Final Environmental Asessment, Drainage Ditch and Erosion Control Improvement for the Primary Instrument Runway, Ellsworth Air Force Base, South Dakota.

摘要

In order to meet airfield clear zone requirements (Air Force Manual 32-II23, Volume I, Chapter 3, Task 3.5), the United States Air Force (USAF) proposes to extend an existing stormwater culvert located near the primary instrument runway at Ellsworth Air Force Base (AFB). Currently, there is a stormwater culvert that extends from under the south edge of the Base primary instrument runway and discharges to an open ditch and associated wetlands. The ditch is located in the northern half of Operable Unit I2 (OU-I2). Air Force Manual 32-II23, Volume I, Chapter 3, Task 3.5 states that there needs to be I , 000 feet of level graded area in the airfield clear zone. The existing ditch is approximately 20 feet deep in some areas and could cause damage to aircraft in an emergency landing within the airfield clear zone. The ditch and associated wetlands also attract deer and birds, which pose an animal collision hazard to aircraft using the runway. DESCRIPTION OF THE PROPOSED ACTION. The proposed action would involve adding approximately 850 linear feet of concrete culvert to the existing stormwater culvert that extends from under the south edge of the primary instrument runway and discharges into a drainage ditch and associated wetlands. Once the culvert is installed and connected, the drainage ditch would be backfilled to provide a graded level area in the airfield clear zone. There are no other action alternatives, short of moving the runway or relocating the Base that would bring the base in compliance with airfield clear zone requirements. Fencing and/or Kevlar wire could be placed around and across the wetlands to deny access to the wildlife; however, this would not eliminate clear zone safety issues and was not carried forward for further analysis.