Mbnru: Progressive Safety In Design – Concept Design Through Design Build

An intentional culture of continuing safety in design has shaped the success of the largest wastewater treatment plant (WWTP) constructed in New Zealand in the last 15 years. Commencing in 2013, safe operation was at the forefront during design development and was the focus during construction. The collaborative approach between Watercare’s Operation and Maintenance team and CH2M Beca designers set the stage for success which was progressively expanded through the next stage of the resulting design build construction contract. The culmination of these efforts was a safer construction and operational environment for many years to come.

Designed by CH2M Beca and constructed by a McConnell Dowell - HEB Joint Venture (JV), the new $140M Biological Nutrient Removal (BNR) upgrade to Watercare's Mangere WWTP will add capacity for an additional 250,000 people, meeting Auckland's projected growth and improving the water quality discharged to the Manukau Harbour.

The resulting construction contract contained a nested structural design-build component. Once the project had progressed to tender phase it was paramount that the communication and protection of Safety In Design (SID) functionality within the Principals’ requirements related to these elements was maintained, and where possible, improved. Within the contract Watercare included workshops with CH2M Beca and the JV structural designer – Holmes Engineering – to continue the collaborative working approach to reduce risk and improve safety. As a result of the reviews and SID sessions, several key elements were included that not only improved the long term operational safety, but also improved safety from a construction perspective. This involved items such as access doors through external walls at base and ground levels, and internal access ways through long baffles to facilitate safer access for people and equipment.

JV led the construction phase from June 2015 to October 2017, engaging over 2000 staff on site. Throughout this phase Watercare, CH2M Beca and JV’s progressive approach to maximizing construction and long term operational safety continued. As a result, several improvements to both the safety during construction as well as operation were achieved during this stage.

The commissioning phase was completed in March 2018. As part of Watercare’s procedures and its emphasis on safety reviews, the Watercare Health and Safety team gave continual inputs during the construction phase and provided the final sign-offs prior to takeover.

This paper will discuss the collaborative safety in design approach, contracting approach and the breakdown of traditional barriers, from concept design through the six major phases to operational handover.