12    TRANSPORT MODELING OF CONTAMINATED
INDUSTRIAL ABRASIVES FROM A SMALL
URBANIZED WATERSHED
Paul D. Kuhlmeier, Senior Staff Consulting
Timothy J. Champagne, Civil Engineer
International Technology Corporation
Knoxville, Tennessee 37923
INTRODUCTION
An unprecedented public awareness of pollution problems in the United States is evident and
growing. Until the advent of the U.S. Environmental Protection Agency (EPA) in 1970, only one
major law addressing contamination had been passed, the Solid Waste Act in 1965. In 1986, then-
EPA-Administrator Lee Thomas commissioned a study by senior staff members to address the
question of where America's most pressing pollution concerns stand. One recurring problem that
ranked near the top of the study's list was nonpoint source pollution. A separate EPA study1 estimates
that 65 percent of stream pollution is produced from nonpoint sources. A large body of information
has been gathered pertaining to farmland, feedlot, and industrial runoff pollution. However, one
component of nonpoint source pollution has only recently been identified for study; that is pollution
caused by abrasives blasting of materials such as bridges, ships, and buildings. This study addresses
this issue as it relates to sandblasting ship components and the operation impact on the environment.
At NSY Mare island (Site 900), sandblasting practices are carried out in open areas. The 900 Area is
in a relatively small watershed measuring approximately 990 feet long and 500 feet wide at its widest
point. It is completely paved with asphalt. The integrity of the asphalt is poor in several places.
Sandblasting of large and small ship parts is practiced throughout the entire watershed. An abrasive,
consisting of a nickel-copper slag, called greensand is used to strip paint from metal surfaces. Uncontrolled runoff from the site deposits onto an estuary which comprises the rim of the Mare Island
peninsula. Mare Island Strait borders the strip estuary (it occupies less than 2,000 linear feet of
coastline).
A wide range of design storm frequencies (1-year to 100-year) were selected for the purpose of
estimating the amount of flow which could be expected from the site. Synthetic hydrographs for the
drainage basin were developed using the U.S. Army Corps of Engineers HEC-1 model2, one of the
most widely employed hydrologic simulation codes. Sediment transport was simulated through the
use of the U.S. Army Corps of Engineers HEC-6 model.3 The model, which is well suited for classical
river sediment transport, is postulated here to hold promise for estimating sheet flow sediment
transport. The HEC-6 model was also selected because of its broad acceptability.
RUNOFF MODELING
To determine the potential runoff under different conditions, average meteorological conditions
were compiled using storm frequency information from 1947 through 1987 and isohyetal precipitation
charts. The storm distribution type for the study area has also been defined by the SCS as type IA.
Three primary subbasin areas were defined that required independent modeling:
• Subbasin 1 (shown in Figure 1) defines the asphalt area which is further subdivided into
four blocks for runoff analysis. The Kinematic Wave Model was used for flow
modeling.
• Upgradient Subbasin 2 defines the watershed behind the 900 Area site. This is an area of
steep grass-covered slopes.
• Crossgradient and upgradient, Subbasin 3 is located south of the containment area.
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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