EXTERNAL FLUSH METHODS WITH GROUT FOR MICROPILE INSTALLATION-Video

Video Transcription

Video Summary

Mokhtar Katari described a New York City project converting a historic two-story building into a residence with a 30-foot excavation and two basement levels, including swimming pools. The site’s challenging conditions—fill over running sand, a high water table, restricted access, and adjacent buildings—made conventional micropile installation difficult. The team adopted an external-flush method, circulating fluid grout through the casing and out through an under-reamer to stabilize the sand while advancing piles. The grout also helped seal gaps between the tangent piles, limiting water seepage and soil loss. The installation included roughly 324 tangent piles and permanent micropiles and mini-caissons, with load tests conducted to meet New York City code requirements. Although some localized leakage required additional grouting, the method proved effective and offered schedule and cost advantages over alternatives. Katari emphasized that the approach was permitted as an exception because of the site-specific conditions and the contractor’s relevant experience.

Keywords

New York City construction

micropile installation

external-flush method

tangent piles

deep excavation

groundwater control