Potentially Acid Producing Rock Encapsulation and Permitting - Case Study for SR-28 (US-127) Landslide Project in Fentress County, Tennessee

摘要

Old coal strip-mining operations in the Upper Cumberland area of Tennessee are known sources of acid drainage which have impaired streams and have negatively affected the environment in Tennessee. A growing awareness among environmental activists and citizens to the potential consequences to potentially acid producing rock have lead to an increased sensitivity and scrutiny of any projects which may disturb or excavate rock formations that can lead to acidic drainage. An awareness of this issue, partially fostered by problems with the Federal Cherahola Skyway project in eastern Tennessee lead the Tennessee Department of Transportation to adopt guidelines for treating and mitigating potentially acid producing rock on project in the early 1990's. These guidelines were recently revised, but old and new guidelines included encapsulation of potentially acid producing rocks in highway embankments. This is an approach that has proved successful on a number of TDOT projects and has prevented acidic drainage caused by roadway construction on TDOT projects.rnThe State Route 28 (US 127) widening project where this encapsulation method was recently used was started as a project because of a landslide which required constant maintenance. The affected section of roadway has required regular (sometimes daily) maintenance in order to maintain traffic since the initial slide. This project was delayed by several years due to permitting issues, questions and hearings partially because of the potentially acid producing shale (from the Fentress Formation) that would be disturbed by the roadway construction. The encapsulation details were revised based on input from citizens, environmental advocacy organizations and the Tennessee Division of Environment and Conservation's Water Pollution Control Division. Construction of the project began in Fall of 2007 and will be complete in 2008.