Four years of research have been carried out to find the best sewage system for the city's future.

The Council wants to ensure that the water used in the system is treated to the degree that discharge into the environment has such a low impact that the method of discharge becomes a "relatively minor consideration".

Preliminary recommendations were made by the Wastewater Working Party in 1998.

Since then, extensive studies have refined the research to come down to two Council options:

• Continuing with the present arrangement of discharge into the Avon-Heathcote Estuary/ Ihutai
• Building a new pipe out to sea.

Both would include a substantial upgrade in the present quality of treatment.

As a solution for the next 15 years, the Council favours continuing with an estuary discharge, in conjunction with a range of treatment quality improvements and a new Green Edge scheme.

The Green Edge concept would see redevelopment of the land stretching from Bexley Road in the north to Ferrymead Bridge and eventually beyond to include Travis Swamp and a green corridor extending as far north as Brooklands.

This would be done to create what has been described as an ecological wonder - a recreational facility, unparalleled anywhere. It would be as significant as the establishment of Hagley Park and the Botanic Gardens.

The area will include recreation areas, a system of ponds containing special areas for pied stilts and other waders, such as pukeko.

Various environments could be created such as wetlands, shrubland, and coastal forest. Other uses could be biking, horse riding, eco- tourism and walking.

Work will be carried out with the natural systems of the area and the needs of wildlife. The Council will work to find a solution that will meet the wildlife, aesthetic and landscaping requirements.

The chance to develop the Green Edge scheme, along with an outlet pipe, arises because the City Council wastewater disposal consent ends in October next year.

A $33 million expansion of the Council's wastewater treatment plant at Bromley is already under way (see the August issue of Christchurch City Scene).