Mid-Atlantic, a leader in innovative approaches to vapor intrusion assessment and control, was recently the first company in North Carolina to successfully implement a vapor intrusion mitigation system (VIMS) using Cupolex – an active ventilated sub-slab system employing patented structural dome components made from recycled non-toxic plastic modular materials. The design/install project was for a VIMS at a Child Development Center in Eastern, North Carolina. The VIMS design was based on the results of two soil gas testing events at the subject property in 2012. The VIMS is currently operating as designed and achieving excellent exhaust flow rates, with uniform vacuum across the entire footprint of the installation. Some of the advantages of Mid-Atlantic’s approach over traditional methods include:
- Elimination of accumulated vapors beneath slab using a minimal blower rating while achieving full influence over entire footprint where installed.
- Replaced the need for fill or gravel to bring the slab level, as well as avoiding costs associated with importing, compacting, and certifying engineered fill.
- Since the design did not require trenching or installation of wells (e.g., digging beneath the existing fill material into potentially contaminated soil), the displaced fill material did not require disposal as a hazardous waste.
- The Cupolex arch design reduced the risk of post construction settlement compared to aggregate/engineered fill material.
- The ventilated void space design avoided pitfalls of traditional vapor extraction methods (e.g., trench/well vent clogging due to fines and moisture).
- The design minimized the number of test probes placed at distance intervals to determine zones of influence that are necessary to evaluate traditional vented systems in gravel.
- The ventilated slab approach was superior to a traditional geomembrane barrier, which can allow vapors to pool beneath a slab and enter at alternate pathway locations (e.g., at loose tape connections and stub protrusions).
- Lower cost due to reduced demand for fill, concrete, steel reinforcement, labor, compaction testing, etc.
- Cupolex is made from recycled material (allows for sustainable/LEED credits) and it is resistant to chlorinated solvents and petroleum constituents.
- Only one small blower and vertical vent riser was necessary (compared to two or more for a traditional system requiring higher rated blower capacities). This resulted in lower long-term energy/O&M costs over time.