Many questions remain unanswered about basement construction in Palo Alto, the Planning and Transportation Commission agreed Wednesday night.
Without a vote, the commission postponed potentially recommending restrictions until a later meeting.
Some commissioners and residents remain concerned about the massive amounts of water — as much as 12 million gallons — pumped out for the construction of some basements. Basements also require about 300 tons of concrete, a significant source of greenhouse-gas emissions.
"I can tell you that a lot of people in town are indignant," resident Ellen Wyman said. Her neighbors have had trees die, foundations shift and old basements begin flooding after the construction of new basements, she said.
"When that many people perceive it as a problem, it's a problem," Wyman said.
Yet if the city makes it harder to build basements, homeowners will be more inclined to build out or up, Norman Beamer said.
"It will significantly decrease the value of the property," he said.
About three to seven residential basements are constructed per year in Palo Alto that require water pumping, Senior Public Works Project Manager Bob Morris said.
The city now restricts "dewatering" to April through October to prevent overstressing the storm-drain system, Morris said.
But the city hasn't found any pervasive problems for trees, foundations or the groundwater, Interim Planning and Transportation Director Curtis Williams said.
"It's not a pervasive type of concern we hear from neighbors," Williams said.
And even if dewatering did affect a nearby residence the city couldn't do anything, Chief Building Official Larry Perlin said.
"It becomes really that one property owner is being harmed by the actions of another property owner. The two property owners have to resolve that amongst themselves," Perlin said.
The commission could require basements to be set back from property lines, limit the amount of water removed or the time pumping can continue, or it could require basement builders to add additional environmental features to their house to offset the effects of the concrete, a city report states.