Engineers study how contaminated soil can be drained, utilized

LCS research published in Geosynthetics International

Each year, 400 million cubic yards of soil are dredged from water bodies in the United States alone. Much of this byproduct is contaminated, deemed unusable and put into landfills. Mahmoud M. Khachan, Shobha K. Bhatia and Jennifer L. Smith are working to answer the question of how the soil can be drained and utilized.

A technical paper, “Retention performance of woven geotextiles subjected to cyclic flow conditions” by Khachan, Bhatia and Smith, was recently published in Geosynthetics International. The paper discusses research taking place in Syracuse University’s L.C. Smith College of Engineering and Computer Science (LCS).

Khachan is a doctoral candidate in LCS; Bhatia is a professor of civil and environmental engineering in LCS; and Smith is an assistant professor at the SUNY College of Environmental Science and Forestry.

There are thousands of types of geotextiles (plastics) used on roads, retaining walls, levees, landfills and lakes that serve to contain and reinforce soil. Each contains its own properties (such as weave patterns and fibers). The research performed by Bhatia, Khachan and Smith focuses on the retention performance of specific woven geotextiles used for these purposes. Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect or drain. They come in three basic forms: woven, needle punched or heat bonded.

The geotextiles, selected based on use and application, were subjected to cyclic flow conditions in which water ran in and out similar to a tide flow. Cylinders were used to simulate a cyclic flow system. The study also tested different types of sands commonly found near water bodies.

The developments being made through this research are relatively simple and can be used to address dredge sediments from water bodies. Practical use of these geotextiles includes sand dune armoring to protect upland coastal property from storms, waves and floods. Industrial waste, often found in water bodies such as lakes and rivers, can be dewatered using a geotextiles tube dewatering system.

The study was supported by the Geosynthetic Institute (GSI) fellowship provided to Khachan, who is studying geotextiles.

“Our students are doing truly innovative things,” says Bhatia, professor and former chair in the Department of Civil and Environmental Engineering. The structure of various constructions, such as levees, would fail if the soil was not retained when water seeps through them.

“In the academic setting, we plant the seeds,” says Bhatia. “They grow in the industry where our students develop their ideas into technologies.”

This study will allow for the development of design criteria for choosing the right geotextiles and equipment when building waterway structures. The participants are also beginning to explore the use of starches to dewater soil.

Bhatia is funded by the National Science Foundation (NSF) to do more extensive research on geotextiles. This year, she will be taking a lead role in organizing an international conference, “Geosynthetics 2013,” where several of her students will be presenting their research. Bhatia’s research efforts have focused on the application of geosynthetics and natural materials in waste containment, road and retaining walls and erosion control. She has also served as the vice president of the North American Geosynthetics Society (NAGS).