Wingham Sewage Treatment Plant

Wingham Sewage Treatment Plant treats on average 1.2 million litres of sewage daily. It is an extended aeration plant utilising biological processes followed by ultraviolet disinfection. Approximately 50% of the treated effluent is beneficially re-used for farm irrigation at Wingham Bight with remaining effluent discharged to the Manning River.

A requirement of the Wingham sewage treatment plant Environment Protection Licence (# 1581) is to meet concentration limits for specific water quality parameters from treated effluent discharged into the Manning River. The Wingham licence has a range of concentration limits listed including 90 percentile and 100 percentile limits. These limits relate to the monitoring of results throughout the licence period.

To meet a 90 percentile limit, the monitoring results must not exceed the specified concentration limit for 90% of the time during the monitoring period. The 100 percentile limits are not to be exceeded, alternatively the maximum concentration.

The Wingham licence monitoring period is reported upon annually with an anniversary date of the 1stof March. As a condition of the licence the treated effluent is monitored monthly, discharge concentration limits are specified for the Biological Oxygen Demand (BOD), Total Suspended Solids (TSS), Ammonia and ph. The corresponding concentration limits specified in the licence for each of these parameters are listed in Table 1. The licence also stipulates fortnightly monitoring of the treated effluent for faecal coliforms. There is no specific concentration limit requirement for faecal coliforms.