FREMONT -- The Planning Commission voted Thursday to allow the Dumbarton Quarry to be converted into a 91-acre regional park, but for some that means the debate is just beginning.

The issue now will go to the City Council for final approval at a meeting scheduled sometime in September, Fremont officials said.

Dumbarton Quarry Associates, a company that operated a crushed rock aggregate quarry at the Ardenwood neighborhood site, has to pay all costs to construct the park,

Construction will include filling the quarry pit, which was 300 feet deep during peak quarry operations. The company is approved to use as much as 6 million cubic yards of soil to fill it.

That part is simple enough -- who would be against converting an ugly quarry pit into a nice extension of nearby Coyote Hills Regional Park?

Well, some are concerned that the 120,000 cubic yards of contaminated soil from the nearby Patterson Ranch development might be dumped in the quarry. That soil has not yet been approved for disposal, but it's just a Regional Water Quality Control Board decision away from receiving the green light. Critics say the contaminated soil might expose visitors and nearby residents to health hazards -- not exactly what nature lovers have in mind when camping on weekends.

It bears repeating that the agenda item approved Thursday only involves the plan to build the 91-acre park next to the Dumbarton Bridge and the Newark border, on the northwestern edge of Fremont.

Between now and September, however, environmental groups, such as Friends of Coyote Hills, likely will be have plenty more to say to the five-member City Council about it.

Contact Chris De Benedetti at 510-353-7011. Follow him at Twitter.com/cdebenedetti.