Napier's Cross Country Drain - A Smart Stormwater Asset

The Napier Cross Country Drain was designed to future-proof the drainage of suburban Napier. The scheme was conceived in 1995 and a discharge consent for 20 m3 /s capacity and land designations over the full length were granted in the late 1990s.

The underlying principle is to capture runoff from areas south of Napier City, and divert them directly to a coastal outfall, rather than have them flowing through low-lying residential areas. This frees up existing urban capacity for future infill development. It also provides an alternate discharge, increasing system robustness.

The scheme consists of a 4.3km drain with a 10m3 /s pump station (with provision for future upgrade). The pump station has three main pumps, with a fourth smaller (250L/s) pump for low flows.

Three 230m rising mains discharge onto Awatoto beach via a unique outfall comprising three architecturally designed “pods” within a wide shallow basin along the beachfront, to disperse water across the stony beach.

Power is provided to the main pumps by three dedicated diesel generators, which was more cost effective than supplying power from the main grid and removed the risk from major mains power outage during severe storms.