Horizontal soil vapour extraction : subsurface remedial technology research and demonstration program - pilot test summary report

A subsurface remediation technique for groundwater and soil contamination at the Gulf Strachan sour gas plant in Alberta, was discussed. The site is contaminated by free phase and dissolved phase hydrocarbons due to natural gas condensate releases in the unsaturated zone. The remediation technologies implemented are soil vapour extraction (SVE) and bioventing. This report described how a horizontal SVE system performed in removing volatile organic contaminants through volatilization and biodegradation. Hydrocarbon mass removal through volatilization and biodegradation was monitored by recording off-gas concentrations of volatile hydrocarbons, O2 and CO2. The mass removal rate due to volatilization (20 to 60 kg/day) was moderate compared to vertical well extraction rates, while the mass removal rate due to biodegradation (230 kg/day) was equivalent to vertical SVE mass removal rates. The cost of the SVE trench well was equivalent to two vertical wells. Results of a one month field test indicated that the shallow SVE horizontal trench well showed good promise for removing volatile and biodegradable hydrocarbons from the unsaturated zone. 9 refs., tabs., figs