As more flow arrives at the Christchurch Wastewater Treatment Plant due to repairs to damaged pump stations in the network, the potential exists for high levels of odour to permeate parts of the city.
With many broken pipes in the city, flows are high due to groundwater getting into the broken pipes and there is a high sand and silt load in the flow which causes problems in the sedimentation stage.
City Water and Waste Manager, Mark Christison, says, “There has been significant damage to tanks and equipment at the Christchurch Wastewater Treatment Plant as a result of the recent earthquake.
“Hundreds of tankers each day are discharging a mixture of sand and sewage from the broken reticulation into a large tank at the treatment plant to enable the separation of sand and silt material so that further damage to the treatment plant is avoided. This operation unfortunately also causes increased odour potential.
“No secondary treatment is able to be provided at this time due to damage to the final clarifiers; however a temporary treatment phase has been put in place, with the aim of keeping the load on the oxidation ponds low.
“We apologise to residents for the increased odour caused by the current situation. Every effort is being made to repair the critical equipment so that full secondary treatment can be brought back on line.
“Assistance being provided from other treatment plants around the country is much appreciated. It will however be several weeks before damage assessments can be completed as ground water levels need to be lowered so that tanks can be emptied and inspected”, says Mr Christison.