Landscape Contractor / Design Build Maintain

SEP 2017

LC/DBM provides landscape contractors with Educational, Imaginative and Practical information about their business, their employees, their machines and their projects.

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Page 48 of 71

Left A large redwood, not seen in the photo, caused structural damage to the con- crete of this pool in Sacramento, Calif. The root mapping team scanned the wall of the pool to determine the extent of the root growth and damage. September 2017 49 Silver Spring, Maryland, has developed special software called TBA™ (root analy - sis software) which is automated. At this time, the software cannot iden - tify or display the many different sizes of roots the radar encounters in the soil profile (this important feature continues to be in development, but is near comple - tion). The use of two different antennas has helped relieve this problem. A 900 MHz antenna emits high fre - quency radio signals that will penetrate the soil to a depth of a little more than three feet. As it does this, it will begin targeting roots that are a quarter inch in diameter or greater. The use of a 400 MHz antenna does the same but produces a lower frequency that will identify larger diameter, struc - tural roots. This antenna begins targeting roots that are one inch in diameter and greater. It has a depth range to twelve feet. Because of its depth capa - bilities, this really is the antenna of choice when it comes to, say, the construction of a basement or deep trenching. The utilization of these two pieces of equipment provides more information to the arborist on root size while the software continues development. One of the advantages of map - ping roots with GPR involves the method this technology uses to lo - cate them below ground. Healthy roots have a strong reflection; compromised roots produce a weak reflection. Roots that have been sev- ered or are dead (lacking moisture) have no reflection and will not be displayed in your final analysis results. At times, the area being scanned can pose a problem. Some soils can be com - posed of buried fill materials of all dif- ferent kinds. When this area is scanned, the radar signal will travel through the soil with no problems, until it encounters the fill material, then the data becomes unreliable at the lower level containing the fill. So at times we really don't know what conditions we are dealing with that could affect data collection until they are encountered. So when you are called upon to inspect concrete damage, your first thoughts may bring you to think, are these cracks from tree roots or is this just normal ground movement and settling. Yes, you won't know until you are able to look beyond what is visible. LC DBM (This article was edited to fit in the space allotted. The full article can be read here, - search/article-a.php?number=29543 ) Above The arborist seen here is scanning and mapping roots over a mo- saic stone driveway. This was part of a tree protection project that involved preserving this historic 100-year-old Moreton Bay Fig in preparation for future construction. Top, Right When root damage is suspected underneath the foundation of a home, excavation is not an option unless it is absolutely necessary. In this in- stance, the roots of an oak tree located under the home can be easily mapped without any excavation or damage to the home. Right TreeRadar Inc., has developed special software called TBA™. For in- creased accuracy in distinguishing root size, the arborist recommends the use of two antennas. Root data is collected from the field and is processed through this software to produce root mapping images.

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