AASHTO's Wetland Manual for Transportation Designers

Abstract

The Oregon Department of Transportation (ODOT) developed the “Guide to Wetland Mitigation Issues for Transportation Designers” for the American Association of State Highway and Transportation Officials (AASHTO), published in September 1996. The manual provides a bridge of understanding between the specialized disciplines of wetland ecology and regulation and highway design. AASHTO recognizes a need to improve understanding and collaboration between highway designers and environmental staff The manual is written in a readable, jargon-free style suited to the non-technical reader. It provides information on wetland functions, policy and regulations, mitigation options, the mitigation site development process and post-construction management. It was based on several years of practical experience gained in each phase of mitigation planning, design construction, planting and monitoring. The manual emphasizes practical options for wetland impacts avoidance and minimization, and sets out a step by step, multi-disciplinary approach to the mitigation site development process. It discusses the special issues relating to contractor selection and coordination, obtaining plant materials, accurate site grading for specific hydrological conditions, soil amendment, and planting techniques and timing. The guide has been applied by ODOT in numerous wetland mitigation sites, including its first mitigation bank at Dalton Lake, the subject of another paper at this conference. Origin and Purpose of Manual The AASHTO “Guide to Wetland Mitigation Issues for Transportation Designers” (“manual”) was developed by the AASHTO Task Force for Environmental Design between 1993 and 1994, and published in September 1996. The staff of Oregon Department of Transportation Environmental Services, under the direction of its manager and task force member Eb Engelmann, took the lead in writing the manual. 1 Senior Wetland Biologist, W&H Pacific, Inc. 8405 SW Nimbus Ave., Beaver-ton, OR 97008 2 Wetland Specialist, ODOT Environ. Services, 1158 Chemeketa St. NE, Salem OR 97310