Soil quality and land capability of reclaimed oil and gas well pads in southern Alberta: long-term legacy effects

Abstract

Since 1963 approximately 100 000 oil and gas well pads have been officially certified as reclaimed in Alberta, yet follow-up monitoring programs have not been established to assure provincial environmental desired outcomes such as equivalent land capability are met at these certified well pads. The Ecological Recovery Monitoring Project was designed to determine long-term recovery of environmental quality at certified, reclaimed oil and gas well pads. Our study used soil data from 25 oil and gas well pads that were certified as reclaimed between 1964 and 2011. The objective of this study was to determine if well pad reclamation had long-term legacy effects on soil parameters and land capability as measured with the land suitability rating system (LSRS). We used multivariate covariance generalized linear models to determine effects of recovery time and reclamation on well pad soil parameters pH, bulk density (Db), total organic carbon (TOC), and electrical conductivity relative to reference soils. We also determined effects of reclamation on capability ratings using the LSRS. We concluded that soil quality and LSRS indices on well pads were lower than references due to adverse effects on pH, Db, and TOC. Long-term legacy effects on cultivated soils are significant and not well aligned with intended provincial outcomes. Further monitoring of reclaimed sites is strongly recommended.