This April, site owners, regulators, consultants and contractors came together at the Fifth International Symposium & Exhibition on the Redevelopment of Manufactured Gas Plant Sites (MGP 2014) to discuss the challenges of manufactured gas plant (MGP) site remediation and new approaches for site redevelopment.
For more than 150 years, beginning in the early 1800s, MGPs turned coal into gas that fueled homes and industry across the U.S. Although manufactured gas was phased out (replaced by cheaper natural gas) and the thousands of plants across the country were closed by the mid-1900s, we are still grappling with their environmental legacy.
Cleanup of former MGP sites is complicated not only because of the complex contaminants left behind but also because of unique site characteristics including sites that have been built over and reused before underlying environmental issues were identified.
As part of the conference, I presented “Design of a Remedy to Control NAPL Transport and Allow for Flexible Redevelopment”which highlighted TRC’s patented sediment capping technologies that address NAPL-containing sediment and bank soils at MGP sites. I highlighted DTE’s former Broadway Street MGP site in Ann Arbor, Michigan and the combined excavation and cap approach used to control NAPL, reduce the upland soil excavation approach and achieve remediation levels allowing for site redevelopment.
My colleagues, Katherine Vater, P.E. and Gary Hunt also presented at the MGP 2014 conference.
Katherine’s poster presentation,“Management of NAPL Contaminated Sediments with Engineered Caps – How Cap Layers May or May Not Prevent NAPL Releases,”described the function and effectiveness of layered sediment caps. She described that the use of commonly available construction materials on slopes can control NAPL transport, reduce costs of materials and placement during construction, and maintain the connection between the groundwater and surface water systems.
Gary’s presentation: “Perimeter Air Monitoring for VOCs and PM at MGP Sites- Exceedances – Frequency, Origins/Causes and Mitigation,”described issues related to effective air monitoring during remediation at MGP and other industrial sites. Frequently the location of the remediation area causes exceedances, and extra planning for odor control near site boundaries can minimize exceedances and schedule delays.
A fourth abstract,“Installation of an Impervious Cap for Control of Residual NAPL Migration, Construction Issues and Solutions,” was co-authored by Katherine and myself, and was presented by John Collins of AquaBlok LLC and Gary Loveland of Terra Environmental. This presentation described in detail the materials and construction techniques used at DTE’s former Broadway Street MGP site including managing work on a complex site in the center of an urban area.
If you have compliance, characterization, or cleanup concerns related to former MGP sites, please share your questions and comments below.