A garbage dispute that has left refuse and residents steaming was back in court Tuesday, with lawyers for the city arguing that Waste Management Inc. was defying a court order to take out the trash.

Meanwhile, negotiators for the Houston-based company and the union representing locked-out workers met with a federal mediator and Oakland Mayor Ron Dellums.

Alameda County Superior Court Judge Richard Keller did not make a ruling in the case, but said Oakland officials have presented enough evidence to justify a contempt hearing Aug. 3.

Problems began in early July when Waste Management locked out nearly 500 employees after contract negotiations broke down with their union, Teamsters Local 70. The company hired replacement drivers and says it is close to being back on schedule, but city officials and residents say piles of garbage have been left to rot.

Oakland officials won a court order from Keller earlier this week forcing the company to resume full services. City officials were in Keller's Fremont courtroom Tuesday to tell Keller that the company is not complying with that order.

Oakland Deputy City Attorney Kandis Whitmore said the city is getting hundreds of calls per day about missed pickups.

Oakland officials want fines of $2,500 imposed for missed pickups.

Keller told attorneys the city would have to prove that Waste Management deliberately failed to make pickups. He noted the company has claimed that picketers have delayed drivers.

Waste Management attorney John Lynn Smith said the company is following the court order and has at least as many drivers covering Oakland now as it did pre-lockout. He acknowledged there is a backlog of uncollected trash, and some drivers are missing pickups because they are unfamiliar with the routes, but said the company is working to correct those issues.

Outside the courtroom, Waste Management spokeswoman Monica Devincenzi apologized to customers who haven't had their trash picked up.

"We truly apologize for the inconvenience that this has caused them. We are trying to get it done and as reports come to us of misses, we do make sure that we roll a truck out to get those picked up," she said.