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investigations and analysis of the investigation results to determine the preferred location for the placement of the mitigation reef. Several transcontinental fiber optic cables are present in the Vero Cove area , originating onshore and extending across the mitigation reef site in an east-west direction . The location of the cables will be identified based on existing information , and included as part of the mitigation reef placement siting determination . Task 1 . 1 . 1 Bathymetric Survey and Set Tide Gauges for Water Surface Elevation Prior efforts for similar work indicate the necessity of establishing track line geometries in both shore-parallel and shore-normal orientations . A trackline spacing of five hundred (500) feet on-center in the shore-normal direction , and 'cross' lines at three hundred (300) feet shore-parallel is proposed . The first shore-normal trackline shall commence directly offshore from DEP monument R-86 at an approximate water depth of 12 feet (MLLW) and shall extend a maximum of 2 , 000 feet offshore . Shore-normal tracklines shall occur parallel to the R-86 trackline at 500 foot spacing along profile azimuths appropriate for the area/consistent with DEP historic data offshore of DEP reference monuments R-86 through R-95 , inclusive . Half- station transects will be established between identified reference monuments by creation of a baseline , such that R-86 . 5 through R-94 . 5 , inclusive , are the resultant transect lines. The 19 shore-normal tracklines described shall cover approximately 7 . 2 line-miles . The shore parallel tracklines shall be conducted beginning offshore of R-86 at an approximate water depth of 12 feet (MLL" . The shore parallel tracklines shall be taken every 300 feet and shall extend a maximum of 2 , 000 feet offshore . Shore-parallel tracklines shall extend alongshore to R-95 (a total shore parallel length of approximately 8, 500 feet) . The 7 shore-parallel tracklines shall cover approximately 11 . 93 line-miles . Bathymetric measurements of the offshore topography will occur simultaneously with the sub-bottom profiling (Task 1 . 1 . 2) . The deliverable for the bathymetric survey task will include reduced tide-corrected data delivered in electronic format and on a contour plot . Based on prior work experience , it will be necessary to set one tide gage to allow for accurate correction to acquired bathymetry. Florida Department of Environmental Protection Reference (R-) monuments will be checked and the monuments field-located to establish horizontal and vertical control for the tide gauge to be deployed . The tide gage shall be set offshore of monument R-90 as near as possible to mid project . The final location of the gauge will be subject to field reconnaissance , monument location , and substrate conditions . The gauge will be installed in water depths sufficient to conduct vertical leveling in coordination with a shore-based survey crew. Bar check calibrations of the survey fathometer will be performed daily throughout the field operation , and will be conducted in accordance with prescribed USACE standards for hydrographic surveying , to ensure that accurate water depth data are being acquired . For the shore normal and shore parallel trackline surveys the ATM project team will utilize ATM's 25' Parker survey boat, an Odom Hydrotrac Fathometer, and a Trimble Differential Global Positioning System (with the fathometer and DGPS interfaced to HYPACK hydrographic software) . CAWINDOWS\TEMPWnbersend Post-Construction Services Contract Amendment N6 - Reduced Scope 03-12M.doc 2