GPR & Geotchnical Investigation at Dynegy

Spectra provided a geotechnical investigation and a ground penetrating radar survey for the replacement of a duct bank for a power station.

The existing duct bank had been damaged by settlement related to clay subsoil that rested upon a karst limestone foundation. Several hundred linear feet of new duct bank and new manholes were designed and evaluated.

Subsurface Investigation
Spectra performed a ground penetrating radar investigation over and adjacent to the duct bank to confirm its location and to identify any potential voids near the duct bank.

Geotechnical Investigation
Spectra advanced borings to identify subsurface conditions with an emphasis on a determination of susceptibility to settlement due to the clay subsoil and karst features. Two solutions were provided for the replacement duct and vault structures: the first was to install a combination of end bearing piles driven to bedroom, and the second was to install a slab system to float the imposed loads upon the weak substrata. Spectra evaluated primary and secondary condensation phenomena, with forecasts of settlement rates.