A skeptical Alameda County judge ordered garbage hauler Waste Management on Tuesday to return to court next week to prove it is abiding by his order to collect all the trash in Oakland or face big fines for scores of missed pickups.

Superior Court Judge Richard Keller, at a hearing in his Fremont courtroom, said Oakland officials provided evidence that as many as 300 customers a day have not been receiving garbage service despite his order last week that the company truck away all the city's trash.

"That's more than ... just a matter of a couple of missed pickups," Keller said to Waste Management lawyers who told him the company is covering all of its routes. "All I'm saying is there's a certain amount of common sense that comes into play here in all this, and then there's gilding the lily."

Keller scheduled a hearing for Aug. 3 to determine whether the company should be held in contempt of his July 19 order -- which could subject the firm to fines of $2,500 per day for each of the hundreds of pickups the city says have been missed since then.

Meanwhile, representatives from Waste Management and the Teamsters union, along with Oakland Mayor Ron Dellums and a federal mediator, spent 10 hours Tuesday trying to work out a deal and planned to resume negotiations at 11 a.m. today in Oakland. A contract agreement would end the company's lockout of nearly 500 union garbage haulers that began July 2.

Dellums said the two sides made progress in their talks Tuesday.

"We have reached agreement on several of the outstanding issues,'' he said Tuesday night, declining to provide details. "I'm actually feeling very good because there was substantial progress. I believe the remaining issues can be resolved -- that's not to say they're not difficult issues."

Since July 19, city officials said they have received 3,000 complaints about spotty trash, recycling and yard waste pickups, while Waste Management officials have said they resumed regular weekly pickups in Oakland and other East Bay areas affected by the lockout.

"Each day it goes on, it becomes more and more frustrating," said Dellums, who described the negotiations as tedious and difficult. Waste Management has hired hundreds of temporary workers to pick up trash in Oakland and other East Bay communities and has added extra drivers and trucks to East Bay routes since Keller's order last week, Waste Management attorney John Lynn Smith said at Tuesday's hearing.

Smith said the company has 117 drivers on routes in Oakland, a number equal to the number of Teamster drivers in the city before the lockout, which came three days after the union's contract with the company expired.

"We'll continue to move forward to make sure people get service," Waste Management spokeswoman Monica Devincenzi said after the hearing, adding that on Saturday temporary drivers will go back over routes to gather any missed pickups from the week. "We truly apologize for any inconvenience we've caused our customers. We're trying our best to get it done."

But Deputy Oakland City Attorney Kandis Westmore said the city has received 200 to 300 complaints about missed pickups each day since the judge's order -- evidence, she said, that the company is not abiding by the order.

The city will have to prove in court that Waste Management has willfully failed to pick up garbage, Keller said. The city's efforts could be undermined, he said, by company claims that Teamster picketers at the firm's office in East Oakland have delayed replacement drivers on their routes by up to three hours.

Keller acknowledged that the potential fines, while substantial, might not motivate the multimillion-dollar corporation. "It's like swatting a gnat off the back of an elephant," he said.

City Attorney John Russo has said the city could hire another hauler to pick up trash in Oakland, but a spokeswoman for City Administrator Deborah Edgerly said Tuesday that city officials will continue efforts to compel Waste Management to comply with the terms of its franchise agreement.

"The performance standards are clearly spelled out -- pick up the trash," Karen Boyd said.

The company's contract with Teamsters Local 70 expired June 30, and Waste Management locked out its drivers in what company officials described as a pre-emptive move against a rumored Teamsters strike.

Union officials said their members did not intend to strike and planned to work while union and company officials negotiated a new contract.

Oakland, Emeryville, Albany, Hayward, Newark and part of San Leandro, along with unincorporated areas of Alameda County, including Castro Valley and San Lorenzo, are affected by the lockout.