Dilemma over sewer tanks

22:03, Jun 06 2014

Underground sewer tanks could be placed on grass berms outside people's properties if they object to having them on their own land.

Christchurch City councillors have this week been discussing the rollout of a controversial pressure wastewater system in parts of the city.

The system involves an individual tank and pump. The pump is located in an underground tank and transfers wastewater, under pressure, from a house to the council's pipes in the street. The tank is located near the house.

However, there is no process for dealing with homeowners who are adamant the tank is not installed on their land or that it can be installed but power cannot be supplied from the house.

Council network planning team leader Simon Collins suggested homeowners unwilling to have the tank on their property could have it placed away - provided the additional costs were borne by the homeowner.

Cr Pauline Cotter questioned whether people who had already agreed to have underground tanks on their properties would seek to get them moved to the publicly-owned berm and the visual impact that could have on the city.


Collins agreed that was a possibility.

Some 1300 tanks had already been installed on private properties and he expected there would be some backlash.

However, the off-property option may not be suitable for all properties as it is dependent on how the system is interconnected.

A separate report on how to deal with homeowners who refuse to install the system or allow a power connection is being prepared and is expected to go to council in the near future.

Councillors voted to install pressure wastewater systems in about 35 properties across the Menlo Terrace, Broad St, Lansdowne Terrace and Cashmere-Macmillan Avenue catchments.

However, the gravity system will be repaired for properties in the North New Brighton catchment as it is believed more cost effective.

A decision on whether to offer owners who did not want the system on their property the option of paying the additional costs for having it off-site was deferred to another day.

Likewise, councillors also deferred the decision to install the pressure system in 107 properties in the St Lukes catchment.

Collins said the pressure sewer was the best technical solution because it provided resilience.

"In the event of a future earthquake large enough to cause liquefaction, a pressure sewer system provides the highest likelihood of a sewer system continuing to function, and, if it is not functioning, will be the quickest and easiest type of system to repair."

The Press