Engineering for Marine Resupply Relocation in Kugluktuk, Nunavut

PRELIMINARY ENGINEERING FOR MARINE RESUPPLY RELOCATION IN THE COMMUNITY OF KUGLUKTUK, NUNAVUT TERRITORY Christopher Wright, Mariport Group Ken Johnson, UMA Engineering Ltd. ABSTRACT The Hamlet of Kugluktuk is located on the shore of Coronation Gulf immediately west of the mouth of the Coppermine River at 68 degrees north latitude, and 115 degrees west longitude. Concerns have developed within the community over several aspects of the current marine resupply system, which include the barge access to the current resupply dock structure, the location of existing resupply pipelines through the community, and space available for efficient and safe dry cargo laydown.

UMA Engineering Ltd., the Kitikmeot Corporation, Roosdahl Engineering Enterprises and the Mariport Group were retained in 1998 by the Government of the Northwest Territories to undertake a study of relocating the resupply facility. The initial phase of the project completed a Feasibility Study of potential new locations, and recommended one particular location based upon the “land side” elements, as well as the “water side” elements. Integral to this process was input on community desires, and user requirements.

A second phase of the project completed a Preliminary Engineering assessment of a breakwater construction, a dock construction, a cargo laydown area and a fuel resupply pipeline relocation. The assessment included a preliminary engineering cost estimate and schedule for the construction of a new facility.

1.0 INTRODUCTION 1.1

Basis for Study

The Hamlet of Kugluktuk, in the Nunavut Territory, is a community of about 1,300 people (1998) located on the shore of Coronation Gulf immediately west of the mouth of the Coppermine River Latitude 68º north latitude, 115º west longitude. The settlement stretches for 800 metres along the sandy foreshore of the Gulf, and extends 800 metres inland.

The community of Kugluktuk has expressed concern over two aspects of the current resupply system. These concerns are: 

The existing oil pipelines from the resupply site for the two community tank farms currently run through the centre of the community, and conflict with the community land use desires, and are an environmental concern.



Insufficient space is available adjacent to the existing resupply location for efficient and safe dry cargo laydown.

Marine resupply services to Kugluktuk are supplied by the Northern Transportation Company Limited (NTCL) from Hay River, NWT. The short navigation season generally lasts from the end of July to the end of September, and supply barges arrive during August and early September. Under favourable ice conditions, barges can reach Kugluktuk by the third week of July.

1.2

Natural Environment

The prevailing winds in Kugluktuk are generally from the north and east during the summer months. Wind speeds are relatively constant throughout the year at approximately 16 km/h, with very few periods of calm. Temperatures range from mean daily maximums and minimums of -27.2°C and -35.4°C respectively in February, to mean daily highs and lows of 12.8°C and 5.0°C respectively in July.

Ice normally covers the Coronation Gulf from October to July. However, flow of the Coppermine River causes the ice to break up in front of the settlement by mid June, while the ice several miles offshore remains solid, thus limiting navigation. At its junction with Coronation Gulf, the Coppermine River is about 2 kilometres wide with many sandbars close to the community.

The tidal variation at Kugluktuk is 0.3 metres. Local water levels are affected more by winds than by tides, and a strong northwest wind of a few days duration may raise water levels as much as 1.2 metres.

1.3

Marine Resupply Activity

The existing resupply site in Kugluktuk is located in a busy area of the community adjacent to the Northern Store, and an area used by boaters. NTCL finds it difficult at times to reach the site because of sandbars created by the Coppermine River. According to NTCL, this access difficulty occurs in a cycle of every 5 to 6 years.

The two tank farms, which are separate facilities, are both resupplied from the existing dock facility with resupply pipelines running through the centre of the community. One tank farm is on the east side of the community, and the other tank farm is on the west side of the community.

The demand for dry cargo over the last five years has been about 3 tonnes per capita per year; the expected normal value for a community such as Kugluktuk is about 2 tonnes per capita. With the expected population growth, the quantity of dry cargo to be shipped into the community for normal resupply needs will be in the order of 2,800 tonnes each season by the year 2000, and 3,200 tonnes by the year 2006.

Wet cargo demand for diesel, mogas, jet and Avgas will also increase in line with population. Current demand averages just over 3 tonnes per capita and quantities shipped in by 2006 could be in excess of 5,400 tonnes each season.

Based on these forecasts, and a current expectation of six barge loads per season in three calls (about 1,000 tonnes/barge), the demand will increase by eight barge loads per average season. This will significantly increase space demand in the laydown area because the ordinary delivery strategy is to bring as much deck cargo in as possible on the first trip.

2.0 FEASIBILITY EVALUATION 2.1

Site Selection

Five sites, including the existing site, were selected during the Feasibility Evaluation (see Figure 1). The sites were selected based upon discussions and site reconnaissance in Kugluktuk with Community Council Members, Department of Transportation Officials and NTCL. officials. The sites were further evaluated by a Port Planner to develop the summary presented in Table 1. The evaluation included “land side” elements of location, adjacent land use, access and site suitability; and “water side” elements of marine access and wind protection. Based upon the evaluation, Sites #2 and #5 were recommended for preliminary engineering consideration, and presented to the community at a public meeting.

Site #2 would accommodate both wet and dry cargo, whereas Site #5 would serve wet cargo only resupply to the east tank farm.

TABLE 1 – FEASIBILITY EVALUATION OF PROPOSED RESUPPLY SITES

SITE #1

SITE #2

SITE #3

SITE #4

SITE #5

No

Probable

No

No

No

Partial

Partial

Yes

Yes

Yes

Long term stability regarding siltation

Probable

Probable

No

No

No

Adequate area for current and future laydown

Possible

Yes

No

No

No

Proximity to community

Fair

Fair

Good

Good

Good

Ability for expansion

Yes

Yes

No

No

No

Ability to handle future shipping need, e.g. cruise

No

Unlikely

No

No

No

Meets land use plan

Yes

Yes

No

No

Yes

Safe community development

Yes

Yes

No

No

Yes

Separates freight and fuel ops

Yes

Yes

Yes

No

Yes

Unknown

Unknown

Unknown

Unknown

Unknown

Yes

Yes

Yes

No

Yes

Probable

Probable

Possible

Unlikely

Possible

No

Probable

No

No

No

Safe marine access, all states of tide Reasonably protected

Land ownership clear and transfer possible Removes environmental hazards Establishes an operation that meets safety & pollution abatement required Provides for safe marine & land access

2.2

Effect of Weather on Resupply Operations and Relocation

Marine resupply to Kugluktuk is typically completed during the August to mid September period. During the resupply, winds are from east through southwest approximately 40% of the time. The current resupply point, at Site #4, is well protected from winds from north through east, and this same level of protection would apply to Site #5. Site #4, and to a greater extent Site #5, also has some limited protection from the west. As the supply point moves west, there is decreasing protection, unless this protection is built into the dock itself.

Site #2 will have protection from the land from east through the west, equivalent to Site #4.

However, protection from north through northeast would have to be built into the dock. This location is also fully exposed to winds in the north through northwest quadrant with about a three mile fetch.

2.3

Impact on Pipeline Access to Tank Farms by Relocation

The relocation will improve pumping to both tank farms. Relocation to Site #2 should reduce the pipeline length from 1,500 m to 500 m for the west tank farm. For the east tank farm, relocation in the vicinity of Site #5 should reduce the length from 1,000 m to 600 m.

An alternative pipeline route for the east tank farm, if Site #5 is not used, would be via the west tank farm, following the current pipeline. If both Sites #2 and #5 are developed, the fuel resupply would become a split discharge.

2.4

Impact on Resupply Operations by Relocation

There are some inefficiencies associated with split fuel resupply discharge by implementing both Sites #2 and #5, in that the barge at the remote location will need watchmen and a pumpman that cannot be readily based on the tug. However, the proposed relocation provides for a much shorter pumping time for fuel cargoes due to a shorter pipeline. Also, deck cargo handling with a dock, associated with an effective laydown area, will enable operation to be undertaken much faster. Organizing the sequence of discharge activities to take advantage of the facilities should result in a shorter resupply time, despite having to split the fuel resupply discharge.

2.5

Community Impact

The primary impact to the community will come from development opportunities following removal of the pipelines. Kugluktuk needs to develop about 15 lots each year to accommodate both natural expansion of the hamlet, and pent up demand. In addition there will be a short term population expansion over the 1999/2000 period as a result of Nunavut administrative requirements. Pipeline removal is expected to free up a number of lots in the hamlet that are currently undevelopable.

The construction of the dock, and related works, would also directly benefit the hamlet in that the design maximizes locally available resources using local equipment. As a result approximately 80% of the estimated cost would be spent in the community.

3.0 PRELIMINARY ENGINEERING 3.1

Objectives

The following preliminary engineering objectives were utilized in completing the preliminary engineering assessment of Site #2:     

3.2

The facility construction should maximize the use of locally available resources and labour.

The facility construction should avoid structures that require specialized construction techniques.

The structures should provide reasonable protection for the tug and barges during resupply discharge operations and be able to withstand environmental loads (waves, ice) during the remainder of the year.

The structures should be relatively inexpensive to build and maintain, and should have a relatively long design life.

The associated laydown area for dry cargo should offer about 12,000 m2 of level ground, and should be reasonably accessible to the community.

Bathymetry and Marine Environment

The bathymetry along the waterfront area of Site #2 indicates a large shoal area approximately 150 m offshore running parallel to the shore, with water depths of up to 2 m.

This bathymetry may accommodate site development as a partially sheltered harbour by incorporating the shoal into a breakwater.

Construction of any structure in the water along a beach will have an impact on the dynamic processes of the coastline and offshore environments. Consideration of the prevalent conditions in relation to potential harbour structures is vital to ensure the facility remains in operation over the long term. The Kugluktuk beach site is subjected to significant wave energy, littoral drift and longshore currents; however, there is no evidence to suggest that ice is a problem.

3.3

Breakwater and Dock

The primary requirement in the proposed location is to identify the breakwater design parameters that will be dictated by wind directions, wind speed and fetch (see Figure 2). The control parameters for the breakwater are the height of the expected wave, and thus the size of the breakwater (height and width) relative to the marine equipment that the breakwater is protecting.

The preliminary analysis produced a breakwater design that is 320 m long, to be constructed from quarry run rock. The crest is 2.5 m above mean sea level and 8m wide.

Given the fetch and wind speeds, the maximum wave that the breakwater is designed to handle is 2 m. This calculation is based upon a rigorous mathematical formulation developed by the US Army Corps of Engineers. Maximum waves out of the northwest are expected to

be about 1 m, and while the breakwater may provide some protection, the dock may not be functional under these conditions. However, this is the maximum wave height, and this condition would occur infrequently. Given the average conditions, the typical waves will be 0.24 m in height with a short period which will not significantly affect operations.

The dock would be designed as a timber crib structure. Cribs are normally built from 300 mm x 300 mm (12” x 12”) treated timbers and could be expected to have a design life of 20 years or more. The existing dock is a timber crib and, although it may be over 30 years old, is still serviceable. The crib would be placed onto a stone mattress and ballasted into place with stone. The apron would then be dumped behind the crib face.

3.4

Laydown Area

The laydown area would be excavated into the embankment below the adjacent airport road.

The embankment would be excavated to create a positive draining area of about 12,000 m2.

The extent of area construction to the west would depend on the stability of the ground following fill placement and placing of a gravel base.

3.5

Fuel Resupply

The fuel resupply pipelines from the shore to the west tank farm would be approximately 500 m long, and consist of four separate pipelines as follows:    

One 150 mm pipeline for P-50 diesel fuel; One 100 mm pipeline for gasoline; One 100 mm pipeline for Jet A; and One 100 mm pipeline for AvGas.

The pipelines would be constructed above ground, and would rest on a welded steel frame.

The appurtenances to the pipeline would also include a spill basin and floater hose bollards.

3.6

Facility Construction and Capital Cost

Within the scope of local construction resources, a berm type breakwater is the most economic option to protect the harbour. The berm type breakwater is a dynamic structure that reshapes and stabilizes itself under the influence of wave conditions. The design of the structure will ultimately dependent upon the type, size, weight and quantity of rock material available. An efficient design will provide the necessary protection to the harbour and docks during the shipping season and withstand the environmental conditions of the remainder of the year without substantial damage. Under severe conditions, the berm type breakwater will

require some maintenance, particularly during the first few seasons after construction while the structure stabilizes. The first season after construction, it may be expected that replenishment of some areas of the structure will be required. It may be economic to recognize that the structure will require replenishment after the first year, and plan the final construction based over two seasons.

By taking advantage of the existing shore shoal, the quantity of construction materials needed may be considerably reduced. It is, however, not known how compact the in situ material of the shoal is, and therefore to what degree bottom consolidation may occur once the breakwater is constructed.

The proposed construction process is to create a dump rock causeway out to the breakwater location and then dump and shape the breakwater working away from the land. The optimal slope is 2:1 on the outside face, so some work may be needed to push the toe of the berm.

Once the breakwater is completed, the deep water channel along the shore would be reexcavated, and the resultant fill used elsewhere. This would leave a short stub of causeway to the east that should not interfere with normal beach action.

Based upon a three season construction period, the total capital cost for the new resupply facility would be $1.2 million. (See Table 2.)

Dock Apron Breakwater Access Road Laydown Area Engineering, etc.

Total Capital Cost

TABLE 2 Season 1 $146,400 $94,500 $371,000 $169,400 -$90,000 $871,300

Season 2 --$142,600 --$21,000 $163,600

Season 3 ---$198,000 -$198,000 $1,233,000