Review the planning considerations for constructing roads, as these will likely be applicable to landings too. The factors that are specific to landings or are worth reiterating when planning landing layout include:
- Topographical constraints, like steepness of terrain, geology and soils, which may constrain size, shape and access points
- Designing the landing and road location to ensure that the road adverse grade off the landing does not exceed 6% in the first 30 m. If it does, then road design and pavement accounts for truck egress. Design the favourable grade to be less than 12%
- Environmental constraints, including water control, slash location and diesel storage
- Types of machinery to be used on the landing. For example, yarder versus skidder, yarder type and configuration, rubber-tyre front-end loader versus excavator
- Processing area requirements. For example, conventional landing, two-stage landing, or at a central processing yard
- General storage requirements like number and size of log stacks and sorts
- Tree length. For example, at least two thirds of the stem/drag to be able to be landed safely and securely
- Loading out location and truck access
- Machinery production and likely bottle neck location
- Crew requirements including parking, storage container, smoko hut.
The selection of the final landing location may be the result of a compromise between the factors listed above. For example, steep, knife-edged ridges may require landings to be located back from the preferred site in order to build a landing of large enough size. Also, sometimes plans change so design criteria need to be flexible – especially since there may be two years or more between planning, construction and harvesting. For example, the landing may have been designed for a 26 m (85 ft) tower yarder for deflection, but operational scheduling means that only a 21 m (70 ft) tower is available.
Be aware that deployment of a shorter tower may be interpreted by councils as a notifiable material change to a harvest plan under the NES-PF. This could result in an abatement notice being served if the NES-PF’s requirement for log butt suspension, wherever practicable, cannot be maintained during yarding. This could lead to excessive ground disturbance, meaning that permitted activity Regulation 67 is breached.
Calculating landing earthworks is challenging unless you use road engineering design software. Where road egress off the landing is critical, it is essential to design the road and landing as part of the overall infrastructure design. In steep country where ridges are narrow, the constructed landing level could be way below the ridge crest. Unless the planner has anticipated the depth of cut correctly, an adverse road grade is likely to steepen. If the grade is already steep it will be constructed steeper. Operationally this may be fine in good weather but poor weather can lead to issues like having to do truck assists.
4.2.1 Landing size and shape
The efficiency of a harvesting operation is often very dependent on the configuration of the landing site. On average, landings are rectangular in shape and twice as long as wide, but landings for cable yarding operations are approximately 2.5 times as long as wide.
Design the landing shape to safely optimise the flow of logs through the work area, given the landform and other construction constraints. In many situations, the physical construction of the ideal landing is limited by site topography constraints. Therefore, the design of landings requires close liaison between the harvest planner, operations co-ordinators, and the logging and roading contractors.
Many serious work accidents and fatalities have been on landings. Some of these have been due to poor landing design and layout. It is essential that the planner understands their health and safety obligations when designing landings. Refer to WorkSafe’s Approved Code of Practice for Safety and Health in Forest Operations (ACOP). Also, some forest company’s health and safety manuals may have specific requirements too. WorkSafe requires that all landings shall be planned and constructed to allow safe operations to allow for:
- Stems, stockpiles and log stacks
- Safe areas
- Vehicle parking
- Fuel and chemical storage
- Load-out areas
- Where applicable, the yarder to be safely positioned, with at least two thirds of the stem/drag to be landed safely and securely
- Truck turn around.
Two typical design standards for landing size are 40 m x 60 m (= 2,400 m2) for small, or 40 m x 80 m (= 3,200 m2) for medium sized landings. However, a 2010 survey of landings indicated that the average landing size is now 3,900 m2 – considerably larger than the design standards (FFR, 2010). A survey by Raymond (1987) indicated they were 1,900 m2, showing they have doubled in size over the last 20 years. Much of the increase in size, can be explained by the increased productivity of our typical harvest systems, as well as the need to work with much larger numbers of different log sorts. Both studies showed that the larger the operation, the higher the space requirements.
A basic equation that can be used to compare landing size is:
Landing size (m2) = 390 + 3.5 x Daily prod
(m3/day) + 173 x No. Log Sort.
Other factors, such as machinery type, also affect landing size. For example, landings using front-end loaders instead of knuckle-boom loaders will need more space to operate. Landings may also ‘grow’ in size with the operation, especially ground-based logging, as contractors make more space to accommodate log stacks. On average, a landing that has been used is 900 m2 larger than a new landing, indicating that the contractors increase the size of landings during harvesting operations. This may be to accommodate additional log stacks, make space for new equipment, or simply side-casting material off the surface of the landing in the process of cleaning it up.
Reviewing recently harvested areas, including talking to operational staff and contractors, will also help identify what shape and size is effective and, as importantly, what aspects could be improved.
Safety is a prime consideration in layout.
Safe cable logging layout example
4.2.2 Harvest residue (slash) management
Log processing can produce lots of slash and log waste, often referred to as harvest residue. It is estimated that on average 15% of the total volume will become harvest residue. The volume of slash generated, as well as the proportion that ends up on the landing, will depend on factors like the setting area, type of trees harvested, log grades specified, and the harvesting system used. It is essential that, if residues are not carted off-site, provision is made for disposal of slash in an appropriate place in the landing design. Slash must be located to avoid risk of mobilising into waterways, riparian areas, wetland or other sensitive sites, or where it could migrate off-site and effect adjacent neighbours and infrastructure.
Key planning considerations include:
- Ensure there is enough suitable area for slash, so it is not deposited in unsuitable locations. If not, locate a stable location to cart off-site
- Don’t locate slash where it will load fill slopes that could lead to landing collapse. Make sure planning maps have clearly marked areas that are not acceptable to dump slash
- Identify areas where slash will be retrieved during post-harvest rehabilitation. Slash will rapidly go beyond the reach of the cleanup excavator if too much is pushed or placed there
- Manage water control around slash piles. Water that drains onto wrong places like through, or over large fills, will weaken and load the slope where the slash is located and increase the risk of fill failure
- Where possible, locate slash disposal sites that are less visible to public to reduce visual impact.
Planners should also consider opportunities to remove slash from landing as part of a biomass recovery operation. In some parts of the country this is a potential opportunity. Biomass will reduce environmental impacts from slash storage and also reduce the fire risk.
Burning is another tool that can effectively reduce the slash loading on landings. Burning can be challenging and risky unless it is managed carefully by experienced operational staff. Major forest fires have been accidently started through burning slash on landings. Landing fires can take weeks to burn out.
The FOA Forest Practice Guides (FPGs) provide more detailed guidance on slash management.