InfoWorks WS models water supply extension project in Rotorua, New Zealand

Urban growth can place many stresses on a water supply system that has been designed to service smaller demands. Population growth is inevitable, and Local Authorities are continually trying to make the management of a constantly changing system as simple as possible. In addition, developers often want subdivisions in areas where infrastructure is unable to cope, such as at extremities of the system and in areas of high elevation.

A significant issue facing many Local Authorities is the potential to combine existing rural water supplies together, or to extend urban supplies into rural areas. This article examines the options available to the Rotorua District Council to extend their Eastern Water Supply Area out to Otaramarae.

Considerations included the installation of additional trunk main and reservoir storage for the transfer of water to the proposed extensions. A number of scenarios were modelled using InfoWorks WS to ascertain the size and route of the trunk mains and required storage for the rural areas on the route. Short term and long term options were investigated.

InfoWorks WS was also utilised in the identification and evaluation of appropriate sites for the location of an additional service reservoir to adequately service the demand from the forecasted growth. A number of scenarios were analysed for four potential reservoir sites at different contour levels. A significant number of considerations needed to be taken into account to ensure the optimum solution was reached to allow the operation of the system to be as straightforward, yet as cost effective, as possible, whilst still servicing all customers at appropriate service levels.

Authors: Louise Lindsay and Jeff Booth of Jeff Booth Consulting Ltd, New Zealand.

The complete article may be downloaded below. It first appeared as a paper at the NZWWA’s 50th Anniversary Conference and Expo - Ensuring Water for Our Future, held in Christchurch, September 2008.

• Full Article - Modeling options to extend the Eastern Water Supply infrastructure. (695KB)