SITE MANAGEMENT CHALLENGES (cont.)

Technical Note DOER-N2

April 1998

placement site, tests for sediment chemistry and tissue chemistry are becoming more routine. Use

of sediment profile imagery (SPI) is becoming more routine to detect layers of dredged material at

thicknesses below those resolvable from bathymetric surveys.

Dredged material placement is now receiving much greater interest. Confirming that the contractor

is meeting contract specifications for placing material in precise locations inside the disposal site

(not outside the site, which could potentially damage nearby resources) is considerably more

important and more practical. A related issue is the increased time and cost required to designate

new sites. This makes controlling placement within the disposal site to maximize site capacity while

minimizing environmental impacts even more significant.

The ability to manage all these diverse data and use them effectively meshes well with the strengths

of a GIS-based system. A GIS is an excellent tool to archive, display, and analyze spatial data.

Many of the difficulties of site management result from the inability to easily access the data and

display it on a common datum. Using the spatial nature of the data, the GIS's database can contain

the many different types of data in layers that can be easily retrieved and displayed.

In addition to dredging project management, resource agencies and environmental groups have

become more involved in the dredging process, resulting in substantial increases in the number of

requests for information. Also, the number of lawsuits associated with dredging projects has

increased, adding to the number of requests Districts receive for information. Providing timely

answers with a minimum of effort can be difficult. The relational database included as part of the

GIS allows a range of queries to be made with minimal effort.

Concerns over the fate of dredged material during dredging and during and after placement in the

disposal site are increasing. The ability to predict water column impacts during dredging and

placement, the area of the bottom covered by a placement operation, the height of the mound created

during a placement operation, and the long-term stability of a dredged material mound can all be

crucial to obtaining resource agency permission to execute a given dredging project. Reliable

prediction of long-term mound stability is critical to both maximizing site capacity and to creating

effective site management plans.

Over the years, WES has developed or refined a number of numerical models that predict various

aspects of dredged material fate that can be used to address concerns such as those just discussed.

However, the ability of District staff to use these models has often been limited by less than

user-friendly interfaces combined with difficulties in accessing the data needed to drive the models.

A number of the WES dredged material fate models are to be included in DMSMART. Prior

limitations on difficulty of use and access of input data will be overcome.

The above discussions show that a GIS software package with access to WES dredged material fate

models could facilitate dredging project management. The following section describes the specific

site management challenges faced by the New York District that prompted the development of a

District-specific open-water site management software system.