Multi-Phase Remedial Strategy at Coal-Fired Power Plant

Power plant box

Client Challenge

A national power company is progressing in its long-term strategy for the decommissioning, remediation, and restoration of a former coal-fired power plant that served thousands of customers in the Washington, DC metro area. Petroleum impacts were noted to soil and groundwater following the closure of two 25,000-gallon underground heating-oil storage tanks centrally located within the power plant complex. GES was asked to implement a low-impact yet highly aggressive approach to site remediation and protection of an adjacent National Park Service (NPS) property, popular biking and hiking trails, and the Potomac River. Concerned and vocal stakeholders included regulators from multiple state and municipal jurisdictions as well as the NPS and community groups. 

GES Solution

An innovative approach was required to effectively meet remediation goals while employing the highest level of sensitivity to public awareness and protection. To develop a fit-for-purpose solution, GES evaluated all site characterization data, developed a conceptual site model, and conducted extensive evaluation of alternative remedial approaches. GES’ mobile data acquisition and processing laboratory (DAPL) was mobilized to conduct real-time evaluations of multiple remediation technologies under varying conditions, both on- and off-site. 

The remedial solution is a comprehensive, phased approach that addresses light non-aqueous phase liquids (LNAPL) impacts across the impacted properties. Technologies include pump-and-treat, total phase extraction (TPE), and biosparge, followed by monitored natural attenuation (MNA). Extracted fluids undergo preliminary treatment through an oil-water separator and a series of filtrations before being discharged to the sanitary sewer system. A low-pressure sensing system detects leaks, creates alarms, and can shut down the system in the instance of any leakage. This feature, combined with remote monitoring controls and telemetry, allows continuous system operation with additional environmental protections.

Client Value

GES supported the power company with technically sound public advocacy, helping it to develop and implement - under extensive scrutiny - an innovative and practical remedial solution. The high-efficiency and low-profile approach was devised to achieve lower energy consumption and greenhouse gas emissions while also reducing the need for manual operation and monitoring.