Tactic CR-12: Mechanical Removal: Scraping, Trimming, and Brushing
Use scraping, trimming, and brushing to recover contaminants on the tundra surface while leaving as much soil as possible, to preserve live buds, roots, and rhizomes (Figs. 56—60). Mechanical removal can be used while the ground is frozen or partially thawed. Trimmers are especially effective for breaking up contaminated ice and packed snow. Mechanical removal can also be effective in spring when air temperatures are still well below freezing, but solar heating is sufficient to thaw the surface soil after snow has been removed. Contaminants can be easier to see when soil is partially thawed (Figs. 61 and 62), and a spotter can direct the operator, but the depth of removal must be controlled carefully to minimize tundra damage. This tactic works best for viscous substances, such as crude oil, which tend to remain on the tundra surface rather than penetrating into the soil.
Damage from scraping and trimming can be severe in moist and dry tundra, because the plants’ rooting systems are often within 1 inch of the tundra surface. In contrast, much of the rooting systems of plants in wet tundra are deeper than 1 inch below the tundra surface, and are more likely to be left in place after mechanical removal.
Use a mechanical brush to clear the area of snow (Tactic CR-3) and expose the tundra surface (Fig. 63). Trimmed ice and snow can be removed with a Super Sucker vacuum truck or by methods described in the snow removal tactic (Tactic CR-3). Adjust the blade or trimmer to remove a thin layer of soil. Transfer contaminated material to dump trucks and transport to appropriate waste disposal facilities.
Considerations and Limitations
- Identify the disposal method or facility to be used and estimate the volume requiring disposal before mechanical removal begins.
- Most or all lichens and mosses will be removed by scraping and trimming.
- Scraping and trimming may be impractical for areas with small-scale topographical relief (e.g., tussock tundra, patterned ground).
- Avoid stockpiling clean snow on contaminated areas. Snow piles will persist into the growing season and inhibit vegetation recovery.
- Use of vehicles and heavy equipment on tundra must comply with applicable tundra travel policies (Tactic P-5).
- Trimming should be employed as soon as possible following the gross removal of the non-frozen spilled substance, to limit vertical movement of contamination.
- This tactic is not intended to remove pooled product from the ground surface.
- To avoid damage to the root mat, trimming should be limited to the tops of the plant shoots.
- Method of trimming, including equipment, materials and personnel, will be determined by the size and topography of the site.
Equipment, Materials, and Personnel
- Trimmer (one operator) – to trim the spill-affected surface ice (size of trimmer will be dependent on size of spill and topography).
- Grader/dozer/Bobcat (1 operator) – to scrape snow and contaminated surface vegetation.
- Spotter - to visually identify boundaries where scraping or trimming is needed.
- Front-end loader and/or Super Sucker (one to two operators) – to pick up trimmed or scraped ice and snow.
- Brooms, rakes, and shovels (one worker per
tool) – to sweep up loose ice and snow not picked up by previous methods.
- Front-end loader (1 operator) – to transfer scraped or trimmed material into end dumps.
- Dump truck (1 operator) – to transfer scraped or trimmed material to disposal site.