7.0 ASSESSMENT OF ALTERNATIVES TO PROJECT

7.1 Dredging

This dredging activity is part of a larger project involving the total development of the Port of Kingston in order to maintain the port’s competitiveness. Shipping activities have increased very significantly over the past five years. Further, the vessels are getting longer and the average number of containers per vessel has also increased.  In the region as a whole shipping activities have doubled over the past five years, and it is anticipated that this activity will triple within the next 10 years. The capacity of the largest container ships (a function of size) has almost doubled in the last five years. It is expected that the Port of Kingston will have to accommodate vessels of this size within the next decade. If the port is not developed to handle these larger vessels and position itself as one of, if not, the major port in the region, it stands to lose some of the current clients to other ports which are currently carrying out development (e.g. Jacksonville, Fort Everglades, USA; Manzanillo, Cristobal and Balboa in Panama, San Juan in Puerto Rico, and Rio Haina in the Dominican Republic).  It is therefore critical to the continued success of the Port of Kingston that the development project should continue. The dredging of the channel would ensure that the longer vessels now coming on stream could be accommodated in the Port of Kingston. This is a preferred alternative.

7.2 No Dredging

If the channel is not enlarged to accommodate the larger vessels now in use (and those anticipated) over the short to medium term, the Port of Kingston would lose clients. This would have a significant negative effect on the Jamaican economy.  This alternative is not preferred.

7.3 Alternative Disposal Sites

The perceived impacts from the spoil disposal alternatives are positive and negative, as well as national and local in nature:

Alternative 1:    Place all of the dredged material in the proposed Hunts Bay reclamation platform

Alternative 2:    Dispose all of the material at a suitable marine site

Alternative 3:    A combination of the above options with some material being placed in the Hunts bay Reclamation platform or some other land bank location

7.3.1    Reclamation

7.3.1.1 Disposal on land

This alternative assumes disposal at a site that affords protection of ground water and isolation to prevent entry of contaminants into the food chain. While this option can provide precise control over the fate of contaminants, there are a number of factors to consider which would influence cost. These include site identification, site preparation, ground transportation and security. It is expected that the less contaminated material could also be used generally as fill without any serious environmental risk. The possible risk from resubmergence of toxic spoil as a result of some catastrophic “act of God” cannot be overlooked. Although the effect would be immediate and negative, its magnitude would also be impossible to predict. It is likely that a lot of other collateral damage would also occur.

7.3.1.2 Disposal at Hunt’s Bay

Disposal to a section of Hunt’s Bay would provide little or no dilution and could be a significant short–term and long-term source of lead and sulphide to the rest of the bay. Through an engineered solution it may be possible to confine the sediment physically thus eliminating the impact from suspended solids. Preventing leaching to adjoining areas would be more difficult. This alternative would also result in further but marginal loss of habitat in addition to the area to be filled for the port expansion. Terrestrial vegetation lost during this activity would be ecologically insignificant.

With respect to land tenure, the land had been vested by the Commissioner of Lands to the PAJ.

Discussions with representatives from the Town Planning Department (TPD) and KSAC indicated that the proposed land use of the reclaimed land would be compatible with surrounding land uses. Once the land was reclaimed, a Site Plan should be developed by PAJ and sent to the TPD and KSAC. Potential impacts would be localized positive impacts related to ‘new’ lands being brought into use and national positive impacts related to the future development of port and transshipment activities and associated economic gains.

As pointed out in the Feasibility Study, the stability of the existing Causeway Bridge needs to be safeguarded and the alignment of the future Causeway Highway needs to be considered. The pre-feasibility study for the new Causeway Highway was done more than 4 years ago including a proposal for the resettlement of the dwellers, fishing community and vendors. It was further understood that the PAJ had been in discussion with the Highway 2000 Team at the Ministry of Transportation and Works, and was given the ‘green light’ to proceed with works in the vicinity of the bridge, as the construction of highway would ‘work around’ the proposed development. [1] Therefore, depending on whether the measures to be implemented by the Ministry of Transportation and Works are done in a timely manner, then potential impacts should be negligible. If not implemented on time, then potential impacts would be negative, short term and direct, until such time that the measures were put in place.

In addition, while fishing activities are minimal at the proposed reclamation site, the westward drift of the plume should be carefully monitored as it could negatively impact handline fishing activities on the western side of the bay. Also, given the composition of the material that would be dredged, and the fact that only a portion of the more compact and non-toxic material may be suitable for land reclamation, the rest of the material would have to be otherwise disposed.

7.3.2    Offshore Disposal

Disposal at sea alone would remove the economic benefits to be gained from land reclamation. It also introduces the complication of the possible effect that toxic substances might have on  marine benthic and pelagic flora or fauna. Increased levels of bio-accumulation in these organisms may have immediate or deferred mortality impacts. This alternative would be the least favourable.

7.3.2.1 Offshore Disposal - 200 metre depth contour

A minimum dilution factor (worst case) based only on volume of receiving water and ignoring the dispersive effect of currents was determined to be around 100-fold. Assuming negligible contribution from the receiving water, and using the results of sediment/leachate analyses, maximum temporary contribution of lead from sediment deposited at the dump site could be around 0.5ppm (500ppb), while sulphide could be 5mg/l, and BOD 10mg/l.  Based on the total material to be disposed of, average suspended solids could be 6mg/l. It is considered that factors such as prevailing currents as well as interval between discharge events could lessen these values considerably.

7.3.2.2 Offshore Disposal - 1000 metre depth contour

A minimum dilution factor (worst case) is determined to be around 1000-fold. Using similar assumptions as in the 200m analysis, it is suggested that a further reduction of at least one order of magnitude would be achieved. It is also likely that at this greater depth, oceanic currents would enable a greater level of dilution. The greater distance that would have to be travelled by the dredge would also provide a longer period between discharge events thus improving dilution even further.

If dumping of the spoil from the Gordon Cay/container port sections H5 to H1 is to occur between the Hope River outfall and Cow Bay, then this heavy metal-polluted material must be placed into very deep water (not less than 1,000 m) and as far south as is feasible in terms of travel time for the barge.  This is to avoid the displacement of resident fish species. Cow Bay is known for deepwater fishes such as dolphinfish, kingfish and jacks, and is the site of a very small fishing beach.

The heavier fractions will make up the mound of consolidated material and this will be thinner and cover a larger surface area, than if dumping were to take place at 200m.  This could result in the complete leaching of all the contaminants from the mound to the surrounding waters taking place in a shorter time. Some finer fractions of the plume may become neutrally buoyant at depth and travel with the prevailing current at that depth.

Other parameters necessary for model input such as temperature, salinity, current regime stratification, have not been measured at these depths, and so we must consider the greater spreading as the worst case scenario.

7.3.3 Mixed Land/Sea disposal

This scenario assumes disposal of the more contaminated material on land at an adequately prepared site, and “clean” material in the marine environment. This assumes that the contaminated material is surface sediment, and that the quality of sediment improves with depth. For this option dumping could be at the 200m or 1000m contour.  This option would be expected to have a minimal environmental impact especially where marine disposal is to the 1000m contour. 

Based on the foregoing discussions, this alternative would be the most favourable. This option would take into consideration the concerns of the fishing communities, provide additional land space for the further development of container storage with significant potential economic benefits, and facilitate the disposal of toxic materials in a location that would not negatively or minimally impact on the livelihoods of the surrounding communities under normal circumstances.