Ray Sandiford presented the March Geotechnical Lecture at the CUNY Graduate Center in Manhattan on March 15, 2007 to a standing-room only audience of over 200 attendees. The lecture focused on geotechnical aspects of the redevelopment of the World Trade Center (WTC) site, both those currently underway and those still in planning.

Mr. Sandiford began the lecture by describing the Port Authority's facilities in the region, and detailing the history of the WTC site. The site occupies much of the west side of lower Manhattan. About half of the site was once in the Hudson River and was underlain by either fill or deposits of organic silts. The original PATH system tunnels crossed the site and terminated in the old H&M Building. In addition, the 1 and 9 subway lines crossed through the site. The original excavation for the WTC construction provided the fill used to create the Battery Park City development.

The Geotechnical Group began the New Year with a lecture on January 11, 2007 that included a pair of presentations by Dr. Allen Sehn and Dr. David Yang, distinguished engineers with experience applying deep soil mixing methods to a variety of geotechnical design challenges. Dr. Sehn kicked off the lecture with a general overview of soil mixing methods, particularly emphasizing the use of single axis mixing. Deep soil mixing involves mechanically incorporating a cementitious binder into soft in-situ soils for the purpose of improving the strength and stability of the soil. The result creates soil-crete columns which are typically three feet in diameter, but which can be as large as seven feet across. These columns are constructed one after another to create configurations within the ground such as walls or grid patterns. The primary factors which most affect the overall performance of mixed soils are the initial soil conditions, the mixing energy applied to the soil by the cutting tool and the content of binder material added during mixing.