Engineering geomorphology at the cutting edge of land disturbance: erosion and sediment control on construction sites

Abstract

Construction site management, traditionally dominated by professional engineers, provides an important opportunity for engineers and geomorphologists to work together in minimizing the environmental impacts of land disturbance. Areas disturbed for construction activity have soil erosion rates from 2 to 40,000 times greater than pre-construction conditions, and are important components of nonpoint source (NPS) pollution that degrades surface water quality. Despite significant local-to-watershed-scale environmental and economic impacts, the lack of an individual economic incentive for land developers to control erosion has limited voluntary adoption of erosion and sediment control measures. However, increased regulatory requirements, combined with efforts to identify and publicize the benefits of erosion control, are increasing the number of construction sites on which erosion control efforts are being implemented. Geomorphologists have the opportunity to play an active role in erosion and sediment control by implementing knowledge of erosion and sedimentation processes and of the variables that effect these processes. Pre-project geomorphological site assessments allow project designers to work around areas with high erosion potential, and to stage and schedule land disturbing activities to minimize erosion potential. Combined engineering and geomorphological analyses can increase the likelihood that streams and drainage channels are stable under altered hydrologic conditions, both during and after land use change, and can be used to design a drainage plan that minimizes surface water flow through disturbed areas. A variety of temporary measures to reduce erosion and to trap sediment on site can be designed and implemented, such as temporary surface covers, silt fence, and sedimentation basins. However, design and implementation of these measures require an understanding of erosion and sedimentation processes, and in many cases incorrect installation and maintenance limit their effectiveness. Regular on-site inspections and training by geomorphologists specializing in erosion control can ensure that measures are being installed and maintained correctly, and allow the inspector to modify the erosion control plan to deal with changing conditions and unanticipated problems. In addition, geomorphologists and engineers can use their combined understanding of erosion processes and construction site realities to develop innovative and practical measures to improve erosion control. Construction site erosion control is a field that relatively few academic geomorphologists have shown an interest in, yet has great potential both in terms of job opportunities and research. It is an area in which morphologists and engineers can work together using their complementary knowledge, both for the development and implementation of erosion control plans; as the basis for developing innovative practices; and for undertaking research on the effectiveness of traditional and new approaches to erosion control.