As per Chapter 33, Section 3309.4.4 of the New York City Building Code; Monitoring is required during the course of excavation work the Buildings that are within a distance from the edge of excavation that is equal to or less than the maximum depth of the excavation and historic structures that are contiguous or within a lateral distance of 90 feet from the edge of the lot where an excavation is occurring.
Optical monitoring or settlement monitoring can be completed with a Total Station operated by a Big Apple Group technician. In some cases, a Robotic Total Station is provided; both of them provide a calculated and analytical approach to determine structural documentation and potential change during critical construction activities. This report is sometimes referred to as a Total Station Survey. Optical Monitoring entails the installation of optical monitoring devices (prisms, or prismatic sheets) on the structures in question, and a periodic measurement of the location of the devices on the structure with a calibrated survey instrument. The Big Apple Group provides optical monitoring during each phase of construction.
Collection and reviewing this data helps the monitoring consultant and engineer evaluate the performance of the specified construction project, allowing for advanced warning and implementation of corrective measures to be completed, if needed, prior to any catastrophic failures.