Air emission monitoring, vapour control and public communications during MGP site excavation in close proximity to neighbours

J.W. Lingle, H. Nehls-Lowe and M. Falk

Abstract

Soil excavation and hauling were conducted on a former manufactured gas plant (MGP) and leaking underground storage tank (LUST) site in close proximity to several apartment/condominium buildings and businesses. In order to minimize potential concerns over site related emissions during remediation, a team was developed consisting of representatives from local and state health agencies, the Wisconsin Department of Natural Resources, city, engineering consultant, and company personnel in order to develop plans for the remediation. A comprehensive public communications program was implemented prior to site excavation activities which included ongoing outreach and feedback with nearby residents and businesses, and addressed temporary parking and voluntary temporary relocation. During soil excavation, ambient air quality was measured through the use of a real-time 7-station perimeter air monitoring system and portable gas chromatography which allowed rapid response to increases in air emissions. Parameters monitored included benzene, toluene, tri-methyl benzene, total xylenes, and respirable dust. Methods were employed to control volatile hydrocarbon emissions such as application of foam, use of a perimeter misting system, covering soil piles with plastic or sand, rapid backfill, minimization of open excavation areas, relocation of work areas, and discontinuing excavation activities during brief periods. Indoor air quality was monitored in the nearest apartment with a portable gas chromatograph during several episodes of increased ambient volatile hydrocarbon concentrations. The excavation project was accomplished with minimal exceedences of short term (15 minute) guideline values, no exceedences of 24-hour guideline val-ues, and no health concerns or complaints from nearby apartment residents or businesses.

Key words:air monitoring. MGP site, odour, public communications, vapour control