4 Emirau Place, Glenfield – 5-Lot Residential Subdivision

Public Stormwater

We relayed approximately 25 metres of existing 375mm Class 4 RRJ reinforced concrete stormwater pipe, connecting from boundary to boundary.

The works also included a 150mm saddle connection and one stormwater manhole.

Public Wastewater

Our team completed the wastewater drainage works, including the construction of four wastewater manholes and the associated pipework and connections required for the development.

Across both systems, the project included a total of five manholes: four wastewater manholes and one stormwater manhole.

The most difficult part of the project was the replacement of the 375mm stormwater pipe in a trench approaching five metres deep.

The site had a steep slope, with bushland below the work area. The soil was extremely soft and unstable, and the trench repeatedly collapsed during excavation. The excavation was also very close to a neighbouring property's existing foundation, requiring careful control of the work area and construction sequence.

These conditions made it impractical to open the entire pipe alignment at once.

We progressed the stormwater pipe replacement in short sections. After installing each section of pipe, we backfilled it before moving forward to the next section.

This staged approach limited the length of open trench and allowed our team to respond to the unstable ground conditions as work progressed.

The approximately 25-metre stormwater pipe replacement took close to two weeks to complete. Careful coordination between thApproach

e excavator operator and ground crew was essential throughout the excavation, pipe installation and backfilling stages.

Work commenced in mid-to-late September 2026, and the overall project was completed over approximately three weeks.

The completed scope included the 375mm stormwater pipe replacement, the 150mm saddle connection, one stormwater manhole and four wastewater manholes.

This project required practical site judgement, controlled excavation and a carefully managed installation sequence to deliver drainage infrastructure under challenging ground conditions.

C&B Drainage Contracting Ltd
Public Stormwater & Wastewater | Subdivision Drainage | Civil Drainage | Auckland