AASHTO HDG CHAPTER 12

Abstract

INTRODUCTION: Storm drainage, which now includes stormwater management facilities, is an integral and expensive aspect of highway design, highway construction and, all too often forgotten, highway maintenance. This chapter provides an overview of the concepts and practices of this challenging aspect of highway drainage. <br>The purpose of this chapter is to acquaint the hydraulics engineer with the principles and practices of stormwater management as they relate to transportation facilities. This Chapter provides a brief review of the current and ever-changing maze of regulations and a discussion of the potential impacts of unmanaged runoff on downstream properties and ecosystems. A large section of the chapter is allotted to the development and implementation of an effective stormwater management program including the application, design, construction and maintenance of Best Management Practices (BMPs). This chapter also offers some insight into the future of stormwater management and provides a list of reference materials. <br>A stormwater management program should involve a comprehensive approach to both water quantity and quality. Practices, which are adopted in the areas of operations and maintenance, such as salt containment and reduced pesticide/herbicide usage, can have significant benefits to the environment. Construction practices, which stage grading operations and reduce sediment loads, are also important to the overall management program. This chapter, however, will focus on the use of permanent structural controls to reduce surface water flood hazards and environmental impacts resulting from highway facilities. Information on temporary controls suited to manage runoff during construction can be found in Chapter 3.