Soil Conservation Guidebook

Table of contents

3 Temporary access structures

Those on-block access structures that do not satisfy the criteria for being classified as permanent access structures are considered temporary. Temporary access structures are required only for a limited period during a specific forest management phase. The area they occupy is part of the NAR, and must be suitable for rehabilitation to enable the establishment of a commercial crop of trees.

Temporary access structures include:

The amount and types of proposed temporary access structures should be the minimum required for a safe and efficient operation. The maximum allowable level of soil disturbance specified in a prescription must accommodate the total proportion of the NAR that will be occupied by proposed temporary access structures plus any other types of soil disturbance anticipated for the NAR. However, there are provisions to allow soil disturbance limits to be exceeded in some circumstances, as described in the section "Temporarily exceeding the maximum allowable level of soil disturbance in the net area to be reforested."

Given the expense and potential difficulties associated with rehabilitating roads and landings to a productive state, it is preferable to minimize the area occupied by these structures.

Construction of temporary access structures should be proposed only where it has been determined that rehabilitation measures can be implemented to prevent soil erosion, avoid changes in drainage patterns, and restore soil productivity. For areas where ground-based harvesting is being proposed, the sensitivity of the soil to disturbance must be assessed using procedures described in the Hazard

Assessment Keys for Evaluating Site Sensitivity to Soil Degrading Processes Guidebook. Based on these assessments, a determination can be made as to whether site conditions will be suitable for conducting effective soil rehabilitation treatments.

Building temporary access structures in a manner designed to facilitate subsequent rehabilitation will increase the likelihood of the soil being restored to an acceptable level of productivity. The following are examples of construction techniques that can facilitate rehabilitation of temporary structures (other recommended treatments are presented in the Soil Rehabilitation Guidebook):

For many of the treatments noted above, a small excavator will generally be more successful than a crawler tractor. For this reason, when crawler tractors are specified in a prescription as the trail builder, special attention should be given when supervising and inspecting the construction and subsequent rehabilitation of these trails to ensure satisfactory results. This will be particularly critical if unfavourable subsoils will be excavated during construction.

In addition to requiring rehabilitation of roads that are temporary access structures, road deactivation will also be necessary. Rehabilitation is usually done concurrently with or soon after road deactivation. The primary objectives of deactivation are to stabilize the road prism and restore natural drainage patterns. The main purpose of rehabilitation is to restore long-term productivity so that a commercial crop of trees can be established. While the two have different objectives, they sometimes involve similar activities. There is a need to coordinate the two operations and be aware of the requirements of both. Deactivation of the road must be in accordance with a deactivation prescription prepared by the holder of the permit. Rehabilitation of the road must be in accordance with any requirements of the regulations.2

Excavated or bladed trails

An excavated or bladed trail is a constructed trail that has an excavated or bladed width greater than 1.5 m, and a cutbank height greater than 30 cm in mineral soil. The depth of cut into the mineral soil for these trails should typically not exceed 1 m (although there may be situations - for example, in hummocky terrain - where short sections of trail may have a greater depth of cut).

Where an unfavourable growing medium occurs less than 70 cm below the soil surface, the maximum depth of cut into the mineral soil should result in no more than 30% of the excavated material consisting of unfavourable subsoil. This will ensure that the retrievable fill slope soil material consists mainly of productive topsoil.

A situation that could be considered for an exemption from rehabilitation is where occasional blading of logging trails has resulted in short isolated portions of what would be considered excavated or bladed trails. If these excavated portions are stable, if they will not increase the risk of sediment delivery to streams, and if they account for only a small portion of the total NAR, rehabilitation may not be necessary. Ultimately, it is up to the district manager to determine whether an exemption is warranted.

Any area occupied by unrehabilitated trails must be included in the assessment of area occupied by soil disturbance, whether exempted from rehabilitation or not.

Construction of excavated or bladed trails is prohibited on sensitive soils within community watersheds, as well as on sites assessed as having a high likelihood of landslides, and in some cases sites with a moderate likelihood of landslides.

1 At the time of publication, an amendment to the regulation was pending.

2 At the time of publication, an amendment to the Timber Harvesting Practices Regulation was pending.

3 At the time of publication, an amendment to the regulation was pending.

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