Infrastructure and Structural Engineering (Structural Engineering): Misawa AB, Japan

Engineering Design Support for Demolition of the FLR 9 Antenna Array (“Elephant Cage”), Misawa AB, Japan
FLR 9 Antenna Array (“Elephant Cage”), Misawa AB, JapanOTIE delivered a design package for demolition of the Cold War-era, obsolete FLR-9 Antenna Array (called the “Elephant Cage”). This included structural engineering services for a qualitative structural survey of the 1,400 foot diameter Elephant Cage and related structures at a 40-acre complex on Misawa AB. OTIE conducted field investigations with structural and topographic surveys to develop design data, as well as preparing contract plans and specifications, detailed cost estimates, and construction schedules.In preparation for demolition design, OTIE evaluated the structural layout and current condition, identified potential demolition hazards, and inventoried materials for detailed cost estimating.

OTIE’s final design included plans and specifications for abatement and demolition of 142 antenna towers; over 1,500 pilings; two large steel and wood antenna support structures reaching 120 feet in height; a 5,000 square-foot concrete building; a 1,000 foot-long concrete tunnel; miles of coaxial cabling and communication lines; 7 transformers; and multiple vaults. The design incorporated sustainable elements including maximizing material salvage and recycling, and minimizing surface disturbance to maintain vegetation, and reduce the potential for sediment runoff.

OTIE also conducted a Hazardous Building Material (HBM) Survey to evaluate hazardous building materials in and around the facilities to be demolished. In the HBM survey, OTIE focused on asbestos, lead-based paint, PCBs, mercury, and other potential hazardous materials.

Client Name: AFCEC

Location: Misawa AB, Japan

Contract Value: $299,985

Project Features:

  • Demolition design of a unique, complex structure
  • Demolition design included phased disassembly
  • Hazardous Building Survey to identify waste management requirements