Officials ensure spill dome integrity

LA CRESCENTA — Los Angeles County officials on Tuesday assured foothill residents that several measures were being taken to ensure the controversial sediment pile would remain stable as the winter rain season kicks into full swing.

The county Department of Public Works and the Flood Control District have been working with a geologist to examine the so-called Dunsmuir sediment placement site by taking dirt samples and using a massive processor that sifts out debris to make sure the dome is properly constructed, Mike Miranda, a public works associate civil engineer, told residents on Tuesday.

Crews also installed a 42-inch concrete pipe to ensure the site drains properly, he added.

County officials are not expecting the Markridge Road site to reach its 2-million-cubic-yard capacity for the next few years, he added, although just 472,000 cubic yards of space remains.

"It is very hard to predict when it will actually get to capacity," Miranda said.

Crews began dumping debris at the site last year as they cleared mud and rocks from 28 foothill-area basins last year to hedge against debris flows into nearby communities.

Before the Station fire, the site had less than 1-million cubic yards of sediment, Miranda said. Last year's winter storms added 450,000 cubic yards of sediment alone, he added.

As crews dumped loads of mud and debris at Dunsmuir, the site quickly grew into a massive dome of dirt, concerning residents who feared the packed site could give way during the next major rainstorm.

Residents have also been troubled by the high volume of dump-truck traffic on residential streets that lead to the site.

Some residents at the meeting voiced concerns about increased noise and air pollution, with one resident pointing out that within five minutes, she counted 31 dump trucks on her street.

Once the site is full, county public works officials said they plan to reinstall a Los Angeles County Fire Department landing pad for helicopters and landscape the area, although those plans depend on the growth of vegetation on the hillsides.

"As soon as the hillsides re-vegetate, the amount of debris will drop drastically," said Steven Sheridan, assistant division engineer for county water resources.

The debris processor — a major source of noise — is scheduled to remain at the site until February and will operate from 7:30 a.m. to 3:30 p.m. Monday through Friday, officials added.