GEO-Instruments Application Notes

This sewer line, built in the mid 1920´s, has experienced heavy corrosion at some places, and is in need of rehabilitation. The project includes rehabilitating approximately 30,000 linear feet of the semielliptical outfall sewer, and compaction grouting of the soil strata above the tunnel for approximately 5,800 linear feet to prevent surface ground settlement over the tunnel. LNOS uses 3 total stations reading approximately 70 glass prisms, read with IRIS remote control software via wires IP connections, in real time, to control compensation grouting by monitoring the heave/settlement at structures on the surface.

New York´s MTA´s East Side Access project will connect the Long Island Rail Road´s (LIRR) Main and Port Washington lines in Queens to a new LIRR terminal beneath Grand Central Terminal in Manhattan. The project requires tunneling across the upper east side of Manhattan Island in New York and down Park Avenue to the existing Grand Central Terminal. In order to monitor the effect of the tunneling operations on existing high value real estate above the tunnel, the project designers specified traditional multiple position borehole extensometers (MPBX) for tunnel alignment cross sections.

A deep excavation at Dulles International Airport was needed in order to build a new terminal related infrastructure, and to facilitate tunneling operations connecting to the main terminal. In order to allow safe construction to continue inside the excavation, Airport management required that the support of the excavation system, be monitored for movements with In Place Inclinometers.
Geo-Instruments supplied over 450 vertical IPI sensors, installed in over 40 inclinometer casings, connected to 6 remote dataloggers. Data is collected for the loggers hourly by a Geo-Instruments server, processed and displayed on a project web site for the concerned parties to view. Real time e-mail alarms can also be accommodated in this system.

Geo-Instruments was contracted for the Ulink I-5 undercrossing project: U215. The U215 Contract is part of a larger plan that will eventually link the University of Washington to SeaTac airport, through downtown Seattle. U215 involves tunneling under inter-state I-5, a major artery in Seattle. I-5 was constructed in the early 1960´s and retaining structures supporting road cuts through the Seattle hills are critical to public safety. Enhanced systems were proposed and installed by Geo-Instruments. In turn, Geo-Instruments had the duel honor of being the first to install an automated pulsed laser scan for near real time structural monitoring in the world, and the first WiSe wireless sensor network in North America.

Old South Church is a national historic landmark. It was built in 1873 and is home to one of the oldest religious communities in the country; however this Venetian Gothic style church has sustained large cracks recently in its east wall. The damage to the wall was the result of the excavation work taking place to install an elevator for handicapped access to the subway station. During the high pressure jet-grouting operations some of the wooden piles supporting the structure shifted, triggering a 60´-70´ large crack from the foundation to the roof, ranging from a hairline to a 1" wide crack. This crack caused safety concerns and Geo-Instruments mobilized within 24 hrs to join the team of engineers assessing the damage.