F acility M anagement
Real Estate Journal — Owners, Developers & Managers — July 31 - August 13, 2015 — 21B
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M id A tlantic
By Richard Arnold, PE, PG, EWMA Customization of vapor intrusion control solutions
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ignificant increases in practitioner skill level and experience and the
used for the collection portion of the vapor intrusion control system should be compatible with the planned load trans- fer platform materials. This will essentially eliminate some ground improvement design issues, minimize any concerns about pipe embed- ment depths, and perhaps even eliminate the need to import additional materials for installation of the collec- tion system because the load transfer platform materials already have been procured. Another example is elimi- nating the need for use of a specialized synthetic liner by installing a slightly upgraded standard vapor barrier sys- tem beneath a ground floor slab. This might be made feasible and may be eas- ily implemented by installa- tion of a pneumatic barrier directly beneath the vapor barrier to provide additional barrier protection against intrusion, and additional protection against degrada- tion of the standard vapor barrier by potentially ag- gressive contaminant vapors. Additional benefits of this approach will be the reduction of quality control concerns associated with installation of specialized synthetic liners by trades without long-term liner installation experience, and reduction of the number of specialized design features that must be addressed in the development plans and specifications. Existing Buildings -Given the improvements in construc- tionmethods and materials that have taken place over the years, the as-built quality and condition of concrete ground floor slabs, existing vapor barriers, foundation systems and wall systems can be very good. As a result, when deal- ing with existing buildings, it is often being found feasible with minimal augmentation to rely on the existing systems for vapor intrusion control. In this way, the need for ex- pensive specialized synthetic liners and seal systems or sophisticated pneumatic con- trol systems is being gradu-
ally minimized and limited to facilities that truly require high-end systems to provide rigorous control of hazardous or toxic gases. For example, consider a generally sound ground floor slab, constructed with a suit- able design mix under con- trolled concrete installation conditions. Cracks in the slab may have developed for many reasons, resulting in vapor in- trusion to the building. How- ever, if the top of the slab is exposed and is or can be made accessible, it may be practical to repair the cracks in the slab and completely seal it with low-VOC or no-VOC sealants that are compatible with con- crete, inexpensive, readily available and easily applied by skilled tradespeople or environmental technicians. This approach can and has resulted in significant cost savings to building owners who are challenged by vapor intrusion issues in their exist- ing buildings. In addition, practitioners are designing a wide range of systems to supplement the partial barrier features of existing buildings with ad- ditional barrier technologies that often include creative pneumatic barriers. For ex- ample, for an existing build- ing that has been constructed with air permeable materials beneath its ground floor slab, it may be relatively easy to penetrate the building frost walls with extraction ports, install simple conveyances exterior to the building, in- stall a highquality stack at the back of the building where it is not obtrusive and mount a rotary wind turbine on the stack. This approach can provide a green, sustainable, vapor intrusion control mechanism that requires essentially no maintenance, no down- stream expenditure and can meet all of the necessary regulatory requirements for vapor intrusion control. Risk Management and Value Engineering -Risk- based value-engineered so- lutions are often practical
i n c r e a s e d availability o f spec i a l - ized products have resulted in many in- novative and customized solutions for addressing
Richard Arnold
the vapor intrusion needs of developers, businesspeople and attorneys. This is espe- cially true in three specific areas of practice-new build- ings, existing buildings, and risk management and value engineering. New Buildings -It is criti- cal to integrate any new vapor intrusion system design into existing or planned building systems. This increases the efficiency of vapor intrusion systems, while lowering the installation costs and miru- mizing both the impacts on construction schedules and the downstream operating and maintenance costs. The typical challenges are integrating the system with existing or planned founda- tion systems, vapor barriers, ground floor slabs and exte- rior features (e.g., walls, roofs, and ground features), while at the same time ensuring that the components of the vapor intrusion control system will be accessible for maintenance and repair. Some of the inte- gration steps include deter- mining the types, locations and elevations of process and monitoring piping, ground floor slabs, vapor barriers and foundation systems; and adjusting the types, locations and elevations of needed va- por intrusion control utilities to conform to the building components and be construct- ible within the overall project constmction plan. One example of integration with building systems is the use of a planned ground- improved foundation system using load transfer, platform- controlled modulus column technology. If possible, the selection of materials to be
for planned new buildings, where the beneficial man- agement of scale issues and capitalization is critical. In such situations, practitioners more frequently are consider- ing the usefulness of physi- cal and pneumatic building features such as high-quality concrete slabs and flexible HVAC systems; examin- ing the utility of Johnson & Ettinger vapor intrusion modeling variants and other numerical tools; finding a means to design hybrid in- stallations whose character- istics vary across a building area; and more frequently bringing pilot testing tech- niques and critical analysis into the design process. An example of this process is in vapor intrusion control design for warehouse develop- ment, where the scale can be very large and capitalization can be crucial. In such instal- lations, it may very well be practical to provide active protection over portions of the
planned building area; less expensive passive protection over other areas and inex- pensive contingent protection where intrusion potential is low; and flexible HYAC sys- tems in tandem with slightly upgraded floor slab designs may be sufficient to provide a reasonable level of protection. The use of customized vapor intrusion control systems is on the rise, and developers, businesspeople, and attorneys are reaping the benetits. This customization is resulting in the development of more effective vapor intrusion con- trol designs that are more responsive to individual build- ing characteristics, easier to install and, in general, are reducing the cost of vapor intrusion control system in- stallations. Richard Arnold, PE, PG, is EWMA's director of En- gineering & Remedial Ac- tion Services. He is based in the firm's headquarters' pffice in Parsippany, NJ. n
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