BlueLine Drains undertook a significant project for the Wellington Transport Alliance (WTA), focusing on the maintenance and inspections of stormwater culverts along State Highways 1 and 2 in the Wellington and Wairarapa regions. This initiative was part of an eleven-year collaboration involving Waka Kotahi (NZTA), WSP New Zealand, and Fulton Hogan, aimed at maintaining the state highway network assets.
Project Scope:
The project encompassed the identification, location, thorough cleaning and detailed condition assessment of 56 stormwater culverts classified across varying priorities. These culverts, located between Tawa and Ngauranga on State Highway 1, and between Featherston and Masterton on State Highway 2, were inspected following the New Zealand Gravity Pipe Inspection Manual guidelines, modified to suit specific WTA requirements.
Project Timeline:
The project was conducted from 12 May 2024, to 25 June 2024, spanning 15 shifts, including 13 night shifts and 2 day shifts, with some additional disruptions due to traffic management issues.
Resources Utilised:
- Human Resources: Qualified Operators & Supervisors.
- Equipment: Combination Truck, CCTV Van, Utility Vehicle, Confined Space Equipment, Fall Arrest Systems, and Specialised Tools.
- Materials: Silt Fences, Pneumatic Pipe Plugs, and Waste Disposal Services.
Methodology:
The project required an adaptive approach due to the variability in culvert conditions and access challenges. Techniques included Hydro Excavation, Jetting & Suction, and advanced CCTV Inspections. The team also navigated complex terrain using Fall Arrest Systems to access difficult culvert locations.
Key Findings:
- Culvert Conditions: Varied significantly with some completely blocked requiring extensive cleaning.
- Asset Database: Many culverts were inaccurately recorded in the WTA database; these were updated throughout the project.
- Debris Removal: A total of 37.5 cubic meters of dewatered solid debris was removed and properly disposed of.
Challenges & Solutions:
- Access & Safety: High-risk environments due to the steep, uneven terrain and highway settings. Utilised specialised equipment and rigorous safety protocols.
- Data Inaccuracies: Discrepancies in existing asset data were addressed through thorough onsite inspections and cross-referencing multiple data sources.
- Traffic Management: Coordination with WTA’s traffic management teams to minimise commuter disruption was critical, requiring flexible scheduling and clear communication.
Conclusions & Recommendations:
The project successfully updated and corrected the asset database for WTA, providing a clear understanding of the condition and specifications of each culvert. This will aid in future maintenance planning and risk management. Recommendations include ongoing monitoring of culvert conditions and the use of similar comprehensive assessment techniques for other infrastructure assets.
Client Testimonial:
Mike Tatam, Planning & Programme Lead at Wellington Transport Alliance, commended BlueLine Drains for our professionalism and the accuracy of the project deliverables, highlighting the effective communication and budget management throughout the project.
“Using BlueLine Drains for recent culvert inspections has been a fantastic choice. We received comprehensive daily updates from Daniel clarifying what the team accomplished each shift along with a rolling cost summary so the budget could be easily managed and accurate along the way. The team faced some challenging locations, but everything was tackled with professionalism and competence. We now have updated, and accurate records of each asset allocated and can plan any follow up works as required. Would highly recommend.”
Further Information:
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