Simpson Gumpertz and Heger Engineers New Offices, Saracen Development, Newton, Massachusetts

Raytheon is a household word in most parts of the world because of their innovation in everything from home appliances to navigation and computer systems to weapons and aircraft components. Raytheon started in Cambridge, Massachusetts, in the 1920s, and grew to include a one-million square foot cluster of industrial buildings based in Waltham, Massachusetts. Operations continued at Waltham until the mid-1990s, when Raytheon sold the property for redevelopment What they left was a bonanza of potential office and light manufacturing space in the old, outdated buildings still standing on the site.

It was this vision that led Saracen Development to consider plans to refurbish the buildings and create such an opportunity, not only for potential tenants of the site, but also for the City of Waltham. First, however, the site had to be remediated by cleaning the groundwater and contaminated soils under the complex. Most old industrial sites have the problem of pollution in the underlying ground and waters, as the effects of certain chemicals on peoples' health was not well understood 50 to 70 years ago.

What was left after the remediation was a fairly clean site with some minor amounts of contamination present, particularly under one side of one of the buildings where the prestigious engineering firm of Simpson, Gumpertz and Heger (SGH) were considering making their new offices.

Their requirement was that the 60,000 s.f. proposed office space itself be completely free of any hint of contamination from volatile organic compounds still below the slab. To that end, Saracen hired the appropriate engineers to investigate what could be done to further mitigate these vapors, and Resicon USA was hired to provide a design/build a system that would accommodate SGH's strict demands, but would still be workable in a building where old, cracked concrete, columns supporting the roof, and terracotta walls were juxtaposed.

Resicon's first challenge was to assess the condition of all the elements that made up the foundation of the building and wall/floor transition of the building, then produce a plan that was workable and economical for Saracen.

Resicon designed a lined barrier system that was not physically attached to the edge of the floors by bolts or other fasteners. The concrete of the floors, and particularly that of the base of the walls, was cracked, broken, or degraded in many areas. Resicon realized that not only did the floors need to be sealed with special barrier materials at their many settlement and structural cracks, but the wall/floor transitions had to be treated with fluid applied and moldable materials to even stand a chance of being sealed. These two features would need to work in conjunction with, but be independent of, the HDPE liner that would cover the entire area before the new slab was poured.

Resicon’s years of practical experience with all types of linings and coatings had shown that, in certain conditions, these two elements could be used in conjunction with one another to produce the barrier system needed to keep the VOC’s from infiltrating the working space. Since the types of VOCs under the slab were technically not compatible with the HDPE liner proposed for the work, Resicon flluorinated lining materials to provide the barrier properties needed, but which were still weldable to the general polyethylene lining. These strips would cover all cracks in the floor, using a special 100 percent solids tape to adhere the strip completely to the concrete surrounding the cracks. Additionally, urethane and epoxy caulking and coatings were used to further seal the transition points where columns penetrated the floors, in repaired areas where underslab piping had been installed, and where the exterior walls of the building met the floor.

All new and existing electrical and plumbing penetrations were sealed using Resicon-designed boots. Additionally, Resicon's Couple-All through-liner penetration system was used at all vent openings in the slab and at the eight sampling ports placed throughout the new slab.