Fly Ash Fills a Valley

by Robert Turgeon, (M.ASCE), Soils Engineer, PennDOT.; Harrisburg, Pa.,

Serial Information: Civil Engineering—ASCE, 1988, Vol. 58, Issue 12, Pg. 67-68

Document Type: Feature article


The Pennsylvania Department of Transportation (PennDOT) recently placed narly 400,000 tons of fly ash in a structural fill along I-279 near Pittsburgh. The fly ash, believed to be the largest tonnage in any Interstate project, came from nearby coal-fired powerplants. Spread by dozers much like soil, the fly ash is encased in a geotextile-aggregate drainage blanket spanning the entire width of the valley for the 1,200 ft length of the fill. The drain consists of 9,500 cu yd of gravel sandwiched between 104,500 sq yd of needle punched nonwoven fabric. Water collected within the fly ash portion is discharged through the blanket drain via a system of pipes to an existing drain. The fill, about 40 ft high, is buttressed on all sides by natural slopes and previously constructed embankments. It is topped by at least 5 ft of soil and carries an expressway through the valley.

Subject Headings: Drainage | Fly ash | Fills | Water discharge | Drainage systems | Project management | Mine wastes | Coal | Pittsburgh | Pennsylvania | United States

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