San Leandro Marina Alts Study_Final

Home

3. Dredaed Materials shorebird habitat, the total dredging potential would be about 353,000 CY (204,000 CY at South Basin refugia, 89,000 CY at North Basin refugia, and 60,000 CY at DMMS). This would allow Marina operations to continue for about 12 years (125,000 CY for the initial episode, 105,000 CY for Episode 2, and 115,000 CY for Episode 3) after which a new disposal location would be needed or the harbor converted to one of the other reuse alternatives. For cost estimating purposes, it is assumed that the new disposal location would be at a regionally authorized in -Bay or upland site. Should the market for the material within the DMMS improve to the point where the County or other flood control or restoration end users would pay for the hauling off of the material, it may be beneficial to continue using the DMMS so the "island creation" could be stretched to perhaps one additional dredge cycle. Based on berths per acre planning data from the California Department of Boating and Waterways, half of the existing Harbor Basin can provide an approximately 185 -slip boat harbor assuming a minimum vessel length of 40 feet (at that point, a market analysis should be conducted to determine demand for berths). This strategy is being proposed to assist the City in maintaining boat operations for the next 10-15 years, until the area is fully developed. At that time the City could evaluate the possibility of revenue from the development supporting all/some boat harbor operations. Beyond that point in time, the Marina could potentially avail itself of existing regional disposal sites in the bay (upland or in -bay), where other Marinas would also be going, if economically feasible, or begin implementing Alternatives 2 or 3. Table 3-1, below, summarizes the dredge disposal timeline, while Figure 3-2, on page 3-4, provides a conceptual illustration of the Dredged Materials Disposal Concept. Volume Year (CY) 0 125,000a 4 105,000 8 115,000 12 105,000 16 115,000 20 105,000 TABLE 3-1 DREDGE DISPOSAL TIMELINE Disposal Location & Quantity (CY) DMMS So Basin" No Basin Other In -Bay 60,000 65,000 105,000 91,000 24,000 105,000 115,000 105,000 Assumption: 120 foot Channel width and a dredge depth of -5 feet MLLW, plus 1 foot over -dredge. South Basin would have capacity remaining, but it would not be necessary under this scenario to fill to capacity. a Because the Marina berthing area has not been dredged since 1997, this area will require additional dredging over that which would be required in future 8 -year cycles, for a total of 125,000 CY. San Leandro Marina Harbor Basin 3-3 ESA / 210461 Alternatives Study March 2011