d.Hells_Canyon_Boat_Dock_Facility_Condition_Assessment_Report.pdf

27 May 2015

Doug Argo, PE

Holladay Engineering Co.

32 N. Main

Payette, ID 83661

Subject: Condition Assessment – Boat Dock Facility, Hells Canyon, Oregon

Conducted on 14 April 2015

BergerABAM Job No. A15.0253

Dear Mr. Argo:

This letter report summarizes our condition and structural assessment of the boat dock facility located on the Snake River in northeastern Oregon. Our report outlines the structure type, its present condition, observed deficiencies, and recommendations for rehabilitation along with the anticipated construction costs that would be associated with rehabilitation.

INTRODUCTION AND AUTHORIZATION

On 27 March 2015, Holladay Engineering Co. authorized BergerABAM to perform a condition and structural assessment of the Hells Canyon boat launch and boat dock facility located on the

Snake River in northeastern Oregon (see Figure 1). When in operation, the boat dock facility consists of a floating dock attached to a trolley that travels along guide rails on shore. However, during the inspection the floating dock was not present. Stairs supported on grade at the south side of the trolley support frame provide access to the floating dock when in operation.

Because of high river flows and flooding, the floating dock support frame has been partially buried by rock and has experienced scour around and below the primary support beams. The

Hells Canyon Creek flood that occurred in March 2012 was a significant event that dislodged rocks and debris from above the dock and deposited it on and around the dock, damaging the steel frame members and the dock.

The project involved a below‐ and above‐water condition assessment of the dock to verify its current condition and the extent of the damage. The project also included the development of a rehabilitation concept and estimate of probable construction cost.

Figure 1 – Aerial View of Site

STRUCTURAL ASSESSMENT ACTIVITIES

On 14 April 2015, BergerABAM divers performed a topside and underwater inspection of the boat dock facility located downriver from the Hells Canyon Dam. The three‐person inspection team was led by Nick Colson, PE, dive supervisor/engineer‐diver, and included Brett Ozolin, PE, assistant dive supervisor/engineer‐diver, and Matt Perry, senior construction specialist‐ diver. The inspection team accessed the boat dock facility from shore via the stairs adjacent to the facility.

The water level elevation during the inspection was approximately 1,465 feet (NGVD29 datum) according to the local station gauge. According to the topographic survey performed on the day of the dive, the water level elevation was approximately 1,468 feet (NAVD88). Because of the shallow depth of the water at the dock facility, underwater inspection was performed using a mask and snorkel. A single snorkeler in the water, assisted by a diving tender/rescue person, performed the underwater inspection. The primary goal of the underwater inspection was to verify the location of the rails below water with visual observation and using a probe to penetrate the gravel covering the rails.

The team performed the topside inspection on foot by walking the area of the dock facility to assess its above‐water conditions. The third team member measured the structure, documented framing member sizes, and noted the condition of the structure and any observed damage.

Concurrent to BergerABAM’s field activities, WH Pacific performed topographic and bathymetric survey of the site.

STRUCTURE DESCRIPTION

The dock structure was constructed in 1984 and consisted of a floating dock attached to a trolley that travels along guide rails on shore. During the inspection, the floating dock structure was not on site and only the guide rail structure and trolley were present (see Photo 1). The two guide rails are W10x22 beams that bear directly on a gravel subgrade along the shore slope.

Diagonal and transverse L3x3x5/16 angle braces connect between the W10x22 rails (see Photo

2). The tops of the W10x22 rails are anchored and welded to a vertical W10x22 cast into concrete and embedded to an unknown distance into the ground (see Photo 3).

Photo 1 – Floating Dock Support Frame

Photo 2 – Typical rail and bracing components

Photo 3 – Vertical W10x22 anchorage member

A concrete counterweight and support tower are located at the top of the steel rail and trolley system. The concrete counterweight block measures 3 feet by 3 feet by 2 feet and the counterweight tower is constructed of L2x2x3/16 steel angles (see Photo 4).

Photo 4 – Counterweight block and tower

The trolley frame is constructed of 5‐inch by 5‐inch square tube steel members and 1/4 ‐inch diameter cable bracing (see Photo 5). The trolley rolls on 8‐inch diameter wheels that bear on each rail beam’s top flange. Below each rail beam’s top flange are 6‐inch and 4‐inch diameter wheels that roll along the web and underside of the top flange (see Photo 6).

Flat bar wheel stops are welded to the upper and lower ends of the rails to prevent the trolley from travelling beyond the length of the rails.

Access stairs run along the south side of the dock frame system and are constructed of timber stringers and metal stair treads (see Photo 7). A removable guardrail is attached to the south stair stringer, but the guardrail for the lower third of the stairs has been removed.

An access elevator and guide system is located to the south of the access stairs. The elevator and guide is not in the scope of this report.

Photo 5 – Trolley

Photo 6 – Trolley wheels

Photo 7 – Dock Access Stairs (on right) and Elevator Guide

OBSERVED CONDITIONS

The dock facility (with the exception of the dock itself) appears to be in fair condition with minor damage to the steel framing members. The damage observed was primarily at the two steel framing bays nearest the river. Deformation to rail beam top flanges existed at the interior edge of both rails, near the second transverse member from the bottom of the rails. The south rail beam deformation is more severe than the north rail beam. The south rail beam deformation is approximately 6 inches along its top flange and is bent up approximately 1 inch (see Photo 8).

At the framing bay nearest the river, a diagonal brace is heavily damaged and has broken loose from the north rail (see Photo 9). The lower end of the brace is buried under rock and was not visible.

Photo 8 – Bent flange on southern rail

Photo 9 – Damaged diagonal brace broken loose from rail

Rock and debris have accumulated on and around the dock structure framing members and the rail system is now partially buried. Between the rail beams, rock and debris have accumulated on the uphill side of the transverse members as well as on some of the diagonal braces (see

Photo 10). The lower end of the south rail is underwater and buried under approximately 2 feet of rock.

Photo 10 – Debris accumulated behind transverse bracing

Figure 2 depicts the overall construction of the frame and the locations of damage.

Figure 2 – Overall Frame Construction and Damage Locations

STRUCTURE CONDITION ASSESSMENT

Based on our observations of the steel guide frame and trolley, we rate the condition of the overall structure as fair. A fair rating is assigned because primary structural elements are sound, but some minor damage to the steel framing members is present and should be repaired to restore the dock functionality. Additionally, rock and debris material deposited on and around the framing members is inducing stresses in the framing members and connections that we assume was not anticipated in the original design. It is our understanding that the Hells

Canyon Creek flood in March 2012 was the primary contributor to the accumulation of rock and debris around the frame. This accumulation behind the framing members may also be inducing additional stress on the guide rail and the vertical anchor members embedded into the top of the shore slope.

Based on WH Pacific’s topographic survey, it appears the slope of the steel dock frame is not constant along its entire length. This varying beam slope likely indicates the beams and frame are altered from their original elevation and slope. Elevations of the beam appear to deviate by a few inches above and below an approximate average slope. This beam unevenness could affect the functionality of the floating dock and trolley when traveling along the rail.

The floating dock itself is not present and was removed by the United States Forest Service

(USFS). We assume the dock is damaged beyond repair and a new floating dock must be constructed and installed to restore functionality to the system.

The access stairs along the south side of the dock frame system exhibit moderate damage and deterioration to the timber stringers, with more significant damage near the bottom of the stringers that were more exposed to moving debris from the 2012 flood, as well as changing water levels. Steel stair treads near the bottom quarter of the stair run have been damaged and displaced from their original support condition, creating an uneven and unsafe walking surface.

RECOMMENDATIONS

To restore functionality of the boat dock facility, repairs must be made to the trolley guide frame and the floating dock must be reinstalled. It appears the dock facility damage is repairable and an entirely new dock facility is not required. Because the nature of the March

2012 flood event was rare and uncharacteristic, we believe the dock facility does not require further improvements beyond making repairs to return the dock to its original state and functionality. This assumes that the dock facility was functioning adequately prior to the flood event.

We recommend removing rock and debris that has accumulated on and around the dock frame.

The steel frame should be returned to its approximate original slope by excavating under high points in the frame and replacing the scoured and missing gravel material below the dock guide rails. Returning the frame to its original slope and straightness may require jacking the frame up in some places by a few inches. Prior to commencing any in‐water work, a sediment curtain to contain construction debris should be installed.

APPENDIX A – OPINION OF PROBABLE CONSTRUCTION COST

PROJECT: BergerABAM Job No.: PAGE:

A15.0253.00

OPERATION: ESTIMATOR: DATE:

TAD/BDB

ITEM UNIT QUANTITY UNIT

NO. COST

1 Mobilization * LS 1 15,800.00$ 15,800.00$ 2 Sediment Fence for In-water Work LS 1 4,000.00$ 4,000.00$ 3 Clear Rock and Debris LS 1 2,100.00$ 2,100.00$ 4 Replace Gravel Bedding LS 1 2,000.00$ 2,000.00$

5 Re-align Steel Frame LS 1 3,200.00$ 3,200.00$

6 Repair and Replace Steel Framing Members LS 1 9,200.00$ 9,200.00$

7 Repair and Replace Access Stairs LS 1 11,000.00$ 11,000.00$ 8 New Floating Dcok (Incl. Dock Engineering) LS 1 73,700.00$ 73,700.00$ 9 Install Floating Dock LS 1 22,000.00$ 22,000.00$

10 Site Access Premium ** LS 1 12,800.00$ 12,800.00$ 11 Permitting and Engineering LS 1 25,000.00$ 25,000.00$

* 15% of total of items 2 through 9 (varies depending on estimate) ** 10% of items 2 through 9 (accounts for remote location of project)

SUB TOTAL

30% Construction Contingency

TOTAL ESTIMATE ROUNDED

Hells Canyon Boat Launch Assessment

27-May-15

TOTAL

COST

Estimate of Probable Construction Cost - Boat Dock

Facility

$235,100

$54,300

$180,800