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2 Briefing Purpose To provide an update of the existing condition of the Portsmouth Seawall and to indicate the status of future projects

3 Seawall Description Overall Image of Portsmouth Seawall

4 Seawall Description Constructed in the 1970’s  Section adjacent to Holiday Inn constructed in 1981 Approximately 2480 linear feet, excluding High Street and North Landing Four segments – City Hall, Admiral’s Landing, Renaissance Hotel and Holiday Inn Majority of seawall is sheet pile and batter pile design Holiday Inn segment is sheet pile with tiebacks and deadman design

5 Seawall Description Image of Sheet Pile and Batter Pile Design

6 Seawall Description Image of Sheet Pile and Tieback/Deadman Design

Seawall Description Image of Sheet Pile with a batter steel H pile design 7

Installed Batter Steel H Piles 8

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10 City Hall Segment Image of City Hall Segment

11 City Hall Segment City Hall to High Street Landing Approximately 900 linear feet 20-30% material loss, which is consistent with its age Scheduled pile repair in summer of 2013  City Hall to North Inlet  Approximately 20 piles  Miscellaneous concrete repairs and pile replacement

12 Admiral’s Landing Segment Image of Admiral’s Landing Segment

13 Admiral’s Landing Segment High Street Landing to Lightship Museum Approximately 470 linear feet In 2010 approximately 150 linear feet failed because of failed batter piles  Batter piles in the failed section had approximately 75% material loss judging from piles that were removed during the project  Remaining batter piles were inspected  Most were found to have about 30% material loss  Sheet piles were inspected and have similar material loss (30%)

Pictures of Reconstruction of Failed Section of Seawall in 2010 Failed section of a batter pile 14

15 Renaissance Hotel Segment Image of Renaissance Hotel Segment

16 Renaissance Hotel Segment Lightship Museum to North Landing Approximately length 460 linear feet Timber piles under decking at north inlet (southern corner) need replacement  Some dolphin piles at this location also need to be replaced  Replacement included in upcoming project 2010 inspection revealed that steel batter piles were rusted and showing signs of deterioration  Section loss of 25-30%

17 Holiday Inn Segment Image of Holiday Inn Segment

18 Holiday Inn Segment North Landing to Tidewater Yacht Club Approximately 650 linear feet Inspection performed in 2006  Average material loss of 30%, some sections have loss of 40-50%  Deterioration of fenders and similar pile deterioration as other parts of seawall Started design for replacement in 2009

19 Holiday Inn Segment (Cont.) Discovered significant riprap outboard of seawall in 2011  Underwater inspection conducted in December 2012  Riprap extend 15 feet into channel  Requires design revision – seawall cannot be installed seaward Current exploratory investigation to verify location of tiebacks and deadmen  Information used to finalize design for replacement  Estimated replacement cost of $3.5 million dollars

20 Condition Summary City Hall and Renaissance Hotel Segments show deterioration expected due to age of structure – approximately 30% Admiral’s Landing Segment has experienced areas that have exceeded the expected rate of deterioration (section failure in 2009)  Pile replacement scheduled for this summer Holiday Inn Segment has a different design that the remainder of the seawall  Deterioration of 40-50% in some locations  Riprap found seaward of structure will alter design and increase replacement costs

21 Previous Seawall Projects Six Repair/Improvement Projects Since 1997 Repair to Seawall and Boardwalk Marine Improvements at Downtown Seawall and North Inlet  Installation of 9 dolphins in front of Downtown Seawall  Removal and replacement of copper pile caps and fender guards at North Inlet Structural Repairs to Seawall Decking North Landing Ferry Dock Repairs and Improvements Repairs to Portsmouth Seawall Boardwalk Seawall Repairs (Admiral’s Landing Section)

22 Recommendations Proceed with pile replacement project this summer Complete investigation of Holiday Inn Seawall and finalize design based on findings Re-inspect seawall from North Landing to City Hall  Determine repair options and inspection schedule based on results Estimated cost to replace seawall from North Landing to City Hall: $20 million (minimum)

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