Working PaperPDF Available
Potential for diverting Mississippi River industrial
discharges to bordering watershed
Michael G. Waldon and Louis Landesman
Abstract
Louisiana is experiencing rapid coastal land loss and deterioration. Numerous
approaches for protecting and restoring our coast are being investigated and
pursued. Among these approaches is freshwater diversion from the Mississippi
River into the adjacent watersheds. At this time the local, state, and federal
governments are operating freshwater diversions at several locations including
Bayou Lafourche, Violet, and Caernarvon. One obstacle to further development
of diversions is the high capital and operating costs associated with planning,
construction, and operation of such diversions. Diversion of industrial once-
through cooling water could provide a cost-effective means of providing
freshwater to reduce the loss of coastal wetlands and increase wildlife resources in
coastal Louisiana.
Introduction
Louisiana is experiencing rapid coastal land loss and deterioration. In a recent
issue of the Journal of Coastal Research (Boesch et al. 1994) the authors
concluded the following:
"Net loss of coastal wetlands in Louisiana would probably be occurring
without human intervention in this ecosystem because of the limited
wetland-building potential of the delta presently occupied by the
Mississippi River. However, a variety of human activities have caused
wetland loss to accelerate greatly. These activities include construction of
canals for transportation and oil and gas development and the hydrological
modifications that result from them; impoundments and failed land
reclamation; and interference with flood water flow across the natural
levees of the river. Without mitigation or restoration, the modifications
resulting from these activities will continue to cause high rates of wetland
loss."
One possible approach to mitigating loss of coastal land is freshwater diversion
from the Mississippi River into the adjacent coastal watersheds. At this time the
local, state, and federal governments are operating freshwater diversions at
locations including Bayou Lafourche, Violet and Caernarvon. One obstacle to
further development of these diversions is the high capital and operating costs
such diversion structures require. A proposed expansion of the Bayou Lafourche
diversion to 2000 cfs, for example, is expected to cost 24 million dollars for
planning and construction. Diversion of industrial once-through cooling water
could provide a cost-effective augmentation to these costly projects.
Once-through cooling water is utilized by many of the more than 70 industries
(power generation, chemical manufacturing and petroleum refining) located along
the Mississippi River downstream from Baton Rouge. These sectors withdraw and
return approximately 6 billion gallons of water per day (9000 cubic feet per
second) from the Mississippi River mainstream, or roughly 2 percent of the annual
average streamflow (Lovelace, 1991a, 1991b, 1996).
Funded by federal and state appropriations, a significant effort is currently
underway in Louisiana to protect and restore our coastal lands. One element in
this effort is the establishment of freshwater diversions. The Bayou Lafourche
and Teche-Vermilion River diversions have illustrated the potential these projects
can have to improve water quality and water supply (Waldon and Richards, 1992).
The Caernarvon diversion has provided substantial, though anecdotal, evidence of
improvements in fishery production (Waldon and Bryan 1995). Cost-benefit
studies of the Caernarvon and Davis Pond freshwater diversions are available, and
can provide a preliminary basis for valuing the potential wetland enhancement and
protection contributed by other proposed diversion projects. Caernarvon and
Davis Pond have typical diversion flows of 7000 and 4000 CFS, respectively, and
annual benefits of 9.2 and 7.4 million dollars. This implies an annual benefit of
$1,300 and $1,800 per CFS. Thus, a 1000 CFS diversion of once-through cooling
water would likely have a value in excess of one million dollars per year
(reference).
The redirection of once-through cooling water discharges provides a substantial
and immediate potential for diverting Mississippi River water at little or no cost in
tax dollars. Additionally, providing multiple freshwater diversions along widely
spaced locations is a more environmentally sound configuration than would be
economically achievable using specially constructed pump or siphon projects.
It is anticipated that River industries will adopt the diversion as an improved
method of handling once-through cooling water discharges. Although direct
economic incentives to these industries will vary, we feel that Louisiana industries
are environmentally sensitive and are eager to cooperate in developing
environmental enhancements. The possibility of obtaining wetland mitigation
credit through participation in this program may provide a strong additional
incentive for industrial participation.
Methods
The Mississippi River has sediment loads potentially available to offset coastal
subsidence. All of the Louisiana coastal restoration plans include a call for
diversion of significant amounts of Mississippi River discharge away from the
present deep channel. We will examine several industries presently using
Mississippi River water for cooling purposes. These industries presently send their
cooling water with its suspended sediment back into the river. By selecting a few
of the larger diverters as potential candidates for the re-diversion of their cooling
water resources, we will determine how much of this water is available, how much
sediment it will likely contribute to the receiving wetland, and what will be the
total impact on the wetlands that receive this redirected cooling water.
Methods - Typically, River industries are located on the natural river levee (the
high land adjacent to the channel), and behind the protection of the manmade
levee (see figure 1). Water intake pumps lift water over the manmade levee, and
return water pumps lift wastewater over the levee for discharge. For most of the
230 miles of River below Baton Rouge, swamp or marsh wetlands parallel both
banks of the channel. These wetlands have been hydrologically isolated from the
River by construction of the levee system and closure of natural distributaries such
as Bayou Lafourche.
Data on the geographic location of Mississippi River industries has been compiled
in a GIS database by the investigators (Bostock, et al., 1991; Richards, 1992, 1993)
under a contract with the Louisiana Department of Environmental Quality
(LDEQ). A map showing the location of the 10 large industries that may be
candidates for using their cooling water for diverting to neighboring watersheds is
given in figure 2. Table 1 gives a list of these candidate industries, their location
by river mile and parish and the amount of water they presently divert and could
potentially provide. Information on design discharge flow rates and chemical
analyses of discharges are available in public records at the LDEQ headquarters,
but have not been entered into a comprehensive computer database. Data on
internal and final outfalls for each industry will be extracted from the LDEQ files.
These data will be incorporated into the existing Mississippi River GIS which was
developed by the investigators.
The LDEQ has also defined for all waters of the state. These standards include
both narrative criteria and numerical criteria.
The numerical criteria are defined for substances and properties such as
temperature, dissolved solids, hardness, and synthetic organic compounds.
Because of the high critical discharge of the Mississippi River, most bulk
chemical plant NPDES permit limitations for River outfalls are determined by
technology based industry OCPSF guidelines (the Organic Chemical, Plastics and
Synthetic Fibers Effluent Guideline requirements). EPA and LDEQ use a
screening dilution model which calculates water quality based permit loading
(mass per day) limits from receiving stream standards, receiving stream critical
dilution discharge, and outfall design flow. Diverting industrial discharge into
adjoining watersheds may potentially result in more stringent limits for both the
diverted discharge as well as the un-diverted fraction of the discharge. Following
preliminary identification of sites, a water quality screening will be applied to
determine the anticipated impact of diversion on permit limitations.
The EPA has also recently initiated a "Project XL" which may grant exemption
from specific regulatory requirements of the current system at specific facilities
and commits project participants to achieve a higher level of beneficial
environmental results through alternative approaches. The proposed project will
investigate the possibility of application to Project XL at the selected sites.
Database resources are available through state agencies to locate the candidate
industries and their cooling water discharges. Additionally, GIS and other
databases are available at Louisiana academic institutions. In addition a GIS data
system exists at the National Wetland Research Center that describes and predicts
the impact freshwater diversions will have on wetlands receiving this once-
through cooling water (Wei and Mitchell 1995).
Discussion
Along Louisiana’s Mississippi River industrial corridor, Waste heat from
industrial processes is often transferred to a pumped intake of river water and
discharged using a once-through cooling water process. The once-through water
may impact receiving water through temperature increase and chemical additives,
principally chlorine. Although these impacts could possibly affect a local area
near the cooling water discharge outfall, diversion of discharge away from the
River would likely have significant and broad-scale beneficial impacts. Benefits
could include reduction in salinity, and addition of nutrients and sediments. Thus,
redirection of once-through cooling water to create new river diversions could
help reduce coastal land loss and improve ecological function in basins bordering
the Mississippi River.
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ResearchGate has not been able to resolve any citations for this publication.
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