Government Contracts Case Study: Type II Differing Site Condition

Differing Site Condition (DSC) claims are common in government contracting. In the typical Type I DSC claim the contractor must establish that the condition it encountered differed from what the Contract indicated. For example, rock was encountered not soil.

A Type II Differing Site Condition (DSC) is by definition “of an unusual nature, differing materially from those ordinarily encountered”. In a Type II DSC case, unlike a Type I where the Contract forms a reference point, there is no clear point of reference. Instead, the conditions encountered must be judged by what is normal for the area. A behavioral DSC is even more unique. To establish a behavioral DSC the contractor must establish that that while the ground did not appear to be unusual, the ground behaved in an unusual manner during construction.

Representing a jet grout contractor, Robbie MacPherson successfully led a team which established the existence of a Type II Behavioral DSC involving the construction of two New York City subway stations a block apart. Jet grouting is a method of insitu soil treatment that is commonly used to underpin foundations, provide excavation support, or, as in this case, to create a groundwater cut-off using a watertight base plug for excavation below the water table.

The contractor had extensive jet grout experience, including experience in New York City. It also had available to it the technical experience of its parent company, which performs jet grouting worldwide. Typically, jet grout columns are formed, and their diameter, composition and properties, such as strength, selected to match the design parameters. Column diameter is one of the most important design parameters in jet grouting, as it is fundamental to the construction of a treated zone formed from overlapping columns. Full scale field trials are first conducted to verify the selection of the jet grout parameters, based on successful prior experience. Following its established practices, the contractor devised and implemented a jet grout trial program. However, the trial results were unexpected, unpredictable, and unusual compared to past experience. After several revisions to its testing procedures, which were time consuming and costly, sufficient column diameters were formed at the first station site. The contractor then moved to the second site, a block away, but had to start the trial process all over again when the soil at that site did not react the same when the design parameters established at the first site were employed. 

Establishing the existence of the Type II DSC required proving the experience of the contractor’s staff, the company itself and its parent. Next, we needed to prove that the trial program followed both the industry and the contractor’s normal practice and procedure. Finally, we had to coordinate that evidence with the opinion testimony offered by several expert witnesses. We also worked with the client and experts to rebut the defense put on by the subway authority and its experts. 

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