Project Profile: Colleges Bring Innovation to Fort Benning
Recently the US Army, in an effort to consolidate resources, moved the United States Army Armor School to Fort Benning, GA. The maneuvering of its numerous tracked vehicles, which can weigh as much as 75 tons each, disturbs large areas of vegetation, loosening the soil and exposing it to erosion with the next rainfall.
Fort Benning is located in two basic soil provinces, the Georgia Sand Hills and the Southern Coastal Plains. The Georgia Sand Hills are a narrow belt of deep sandy soils with rolling hilly topography. These soils consist primarily of marine sand, loams, and clays deposited over acid crystalline and metamorphic rocks. The Southern Coastal Plains, which is where most of the armored training maneuvers are to occur, has a topography divided into nearly level to rolling valleys and gently sloping to steep uplands. The soils in this area contain a loamy or sandy surface layer with loamy or clayey subsoils.
The maneuvering of Ft. Benning’s numerous tracked vehicles can disturb large areas of vegetation, loosening the soil and exposing it to erosion.
It is this Southern Coastal Plains area that is most susceptible to erosion, as evidenced by Georgia’s Providence Canyon State Park, located only a few miles away. The 1,000-acre canyon, with massive gullies as deep as 150 feet, was caused by poor farming practices during the late 1800s. Fort Benning, in addition to hiring experts in soil erosion and sediment control to develop plans for implementing best management practices to avoid creating a similar problem in these maneuver training areas, solicited the assistance of senior students from the University of Georgia at Athens (UGA) and Auburn University (AU) to develop innovative yet cost-effective plans for controlling sediment along the tracked vehicle trails that connect the various maneuver areas.
The Student Design Teams
The students from each university took on this work as their senior design project and formed design teams. The team members for the UGA design team were Jake Dungan, Chris Mongrue, Jason Morris, Carrie Nearhood, Nick Sopchak, Joseph Trotochaud, Sam Webb, and Dr. Mark Risse, their student advisor. The AU team members were Jesse Godwin, Jessica Mills, Ramsey Phillips, and Dr. Mark Dougherty, their student advisor. The following Fort Benning staff provided guidance and geographic data to these teams: Jay Howell, strategic planner; Terry Jones, 2-16th cavalry training specialist; Richard Wright, training area custodian; Randel Lemoine, P.E., civil engineer; and Hugh Westbury, watershed manager. The design teams met regularly with Fort Benning staff to obtain information, to show the design progress, and to discuss alternative designs. Within about a three-month period, the student teams were able to take their projects from the initial defining of the scope of work through the submission of final designs and recommendations to giving a project briefing before commanding officers at Fort Benning.
The AU team used Water Erosion Prediction Project, a runoff and soil erosion modeling program, to strategically locate sediment management practices such as rolling dips, contour infiltration trenches, channel reinforcement, and check dams. The team also used the program to predict the average annual sediment loading to adequately size and space these practices.
The UGA team proposed four sediment control practices: rolling dips, linear retention-infiltration basins, hardened (reinforced) stream crossings, and compost filter berms. The team used the more traditional Revised Universal Soil Loss Equation 2 (RUSLE2) developed by the Natural Resources Conservation Service to size these practices. Team members also investigated using timber mats reinforced with steel plates to create a bridge for crossing shallow streams. They determined that the reinforced timber mats provide a simple, cost-effective solution for crossing these shallow streams with minimum environmental impact.
Runoff volume reduction was a key element in protecting the integrity of the nearby streams. The armored training maneuvers can disturb large areas of vegetation, resulting in increased runoff. This increased runoff volume causes streambed incising and bank erosion, which can result in the creation of deep gullies similar to those in Providence Canyon. Standard sediment basins concentrate runoff into relatively small basins, which do little to reduce the runoff volume.
Both teams investigated a design practice they called either infiltration swales or linear sediment basins. This practice involved cutting long trenches with a shallow gradient that followed along a contour elevation, much like a hillside terrace. These linear practices are able to capture the sediment and significantly reduce the volume of runoff discharged into nearby streams.
Both teams designed the sediment control practices to have sufficient capacity for at least a five-year cleaning/maintenance cycle. The linear basins had much longer maintenance cycles because of their dual purpose of sediment and runoff volume control and their design to disperse the sediment and runoff over larger areas rather than concentrating it into a small basin. The sediment removal and disposal process for the linear basin is simple, involving the running of a bulldozer with an angled blade along the bottom of the basin and rolling the sediment onto the downslope berm. The result is a low-tech, extremely cost-effective sediment control practice.
ConclusionThe synergistic cooperation between the Fort Benning Maneuver Center of Excellence and the student design teams from these two universities created benefits for all. The students were able to enhance their engineering education with real-world problem-solving experience, and Fort Benning received some very innovative and cost-effective solutions that are in the process of being implemented.
