World Trade Center Subsurface Profile 2

I have been asked to be on a panel that discusses the engineering ramifications of the WTC disaster. I've practiced geotechnics for twenty years, but not in NY City. While I'm somewhat familiar with the general geology, does anyone know the general subsurface profile in the area of the World Trade Center? I understand that much of this area was built up using hydraulic fill during the first fifty years of the previous century. What is the typical depth of fill? The typical depth to rock?

Any help will be valuable and I will give the contributor credit.

Thanks.

 

[ishvaaag]

El atlas de la construcción metálica, by Hart, henn, Sontag lists

Foundation at -22.5 m at actual bearing pressure 39 kgf/cm2 on rock. Foundation wall 90 cm thick, tied aback. Columns on 2 layers of beams, then footing. Bottom slab 2.10 m thick.

Some graphical details are given in the text.

 

[CISGeotechnical]

Also you may find particular information on general bedrock characteristics of the WTC at the classical 1974 textbook from R.B. Peck, W.E. Hanson and T.H. Thornburn, Foundation Engineering, 2nd ed., John Wiley & Sons, for some of us considered a Bible in Foundation Engineering.

For example, p. 360 have an illustration of what they looked like and read like this:
World Trade Center
"The twin steel towers, rising to a record height of 1,350 ft or 110 stories rest on the Manhattan Schist at a depth of 70 ft below street level. Estimates of the deflection of the towers under wind forces required evaluation of the modulus of elasticity of the supporting bedrock by means of large scale in-situ testing. Excavation of the entire 16-acre site occupied by the Center involved removal of 16 million cu yd of fill, soil, and rock; continual support of two operating subway tubes; and protection of the surrounding property by means of a slurry wall, tied back with inclined anchors into the rock, and later utilized as the exterior basement wall."

References at the end of the book in the Subject index gives indication referenced locations at pages 151, 173, 360 (quoted here), 366 and 367.

Hope this helps.

 

[Dfcmark]

You should contact Mueser Rutledge Consulting engineers. They were the geotechnical engineers for the WTC Slurry wall systems and are currently involved with the remedial work underway Their web site is :

http://www.mrce.com

Mark Montgomery
deep foundations contractors inc.
Thornhill On Canada
mmontgomery@deepfoundations.net

 

The rock under WTC is about 80 feet below grade and consists typical of Manhattan known as Manhattan Schist and Gneiss, a metamorphic rock. The soils overlying rock basically are of glacial origion known as glacial outwash and glacial till, coarse grained hetrogeneous soils. In the upper 30 feet soils may consist of hetrogeneous rubble fill mixed with organic clays and silt typically found in river bottom.Let me know if you need more specific info, perhaps I can help you further.