Tasman District Flood Recovery

Location: Tasman District, New Zealand

Region: Asia Pacific

Service Offering: Engineering & Design, Environmental Planning & Management, Sustainability & Climate Change, Construction & Construction Management

Market Sector: Water & Wastewater, Transportation

Status: Complete

On December 15, 2011, Nelson was hit by a devastating 1 in 500 year flood. Record high rainfall caused extensive land slips across the district taking out roads, houses and infrastructure and adding huge sediment loads into the swollen rivers and streams. This was exacerbated by the flood debris created by slips and bank erosion and carried by the flood waters. New Zealand’s Ministry of Civil Defence declared a state of emergency over both Tasman District Council and Nelson City Council with a joint population around 87,000 people.

During this state of emergency, a team of MWH geotechnical and infrastructure engineers helped New Zealand’s Civil Defense by undertaking public health and safety assessments and coordinating the flood response to Tasman District Council’s roading and utilities contractors.

Once the rain abated, the team assisted Council to coordinate and undertake the initial recovery operations, inspecting damaged assets, directing works required to open roads and restore essential services. This involved assessing multiple slip and inundation sites and directing contractors to clear slip and flood debris material to provide access to properties, restoring water and wastewater services where necessary and making alternative arrangements where the damage was too extensive. The priority was to make things safe for Christmas.

Through the Christmas break the already damaged region was hit by another severe rainfall event causing further extensive damage and extending the state of emergency. MWH continued to coordinate and manage the flood response and service recovery.

In the new year, the flood recovery began in earnest. Tasman District Council commissioned MWH to undertake the engineering for the flood repairs which included:

• Preparing, in coordination with Council, of an extensive flood damage list.
• Planning and managing the implementation of damage site and repair option assessments.
• Preparing damage repair cost estimates and programs.
• Implementing the design, procurement and construction monitoring of damage repairs.
• Collating and developing flood damage cost databases to provide for insurance claims.

The MWH team has been acclaimed by Tasman District Council for the speed of its response and the skill and expertise displayed during a fraught emergency scenario.