Integrated technologies for expedited soil and groundwater remediation

A fast-track and economic approach was necessary to meet the needs of a property transfer agreement and to minimize impact to future usage of a site in the Los Angeles Basin. Woodward-Clyde responded by implementing site investigation, remedial action plan preparation for soil and groundwater, and selection and installation of remedial alternatives in an aggressive schedule of overlapped tasks. Assessment of soil and groundwater was conducted at the site, followed by design and construction of remediation systems. This phase of activity was completed within 2 years. Soil and groundwater were found to be impacted by chlorinated solvents and petroleum hydrocarbons. A vapor extraction system (2,000 scfm capacity) was installed for soil remediation, and an innovative air sparging system was installed for cost effective groundwater cleanup. A bioventing system was also applied in selected areas. The vapor extraction wellfield consists of 26 extraction and monitoring well points, with multiple screened casings. The air sparging wellfield consists of 32 sparging wells with a designed maximum flow of 400 scfm. The systems began operation in 1993, and have resulted in the estimated removal of approximately 30,000 pounds of contaminants, or about 90% of the estimated mass in place. The combined vapor extraction/air sparging system is expected to reduce the time for on-site groundwater remediation from 1/3 to 1/6 the time when compared to the conventional pump and treat method for groundwater remediation