All development halted in Dayton for foreseeable future due to major engineering mistake
Submitted by Kelsey Penrose on Tue, 11/05/2024 - 12:25pm
Lyon County became aware on Oct. 19 that a major design flaw had occurred at the Aspen Creek Rapid Infiltration Basins project, and as a result, all development is currently being halted within the Dayton Sewer Service Area, according to Taylor Allison, the county's emergency management and government affairs director.
The Rapid Infiltration Basins project, also known as RIB, is a wastewater treatment concept used to treat and dispose of effluent from a wastewater treatment plant. The RIB is a basin that holds the water for a short period as the water is absorbed into the ground.
During warmer months, effluent is used in irrigation, such as at the Dayton Valley Golf Course, but during non-irrigation months, the county depends on RIBs as the primary disposal method of effluent.
In 2022, Lyon County contracted with DOWL, an engineering firm out of Reno, to design and construct the RIB project. The project began in October 2022 and was finished in July 2023. The basins were meant to provide an additional capacity of 1.4 million gallons per day. The initial design and construction of the project cost the county around $7 million, according to Allison.
However, in October 2023, Lyon County personnel noted standing water within the basins, which was not supposed to happen. Over the next three months, the ponding levels continued to worsen, Allison said.
By the end of December 2023, the groundwater was also rising.
In January 2024, Lyon County issued a task order to DOWL to find out what had gone wrong. In March, DOWL finished their investigation and stated they hadn’t found anything wrong with the initial design, and it was inconclusive as to why the RIBS were not functioning as anticipated.
The county then contracted a third party engineering firm to determine the cause of the problems at the RIB. That firm, AtkinsRealis, reviewed the project design and found a number of major design flaws that led to the issues at the RIB. In addition, they determined that the maximum capacity the project could hold would not be 1.4 million gallons, but instead, around 350,000 gallons per day, only about a quarter of the designed capacity.
They said that there are some corrective measures the county could take to increase capacity but that “unfortunately, the capacity of the RIBs are unlikely to ever reach their original design capacity.”
The major design flaw was caused because, according to AtkinsRealis, DOWL used an outdated 1970s study from Arizona to project the capacity calculations. This study also utilized a different soil type than what is found at the RIB site, which further caused issues with the calculations.
In addition, the actual construction of the basins themselves were smaller than the design, which would have allowed for even less capacity even if the soil composition calculations had been correct.
After determining that the basins would only be be able to hold a quarter of the projected effluent, Lyon County immediately halted all development within the Dayton Sewer Service Area for the foreseeable future.
“This issue impacts all developments that are currently in the process prior to the issuance of will-serves, final maps, or building permits,” Allison said. “Lyon County will not be able to issue new building permits in the Dayton sewer service area; however, projects that already have a building permit issued will be able to continue construction. If developers wish to do so, Lyon County will continue to process new applications for Final Maps and Improvement Permits to keep projects moving forward, but will be unable to issue approvals until there is sufficient effluent disposal capacity to support those developments.”
Allison said this issue may impact developments currently in the process before the issuance of will-serves, final maps, or building permits. The county is currently in receipt of two applications for site improvement plans, and there are several projects in various stages of approval. Allison said they are still working to figure out an exact number of potential developments affected.
Allison said there are no risks to domestic wells at this time, nor is there a risk of flooding. The RIBs are located in a remote area of Dayton, and were designed and permitted as a dam, and operated in a manner to prevent spillover, Allison said.
When asked if the county plans to sue DOWL for their major design flaw, and if they will be held accountable to fix their mistake, Allison said the county has retained Matt Addison with McDonald Carano law firm to assist with any related legal matters.
This is a developing situation and we will update with any additional information as it becomes available.
