Regular Workshop October 20, 2014 Agenda Item: Dr. Albert E. Browder, PE; Olsen Associates, Inc.

Transcription

1 Regular Workshop October 20, 2014 Agenda Item 8 Agenda Item: Presenter: Summary: Beach Update Town Manager; Dr. Albert E. Browder, PE; Olsen Associates, Inc. At the January 21, 2014 Regular Workshop Meeting, Olsen Associates Inc. (OAI) provided to the Town Commission an overview of the condition of the beach based upon 2013 shoreline survey data. In August 2014, we completed the annual monitoring and survey of the Town s entire shoreline. At the October 20, 2014 Regular Workshop Meeting, Dr. Albert E. Browder, P.E. of OAI will present and discuss the current condition of the beach and provide a report on project status and planning efforts to date. Attachments: Recommended Action: Memo, Public Works Director to Manager; PowerPoint Presentation. Pending discussion; provide direction to Manager.

2 MEMORANDUM Date: October 13, 2014 TO: FROM: Dave Bullock, Town Manager Juan J Florensa, Public Works Director SUBJECT: 2014 Beach Update At the January 21, 2014 Regular Workshop Meeting, Olsen Associates Inc. (OAI) provided to the Town Commission an overview of the condition of the beach based upon 2013 shoreline survey data. In August 2014, we completed the annual monitoring and survey of the Town s entire shoreline. At the October 20, 2014 Regular Workshop Meeting, Dr. Albert E. Browder, P.E. of OAI will present and discuss the current condition of the beach and provide a report on project status and planning efforts to date. The attached PowerPoint presentation discusses the following main items: Current Conditions Shoreline changes Status of beach relative to design conditions Update of sand volume needs Project Status & Planning Scenario of projects Current status of projects Suggested project timelines Next Steps This item is placed on the October 20, 2014 Regular Workshop Meeting for Commission review and consideration. Attachment: PowerPoint Presentation

3 Town of Longboat Key, FL Beach Project Update Town Commission Meeting Longboat Key, FL Dr. Albert E. Browder, P.E., D.CE Herschel St. Jacksonville, FL

4 Discussion Items Current Beach Conditions June 2014 Shoreline and beach sand volume conditions Status of beach relative to design condition Update of sand volume needs Project Status and Planning Scenario of Projects Current status of projects Next Steps 2

5 Recent Shoreline Changes July 2013 June 2014 Partially filled post survey WCIND Disposal Project 3

6 2014 Beach Conditions Gulfside Rd. 9 July 2014 South End 9 July 2014 Surveyed June 2014 WCIND Project 9 July

7 Current Shoreline Position (June 2014) Longboat Pass Longboat Key, FL 1" = 4,000 ft New Pass Gulf of Mexico geotext sill Islander PAGs BASELINE BASELINE BASELINE June 2014 MHW Shoreline 300 WCIND Project July 2013 MHW Shoreline ,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000 55,000 5 olsen associates, inc. Alongshore distance from Longboat Pass bridge (ft)

8 Current Beach Volume Conditions (June 2014) Longboat Key, FL 0 2,000 4,000 ft Longboat Pass New Pass geotext sill Gulf of Mexico Islander PAGs -100 Greer R-42 R-43 R-44 R-44.5 R-45 R-45.5 R-46A R-46.5 R-47 R-47.5 R-48 R-48.5 R-49 R-49.5 R-50 R-50.5 R-51 R-52 R-53 R-54A R-55 R-56 R-57 R-58 R-59 T-60 R-61 R-62A R-63 R-64 R-65 R-66 R-67 T-1 R-2 R-3A R-4 R-5 T-6 R-7 R-8 R-9 R-10 R-11 R-12 R-13 R R-14 T-15 R-16 R-17 R-18 R-19 R-20 R-21 T-22 T-23 R-24 R-25 R-26 R-27 R-28 R-28.5 R-29 terminal groin <----surplus Sand Volume Density (cy/ft) deficit -----> July 2013 Conditions Volume above -6 ft Deficit of sand Surplus of sand narrower beaches July 2014 sand volume relative to design beach condition VOLUME ABOVE -6 ft ONLY <- WCIND Project -> wider beaches Deficit of sand 6 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000 55,000 olsen associates, inc. Alongshore distance from Longboat Pass bridge (ft)

9 Sand Volume Requirements *To restore design in and provide 8 years of advance nourishment North end**: 6633 GMD seawall/gulfside Rd.: Central island: South New Pass: 50,000 cy 350,000 cy 210,000 cy 315,000 cy 925,000 cy* ** dependent upon PAG installation and performance 7

10 Construction Scenario C Longboat Pass, New Pass, and Truck Haul Considerations relative to Scenario A: Maximizes flexibility of timing and placement Significantly reduces sand quality concerns New Pass dredging permit/agreement required Requires trucking Lowest overall cost (34% to 38% less than A) 8

11 Since January 2014 Scenario C is essentially underway Beach conditions updated in June 2014 (discussed above) WCIND project constructed at North End (May-July 2014) North End PAG project about to commence Longboat Pass dredging permits have advanced New Pass dredging permits have been applied for Interim South End sand placement under development FDEP grant has been modified to follow this scenario 9

12 Suggested Project Timeline Lots of truck hauling dredging would be better 10 SOUTH END CENTRAL ISLAND GULFSIDE ROAD NORTH END SOUTH END CENTRAL ISLAND GULFSIDE ROAD NORTH END

13 Beach Disposal from New Pass Obtain sand from USACE channel Placement along south end ~Beachplace to Sands Point Application submitted 1 August 2014 Inlet Management Plan required Would not delay construction by Town Construction Anticipated Subsequent dredging by Lido Key ~5-6 year cycle expected NOT FOR NAVIGATION PURPOSES 11

14 South End Interim Sand Placement Purpose: Dune protection Maintain beach width Interim measure until New Pass disposal Tentative Construction: Spring

15 Schematic ~25,000 cy along 3,800 ft: 6 7 cy/ft 13

16 Upland Sand Mines Orlando Davenport multiple sites Tampa Sebring LONGBOAT KEY Google Earth * on-road distances specific routes not determined 14

17 Truck Haul Beach Construction Sand mine PAFB Feb 2011 Kelly Palm Beach Daily News PAFB Feb 2011 PAFB Feb

18 Truck-Haul Sand Placement (1 of 2) For 25,000 cy: roughly 1,500 truckloads 1,000 cy/day up to 1,500 cy/day production from Central Florida 90 trucks/day -----> 9 trucks per hour One truck every 6 minutes 16 to 25 construction days (6 days a week) Cost opinion: ~ $1.4 million $40 to $45 per cubic yard in place 16

19 Truck Haul Sand Placement (2 of 2) Additional issues Access corridor(s) Road/bridge restrictions under review Regulatory agencies contacted for Notice-to-Proceed Investigating alternative delivery methods Sand source remains Central Florida mines 17

20 North end Next Steps (1 of 3) Implement North end structural stabilization project Assess initial shoreline response from PAGs Observe & support Longboat Pass maintenance permitting 6633 GMD seawall / Gulfside Rd. Observe & support Longboat Pass maintenance permitting Develop plan for sand placement 18

21 Central island Next Steps (2 of 3) Consider renourishment via truck haul from Central FL Develop plan for selective sand placement 4795 Gulf of Mexico Dr. to Islander Club/Villa de Lancia Currently permitted for this activity South end Complete the revised New Pass sand sharing agreement Complete New Pass beach disposal permitting Develop plan for sand placement 19

22 Next Steps (3 of 3) Update Beach Management Plan Last updated in 2008 Codify revised beach segments Incorporate recent shoreline conditions North end erosion Coastal structures implementation Evaluate design condition relative to storm vulnerability Set future expectations and objectives Seek additional offshore sand sources Conduct geotechnical sand search for new sources Refine (reduce) existing sites to address constructability Evaluate long-term viability of inlet/truck haul sources 20

23 Suggested Project Timeline Lots of truck hauling dredging would be better 21 SOUTH END CENTRAL ISLAND GULFSIDE ROAD NORTH END SOUTH END CENTRAL ISLAND GULFSIDE ROAD NORTH END

24 New Pass Channel Inlet sand sources Permitting underway Shared with Lido Key Longboat Pass Channel Permitting underway Shared with Anna Maria Isl. Longboat Pass flood shoals Smaller volumes potentially available All are considered supplemental sources Shared sources, slow regeneration 22

25 Existing Offshore Sand Resources Sand quality concerns Grain size/compatibility Shell/carbonate content Variability within sites Color 23

26 Thank You Dr. Albert E. Browder, P.E., D.CE Herschel St. Jacksonville, FL New Pass (FDEP photo) 24

27 End of Agenda Item