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Coastal Planning & Engineering, In CAC March 13, 2008 New Business VIII-1 1 of 94 COLLIER COUNTY EMERGENCY SAND SOURCE EVALUATION Prepared for: Collier County Prepared by: Coastal Planning & Engineering, Inc. Charles W. Finkl, Ph.D. Jeffrey Andrews, PSM, CIH Melany Larenas, P.G. Beth M. Forrest, Ph.D. Recommended Citation: FINKL, C.W.; ANDREWS, J.; LARENAS, M. and FORREST, B.M., 2008. Collier County Emergency Sand Source Investigation. Boca Raton, Florida: Coastal Planning & Engineering, Inc. 25p. (Prepared for Collier County, Florida) February 2008 CAC March 13, 2008 New Business VIII-1 2 of 94 COLLIER COUNTY EMERGENCY SAND SOURCE EVALUATION Table of Contents Introduction......................................................................................................................... 1 Geological Background ...................................................................................................... 3 Equipment and Methods ..................................................................................................... 6 Investigation Sequencing.................................................................................................. 11 Results and Discussion ..................................................................................................... 21 Conclusions....................................................................................................................... 22 Acknowledgements........................................................................................................... 23 Literature Cited ................................................................................................................. 23 List of Figures Figure 1. Regional map showing the areas of investigation. .............................................. 2 Figure 2. Geometrics G-882 Digital Cesium Marine Magnetometer used to investigate magnetic anomalies within the potential sediment sources. ............................................... 8 Figure 3. EdgeTech X-STAR SB-216S used to conduct seismic reflection profile surveys. ............................................................................................................................................. 9 Figure 4. The BH-4 vibracore apparatus being deployed................................................ 10 Figure 5. Flow diagram showing the main phases of sand search investigations for the Collier County sand search. .............................................................................................. 12 Figure 6. Areas recommended for future investigation. .................................................. 16 Figure 7 a. Geophysical trackline and vibracore locations for the Gordon Pass Ebb Tidal Shoal and 1996 CEC Ridge Deposit potential sand resource areas.................................. 17 Figure 7 b. Geophysical trackline and vibracore locations for the southern portion of the 2002 CPE Ridge Deposits potential sand resource area. .................................................. 18 Figure 7 c. Geophysical trackline and vibracore locations for the Cape Romano Shoals potential sand resource areas. ........................................................................................... 19 Figure 8. Correlation of geophysical and vibracore data to determine the thickness of sediments and to ascertain the presence of undesired rock and/or material unsuitable for dredging. ........................................................................................................................... 20 List of Tables Table 1. Equipment used for this study. ............................................................................. 6 List of Appendices Appendix 1 2007 CPE Seismic Data (Digital Copy Only) Appendix 2 2007 CPE Vibracore Logs Appendix 3 2007 CPE Vibracore Photographs Appendix 4 2007 CPE Individual Vibracore Granularmetric Reports Appendix 5 2007 CPE Individual Vibracore Grain Size Distribution Curves/Histograms i COASTAL PLANNING & ENGINEERING, INC. CAC March 13, 2008 New Business VIII-1 3 of 94 COLLIER COUNTY EMERGENCY SAND SOURCE EVALUATION Abstract To meet the needs of future emergency beach nourishment projects, Collier County authorized Coastal Planning & Engineering, Inc. (CPE) to conduct reconnaissance level marine sand search investigations. During Phase I, a comprehensive review of the sediment resources offshore of Collier County was conducted to identify potential beach compatible sand sources for use in small emergency nourishment projects along the County’s coast. Five (5) main areas including the Gordon Pass Ebb Tidal Shoal, the 1996 CEC Ridge Deposit, the 2002 CPE Ridge Deposits, the Big Marco Pass Ebb Tidal Shoal and the Cape Romano Shoals were recommended for further investigation. The northern portion of the 2002 CPE Ridge Deposits and the Big Marco Pass Ebb Shoal were recommended for further review of existing data. The areas recommended for reconnaissance level investigations include the southern portion of the 2002 CPE Ridge Deposits, the Gordon Pass Ebb Tidal Shoal, the 1996 CEC Ridge Deposit and the sand ridges located off Cape Romano. Phase II investigations consisted of geophysical and vibracore surveys. The reconnaissance level investigation resulted in the identification of one (1) area that is suitable for further detailed investigation for development as an emergency borrow area. This area is recommended for further investigation although the shallow water depth and the distance to the recipient beach(es) should be considered during planning. INTRODUCTION To meet the needs of future emergency beach nourishment projects, Collier County authorized Coastal Planning & Engineering, Inc. (CPE) to conduct reconnaissance level marine sand search investigations. During Phase I, a comprehensive review of the sediment resources offshore of Collier County was conducted to identify potential beach compatible sand sources for use in small emergency nourishment projects along the County’s coast. Emergency nourishment projects that occur between major projects, often require small volumes of sand. These projects do not warrant a major dredging effort, and the disturbance associated with truck haul projects is undesired. Available historic investigation areas, potential sand resources and borrow areas were compiled and superimposed on NOAA bathymetric data. Geophysical and geotechnical data collected within these areas, as well as any reports discussing the findings, were then reviewed. Based on this analysis, a single map identifying potential deposits of beach compatible material was generated (Figure 1). Phase II investigations, which are the subject of this report, focused on these potential deposits. Phase II investigations consisted of geophysical and vibracore surveys. In August 2007, seismic reflection, magnetometer and bathymetric survey data was collected. In November 2007, vibracores were collected from the most promising areas. The sand resource areas that were identified were analyzed using GIS procedures that integrated the bathymetric survey, seismic reflection profiling and vibracore data to estimate deposit thickness and sedimentary characteristics. The reconnaissance level investigation resulted in the identification of one (1) area that is suitable for further detailed investigation in order to develop it as an emergency borrow area. 1 COASTAL PLANNING & ENGINEERING, INC. CAC March 13, 2008 New Business VIII-1 4 of 94 Figure 1. Regional map showing theareas ofinvestigation. Figure 1.Regionalmap COASTAL PLANNINGCOASTAL 2 & ENGINEERING , INC . CAC March 13, 2008 New Business VIII-1 5 of 94 This report summarizes the results of the offshore geophysical and geotechnical investigations that led to the identification of a potential sand resource area. Geological background and analysis of legacy data are discussed first, followed by a description of field activities, analysis of results from field measurements, and finally definition of the characteristics of the identified sand resources. Geographic Location Collier County is bounded to the west by the Gulf of Mexico, to the north by Lee and Hendry Counties, to the east by Broward and Miami-Dade Counties and to the south by Monroe County (Figure 1). Collier County covers an area of approximately 1,280,000 acres and has over 50 miles of coastline. GEOLOGICAL BACKGROUND Coastal Geological Framework A description of the geologic setting of the region is central to the understanding of bedrock seafloor surfaces and the sediments sitting on them. The nature of sedimentary deposits determines sand quality and its potential use for beach nourishment. It is, thus, helpful to understand the general shelf environments because the distribution of beach-quality sands on the seabed is not random, but spatially well defined in terms of stratigraphy, grain composition, age of materials and erosional-depositional events. The western coast of Florida is part of a large primary geological feature referred to as the eastern Gulf of Mexico Sedimentary Basin, which is further divided into the North Gulf Coast Sedimentary Province and the Florida Peninsula Sedimentary Province (SCHMIDT and CLARK, 1980). The Florida Peninsula, a large carbonate platform containing a thick, non-clastic sedimentary sequence predominantly composed of carbonates and anhydrites, was constructed between the middle Jurassic (180 MYA) and the late Miocene (5 MYA). This ancient carbonate platform forms the proximal portion of the west Florida shelf-slope system and exerts large-scale control on
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