Tree Roots Lifting up Sidewalk?

Posted on August 11, 2020 by landscapeexpert

Who is Better Qualified to Opine on Root Damage, Civil Engineer or Certified Arborist?

I was retained by a defendant attorney to determine whether her client’s tree was responsible for lifting the adjacent civil sidewalk that resulted in a plaintiff trip and fall lawsuit. Based on the photographs and tree species, White mulberry (Morus alba), I was fairly certain her client’s tree was responsible for the sidewalk damage.

The attorney retained me and requested a site inspection and tree root assessment. I trenched adjacent to the sidewalk and within a short time, encountered a three-inch diameter root growing under the sidewalk. Further excavation revealed a network of two to four-inch diameter roots that had grown under the sidewalk, resulting in the tree roots lifting up the sidewalk panel, creating a hazardous condition resulting in a trip and fall accident.

I informed the attorney that tree roots lifting up the sidewalk, or root encroachment from her client’s tree resulted in the sidewalk damage, she said her civil engineer expert claimed it impossible for a tree root to lift a concrete sidewalk. I questioned the engineers knowledge and experience with trees, was the civil engineer a certified arborist or horticulturist?

Although the answer was no, she felt his qualification as a civil engineer was superior to my qualifications as a certified arborist, tree risk assessor qualified, registered consulting arborist and a college educated horticulturist. Her dilemma was having two experts who disagreed and she requested I alter my opinion.

I told the attorney altering my opinion to suit her needs was unethical, and I removed myself from the case.

What Causes Tree Roots To Lift up a Sidewalk?

The common myth is trees have tap roots that grow straight down into the soil. While this may occur in very deep, loam soils, the reality is most containerized nursery grown trees lose their tap root in the container. Once planted in our poor Southern California soils, when the tap root encounters physical soil obstructions, such as rock, clay or hardpan, the tap root divides and grows multiple roots around the obstacle, forming a fibrous root system. Tap root grows into fibrous root system.

Trees require a spreading root system to maintain structural stability. Trees dissipate energy generated during a storm or wind event by transmitting leaf, limb and trunk movement down to the roots. A spreading root system anchors the tree movement and dissipates the energy far more effectively than a single tap root system.

Most tree roots grow within the top 24-inches of the soil horizon. Roots in top 24″ of soil. Over time, structural tree roots (2-inch diameter and greater) growing within a shallow soil adjacent to sidewalks, footings, foundations, walls or othersub-surface infrastructure may cause damage.

Just as a twig grows into a branch, and then a limb, roots increase in length and circumference. Irrigation water, sewer or water service leaks increase subsoil moisture beneath sidewalks or garage slabs, creating a perfect environment for root growth.

Cracked garage slab

As the root circumference increased, it exerts pressure on the concrete slab or footing above the root. Depending on the species, root diameter might increase 1/8-1/4” annually.

Within five to eight years, a small feeder root may grow to one-inch in diameter or greater.

Ficus root cracked the garage slab

The root growth may be compared to the action of a hydraulic jack, as the circumference increases, the upward pressure on the sidewalk or slab may crack and or eventually cause tree roots to lift the sidewalk. Concrete lifting may often occur at an expansion joint between concrete panels

Sidewalk lifted at expansion joint

Root network beneath sidewalk.

Roots seek out soil moisture, they can and will grow under walls, footings and garage slabs. Roots are opportunistic, leaky plumbing, old cast iron sewer lateral or water services contribute to the soil moisture needed for roots to flourish.

Sewer lateral root damage

Roots may infiltrate pvc, abs and cast-iron pipe through even the smallest of cracks or holes.

Once inside, the roots expand in size and quantity, eventually completely clogging the utility.

If the tree crown has grown over a sidewalk or adjacent structure, it is a reasonable assumption structural roots (two-inch diameter and greater) have grown under the sidewalk, slab or footing.

Root growing under house footing

Planter areas confined by concrete pose one of the greatest risks for root damage. City sidewalks often incorporate small, square planters within the sidewalk easement.

Roots lifting water meter and sidewalks

Confined planters quickly fill with structural roots, as well as damaging girdling root. As the tree crown grows, so to do water absorbing feeder roots. Over time, root mass and size increases, structural roots may begin to grow beneath concrete improvement while seeking out moisture.

Leaking water meter, high soil moisture, confined growing space.

The tree pictured above and to the right had a leaky water meter adjacent to the small sidewalk planter. The leaky service provided idea soil moisture conditions for the roots to lift the water meter box, adjacent sidewalks and crack the curb and gutter.

Preventative measures to minimize root encroachment include a variety of root barrier methods. All root barrier systems work best when the tree is installed. Once roots have enlarged and matured, barrier mitigation is not successful.

In summary, our Southern California poor, shallow soils do not support deep tree tap root systems. Most trees grow fibrous spreading root systems. Structural roots emanating from the root collar extend to the edge of the tree crown, (drip line). Most structural roots growing beneath sidewalks range from two to four inches in diameter, lifting sidewalk panels on average one-two inches. Trees growing in confined planters or adjacent to concrete, utilities or foundations may develop structural roots capable of lifting, cracking or damaging adjacent improvements.

Dealing with legal issues due to tree roots lifting up a sidewalk?

Attorneys should select an expert based on the case criteria, not simply a title, license or certificate. Choose an expert most appropriate to address the cause of the problem and develop opinions based on sound, industry practices.

Trip, Slip and Fall Hazard: Hidden Depressions in Grade

Posted on May 19, 2020 by landscapeexpert

Successful landscapes require:

Proper grading, drainage and amended soil.
An automatic irrigation system achieving 100% head to head coverage.
Properly installed, high quality plant material.

Each of these functions may require a specific type component, installed at a specific height or location to reduce the potential of creating a site hazard that may result in an accident. In commercial applications, landscape plans usually include details and specifications dictating type of product and how it should be installed.

Many common landscape products may be improperly installed including:

Pop up heads may be incorrectly set to grade against a sidewalk.
Valve or drainage boxes set too high or low relative to finish grade.
Shrub head installed on a riser adjacent to concrete improvement.
Hidden, obscured depressions in grade due to substandard compaction, settlement and subsidence.
Drainage box set too low.

Improper product selection or substandard installation practices may appear obvious. A pop up sprinkler head set above the top of adjacent concrete sidewalk creates a trip hazard. A drainage structure set well below the turf grade creates a trip slip and fall hazard. Selecting and installing a spray head on a rigid riser next to a pedestrian sidewalk is a sub-standard industry practice that creates a trip and fall hazard.

Spray head on a riser next to a sidewalk creates a trip hazard.

Not all landscape hazards are visible. Turf areas may have grade depressions or holes that are hidden by overgrown turf grass. Depending on the cause and time period, turf grass may completely hide the depth, location and size of the depression or hole, creating a hidden hazard.

A depression, rut or hole may result from several factors. Repeated mowing on saturated turf may create ruts. Overwatering may cause irrigation or utility trench settlement. A dead tree removed from a turf area may result in a future depression if the grade is not properly backfilled and compacted.

A seven inch deep hole hidden by turf grass.

Bermuda grass is a fast horizontal spreading turf-grass used in parks and recreation facilities throughout the country. Unless regularly aerated and de-thatched, Bermuda grass in known to grow a thick layer of thatch. Over time, the thatch layer can increase the turf grade several inches above adjacent sidewalk and curbs.

The backfill in utility trenches installed across pre-existing turf may settle, creating a depression in the sub-grade. The photo depicts the edge of a trench cut across an asphalt driveway, across a turf area. The trench backfill eventually settled, creating a trench sub-grade depression hidden by the Bermuda grass.

Thatch, hidden depression and sanded turf.

The depression resulted in a trip and fall accident. After the accident, several hidden turf depressions were “sanded” to fill depressions to proper grade.

Not all landscape hazards are open and obvious. Even a perfectly installed landscape may develop hazardous conditions if not regularly inspected and maintained.

Irrigation systems should be monitored, inspected, tested and adjusted monthly. Turf should be trimmed around utility boxes and vaults regularly, aerated and de-thatched annually to maintain optimum performance and minimize grade changes. Drainage structures should be grade adjusted, repaired or replaced when damaged. Valve, electrical and junction boxes should be monitored for grade changes and adjusted as required. Bark mulch thickness should be monitored and supplemented annually to maintain proper coverage and grade.

In summary, a properly installed landscape is composed of several systems and components that require regular ongoing maintenance for optimum performance, efficiency and safety. Pro-active landscape maintenance may reduce potential hazards, resultant accidents and lawsuits. These actions demonstrates an Owner’s recognition of protecting the health and safety of the public, pedestrians, friends and family who may visit and use the site and may prove useful in a legal action.

Arborist Online Learning Opportunities in the Covid Era

Posted on May 12, 2020 by landscapeexpert

In a recent blog, I discussed using online media for a site online site inspection involving a Torrey pine tree root conflict with adjacent asphalt paving. That marked the first time I used an online media tool rather than being physically present at the site. My client and I used Facetime to conduct the real time inspection.

As the restrictions ease, I believe the use of online media such as Zoom, Hangouts, Facetime etc will increase. I have already presented this concept to a legal client in Northern California concerning an irrigation inspection. Do I really need to fly from San Diego to San Francisco, rent a car, drive to the site, observe irrigation defects, then reverse the process returning home or, can I watch the inspection over the web? The level of scrutiny required depends on the individual case.

A slide from Dr. Smiley’s presentation

Like so many other industries, the tree industry is rapidly adapting to the new Covid – 19 reality. Today, I attended an online Zoom seminar titled Sidewalks, Urban Plazas and Tree Roots. This seminar was presented through the ISA Southern Extension. I believe it was originally going to be part of a “normal” ISA Southern Association Annual meeting that was cancelled due to Covid.

The online presentation occurred through Zoom with over 1000 arborists throughout the U.S. and other countries attending. The topic concerned tree roots damaging sidewalks, presented by Dr. Thomas Smiley. Once a few technical glitches were adjusted, the presentation was almost identical to what I had experienced attending many seminars.

The slides presented alongside the audio streaming from Dr. Smiley was easy to view. I became immersed in the content and found myself taking pics of some of the slides. The topic provided test data results using different techniques designed to reduce root intrusion beneath sidewalks.

Incorporating root growth inhibitor practices

The presentation lasted an hour, same amount of time I’m accustomed to when attending a seminar. Although I already knew a great deal about the topic, I still came away with new information for use in my practice, including a great specification detail incorporating multiple root growth inhibitor practices that may reduce sidewalk damage due to roots.

In the past month, I’ve been able to continue my consulting practice from my home office. I’ll continue to utilize more online media tools, whether for learning, conducting site inspection work, and client meetings. I believe these new opportunities are one of the (few) beneficial results from the Covid-19 virus.

I recently provided a client with a proposal to develop landscape maintenance specifications for commercial properties located in several different climatic regions. The proposal did not include any site visits. All data collection would occur online through various means. Using online data collection versus conducting multiple site visits saved the client thousands of dollars.

I’m looking forward to these new opportunities utilizing online media sources as potential replacement for physical presence. Hopefully it will prove an efficient, effective, cost saving technique without sacrificing product accuracy.

Online Site Inspections with Corona Virus: A New Paradigm?

Posted on April 24, 2020 by landscapeexpert

The corona virus and resulting stay at home order has prevented me from scheduling or attending site inspections. I require site inspection for most forms of consulting work, including as a consulting arborist or expert witness.

Tree failures, health and risk assessment
Tree inventories
Tree and nursery appraisals
Tree roots and infrastructure damage.
Landscape appurtenances creating trip and fall hazard.
Obscured landscape hazards, grade changes
Irrigation operation, maintenance issues

A client wanted me to attend and observe asphalt paving taking place adjacent to an 80 year old Torrey Pine. I had previously consulted on preserving this tree during construction on an adjacent property. The client was repaving his driveway on the alley, the pine is right on the edge of the paving.

Due to California stay at home orders, I informed the client I could not be present to observe the paving to make recommendations, so we used the Facetime app and did an online site observation whereby I watched in real time as the work was being performed. I was able to give the client recommendations in real time.

Moistened towel protect surface roots

He was concerned about root damage, and rightly so. Some of large buttress roots would be impacted by the paving. Instead of cutting, I recommended covering the roots with wet towels, fabric etc, then placing moistened sand base, then pave over the roots.

Moistened sand placed over protected roots

As terrible as it is, the corona virus has created many new ways for industries to re-invent how they do their business. This was the first time I have attempted on online site inspection and it worked! This may not be applicable for the types of investigations I perform, but there is a great new tool I can use for certain types of investigations during stay at home and even beyond.

Asphalt paving over protected roots

The financial savings for the client are obvious. Travel costs for me to travel to Los Angeles, Orange or Inland Empire typically range from $500 to $1000 or more if hotel stay is required.

Not all inspections can be performed remotely. Forensic investigations that require measurements, excavations, sampling, testing etc may not be applicable.

Since this is new to me, it will take some real time client cases for me to determine how and when I can utilize this new tool.

Joshua Tree Extinction by End of Century?

Posted on April 14, 2020 by landscapeexpert

I just read an article in the Los Angeles Times about a potential listing of the Joshua tree as an endangered species. The western Joshua tree, Yucca brevifolia, is one of two genetically distinct species that occur in California. It range extends from Joshua Tree national park westward along the northern slope of the San Bernardino and San Gabriel mountains, northward along the eastern flank of the Sierra Nevada and eastward to Death Valley.

Approximately 40% of the western tree range is on private land, the eastern range is centered in the Mojave National Preserve and eastward into Nevada.

After decades of climate change, development, drought and wildfires, the species is facing a rapidly increased the risk of extinction. State Department of Fish and Wildlife Commission will decide in June whether to accept the department’s recommendation to declare the tree an endangered.

As usual, there are two sides to the issue. Conservationists see this as a triumph of state environmental law while critics claim it as a misguided overreach because Joshua trees are already protected under many city and county ordinances and within the 800,000 acre national park.

Environmentalists argue existing state and local ordinances are largely inadequate at protecting species habitat loss, the endangered species listing will finally provide a statewide protection for the species, including requiring wildlife managers devise a recovery plant for the species, which could limit development in SoCal real estate.

The Joshua tree exists in high desert communities such as Yucca Valley or Hesperia, communities with lower average median household incomes. They are concerned the listing would impose additional burdens to real estate development, making it tougher to improve their property or curtail new development in their communities.

However, researchers warn time is running out. The tree’s range is contracting at lower elevations, its reproduction has come to a halt. Trees are failing to reproduce at lower, hotter elevations. They could become extinct in California by the end of the century!

This would be a terrible outcome for a truly incredible species. This remarkable species deserves protection. I believe this tree, in its own way is as majestic in its high desert setting as the coast redwood. These are species distinct to our California heritage. The Joshua tree deserves protection for our future generations to enjoy, marvel and be uplifted by this unique species.

Download a pdf of the article here: Los Angeles Times – eNewspaper

The Benefits of the ANSI A300 Tree Care Standards for Tree Related Lawsuits

Posted on January 18, 2018 by landscapeexpert

Guy + Chainsaw – Tree = Potential Lawsuit vs
ANSI A300 Tree Care Performance Standards

Does he know what he is doing?

Background

Tree care professionals contracting for services are frequently members of the Tree Care Industry Association, (TCIA). The International Society of Arboriculture, (ISA), administers various types of arborist certification programs, including certified arborist or certified tree worker climber. The American Society of Consulting Arborist offers arborists training and testing to become a registered consulting arborist, (RCA). These associations provide industry standards and best management practices for members to adopt into in their own practice.

Personal protective clothing, ropes, saddle etc.

In California, C-27 landscape contractors and D-49 tree service contractors are licensed by the state, both can legally perform tree care service. Prior to 1991, various industry associations, contractors and practitioners followed their own standards for tree care.

The industry recognized the need for a standardized, scientific approach and agreed to develop an official American National Standard, resulting in the American National Standards Institute (ANSI) A300 Tree Shrub, and Other Woody Plant Management Operations – Standard Practices.

They are voluntary industry consensus standards developed by TCIA and written by the Accredited Standards Committee (ASC) A300, whose mission is to develop consensus performance standards based on current research and sound practices for writing specifications to manage trees, shrubs, and other woody plants.

The ISA and ASCA are members of the ASC and their member practices should conform to the ANSI A300 tree care performance standards. The standards “apply to professionals who provide for, or supervise the management of trees, shrubs, and other woodsy landscape plants. Intended users include businesses, government agencies, property owners, property managers and utilities.” Many municipalities have adopted the ANSI A300 performance standards as part of their tree and landscape maintenance ordinance. The A300 standards are separated into 10 parts based on the tree care practice.

ANSI A300 Performance Standards for Legal Conflict Support

Arboriculture professionals adhere to the ANSI A300 performance standards for developing specifications for tree care. Gardeners, landscapers, designers, and handy men are not certified arborists and rarely have knowledge of industry standards. Even licensed landscape architects, civil engineers, general and landscape contractors may not be familiar with or have knowledge of the A300 standards. Ignorance of the standards is not a legal excuse for violating or ingnoring the standards.

The standards are separated into ten different parts. Through case experience, I have found three of the ANSI A300 standards applicable for plaintiff or defendant tree related legal actions. In conflicts I’ve been involved with, the civil engineer, landscape architects, general contractor, landscape and sub-contractors and even licensed tree care companies were not aware of the A300 standards. In some instances, industry professionals were aware of the standards but failed to adhere to the them.

Without proper planning and management, construction and development projects adjacent to existing trees commonly damage tree roots, trunks and limbs, increasing the risk of a potential tree failure and resultant lawsuit. ANSI A300 (Part 5) Standard Practices (Management of Trees and Shrubs During Site Planning, Site Development, and Construction) is the recognized industry standard for managing trees during construction and is the focus of this discussion.

The A300 Part 5 Performance Standard is intended for use for industry professionals, including all levels of government agencies, private entities including commercial, industrial and residential property owners and managers, engineers, architects and utilities for developing written specifications. The standards apply to any person or entity engaged in the management of trees, shrubs or other woody plants.

ANSI A300 Part 5 standard

Without specifications for tree protection during construction and development, tree injuries occur. Depending on the severity of the injury, the defect may degrade the structural integrity of the tree. Over time, the injury may continue to decay, increasing the risk of failure and resultant damage to people and or property. The reason for the standard is to assess the level of risk and to provide information for risk mitigation.

Civil engineers, landscape architects and other professionals responsible for developing plans and specifications should be aware of the A300 standards. These professionals may not have the tree knowledge expertise, which is why the standard refers professionals to use a certified arborist qualified in tree management during site planning, development and construction.

The standard discusses implementation procedures that should be designed by a professional arborist including:
• Tree management plans in compliance with applicable ordinances and standards.
• Decision making should be based on the knowledge of health and safety of the tree resources present.
• Prime consultant and contractor should involve the arborist in the initial planning phases.
• Arborist site monitoring during construction should be specified to ensure compliance with plan requirement.
• Monitoring specifications should address demolition, grading, vertical construction, walks and pathways, playgrounds, excavations, trenching, drainage systems, and landscape.

For safety, the standard requires only arborists familiar with the standards, practices and hazards of arboriculture shall perform tree management. One of the objectives of the standard it to avoid damaging trees during construction; including damage caused by physical contact, grade changes and soil compaction. To achieve the defined objectives on any project, the arborist should be involved in the management of trees during all five phases of development including:
• Planning
• Design
• Pre-construction
• Construction
• Post-construction

Development and construction projects are complex, requiring planning and coordination among project shareholders. The prime consultant and or contractor should maintain arborist involvement throughout the various phases of the project in conjunction with the arborist developing specifications, resource assessment, conservation plans, monitoring and recommendations. The TCIA website has an exhibit of a Tree management plan flow chart defining what should occur during the development phases, arborist responsibility and development activity.

How the A300 Standard Applies in a Legal Context

The standard applies to all design and planning professionals such as civil engineers and landscape architects. These firms usually work as prime consultants and are responsible for producing the plans and specifications for development projects. They are responsible for knowing and adhering to the A300 performance standards. The same applies to prime contractors and their sub-contractors, and other project stakeholders.

Failing adherence to the A300 standards renders prime consultant(s), general and sub-consultants potentially liable if a tree related accident occurs. I used the A300 standard in a case involving a tree limb that fell from a tree onto an adjacent tot-lot.

A city decided to build a park within a former old growth forest. A civil engineer and landscape architect developed plans and specifications, including a grading plan with notes and a detail for tree protection. The general contractor, grading, and recreation equipment sub-contractors constructed the park. The design included a tot-lot with children play equipment built where trees were removed, with old, construction damaged trees remaining left intact at the edge of the tot-lot.

A few days after the park opened, a tree limb dropped onto the tot-lot, striking and killing a young child seated on a piece of play equipment. The parents sued the city, the design consultants and all the contractors because the defendants did not observe the city tree ordinance. The city ordinance adopted the A300 tree care standards as part of their tree ordinance, which the defendants ignored, arguing the standard did not apply to their trade(s). After extensive deposition testimony, using the standards in support of the Plaintiffs (parents of the deceased child), all the defendants settled rather than proceeding with a trial.

In another case, a property owner agreed to allow a guy to prune a tree. The guy claimed to have forestry experience. He had a rope tied around a limb that he cut just as a neighbor walked out of their house. The limb dropped, rebounded at the end of the rope causing it to swing and strike the neighbor in the face. In the resulting lawsuit, the A300 standards were used to support the plaintiff complaint with a resultant settlement from the insurer.

The A300 standards apply to tree care companies, certified and consulting arborists. Different standards may apply depending on the case. For example, A300 (Part 9), Tree Risk Assessment A. Tree Failure, provides performance standards for tree risk assessment and guidelines for establishing written specification and best management practices, (BMP).

As a certified and registered consulting arborist, tree risk assessment inspections and reports are consulting services I provide, I’ve incorporated this and other standards into my practice. Tree care contractors might find other standards, such A300 (Part 1) Pruning, Part 5 (previously discussed) and Part 9 particularly applicable to their business.

In conclusion, the ANSI A300 Tree, Shrub, and Other Woody Plant Management Performance Standards are a powerful tool that may benefit a plaintiff or defendant involved in a tree related accident. The standards are broad reaching in scope and application to a wide variety of construction and development professionals. Attorneys and insures should consider the potential application of A300 performance standards in tree related cases.

Spring Madness

Posted on April 3, 2017 by landscapeexpert

The beauty of spring is all around us, take a moment to enjoy it. Take a walk through any of our coastal canyons, parks and open spaces. You’ll be rewarded!

Not a field of poppies but still…

Wow

Get out there!

One of the Best Flowering Trees!

Posted on March 30, 2017 by landscapeexpert

Back in my college days at Cal Poly Pomona, I took several plant identification courses as part of the educational requirements for Ornamental Horticulture. Two trees from the same genus always stood out for their outstanding floral display and landscape use. Back then, the genus was called Tabebuia, since changed to Handroanthus. The two useful landscape species are Handroanthus impetiginosa,(Pink trumpet tree) and H. chrysotrichus, (Golden trumpet tree).

The Pink trumpet tree in full bloom

While taking a walk, I came across a beautiful pink trumpet tree in full bloom. I then started noticing a few other trumpet trees scattered about the neighborhoods in North Park. I’m not to sure why, but in my view, this species is an under utilized ornamental landscape tree. Perhaps due to a slow growth rate, medium appetite for water or its deciduous nature, the species is not heavily promoted by the nursery industry. But it has many beneficial characteristics making it a useful ornamental landscape tree.

The pink trumpet tree requires full sunlight to part shade and grows to approximately 25-feet in height in Southern California. The non-aggressive rooting system makes it a good choice for use in smaller confined planter areas such as a parkway strip. It performs well in the urban environment. Like most trees, it prefers well drained fertile soils however I see this tree flourishing under less than ideal conditions. No noted pests or disease, hardy to 24º F, damaged below 18º F. After spring flowering, it grows a green to brown colored pod.

A close relative to the pink trumpet tree but faster growing. By M.Ritter, W. Mark, J. Reimer, C. Stubler

Unlike the pink trumpet tree, the closely relate golden trumpet tree is a more rapid, larger growing tree. It too is deciduous, and like the pink trumpet, it flowers in the spring with an impressive display of brilliant, fragrant yellow trumpet flowers.

This tree grows to a larger size than the pink trumpet, up to 50-feet tall and similar width. It has a spreading, low canopy that matures into a broad, round-headed or vase shaped crown. It prefers full sun to part shade.

Branch strength is rated as medium to somewhat weak and root growth is more aggressive than the pink trumpet. Unlike the pink trumpet, the golden trumpet tree should not be used in a confined planter are.

Both these trees perform well in our mediterranean climate and their different growth characteristics allow for varied use, one in more confined areas, the other requires more room to grow. Once established, both are relatively drought tolerant.

Hope you find this helpful, let me know if you have any questions!

Worried About Your Tree?

Posted on March 23, 2017 by landscapeexpert

We have gone from record drought to record amounts of snow and rain throughout California. While the winter storms have wreaked havoc on our infra-structure (Oroville dam spillway, flooding in San Jose, etc, they have been a blessing for drought starved trees throughout the west. Years of inadequate rainfall reduced soil moisture leading to an incredible dieback of trees numbering over tens of millions within the state.

The urban environment creates stresses not normally encountered in the wild. In cities and suburbs, trees contend with confined planter area, compacted soils, improper or inadequate irrigation, poor maintenance practices, improper pruning, shading by homes or buildings. Stresses created by the urban environment reduce tree life expectancy, sometimes by as much as 50%.

During the drought, I have seen an increase in tree failure, whether a limb drop or whole tree failure. In most instances, crown, limbs, branch and twig dieback were the obvious symptoms of the drought. Many times, clients mistakenly thought the dieback was caused by disease or insect, however root dieback from minimal soil moisture was the cause of crown dieback.

Now, with the heavy rainfall and wind, tree failure due to saturated soils are on the increase. Trees remain upright due to their root system. Structural and buttress roots grow outward from the trunk at the (root crown), out to the edge of the crown (known as the dripline). At the dripline, the structural roots are 1-2″ in diameter. They continue to grow outward, branching into the small, fine feeder roots that absorb moisture and nutrients. Depending on local conditions, tree roots may extend 1.5 times the tree crown diameter. Based on San Diego soil conditions, most roots grow within the upper three feet, typically 80% of the roots are within the top 18-24″ of the soil.

Roots in dry soil are held in place by friction. However, when rain saturates the ground, it acts as a lubricant, lessening the soil friction holding roots in place. When wind combines with excess weight from rain or snow, the energy is transmitted down the trunk to the roots. Soil root friction reduced by saturation causes roots to loose anchorage, resulting in a failure. When roots fail to support the tree, it is assessed as a root failure. When the entire root ball rotates up from the soil, it is a soil failure.

Homeowners with large trees in close proximity to their property should examine their trees for any change in condition as a warning sign of a potential problem. Changes to be aware of include:

Is the tree leaning?
Are there soil cracks at the base of the tree?
Is the soil lifting, tilting or rippling at the tree base?
Are there dead limbs or branches in the crown?
Is there a progression of twig, branch and limb dieback?
Did the tree drop it’s leaves abnormally early?
Did the tree not leaf out as in the past?
Any obvious open cavities, cracks or splits?
Any animals or insects nesting within a hollow, cavity or crack?
Any fluids, abnormal sap flow or other discharges from the tree?
Has irrigation been reduced or eliminated to the tree?
Has there been construction activity near the tree?
Have the roots been disturbed by any nearby utility or sidewalk work?
Is the tree sitting in water, is there proper drainage?
Has there been a change in grade near the tree?

If you can say yes to any of the above, your tree may have acquired defects that increase the risk of failure. The increased risk of failure may result in property damage or personal injury to your family, friends, or any pedestrian near the tree. A tree with a history of previous failures possesses an increased risk of failing. Trees may not present any obvious signs or symptoms of a defect. Unseen decay may exist within a limb or trunk, or as a root rot.

Whether commercial or residential property, if you are concerned about the health and safety of your trees, you should contact an arborist certified by the International Society of Arboriculture, (ISA). Once certified, the ISA allows arborists to enroll in specialized training to earn the credential of a Tree Risk Assessor Qualified. While anyone may attempt to assess the health and structural integrity of a tree, certified arborists who are qualified in tree risk assessment represent the industry standard and best management practice for tree risk assessment.

Tree risk assessment is the current best management practice to determine tree risk of failure associated with defects. The assessment utilizes a level two basic visual assessment and a two page ISA format for the assessment protocol. The assessor may determine more advanced assessment techniques are required, however usually a basic visual assessment will suffice.

If you have noticed a change in the health or condition of your tree, take proactive measures before a catastrophic accident, call a certified arborist knowledgeable in tree risk assessment.

Click here to read an article published in the LA Times Risk Assessment article.

Trees Damaging Los Angeles Infrastructure, Who Is Responsible for Liability and Repairs?

Posted on August 17, 2015 by landscapeexpert

In May and June of 2015, The Los Angeles Times published articles addressing the problem of crumbling sidewalk infrastructure within the City of Los Angeles. The articles focused on the challenges pedestrians face in this car-dominated city. After years of mounting complaints and lawsuits caused by defective, dangerous sidewalks, city officials are finally beginning to address the problems caused by trees that were planted within city parkways, medians and right of ways.

Roots have damaged the sidewalk creating a trip and fall hazard

After decades of deferred maintenance, the City Council, the Mayor, and public work officials are finally turning their attention toward addressing the problem, and trying to figure out how to juggle spending requirements resulting from legal settlements and sort out who is responsible for future sidewalk maintenance, as well as liability for future injuries caused by damaged sidewalks.

The first question, who is responsible for sidewalk repair and replacement caused by trees growing within city parkways and right of ways? California state law placed the burden of sidewalk repairs on adjacent property owners. A majority of California cities adhere to the state policy, however not the City of Los Angeles, which forty years ago opted for a policy that made the City responsible for repairing sidewalks damaged by tree roots in city parkways. Back in the 1970’s, when federal funding was available for the work, Los Angeles opted to pay for tree-damaged sidewalks. When the federal funding was depleted, voters declined to support tax increases for the repair work, leading to the current massive backlog of damaged sidewalks.

Instead of removing invasive, surface rooting tree species and replacing damaged sidewalks, the city embarked on a less expensive program of temporary asphalt patches in an attempt to smooth over displaced, uneven sidewalks. The problems continue to mount, with over 19,000 sidewalk complaints within the past five years alone. Over 40% of the complaints have been ignored, with no repairs having been made, mainly due to inspections never being made or the sidewalks so severely damaged they require complete rebuilding.

The City is now proposing a policy to address the situation. Under the proposed policy, neighborhood sidewalks damaged by city parkway trees would be replaced at the city’s expense. However, after repairs are completed, responsibility for repair, maintenance and liability would be shifted upon the adjacent property owner.

The proposal has received mixed comments from residential and commercial property owners. Businesses already pay taxes they assume local government should be using for infrastructure repairs. Additionally, requiring businesses to pay for repairs would harm retailers, especially in districts lined with problematics trees. Many commercial property owners would be forced to pass on the expense to the small business owners that rent the property.

Ficus roots creating a sidewalk hazard

Under the “fix and release” program, repairs would be made by the city, and then future responsibility for the sidewalks transferred to the homeowner. Some homeowners feel this would be an equitable solution to the current problem, other disagree, stating they would be saddled with big bills down the road, particularly if the city does not fix the “root” cause of the problem, that being tree roots or leaking utilities.

The city must grapple with both sides of a delicate issue, trying to preserve the benefits of large, picturesque trees providing neighborhood character while having to remove the same trees whose invasive roots have damaged infrastructure and would continue to do so if left in place. To begin the process, the city acknowledged they do not really know how extensive the problem is. The city has no existing tree inventory of the tree and sidewalk condition. Without this information, it would be difficult for the city to measure progress as they attempt to implement any new sidewalk management policy.

Certified and registered consulting arborists consult with Southern California municipalities and private property owners involved in trip and fall litigation caused by tree root lifted and damaged sidewalks. Typically lifted and damaged sidewalks caused by tree roots are due to inappropriate tree selection. Species such as Sycamore, Ficus, Eucalyptus and Ash trees planted decades ago in restricted parkway planters were most often associated with damaged infrastructure.

Sidewalk repair or replacement without addressing the existing tree species ignores the problem. Passing on responsibility for future repairs and liability to adjacent property owners would be an unjust situation for taxpayers. Large, surface rooting, invasive species should be closely examined for mitigation in conjunction with infrastructure replacement. Perhaps root pruning and root barriers might be an appropriate remediation that would protect future infrastructure while retaining large pre-existing species.

However, many species planted decades ago were and will always be inappropriate for confined parkways. Root pruning a large Ficus or Sycamore could easily de-stabilize the tree, resulting in a catastrophic failure. Who would be liable for a tree failure and resultant property damage, or worse, personal injury or death? Citizens might have to accept they cannot have the best of both worlds, where large, invasive trees are retained for neighborhood character, sidewalks are repaired and the city remains responsible.

Over the decades, many newer street tree species have been developed that provide desirable growth characteristics while minimizing damaging invasive root systems and towering canopies that conflict with traffic and overhead utilities. Reasonable compromises can and should be made toward replacing older, inappropriate tree species with newer species that will provide community benefits while minimizing maintenance costs and damaged infrastructure.

Hopefully, the City of Los Angeles and other municipalities facing this problem elect to use certified and registered consulting arborist and horticulturists as they consider how to address their urban forest and infrastructure issues.

To read the full Los Angeles Times Article, click the link:

L.A. Considers Shifting Responsibility to Property Owners