Installing a 24-Inch Pipeline Beneath an Interstate Highway and Regional Aqueduct using HDD

Construction of transportation infrastructure often involves resolving conflicts between intersecting transportation modes. Trenchless technologies allow for construction of buried structures with minimal disruption to surface transportation systems. This paper describes the use of horizontal directional drilling (HDD) to construct a 24-inch diameter natural gas transmission pipeline beneath an interstate highway and regional aqueduct. Prior to construction a hydraulic fracturing analysis was performed to evaluate the potential impact of pipeline construction on existing surface structures. During construction, quality assurance observation and testing was performed to evaluate compliance with permit conditions and good drilling practices. After construction was completed, a mass balance calculation was performed to estimate the amount of solids in the slurry remaining in the annulus around the installed pipeline. Results of the mass balance calculation suggested that the slurry remaining in the borehole was substantially heavier than the slurry that flowed out of the borehole during construction.