Bencor utilized several geotechnical construction techniques to facilitate construction of an underground storage tank.

The Project

The County of Onondaga NY Department of Public Works needed an underground tank to capture and store sewage during high water flow events before treatment and release.

The Solution

Bencor installed a 150 foot diameter reinforced circular diaphragm wall to a depth of 85 feet to construct the below ground tank structure. In addition, a 45 foot thick 160 foot diameter area beneath the bottom of the slurry wall was grouted to minimize water inflow as the tank was constructed. In all, 322 holes were drilled to depths below grade of 119 feet and cased thru 74 feet of overburden. The holes were upstage grouted using balanced stable cement grouts. Bencor’s ultimate grout control was used for real-time monitoring of the flow and pressure. Sonic drilling was also used. Scope also included installation of 169 tiedowns from the bottom of the completed structure to resist hydrostatic uplift forces.

Project Facts


County of Onondaga NY, Department of Public Works

Main Contractor(s)

C. O. Falter Construction Company

Keller Business Unit(s)



Brierly Associates