ENVIRONMENTAL EFFECTS OF BGE'S BRANDON WOODS CCP STRUCTURAL FILL SITE

摘要

The Maryland Department of NaturalResources Power Plant Research Program (PPRP) hasevaluated the potential environmental effects ofusing coal combustion products (CCPs) as structuralfill at Baltimore Gas and Electric Company's (BGE)Brandon Woods Energy Business Park. The 466-acre sitecontains topographic low areas, and CCPs have beenplaced at the site since 1982 to raise the site touniform grade and facilitate construction of lightindustrial and warehouse buildings. PPRP studied thesite to determine if the structural fill applicationat Brandon Woods was protective of ground and surfacewater quality. The evaluation was part of PPRP'songoing evaluation of both operating and retired CCPfill sites in Maryland. The study was intended toincrease the understanding of regulators, CCP users,and the public regarding CCP impacts on water quality,and to ensure that this type of beneficial use is aviable application for other sites in the state.Ground water quality conditions were evaluated usingdata collected from the time the facility began CCPfilling operations in 1982, through March 1998. Groundwater quality at the site is monitored in the shallowaquifer, which is generally present 2 to 10 feet belowthe bottom of the CCP fill, and a deep semi-confinedunit 30 to 70 feet below the bottom of the fill. Sulfate,iron and manganese derived from the fill have beendetected in downgradient monitoring wells completedin the shallow aquifer. The extent of sulfate, ironand manganese derived from the fill in the shallowground water is localized and these constituents arenot adversely affecting surface water quality.Furthermore, no sulfate, iron, manganese, or traceelements, such as arsenic and selenium, have beendetected in the deep ground water.The localized extent of groundwater quality impactsbeneath the CCP structural fill and the absence oftrace elements indicate that several sitecharacteristics minimize potential adverseenvironmental impacts from leachate generation. Thesecharacteristics include: 1) a shallow fill thicknessof 16 feet on average which results in dilute leachate;2) attenuation of the dilute leachate in theunsaturated zone; and 3) the presence of buildings andpavement over much of the site which limits the volumeof infiltration through the fill. Furthermore, thestudy illustrates that although structural fills maycause elevated concentrations of iron, manganese andsulfate in ground water, localized impacts by theselow toxicity constituents may be acceptable whenbalanced against the environmental and economic benefits of CCPs use.