Efficient soil excavation

AirVac safely uncovers underground utility lines, tree roots, or other buried facilities with efficient soil excavation. Images: Knight Pneumatics

With its innovative design, powerful performance, and versatile applications, AirSpade is an ideal tool for efficient soil excavation and tree root management.

AirSpade has become a must-have tool for companies providing tree-health management and site-construction services. Councils and shires in Australia are increasingly specifying non-destructive digging and efficient soil excavation when requesting tenders, often using AirSpade in their Tender Scope of Works.

Used correctly, the equipment is safe for both trees and personnel on site, and when paired with a standard 185cfm tow-behind air compressor, the AirSpade delivers exceptional performance and efficient soil excavation in a range of applications at remote locations.

Safe for buried, solid objects

AirSpade’s proprietary supersonic nozzle turns compressed air into a high-speed, laser-like jet that dislodges soil and is one of the best ways to minimise damage to the tree’s root system during excavation. It’ll easily and gently remove soil around tree roots for better nutrient absorption and growth, and it can dig through soil, clay, and other materials with precision and control, breaking up compacted earth and improving drainage.

Powered by an air compressor, excavation with the AirSpade offers several advantages over conventional tools such as picks, shovels, and backhoes. It’s far more efficient soil excavation – two to three times faster than hand excavation for starters – and causes less worker fatigue. There are no sharp metal edges, so AirSpade is therefore harmless to buried, solid objects such as utility lines, telecommunication cables, hazardous-waste containers, military ordnance, and, of course tree roots.

Use of an AirSpadeis the best way to minimise damage to the tree’s root system. Image: Knight Pneumatics efficient excavation
Use of an AirSpade is the best way to minimise damage to the tree’s root system. Image: Knight Pneumatics

Excavation rates

Excavation rates for the AirSpade are a function of soil type and nozzle size (air flow). Hard, stiff soils will have lower excavation rates than soft, sandy soils. For any given soil, the lower the unconfined compressive strength, the faster the digging.

As shown in the table, six standard AirSpade supersonic nozzles, ranging in size from 25cfm to 330cfm, are available. As a rule of thumb, the quantity of soil that can be excavated in a given amount of time is rough.

Six standardAirSpade supersonic nozzles , ranging in size from 25cfm to 330cfm, are available, allow Efficient soil excavation. Image: Prime Creative Media.
Six standard AirSpade supersonic nozzles, ranging in size from 25cfm to 330cfm, are available. Image: Prime Creative Media.

Benefits

Aside from minimising damage to tree roots and underground infrastructure, AirSpade offers substantial benefits over hand and power tools for excavating around and near trees, including:
• A lightweight and ergonomic design for easy handling and reduced fatigue during extended use
• Adjustable air pressure for customised performance based on the task at hand
• A safety trigger to prevent accidental operation and ensure user protection
• Durable construction for long-lasting reliability in the very toughest and most challenging working conditions, and
• Interchangeable nozzles for versatility in various applications.

Air tilling

With proper, professional, site management, efficient soil excavation with an AirSpade can be extremely effective and productive for the professional arboriculturalist.

Trees and shrubs suffering from shallow soil compaction – typically due to pedestrian use or vibrations caused by vehicular traffic – or lacking vigorous root growth due to poor topsoil quality, are ideal candidates for air tilling.

Since most of a tree’s roots proliferate near the surface where they have the best access to oxygen and nutrients, air tilling is excellent at promoting robust and uniform root growth. If it’s necessary to affect soil to a depth greater than 15cm-20cm, it’s possible to combine air tilling with other methods such as radial trenching or vertical mulching.

While the tree-health benefits of air tilling alone (decompaction and aeration) are significant, this proven method is often used for soil augmentation as well.

Radial trenching

Radial trenching with an AirSpade is done to modify soil composition, improve aeration, and encourage root growth to moderate depths, typically 25cm to 30cm or more, and is especially effective when trees have highly stratified or shallow depth of viable soil or anaerobic conditions.

Additionally, this application can be useful in planting areas where minimal disturbance is desired.

Vertical mulching

Vertical mulching with an AirSpade is done to de-compact and augment soil deep into the tree root zone.

This application is especially useful in areas with poor drainage, with shallow or impervious soils, or shared by perennial or ground-cover plantings where minimal disturbance is desired.

Aeration and soil amendments from vertical mulching can encourage roots to grow deep into the soil profile, improving the tree’s stability and the volume of viable growing medium.

Because vertical mulching affects the deepest soil profile, it is recommended for sites with shallow soil depth, hard-pan, anaerobic conditions, or other types of poor growing soils and media.

AirSpade is twoto three times faster than hand excavation and is harmless to buried, solid objects, including tree roots. It's efficient soil excavation. Image: Knight Pneumatics.
AirSpade is two to three times faster than hand excavation and is harmless to buried, solid objects, including tree roots. Image: Knight Pneumatics.

Root collar excavation

Trees commonly suffer when the grade is set too high against their root flare or root collar. This can occur when trees are planted at the wrong elevation or when trees subside due to improper compaction below the root ball when they are planted. Alternatively, root collars can be buried over time due to the accumulation of mulch or soil around the tree.

Whatever the cause, harm to the tree from grade set above the root collar can be long lasting and should be remediated through root collar excavation (RCX) with an AirSpade. Symptoms of this condition include:
• Rot or infection of bark at the base of the trunk
• Growth of roots that are too high relative to the natural root flare, and
• Girdling roots, which constrict the root flare and tree trunk.

Girdling can also occur on urban sites where roots have limited room to grow or have encountered compacted or anaerobic soil conditions. Use of an AirSpade allows tree root collars and girdling roots to be excavated with minimal damage to the tree. Once uncovered, a certified arborist can easily identify roots that need to be removed or trained, and do it with only minimal risk to the tree and root system.

Root pruning

AirSpading is safe to the tree’s roots and a highly efficient method to perform exploratory excavation to locate existing roots and utilities. Almost any site-work operations – including the building of foundations, pavements, drainage infrastructure, and utilities – present ideal opportunities for AirSpading and root pruning.

Proper root pruning will encourage future growth and minimise negative impacts to structures or utilities.

Once the existing roots have been excavated, a certified arborist can easily determine the best places to make clean cuts using a hand pruner.

Bare rooting and transplanting

Bare rooting with an AirSpade can be applied to perennial, shrub, and groundcover plantings.

It’s a preferred method of transplanting due to its efficiency and ability to preserve fine root systems. Furthermore, bare rooting small plants is often required during more extensive root-zone treatments such as aeration and decompaction or other site-work applications.

Use of an AirSpade can significantly reduce trauma to the tree.

Ideal for small-diameter, potholing where a hand shovel or backhoe bucket cannot be used. Image: Knight Pneumatics
Ideal for small-diameter, deep excavation (potholing) where a hand shovel or backhoe bucket cannot be used. Image: Knight Pneumatics

Urban tree soil replacement

Urban tree soil replacement It may be desirable to partially replace the soil around a tree’s root zone in an effort to enhance the tree’s health and lifespan.

This application is ideal for tree plantings with root zones extending underneath pavement and those that have poorly suited or limited soil volume, or where pavement is proposed to be added or replaced within an existing root zone. Similarly, this may be applied to trees planted in high-use lawn areas (for example within parks or campus landscapes,) where soil replacement is desired to improve lawn durability and health.

Learn more about AirSpade and its benefits by contacting Andrew Knight on 0411 314 007, emailing sales@knightpneumatics.com.au, or logging on to knightpneumatics.com.au.

 

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