Instrumentation and Monitoring

A detailed plan for monitoring possible ground surface movements caused by the microtunneling operations should be prepared. The plan is typically prepared by the engineer in consultation with potentially affected facility owners, as described in Section 13.5. The plan should address the equipment, method, and frequency of survey measurements. The engineer should identify special monitoring requirements. A baseline survey needs to be conducted before the start of construction sufficiently early to establish preexisting conditions. In addition to baseline surveys, before construction the contractor should document existing conditions of potentially affected structures, utilities, and facilities. The documentation of existing conditions establishes a baseline against which damage claims can be evaluated. Before the installation of instrumentation, the contractor should meet with the engineer to discuss frequency and formatting of reports as well as action levels and contingency plans.