(above) Aerial view of TTI's 19-acre erosion control laboratory: (1) compost berm test facility, (2) testing flume, (3) slope protection facility (indoor rainfall simulator), (4) vegetation greenhouse; (above left) indoor rainfall simulator close-up; (above right) compost berm test facility.
The TTI/TxDOT Hydraulics, Sedimentation, and Erosion Control Laboratory (HSECL) provides the transportation industry a uniform and timely testing and research program for products and devices used for storm water quality improvement, erosion, and sediment control. TTI's Environmental Management Program currently operates this full-scale, outdoor evaluation facility for the performance testing of selected erosion control materials. The overall purpose of this facility is to produce and maintain a defensible "Approved Products List" to be used on all Texas Department of Transportation (TxDOT) construction and maintenance activities.
The 30-foot channel flume is used for testing channel-lining materials at high stress flows. The 60-foot soil flume is used to replicate shallow, low-velocity roadside channels. Current research using the soil channel is analyzing compost filter berm characteristics and looking at the chemical composition of the leachate from compost filter berm placement in sheet flow, low-velocity storm water situations. This study is also conducting trials of the berm's structural stability, looking for failure thresholds.
The HSECL greenhouses provide a controlled environment for growing approved seed mixes free from outside contaminants such as weeds. The erosion and sedimentation control materials are tested to determine their ability to establish perennial vegetation cover. The purpose is to understand how materials foster establishment of vegetative cover and how vegetation contributes to the control of surface erosion on slopes and in channels.
The indoor rainfall simulator has two soil beds that can be adjusted to match any desired slope up to 1:2 (or 50 percent). It provides water drop size distribution and impact velocity typical of storms common to Texas and the Gulf Coast regions of the country. The rainfall simulator is designed to subject test beds of selected soils to the largest, most destructive rainfall characteristics. Almost all of the water droplets reach terminal velocity before they hit the soil. Rain is dropped from a height of 14 feet, which causes the speed and erosive force of the water to approximate some of the most severe rainfall properties. This state-of-the art facility has dramatically expanded the research capabilities of the lab.
In 2000 the Texas Department of Transportation (TxDOT) and TTI reevaluated the testing program to determine what changes could be made to decrease the impact of natural climatic variations and at the same time increase the precision of measurements. Based on this evaluation the laboratory and facilities were redesigned and renovated. The revisions removed the influence of most climatic variables by utilizing indoor test beds and greenhouses for work requiring vegetation interactions.
The TxDOT/TTI Hydraulics, Sedimentation, and Erosion Control Laboratory will continue to provide the transportation industry with a uniform and timely testing and research program for products and devices used for storm water quality improvement, erosion, and sediment control. Learn more about requesting testing services at this facility.