HONOLULU -- Officials are trying to determine who's at fault after tons of concrete was poured down a Windward Oahu sewer pipe and forced raw sewage into several Kailua homes.

Liz Asteriadis suspects a black substance climbing up the walls in her home is the result of sewage that backed into her Windward Cover condominium on Oct 13.

"You could smell what it was right away. It was nasty and my friend Barbara, I called her screaming at 11 o'clock at night. 'Ahh! We are having a sewer flood,'" Asteriadis said.

The putrid water also filled the Windward Cove condominium's lower parking lot.

"It just smelled really bad and they had signs saying 'Warning this is toxic and dangerous,' but they never really did tell us what was going on," Windward Cove resident Erin Dowsett said.

The sewage backed up after a city contractor filled several manholes with concrete, thinking they were filling abandoned lines. When they realized they'd plugged Windward Cove's sewage outlet, they built an emergency pipe. Then they started the difficult process of digging hardened concrete out of the underground system.

Workers are using jackhammers to chip away at the concrete.

The city said its contractors got bad information from the manager of Windward Cove. Windward Cove's management wouldn't talk to KITV. Residents were told it was the city's fault.

"We talked to the association today and they are not going to handle it. It's up to the city or the contractor who filled up the manhole with cement," Asteriadis said.