WASHINGTON AVENUE TUNNEL: FORTIFYING AGING UNDERGROUND INFRASTRUCTURE-Paper

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The Washington Avenue tunnel in Kingston, New York, was built in 1912 to carry storm water and sewage. Most of the tunnel runs through bedrock, but an approximately 170-foot section passes through soil and is lined with a brick arch. Decades later, repeated subsidence and sinkholes developed above this section, forcing the street to close. Inspections found a breach in the tunnel crown, soil inside the tunnel, and seepage near a storm-water shaft. Investigations also identified loosened soil above the tunnel, consistent with ground loss.<br /><br />Remediation used two complementary ground-improvement methods. Vibrating pile probes densified loose sandy soils in the upper 40 feet. A total of 114 probes were installed; the work induced approximately 14–16 inches of settlement in the treatment area, while measured vibration levels remained below the project’s limit for protecting nearby homes.<br /><br />For the deeper, layered silts, crews used jet grouting to create a continuous soilcrete arch over and alongside the tunnel, extending to rock or competent glacial till. The arch comprised 326 overlapping columns and spanned the soil tunnel section, including its transitions to bedrock. Testing showed an average compressive strength above 700 psi, exceeding the 130-psi design minimum.<br /><br />Completed in 2015, the remediation was intended to reduce seepage and soil migration and protect the aging tunnel from overburden pressure. Washington Avenue reopened to traffic after a three-year closure.

Keywords

Washington Avenue tunnel

Kingston New York

storm water and sewage

subsidence and sinkholes

brick arch tunnel

ground loss

vibrating pile probes

jet grouting

soilcrete arch

tunnel remediation