Sediment Dispersion Modelling Clause Samples

Sediment Dispersion Modelling. At the time of preparing this Method Statement, the detailed planning for the locations and phasing of the CMPs within the key area for potential CMP development is being developed. Based on past experience with CMP operation, it is expected the worst case scenario for sediment dispersion modelling would involve concurrent dredging, backfilling as well as capping at three CMPs. While the sequence of construction and operation of CMPs is not determined at this stage, for the purpose of water quality modelling of worst case scenario, it is conservatively assumed the most contaminating activity (backfilling) would be conducted at the northern CMP, followed by the second contaminating activity (dredging) at the middle CMP, and the least contaminating activity (capping) at the southern CMP. Given the layout design of the CMPs is yet to be available, it is conservatively assumed that the sediment sources from the three CMPs for dredging, backfilling and capping would be aligned near the eastern edge of the key area for potential CMP development as shown in Figure 3.1 to conservatively assess the potential maximum cumulative impacts taking into account nearby concurrent projects (further explained in Section 6). It is conservatively assumed the least contaminating activity (i.e. capping, which is done with clean sediment and therefore no contaminant release) would occur at the southernmost CMP so any released contaminants from dredging and backfilling would have the longest retention time within ▇▇ ▇▇▇▇▇▇. Also, the sediment sources are assumed to be close to the eastern edge of the CMPs to assess the worst case impact towards the nearest WSRs at Lamma Island. Based on this arrangement, it is assumed the southernmost CMP would be used first, followed by the northernmost CMP, then the middle CMP. As such, the worst case scenario would assume backfilling at the northernmost CMP, dredging at the middle CMP and capping at the southernmost CMP to be conducted concurrently. For dredging at the middle CMP, either one trailing suction ▇▇▇▇▇▇ dredger (TSHD) with a working rate of 256,200 m3/week or two grab dredgers with a total working rate of 100,000 m3/week would be deployed. The sediment source(s) is assumed to be located close to the eastern edge of the key area for potential CMP development. Based on the typical arrangement of the existing CMP, disposal barges are typically instructed to dispose of sediments within the CMP area and located at least 100 m away from t...