This Project involved the construction of a new wastewater pre-treatment facility for an abattoir and included the construction of a 5000m3 anaerobic lagoon and a 4000m3 Sequencing Batch Reactor (SBR) lagoon. The anaerobic lagoon was lined with 1.5mm thick PE liner and a PE cover fitted with a gas collection and release system. The SBR lagoon was lined with a PE liner and no cover. Both ponds were fitted with drainage to relieve ground water pressures and fitted with a leak detection system.
Six main pipelines were installed. The main delivery 180PE pipe line transferred effluent form meat processing plant across the Waitakaruru Stream via a rail bridge to the new treatment facilities. Other pipelines included a 180 dia. interconnecting pipeline, carbon feed pipeline, discharge pipeline, waste recirculation pipeline and stormwater pipelines, totalling a length of 930m.
An interstage building between the two lagoons was built housing control valves, flowmeters, and the main MCC and Gas flare control panel. The block building was cut into the lagoon embankment and a block retaining wall and concrete slab area housed the gas flare and transformer (both Principal supplied).
Installation of Principal supplied aerators and mixers in the SBR pond and the electrical instrumentation, controls and SCADA system were also part of the project scope.
A revised method of construction for the ponds was developed with the Engineer. This involved importing granular material and capping the embankments to receive the PE liner. Suitable on site material was found and used where appropriate to reduce the cost of imported material.