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leaching of contaminants, particularly heavy metals. Whether or not the leachate 
will contaminate groundwater will depend on the absorptive capacity of the natural 
soil, which is normally quite high. A far more serious and more probable impact can 
occur when saline sediments are placed in a freshwater upland environment. Salt 
will leach from most dredged material and whether or not it will comtaminate 
groundwater must be carefully evaluated on a case-by-case basis. 
In terms of time, effort, and cost, the most expensive aspect of confined dredged 
material disposal can be the land acquisition. The DMRP included studies aimed at 
alleviating or lessening this problem. These dealt with methods to increase the stor- 
age capacity of existing sites and-or concepts for making existing sites reusable. 
Field tests proved that it is possible to dewater even some of the more difficult 
types of dredged material so that disposal sites can store more sediment and less 
water. A side benefit of this dewatering is improved engineering characteristics of 
the densified material. Through field investigations and tests, surface trenching 
with an available surplus Marine Corps vehicle called the Riverine Utility Craft 
proved to be cheap and effective in providing natural drainage. Whereas more com- 
plex and even exotic dewatering methods such as underdrainage systems and elec- 
tro-osmotic dewatering may be feasible where the cost can be justified, here is a case 
where the cheaper technique, relying heavily on nature, was shown to be generally 
the most effective. 
Dredged material, paricularly dewatered dredged material, has value for landfill- 
ing or in construction. Every cubic yard that can be removed from a containment 
area and used, donated, or sold offsite for any purpose is a cubic yard of new storage 
capacity gained. In conjunction with the Corps Districts, concepts were developed 
for disposal area reuse for both existing and planned disposal sites. Numerous possi- 
bilities exist for separating and handling materials in a site, and actual field situa- 
tions have demonstrated that uses within the site for purposes such as haul road 
construction and dike raising are too often overlooked as completely viable concepts. 
Dredged material is also a substance that can be used to create or improve wild- 
life habitats—examples of this already exist in nearly all parts of the country. How- 
ever, it is known that the past occurrences were primarily accidental rather than 
planned. Realizing that even the most productive habitats sometimes can be out of 
place within an ecosystem, the DMRP concentrated on understanding the natural 
processes and developing guidelines on exactly what should be done, where and 
when, and what are the relevant considerations in all phases from site selection to 
follow-up management. 
Certain basic studies were concerned with wetland plant productivity from two 
points of view. Knowing the relative productivity of a species is one factor in select- 
ing those suitable for planting at a habitat development project. It is also one factor 
in the extremely difficult problem of determining the value of a wetland being eval- 
uated as a disposal site. Studies showed, for example, that the ability of at least one 
species to recover from burial beneath dredged material up to 9 inches thick is 
greater than expected. This information will be helpful in selecting areas and meth- 
ods of disposal should a wetland area have to be used for disposal. 
Considerable attention was given to the uptake of chemical contaminants by 
marsh plants as an obvious concern in decisions on developing marsh habitat using 
dredged material. Uptake was found to occur in different ways and at different 
rates in most plant species, but the amounts of contaminants involved were not so 
large as to cause major concern. The question of how much uptake is too much was 
not resolved and is not likely to be anytime soon; however, evaluations of uptake 
should be made with an awareness of the natural functioning of a wetland system 
as a contaminant processor. The end product sought by the research was a test that 
can be used to predict the pattern of uptake from a particular type of material. To 
this end, it was largely, but not entirely, successful since certain contaminants have 
proven difficult to predict as far as behavior is concerned. 
Marsh creation using dredged material is now a proven, viable alternative that 
can be designed and implemented as reliably as any other alternative. Also, certain 
misconceptions about this alternative were firmly dispelled. In particular, it can be 
easily demonstrated that marsh development does not necessarily eventually pre- 
clude the disposal of material from subsequent maintenance dredging projects. 
There are examples where phased marsh development, with or without other dispos- 
al alternatives, has been planned in such a way as to accommodate maintenance 
dredging for periods of 50 years or more. 
While marsh development is a field-tested and proven alternative, it is not a 
simple one and it is often not cheap. However, costwise, it is definitely competitive 
with other alternatives and cheaper than some. Marsh development is not unusual- 
ly difficult from an engineering point of view, but it is difficult operationally in rela- 
