Conceptual Engineering Report Collier County Beaches, Florida Presented to Collier County Coastal Advisory Committee October 13, 2011 Steve Keehn, PE, CPE
Topics Goals Monitoring & Performance Summary 3 Major Hot Spots Findings Modeling Results Recommended Project Combination of Existing and New Practices Cost and Cost Saving Next Step
Goals: The purpose of the study was to develop conceptual designs that addresses the effectiveness of existing structures and beach fill design templates, and changes needed to solve hot spots and improve project performance and durability. Beach fill alternatives with a higher and wider beach berm were evaluated with structural modifications to achieve these goals.
Hot Spot Ranking Matrix Hot Spot Erosion Rates Maintain Beach Width Groin Impacts Hardbottom Limitations Management Practices Relative Importance Code Barefoot Beach R14-R16 XX NA X 3 M, N Delnor Wiggins State Park X 1 I Vanderbilt Beach R27 & R31 X X X 3 S, * Pelican Bay R35-R36 X X 2 I Clam Pass Park R42-R44 XX NA X X 4 M, N Seagate Drive R45-R46 X X X 3 S & G Park Shore R51-R54 X X X 4 S, * South of Doctors Pass R58 XX XX X X X 7 M, Str South of Lowdermilk Park R62-R64 X X X 3 S & G South Naples R71 XX 2 I Code S More sand or feeder beach likely solution G Shorten or remove groin likely solution M Management change needed Str New structure needed N Nourishment I Not a problem * Structures as fall back solution Priority Yellow, blue, green.
Major Finding The performance of the beach in avoiding hardbottom coverage has exceeded permit expectations, and the results of four years of physical monitoring indicate that the beach can be widened without a significant increased risk of hardbottom impacts. The analysis and modeling indicate that the recommended plan with a 10 year project life is feasible with the use of minimal new structures.
Bases of Conceptual Design Excellent Performance 25 ft. advance at MHW Versus 37 ft. retreat at -11 ft. NAVD 63 feet Total Advanage 25.0 Park Shore Hot Spot Solution
CHANGE INLET MANAGEMENT MODIFY DISOSAL AREA COORDINATE INLET MANAGEMENTND AND BEACH NOURISHMENT ELIMATE/REDUCE STRUCTURES (Groins) Return Disposal Area Here, but Upland South of Doctors Pass Extend Disposal Area to Here Clam Pass Park and Seagate Drive
In general, if sufficient sand can be placed on the beach through nourishment and inlet bypassing, then a structures are less important.
Much Sand and No Structures Better Beach
Alternatives Considered Alternative 1: FEMA Project Alternative 2: 2006 Project w/ 3 Reaches Alternative 3: 2013-14 Design with 10- Year Life in 5 Reaches Higher and Wider Beach Alternative 4: Structures Removal Modification
Summary of Modeling Results and Final Plan In general, the modeling shows a 10-year nourishment interval is feasible and most of the groins can be removed, resulting in improved performance of the beach. Modeling shows that a wider fill placement and removal of some of the existing structures is the most practical and direct solution, while many of the structures modeled had less convincing performance.
Calibration for Vanderbilt Beach
Naples with and without structures after 3 years
Aerial photography dated of 2008 and 2009 taken at the Double pipeline outfall and groin combination
Park Shore with and without structures after 3 years
The 2013-14 design without structures is the recommended plan, in conjunction with increased sand placement near hot spots identified by the modeling. This selection is a combination of Alternative 3 and M9 to M11. For economy, gaps in fill placement should be allowed in the project area to reduce the amount of fill needed and its associated cost.
10-Year Life Add n Fill @ R-29 Gaps Vanderbilt Recommended Plan
10-Year Life Remove Structures Modify Bypassing to R45 Gaps Park Shore Recommended Plan
10-Year Life Remove Structures Modify Bypassing Disposal Build Groin Spur Gaps Naples Recommended Plan
Net Sediment Transport with and without Spur & Volume Gain
If sufficient sand can be placed on the beach through nourishment and inlet bypassing, then a structural solution is less important. In general, the modeling shows a 10-year nourishment interval is feasible and most of the groins can be removed, resulting in improved performance of the beach. Modeling shows that a wider fill placement and removal of some of the existing structures is the most practical and direct solution, while many of the structures modeled had less convincing performance. The consideration of new structures should also be delayed until sufficient monitoring of the expanded project is performed.
DESIGN VOLUMES REACH Vanderbilt R22 to R31 N. Park Shore R45 to R48 Park Shore R49 to R55 DESIGN VOLUME (C.Y.) ALT. 1 ALT. 2 ALT. 3 40,000 41,733 58,056 21,000 40,881 49,729 30,000 97,251 136,337 Naples Beach 84,000 302,166 413,008 R58A to R79 SUBTOTAL 175,000 482,031 657,130 Barefoot Beach 100,000 R14 to R16 Clam Pass R42 to R44 30,000 TOTAL 175,000 482,031 787,130
Recommended project: Combination of existing practices and new alternatives using 2013-14 Design Alternative 3 without structures and modification to inlet management practices Continuation of Existing Practices. Beach fill Vanderbilt Beach R22.5 to R31.5 Park Shore R45.5 to R54 Naples Beach R58 to R79 Inlet Bypassing at Wiggins, Clam and Doctors Passes
New Elements Widen & raise the beach to support a 10-year life. Nourish Barefoot Beach (R14 R16) and ebb shoal. Nourish Clam Pass Park as feeder beach for Park Shore. Return to pre-2005 disposal area for Doctors Pass dredging Remove structures from beach sequentially from those with the largest impact, lowest cost and easiest to address outfall solution. Start with the structures located closest to Clam and Doctors Passes. Add a spur to the south Doctors Pass jetty Delay other structures
Higher & Wider Profile Typical Naples Beach Profile 2006 vs 2010 Template Comparison 8 6 4 2010 Profile 2006 Template Expanded Template Elevation (ft, NAVD 2 0-2 10 1 15 10 1 1-4 -6-8 -10 50 100 150 200 250 300 350 400 450 500 Distance (ft)
Gaps No Fill Needed R-22 to R-24 R-50 R-66 to R-69 R-31 R-54 R-73 to R-75 R-49 R-55 R-77 to R-79
Groin Removal Remove Groins In Sequence North to South starting with: Three groins South of Clam Pass Vicinity of R44.5 & R45.5 First 2 groins South of Doctors Pass R58 & R59+300
Cost and Cost Savings
Price Estimate Item Alt. 1 FEMA Design Alt. 2 Existing Design Alt. 2A Existing Design Alt. 3 10-yr Nourishmen t Interval Fill Volume 175,000 482,031 612,031 787,130 Fill Cost for 2006 Project Limits $9,218,501 $18,497,995 $18,497,995 $24,345,324 Barefoot and Clam Pass Parks $0 $0 $3,751,300 $3,751,300 Structure Modification & Removal $0 $0 $400,000 $1,600,000 Design, Permit & Monitoring $906,950 $906,950 $1,265,301 $1,490,987 Sub-total $10,125,451 $19,404,945 $23,914,595 $31,187,611 Potential Savings -$1,233,490 -$1,818,586 -$2,016,322 -$2,850,000 Reduction to 8-Year Proj. Life $0 $0 $0 -$2,764,001 5% Contingency $444,598 $879,318 $1,094,914 $1,278,680 Total $9,336,559 $18,465,677 $22,993,187 $26,852,290
Optimizing Project Cost. Schedule and Synchronize Coastal Components & Management Bidding and Contract Methods Administrative Technical Refine Design New Programmatic Biological Opinion
Schedule and Synchronize Coastal Management in County Inlet Dredging Beach Nourishment Beneficial Use of Sand Joint use of restricted disposal areas. Combine similar projects Marco, Caxambus and Doctors Pass
Savings Bidding and Contract methods Joint Project with bidding guarantees. Use unit price to manage sand volumes and cost Early availability of draft Plans and Specifications Partnered Maximize dredger time and flexibility Include best weather months in construction period. Highest dredge availability Best weather during sea turtle season Year Round Dredging Including Calmer Months
Complementary Tasks Outfalls Pipes Permit Issue Hot spots stays until outfall solved. Make changes to Inlet Management
New Programmatic Biological Opinion Allows Year Round Construction
¼ Mile Long Submerged Pipeline Being Emplaced Needs a Flat Water Day
2006 Construction Overview 92 days (60 Days Pumping) 8.2 miles of beach 664,000 CY construction volume Borrow area 33 to 38 miles away Equipment Great Lakes Dredge & Dock Company - 2 Hopper Dredges - 2 offshore booster pumps - 3+ miles of subline - Pipeline collars over reef areas
Environmental Monitoring Seek Reduction In Monitoring 14 miles of reef characterization Over 500 acres of hardbottom survey using Side Scan Sonar Diver edge verification Digital video documentation and reef data collection over 36 permanent monitoring transects, each 150 meters in length. Hard coral census and stress level assessments Complex and thorough marine resource investigation that it is ongoing annually for the next 3 years, then every other year until 2011.
Next Step Set Schedule Meet with FDEP Start Design & Permit Modification Develop Cost Saving and Bidding Plan Negotiate Reduced Monitoring Implement Plan
Task to Implement Project Permit Design, Plans and Specification for 2013-14 Project Pre-Application Meeting FDEP Map 3 New Pipeline Corridor and with Dredge Operational Areas Special Design Survey for Profiles, Structures, ECL & 3D Design Elements 3-D Design Update (around hardbottom) with larger fill section and new reaches Design Clam Pass Park and Barefoot Beach Address Hot Spots and Hardbottom Avoidance with intermediate profile line Run model with refinements and to revalidate design and Spreading magnitude Design structure modifications and removals Prepare BOEM Environmental Assessment Prepare & submit permit modification to 2005 Permit with new Permit Sketches RAI Cycle with Meetings Update biological and physical monitoring plans Develop Hardbottom Impact Assessment Develop Plans and Specifications Bidding and Award Pre-, During- and Post-Construction Task Pre-Construction Survey & Biological Monitoring Hardbottom mapping using side scan Construction Services Pipeline Corridors Monitoring Shore Bird Sea Turtle Monitoring Post-Construction Survey, Report and Certification Post-Construction Biological Monitoring and Report
The End