The Gridley Sports Complex, located in the city’s Industrial Park, is a multi-phase recreational development. Designed by Freepik, www.freepik.com

GRIDLEY, CA (MPG) - Alarmed by unstable soil conditions at Gridley’s new sports complex, city officials fear the discovery of “quicksand” beneath proposed lighting foundations could inflate construction costs and challenge what the city has budgeted for the project.

During the Oct. 7 City Council meeting, contracted City Engineer Dave Harden, co-owner of Bennett Engineering, whose firm has provided engineering services to Gridley since 2016, reported that a 16-foot test hole drilled for a lighting pole sank 11 inches within an hour, and further drilling revealed roughly 22 more feet of clean sand, which were conditions the design team had not anticipated during initial planning.

To address the unexpected conditions, Harden recommended a $38,661 increase in the city’s contract to cover deep soil borings so Crawford & Associates, a geotechnical firm subcontracted through Bennett, could provide the necessary soil data to finalize structural designs for the lighting foundations, which must meet wind and seismic safety standards.

The Gridley Sports Complex, located in the city’s Industrial Park, is a multi-phase recreational development funded in part by a $3 million Proposition 68 Rural Recreation and Tourism Grant, with the city responsible for all remaining costs, which are already approaching $1 million. Plans call for three multi-use sports fields designed to accommodate youth soccer, football, and baseball leagues, addressing a long-standing shortage of practice and play space for local teams and city-sponsored programs.

The first phase of the $4 million budgeted project, which has already begun, includes a lighting system featuring seven galvanized steel poles, each 70 feet tall, designed to support LED luminaires with glare and spill control. The system is engineered to meet IES Class III standards, providing recreational-level illumination suitable for youth sports, according to the bid documents.

The proposed contract amendment failed to gain traction with only four members of the Gridley City Council present for the discussion.

Vice Mayor Bruce Johnson voted no on an initial motion to approve, citing concern over open-ended costs. Councilmember Catalina Sanchez abstained, saying she lacked sufficient information after pressing Harden on whether more thorough soil testing should have been conducted before construction began.

Harden explained that the city had relied on a conservative bid estimate using assumed soil characteristics and FEMA data, which showed no major subsurface hazards. He said the design for the light poles was based on the best soil data available at the time to avoid delays and keep the project moving forward.

“But this is like quicksand,” Harden said. “It’s just a different animal that contractors aren’t used to dealing with.”

While “quicksand” was used informally throughout the discussion, the U.S. Geological Survey provides a more technical explanation for the geologic hazard known as “liquification,” which occurs when loose, water-saturated soils lose strength, causing the ground to behave like a liquid.

According to the U.S.G.S Earthquake Hazards Program, “liquefaction is a phenomenon that is caused by earthquake shaking. Wet sand can become liquid-like when strongly shaken, leading to ground failure and structural damage.”

According to the Butte County General Plan 2040, areas of Butte County most susceptible to liquefaction include the southwestern portion of the county, particularly near the cities of Biggs and Gridley, where groundwater levels are high and soils consist of unconsolidated alluvium. Liquefaction can result in significant ground failure, including lateral spreading, loss of bearing strength and ground settlement, the general plan states.

While the City of Gridley’s General Plan 2030 states that seismic risk is not a major issue for Gridley, compared to other parts of California, the plan does note that earthquake-induced conditions such as ground shaking, liquefaction and ground failure are still relevant and must be considered in local hazard mitigation efforts.

Mayor Mike Farr, drawing on his knowledge of past infrastructure projects, said soil conditions at the sports complex site are like those encountered during other construction in the area.

“That quicksand is known from old sewer mine construction,” Farr said. “Its depth fluctuates.”

With no clear path forward, the council tabled the action to the next meeting for staff to gather more information, cost comparisons and options.

Harden’s recommendation is to drill three 38-foot borings to provide an average soil profile and proceed from there. The council also may consider boring at the location of all seven light poles, which would offer site-specific data but require more time and funding. 

“We need transparency and assurance that we won’t face unexpected expenses,” Sanchez said. “There can’t be another surprise.”

Harden said he could offer no assurances until they determine how deep the contactor must go to reach stable ground.

“We want to know where that firm foundation is so that we can build a foundation for these lights,” Harden said.

The City Council is expected to decide how to move forward at its Oct. 21 meeting to curb further delays on the project. Due to the grant specification and funds expended so far, a change in location to another area of the city is not an option, officials said.

Sources: U.S Geological Survey, Butte County General Plan 2040, Gridley City Plan 2030.