A sewage overflow in Mead Avenue at the weekend was not the first for the Cromwell street, according to Central Otago District Council Water Services Manager, Ian Evans.

A blockage caused by fat in a wastewater pipe in Anderson Park has been identified as the cause of the incident, he said. 

Residents reported seeing and smelling sewage flowing from a maintenance chamber, across the street and into stormwater drains on Saturday. Cars and cyclists, unaware of the issue, were observed driving through the liquid. 

Ian says the height of the Mead Avenue chamber has contributed to past overflows.

“The wastewater maintenance chamber in Mead Avenue is at the lowest point in the catchment. As it is the lowest point, there have been previous overflows but from blockages in different areas of the system.”

The issue of blockages caused by what people send down the pipes is not unique to Cromwell. He urged people to “think before they flush” or before they send fats or oils down the sinkhole.

“There is district wide issue of blockages in the wastewater system caused by non-flushable items such as wet wipes being flushed and fats and oils being rinsed down household drains.

Once fats and oils enter the wastewater system, they solidify and cause blockages such as the one that caused this overflow.”

He said the overflow impacted stormwater which may have resulted in flow to the river area behind Bell Avenue. 

“Samples have been collected and signage has been erected which will remain in place until we have confirmation from sampling that there is no impact.”

He said the clean-up at Mead Avenue had been delayed due to a separate and unrelated issue at Pisa Moorings which involved a pumpstation problem.

An internal inspection of the pipes using CCTV may be undertaken after the council reviews this and past leakage incidents.