Halifax's failed sewage treatment plant is set to partially come back online within the next few days.

James Campbell, of the Halifax Regional Water Commission, said the plan is to bring raw sewage back into the $54-million plant where solids will be screened out, but the effluent will not be treated.

The sewage will then be discharged into the middle of Halifax Harbour where the problem will not be seen or smelled.

"We expect it to solve the problems of floatables and odour," he said Monday.

Crews will begin testing first with fresh water within days, he said, followed by sewage and wastewater.

As part of the preparations, the eight combined sewer outflows on the waterfront are being pumped out this week to clean them of months of accumulated sludge.

"They have become small septic tanks that have filled up with residue," Campbell said. "We are getting rid of it."

Residents are being warned that pumping may be noisy and smelly. The station at the corner of Barrington and Inglis streets in the south end will be pumped out later this week.

Campbell said the plant's electrical systems have undergone a major overhaul, with key electrical components being moved to street level where they cannot short out in a flood. Generators are also being reconfigured so they do not overload.

The city has agreed not to go after the builder to recoup costs until after the plant is back in operation.

Hydrogen sulphide caused smell

Halifax Regional councillors will get a full briefing at their meeting Tuesday.

The plant malfunctioned in January following a series of power failures on the peninsula. Since then, more than 80 million litres of raw sewage has been flowing into the harbour every day.

There have been major problems all summer with a stench coming from a catch basin located under Cogswell Street near the Halifax waterfront.

Air quality tests for downtown Halifax showed levels of hydrogen sulphide gas, which smells like rotten eggs, spiked on 31 days this summer, causing the stink.

On 13 days, levels of the gas were about 10 parts per million while on eight days, readings exceeded 50 parts per million. On 10 days, the readings were 100 parts per million or above.

All efforts by the city to reduce the stink — such as installing carbon filters, deodorant blocks and ozone machines — failed.