Employees of O'Reilly Auto Parts clean up on Friday, Oct. 3 after a Sept. 29 flood. Up to three inches of mud and water flowed into the store. [Photo by Eric Trenbeath / Moab Sun News]

A torrent of water, mud and debris poured into the south end of town on Monday, Sept. 29, flooding residents, businesses and a portion of U.S. 191 following a burst of intense rainfall.

The flow came down off the rocky slopes beneath the Moab Rim, much of it channeling down Jackson and Boulder streets, before turning north onto U.S. 191 and eventually flooding Village Market plaza.

“Holy moly,” said Krystal Bulman, a checker at the Village Market. “All of a sudden you could see all this mud coming down the hill. It went all the way back to aisle four.”

At the corner of Jackson Street and U.S. 191, O’ Reilly Auto Parts took on three inches of mud and water through the entire store, according to employee Dave Hester.

“But we stayed open and served the public,” Hester said. “Can’t say much for our shoes and socks though.”

In the May Estates subdivision, residents did what they could to stem the flow of the flood as it filled yards and driveways, while county road crews provided sand bags. Above Jackson Street, rocks and water poured down from the cliffs, carving a trench next to the road up to six feet wide and three feet deep.

Jeanine Montague, a resident of Jackson Street since 1998, said that she had seen floods there before, but nothing like that.

“We were just sitting there and thought the wind had picked up,” she said. “But it was the sound of rocks and boulders coming off the cliff. It was intense.”

Steve and Beverly Bunge, who live near the top of Boulder Avenue, said they had seen floods a few times since moving there in 1996. But the conditions worsened when the county built a new diversion system at the top of the street to expand the subdivision, they said.

“The water used to run over there,” Steve Bunge said. “But then they wanted to develop lots so they diverted it over here and down the street.”

Beverly Bunge said that the flow of water was “just like a river,” and that it came to within an inch of their front door.

“They need to be doing something about this,” she said.

Kathy McGill, a Moab resident who has been involved with drainage issues in the area since 1999, also said that the county didn’t provide adequate storm drainage when the new subdivision was built. She said the county knew there were runoff issues in the area, and that part of planning should be to make sure that new developments don’t worsen an existing problem.

“How many more times do the neighborhoods and businesses have to be flooded out before this becomes a priority?” she asked.

The Spanish Valley Storm Drain Master Plan identifies Boulder Avenue and Jackson Street as high-priority project areas. On a scale of 0-4, both are rated as 4 for their potential to cause damage, as well as for commercial and residential inundation.

Horrocks Engineers of Pleasant Grove, Utah, updated the plan in 2011 to help the county prioritize and make cost estimates for the recommended drainage improvements in Spanish Valley. The plan designated new standards for the detention and conveyance of storm drainage based on peak flows from a 100-year flood.

“Essentially, everything that Grand County has built in the past is deficient, according to the new criteria,” Grand County Road Supervisor Bill Jackson said.

Jackson said it would cost around $30 million to implement every aspect of the storm drain master plan.

In 2004, the county leased land from Mark Horowitz to build a retention pond about 400 yards above the top of Boulder Street. The pond is constructed with an earthen dam that traps water and then feeds it into an asphalt lined drainage ditch via two outlet tubes. The drainage ditch conveys the water directly into the street.

The flood on Sept. 29 completely filled the pond with mud and rocks, and the water flowed over the top of the dam. According to Horowitz, that is what the pond is designed to do.

“This pond did its job,” Horowitz said. “It kept all of the mud and rocks from flowing out into the street.”

Jackson said that the detention pond was constructed to hold 1.6 acre-feet of water and flood debris, but that the updated storm drain master plan specifies a pond design of 4.6 acre-feet. (One acre-foot equals about 325,851 gallons of water.)

Further plans for storm drainage improvements on Boulder Avenue include a buried 72-inch conveyance pipe that would pass underneath U.S. 191, and continue under the property owned by Rick Thompson of Rick’s Glass. It would eventually enter the city before emptying into Pack Creek.

Thompson said that the county has his full support in running the pipe through his property.

“To me, it’s a no-brainer,” he said. “We’ll give you whatever you want. It’s good for me, it’s good for the people downstream.”

Thompson, a lifelong resident of Moab, said that a flood of this magnitude happens every 10 to 20 years. But it affects different people in different places, he said.

“This is the worst that’s happened to us,” he added. “But no matter what you do, someone is going to get it.”

Cost estimates for storm drain improvements down Boulder Avenue are close to $900,000 and include the buried 72-inch conveyance pipe and enlargement of the detention pond. A 48-inch pipe that was buried previously beneath U.S. 191 would have to be removed and replaced with a 72-inch pipe to comply with the new standards.

On Jackson Street, the storm drain master plan calls for the construction of a 2.5-acre detention pond, channel improvements and a 66-inch conveyance pipe to deliver water into a storm drain on 400 East. Cost estimates also total approximately $900,000, and Jackson said that project is currently on the county’s list for Utah Permanent Community Impact Fund Board (CIB) funds.

“These projects are on our radar,” Jackson said. “But it’s a funding issue, as well as bringing it up to standard.”

“We understand there’s an issue on Boulder and Jackson, but there are other areas in the county that receive flooding as well,” he said. “We are working on it to the best of our ability, funding and equipment.”

Neighbors say they would welcome improved drainage 

This is the worst (flooding) that’s happened to us.