PG&E is not backtracking on its promise to clean up the site, McKannay said. Rather, it hopes the extra review will help identify the most appropriate plan.

"PG&E is committed to putting into place a remediation plan that is best for the environment and the community," McKannay said.

She declined to compare the degree of contamination compared to other PG&E sites, but acknowledged the Santa Rosa site is unique.

"The fact that it's right next to a creek and a greenway that people utilize recreationally, these two things are fairly unique in the 40-plus projects we are working on," McKannay said.

She said groundwater monitoring has not shown significant migration of the pollutants, and that materials like coal tar are thick and largely "immobile."

But Ours, the Santa Rosa mayor who was head of San Rafael's Economic Development Department when it dealt with PG&E on a gas plant site in that city decades ago, said he doubts such claims. "If it's there, it's moving," he said.

Construction of the wall strikes him as something the utility should have done first to protect the creek, not last, he said.

"It should be done as soon as possible. The longer it goes on the more it will migrate out," he said.

(You can reach Staff Writer Kevin McCallum at 521-5207 or On Twitter @citybeater.)