Nicholson in the Neighborhood: Virginia's North Hill Project-Technical Paper Upload

Technical Paper Upload

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The North Hill development in Fairfax County, Virginia, required two permanent anchored soldier-pile retaining walls to support a new residential community and public park on a site with a history of slope instability. Built through a design-build partnership between Nicholson Construction and GEI Consultants, the walls extend 800 and 1,000 feet, reaching a maximum height of 40 feet.<br /><br />The site’s highly variable, overconsolidated Potomac Group soils included plastic clays and silts, sands, and potential slickensides. Design analyses considered short-term construction, serviceability, and long-term global stability. Residual soil strengths governed the design, leading to deep 30- and 36-inch soldier piles and long, high-capacity strand anchors, with bond zones extending beyond potential failure surfaces. The walls incorporated temporary timber lagging and a permanent architectural shotcrete finish.<br /><br />Construction encountered perched groundwater, running sand, collapsing drill holes, and abandoned drainage infrastructure. Crews adapted by adding temporary top casing and, where needed, using segmental casing to maintain hole stability. Pandemic-related shutdowns and material delays added logistical challenges.<br /><br />A total of 158 anchors were installed and tested. Survey monitoring showed average wall-top movement of less than 0.5 inch—well below the 2-inch design limit—and no long-term creep was observed during five months of post-construction monitoring. The project illustrates how flexible drilling methods and careful geotechnical design can address difficult ground conditions while achieving both structural and aesthetic goals.

Keywords

North Hill

Fairfax County

retaining walls

soldier-pile walls

design-build

geotechnical engineering

Potomac Group soils

groundwater challenges

strand anchors

slope instability