Protecting Richmond Town Centre

Richmond town centre lies at the confluence of two stormwater catchments. While there are detention dams upstream designed to protect the town centre, the stormwater systems do not meet the current desired levels of service and the town centre experiences periodic flooding episodes.

Tasman District Council have long known of the need to upgrade the stormwater systems, and amidst strong competition for stormwater funding, it has planned to upgrade the stormwater system in the town centre in 2016/17. A severe (1 in 500 year) event in April 2013 caused widespread flooding in the town centre which re-focused the community and the Council on the stormwater deficiencies and reinforced the priority to upgrade.

In addition to the capacity drivers, there are a number of related matters that Council need to consider, including:

• The main 900mm pipe in the main street (Queen Street) has significant condition issues which cannot be left.
• If the main street is to be trenched to relay large diameter pipes, Council want to use that opportunity to reinstate the main street in a manner that improves the streetscape in alignment with an overall town centre framework.
• The benefit of adopting a resilient stormwater strategy. The strategy accepts that primary drainage systems do not always function perfectly and that overland flow will occur at some time. A resilient stormwater strategy will anticipate this and still manage floods in the catchment.

This paper summarises the immediate situation facing the town centre and the challenges that the project team encountered in developing a resilient strategy.