Customer: Watercare Services Ltd Contract: Design & Construct Location: Warkworth, Auckland

Fast Facts New 247 litres/sec pump station Above and below-ground structures Part of a broader wastewater scheme delivered by McConnell Dowell

McConnell Dowell (MCD) was awarded the design and construct contract for the Warkworth Pump Station, part of Watercare's broader scheme, to improve the wastewater network from Warkworth to Snells Beach.

The North East Wastewater Servicing Scheme will cater for future growth and enable Watercare to decommission the existing Warkworth Wastewater Treatment Plant which discharges into the Mahurangi River. The scheme comprises a pump station, associated rising mains and a gravity sewer that will terminate at the new Snells Beach Wastewater Treatment Plant (WWTP). 

The scope of work to construct the new 247 l/s, wet well/dry well Wastewater Pump Station adjacent to the existing Lilburn Street Pump Station in Lucy Moore Memorial Park included:

• an above-ground structure 4.4 m high, 9.2 m long and 4 m wide
• structures approximately 12 m below ground including an inlet chamber, gantry crane, drywell, wet well and emergency storage 
• an overflow pipe from the pump station to the existing stormwater pond 
• ancillary above-ground structures, including an odour control (biofilter), standby generator, transformer, flowmeter chamber, welfare facilities; and 
• an access road and carpark 

The challenge  

The Warkworth pump station site is located within Lucy Moore Memorial Park, adjacent to the Mahurangi River. The park is an open green space that contains walking tracks, a skate ramp and a flying fox. The park is a popular community amenity and provides a thoroughfare to the town centre. 

Lucy Moore Memorial Park is named after one of Warkworth’s own homegrown heroes. Lucy Moore earned the moniker, ‘mother of New Zealand botany’, receiving national and international recognition for her achievements in botany. 

The solution:  

The pump station and storage tank were constructed using an innovative caisson (sunk shaft) construction method which provided the following benefits:  

• Reduced construction footprint due to a reduction in the working space  
• Less noise and vibration impact because there is no significant backfilling required 
• Minimised time required on-site, which further reduces overall community impact 
• Enhanced safety for site workers and park users 

The key to success

The construction methodology was developed with input from specialists and experts to comply with statutory, contractual and consent requirements. This included the development of environmental controls to protect the sensitive park and river environment, engaging an arborist to identify and protect trees and vegetation, iwi consultation, and a strategy for effective stakeholder management of impacted residents and the community.  

Check out the project's wrap-up video below!