E. Timber Harvesting

The timber harvesting management measure consists of implementing the following:

Timber harvesting operations with skid trails or cable yarding follow layouts determined under Management Measure A.
Install landing drainage structures to avoid sedimentation to the extent practicable. Disperse landing drainage over sideslopes.
Construct landings away from steep slopes and reduce the likelihood of fill slope failures. Protect landing surfaces used during wet periods. Locate landings outside of SMAs.
Protect stream channels and significant ephemeral drainages from logging debris and slash material.
Use appropriate areas for petroleum storage, draining, dispensing. Establish procedures to contain and treat spills. Recycle or properly dispose of all waste materials.
For cable yarding:

Limit yarding corridor gouge or soil plowing by properly locating cable yarding landings.
Locate corridors for SMAs following Management Measure B.
For groundskidding:

Within SMAs, operate groundskidding equipment only at stream crossings to the extent practicable. In SMAs, fell and endline trees to avoid sedimentation.
Use improved stream crossings for skid trails which cross flowing drainages. Construct skid trails to disperse runoff and with adequate drainage structures.
On steep slopes, use cable systems rather than groundskidding where groundskidding may cause excessive sedimentation.

1. Applicability

This management measure pertains to lands where silvicultural or forestry operations are planned or conducted. It is intended to apply to all harvesting, yarding, and hauling conducted as part of normal silvicultural activities on harvest units larger than 5 acres. This measure does not apply to harvesting conducted for precommercial thinnings or noncommercial firewood cutting.

Under the Coastal Zone Act Reauthorization Amendments of 1990, States are subject to a number of requirements as they develop coastal nonpoint source programs in conformity with this measure and will have some flexibility in doing so. The application of this management measure by States is described more fully in Coastal Nonpoint Pollution Control Program: Program Development and Approval Guidance, published jointly by the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce.

2. Description

The goal of this management measure is to minimize sedimentation resulting from the siting and operation of timber harvesting, and to manage petroleum products properly.

Logging practices that protect water quality and soil productivity can also reduce total mileage of roads and skid trails, lower equipment maintenance costs, and provide better road protection and lower road maintenance. Careful logging can disturb soil surfaces as little as 8 percent, while careless logging practices can disturb soils as much as 40 percent (Golden et al., 1984). In the Appalachians, skid roads perpendicular to the contour, instead of along the contour, yielded 40 tons of sediment per acre of skid road surface (Hornbeck and Reinhart, 1964). Higher bulk densities and lower porosity of skid road soils due to compaction by rubber-tired skidders result in reduced soil infiltration capacity and corresponding increases in runoff and erosion (Dickerson, 1975). Douglass and Swank (1975) found that poor logging techniques increased sediment production during storms by 10 to 20 times more than sediment production from the undisturbed control watershed. A properly logged watershed experienced only slightly increased sedimentation compared to the undisturbed control watershed.

Locating landings for both groundskidding and cable yarding harvesting systems according to preharvest planning minimizes erosion and sediment delivery to surface waters. However, final siting of landings may need to be adjusted in the field based on site characteristics.

Landings and loading decks can become very compacted and puddled and are therefore a source of runoff and erosion (Golden et al., 1984). Practices that prevent or disperse runoff from these areas before the runoff reaches watercourses will minimize sediment delivery to surface waters. Also, any chemicals or petroleum products spilled in harvest areas can be highly mobile, adversely affecting the water quality of nearby surface waters. Correct spill prevention and containment procedures are therefore necessary to prevent petroleum products from entering surface waters. Designation of appropriate areas for petroleum storage will also minimize water quality impacts due to spills or leakage.

3. Management Measure Selection

This management measure is based on the experience and information gained from studies and from States using similar harvesting practices. Many studies have evaluated and compared the effects of different timber harvest techniques on sediment loss (erosion), soil compaction, and overall ground disturbance associated with various harvesting techniques. The data presented in Tables 3-35 through 3-40 were compiled from many different studies conducted throughout the United States and Canada. Many local factors such as climatic conditions, soil type, and topography affected the results of each study. The studies also examined harvesting techniques under a variety of conditions, including clearcuts, selective cuts, and fire-salvaged areas. However, the major conclusions from the studies on the relative impacts of different timber harvesting techniques on soil erosion and the causes and consequences of ground disturbance remain fairly constant between the studies and enable cross-geographic comparison.

[ Table 3-35 (12k) ] [ Table 3-36 (12k) ] [Table 3-37 ] [ Table 3-38 ] [ Table 3-39 ] [ Table 3-40 (12k) ]

Some of the most significant water quality impacts from logging operations (especially increased sedimentation) result from the actual yarding operations and activities on landings. The critical factors that affect the degree of soil disturbance associated with a particular yarding technique include the amount of disturbance caused by the yarding machinery itself and the amount of road construction needed to support each system. Stone (1973) presented information suggesting that roads may contribute greater than 90 percent of the sedimentation problems associated with logging operations. Therefore, since road areas represent potential erosion sites, it is important to recognize and consider the amount of land used for roads by various logging systems (Sidle, 1980).

a. Effectiveness Information

The amount of total soil disturbance varies considerably between the different yarding techniques. Megahan (1980) presented the most comprehensive survey of the available information on these impacts, presenting the data in two ways: soil disturbance associated with the actual yarding operation and soil disturbance associated with the construction of roads needed for the practice (Tables 3-35 (12k) and 3-36 (12k)). The results of his investigation echoed other studies presented in this section and clearly show that aerial and skyline cable techniques are far less damaging than other yarding techniques.

The amount of soil disturbance by yarding depends on the slope of the area, volume yarded, size of logs, and the logging system. Table 3-36 (12k) presents data on the extent of soil disturbance associated with particular yarding systems. Megahan's ranking of yarding techniques (from greatest impact to lowest impact) based on percent area disturbed is summarized as follows: tractor (21 percent average), ground cable (21 percent, one study), high-lead (16 percent average), skyline (8 percent average), jammer in clearcut (5 percent, one study), and aerial techniques (4 percent average).

The amount of road required for different yarding techniques varies considerably. Sidle (1980) defined the amount of land used for haul roads by various logging methods. Skyline techniques require the least amount of road area, with only 2-3.5 percent of the land area in roads. Tractor and single-drum jammer techniques require the greatest amount of road area (10-15 and 18-24 percent of total area, respectively). High-lead cable techniques fall in the middle, with 6-10 percent of the land used for roads. Megahan (1980) concluded that tractor, jammer, and high-lead cable methods result in significantly higher amounts of disturbed soil than do the skyline and aerial techniques.

Sidle (1980) also presented data showing that tractors cause the greatest amount of soil disturbance (35 percent of land area) and soil compaction (26 percent of land area). Sidle (1980) concluded that skyline and aerial balloon techniques created the least disturbance (12 and 6 percent, respectively) and compaction (3 and 2 percent, respectively) (Table 3-37).

Miller and Sirois (1986) compared the land area disturbed by cable, skyline, and groundskidding systems (Table 3-38). They found groundskidding operations to affect 31 percent of the total land area, whereas cable yarding only affected 16 percent of the total land area. Similarly, Patric (1980) found skidders to serve the smallest area per mile of road (20 acres), with skyline yarding serving the largest area per mile of road (80 acres) (Table 3-39).

b. Cost Information

The costs and benefits of rehabilitation of skid trails by planting hardwood, hardwood pine, and shortleaf pine in the southeastern United States were studied by Dissmeyer and Foster (1986). The average rehabilitation cost per acre was $360 and included water barring, ripping or disking, seeding, fertilizing, and mulching where needed (Table 3-40). The benefit/cost ratio of the rehabilitation cost was $1.33 for hardwood, $2.82 for hardwood pine, and $5.07 for shortleaf pine. The real rate of return over inflation ranged from 2.4 to 4.8 percent.

4. Practices

As discussed more fully at the beginning of this chapter and in Chapter 1, the following practices are described for illustrative purposes only. State programs need not require implementation of these practices. However, as a practical matter, EPA anticipates that the management measure set forth above generally will be implemented by applying one or more management practices appropriate to the source, location, and climate. The practices set forth below have been found by EPA to be representative of the types of practices that can be applied successfully to achieve the management measure described above.

a. Harvesting Practices

Fell trees away from watercourses, whenever possible, keeping logging debris from the channel, except where debris placement is specifically prescribed for fish or wildlife habitat (Megahan, 1983).

Any tree accidently felled in a waterway should be immediately removed (Huff and Deal, 1982).

Remove slash from the waterbody and place it out of the SMA.

This will allow unrestricted water flow and protection of the stream's nutrient balance. Remove only logging-generated debris. Leave pieces of large woody debris in place during stream cleaning to preserve channel integrity and maintain stream productivity. Bilby (1984) concluded that indiscriminate removal of large woody debris can adversely affect channel stability. Table 3-41 presents a possible way to determine debris stability.

b. Practices for Landings

Landings should be no larger than necessary to safely and efficiently store logs and load trucks.

Install drainage and erosion control structures as necessary.

Diversion ditches placed around the uphill side of landings minimize accumulation of water on the landing. Landings should have a slight slope to facilitate drainage. Also, adequate drainage on approach roads will prevent road drainage water from entering the landing area.

The slope of the landing surface should not exceed 5 percent and should be shaped to promote efficient drainage.

The slope of landing fills should not exceed 40 percent, and woody or organic debris should not be incorporated into fills.

If landings are to be used during wet periods, protect the surface with a suitable material such as wooden matting or gravel surfacing.

Install drainage structures for the landings such as water bars, culverts, and ditches to avoid sedimentation. Disperse landing drainage over sideslopes. Provide filtration or settling if water is concentrated in a ditch.

Upon completion of harvest, clean up landing, regrade, and revegetate (Rothwell, 1978).

Upon abandonment, minimize erosion on landings by adequately ditching or mulching with forest litter.
Establish a herbaceous cover on areas that will be used again in repeated cutting cycles, and restock landings that will not be reused (Megahan, 1983).
If necessary, install water bars for drainage control.

Locate landings for cable yarding where slope profiles provide favorable deflection conditions so that the yarding equipment used does not cause yarding corridor gouge or soil plowing, which concentrates drainage or causes slope instability.

Locate cable yarding corridors for streamside management areas following Management Measure B components. Yarded logs should not cause disturbance of the major channel banks of the watercourse of the SMA.

c. Groundskidding Practices

Skid uphill to log landings whenever possible. Skid with ends of logs raised to reduce rutting and gouging.

This practice will disperse water on skid trails away from the landing. Skidding uphill lets water from trails flow onto progressively less-disturbed areas as it moves downslope, reducing erosion hazard. Skidding downhill concentrates surface runoff on lower slopes along skid trails, resulting in significant erosion and sedimentation hazard (Figure 3-25). If skidding downhill, provide adequate drainage on approach trails so that drainage does not enter landing.

Skid perpendicular to the slope (along the contour), and avoid skidding on slopes greater than 40 percent.

Following the contour will reduce soil erosion and encourage revegetation. If skidding must be done parallel to the slope, then skid uphill, taking care to break the grade periodically.

Avoid skid trail layouts that concentrate runoff into draws, ephemeral drainages, or watercourses. Use endlining to winch logs out of SMAs or directionally fell trees so tops extend out of SMAs and trees can be skidded without operating equipment in SMAs. In SMAs, trees should be carefully endlined to avoid soil plowing or gouge.

Suspend groundskidding during wet periods, when excessive rutting and churning of the soil begins, or when runoff from skid trails is turbid and no longer infiltrates within a short distance from the skid trail. Further limitation of groundskidding of logs, or use of cable yarding, may be needed on slopes where there are sensitive soils and/or during wet periods.

Retire skid trails by installing water bars or other erosion control and drainage devices, removing culverts, and revegetating (Rothwell, 1978; Lynch et al, 1985).

After logging, obliterate and stabilize all skid trails by mulching and reseeding.
Build cross drains on abandoned skid trails to protect stream channels or side slopes in addition to mulching and seeding.
Restore stream channels by removing temporary skid trail crossings (Megahan, 1983).
Scatter logging slash to supplement water bars and seeding to reduce erosion on skid trails (Lynch et al., 1985).

d. Cable Yarding Practices

Use cabling systems or other systems when groundskidding would expose excess mineral soil and induce erosion and sedimentation.

Use high-lead cable or skyline cable systems on slopes greater than 40 percent.
To avoid soil disturbance from sidewash, use high-lead cable yarding on average-profile slopes of less than 15 percent.

Avoid cable yarding in or across watercourses.

When cable yarding across streams cannot be avoided, use full suspension to minimize damage to channel banks and vegetation in the SMA.

Yard logs uphill rather than downhill.

In uphill yarding, log decks are placed on ridge or hill tops rather than in low-lying areas (Megahan, 1983). This creates less soil disturbance because the lift imparted to the logs reduces frictional resistance and the outward radiation of yard trails downhill from the landing disperses runoff evenly over the slope and reduces erosion potential. Downhill yarding should be avoided because it concentrates surface erosion.

e. Petroleum Management Practices

Service equipment where spilled fuel and oil cannot reach watercourses, and drain all petroleum products and radiator water into containers. Dispose of wastes and containers in accordance with proper waste disposal procedures. Waste oil, filters, grease cartridges, and other petroleum-contaminated materials should not be left as refuse in the forest.

Take precautions to prevent leakage and spills. Fuel trucks and pickup-mounted fuel tanks must not have leaks.

Use and maintain seepage pits or other confinement measures to prevent diesel oil, fuel oil, or other liquids from running into streams or important aquifers.
Use drip collectors on oil-transporting vehicles (Hynson et al., 1982).

Develop a spill contingency plan that provides for immediate spill containment and cleanup, and notification of proper authorities.

Provide materials for adsorbing spills, and collect wastes for proper disposal.

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This page last updated October 4, 1999