Sidewalks. Roads. Culvert pipes. Before any project involving soil becomes tangible, there’s an important step most people never see.

Engineers first run tests to ensure the ground is dense enough to provide a stable foundation. Loose soil settles and can lead to potholes, cracks, and other deformations in the structure. Engineers compare the potential density of the soil in ideal conditions with the actual density of the soil on location. If the field soil reaches a specific percentage of the ideal density, it passes.

To enhance their understanding of geotechnical testing, St. Lucie County Engineering staff recently visited the testing lab of the Ardaman & Associates, Inc. branch in Port St. Lucie.

County Engineer Dan Zrallack, PE, organized the tour.

“If you see how the Proctor Test is run, you’ll gain a better understanding of the physics of it,” said Zrallack. “That heightened awareness will ultimately improve how County staff evaluate projects in the field.”

Performing a “Proctor Test” in the lab involves placing a soil sample into a mold and compacting it in layers. This is tested at different moisture levels. The process ultimately identifies the ideal moisture content at which soil becomes densest when it is compacted.

Inspectors in the field verify that construction activities conform to the project plans, specifications, and County standards. This includes assessing subgrade and roadway base material for density, bearing, capacity, and quality. Information collected at the project site is compared to the Proctor Test results to determine if the material passes inspection.

“Every job that I do, we have densities,” said Jason Kenna, Construction Inspector III. “Especially under sidewalks, roads, they really come into play there.”

Kenna says activities like this tour can help everyone gain a better understanding of the work and how it ties into the entire project.

“To see the process and how long it takes to get results is really helpful when coordinating the schedule for a job,” said Kenna.

Ardaman & Associates Branch Manager Chris Tornello, PE, led County staff on the tour. He and members of his team discussed this test, as well as other geotechnical testing capabilities.

“Tours like today are beneficial in helping everyone understand what these test results mean, how to get them, and the value behind them,” said Tornello.

The County has contracted with Ardaman and several other local geotechnical engineering companies to provide geotechnical expertise on culvert repairs, stormwater improvements, and roadway resurfacing projects, among others.

The Engineering Division is responsible for the Capital Improvement Program as approved by the Board of County Commissioners. Staff manage the surveying, design, permitting, construction, and fiscal control of individual projects.