Concrete Slabs Wash Into Channel & Hit Diversion to Hyperion
Concrete slabs wash down the Santa Monica Canyon Channel Sunday morning. Photos: Courtesy of Sharon Kilbride
By Laurel Busby
News & Information Editor
Concrete slabs, which L.A. County Public Works employees stacked on the side of Santa Monica Canyon Channel last week, washed down the channel during the rainstorm Sunday morning and hit a diversion that siphons water to Hyperion Water Reclamation Plant, according to The Canyon Alliance Board Member Sharon Kilbride.
“When the creek was filling up, there was [a] big rumbling down here on the west end, and the concrete is coming down the channel that they left inside the creek, causing blockages down by Short St.,” Kilbride said in an email to county and city officials. “The interceptor near the Short St. bridge, where the water diverts to Hyperion, has been broken again. This is a city project and now is in need of repair…. The concrete is stuck in that interceptor area.”
After receiving her email, Jason Rietze, the Public Works civil engineer who is overseeing the project, sent a crew to the area, but the workers said that the number of slabs that came loose had not caused a problem.
“The vast majority of the stockpiled material was still in the same condition as Friday,” he said in his email. “There were a few small pieces of concrete washed downstream. The city’s low flow diversion is designed to capture low flows not storm flows. So the storm flow was bypassing the low flow diversion as designed and the water was flowing out to the ocean. We will continue to remove the stockpiled on Tuesday.”
Kilbride noted that to her the diversion looked torn apart, and the city took about a month to fix it after the last storm.
The loose concrete slabs are the result of a Public Works project intended to remove a layer of concrete that was installed in the channel in the 1970s. Hundreds of slabs of this layer came loose during a Feb. 16 storm and clogged the channel. That loose concrete was removed, but more concrete overlay remained in other parts of the channel.
Piles of concrete overlay slabs lining the Santa Monica Canyon Channel at Amalfi and East Channel.
Piles of concrete overlay slabs lining the Santa Monica Canyon Channel at Amalfi and East Channel.
To better prepare for anticipated heavy rain this fall and winter due to El Niño, Public Works began a project to remove the remaining overlay on Aug. 27. The staging area is located at Amalfi and East Channel, which held piles of concrete slabs lining one side.
Some of these slabs were washed into the channel by this morning’s rain and hit the heavy plastic diversion that takes creek water to Hyperion, which led to much more water reaching the beach, acccording to Kilbride.
“The pieces of cement just broke it so the water … flooded the whole entire beach,” Kilbride said via text. “It’s changed the whole landscape for the beach. It’s huge on both sides now….. That concrete should’ve been removed before the storm because if the rain got heavier, all that concrete would’ve washed down to Channel Lane where there’s a dip and it would’ve collected, causing the water to make a blockage and then splash over the walls … potentially flooding homes.”
Kilbride requested that all of the concrete stacks in the channel be removed and that the workflow be changed to prevent piles of concrete from being left in the channel in future.
In her email to officials, she asked, “Could you please make sure whoever’s in charge of this project follows protocol, and removes the cement from the channel before any heavy rains to avoid more damage to our infrastructure and potential flooding of the storm control channel in our community? To me, this is common sense.”
After sending a crew to the area to assess the situation, Rietze emailed Kilbride and other officials with his reasoning for not removing the concrete slabs previously. He also promised to remove them more quickly in the future.
“We were not anticipating enough rain to move any material downstream,” he said. “We are actively working to remove the material. All the stockpiled material within the channel will be removed this coming week. We are also renting additional trucks to ensure we can we remove the stockpiled material in an efficient manner going forward.”
For questions regarding this project, contact Public Works Civil Engineer Jason Rietze at (626) 819-1922 or email him at JRietze@dpw.lacounty.gov during weekday work hours. For after-hours assistance, contact LA County Public Works 24-hour Dispatch Center at (800) 675-HELP (4357).
The diversion that normally siphons water to Hyperion was hit by the concrete slabs this morning.
