Over the years, EPA has become aware of the environmental footprint associated with cleanup activities at Superfund sites. Equipment used during remedy construction can include generators, backhoes, excavators, and dump trucks. These mobile and stationary sources can use substantial amounts of energy (e.g., electricity, gasoline, diesel, other fuels) and emit harmful compounds, including nitrogen oxides (N[O.sub.x]) sulfur dioxide (S[O.sub.2]), carbon monoxide (CO), and particulate matter (PM).
One technology used to retrofit diesel engines, selective catalytic reduction (SCR), shows particular promise for reducing N[O.sub.x] emissions. N[O.sub.x] emissions are important on the local scale, as studies have shown that they play a major role in the production of tropospheric or ground-level ozone. In December 2012, EPA issued a report entitled "Analysis of the Benefits of Green Remediation Best Management Practices for Local Air Quality." The report discusses the preliminary findings of the agency's study of changes in local air quality following the application of SCR technology using a gas-phase air quality model.
Green Remediation BMPs for Local Air Quality
Under the Clean Air Act, EPA has identified nitrogen dioxide (N[O.sub.2]), ozone, lead, CO, sulfur oxides (measured as S[O.sub.2]), and PM as the nation's criteria air pollutants. Ground-level ozone, which can be inhaled and lead to respiratory problems and other adverse health effects, is produced when photochemical reactions occur between N[O.sub.x] and volatile organic compounds (VOCs). State and federal standards for ozone indicate that exposure to concentrations as low as 0.09-0.12 parts per million (ppm) for one hour can adversely affect lung function. For ozone exposure exceeding eight hours, average concentrations as low as 0.08 ppm can have an adverse effect. Efforts to reduce emissions of these compounds and other air pollutants are a key component of green remediation strategies.
In its report entitled "Cleaner Diesels: Low-Cost Ways to Reduce Emissions from Construction Equipment," (EPA-100-R-07-2, March 2007, available at http://www.epa.gov/sectors/pdf/ emission_0307.pdf), EPA states that "the construction sector is a significant contributor to emissions, creating 32% of all mobile source NO emissions." In a fact sheet entitled "Green Remediation Best Management Practices: Clean Fuel & Emission Technologies for Site Cleanup" (EPA-542-F-10-008, August 2010, available at http://www.epa.gov/tio/download/ remed/clean-fuel-emis-gr-fact-sheet.pdf), the agency discusses several ways, including advanced diesel technologies, to reduce emissions of air pollutants from internal combustion engines.
The majority of these technologies involve retrofitting vehicle and equipment engines with an advanced exhaust after-treatment system to reduce diesel emissions. Relevant green remediation best management practices (BMPs) focus on the use of the following diesel retrofit technologies: 1) diesel oxidation catalyst, 2) diesel particulate matter filter, 3) partial diesel particulate filter, and 4) SCR. The first three technologies can reduce emissions of PM, hydrocarbons, and CO. SCR is the only advanced retrofitting technology that can be...