DT 325 SPT OTE Simplifies Shift to Geotechnical Sampling

Environmental/construction consulting and testing firm based on Long Island, New York, JC Broderick & Associates Inc initially focused their subsurface division on environmental sampling including, Phase II projects — installing monitoring wells and sampling soil and groundwater for contamination. As their work with school districts in Nassau and Suffolk counties expanded, their balance of environmental to geotechnical sampling work began to transform during 2014-15.

“There was a time when we were barely doing any geotechnical work and now it’s flipped,” Jeff Nannini, project manager, said. “We’re now 75% geotechnical and 25% environmental.”

When a school district's architect designs a building addition or athletic field renovation, they call on the subsurface division to conduct geotechnical sampling. They opt for the DT325 SPT OTE method of SPT testing for several reasons:

• worker safety
• consistency
• speed of drilling
• lack of soil disposal

Not only did the DT325 SPT OTE system streamline their switch to geotechnical, but it also made geotechnical sampling simpler for their clients.

“With OTE, there’s no soil cuttings, which is great at a contaminated site,” Nannini said. “Our clients don’t have to deal with the extra cost of drumming and disposing of soils.”

The DT325 SPT OTE system facilitated a seamless shift from environmental to geotechnical investigations.

“Using the SPT system on our 7822DT has definitely improved our productivity since transitioning from casing to sampling only takes moving one lever,” Nannini said. “We already had the 3.25 rods for environmental sampling and 1.5-inch rods for groundwater sampling, so we only had to invest in the automatic drop hammer and split spoon samplers. There was very little additional cost.”

Overall, they appreciate the DT325 SPT OTE system efficiency and reduced SPT testing site repercussions.

“At a hotel construction site, engineers were concerned about the soil conditions behind a preexisting retaining wall. The construction manager built us a ramp to get behind the retaining wall to advance two borings using continuous SPT,” Nannini said. “The borings were not unique, but the job could not have been performed without a Geoprobe^®. The results of the borings satisfied the engineers that no additional soil improvements were needed.”