Commercial Dredging to End on Allegheny River
16 June 2013
By Don Hopey
The freshwater clams will be happy.
By the end of this year the last commercial dredging company
operating on the Allegheny River will scoop its last
industrial-sized bucket of Ice Age-old aggregate from that flow,
ending a century-old practice that in recent years has raised
myriad environmental concerns.
Hanson Aggregates, a subsidiary of Heidelberg Cement, the world's
largest aggregates producer, confirmed last week that it plans to
pull its only barge-mounted crane shovel from the Allegheny, where
it's scraping the publicly owned river bottom in Pool 5, about 31
miles from Pittsburgh's Point.
The decision will end the "mining" of sand and gravel from the
Allegheny River for commercial sale and use in road and building
construction, although Hanson and another commercial dredger,
Tri-State River Products Inc. of Beaver, will continue dredge
barge operations in the Ohio River. Hanson will also continue to
operate its land-based quarries for crushed rock.
"We're going to be winding down our Allegheny River operations and
the equipment will either be redeployed or sold," said Jeff Sieg,
a Hanson spokesman based in Houston, Texas. "Our permits are
expiring in the Allegheny at the end of the year, and at this
point we don't see any more economically viable areas to do that
work in that river."
Part of Hanson's economic calculations involve the cost of
complying with environmental rules that restrict commercial
dredging to limited areas of the river to protect rare freshwater
mussels, clams, darters and shallow, native fish habitat.
"There are certain areas of the river that we can't mine and other
areas that if we do want to mine we must do so in an
environmentally responsible way," Mr. Sieg said. "That's part of
the economics. The environment is certainly a piece of that."
Hanson holds the lone permit on the Allegheny, issued by the state
Department of Environmental Protection, which allows it to operate
only in Pool 5, from river mile 30.7 to 31.7.
Myron Arnowitt, state director for Clean Water Action, an
environmental group that has opposed dredging for two decades,
welcomed the decision to end commercial dredging on the Allegheny
"We're glad to see there will not be further mining of aggregate
from the river and hope the damage done to the river can be fixed
and the river restored in the future," Mr. Arnowitt said.
Retreating glaciers dropped large deposits of rock, gravel and
sand in Western Pennsylvania after the last Ice Age, and
commercial dredgers began scooping up those moraine deposits more
than a century ago, first the sand for glass making and, since the
1950s, the rock, gravel and sand for road and building
construction. The harder glacial rock is valued by state road
builders for its durability and skid resistance properties.
But by the 1990s, federal and state studies began to show
increased environmental impacts from river dredging, including
erosion of riverbanks and islands, increased siltation and
sedimentation, damage to fragile freshwater mussel and clam beds,
degradation and destruction of shallow water fish habitats and
depletion of dissolved oxygen in dredge holes up to 60 feet deep.
Commercial dredging is different than the shallower navigational
dredging done to keep the river channels deep enough for
industrial barge transportation.
The aggregates industry, which once pulled 4 million tons of sand
and gravel from the rivers a year, has questioned the study
findings, denied it caused those problems in the rivers and fought
state and federal regulation.
But the amount of the publicly owned river bottoms available for
dredging has continued to shrink. By 2006, the number of
commercial dredgers had fallen to three and environmental concerns
had restricted the scooping sand and gravel to a 100-mile stretch
of rivers, that included Pools 4, 5, 7 and 8 on the Allegheny,
from Harrison in Allegheny County to Washington Township in
Armstrong County, and on the Ohio River in the Montgomery and New
Cumberland pools, between Baden and Midland in Beaver County.
State dredging permits issued in 2006 required companies for the
first time to conduct mussel and fish surveys, study water quality
and fund habitat restoration programs. In 2009 the state Fish and
Boat Commission decided not to follow the recommendations of its
biologists and list two river mussel species, the salamander and
rayed bean, as endangered and threatened, but the dredgers were
required to accommodate them when they were found in permitted
"I think some of the environmental restrictions probably helped
companies think about phasing out their operations," Mr. Arnowitt
said. "The limitations helped protect some areas of the river, and
now ending dredging is going to be the best thing for the river."
The retreat of commercial dredging is reflected in the sand and
gravel production numbers reported by the DEP, which show sand and
gravel pulled from the rivers totaled 2.8 million tons in 2006 and
fell steadily in subsequent years. In 2011, the last year for
which production totals were provided by the DEP, river aggregate
tonnage totaled 1.2 million tons.
Don Hopey: email@example.com or 412-263-1983.