Rock_Harbor_Dock_Report_FINAL.pdf

Rock Harbor Ferry Dock Inspection Report Isle Royale, Michigan

Submitted to:

Mr. Bob Pray Marine Services Corp.

70 Fargo Street Boston, Massachusetts 02210

Submitted by:

GEI Consultants of Michigan, P.C.

109 W. Baraga Street Marquette, Michigan 49855

September 23, 2016

GEI Project No. 1610430

George M. Meister, P.E.

Senior Project Engineer

Michael D. Carpenter, P.E.

Senior Project Engineer

Project #1610430 September 23, 2016

Table of Contents

1. Introduction

1.1 Background

1.2 Project Description

1.3 Purpose

2. Field Inspections

2.1 Substructure Inspection

2.2 Level I – Visual & Tactile Inspection

2.3 Level II – Up-Close & Detailed Inspection

2.4 Superstructure Inspection

2.5 Lake Bottom

3. Inspection Findings

3.1 Below Water

3.2 Above Water

3.3 Lake Bottom

Figures

Figure 1: Typical Crib Structure (in text) Figure 2: Plan and Elevation of Dock Figure 3: Map of Notable Areas Figure 4: Rock Harbor Dock Soundings

Appendices

Appendix A: Photo Log

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GEI Consultants of Michigan, P.C. i

Project #1610430 September 23, 2016

1. Introduction

1.1 Background

The Rock Harbor Ferry Dock on Isle Royale provides access to National Park Service (NPS) employees and visitors via ferry and seaplane. The dock is 210 feet long by 31 feet wide and can become congested from visitors and cargo loading and offloading. The largest ship currently using the dock is the Ranger III operated by the NPS out of Houghton, Michigan. The draft of the Ranger III brings the hull of the ship to, or near, the lake bottom at the dock. Dredging has been performed in the past to accommodate the draft of the Ranger III. Widening of the dock has been proposed to provide the following benefits:

1. Additional dock platform space would relieve congestion around the ferry’s cargo operations area and improve safety of departing and/or boarding passengers.

2. The dock platform would be extended toward the deeper water.

1.2 Project Description

The Rock Harbor ferry dock consists of a five stone-filled timber crib structures with a concrete cap with approximate plan dimensions of 30 feet by 40 feet. The crib structures are framed with 12-inch by 12-inch, 8-foot by 12-foot timbers and 2-inch by 12-inch timber sheathing. The base and top of the crib structures have multiple rows of longitudinal 12-inch by 12-inch timbers stacked atop each other. The framing between the base and top alternates from longitudinal to transverse pieces and are secured by 7/8-inch diameter bolts with washers.

There is a 30-inch tall by ¼-inch thick steel plate at the water line on the east, west and south sides secured to the dock with lag bolts. The plate is presumably in place for ice protection.

The crib structures are capped by an 8-inch concrete cap bordered by 8-inch by 8-inch timbers. A sketch of the typically observed construction of one of the crib structures is included in Figure 1 above. The bottom of the south side of the dock appears to have had approximately two feet deep of 4-inch to 12-inch stone placed for scour protection. The north side of the dock has an additional walkway supported by metal

Figure 1 – Typical Crib Structure

GEI Consultants of Michigan, P.C. 1

Project #1610430 September 23, 2016 brackets just above the water line for access to small boats. A rendering of typical crib structure is shown in Figure 2.

1.3 Purpose

Widening of the dock has been proposed in order to reduce the congestion in the cargo operations area and increase the safety of the ferry passengers. GEI Consultants of Michigan, P.C. (GEI) has been retained to evaluate the current condition of the dock and provide depth soundings near the dock. The purposes of this assessment were to:

• Conduct a visual inspection of the wood cribbing, concrete deck and steel elements of the dock and lake bottom;

• Document the findings using photographs and video;

• Measure the current water depths 15 feet from the dock.

Photo 1 - Ranger III at dock in Rock Harbor

GEI Consultants of Michigan, P.C. 2

Project #1610430 September 23, 2016

2. Field Inspections GEI mobilized to the Rock Harbor ferry dock on Isle Royale via the Ranger III on Tuesday September 6, 2016. The three person professional engineer/diver team departed the ship along with a 16-foot aluminum boat at Mott Island and then proceeded to the Rock Harbor Dock. George M. Meister, P.E. conducted the substructure inspection with assistance from Alan Pepin, P.E. Michael D. Carpenter, P.E. conducted the inspection above the water surface. Photo and video documentation was conducted on the entire dock. A photo log and a CD containing the video from the inspection are included in Appendix A. The inspection approach for both the underwater and superstructure portions of the dock are summarized in the following sections.

2.1 Substructure Inspection

The dive inspection completed by GEI included checking accessible portions of the dock for misalignment and loss of section, as well as for evidence of decay or weathering. The dive inspection was documented on a sketch of the structure during the inspection, and through the use of underwater photography and video recordings. A description of each type of dive is included in the following sections.

2.2 Level I – Visual & Tactile Inspection

Longitudinally there are 5 crib structures along the dock. Divers accessed the crib structures on both sides of the dock. A portion of the crib structures are inaccessible due to the connection to the section of the dock that runs perpendicular to shore. This provided an appropriate and representative sample of the submerged portions of the dock.

2.3 Level II – Up-Close & Detailed Inspection

Accessible crib structures were inspected and measured by cleaning marine growth and utilizing picks or awls to determine the soundness of the timber. The timber framing elements and sheathing were inspected throughout the dock. In addition, the divers assessed the condition of the bolts that connect the elements of timber cribbing.

A visual and tactile inspection was completed on the substructure of the dock beginning at the east side progressing westerly along the south side and then back along the north side to the connection with the section of the dock perpendicular to shore. The dock section that is perpendicular to the shore was not included in the scope of this inspection. The inspection included up close visual inspection of the entire dock along with timber soundness testing by knife or hammer on selected areas of the dock. Selected bolts were cleaned of corrosion and marine growth to assess condition and level of corrosion.

Photo 2 - Dive inspector testing soundness of crib timber

GEI Consultants of Michigan, P.C. 3

Project #1610430 September 23, 2016

2.4 Superstructure Inspection

The superstructure of the crib structures and concrete cap were visually inspected. The timbers were checked for soundness. Bolts and metal connections were visually inspected for corrosion. The concrete cap was visually inspected for signs of wear and deterioration such as cracking, spalling, and delamination.

2.5 Lake Bottom

The lake bottom was assessed for types of material and depth. Signs of scour were also assessed. Soundings were taken by line and weight generally at 15 and 35 foot distances from the dock. A contour map based off of the soundings is included in Figure 4.

According to the National Oceanic and Atmospheric Administration (NOAA), the water surface elevation of Lake Superior was 602.69 feet during the inspection.

GEI Consultants of Michigan, P.C. 4

GEI Consultants of Michigan, P.C. 5

Isle Royale, Michigan Project #1610430 September 23, 2016

3. Inspection Findings

Overall, the dock was in good condition and is serviceable; however, specific elements are noted in the sections below.

3.1 Below Water

The timbers were found to be sound with degradation at the ice interface area of the dock. The top of the metal plates were at the current water line, and were loosening. Some bolts were able to be removed by hand or were missing, or have worked their way loose and fallen to the lake bottom. Notable timber degradation was observed immediately below the 1/4-inch thick steel plates, which were presumably installed to protect the timbers from ice damage as shown in Photo 3. Timbers were otherwise sound and did not show signs of rot. The 7/8-inch bolts securing the crib structures together appeared to be in good shape with minimal section loss due to corrosion. The sheathing within the crib structures was in good condition.

3.2 Above Water

The concrete cap shown in Photo 4 was in good condition with only minor spalling and cracking visible. The cement had been worn from much of the surface exposing the aggregate on the cap (less than 1 inch) and steel reinforcement was not visible.

The timber was in good condition and sound with minimal degradation or rot.

3.3 Lake Bottom

The lake bottom consists of a fine to medium sand with some cobbles. Stone scour protection from the dock has shifted away from the dock along the bottom. Some areas of the cribs were undermined approximately three feet under the dock and suspended approximately 8 to 18 inches; particularly the west end of the dock near the corners. Photo 5 shows typical undermining and differential elevations of crib joints. Bow thrusters from ferries using the dock appear to have shifted

Photo 5 - Crib joint misalignment and undermining of dock

Photo 3 - Timber degradation due to ice action

Photo 4 –Surface of dock

Project #1610430 September 23, 2016

GEI Consultants of Michigan, P.C. 6 some of the scour protection stone from the crib foundation leaving shallow depressions in the lake bottom where the ferries repeatedly activate the thrusters at the dock. Potentially, some of the stone material from within the cribs could have been lost due to the undermining shown in Photo 6; however, no voids were observed within the crib structures and inspectors were unable to determine if the stone fill within the cribs is contained by a base or grillage at the bottom of the crib structures. Referring to the cribs by number from west to east according to Figure 2, the crib structure joints between cribs 1 and 2 as well as 2 and 3 have experienced differential settlement of approximately 2 to 3 inches

Photo 6 - Typical scour protection along dock

Figures Figure 2: Plan and Elevation of Dock Figure 3: Section View Figure 4: Bathymetric Map of Soundings

GEI Consultants of Michigan, P.C.

3/16" = 1'-0"2 ELEVATION 2

3/16" = 1'-0"1 ELEVATION 1

ROCK HARBOR DOCK INSPECTION

MARINE SYSTEMS CORP.

BOSTON, MAW

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FIGURE 2

TYPICAL CRIB PLAN AND

ELEVATIONS

GEI NO. 1610430

NOTE:

SKETCHES PRESENTED IN THIS REPORT REPRESENT CONSTRUCTION

TYPICAL OF THE CRIB STRUCTURES LOCATED WITHIN THE ROCK

HARBOR DOCK. INTERNAL GEOMETRY OF THE STRUCTURE IS

ASSUMED BASED ON OBSERVATIONS MADE DURING THE INSPECTION.

LOWER

DOCK

LEVEL

ACCESS

DOCK

RAMP

RIPRAP SLOPE

WATERLINE DOCK

STRUCTURAL SLAB

SUPPORTED BY PIERS

CJ

CRIB 1

CRIB 2

CRIB 3 CRIB 4 CRIB 5

±42' TYP.

±3 1'

T Y

P

5 5

121212

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Fig. 3

Rock Harbor Dock Inspection Rock Harbor, MI Isle Royale, MI

Marine Systems Corp Boston, MA

ROCK HARBOR DOCK

MAP OF NOTABLE AREAS

Sept. 2016Project 1610430

Consultants

LEGEND:

CLEAT

BOLLARD

DRAIN

SCALE:

20 40

1" = 20'

NOTES:

1. DETERIORATION AT CORNER ON WOOD AT PLASTIC

2. STEEL PLATE AT WATERLINE ~30" WIDE AND ~1/4" THICK WITH LAG BOLTS (MANY LOOSE OR MISSING)

3. SCOUR PROTECTION STONE. APPROXIMATELY 1' TO 3' THICK AND 10' TO 15' WIDE.

4. CONSTRUCTION JOINTS ON SURFACE ARE ASSOCIATED WITH SEPARATE CRIBS

5. SMALL BOAT ACCESS LEVEL

6. EAST SIDE IS LOWER ~2" THAN WEST SIDE

7. SAME AS #6

8. UNDERMINING WEST SIDE OF JOINT (ROCK LOSS)

9. STEEL PLATE COMPLETELY LOOSE AND NEARLY FALLING OFF

10. DOCK SUSPENDED DUE TO UNDERMINING OF MATERIAL FROM DOCK

11. BOTTOM OF CRIBBING SUSPENDED FROM BOTTOM DUE TO UNDERMINING UNTIL EAST END OF SECTION

12. CONCRETE CAP, 7"-8"

13. 2ND TIMBER BELOW WATER LINE IS DETERIORATED

14. LOTS OF DEBRIS IN CORNER WHERE RIPRAP SLOPE IS LOCATED

LAKE SUPERIOR

WATER ELEVATION 602.69' ON 9/6/2016

CONTOURS BASED ON SOUNDINGS SHOWN

ROCK HARBOR DOCK

TOP OF DOCK = ±607.5'

SOUNDING LOCATION AND DEPTH

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Fig. #4

ROCK HARBOR DOCK INSPECTION

ROCK HARBOR DOCK

ISLE ROYALE, MICHIGAN

MARINE SERVICES CORP.

BOSTON, MASSACHUSETTS

ROCK HARBOR DOCK

SOUNDINGS

SEPTEMBER 2016Project 1610430

109 W. BARAGA AVENUE

MARQUETTE, MI 49855

(906)451-4021

Consultants

SOURCE:

1. PLAN BASED ON SOUNDINGS PERFORMED ON SEPTEMBER

6, 2016 AND NOAA WATER ELEVATION OF 602.69'

DRAFT

SCALE:

20 40

1" = 20'

Appendices Appendix A: Photo Log

GEI Consultants of Michigan, P.C.

Isle Royale Rock Harbor Inspection Photos Date: September 2016 GEI Project No.: 1610430 Client: Marine System Corp (MSC) i | P a g e

Photo No. 1 – Ranger III at the Dock _______________________________________________________________ 1

Photo No. 2 – Crib Section 2 Cap __________________________________________________________________ 1

Photo No. 3 – Crib Section 2 Cap __________________________________________________________________ 2

Photo No. 4 – Crib Section 3 Cap __________________________________________________________________ 2

Photo No. 5 – Crib Section 4 Cap __________________________________________________________________ 3

Photo No. 6 – Crib Section 5 Cap __________________________________________________________________ 3

Photo No. 7 – Dock Cap Crib 4 ____________________________________________________________________ 4

Photo No. 8 – 7” to 8” Concrete Cap on North Side of Dock _____________________________________________ 4

Photo No. 9 – Crib Joint Above Water Between Cribs 4 and 5 ___________________________________________ 5

Photo No. 10 – Crib Joint Above Water Between Cribs 1 and 2 __________________________________________ 5

Photo No. 11 – Differential Settlement and Undermining of Crib 2 and 3 Joint ______________________________ 6

Photo No. 12 – Differential Settlement of Crib 1 and 2 Joint ____________________________________________ 6

Photo No. 13 – Northwest Corner of Dock Looking Northeast ___________________________________________ 7

Photo No. 14 – North Face of Dock at Intersection with Riprap Slope of the Access Dock to Shore ______________ 7

Photo No. 15 – North Face of Dock; Note Walkway for Smaller Boats _____________________________________ 8

Photo No. 16 – Framing Beneath Walkway on North Side of Dock _______________________________________ 8

Photo No. 17 – Debris at North Face of Dock at the Intersection with the Dock Heading to Shore _______________ 9

Photo No. 18 – Typical 7/8” Bolt in Crib Structure ____________________________________________________ 9

Photo No. 19 – Typical Bolt Head Under Water _____________________________________________________ 10

Photo No. 20 – Typical Bolt Head Above Water _____________________________________________________ 10

Photo No. 21 – Crib Section 1 Cap ________________________________________________________________ 11

Photo No. 22 – Diver Testing Soundness of Timber with Blunt Tipped Dive Knife ___________________________ 11

Photo No. 23 – Diver Performing Close Up Inspection ________________________________________________ 12

Photo No. 24 – 8” x 8” Timber End _______________________________________________________________ 12

Photo No. 25 – 2” x 12” Sheathing _______________________________________________________________ 13

Photo No. 26 – Timber Degradation Below Water Line at Southeast Corner Due to Ice ______________________ 13

Photo No. 27 – Typical Degradation Below Metal Sheet ______________________________________________ 14

Photo No. 28 – East Face of Dock ________________________________________________________________ 14

Photo No. 29 – East End of Dock _________________________________________________________________ 15

Photo No. 30 – East End of Dock; Degradation at Ice Line _____________________________________________ 15

Photo No. 31 – East Side Dock Sheathing __________________________________________________________ 16

Photo No. 32 – Undermining of Dock at Southeast Corner _____________________________________________ 16

Photo No. 33 – Southeast Corner of Dock Showing Deterioration of Timbers Above Water Line _______________ 17

Photo No. 34 – South Face of Dock _______________________________________________________________ 17

Photo No. 35 – South Face of Dock _______________________________________________________________ 18

Photo No. 36 – South Face of Dock Base, Southeast Corner Looking West; Note Slight Undermining ___________ 18

Photo No. 37 – South Face of Dock, Southeast Corner Looking West _____________________________________ 19

Photo No. 38 – South Side Base of the Dock; Note Slight Undermining and Scour Protection __________________ 19

Photo No. 39 – South Side of Dock; Note Scour Protection Sloping Away From Dock ________________________ 20

Photo No. 40 – Undermining on South Side of Dock __________________________________________________ 20

Photo No. 41 – South Side of Dock, Southwest End Looking East ________________________________________ 21

Photo No. 42 – South Wall ______________________________________________________________________ 21

Photo No. 43 – Undermining of the Crib 1 at the South Side of the Dock __________________________________ 22

Photo No. 44 – South Face of Crib 1 ______________________________________________________________ 22

Isle Royale Rock Harbor Inspection Photos

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Photo No. 45 – Undermining of Crib 1 _____________________________________________________________ 23

Photo No. 46 – Undermining of Southwest Corner of Dock Looking Southeast _____________________________ 23

Photo No. 47 – Undermining of Southwest Corner of Dock Looking Northwest _____________________________ 24

Photo No. 48 – Metal Plates at the Southwest Corner; Note Sheet Pulling Away from Dock __________________ 24

Photo No. 49 – Undermining of Northwest Corner of Dock Looking Northeast _____________________________ 25

Photo No. 50 – West Face of Riprap Slop of Access Dock to Shore _______________________________________ 25

Photo No. 51 – West Face of Dock ________________________________________________________________ 26

Isle Royale Rock Harbor Inspection Photos

GEI Project No.: 1610430

1 | P a g e

Photo No. 1 – Ranger III at the Dock

Photo No. 2 – Crib Section 2 Cap

Isle Royale Rock Harbor Inspection Photos

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Photo No. 3 – Crib Section 2 Cap

Photo No. 4 – Crib Section 3 Cap

Isle Royale Rock Harbor Inspection Photos

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Photo No. 5 – Crib Section 4 Cap

Photo No. 6 – Crib Section 5 Cap

Isle Royale Rock Harbor Inspection Photos

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Photo No. 7 – Dock Cap Crib 4

Photo No. 8 – 7” to 8” Concrete Cap on North Side of Dock

Isle Royale Rock Harbor Inspection Photos

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Photo No. 9 – Crib Joint Above Water Between Cribs 4 and 5

Photo No. 10 – Crib Joint Above Water Between Cribs 1 and 2

Isle Royale Rock Harbor Inspection Photos

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Photo No. 11 – Differential Settlement and Undermining of Crib 2 and 3 Joint

Photo No. 12 – Differential Settlement of Crib 1 and 2 Joint

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Photo No. 13 – Northwest Corner of Dock Looking Northeast

Photo No. 14 – North Face of Dock at Intersection with Riprap Slope of the Access Dock to Shore

Isle Royale Rock Harbor Inspection Photos

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Photo No. 15 – North Face of Dock; Note Walkway for Smaller Boats

Photo No. 16 – Framing Beneath Walkway on North Side of Dock

Isle Royale Rock Harbor Inspection Photos

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Photo No. 17 – Debris at North Face of Dock at the Intersection with the Dock Heading to Shore

Photo No. 18 – Typical 7/8” Bolt in Crib Structure

Isle Royale Rock Harbor Inspection Photos

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Photo No. 19 – Typical Bolt Head Under Water

Photo No. 20 – Typical Bolt Head Above Water

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Photo No. 21 – Crib Section 1 Cap

Photo No. 22 – Diver Testing Soundness of Timber with Blunt Tipped Dive Knife

Isle Royale Rock Harbor Inspection Photos

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Photo No. 23 – Diver Performing Close Up Inspection

Photo No. 24 – 8” x 8” Timber End

Isle Royale Rock Harbor Inspection Photos

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Photo No. 25 – 2” x 12” Sheathing

Photo No. 26 – Timber Degradation Below Water Line at Southeast Corner Due to Ice

Isle Royale Rock Harbor Inspection Photos

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Photo No. 27 – Typical Degradation Below Metal Sheet

Photo No. 28 – East Face of Dock

Isle Royale Rock Harbor Inspection Photos

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Photo No. 29 – East End of Dock

Photo No. 30 – East End of Dock; Degradation at Ice Line

Isle Royale Rock Harbor Inspection Photos

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Photo No. 31 – East Side Dock Sheathing

Photo No. 32 – Undermining of Dock at Southeast Corner

Isle Royale Rock Harbor Inspection Photos

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Photo No. 33 – Southeast Corner of Dock Showing Deterioration of Timbers Above Water Line

Photo No. 34 – South Face of Dock

Isle Royale Rock Harbor Inspection Photos

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Photo No. 35 – South Face of Dock

Photo No. 36 – South Face of Dock Base, Southeast Corner Looking West; Note Slight Undermining

Isle Royale Rock Harbor Inspection Photos

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Photo No. 37 – South Face of Dock, Southeast Corner Looking West

Photo No. 38 – South Side Base of the Dock; Note Slight Undermining and Scour Protection

Isle Royale Rock Harbor Inspection Photos

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Photo No. 39 – South Side of Dock; Note Scour Protection Sloping Away From Dock

Photo No. 40 – Undermining on South Side of Dock

Isle Royale Rock Harbor Inspection Photos

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Photo No. 41 – South Side of Dock, Southwest End Looking East

Photo No. 42 – South Wall

Isle Royale Rock Harbor Inspection Photos

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Photo No. 43 – Undermining of the Crib 1 at the South Side of the Dock

Photo No. 44 – South Face of Crib 1

Isle Royale Rock Harbor Inspection Photos

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Photo No. 45 – Undermining of Crib 1

Photo No. 46 – Undermining of Southwest Corner of Dock Looking Southeast

Isle Royale Rock Harbor Inspection Photos

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Photo No. 47 – Undermining of Southwest Corner of Dock Looking Northwest

Photo No. 48 – Metal Plates at the Southwest Corner; Note Sheet Pulling Away from Dock

Isle Royale Rock Harbor Inspection Photos

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Photo No. 49 – Undermining of Northwest Corner of Dock Looking Northeast

Photo No. 50 – West Face of Riprap Slop of Access Dock to Shore

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Photo No. 51 – West Face of Dock

Appendix A - Photo Log