Double the Trouble – Crossing the Sunrail Corridor with a 72-inch Stacked Jack and Bore


janine alexander


Tetra Tech


(321) 388-5178


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Natalie Urick

Double the Trouble – Crossing the Sunrail Corridor with a 72-inch Stacked Jack and Bore


Crossing the narrow and heavily congested Sunrail corridor in downtown Orlando with two large diameter pipes was not feasible until a custom 72-inch stacked jack and bore casing concept was designed. The Orlando Utilities Commission (OUC) and City of Orlando Joint Use project required that OUC’s 24-inch raw water main and 20-inch potable water main be constructed via a trenchless installation under the Sunrail corridor within Highland Avenue in Orlando, Florida; however, the right-of way (ROW) is only 30-feet wide and heavily congested with existing utility facilities. There was insufficient room in the ROW to allow for two parallel trenchless (jack and bore) installations and OUC was facing significant additional costs and excessive installation depths if the mains were both constructed via horizontal directional drilling (HDD). Additionally, OUC did not want air entrapment in their potable water main and thus did not want an HDD method of construction for the rail crossing. Multiple trenchless alternatives were developed using jack and bore and HDD methods of construction, but there were issues with these alternatives including conflicts with existing utilities within the ROW, excessive installation depths, and excessive installation lengths that extended beyond the corridor routing limits. A custom stacked casing concept was ultimately designed by Tetra Tech to overcome these installation challenges. The Florida Department of Environmental Protection (FDEP) was contacted for preliminary approvals of the large diameter raw and potable water main stacked casing concept. With FDEPs buy-in of the concept, a difficult pipeline design that was initially double-trouble was solved with this innovative approach.

Nature of Project:
  • Trenchless Research and Innovation
Trenchless Technology Involved:
  • Auger/Case Boring
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Entry Date:

October 23, 2020