The IPWEA Australasia Excellence Awards were held on 23 August, at the 2017 IPWEA International Public Works Conference held in Perth. Judged by a panel of industry experts, the finalists represented the industry’s best of the best, having already won their category from each Australian state and New Zealand in 2015-2017.
The award for the Best Public Works Project 2017 Under $2m went to the Sumner Road Retaining Wall, Stage 4 project. Fulton Hogan delivered this project as part of the Stronger Christchurch Infrastructure Rebuild Team (SCIRT).
Fulton Hogan’s rebuild team set up a separate site office in the harbour suburb of Lyttelton, and for almost five years Fulton Hogan employees became Lyttelton locals while they repaired and rebuilt 43 retaining walls.
Stage 4 of this project was the re-strengthening of an existing retaining wall that supports Sumner Road above the Holcim Cement site. The retaining wall consisted of three existing 100 year old stone walls up to 6 meters high and the site was steep, narrow, unstable and difficult to access.
The design called for 180 new soil nails to be drilled through the existing block and grouted into place up to 8 meters long and 180mm in diameter. Once the soil nails were completed, drainage was installed, a footing was dug and poured and a reinforced shotcrete facing was applied in two layers of 150mm. A new handrail and repairs to damaged kerb and channel and footpath completed the project.
The construction methodology needed to ensure that each construction step did not put undue loading on the wall and cause a catastrophic failure. Drilling the soil nails from a crane lifted work access platform was determined to be the safest and most cost effective way of installing the nails. This is because no additional load would be exerted on the existing wall or downhill slope, until nails were installed in the wall.
Project Manager David Oliver said, “This method was chosen because the crane would sit back from the edge of the existing wall without placing any additional weight on the damaged retaining wall that could cause it to fail. The platform gave the guys an area to work and safely operate the drilling machinery. As some of the soil nails took up to nine hours to drill and install, it was important that the guys had an adequate working environment.”
Fulton Hogan’s delivery team were involved from the design phase through to the delivery of the project, and our workers became very close neighbours to the residents in Cunningham Terrace and Sumner Road with many of our workers going the extra mile for the residents: building access steps, moving rubbish bins and carrying groceries within the road closure area.
To help build a relationship with locals, the Fulton Hogan team did a kindergarten and a school visit, and held open days on site to allow the community to see progress, and get more of an understanding of the work involved in this project. The team encouraged residents and the community to pop in to the site office if they had any questions or concerns about the work, and a free 0800 number and email address were also available for project queries.
“It was a challenging job, but also a satisfying one. We managed to finish ahead of time because of the supportive residents. They really understood the site constraints and the difficult access. Because of their co-operation, residents now have a number of freshly-repaired concrete retaining walls to help keep their roads in place and enable homes to be rebuilt”, said David.
The project was completed ahead of schedule, under budget and achieved zero harm on 99.32% of the construction days.