Project History: Chicago Elevator Pit

This project history examines dewatering performed for a new elevator pit in an existing basement in Chicago. Locked-Up Storage tried to dewater two feet of water by sumping with no success. Griffin installed sanded wickpoints to a depth of eight feet and ran a discharge hose up a vent shaft to discharge outside of the basement. The vacuum pump fumes were also vented outside via the same shaft, making it a very compact and efficient system.

Locked-Up chose Griffin after their attempt to dewater via sumping did not work. The sumping caused sand movement under the existing floor due to the “sloughing” of material. Griffin’s approach was to install a Modular Vacuum system. The pump parts could be carried to the site with hand trucks and dollies to be assembled in the basement. The ¾-inch tubing was non-intrusive and the header pipe was completely out of the way of the excavation. Electric power was provided so there was no diesel noise or fumes. The oil mist that is inherent with a vacuum system was dispersed by extending the exhaust hose through the air shaft to the outside of the building, which was the same location as the discharge piping.

The loss of soil under the existing floor from the sumping efforts created a more significant risk than the vacuum wickpoint system. If you look closely at the pictures you can see the voids under the existing floor.

Modular wickpoint system setup

Wickpoint Manifold

Wickpoints installed on 3/4″ HDPE tubing

For more information on Griffin’s dewatering methods, read our breakdown on dewatering.