GEO-Instruments Application Notes

The use of this monitoring system provides early warning of any potential settlement or differential movement of tank foundation structures. The near real time data from the system provides priceless insight to plant engineers regarding the in situ conditions of the tank foundations. This information will allow a series of tanks to be reactivated, providing economical, safe storage for high demand fuel oil.

Dredging, next to an existing container ship facility raised concerns about sheet pile cofferdam cells. The port engineer wanted to verify that dredging operations did not affect the existing sheet pile cell load distribution, and specified use of load cells across the sheet joints, closest to the dredging, at the bottom, middle and top of the cell wall. Geo-Instruments provided a solution including weldments providing bearing surfaces for the underwater load cells, and flush mounted data logger/antenna system, which allows unobstructed access to the pier and longshoreman operations.

Construction of a new Ferry Terminal at Pier 79 on Manhattan´s west side required construction just 60 feet above the existing three tubes of the Lincoln tunnel. The Port Authority of NY&NJ and the consulting engineer, Langan Engineering, were concerned about damage to the tunnels during construction; they wanted early warning of potential damage to modify construction procedures. Piezometers, Crackmeters, and Vibration monitoring in the tunnels and vent buildings during pile driving operations were specified to provide this early warning. However, the tunnels were active, and did not lend themselves to traditional manned monitoring stations, due to safety, cost, and logistic considerations.

"Helper" strands were installed on this 1924 vintage suspension bridge to correct main cable slippage. The design engineers wanted to measure long term performance of the new helper suspension strands and saddle anchor strand anchors. Strain gages were specified to be installed on these elements to measure this performance, and the gages will be used to detect future load shedding from the main suspension cable.

A 210ft span in the middle of a 1,000 ft retaining wall collapsed onto a major urban highway, closing the northbound travel lanes with over 41,000 cubic yards of rock, soil and trees. Following the emergency response to stabilize the slump and reopen travel lanes, a long term solution to the wall collapse, was needed. A decision was made to excavate the failed section and rebuild with a Bin Wall, however there were serious concerns regarding the stability of the remaining sections of wall during this process. All parties realized early on that a wall movement early warning system was crucial to the safe execution of this project. Geo-Instruments worked with the project geotechnical engineer to develop an automated monitoring system providing real time monitoring of the remaining walls.

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 it´s 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.

This highway was unable to be closed for reconstruction since this six-lane parkway carries approximately 175,000 vehicles per day through the lower city, and approximately 150,000 vehicles per day through midtown. Thanks to Geo-Instruments near real time monitoring instrumentation and technology, this active highway is currently being monitored during reconstruction to provide an early warning system and ensure the safe passage of these thousands of vehicles.

In November 2008, a barge battling against strong river and tidal currents, laden with over 950 tons, with only 1 foot of clearance between piers, collided into the bridge pier. The collision resulted in damage to the bridge pier, misalignment of the swing span and the inability to close the bridge properly. This created questions about the load capacity of the bridge and its ability to safely support the heavy volume of traffic. This vital link between two communities was closed by the Mass. Highway Engineers due to these public safety concerns. Engineers designed a series of tests to determine the structural integrity and load capacity of the bridge. The test called for GEO-Instruments to install and monitor 6 vertical and 4 horizontal beam sensors, 2 vibration monitors and a lateral load test.