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Resolution 132-1980 RESOLUTION # 132-1980 WHEREAS, the BOARD OF COUNlY COMMISSIONERS of M)NROE COlIDty, Florida, has received an application from Arthur Mannes to construct: 225 1.f. of riprap seawall (application drawing indicates about 150 1.f.) along an open water shoreline and excavate approximately 11,700 c.y. of spoil from a dredged channel measuring 100' wide and 1250' long x 10' MSL. Actual dredge distance is about 660'. Spoil is to be deposited on adjacent uplands. The channel will connect several existing artificial channels and will be used for commercial purposes. A levee will be constructed along the center of the proposed channel to allow movements of equipment and this levee will be removed as the channel is excavated. Runoff is porposed to be limited by levees, silt curtains and good practice. Fuel facilities will be constructed on the applicants upland as part of planned commercial marina. Six finger piers measuring 5' x 16' will be constructed from the riprap shoreline. The project site is located at the upper end of an embayment on the south side of Stock Island. Impacts to the basin in recent years include extensive filling, shoreline alterations, marina, channel and basin dredging and sulfur laden power plant htennal discharge. The basin opens into the Florida Straits to the South. Shoreline develop- ment in the area includes: commercial marinas, trailer parks, a power plant and a desalination plant. Water quality in this deadend embayment is poor, varies seasonally and has limited the existence of benthic vegetation in much of the bay. The shoreline proposed to be riprapped consists of mature black mangroves (Avicennia germinans) above and below M-IW with an extensive wrack line composed of decaying seagrass and algae and miscellaneous debris forming the substrate in front of this fringe. The applicants property is supposedly 100' wide at this point and measuring from what appears to be the landward property line this 100' ends landward of NEW. Sediments in front of this fringe are very soft, organic, and of an unknown thickness. The path of the proposed 100' wide channel would include a black mangrove island of several hundred square feet slightly offshorue from this shore I in. Out from the shoureline to be riprapped depths are about -3 to -4' MLWand irregular in a soft, unvegetated substrate and then shallow to the south to about -1'MLW again as soft, unvegetated bottom and continue for several hundred feet gradually sloping towards the previously dredged baybottom. Previous inspection of this sloping area revealed little benthic vegetation and soft sediments with an algae-periphyton surface layer. Previously excavated channels are most likely unvegetated with deep, soft silt sediments. Toward the entrance to this embayment sediments are more stable and consolidated and are vegetated by scattered patches of Cuban shoalgrass (Halodule wrightii) and turtle grass (Thalassia testudinum). Wave-wash from dominant winds probably tend to sort sediments to an extent that allows vegetation near the entrance to the bay while accumulations of soft sediments in the upper bay have limited attached vegetation in shallow water. It has been documented that the sulfurladen discharge from the adjacen tpower plant during the time that it was idscharged directly into the interior of the bay contributed to the demise of seagrass vegetation in a large portion of the shallow bay. Several years ago this discharge was routed by a semi-permeable hem to the entrance of the bay and newly fonmlate.d ~ll 4kely require that this berm be made impenneable. HopefullY this.. ilt,.al,low more stable conditions to develop within the bay aiftt.. ~~'( , . possibility of revegetation of shallow substrates. Portions of the area proposed to be dredged are within the impact zone of the original power plant plume into the bay and due to orientation of the site shoreline it is likely that impacts were also severe in the NW portion of the bay. Biological surveys of the impact of the power plant APPROVED ON ~'-3-io I~?> ..!IlOII BOOK ~ PAGE - :>3(, discharge since the construction of the berm have revealed that some revegetaiton by seagrasses is occurring in the interior of the bay on the shallow flats. The excavation of the proposed 100' wide channel through existing shallow flats will result in additional bottom discontinuities in this bay and remove any potential for continued revegetation for these areas. Levels of suspended sediments in this bay are high due to the extent of unvegetated, unconsolidated sediments and a dredged channel forming a bottom discontinuity here will become a trap for these suspended fine sediments. No potential for revegetation will exist in the bottom of thses channels due to reduced light penetration and accumulation of fine silt similar to what has re~llted from the excavation of adjacent basins and channels. Replacing the sloping, mangrove shoreline with a bulkhead will result in a severe trap for floating organic debris which will decay, settle out and form anoxic bottom sediments which will constantly degrade water quality in the general area. Presently, some of this debris is scattered across the sloping shoreline and into the mangrove fringe during periods of extreme high tide allowing decomposition which does not exert as severe a demand on the nearby water body. Usage of the area as a commercial marina would additionally involve a constant resuspension of sediments and organic matter in the area compounding the problems already discussed. .Methods proposed for excavation result in movement of suspended fine sediments that are very difficult to control during an operation of this type resulting in impact to shallow areas adjacent to the proposed dredge area. BE IT FURTHER RESOLVED, by the Board of County Commissioners of Monroe County, Florida, that said Board hereby given its approval for the construction of the above mentioned project. RESOL \lED this 3rd day of June , 1980, at a Regularly scheduled meeting. BOARD OF COUNTY COMvlISSIONERS OF MJNROE C , FLORIDA By (Seal) Attest: /~4i!~. ~AJI!""~ 8Y7~- Ntcm6y',Office ~$-?