Tectonic is providing geotechnical and special inspection/materials testing services for the $1.1 Billion construction of the No. 7 Line running tunnels, Site A Vent Building, Site J Vent Building and furnishing and installing systems and finishes for the new expansion. The project involves the construction of 7,000FT of two 22FT diameter running tunnels, and the construction of two new subway stations at Tenth Avenue/41st Street and 34th Street/11th Avenue near the Hudson Yard on the West Side of Manhattan. 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. Other aspects of the work includes complete above and below grade construction of the Sites A & J Vent Buildings and installation of all the systems and finishes including trackwork and signalization, escalators, elevators, etc.
As representative for MTA, Tectonic is a sub consultant to the joint venture contractor, Skanska Railworks JV, responsible for performing geotechnical special inspections and third party materials laboratory testing. 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.
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. Compaction testing and back fill placement included gradation analysis, Atterberg limits, density, and moisture content. 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.