including advance maintenance and overdepth dredging where applicable. Plan 1-42 also retains present advance maintenance criteria for Savannah Harbor. Total initial cost for Plan 1-42 is estimated to be approximately $38,539,000, including interest during construction. Average annual cost would be $3,496,100 and average annual benefits would be $5,432,900. The net benefits of the project would be $1,936,800 and the overall B/C ratio would be 1.6 to 1.

4.15 Plan 5-40. This plan provides for deepening the interior channel to -40 feet mlw from station 0+000 to 103+000, including Kings Island Turning Basin; deepening the bar channel from station 0+000 to 14+000B to -40 feet mlw; and deepening the bar channel from station 14+000B to 60+000B to -42 feet mlw. The plan involves use of towboats and dump scows (barges) to transport dredged material (approximately 971,185 cubic yards) to the ocean disposal site. A shuttle system would be made with tows and barges leaving the dredge and heading for the disposal site at regular intervals. Two dump scows would be handled by each towboat. Scows would have split hulls and be capable of bottom dumping at the disposal site. A mooring facility would be built to moor the scows and tows during non-working hours. Use of a convoy of tow boats and dump scows to constantly carry material to the ocean disposal site, as called for in Plan 5-40, has never been done in Savannah Harbor. It seems likely that due to the amount of traffic Plan 5-40 would generate and the narrowness of the channel, particularly upstream of the Fig Island Turning Basin, problems could arise with safety in the harbor and disruptions to shipping schedules. Plan 5-40 would have no effect on the existing system of upland disposal sites; however, it would result in a short term decrease in capacity of the existing ocean disposal area. This plan would have a greater impact on water quality at both the dredge and disposal site. The greater impact at the dredge site would be from the over flow filling of scows which would be necessary to efficiently perform the work and the greater impact at the disposal site would be from the use of unconfined disposal. The potential for cultural resource impacts would be the same as Plan 1-40 except for the potential impacts associated with dredged material disposal. Future O&M quantities from the interior channel would not increase significantly; however, additional O&M costs would be realized due to the increased monitoring effort which would likely be required at the ocean disposal site. Plan 5-40 assumes all maintenance dredging for the present 38 foot channel would be completed prior to new work dredging, including advance maintenance and overdepth dredging where applicable. This plan retains the present advance maintenance criteria for Savannah Harbor. Total initial cost for Plan 5-40 is estimated to be approximately $33,340,700, including interest during construction. Average annual cost would be $3,030,972 and

average annual benefits would be $4,529,500. The net benefits of the project would be $1,498,528 and the overall B/C ratio would be 1.5 to 1.

4.16 No Action. The adoption of this alternative means that nothing would be done to change existing channel depths and conditions in Savannan Harbor. This alternative obviously fails to meet planning obje tives since shipping delays and expenses would continue. The Savannah Harbor would not ncrease its efficiency for shippi: g and may lose a part of its competitiveness on the southeast coast. This would affect the local economy as well as that of the region and the State of Georgia. Vessels requiring a harbor deeper than -38 feet mlw would conduct their shipping operations at other ports. action would also mean there would not be any adverse impacts on fish and wildlife or cultural resources due to project construction. Salinity levels would remain at their present levels in the Savannah River.

No

4.17 The National Economic Development Plan (NED). Plan 1-40 is the NED Plan. This plan produces $1,108,800 more in net average annual benefits than Plan 1-42 and $1,547,072 more than Plan 540.

4.18 The Locally Preferred Plan. The Locally Preferred Plan is Plan 1-42. The sponsor believes that this plan is needed for the Savannah Harbor to remain a competitive port on the east coast. Their desire for this plan is indicated by their recent application for a Department of the Army permit to construct Plan 1-42 regardless of the outcome of the Corps' Feasibility Report. The State has also set funds aside for the possibly that the Georgia Port Authority would have to construct this project without Federal assistance.

4.19 Selected Plan. Plan 1-42 was examined closely during the detailed planning stage, and it was determined that it is the most responsive to local needs and desires while remaining within the guidelines established by Federal statutes. The reason the NED plan (Plan 1-40) was not chosen as the selected plan is that the local sponsor has agreed to pay the additional cost for dredging the material between -40 feet mean low water (mlw) and -42 feet mlw and Plan 1-42 would not result in any significant increase in environmental impacts. Plan 1-42 would deepen the interior harbor to an authorized depth of -42 feet mlw betw Stations 0+000 (river mile 0) and 103+000 iver mile 19.5), including Kings Island Turning Basin. Al new work material from the interior channel and Kings Island Turning Basin (4,375,142 cubic yards) would be placed in existing disposal areas. As with Plan 1-40, this material is mostly sand and could be used to improve and increase heights of the dike systems of existing disposal areas. Use of the terial for dike construction would extend the useable life of these areas. The bar channel would be deepened to an authorized depth of -42 feet mlw between station 0+000 and the end of the jetties (station 14+000B), then to -44 feet mlw between stations 14+000B (2.65 miles oceanward of river mile 0) and 60+000B (11.4 miles oceanward of river mile 0). This material (approximately 1,551,915 cubic yards) would be placed in the existing ocean disposal area. The impacts of Plan 1-42 are similar to those of Plan 1-40 except that Plan 1-42 will result

in an additional approximately .5 mile upstream shift in maximum salinity levels. However, our evaluation of this increase has resulted in a determination that impacts due to this salinity increase would not be significant. While Plan 1-42 would have a greater potential for impacts on cultural resources, these additional impacts can not be differentiated from the potential impacts for Plan 1-40.

5.00 AFFECTED ENVIRONMENT (WITHOUT PROJECT CONDITION).

5.01 Since filing of the Final EIS on the Savannah Harbor Deepening Project, authorization has been received to close New Cut and discontinue operation of the Back River tide gate. Construction of this project will result in changes in the affected environment chapter (Chapter 4.00) of the Final EIS. The discussions in the Final EIS on existing geography, climatology, geology and soils, hydrology, water quality, fishery resources, threatened and endangered species, wildlife resources, cultural resources, and economic environment would not be impacted by construction of the Section 1135. However, the paragraphs dealing with the impacts past harbor improvements have had on the environment (4.57 - 4.84) would change. discussion below will describe how construction of the Section 1135 Project will impact the environment and the resulting predicted condition.

The

5.02 The description of past Savannah Harbor Navigation Project improvements provided in the Final EIS would remain the same except for the elimination of the Back River tide gate from operation and elimination of the drainage canal (New Cut) which was constructed for operation of the tide gate. Elimination of these structures will result in shifts in the shoaling areas in the harbor which will result in increases in the costs of maintenance dredging due to increased pumping costs. The anticipated new shoaling areas are indicated on Figure 11. location of these areas was based on pre-tide gate data. volume of material removed from the harbor each year would remain the same.

The The

5.03 The immediate result of the Section 1135 action will be the lowering of salinity levels in the Savannah estuary which have resulted from past projects by from 5.0-6.0 ppt. Based on the LAEMSED Model predictions, closure of New Cut would in almost all cases lower salinity in the estuary. Table 2 and Figures 13-15 indicate the LAEMSED Model predictions for the maximum salinity levels which would occur in the Front, Middle, and Back Rivers after construction of the Section 1135 Project. Figure 12 indicates the river miles for Front, Middle, and Back Rivers used in the model runs.