PROTECTING LAKE TAHOE USING SOIL FREEZE TECHNOLOGY TO CONSTRUCT A SEWER PUMP STATION IN CONTAMINATED GROUNDWATER

The Tahoe City Public Utility District (District) has been attempting to replace an aging sanitary sewer pump station for the last fifteen years. The new pump station site was selected and the design of the project completed. The Harbor Master Pump Station (HMPS) was sited within thirty feet (2.15 meters(m)) of Lake Tahoe and on a piece of property in an area of heavily contaminated soil and groundwater. After construction started it became very apparent, since the groundwater level is only two feet (0.61 m)) below ground surface (bgs), that implementation of standard groundwater dewatering techniques for a twenty-five foot (7.62 m) deep excavation was not a viable option. The project team regrouped and proposed a soil freeze technology system to assist in the stabilization of the excavation site and reduce any potential concerns for contaminated groundwater disposal.