Chemical amendment of excavated trench material for sustainable reuse

The Integrated Pipeline (IPL) project which involves a 147 mile pipe line is a joint effort between the Tarrant Regional Water District (TRWD) and Dallas Water Utilities (DWU) that will bring additional water supplies to the Dallas/Fort Worth metroplex. As a part of the pipe line layout and construction, large amounts of soil will be excavated during the pipeline construction installation process. Similarly, large amounts of soil need to be imported for bedding and backfilling of the trench. Importing new fill material and exporting excavated trench material for landfilling will have serious implications on both economic and environmental aspects of this mega construction project. As a result, a research study was initiated to study the reuse potential of the native soils as pipe backfill material. It was observed that a large portion of the native soils along the pipeline alignment could not be reused in their native form. Hence, chemical amendment studies were conducted to evaluate the possible reuse of chemically amended native materials. Sustainability concepts such as Economic and Environmental impacts of such reuse methods are discussed in this paper. Both cost benefits and environmental benefits of using ameliorated native soil vs. imported material for bedding and backfilling are discussed in this paper. This study shows that there are considerable cost advantages and environmental benefits in using chemically modified native excavated soils as bedding and haunch material.