HYDRAULIC FRACTURING OF GLACIO- LACUSTRINE CLAY SOILS FOR THE RECOVERY OF LIQUID NATURAL GAS CONDENSATE CONTAMINATION AT A FORMER GAS PLANT SITE

Approximately 500 m³ (132,000 gallons) of liquid natural gas condensate (LNGC) was delineated in subsurface soils underlying a former gas plant at a remote site in north-central Alberta, Canada. Condensate contamination was in the form of free-phase and dissolved-phase natural gas condensate present in subsurface soils. It is postulated that the condensate originated in a nearby flare pit into which it was discharged during occasional process upsets over its 20 year operational life span. The base of the flare pit was connected to underlying sand layers which facilitated the off-site migration of the condensate underneath an adjacent highway and towards a recreational lake.

A remediation method(s) was required that could hydraulically contain and recover the bulk of the free phase condensate and groundwater, and treat the contaminated groundwater on site in a reasonable time frame (i.e. 5 to 6 years). A conceptual site model was developed which predicted that a conventional pump and treat remedial approach would require over 20 years of operation, due to the inherent limitations of low permeability glaciolacustrine clay soils in which the contaminants resided.

This paper describes how hydraulic fracturing was adapted for an environmental remediation application to dramatically expedite the containment and recovery of LNGC, which resulted in significant cost savings compared to more conventional remedial remedies considered.