The Site Inspectors

Nearly 12 years after the devastation of 9/11, the city of New York has made substantial progress in reconstructing the World Trade Center site. The Port Authority of New York & New Jersey wants to make sure the new buildings continue to go up smoothly, so it has hired Tectonic Engineering & Surveying Consultants PC. The firm performs controlled inspections and testing of earthwork, foundations, concrete, masonry, structured steel, fireproofing, etc., and it’s now overseeing the construction of World Trade Center towers 1 and 4.

“The whole idea of the special inspections and third-party testing,” company president and CEO Donald Benvie says, “is to perform Quality Assurance/Quality Control [QA/QC] monitoring and oversight of the construction project to ensure it meets … building-code requirements as well as the design plans and specifications.”

To perform special inspections and materials testing that meets the requirements of the various regulatory codes governing QA/QC activities, Tectonic relies on a variety of tools and equipment. “The most important tool is the knowledge and visual observation—or, the eyes—of the inspector,” Benvie says. Tectonic employs experienced professionals who have the necessary training, certification, and experience—and who are also familiar with the construction process and the methods and materials used during its course.

The firm also does substantial testing off-site, but this comes later. “The testing aspect of the work, confirmed and supported with the actual numerical results of the testing process, verifies the visual observations in the field,” Benvie says.

Inspections of concrete, structural steel, and a building’s foundation are among the most important in a materials-testing firm’s work. And inspection of each of these materials comes with its own set of specifics.

Before the concrete is placed, Tectonic double checks the reinforcing rebar to ensure its location, spacing, and size comply with design plans and fabrication drawings. The firm then conducts various on-site field tests, including air entrainment, microwave testing to determine the concrete’s moisture content, and slump testing and casting of concrete cylinders, which are taken to the laboratory to check for compressive strength. Periodically, inspections are also made at the concrete batch plant to verify the batching procedures.

Structural-steel inspection also involves both field and lab inspection. “In addition to the building code and design plan and specifications,” Benvie says, “the most important part of the field inspector’s work is to verify the sizing of the steel members and make sure the connections between the steel pieces are done properly. This is verified by focusing on the welding and bolting of the connections.”

During earthwork, including excavating and the preparation of a project’s foundation, Tectonic confirms the removal of all weak or soft subsoil materials that would negatively impact structural support. “Part of the inspector’s role is to visually assess the final excavation level and make sure the foundation subgrade is competent,” Benvie says. Other responsibilities during the earthwork phase of the project may include pile-driving inspection and compaction testing of backfill.

While Benvie acknowledges “a process is a process,” he admits the magnitude of a project such as World Trade Center towers 1 and 4 requires a greater level of effort and expertise. “You are inspecting the same elements,” he says, “but you are inspecting them on a much larger scale.” Additionally, he notes that greater coordination is required because of the work being done on infrastructure and other support facilities below the buildings.

Demand for special, controlled inspection and materials testing is rising. Benvie says what once was a secondary consideration in the construction process is getting more attention as project owners and public agencies realize the cost value of implementing strong QA/QC programs. “The lifecycle cost of a structure,” he says, “is influenced by the quality—or lack of quality—of the work during the construction process.” ABQ