Our professionals have been practicing in the local area since 1974. We know the local area, what to look for and how to design the site characterization.

Geologic Setting

A good understanding of the site geology is necessary to determine if test borings, in-situ testing, remote sensing or other tools will likely be more efficient. In areas of uniform geologic conditions, less test borings are needed than in areas that are likely to exhibit significant changes in short distances. Sampling and testing methods are different. For example, Shelby Tubes and consolidation tests are not likely to be needed in hard shallow rock areas, but may be necessary in soft soils. In-situ Dilatometer testing is appropriate in loose to medium dense soil, but Pressuremeter testing is better for hard soils.

The geology of the Mid-Atlantic Region is very diverse. Washington D.C. is located on the fall line where major changes in geology occur. To the West of the fall line, sedimentary and metamorphic rock is shallow and the cost of excavating hard rock can be problematic. To the Northwest, limestone pinnacles, sinkholes and caverns are overlain by very soft soils in the Frederick Valley. To the East, rock is over 1000 feet deep and the coastal plain soils are highly variable. These deposits may include very loose wind deposited sand, very soft marine clays, inter-bedded layers of soft to stiff clay and loose to dense sand. The Miocene deposits are known to be a problem and they extend very deep. Higher elevations are sometimes capped with very high quality deposits of dense sand and gravel. There is a wide band of highly plastic clay along the fall line, roughly paralleling Interstate 95. These alluvial soils were deposited by rivers that no longer exist in large details. Many structures have been damaged by landslides and by shrink-swell in these soils problematic soils.

Generalized Geologic Map of Maryland



Generalized Geologic Map of Mid-Atlantic States