The City Rail Link is the largest transport infrastructure project ever to be undertaken in New Zealand. The project comprises the construction of a 3.4 km underground passenger railway and includes two new underground stations at Te Waihorotiu and Karanga-a-Hape and a redeveloped Maungawhau Station.

The CRL project is committed to meeting its compliance obligations and taking responsibility for preventing and managing risks to the environment and local communities. One of the key environmental risk areas that is carefully managed throughout construction is the treatment of stormwater runoff from construction areas and water generated from construction activities, which can be sediment-laden and highly alkaline. The water must be treated to meet the required water quality discharge standards before being discharged to the stormwater or wastewater network. This has largely been achieved through the use of automated dosing water treatment systems, as the location of the construction sites in Auckland's CBD did not allow for the use of more traditional sediment retention ponds typically seen on earthworks sites. 

The Project specified water treatment systems that included continuous monitoring of water quality parameters thus enabling full transparency of compliance with the Project's discharge standards. However, this relatively new technology hasn't come without its own set of limitations that has required an adaptive management approach from the construction team.  This presentation will discuss some of the challenges faced from the contractor's perspective in working to achieve continuous compliance with the discharge permit consent conditions and ensuring the protection of our waterways.

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