UTILIZATION OF FLY ASH AND COAL MINE REFUSE
AS A ROAD BASE MATERIAL
Robert B. Scott, Chief
Roger C. Wilmoth, Project Engineer
Daniel L. Light, Physical Science Technician
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
INTRODUCTION
Two coal-related waste products—fly ash and coal mine refuse—were investigated for
possible use as road base materials at the U.S. Environmental Protection Agency's (EPA)
Crown Mine Drainage Control Field Site near Morgantown, West Virginia.
Fly ash is a waste product from coal-powered, steam-generating stations that supply
a major portion of the nation's electric energy requirements.    Total ash collection (fly
ash, bottom ash, and boiler slag) soared to a record 54 million tonnes/yr (59.9 million
tons/yr) in  1975 resulting from the burning of approximately 360 million tonnes (400
million tons) of coal (Figure 1).    This material is readily available, particularly in the
Appalachian Region.    In the Monongahela River Basin alone, some 1.0 million tonnes
(1.1  million tons) of fly ash and 319,000 tonnes (350,000 tons) of bottom ash were
collected during 1975.    Nevertheless, only 14.6% of the available ash is currently being
utilized—some in the construction industry as concrete, fill material, asphalt mix, etc.,
and some in soil amendment of orphaned strip mines and coal mine refuse piles.
Coal refuse, gob, and other reject materials are produced from the coal mining process in great quantities.    An annual average of 91  million tonnes (100 million tons) was
produced during the period 1968-73. In addition, stringent environmental standards require that a large percentage of coal be cleaned to make it environmentally acceptable
for consumption, thus yielding more refuse. The   mining, crushing, and washing processes tend to concentrate many impurities in the refuse and gob. Most coal-cleaning
methods employ gravity separation to remove impurities; thus, the more dense materials
such as clays, shales, and pyrite lenses are removed to the refuse dump. This waste
material may be extremely toxic and usually requires special handling and disposal to
prevent air and water pollution problems.
This study was to utilize fly ash and coal mine refuse in the construction of a parking lot to determine their usefulness as road base materials. An evaluation was made to
determine if water percolating through the base material would leach undesirable material and become a pollution problem.
In cooperation with EPA, Dr. David Anderson of West Virginia University  designed
the base-course mixtures; the Fort Martin  Power Station   (Monongahela Power Company) supplied fly ash from their coal-fired power plant; and the Humphrey Cleaning
Plant (Christopher Coal Company) supplied coal mine refuse.
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