Applying Dynamic Controls to Vapor Intrusion Mitigation Systems to Manage Pressure Differentials, Effluent Concentrations and Energy Conservation

摘要

This paper describes the development and applications of dynamic motor controls that have been designed to optimize the operational efficiencies of soil vapor intrusion mitigation systems (VIMS). The current generation of VIMS utilizes a combination of centrifugal, regenerative and radial blowers that are intended to achieve minimum sub slab pressure differentials that are usually specified by a regulatory agency's vapor mitigation guidance documents. Among the limitations of current technology is that after the blowers have been running for a few weeks, the soil moisture beneath the slab is reduced which often results in several adverse unintended consequences. They are: the development of preferential pathways that can draw source contaminants through the system thus exceeding exhaust effluent standards, the development of zones of excessive soil gas airflow yields and the creation of sub slab vacuum fields that exceed the pressure differentials that are required to mitigate the entrainment of soil vapors. All of these factors contribute to excessive power consumption. The paper demonstrates how the application of sensors and reactive circuitry can be implemented to achieve specified sub slab pressure differentials for the purpose of regulating the flow of source contaminants, exhaust effluent concentrations and improving energy conservation by as much as forty percent or more. Dynamic Controls and the associated electronic system management technology is a substantial improvement over the current technology in the areas of monitoring motor performance, reducing energy consumption, extending operating cost savings to building owners and providing system managers with advanced warning of potential motor failures thus protecting building occupants from unnecessary exposure to harmful vapors.