"Hopefully it's some mild rain," said Joseph McRae, battalion chief with the Lone Peak Fire Department. "It seems to be compounding. Each one does more damage because of the saturation levels of our mountains."
Part of the problem over the weekend was clogged basins in the foothills, near the Quail Hollow fire scar, he said.
The city built the basins after the 2012 Quail Fire burned the vegetation that would normally help hold debris back. It takes a lot of work to clear them the lower basin has 25 feet of debris in it. It took four days to clear them last time, McRae said. "They'll probably be working around the clock."
City officials are talking with engineers now about the possibility of digging more basins to mitigate the ongoing threat of flooding. Experts have told the city that it takes a minimum of three years for vegetation on the mountain to grow back to a point where it can sufficiently hold the rainwater, McRae said.
Flooding damage was also reported in Santaquin, Oremand Provo.
About 30 homes in Santaquin reported a foot of water or more in their basements, and 20 reported less than a foot, said city manager Ben Reeves. City officials believe there was more flooding in the north end of Santaquin, but that those cases went unreported as neighbors helped neighbors rather than calling for emergency responders.
"We've never experienced a downpour like this, at least not in our public works director's time with the city, which is 33 years," Reeves said. As in Alpine, volunteers turned out in droves to help, Reeves added.
In Provo, the south lane of Grand Avenue, where it turns into 900 North, collapsed on Saturday under the weight of rain water. Bryant Livingston, a local photographer, shot video of the collapse that shows a waterfall surging off the broken street and into the crumbling hillside.
Floods also washed out the hillside near 1460 N. Jordan Ave., leaving only a flight of concrete stairs hanging in midair. A canal also breached near 2300 N. 1060 West, flooding the basements of several homes, according to the city.
Timpanogos Cave National Monument and State Road 92 were also closed Sunday. While SR-92 opened about 7:15 p.m., the cave was scheduled to remain closed through Tuesday because of slides from rock and debris from the storms.
The National Weather Service in Salt Lake City said Alpine stayed dry on Monday night, but showers were expected to increase beginning Tuesday morning and continue throughout the week.
"The risk for flooding will be elevated," said NWS meteorologist Mike Seaman.