Tectonic is providing geotechnical engineering, construction inspection and materials testing services for the $4.4 billion construction of the Second Ave, Subway running tunnels and the 86th St. Station cavern mining and heavy civil. The work involves excavation of two station caverns, each approximately 900LF long by about 70FT high and almost 100FT wide and excavation of two 22ft. diameter running tunnels between 92nd St. and 63rd St. (approximately 7200LF each). Construction of the new running tunnels and station involves extensive rock excavation using conventional drill and blast methods and tunnel boring machines (TBM’s) to carve out the caverns to accommodate the new station. Ancillary work involves the installation of drilled shafts, rock anchors, rock bolts and shotcrete to support the excavated faces.
As agent to MTA, Tectonic is a sub consultant to the joint venture contractor, Skanska Traylor JV, responsible for performing geotechnical special inspections and third party materials laboratory testing. Compaction testing and back fill placement included gradation analysis, Atterberg limits, density, and moisture content. Responsibilities include blast and vibration monitoring, review of vibration mitigation plans, geologic mapping of excavated faces, inspection of rock reinforcement including rock bolts and passive dowels, inspection of subgrades, witnessing and monitoring of rock anchor testing including water pressure testing of anchor boreholes, inspection of rock drains, inspection of final shotcrete placement, underpinning, boring inspection, and logging of exploratory probe holes ahead of TBM. Tectonic is also providing special inspections, laboratory testing and QA/QC services during the excavation for the tunnels and caverns, dewatering, tunnel lining and construction of structures involving field and plant inspection and testing of concrete, shotcrete, structural steel, masonry, grouting, fireproofing, mechanical/ventilation systems and electrical systems, etc. Tectonic is also responsible for development of shotcrete qualifications testing program including preparation of design mixes and performance of laboratory and field trial tests. Other duties include preparation of daily, weekly and monthly inspection reports, attendance at progress meetings and liaison with onsite MTA representatives.