Strowan Fields 3 & 4 - Civil Drainage work

SCOPE:

Project Overview: Strowen Fields is a greenfields site that is being developed for residential subdivision comprising of 550 lots. Strowen Fields is on the Eastern town boundary of Ashburton and is on heavy soils with natural springs that drain into overland streams.

INSTALL:

Comprised of 2950m of PVC Sewer Pipe ranging from 100mm to 300mm, 790m of RCRRJ Class 4 Concrete Stormwater pipe ranging from 300mm to 600mm. Installation of 19 Single back entry sumps, 11 double back entry sumps, 54 manholes varying in size from 1050mm to 1800mm, 2350m of kerb prep.

DEEP EXCAVATIONS:

This included 800m of sewer pipe installation was carried out at depths around 4m. Grant Hood Contracting used 2 methods to install at this depth, trench shields were used where space was tight and access was limited. Open cut trenches were also used where possible, this method was by far the best option for productivity, safety and staff morale. Considering the depths, ground conditions and carrying this work out in winter we are extremely proud that no staff were injured and there wellbeing remained high throughout the project.

DEWATERING:

Strowen Fields location is in a very high water table zone and pezo readings taken throughout the works had static water levels at 1.15m for large parts of the project. This posed significant environmental risks as well as safety risks, Grant Hood Contracting managed these risks throughout the project to ensure no compliance issues arose. At the peak of dewatering we were pumping 300 litres per second 24/7, this was all carried out in house with our two 6 inch and two 8 inch pumps. 

RESOURCES:

• Excavators 13T-30T
• 6T Dozer
• ADT
• x2 6” Pumps
• x2 8”Pumps
• Loader

TIMELINESS:

This project was under tight timeframes due to ECAN consent delays during the design period and was at risk of losing significant sales due to the sunset clause. Grant Hood was proud to deliver this project in on time and on budget. 

ENVIRONMENT:

High water table was a huge issue from the enviornment and ECAN was involved.