A case study of sub-slab depressurization for a building located over VOC-contaminated ground

A sub-slab depressurization system for protecting indoor air quality in buildings located over VOC-contaminated ground is described. Included in the design is a means of assessing the performance of the protection measures during the lifetime of the building. A case study is presented of the sub-slab depressurization system implemented in two renovated historic buildings located at the site of an old gas works facility with extensive tar and PAH contamination in the soil. Measurements of under pressure under the slab and airflow rates in the sub-floor exhaust ventilation ducts from performance checks both immediately after the systems were installed and then 2 years later demonstrated that the protection measures in each building functioned as planned. VOC measurements in indoor air in the buildings during the two performance checks suggested that the air quality in the buildings was not adversely affected by the contamination in the soil.