Professional Engineers Of North Carolina

SUM 2014

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8 the Professional Engineer Summer 2014 Standards have been developed for projects requiring CFA in fll applications, with one aptly titled: ASTM E2277 Standard Guide for Design and Construction of Coal Ash Structural Fills. Tis comprehensive document recommends careful review of the specifc CFA proposed for use, the design and hydrogeologic setting prior to use. In particular, CFA used in conformance with the guide will frst be subjected to robust environmen- tal (e.g., leachability) and geotechnical (e.g., strength, slope stability) testing and analysis. It also will be placed outside a 100-year food plain and above the seasonal high groundwater level. All of these and more details are to be reviewed by a registered professional. Te guide notes that a "professional" may include a professional engineer or professional geologist, although it is not limited to those categories. Likewise, North Carolina has specifc regulatory requirements for structural flls. Tese regulations — "Requirements for Benefcial Use of Coal Combustion By-Products" — codifed in 1994 (15A NCAC 13B .1700) require those proposing to use CFA as a fll to notify the Division of Waste Management of the N.C. Department of the Environment and Natural Resources at least 30 days prior to placement. When the volume exceeds 10,000 cubic yards, these regulations require construc- tion plans and a stability analysis (when neces- sary), all of which is to be "signed and sealed by a registered professional engineer in accordance with sound engineering practices." Leachability testing also is required, according to the Toxicity Characteristic and Leaching Procedure (TCLP) test, a method developed by the EPA to defne the limit of whether a material is hazardous or not. Tis limit is operationally defned by the values specifed in Table 2, as compared with typical CFA leaching values. Te CFA values are provided only as an example. Site specifc data are always required. Tere has been some concern expressed regarding the use of CFA at the Charlotte airport, at least as an embankment for runway and taxiways. Te general disposition is that while it may be appropriate to use CFA at a small regional airport such as Asheville, the potential risk is too great to tolerate its use under a runway at the world's sixth busiest airport in terms of aircraft movement. Indeed, one could imagine the impact and delays associated with having to dig up an in-service runway there. So with that in mind, let's review specifc concerns — including leachability, stability and strength, Biggest U.S. coal-ash spills Location Year Plant Amount in gallons Kingston, Tenn. 2008 Kingston Fossil Plant 1.1 billion Bangor, Pa. 2005 Martins Creek Station 100 million Eden 2014 Dan River Station 27 million F E AT U R E S T O R Y

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