DR Inspection Report - ElCap DockRepairs - Remote Dock 2021-09-29.pdf

United States Department of Agriculture Remote Dock and Marine Facility Inspections

Southeast Alaska/Tongass National Forest

MATOC Agreement No. 1205G219D005 Task Order No. 12010920F0013

Inspection of El Capitan Remote Dock Prince of Wales Island|Thorne Bay Ranger District

Inspection October 10, 2020

United States Department of Agriculture

Remote Dock and Marine Facility Inspections Southeast Alaska/Tongass National Forest

Contract No. 12010920F0013

Inspection of El Capitan Remote Dock Prince of Wales Island | Thorne Bay Ranger District

Inspected: October 10, 2020

Report Date: September 29, 2021

Joshua Steiner, PE Inspection Leader CONSOR Engineers, LLC

Heath Pope, PE Vice President CONSOR Engineers, LLC

El Capitan Remote Dock Inspected October 10, 2020

TABLE OF CONTENTS

1 Scope of Work and Inspection Procedure

2 Definitions, Rating Criteria, and Terminology

3 Facility Description

4 Inspection Findings

4.1 General Inspection Findings

4.2 Cathodic Protection System

4.3 Abutment

4.4 Pin and Hanger System

4.5 Gangway

4.6 Guide Piles

4.7 Pile Guides

4.8 Floating Docks

4.9 Safety Ladder

4.10 Log Fender Camel

5 Repair Recommendations

Appendix A Damage Rating Criteria ..................................................................................................... A-1

Appendix B Facility Sketches ................................................................................................................. B-1

Appendix C Photos ................................................................................................................................ C-1

1 SCOPE OF WORK AND INSPECTION PROCEDURE

In October 2020, CONSOR Engineers, LLC performed inspections of 16 Forest Service dock facilities in

Southeast Alaska. These inspections were performed with the assistance of Mott MacDonald and R&M

Engineering for SCJ Alliance, under contract to the United States Department of Agriculture (USDA).

The purpose of these inspections was to document and assess the dock facility's existing condition, develop rehabilitation/repair recommendations, and provide the documented field information for the future rehabilitation/repair engineering design and contractor bidding phases. The services performed included a Repair Design Inspection of the accessible underwater and above water structural elements composing the facilities and preparation of inspection reports summarizing the findings and repair recommendations. All inspections were performed in accordance with ASCE MOP 130: Waterfront

Facilities Inspection and Assessment.

The dock facilities were inspected by a crew of five inspectors, led by a Professional Engineer familiar with inspection of waterfront facilities. The docks were accessed by boat, and the above water inspection was performed using various hand tools, measuring devices, and cameras. The underwater inspection was performed using tethered SCUBA with hardwire communications equipment, using various hand tools, an ultrasonic thickness measuring gauge, bathycorrometer, and cameras.

2 DEFINITIONS, RATING CRITERIA, AND TERMINOLOGY

The conditions of the dock facility and structural systems are rated in accordance with MOP 130 according to the Condition Assessment Rating below. Additionally, the inspected structural elements are assigned damage ratings from Minor to Severe, shown in Appendix A.

CONDITION ASSESSMENT RATINGS

6 – Good No visible damage or only minor damage noted. Structural elements may show very minor deterioration, but no overstressing observed. No repairs are required.

5 – Satisfactory Limited minor to moderate defects or deterioration observed but no overstressing observed. No repairs are required.

4 – Fair All primary structural elements are sound but minor to moderate defects or deterioration observed. Localized areas of moderate to advanced deterioration may be present but do not significantly reduce the load-bearing capacity of the structure.

Repairs are recommended, but the priority of the recommended repairs is low.

3 – Poor Advanced deterioration or overstressing observed on widespread portions of the structure but does not significantly reduce the load-bearing capacity of the structure.

Repairs may need to be carried out with moderate urgency.

2 – Serious Advanced deterioration, overstressing, or breakage may have significantly affected the load-bearing capacity of primary structural components. Local failures are possible and loading restrictions may be necessary. Repairs may need to be carried out on a high-priority basis with urgency.

1 – Critical Very advanced deterioration, overstressing, or breakage has resulted in localized failure(s) of primary structural components. More widespread failures are possible or likely to occur, and load restrictions should be implemented as necessary. Repairs may need to be carried out on a very high-priority basis with strong urgency.

3 FACILITY DESCRIPTION

The facility at El Capitan includes a landside abutment supporting the gangway, gangway, a floating main dock, a floating finger dock, and a log fender camel. The floating docks are timber frames with plastic coated foam floatation secured by two steel pipe guide piles each. The perimeters of the docks have timber curbs on composite chocks, with no mooring hardware. The log fender camel straddles three steel pipe guide piles that are separate from the dock, with two logs on the offshore side and one log on the inshore side. The logs are connected with timber boards and lag bolts. The general layout of the facility is shown below.

Figure 1: General Layout

Access to the dock is provided by a steel gangway that is 65 ft long and 64 in. wide with a 39 in. high handrail with top and bottom transition plates. The walking surface varies: the left 28 in. is constructed of metal grating with L4x4 treads spaced at 16 in. on center and the right 36 in. is constructed of three 11.25

in. wide timber planks with plastic netting nailed to the top as a tread surface. The gangway is connected to the landside abutment by pin and hanger assemblies and supported by the dock with a skid-style landing consisting of steel L shapes. The abutment is a timber abutment constructed of 12 in. x 12 in.

timbers.

The water depths at the site vary from 3.9 ft to 11.8 ft relative to Mean Lower Low Water and are referenced to Tide Station 9450460 Ketchikan, AK.

This facility is typically used by recreational boaters for pedestrian access to the shore. There were no boats present at the time of inspection; typical boats are likely shorter than 30 ft overall length, although larger boats were observed at some of the other inspected facilities. There was one Forest Service barge with two temporary floating docks that was moored to the guide piles for the log fender camel at the time of inspection.

Drawings and photos are presented in Appendix B: Facility Sketches and Appendix C: Photos, respectively.

4 INSPECTION FINDINGS

4.1 GENERAL INSPECTION FINDINGS

Overall, the facility is in poor condition, primarily due to the serious condition of the finger dock and critical condition of the abutment. Detailed inspection findings for the individual structural components are presented below.

4.2 CATHODIC PROTECTION SYSTEM

There was no cathodic protection system observed at the site. Pile thickness and cathodic potential measurements are presented in Section 4.6 Guide Piles.

4.3 ABUTMENT

The timber abutment is in critical condition. The abutment timbers are severely decayed, resulting in partial loss of anchorage of the steel straps that support the gangway. Additionally, the abutment has rotated 20 degrees offshore, resulting in the gangway contacting the riprap below. It could not be determined in the field whether the abutment was pile supported.

4.4 PIN AND HANGER SYSTEM

The pin and hanger system is in critical condition due to partial loss of anchorage of the hangers to the abutment. The left anchor strap has partially pulled out of the abutment, the right strap has a loose lag bolt and both straps have reduced embedment for all lag bolts due to the interior decay of the abutment timber.

4.5 GANGWAY

The gangway, including the top and bottom transition plates, is in fair condition. There are two loose bolts at the inshore transition plate and the gangway is impacting the riprap at the abutment. There is one loose intermediate rail at the abutment and there is more than 4 in. of clear space between intermediate rails.

There is no ultra-high molecular weight plastic (UHMW) material on the gangway landing skid plates.

4.6 GUIDE PILES

The guide piles are in fair condition. Pile 2 has major section loss due to corrosion at the mudline, and all piles typically exhibit minor to moderate corrosion and pitting within the bottom 8 ft. The piles are not capped. Piles 1 and 3 were filled with water and Piles 2, 4, 5, 6, and 7 have grass growing out of the tops.

Steel pile wall thickness measurements are provided in the table below (10% of piles were required to be measured).

Table 1: Pile Section Loss

Pile ø

(in.)

Material

Steel Thickness (in.) Section Loss (in.2)

Original Waterline Mid-height Mudline

Original Area

Remaining Area

% Section Loss

1 16.2 Steel 0.375 - - - - - -

2 16.2 Steel 0.375 0.376 0.378 0.264 18.643 13.033 30.1%

3 12.9 Steel 0.380 - - - - - -

4 12.9 Steel 0.380 0.382 0.360 0.348 14.946 13.653 8.7%

5 16.2 Steel 0.375 - - - - - -

6 16.2 Steel 0.375 - - - - - -

7 16.2 Steel 0.375 - - - - - -

The cathodic potential readings were normal for bare carbon steel in seawater without cathodic protection. Cathodic potential readings are presented in the table below (10% of piles were required to be measured).

Table 2: Cathodic Potential Readings

Pile ø (in.) Material Cathodic Potential Readings (mV)

Waterline Midheight Mudline Average

1 16.2 Steel - - - -

2 16.2 Steel -663 -677 -676 -672

3 12.9 Steel - - - -

4 12.9 Steel -707 -707 -707 -707

5-7 12.9 Steel - - - -

4.7 PILE GUIDES

The pile guides are in satisfactory condition with no deficiencies at the time of inspection. There is no substantial wear on the steel guides or UHMW guide material.

4.8 FLOATING DOCKS

The docks are in poor condition due to overstressing of the frame and uneven float distribution on the finger dock.

The transition plate between the main dock and finger dock consists of a diamond plate steel sheet. The plate is connected to the main dock with four bolts and one of the bolts is loose.

4.8.1 Floating Main Dock

FLOATS

The float material is plastic encased foam. The floats are randomly located throughout and cover approximately 75% of the main dock footprint. The freeboard of the main dock varies from 5.5 in. to 12 in.

FRAMING

The timber framing system had no deficiencies at the time of inspection. The construction of the framing system is shown in the drawings in Appendix B.

DECKING

The decking consists of 11.5 in. x 1.5 in. planks and is typically in satisfactory condition with random loose nails and vegetation and algae growth concentrated around the corners and edges of the deck. There are three abandoned U-bolts protruding from the deck on the left side of the gangway landing that present a tripping hazard. The deck is typically very slick and is a slipping hazard.

CURB

The curb consists of 5.5 in. x 5.5 in. timbers supported on a stack of four 1 in. x 5 in. x 12 in. composite chocks spaced at 6 ft on center. The curbs have one 2 ft long split and one 3 ft long shake.

MOORING HARDWARE

There is no mooring hardware at this dock.

FENDER SYSTEM

There is no fender system at this dock.

4.8.2 Floating Finger Dock

FLOATS

The float material is plastic encased foam. The floats in the middle portion of the structure are in place;

however, there are dislodged and missing floats near both ends. The freeboard of the finger dock varies from 6 in. to 13.5 in. and is typically lower at both ends, creating a camber along the dock.

FRAMING

The timber framing system is in serious condition, with noticeable camber along its length, indicating overstressing of the longitudinal timber members. The construction of the framing system is shown in the drawings in Appendix B.

DECKING

The decking consists of 11.5 in. x 1.5 in. planks and is typically in fair condition with vegetation and algae growth throughout. The deck is typically very slick and is a slipping hazard.

CURB

The curb consists of 3.5 in. x 3.5 in. timbers supported on a stack of three 1 in. x 3.5 in. x 12 in. composite chocks. The curbs are typically in satisfactory condition. The offshore curb connection at the middle of the dock is misaligned up to 1 in. due to the camber of the dock.

MOORING HARDWARE

There is no mooring hardware at this dock.

FENDER SYSTEM

The fender system consists of tires spaced approximately 4 ft on center.

4.9 SAFETY LADDER

There is no safety ladder present at the site.

4.10 LOG FENDER CAMEL

The log fender camel is in serious condition. The three logs that compose the camel do not have sufficient buoyancy due to deterioration and saturation.

5 REPAIR RECOMMENDATIONS

The following table summarizes the repair recommendations for this facility.

Table 3: Repair Recommendations

Structure Element Location Quantity Defect Repair Priority Comments

Abutment Abutment Above Water 1 EA Severe decay and rotation of timber abutment with partial loss of gangway anchorage

Reconstruct decayed and unstable abutment. Reattach Pin and Hanger system

1-High Structural /safety– Restore structural capacity and mitigate failure hazard

Dock Safety Ladder Above Water 1 EA No safety ladder present Install safety ladder 1-High Safety - Provide safe emergency egress from water

Finger Dock Floating Finger Dock

Waterline 1 EA Overstressing of timber frame and uneven float module distribution

Remove and replace dock with new dock (include non-slip composite decking, curbs, and mooring hardware).

1-High Structural – Restore structural capacity

Gangway Landing Skids Above Water 25 LF Missing UHMW Install UHMW material at gangway landing

1-High Structural – Prevent further deterioration

Gangway Pin and Hanger

Above Water 2 EA No redundant gangway support system Install redundant safety system 1-High Safety – Provide a redundant anchorage point for the gangway

Gangway Framing/ Riprap Clearance

Above Water 2 CY Riprap impacts gangway framing at low tide

Remove riprap under gangway to provide sufficient clearance.

1-High Structural – Prevent impact damage from riprap

Main Dock Floatation Modules

Underwater 1 LS Insufficient floatation resulting in uneven freeboard

Replace deteriorated and loose foam floatation to provide at least 12 in.

freeboard on both docks

1-High Structural – Prevent further deterioration

Main Dock Steel Pipe Guide Pile

Underwater 1 Pile Major corrosion with section loss up to 30%

Replace Pile 2 with new pile 1-High Structural – Restore structural capacity

Main Dock Fender System

Waterline 100 LF No fender system Install rubber D fender system along left, right, and offshore faces.

2-Med Convenience/Safety - Provide safe mooring and berthing

Main Dock Mooring Hardware

Above Water 16 EA No mooring hardware Install sixteen 12 in. cleats. 2-Med Convenience – Provide secure mooring

Main Dock Decking Above Water 1100 SF Slick decking with isolated loose nails and vegetation/algae growth.

Remove timber decking and replace with non-slip composite decking

2-Med Structural/Safety– Reduce deterioration rate and mitigate slip hazard

Main/Finger Docks

Pile Corrosion Protection

Below Water 7 Piles No corrosion protection system Provide sacrificial anode cathodic protection system

2-Med Estimated min. mudline depth 6.6 ft (main dock),

7.4 ft (finger dock)

Main/Finger Docks

Steel Pipe Guide Piles

Above Water 7 Piles Piles with no caps and filled with water/vegetation

Remove water and vegetation from pile tops and provide caps

2-Med Structural – Reduce deterioration rate

Gangway Top Transition Plate

Above Water 2 EA Two loose bolts at inshore transition plate

Replace two loose bolts 3-Low Safety - Mitigate trip hazard

Log Fender Camel

Log Fender Camel

Waterline 1 EA Insufficient buoyancy and heavy deterioration of camel

Remove and replace log fender camel with composite camel.

3-Low Convenience - Provide safe mooring

Main Dock Curb Above Water 100 LF One 2 ft long split and one 3 ft long shake

Remove 6x6 timber curb and replace with 6x6 composite curb

3-Low Structural – Reduce deterioration rate

Main/Finger Docks

Dock Transition Plate

Above Water 1 EA Loose bolt at dock transition plate Replace loose connection bolt 3-Low Safety - Mitigate fall hazard

Gangway Handrails Above Water 650 LF Moderately weathered and one loose intermediate rail. Rails do not meet IBC/ADA Standards

Remove existing intermediate rails and install new intermediate rails to provide a maximum clear spacing of 4 in. Install new top rails for a top rail height of 42 in.

4-Option Safety – Mitigate fall hazard

A-1

Appendix A Damage Rating Criteria

A-2

Source: ASCE MOP 130 Waterfront Facilities Inspection and Assessment.

A-3

A-4

A-5

A-6

A-7

Source: POLATRAK CP Gun Operation Manual

B-1

Appendix B Facility Sketches

Dock: El Capitan Island: Prince of Wales Ranger District: Thorne Bay Inspection Date: October 10, 2020

UNITED STATES DEPARTMENT OF AGRICULTURE

REMOTE DOCK AND MARINE FACILITY INSPECTIONS

Southeast Alaska/Tongass National Forest Contract No. 12010920F0013

SHORELINE

(VARIES)

MAIN DOCK

FINGER DOCK

11.5"x1.5" DECK

PLANKS (TYP)

3.5"x3.5" TIMBER CURB

5.5"x5.5" TIMBER CURB

16.2" Ø x 0.375" W.T.

STL PIPE PILE (TYP)

DWG 1 General Layout (SCALE: NTS)

X" X'

7.5" 7.3'

6.5" 8.4'

12.0" 8.2'

9.0" 10.6'

10.0" 6.9'

8.3" 11.8'

Water depth is presented relative to MLLW based on Tide Station 9450460Ketchikan, AK

TIMBER GANGWAY ABUTMENT

STEEL

GANGWAY

12.9" Ø x 0.375" W.T. STL PIPE PILE (TYP)

5.5" 11.1'

12" TIMBER PLANKS WITH

PLASTIC NETTING TREAD

STEEL GRATE

WITH L4X4

TREADS

A

B

40'

40'

15'

36'

30'-6" 16'-1"

12'

L3x2x3/8 GANGWAY SKID

30'-3"

8'-5"

PILE 1

PILE 2

PILE 3

PILE 4

PILE 5

PILE 6

PILE 7

16.2" Ø x 0.375" W.T.

STL PIPE PILE (TYP)

20'

TIMBER FENDER CAMEL

12.0" 6.6'

7.8" 3.9'

8.3" 4.1'

10.5" 6.6'

6.0" 7.4'

10.0" 7.7'

13.5" 9.0'

FREEBOARD (INCHES)

DEPTH (FEET)

TIRE FENDER (TYP)

UNITED STATES DEPARTMENT OF AGRICULTURE

REMOTE DOCK AND MARINE FACILITY INSPECTIONS

Southeast Alaska/Tongass National Forest Contract No. 12010920F0013

11.5"x1.5" DECK

PLANKS (TYP)

DWG 2 Cross Sections

3' O.C. (TYP) 3"x8" TIMBER

STRINGER (TYP)

1.5"x9" TIMBER WALE (TYP)

INTERMITTENT

STYROFOAM FLOAT FROM

DECK BOARDS DOWN

5.5"x5.5" TIMBER CURB (TYP)

3.5"x8" TIMBER

STRINGER (TYP)

3.5"x3.5" TIMBER CURB (TYP)

1.5"x11.5" TIMBER WALE (TYP)

11.5"x1.5" DECK PLANKS (TYP)

8'-5"

20"x10.5" STYROFOAM FLOAT (TYP)

[2] 7.5"x1.5" TIMBER CROSS

BEAM @ 3' O.C. (TYP)

12"x12" TIMBER

8.0"

2.50"

5.5"

0.75" THICK

STEEL HANGER

1" Ø BOLT (TYP)

SOIL

FOUR 1"x5"x12" COMPOSITE

CHOCK @ 72" O.C. (TYP)

36' (TYP)

1.5"x8" TIMBER WALE (TYP)

4"x10" TIMBER @ 7" O.C.

3'-6" O.C. (TYP)

THREE 1"x3.5"x12" COMPOSITE CHOCKS (TYP)

2" 2"

20°

Dock: El Capitan Island: Prince of Wales Ranger District: Thorne Bay Inspection Date: October 10, 2020

ABUTMENT ELEVATION

0 1/2' 1'

SCALE: 1"=1'-0" OFFSHORE INSHORE

FINGER DOCK CROSS SECTION

0 2' 4'

SCALE: 1/4"=1'-0" OFFSHORE INSHORE

MAIN DOCK CROSS SECTION

OFFSHORE INSHORESCALE: 3/16"=1'-0"

0' 1' 2' 4' 6'

TIRE FENDER (TYP)

ABUTMENT SUPPORT COULD NOT

BE DETERMINED IN THE FIELD

UNITED STATES DEPARTMENT OF AGRICULTURE

REMOTE DOCK AND MARINE FACILITY INSPECTIONS

Southeast Alaska/Tongass National Forest Contract No. 12010920F0013

DWG 3

3'x1" SHAKE

IN CURB

TYPICAL DEFICIENCIES

1. Inadequate floatation - Freeboard is not uniform across floats.

2. Timber decking is deteriorated with vegetation and algae growth.

3. Main dock deck planks typically have protruding nails.

4. Intermediate gangway rails have greater than 4 in.

of clear space between rails.

5. All piles are missing caps and are filled with water/vegetation.

6. All piles have minor to moderate corrosion on the bottom 8 ft.

NO UMHW INSTALLED

ON GANGWAY SKIDS

GANGWAY IMPACTING RIPRAP

DECAYED AND UNSTABLE ABUTMENT

LOOSE AND DETACHED PIN AND

HANGER PLATES

ABANDONED U-BOLTS

LOOSE TRANSITION

PLATE CONNECTIONS

DISLODGED AND

MISSING FLOTATION

LOOSE TRANSITION

PLATE BOLT

DISCONNECTED RAILING BOARD

2' LONG SPLIT IN CURB

FRACTURE

CRITICAL PIN

AND HANGER

WITH NO

REDUNDANT

SYSTEM

NOTE: The three piles and log boom fender located to the East of the dock should be removed (not shown)

MAJOR PILE SECTION LOSS

DUE TO CORROSION

OVERSTRESSING IN

DOCK TIMBERS DUE

TO CAMBER

Dock: El Capitan Island: Prince of Wales Ranger District: Thorne Bay Inspection Date: October 10, 2020

Deficiency Plan

C-1

Appendix C Photos

C-2

Photo 1: General view of the facility.

Photo 2: General view of the abutment and gangway.

C-3

Photo 3: General view of the pin and hanger assembly.

Photo 4: Abutment deterioration, note 20o rotation.

C-4

Photo 5: Partially detached hanger connection.

Photo 6: Gangway impact on riprap.

C-5

Photo 7: Loose inshore transition plate bolts.

Photo 8: Detached gangway rail. Note inadequate railing spacing.

C-6

Photo 9: General view of the main dock. Note water and vegetation in piles.

Photo 10: Typical condition of main dock timber above water.

C-7

Photo 11: Typical condition of main dock timber below water.

Photo 12: Typical pile guide. Note the vegetation growth on the deck.

C-8

Photo 13: View of the gangway landing.

Photo 14: Abandoned U bolts on left side of gangway landing.

C-9

Photo 15: Split in timber curb.

Photo 16: General view of the finger dock. Note vegetation growth in deck.

C-10

Photo 17: Loose connection in transition plate between docks.

Photo 18: View of the finger dock. Note significant camber

C-11

Photo 19: Misaligned timber curb due to camber at center of finger dock.

Photo 20: Submerged log fender camel.

C-12

Photo 21: Major section loss due to corrosion within the bottom 8 ft of Pile 2.