Disposal Sites
When the Corps of Engineers (Corps) initiated the feasibility study for the Columbia River Channel Improvement Project (CRCIP) an Ocean Dredged Material Disposal Site Technical Working Group (Taskforce) was formed. The purpose of this Taskforce was to assist in identifying the best long-term offshore disposal options for the Mouth of the Columbia River Project (MCR), maintenance of the 40-foot navigation channel, as well as the CRCIP. The goal of the Taskforce was to ultimately develop new candidate ocean disposal sites for the federal navigation projects. The Corps and Environmental Protection Agency (EPA), Region 10, hosted facilitated workshops from July 1997 through May 1999 with numerous resource agencies and stakeholder groups, including: NOAA Fisheries, US Fish and Wildlife Service, Oregon Department of Fish and Wildlife, Washington Department of Ecology, the sponsoring ports, and the Columbia River Crab Fisherman's Association (CRCFA). The Corps and EPA invested $10 million in data collection, evaluation, and facilitated workshops to arrive at locations for disposal that were feasible from a disposal standpoint and represents least conflict to the 17 resources of concern identified and developed by the Taskforce.
The Draft Integrated Feasibility Report and Environmental Impact Statement (1998) presented the following proposed sites for review and comment by the public, resource agencies and members of the Taskforce. These sites include Expanded Site E
(Shallow Water Site), the North Site and the South Site. The south boundary of the North Site eliminated the area within and immediately offshore of the entrance to the Columbia River due to navigational safety considerations. The portion comprising Peacock Spit also was eliminated because of potential navigational hazards to small vessels. Further, disposal on Peacock Spit would impact crab fishing activities as this area was identified by the crab fishermen as a location contributing to a high percent of their crabbing income. The North Site reduced negative impacts while preserving the positive benefits. Benefits of the North Site were considered to be beach nourishment and the protection of cultural resources (shipwrecks).
In addition, the North Site was located in the nearshore transport zone and an area of high wave energy. Sediments in this area are similar to the dredged material. The material place in this location would disperse and contribute to nourishing the beach if placed in less than 60 feet of water. The benthic organisms in this area area adapted to this mobile sand environment and therefore would be less impacted by direct dredged material placement and subsequent sediment redistribution.
The proposed South Site in the DEIS included both a nearshore and offshore component. Areas of the South Site beyond the 200-foot contour were eliminated due to higher benthic productivity and higher species density. The deeper areas of the South Site would be used when ocean conditions prohibited transfer to the nearshore. The northern boundary of the South Site was established because of navigational safety conflicts with regards to the transfer areas used by the MCR bar pilots. The shoreward portion of the proposed South Site was located in the nearshore transport zone, an area of high wave energy. The material placed in this location would disperse and could feed the beach if placed in less than 60 feet of water. Dredged material placed in this area would be similar in type to existing sediment. The benthic organisms in this area are adapted to a high energy mobile environment and therefore, would be less impacted by dredged material disposal and subsequent sediment redistribution.
Due to the large number of comments from the public's review of the DEIS received from members of the Taskforce, reource agencies, and the public, the Corps and EPA convened additional facilitated meetings to discuss further refinements to the proposed ocean disposal sites.
The Corps and EPA revised the proposed North Site and South Site (Revision 1) by reducing the size of the North Site and the South Site. The deep water portion of the South Site would be used in the event that weather conditions or wave climate prevented access by the dredge to the nearshore sites while allowing for predominantly nearshore placement of material. The revised sites were still large enough to limit the impact from an individual dredging season to small areas on a rotational basis. Revision 1 was presented to the Taskforce on April 14, 1999. Many of the Taskforce representatives felt that the spatial extent of the proposed revised North and South Sites were still too large and impacts to the crab fishing industry would still be unacceptable.
The Taskforce was convened again on May 12, 1999, to discuss further revisions to the proposed disposal sites. The Corps and EPA fully supported and still support the concept of nearshore placement of material and view dredged material as a valuable resource that is beneficial to keep in the littoral zone. Further, disposal of material in the nearshore, in the active energy zone, would be less biologically impacting than disposal in deep water (depths greater than 200 feet). The site selection criteria require that sites be selected that minimize interference with other uses or activities in the marine environment including existing fisheries. Considering the disagreement between some members of the Taskforce and the EPA and the Corps as to the extent disposal in the nearshore areas (the originally proposed North and South Sites) would interfere with the crab fishery, the EPA and the Corps decided to propose the designation of a Deep Water Site. This site was viewed by the Taskforce, Corps, and EPA as minimizing this interference, although disposal in the Deep Water Site may result in more biological impacts than disposal in the near shore areas.
