Lincoln’s sewerage plant deteriorating, hearing told

Press, 13 October 1983, Page 14

Lincoln’s sewerage plant deteriorating, hearing told

Lincoln’s sewage treatment plant is deteriorating and cannot handle present loads, a water rights application hearing was told in Christchurch yesterday.

The Ellesmere County Council has applied to a North Canterbury Catchment Board and Regional Water Board’s standing tribunal to discharge a maximum of 1700 cubic metres of treated sewage effluent from a primary oxidation pond at the rate of 20 litres a second to the L2 River.

The tribunal comprised Messrs 0. J. Osborne (chairman), J. W. Levy, and F. F. Wilding. “This system was initially intended for a designed population of 2500 but due to the locality it serves its requirements vary substantially throughout a year,” the hearing was told.

The present plant was required to deal with sewage from Lincoln township, Lincoln College, the secondary and primary schools, and Government research organisations.

“Even if the present plant was upgraded, it would be unable to handle the future loadings and would be at its maximum capacity within 10 years at which stage the situation would exist as at present,” the hearing was

told. The Ellesmere County believes an oxidation pond is ideally suited for small and medium-sized communities, requires low maintenance, is not dependant on trained and qualified operators, and can be easily expanded if required. The Ellesmere County Council also contends that any discharge from the oxidation pond would have a minimal effect on the river and cause an insignificant increase in nutrients flowing into Lake Ellesmere.

Mr B. F. Webb, secretary of the North Canterbury Acclimatisation Society, believed the water right should be refused until a more environmentally acceptable treatment and disposal system was devised. Mr Webb said that the society believed that the effluent, once properly and reasonably treated, should be disposed of partly or totally by land irrigation either using a certain quantity each day to level out any influx peak loads, or being utilised over a suitable period when the underground aquifer is low. “Under this disposal suggestion, direct discharge into the L2 would be in an emergency when the water table was too high or quantity of effluent too great

at any one time,” he said.

Lower Selwyn Hut owners object to the application because any discharge should be further treated to filter out algae and remove harmful ingredients such as coliform bacteria before it is allowed to be discharged into Lake Ellesmere. “We feel that there are many other means of handling the treatment of sewage and finally disposing of it other than by what is possibly one on the easiest and cheapest ways which includes running the end product down a natural waterway and into a lake of international importance as a wetlands,” their submissions said. The hut owners were worried that Lake Ellesmere was turning into a polluted puddle with a rapid decrease in the number and quality of trout. The Royal Forest and Bird Protection Society also objected to the water application, saying that nothing should be done to aggravate the nutrient level of the lake which is in excess of those normally expected.

Mr I. W. Lineham, an investigating officer with the Catchment Board, said that the lake was badly overloaded with nutrients at present, but that the granting of this right would only

slightly increase these levels. “The contribution of nutrients to the lake from the proposed waste discharge is small compared with that from agricultural use of the lake catchment.

“However, reduction in nutrient content where practical, namely from the applicant’s proposed effluent discharge and agricultural point discharges, would have an appreciable effect upon the lake,” said Mr Lineham.

“For the purpose of limiting nutrient discharges to Lake Ellesmere, it is recommended, when considering all water right applications to discharge wastes in the lake catchment, that the discharges be required to take the best practical means to reduce the nutrient loading on the lake from any discharge. .

“For the present application it is considered that the best practical means available on the basis of existing information and reports is the removal of the algal content of the effluent by filtration before discharge. It is recommended that the right applied for be granted subject to this requirement,” Mr Lineham said. The tribunal’s decision will be given at the reserves committee meeting of the board on October 28.