Nicholson in the Neighborhood: Virginia's North Hill Project-Video

Video Transcription

Video Summary

The presentation covered two anchored beam-and-lagging retaining walls built for separate residential developments in Alexandria, Virginia. The 33-acre site had a history of slope instability and highly variable coastal plain soils, including perched water, clay layers, slickensides, and running sands. These conditions complicated working-platform preparation, pile drilling, and hole stability, while county review requirements and limited access added design constraints.<br /><br />The design used large-diameter drilled piles and multiple rows of high-capacity anchors, with shotcrete and a boulder-style architectural finish. Construction required temporary casing, changes in drilling methods, careful anchor installation and testing, and ongoing management of water and ground conditions. A backfill and compaction problem caused localized wall movement during anchor stressing, highlighting the importance of coordinating earthwork. Drain boards, weep holes, and drainage outlets managed water in the completed walls. Six months of monitoring showed movement generally remained within the two-inch limit.

Keywords

anchored retaining walls

beam and lagging

Alexandria Virginia

slope instability

groundwater drainage