The Feb. 17 findings follow Harden’s October report, when a 16-foot test hole sank 11 inches within an hour and deeper drilling revealed more than 20 feet of clean sand. Photo by Seti Long

GRIDLEY, CA (MPG) - Gridley’s long-planned sports complex is facing another setback after new geotechnical findings revealed widespread soil instability beneath the proposed lighting foundations. The quicksand-like conditions have prompted the City Council to authorize a specialized seismic study to determine whether the project at the industrial park can move forward as designed.

Contracted City Engineer Dave Harden, co-owner of Bennett Engineering, told the council on Feb. 17 that six of seven deep borings showed signs of liquefaction, a condition in which loose, water saturated soils can lose strength during an earthquake.

“All but one show signs of liquefaction at varying depths,” Harden said, noting that the soil at the selected site does not fall into any standard category used for structural design.

Because the soil profile is outside normal engineering classifications, the structural engineer is requiring a $20,900 resonant frequency analysis to determine how the 70-foot light poles would behave during seismic shaking. Harden said the consultant will evaluate how the concrete foundation interacts with the surrounding soil and whether the current 42 inch wide, 30 37-foot-deep shaft design must be widened, deepened or reconfigured to meet building code requirements. Only one boring, identified as Pole No. 5, showed suitable material for construction, Harden said.

The Feb. 17 findings follow Harden’s October report, when a 16-foot test hole sank 11 inches within an hour and deeper drilling revealed more than 20 feet of clean sand. Harden described the material as “like quicksand” and warned that additional testing would be needed to finalize the foundation design.

The sports complex is funded in part by a $3 million Proposition 68 Rural Recreation and Tourism Grant, with the city responsible for remaining costs that have already climbed to roughly $760,000. Council members questioned whether the new study could lead to further expenses or force changes to the lighting plan. Mayor Mike Farr said he does not want the city to spend heavily on studies only to discover that lighting cannot be installed at all.

Harden told the council he has already notified the state grant administrator of the complications. Removing lighting from the grant scope is an option, he said, but it would leave the complex without nighttime use. Harden said the upcoming study is expected to show how the foundation design must be modified, not whether the project is doomed. He said the analysis will determine whether the shafts need to be wider, deeper or otherwise adjusted to meet seismic standards, describing the issue as a design problem rather than a fatal flaw in the site conditions.

The project must be completed by June 30, 2028, under grant requirements. Farr urged staff to secure written confirmation that the deadline could be extended if needed, citing the soil complications and potential delays.

Construction on irrigation and other site work has already begun, but crews are waiting for the lighting foundation design before installing turf or landscaping, officials said.

The council voted unanimously to approve the additional $20,900 study, hoping it will provide the clarity needed to move forward.