Technical Applications Bulletin Use of Compressed Air-powered Excavation for Arboricultural Site Works
AirSpade® Technical Applications Bulletin Use of Compressed Air-powered Excavation for Arboricultural Site Works contributing authors Kelby Fite, Ph.D Dr. Thomas Smiley Richard N. Sweet Thomas C. Tremblay Joseph Wahler specifications Vincent P. Rico editor Terence J.
AirSpade® Technical Applications Bulletin Use of compressed air-powered excavation for arboricultural site works. September, 2016 contributing authors Kelby Fite, Ph.D Dr. Tom Smiley Richard N. Sweet Thomas C. Tremblay Joseph Wahler Vincent P. Rico, specifications Terence J. Fitzpatrick, editor With construction master specifications by Vincent P. Rico, of Rico Associates, and standard construction detail drawings by Stephen Stimson Associates available online through Guardair Corporation at www.airspade.
Table of Contents INTRODUCTION 03 Arboricultural Research and Practice by Dr. Tom Smiley and Kelby Fite 05 AirSpade Innovations, Techniques, Technologies by Richard N. Sweet and Thomas C.
Heritage tree preservation at the Massachusetts Institute of Technology: Successful tree preserva-tion requires collaboration with landscape architects, arborists, consultants, utilities, and contractors. The work shown here at M.I.T. utilized air-spading techniques and 2 AirSpade Technical Applications Bulletin placed the project arborist from Bartlett Tree Experts in an integral role in the design process and throughout construction. (Image courtesy of Stephen Stimson Associates.
Introduction by Terence J. Fitzpatrick, ASLA It’s fair to say that we value our trees a little more than we used to. Nowhere is this more true than in cities where the desire for human comfort and enjoyment align with the imperatives of economic, environmental, and social sustainability. Increasingly, people are turning to cities as places to live and interact, grow, learn, and find inspiration.
In their essay, Dr. Tom Smiley and Kelby Fite, Ph.D., provide insight into their research and development of practical applications using the AirSpade for over two decades at Bartlett Tree Research Laboratories. This work has contributed immensely to the industry at large and continues through arboricultural education programs and in supporting the growth of air-spading as it continues to become more readily available and acknowledged as a valuable professional service. Next, Thomas C.
Arboricultural Research and Practice Key findings, techniques, and practical application developed from Bartlett Tree Research Laboratories by Dr. Tom Smiley and Kelby Fite The AirSpade is a unique tool in the arboriculture industry. Shortly after its introduction to the industry in the 1990’s, we started using it here at the Bartlett Tree Research Laboratories to address a number of issues that affect tree health.
Air Excavation Technologies Research and Development in an Emerging Industry by Thomas C. Tremblay and Richard N. Sweet A BRIEF HISTORY OF AIR EXCAVATION The use of compressed air for excavation, as an alternative to mechanical or manual methods, began in the 1960’s among utility companies interested in reducing costs associated with underground pipe repair. Pneumatic excavation proved to be a reliable way to safely uncover utility lines without damage.
AirSpade® manufactured by Guardair Corporation an integral role in developing this research in collaboration with F.A. Bartlett Tree Expert Company. This type of collaborative research has advanced air-spading techniques and applications, and has also influenced the design of the AirSpade tool. TECHNOLOGICAL RESEARCH AND DEVELOPMENT The keys to effective and safe air excavation are (1) the design of the air output nozzle, (2) human factors, and (3) safety features that must be incorporated into the tool.
HUMAN FACTORS AND SAFETY In addition to the Supersonic Nozzle, a properly designed air excavation tool must incorporate ergonomic features, be easy to use, and, above all, safe. Compressed air is a powerful and potentially dangerous utility, so the tool must be properly engineered to handle air flow at Mach 2 as well as air pressures as high as 200 psi. Also, air excavation is often performed in close proximity to underground electric utility lines, so protection from high voltages is essential.
Anticipate and React Landscape Architectural Practice and New Opportunities for Tree Preservation by Joe Wahler, Landscape Architect, RLA, ASLA Principal, Stephen Stimson Associates Our goal for every project is to anticipate potential issues and establish procedures with our collaborators (client, contractor, consulting professionals, plant nursery, and maintenance) that result in long-term success.
Goat Clearing: At Parks and People, goats were brought to clear the overgrown site without causing damage to the numerous large specimen trees throughout the wooded lot. (Photo by Meredith Cohn from the Baltimore Sun, copyright, 2009.) Tree Survey: Parks and People’s arborist worked with local youths to survey the overgrown forest, including many of the largest trees in the area, and to help develop a vision for the design and protection of the site and its existing resources.
Parks and People, Baltimore: The site seen here, still in construction, has many large trees that define the experience of the site and its value to the community (photo courtesy of Ziger/Snead, LLC., architects). POST–COMPLETION REMEDY The built landscape is never perfect, and avoidable problems have a way of compounding when they evade detection. We’ve been reminded of this reality from time to time through valuable although difficult learning experiences.
Harvard Divinity School, Rockefeller Hall: Clients and decision makers are increasingly aware of the social and economic benefits of mature trees in their landscape. This combined with advanced techniques involving air-spading allow the tools to preserve trees 12 AirSpade Technical Applications Bulletin that, in the past, would have been considered economically infeasible or impossible to integrate into the constraints of a construction project. (Image courtesy of Stephen Stimson Associates.
Cambridge Residence: The beech hedge shown prior to initial planting. Despite proper planting, the plants subsided, resulting in their root crown being too low, and the hedgerow soil poorly drained. Root crown excavation and drainage cores were the remedy implemented by the project arborist, and the trees have done very well ever since. Cambridge Residence: The beech hedge was planted to enclose a generous lawn and private garden space.
Planting Beds Shallow / Heaving Roots This sympton of anaerobic and/or limited soil volume is also damaging to pavement. Using AirSpade, a trained arborist can safely excavate the root system to perform root pruning, train or lower roots, and oversee the replacement of a pavement system. Applications with AirSpade such as vertical mulching and radial trenching allow limited disturbance when working in planting areas.
Common Soil Issues TOPSOIL ‘A’ HORIZON Certified arborists and other experts should identify issues affecting tree health including soil composition, compaction, aeration, and hydrology. Savvy application of AirSpade will maximize health benefits, safety, and flexibility in responding to these vital issues. Shallow Root Growth AirSpade operations such as vertical mulching can increase the viable soil depth.
General Site Provisions Proper site preparation, tree protection, and safety procedures are vital to the success of any project using an AirSpade. Overall tree health is crucial prior to the use of an AirSpade. The project team, including a certified arborist, should evaluate trees to be impacted and ensure proper watering and health-care well in advance of the scheduled work.
NOTES: 1. THE CRITICAL ROOT ZONE (CRZ) SHALL BE ESTABLISHED BY THE ARBORIST AND LANDSCAPE ARCHITECT. THE CRZ MAY BE WITHIN OR OUTSIDE OF THE TREE'S DRIPLINE DEPENDING ON THE PROJECT GOALS, CURRENT AND FUTURE PROJECTION OF THE TREE'S ROOT PROLIFERATION, AND OTHER SITE CONDITIONS. THE CRZ SHALL BE PROTECTED AND MAINTAINED BY ALL CONTRACTORS THROUGHOUT CONSTRUCTION. ANY WORK WITHIN THE CRITICAL ROOT ZONE SHALL BE OVERSEEN BY THE ARBORIST. 2. UNLESS OTHERWISE SPECIFIED, TREE PROTECTION FENCE SHALL BE 6' HT.
Air Tilling (Root Invigoration) 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 (lack of organic matter, nutrients, beneficial organisms, or aeration) are ideal candidates for air tilling.
NOTES: 1. PROPOSED DEPTH OF AERATION AND OPTIONAL SOIL AMENDMENTS TO BE DETERMINED BY LANDSCAPE ARCHITECT, CERTIFIED ARBORIST, AND SOIL SCIENTIST BASED ON INITIAL SITE INVESTIGATION AND BASED ON INDIVIDUAL SITE CONDITIONS AND TREE HEALTH CARE NEEDS. 2. ALL TURF WITHIN AREA TO BE AIR-SPADED SHOULD BE REMOVED IN ADVANCE USING AN HERBICIDAL TREATMENT. USE AIRSPADE TO BARE-ROOT IMPACTED PLANTINGS DURING SOIL AERATION.
Radial Trenching Radial trenching with AirSpade is done to modify soil composition, improve aeration, and encourage root growth to moderate depths (typically 10”-12” 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.
X. NOTES: 1. SPACING, WIDTH AND DEPTH OF RADIAL TRENCHING TO BE DETERMINED BY L.A. AND/OR CERTIFIED ARBORIST BASED ON INITIAL SITE INVESTIGATION. SPECIFIED TRENCHING AND SOIL AUGMENTATION SHOULD BE BASED ON INDIVIDUAL SITE CONDITIONS AND TREE HEALTH CARE NEEDS. ACTUAL LOCATION OF TRENCHING MAY BE ADJUSTED SLIGHTLY BASED ON FIELD CONDITIONS. TRENCHES SHOULD OCCUR BETWEEN ROOTS AND AVOID FOLLOWING PRIMARY LEADERS. 10' MA TRENCH W/ AIRSPADE, TYP. 2.
Vertical Mulching Vertical mulching with 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, thereby improving the tree’s stability and volume of viable growing medium.
NOTES: 1. DEPTH AND SPACING OF BORE HOLES TO BE DETERMINED BY LANDSCAPE ARCHITECT AND/OR CERTIFIED ARBORIST BASED ON INITIAL SITE INVESTIGATION. SPECIFIED BORE HOLE DEPTH MAY RANGE FROM 18" TO 36" AND SHOULD BE SPECIFIED BASED ON INDIVIDUAL SITE CONDITIONS AND TREE HEALTH CARE NEEDS. 2 USE AIRSPADE TO BARE-ROOT IMPACTED PLANTINGS DURING SOIL AERATION. STOCKPILE, PROTECT, AND WATER PLANTS AS NECESSARY, AND ENSURE PROPER REPLANTING OR REPLACEMENT AT COMPLETION OF WORK.
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.
NOTES: 1. PROPOSED FINISHED GRADE TO BE DETERMINED BY LANDSCAPE ARCHITECT AND/OR CERTIFIED ARBORIST BASED ON INITIAL SITE INVESTIGATION AND BASED ON INDIVIDUAL SITE CONDITIONS AND TREE HEALTH CARE NEEDS. 2. ROOT PRUNING TO BE DONE BY HAND ONLY AND BY CERTIFIED ARBORIST. 3. ALL WORK TO BE DONE UNDER THE SUPERVISION OF CERTIFIED ARBORIST OR APPROVED CONTRACTOR. ENSURE THAT TREES ARE IN GOOD HEALTH AND NOT EXPERIENCING UNUSUAL STRESS PRIOR TO COMMENCING WORK. 4.
Root Pruning Construction or maintenance work that makes intrusions into a tree’s root zone will benefit from use of an AirSpade. Air-spading 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 air-spading and root pruning.
NOTES: 1. HAND PRUNE ROOTS ONLY BY CERTIFIED ARBORIST. DO NOT SHEAR ROOTS. 2. COVER ROOTS AND PROVIDE SUPPLEMENTAL WATER AS NECESSARY. IF LARGE ROOTS OR A LARGE PERCENTAGE OF ROOTS ARE REMOVED, EXTENDED RECOVERY PERIOD MAY BE NECESSARY. 6"-12" MIN. TO PRIMARY ROOTS 3. ALL WORK TO BE DONE UNDER THE SUPERVISION OF CERTIFIED ARBORIST OR APPROVED CONTRACTOR. ENSURE THAT TREES ARE IN GOOD HEALTH AND NOT EXPERIENCING UNUSUAL STRESS PRIOR TO COMMENCING WORK. 4.
Bare Rooting and Transplanting Bare rooting is a procedure used to relocate or remove soil around existing trees. Use of an AirSpade for bare rooting is the best way to minimize damage to the tree’s root system and the most efficient technique available. Bare rooting with an AirSpade can also be applied to perennial, shrub, and groundcover plantings. This is a preferred method of transplanting plant material because of its efficiency and ability to preserve fine root systems.
NOTES: 1. HAND PRUNE ROOTS ONLY BY CERTIFIED ARBORIST. DO NOT SHEAR ROOTS. 2. COVER BARE ROOTS AND PROVIDE SUPPLEMENTAL WATER AS NECESSARY. IF LARGE ROOTS OR A LARGE PERCENTAGE OF ROOTS ARE REMOVED, EXTENDED RECOVERY PERIOD MAY BE NECESSARY. PRIMARY ROOT, TYP. 3. ALL WORK TO BE DONE UNDER THE SUPERVISION OF CERTIFIED ARBORIST OR APPROVED CONTRACTOR. ENSURE THAT TREES ARE IN GOOD HEALTH AND NOT EXPERIENCING UNUSUAL STRESS PRIOR TO COMMENCING WORK. TRANSPLANT ROOT ZONE 4.
Urban Tree Soil Replacement Soil science and planting technologies for urban trees have undergone tremendous advancement in the last several years. For example, engineered structural soils can resist compaction from traffic or bear the weight of pavement or structures while also offering aeration and nutrients deep into the soil profile.
NOTES: 1. LIMIT DISTURBANCE OF EXISTING SOIL BASED ON EXISTING SOIL CONDITIONS AND FOUND DISPERSION OF TREE ROOTS. ALL DIGGING AND SOIL REPLACEMENT OR AUGMENTATION TO BE DONE UNDER THE SUPERVISION OF CERTIFIED ARBORIST. 2. ALL WORK TO BE DONE UNDER THE SUPERVISION OF CERTIFIED ARBORIST OR APPROVED CONTRACTOR. ENSURE THAT TREES ARE IN GOOD HEALTH AND NOT EXPERIENCING UNUSUAL STRESS PRIOR TO COMMENCING WORK. 3. PROTECT TREE AND TREE ROOTS THROUGHOUT CONSTRUCTION.
APPENDIX 32 AirSpade Technical Applications Bulletin
Appendix A: Soil Amendments Table 2. Potential uses and limitations of typical soil amendments for urban trees.
Appendix B: Construction Specifications SECTION 312317 4. Remove and break up soils around existing trees to facilitate root pruning. 5. Remove and break up soils around existing trees to locate tree roots. 6. Remove and break up soils around existing trees to accommodate proposed site construction. 7. Root collar (crown) excavation (RCX) to expose the lower trunk and buttress roots of the designated trees and shrubs. 8.
1.04 DEFINITIONS A. Arborist: An individual engaged in the profession of arboriculture who, through experience, education, and related training, possesses the competence to provide for or supervise the management of trees and other woody ornamentals. B. Dripline: An imaginary line defined by the branch spread. C. Critical rootzone (CRZ): The minimum volume of roots necessary for the maintenance of tree health and stability, typically determined by measuring the tree diameter 4.5 ft.
F. Conduct a Tree Root Zone Investigation and evaluate the crown/foliage rating of each tree. Submit a health assessment for each tree to undergo specialized soil exacavation operations, prepared by a certified arborist, indicating that each tree is healthy enough to withstand the proposed AirSpade operation and anticipated soil and/or root system disturbance. 1. Submit digital photos documenting tree conditions and illustrating the findings of the Tree Root Zone Investigation. Refer to Paragraph 3.05. 1.
B. Site monitoring shall be the responsibility of a Certifed Arborist. Any damage to existing trees shall be immediately reported to the architect. If any tree has been damaged, work shall be halted and reasons for damage assessed. No work shall commence until contractor has submitted a plan for prevention of further tree damage and plan has been approved in writing by landscape architect. 1.09 A.
3.02 SOIL PREPARATION 3. Defining the area to be excavated – mark the soil surface of the area to be inspected and define the depth of inspection/soil removal. 4. After inspection, define how the space is treated; i.e., fill it in with the same soil, new soil, or leave open; mulch, sod, or seed on surface. 5. Define aftercare, e.g., soil moisture sensors, irrigation level, or frequency. A.
B. Spray paint lines on the ground to indicate trench locations. C. When the tree’s excavated root zone will remain exposed for several days or more, protect and cover roots (for example with soil, mulch, or burlap cloth) and provide supplemental water as required. C. Create trenches to a specific depth (typically 10 to 12 in. deep) depending on individual site needs and determined health of trees. 3.10 D.
Glossary Aeration. Describes the ability of air to transfer through the soil, and the availability of oxygen to a plant’s root system. Also used to refer to several techniques used to loosen or penetrate compacted or poorly drained saturated soils. Directional root pruning. Cutting root branches that are growing in the desired direction. Air-spading. Refers to any specialized soil excavation technique utilizing a supersonic compressed air-powered tool. Fibrous root.
resistant, and relatively low in nutrients. Other common mulches are made from composted organic matter such as leaves or pine bark. maintain healthy soil ecology and sustained tree nutrient uptake and root growth. Permeability. The ability of water to pass through soil. Permeability is commonly impacted by soil composition, gradation, and compaction. Specialized Root Zone and Soil Excavation Plan. Indicating the extent of soils to be air-spaded.
Further Reading Online Resources ANSI A300 Support Systems Standard (Part 2). “Best Manangement Practices Soil Management for Urban Trees.” International Society of Arboriculture (ISA), 2014. AirSpade “Applications: Arboriculture/Horticulture,” including master specifications: https://www.airspade.com/applications/markets/ arboriculture-horticulture ANSI A300 Support Systems Standard (Part 3). “Tree, Shrub, and Other Woody Plant Maintenance – Standard Practices (Supplemental Support Systems).
Contributors and Bios Bartlett Tree Research Laboratories Kelby Fite, contributing author V.P. Research & Director at Bartlett Tree Research Laboratories Kelby has been a member of the Bartlett Tree Research Laboratories team for fourteen years, beginning as a Plant Protection Specialist. In his current position as Director of Research, his key area of responsibility is research and public education in shade tree management and arboriculture, with emphasis on urban soils and integrated pest management.
AirSpade Technical Applications Bulletin Guardair Corporation Bartlett Tree Research Laboratories Stephen Stimson Associates | Landscape Architects This booklet is available to download as a PDF, along with CAD details online at: www.airspade.com/guide Division of Guardair Corporation 47 Veterans Drive • Chicopee, MA 01022-1062 Toll-Free: 800-482-7324 | Local: 413-594-4400 | Fax: 413-594-4884 Email: info@airspade.com • airspade.
