Alternate testing for tundra hardness to be compared with DNR methods

ConocoPhillips would begin one stretch of road based on new test; next summer comparisons would be made with road built after traditional test for tundra travel

Kristen Nelson

PNA Editor-in-Chief

More details are available on ConocoPhillips Alaska Inc.’s plan to build a demonstration ice road section west of the Kuparuk River unit which will test alternative methods to determine when the tundra is sufficiently hard for winter travel. (See brief in Oct. 13 issue of PNA.)

In September applications to state, federal and North Slope regulators the company said it is developing new methods to evaluate when tundra can support ice-road construction because of the short time available for winter travel on the North Slope.

Department of Natural Resources records for tundra travel go back to 1969, and through 1983, the tundra travel opening was in early to mid-November. In 1985 and 1990 the opening wasn’t until January, and late November and December dates were routine through the early 1990s. Every year but one (1999) beginning in 1997, however, tundra travel has opened in January. This year the opening, Jan. 25, was the latest on record.

DNR has required at least 12 inches of frozen ground and six inches of snow for ice road construction and while the test road would still require six inches of snow, the 12 inches of frozen ground test would be replaced with cone penetrometer and plate indentation methods. Both tests, ConocoPhillips said, “are operator independent, objective, and produce a record that can be easily referenced.”

The cone penetrometer, used in soil mechanics to determine foundation stability, uses a one-inch diameter probe pushed into the soil. The depth and the and force required are recorded for further analysis. If large variations are encountered when using the core penetrometer, core samples can also be collected.

The plate indentation method “was developed to determine when the soil is able to support the pioneering ice road construction equipment,” ConocoPhillips said. A load is applied to a circular plate and “the short-term time dependent deformation of the tundra is recorded.” The plate indentation method “is a representation of wheeled vehicle loads on soils,” the company said.

When can ice road work begin?

To assess the new methods, ConocoPhillips is proposing a demonstration project to compare the new methods with the DNR’s traditional methods, comparing impacts of an ice road constructed based on the new assessment method with an ice road constructed after DNR approves winter travel.

In addition to the new test criteria, the company said, there will also have to be six inches of snow on the ground, which is part of the traditional criteria for tundra travel.

Test sections offset from previous ice road routes

The selection of routes also included the presence of similar vegetation types for both treatments and the fact that the roads will be used for travel between Kuparuk and Alpine, allowing both portions of the route to have similar rates of winter vehicle traffic.

Before ice road construction begins, both cone penetrometer and plate indentation tests will be done. Once these tests are complete, a representative from DNR will collect ground hardness information using the slide hammer probe traditionally used by DNR in its tundra travel determination. Then ConocoPhillips will begin construction of the first demonstration ice road. The company said sampling locations will be approached at an angle perpendicular to the ice route road to avoid compacting snow along the route.

In the summer of 2003, two types of testing will be done at the two sections of road with 18 sampling locations at each of the two ice roads, each including six per vegetation type (tussock tundra, moist tundra and wet tundra) and 18 locations (six per vegetation type) in adjacent undisturbed tundra.

DNR proposes tundra opening by areas

Currently the division determines a single date when it allows winter off-road vehicle travel on state-owned land on the North Slope, requiring that the ground is sufficiently frozen to support vehicles and heavy equipment. Typically this means the snow depth must be at least six inches and the ground must be hard frozen to a depth of 12 inches and when this occurs over a broad area, the division allows off-road travel to begin.

Instead of waiting for conditions to be suitable across the entire North Slope, the division is proposing four geographic area tundra openings:

• Western coastal area: between the Colville and Kuparuk rivers and from the coast to the southern limit of the Alaska Coastal Management Program coastal zone, roughly 20 miles from the coast;

• Eastern coastal area: between the Kuparuk and Canning rivers and from the coast to the southern limit of the ACMP coastal zone;

• Lower foothills area: Between the Colville and Canning rivers from the southern limit of the ACMP coastal zone to a line that approximates the 500-foot contour;

• Upper foothills area: Between the Colville and Canning rivers south of the lower foothills area to 68 degrees N. Latitude.

Comments concerning this proposal should be submitted in writing by Oct. 25 to Gary Schultz, Division of Mining, Land and Water, Department of Natural Resources, 3700 Airport Way, Fairbanks AK 99709.