek, which have contained TSS that exceeded allowable release limits. The DBCTM and DBCT P/L Boards identified WQIP as a project requiring immediate attention. The WQIP investigated all possible opportunities to minimise the likelihood of future discharge exceedances from the ID during wet season stormwater events.
Phase 1 included concept development and scope definition for 18 short-listed capital improvement sub-projects that showed a significant contribution to reducing the likelihood of exceedances from the ID. A number of targeted recommendations have been identified for implementation in Phase 2 and Phase 3 of the project.
From undertaking these improvement projects, the Water Management Committee is now able to undertake more regular controlled discharges from the Quarry Dam (QD) into Sandfly Creek in a manner that meets our environmental licence conditions.
DBCTM has recently completed Phase 2 of the project which included the following works;
- Replacing the ID WM3 pumps with three new high capacity transfer pumps, Sub 3B electrical upgrade and new 800mm poly pipeline from ID to QD. The ID to QD transfer rate is now approx. 1150 L/S with all three pumps running.
- Expansion of the existing ID coal recovery infrastructure including new drying slabs for the ID pits, new concrete channel and causeway, new containment cells in the floor of the ID, new pump sump filter fence barrier and ID spillway raise of 375mm.
- Upgrade of the existing coal collection pit in south end of Row 1 (Pit 1/A).
- Portable flocculant dosing plant.
Phase 3 Update
Phase 3 of the WQIP has been approved to proceed and will be substantially complete by the end of 2015. The Phase 3 scope includes the following main elements;
- Construction of new 640ML Rail Loop Dam (RLD) and diversion of Grendon Creek inside the DBCT rail loop.
- Raising of existing QD wall by 5m to gain approx. 180ML additional storage.
- New DN800 poly pipeline from QD to RLD to take QD overflow.
- Return pumps & valving to transfer water from RLD back up the pipeline to the QD in the dry season for dust suppression purposes.
- New 2ML WM1 storage tank and pumpset next to existing 100KL tank.
- New floc plant at ID pit entry to treat incoming ID stormwater flows.
- Diversion of stormwater from areas west of DBCT stockyard to reduce ID catchment area.
The new RLD and QD raising is the most significant contract package within the Phase 3 scope, and these two elements have been consolidated into one civil contract starting onsite in March this year. The site plan below shows the location of the RLD and Grendon Creek diversion.
Representatives from the Community Working Group were hosted on site in January to tour the Phase 2 completed works and see the location for the RLD.