Pier_Inspection_Report.pdf

PIER INSPECTION REPORT

FIRE ISLAND LIGHTHOUSE DOCK

FIRE ISLAND NATIONAL SEASHORE

Report prepared for: Report prepared by:

Federal Highway Administration Volkert, Inc.

Federal Lands Bridge Office 3809 Moffett Road Bridge Inspection and Management Program Mobile, Alabama 36618 21400 Ridgetop Circle Sterling, Virginia 20166 http://www.efl.fhwa.dat.gov/FLHBO/BIP

INSPECTION TYPE: IN-DEPTH

INSPECTION DATE: 5/11/2013

STRUCTURE SUMMARY FIRE ISLAND NATIONAL SEASHORE

FIRE ISLAND LIGHTHOUSE DOCK INSPECTION DATE: 5/11/2013

OVERVIEW

The Fire Island Lighthouse Dock is located at the Fire Island National Seashore near Islip, New York. Based upon 2013 aerial photography from Google Maps, the timber dock extended from a boardwalk 228.1’ into Great South Bay. However, at the time of this inspection, the dock had sustained heavy damage as a result of Hurricane Sandy, which affected the area on October 29, 2012. The boardwalk leading to the dock had also sustained heavy damage; however, most of the damage appeared to be the result of a fire. The overall length of the “J” shaped dock was measured to be 307.1’. A row of mooring pile clusters were located off of the east side of Spans #27 through #29.

INSPECTION

In accordance with OSHA 29CFR Part 1910, Subpart T, the ASCE Manuals and Reports of Engineering Practice No. 101: Underwater Investigations Standard Practice Manual, and the Volkert Underwater Inspection Manual, an underwater inspection of the dock was performed on May 11, 2013.

A Level II underwater inspection was performed on the timber piles and the timber mooring piles at the end of the dock. A visual inspection of the elements underwater was supplemented by the use a sounding hammer and by feel.

The underwater inspection team consisted of the team leader and underwater inspector, Aaron Immel, PE, CBI; one assistant team leader and underwater inspector, Matt Burnett, EI, CBI, and two underwater inspectors, Paul Swann, CBI and Todd Powell, CBI. Each dive consisted of two divers, one safety officer/rescue diver, and one designated person-in-charge. These responsibilities alternated between the above mentioned Volkert personnel.

The inspection of the top side and underside of the dock was also performed on May 11, 2013.

STRUCTURE SUMMARY FIRE ISLAND NATIONAL SEASHORE

Figure 1: Layout of the Dock prior to Hurricane Sandy (from Google Maps)

STRUCTURE SUMMARY FIRE ISLAND NATIONAL SEASHORE

Figure 2: Typical Section of the Dock

STRUCTURE SUMMARY FIRE ISLAND NATIONAL SEASHORE

SUMMARY OF FINDINGS

The dock was heavily damaged at the time of this inspection, and the timber piles had deterioration typical of elements in this environment. Overall, the dock is rated in critical condition due to the extensive damage to the deck and superstructure, and should remain closed to the public. A large piece of debris was partially submerged approximately 20’ west of the dock near the shoreline.

Substructure Piles The timber piles and cross bracing were found to be in poor condition overall. Problems included checking with splintering and decay up to 2” deep in the normal water zone, and Pile 24-1 was broken. The pile deficiencies are listed below in Table 1 and illustrated in the Appendix.

Table 1: Pile Deficiencies

Pile No. Deficiency/Comment Photo No.

4-1 Decay up to 3-½” wide through north and south faces beginning at top of pile, extending down 2.3’. #7

5-1 Exterior decay up to 3” deep in east face beginning 1’ below top of pile, extending down 1.6’. #8

7-1 5-½” wide x 3” deep section missing from south face beginning 0.9’ from top of pile, extending down 1.5’. #9

8-1 Exterior decay up to 2” deep in south face beginning at top of pile, extending down 1.6’.

8-2 Has 1” shell in east and west faces beginning at top of pile, extending down 2’; hollow in north and south faces. #10

9-1 Exterior decay up to 2” deep in east face, 1” deep in other faces in normal water zone.

10-1 Checking up to 4” in all faces.

11-2 Split up to 1-¼” wide in north and south faces beginning at top of pile, extending down 3.5’. #11

15-2 Exterior decay up 3” deep in north, east, and west faces beginning 6” below cap, extending down 3’

17-1 Exterior decay up to 2” deep in north face beginning at top pile, extending down 2’.

18-2 Exterior decay (6” wide x 1” deep) in east face beginning 8’ below top of pile, extending down 2.5’. 1-½” diameter hole through east and west faces, 3.3’ below top of pile.

20-2 Decay (5”wide x 5”deep) in east face beginning 3’ below top of pile, extending down 0.7’, similar decay (6” deep) in west face; two 1-½” diameter through pile.

#12

24-1 Broken (near mudline) 18’ below top of pile #13

STRUCTURE SUMMARY FIRE ISLAND NATIONAL SEASHORE

Cross Bracing All of the ends of the timber cross bracing had minor to moderate decay in the normal water zone. Also, the connection hardware had up to severe rusting, many of the nuts could be destroyed with the sounding hammer. Specific issues with the bracing include:

• Both braces have been displaced from Bent #7

• South cross brace at Bent #15 was loose

• South cross brace has severe decay at Bent #19

• Lower end of north cross brace not connected at Bent #19

Bent Caps Timber bent caps, which support the timber stringers, were through bolted to each side of the piles. The caps had minor to moderate deterioration at the ends. Several had minor splitting in the areas where the deck and stringers had been removed. In addition, the connection hardware had up to severe rusting; many of the nuts could be destroyed with the sounding hammer.

Deck and Superstructure The deck and stringers sustained heavy damage during the storm. Specific issues with the deck and superstructure include:

• Spans #1 through #17 completely missing

• Spans #18 through #23 are misaligned with moderate damage

• Span #24 through #29 completely missing

Heavy amounts of debris had accumulated on the deck in the spans at the north end.

Many of the stringer spacing blocks that rest on the caps are missing or misaligned. The timber railing is misaligned, broken, and loose throughout the dock. The utility conduits that ran along both sides of the deck were severely damaged or missing.

Approach From the aerial photography and this inspection, at one time a timber boardwalk was connected to the dock. This boardwalk had sustained heavy fire damage and only remnants of the bents remained. The remaining bents near the shoreline had severe decay, and those further inland had severe fire damage.

CONCLUSIONS

Based upon the findings of this inspection, it may be more cost effective to replace the structure due to the extensive scope of work to repair the dock. The mooring pile clusters off the east side of Spans #27 through #29 could be salvaged if the dock is to remain in its current footprint. It is recommended that the dock remain closed.

Using a unit cost of $50 per square foot, the estimated cost of replacement is $130,000.

This cost does not include demolition, mobilization, or design/construction engineering.

This estimate is approximate and should be used only for preliminary planning purposes, and should not be considered a complete or final engineers estimate.

STRUCTURE SUMMARY FIRE ISLAND NATIONAL SEASHORE

TIDE TABLES

STRUCTURE SUMMARY FIRE ISLAND NATIONAL SEASHORE

REFERENCES

1. ASCE Manuals and Reports on Engineering Practice No. 101: Underwater Investigations Standard Practice Manual, American Society of Civil Engineers, 2001.

APPENDIX

PHOTOGRAPHS

PROFILE AND LAYOUT DRAWINGS

SUPPLEMENTAL DRAWINGS

PHOTOGRAPHS

PHOTOGRAPHS FIRE ISLAND NATIONAL SEASHORE

PHOTO #1: LOOKING NORTH TOWARD ISLIP

PHOTO #2: EAST SIDE

PHOTO #3: GENERAL TOP SIDE VIEW LOOKING NORTH

PHOTO #4: GENERAL UNDERSIDE VIEW OF SPAN #18 LOOKING NORTH

PHOTO #5: GENERAL VIEW OF BENT #2

PHOTO #6: GENERAL VIEW OF BENT #33

PHOTO #7: DETERIORATION OF PILE 4-1

PHOTO #8: DETERIORATION OF PILE 5-1

PHOTO #9: DETERIORATION OF PILE 7-1

PHOTO #10: DETERIORATION OF PILE 8-2

PHOTO #11: DETERIORATION OF PILE 11-2

PHOTO #12: DETERIORATION OF PILE 20-2

PHOTO #13: PILE 24-1 BROKEN NEAR MUDLINE

PHOTO #14: TYPICAL CONDITION OF CONNECTION HARDWARE FOR BENT CAPS AND CROSS BRACING, BENT #2 CAP SHOWN

PHOTO #15: DISPLACED CROSS BRACING AT BENT #7

PHOTO #16: LOOSE CONNECTION FOR SOUTH CROSS BRACE AT BENT #15

PHOTO #17: DECAY OF SOUTH CROSS BRACE AT BENT #19

PHOTO #18: GENERAL TOP SIDE VIEW LOOKING NORTH FROM BENT #17

PHOTO #19: TYPICAL CONDITION OF DECK

PHOTO #20: DAMAGE TO DECK AND STRINGERS IN SPANS #22 AND #23

PHOTO #21: DAMAGE TO DECK AND STRINGERS IN SPANS #24 AND #25

PHOTO #22: DEBRS ON DECK IN SPANS #25 AND #26

PHOTO #23: DAMAGE TO DECK AND STRINGERS IN SPANS #28 THROUGH #30

PHOTO #24: TYPICAL DAMAGE TO RAIL POSTS

PHOTO #25:MISALIGNMENT OF EAST RAIL IN SPANS #17 THROUGH #22

PHOTO #26: DAMAGE TO UTILITIES ALONG EAST SIDE NEAR SPAN #18

PHOTO #27: GENERAL VIEW OF BOARDWALK BENTS LOOKING SOUTH

PHOTO #28: TYPICAL CONDITION OF BURNT BOARDWALK BENTS

PHOTO #29: TYPICAL DETERIORATION OF BOARDWALK BENTS

PHOTO #30: GENERAL VIEW OF MOORING PILE CLUSTERS OFF OF SPANS #27 THROUGH #29

PROFILE AND LAYOUT DRAWINGS

Fire Island Lighthouse Dock Fire Island National Seashore May 11, 2013

Profile Measuerments

Groundline measurements taken from Top of Cap

Top of Water measurement: Left: 2.8, Right: 2.8' at Bent 2 at 09:00 EDT.

Measurement (ft) Bent No. Left Right

1 3.9 2.9 2 4.3 4.3 3 4.3 4.4 4 4.9 4.7 5 5.0 5.1 6 5.8 5.5 7 6.2 5.8 8 6.5 6.2 9 7.1 6.8

10 7.3 7.2 11 7.4 7.5

12 7.7 7.7

13 7.9 8.2

14 8.8 8.5

15 9.1 8.9

16 9.5 9.3

17 9.7 9.5 18 9.1 9.0 19 8.8 8.8 20 8.8 8.8 21 12.7 12.5 22 11.7 11.5 23 13.7 13.5 24 13.7 13.9 25 13.6 15.0

26 13.6 14.4

27 14.0 13.9

27B 15.4 13.9

28 14.0 13.9

29 14.0 12.6

30 12.4 10.4

31 12.4 10.4

32 10.1 10.1

33 10.1 10.1

-10

-10

ELEVATION

PLAN

B E

N T

B E

N T

B E

N T

.0

.6

AT FIRE ISLAND NATIONAL SEASHORE

FIRE ISLAND LIGHTHOUSE DOCK

NOTES:

GROUND LINE

EXISTING

8.8’

10.6’10.6’

2.7’2.0’1.7’

\ TO 13"\ PILE SIZES VARY FROM 10"3.

ELEVATIONS ASSUMED BASED ON MEAN SEA LEVEL.2.

FIELD MEASUREMENTS FROM 2013 BRIDGE INSPECTION.1.

228.1’

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

262728

MISSING DECK AND RAILS SPANS #1 TO #16

MISALIGNED SPANS #17 TO #22

REMAINING DECK & RAILS

B E

N T

B E

N T

BENT #26

BENT #27B

(TYP.)

CLUSTERS

MOORING

SUPPLEMENTAL DRAWINGS

5� "

AT FIRE ISLAND NATIONAL SEASHORE

FIRE ISLAND LIGHTHOUSE DOCK

NOTE:

\ TO 13"\ PILE SIZES VARY FROM 10"

SECTION A-A

N

SECTION C-C

PILE 4-1 PILE 7-1

PILE

TOP OF

AA

3� "

SECTION B-B

B B

WATER ZONE

DECAY IN

TYPICAL EXT.

DECAY

2" EXT.

N

PILE

TOP OF

C C

DECAY

AT FIRE ISLAND NATIONAL SEASHORE

FIRE ISLAND LIGHTHOUSE DOCK

PILE 8-1

SECTION D-D

DECAY

3"

D D

PILE 8-2

SECTION E-E

EE

1" SHELL

DECAY

NOTE:

\ TO 13"\ PILE SIZES VARY FROM 10"

PILE

TOP OF

PILE

TOP OF

N N

PILE 11-2

SECTION F-F

F F

SPLIT

1� "

UP TO

AT FIRE ISLAND NATIONAL SEASHORE

FIRE ISLAND LIGHTHOUSE DOCK

SECTION G-G

NOTE:

\ TO 13"\ PILE SIZES VARY FROM 10"

5"

DECAY

G G

PILE 20-2

N N

PILE

TOP OF

PILE

TOP OF