Fenceline Concentration Objectives for Manufactured Gas Site Remedial Actions

Manufactured gas plant

To avoid past community issues associated with remediating manufactured gas plant (MGP) sites under an enclosure, Cardno ChemRisk was asked to develop a risk assessment strategy that could determine when remediation activities needed to be modified to be protective of neighboring residents.

Cardno ChemRisk used federal and state risk assessment guidelines to calculate fenceline air concentration objectives (FCOs) protective of offsite residents and other nearby offsite populations for indicator chemicals typically associated with MGP sites (benzene, naphthalene, and benzo(a)pyrene).  

These FCOs incorporated air dispersion modeling to account for the fate and transport of chemicals in the air between the site and the offsite populations. Fenceline air monitoring data for key chemicals were to be compared to the FCOs during remediation and mitigation measures applied as needed if they were exceeded. 

Cardno ChemRisk built fenceline air concentration objectives – based on federal and state risk assessment guidelines – to monitor remediation activities and determine when they needed to be modified to protect neighbors of a former manufactured gas site. 

Manufactured gas plant