Transcript New Technology in Tree Preservation Presented to The

Healthy Trees- Sustainable Landscape
ASLA National Conference 2008
Chris A. Cowles
Senior Urban Forester
ISA Certified Arborist®, MD LP Forester, MD Licensed Tree Expert
Introduction
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About TCOT
About me
About Healthy Trees
About you
Infrastructure Renovations for
23rd Street Median
Crystal City, VA
Session Overview
• Where do Health Trees
begin? Getting to the
Root of the Problem
• Design for Sustainability
• New Techniques for
Success in Healthy
Trees
• Q&A
“If someday we are to know
everything there is to know
about the above ground
portion of the tree, we will
still only know…”
Dr. Alex Shigo
US Forest Service
“…half the story!”
Healthy Trees start
with Healthy Roots“Myth Busters”
• Do tree roots
really extend only
to the drip-lines?
• What about taproots,
mirror images, &
formulas…?
“First Annual National Capitol Root
Appreciation Day”
Rock Spring Park, Bethesda, MDNovember 1992
Myth Busters
• 15” Honey Locust:
• root radius = 34 feet
• Another root myth
debunked
4th Annual National Capitol
Root Appreciation Day
Manassas Park High School
Manassas, VA
Why did we need new methods?
How do we find them?
Baltimore Life
Home Office,
Owings Mills, MD
1992 and 2008
And what did the CEO not ask for…?
Healthy Trees in construction come from
teamwork and begin at the Design Table
Who do you invite to your Table?
Sustainable Design vs Design
Afterthoughts
Supersonic Air-Tools
Geo-composites for Healthy
Root
Healthy Soil Biology
US Senate Park Perimeter Security
Conceptual Design / Build Team
How do we use trees as Design Elements? Or are they mere
“Afterthoughts”?
If the trees are a design element, not an after-thought, then
you have Sustainable in your Design.
5 years later… “Are we Sustainable yet?”
“Where are the roots?”
• Mach 2 Supersonic Air-tool
(SSAT) for Root Investigation
• Question for the professors: “How
fast is MACH 2?”
Root Investigation for Senate
Park Perimeter Security Design
Document findings and prepare
recommendations for design modification.
“Kwanza” Flowering Cherry
Northern Red Oak
Proposed US Capitol Security Bollards
Assess impact and determine alternate design
& construction procedures
Root Investigative Study Report
Objectives: Determine growth
characteristics of representative tree
species in Loudoun County, VA by means of
investigative digging in representative
species, soils and hydrological regime. The
results of this Study are used to determine
strategies in design and construction as
well as prescribe appropriate protection
measures & stress reduction therapies.
Beginning Supersonic Airtool (SSAT)
Investigation within proposed roadway
selecting representative tree species:
White Oak, Red Oak, Hickory, Ash.
Note roots are very
near surface. This is
not characteristic of
white oaks in
Montgomery County
MD Piedmont in
loamy clay mica rich
soils. Deeper
restrictive layers are
assumed to be the
reason. Refer to soils
boring reports for
verification.
Technical Findings
23” WHITE OAK
(white paint for
photo)
• TOTAL ROOT
LENGTH (est.) = 50’
• DIAM. AT DIST.
FROM TRUNK
• 3” @ 10’
• 1” @ 20’
• .5- .75” @ 30’
• .25-.5” @ 40’
•END AT EST 50’
Concept Design for Proposed Corporate Financial Center
National Rural Utilities, Dulles Town Center, VA
Renovations to Pennsylvania State Capitol South Park Landscape
Several locations at
the Pennsylvania
State Capitol South
Park were identified
with trees which are
having potential
design elements
installed or
renovated within
their Critical Root
Zones (CRZs) with
potential for major
impacts. These
design elements are
storm drain pipe and
infiltration beds,
concrete steps,
electric site light
conduits, retaining
walls, water lines,
and walk demolition
and reconstruction.
Construction
Superintendent
documenting
significant
root depth and
location for
design of grade
beam.
Renovations of
private residence in
Philadelphia, PA
Utilize SSAT for lowering grade within CRZs for new sidewalk
Root Investigation during demolition to determine need for special
design modifications for retaining 38” Quercus phellos.
Independence Avenue Streetscape Renovation at the
US Capitol House Office Building aka “Longworth Oak”
5 years later….
• Working inside the
critical root zone with
SSAT
• Inserting $3,000 light pole
base between 2 mature
Quercus phellos at the historic
Homewood House
Johns Hopkins University Homewood Campus
Baltimore, MD
Landscape Renovations Design / Build
• Sprinkler and low voltage
electrical cable installation
– “But we are only digging less
than a foot deep!”
• Architects: Cross out
“Shall be hand excavated”
in your Master Spec!
Root Pruning with SSAT / Hand Tools for roots > 1.5”
diameter or within inner ½ of CRZ radius.
Method of Root Pruning to be determined….
Perimeter Security for Lafayette Park, Pennsylvania Ave & 15th Street, Wash. DC
“Smithsonian Level” Root Pruning
at the Haupt Garden, Washington DC
Utilizing the SuperSonic Shop Vac (SSSV)
Problem: Sustaining Healthy Trees on a Campus or Commercial
Site with poor soils or pedestrian compaction over time.
• Native healthy topsoils = 80%
compaction;
• Urban sites easily 90% - 98%.
• How can you “decompact”
soils without root damage?
• SSAT to the rescue!
Radial Mulching with SSAT to “De-compact” Soils
• Backfill with 50% Organic Compost
• Excellent time for Compost
Teas / Humates
• Stand Back!
Shady Grove Adventist Hospital
Renovations, Gaithersburg, MD
• Subsurface basal
decay can be verified
as well as “Girdling root”
investigation can be
done at same time
Sustaining trees in grade fills in site
design
• 48” DBH
Hickory
Where to put
Phase I to
Phase II
connecting
drive?
T. Rowe Price Financial Center
Owings Mills, MD 1995
Sustaining Trees in grade fills in site
design
• Grade fills proposed within the
CRZ require special design
modification and special
construction procedures
• “Root friendly” pavement
section employing the latest in
ground engaging technologies
But does it work? 10 years later… “Are we
Sustainable yet?”
Root Aeration Systems from 1983 -1993
Baltimore Life Insurance Home Office, Owings Mills Corporate Park, MD 1993
15 years later…
And what question did the CEO not ask…?
Latest Root Aeration Mat (RAM) from 1996 -2008
• Specialty Triple Ply
Geocomposite
• Flexible, ease of installation,
less expensive
• CAUTION: Experienced
Geotechnical Specialist
prescribed for each soils &
loading potential.
• Specification, layout,
installation, only under
direction of Certified Arborist /
Forester experienced in root
engaging technologies.
Root Aeration System Design Guideline for Preserving Trees in Construction Grade Fills
This handout was designed to assist site design professionals or agency reviewing staff with basic understanding of objectives, limitations, and parameters to consider in tree
preservation dealing with issues of proposed grade fills.
The purpose of the Root Aeration Mat (RAM) is two-fold: first, to provide necessary air/gas exchange between the atmosphere and the critical root zone that will be covered by a proposed
grade fill situation; and second, to spread this loading and provide a stable base in conjunction with other engineered materials to support the proposed structural or nonstructural fills.
Roots of trees for the most part require porous soils of 80% compaction as found in forest soils. Even fills of a few inches over the existing grade of roots can bring about suffocation and
toxic build up in a short time. Root Aeration Systems have been employed successfully for many years in a wide variety of construction scenarios, including retaining walls, parking lots, state
highways, and toe of slope conditions.
Each site and application varies thus materials and design will vary. The Care of Trees, Inc. Foresters familiar with tree root structure and functioning in relation to species, soils, and
moisture regime impacted by construction situations will review the design scenario and site, prescribe specifications, layout and supervise installation. Our latest methods and materials are
beyond those found in state or local manuals.
Caution: Only licensed professionals with much experience in root system investigations and impact from design and construction impacts should attempt to specify and prescribe root
engaging technologies. To meet structural concerns an experienced geotechnical professional should be engaged in product and materials selections under proposed paving or curbs.
The following are step by step guidelines that apply to a wide variety of situations:
1. The Project Forester or ISA Certified Arborist will determine the health and condition of trees in consideration. Will the tree withstand added construction stress? Are they worthy of
consideration for special preservation measures? What is past maintenance history or prior impacts from site development?
2. Based upon accurate tree survey location including grades at base of tree, determine the appropriate Critical Root Zone for the tree(s. Investigative digging may be needed since
roots vary in width and depth with species, soil type, moisture level, and urban infrastructure involved. (Refer to CRZ Handout sheets)
3. Project Forester will review grading and utility plans with the appropriate design team. How and where will cut and fill impact the CRZ? How will proposed utilities impact CRZ? Are
there options for utility placement?
4. Determine how many square feet of Root Aeration Mat are needed?
5. No soil should ever contact that part of the tree normally above ground. How is soil to be kept from the trunk or root flare? If a retaining wall is needed what design and material will fit
the tree root system based upon the investigative dig?
6. The project forester will design the appropriate venting system to fit the site and objectives. How will the RAM be vented to atmospheric conditions for the air/ gas exchange to the
soil surface? Will a retaining wall, curb, or toe of slope be used?
7. For installation under structural fills the review of a geotechnical professional is required. We will not install structural systems unless a geotechnical has reviewed and approved. If
none are available that are familiar with this system we can provide geotechnical analysis and answer design loading questions.
8. For structural fills typically 24” is minimum needed between existing grade and proposed finish grade of pavement. Geogrids and other stabilization methods can be prescribed
when less than 24” is available.
9. Resolve additional pertinent design / construction issues:
10. What will be the appropriate sequence of events to facilitate construction but not compromise protection of the tree root system?
b. Will the est. impact to the trees require related tree protection items such as root pruning and silt/tree protection fence? How will those be sequenced?
c. Will additional arboriculture specifications be prescribed for the impacted trees? These may include mulching; fertilization/ soil conditioners;; crown pruning;
cabling/lightning protection; and IPM needs.
d. How will selective removal of saplings, brush, and vines within the protected CRZ be prescribed?
11. All work within the CRZ shall be laid out by the project forester or arborist and reviewed by the landscape architect/ civil and site superintendent. Installation should always be
by ISA Certified Arborist with experience in this type of work.
Budget number for the root aeration mat systems is usually between $ 2.00- 3.00/ square foot installed depending upon degree of difficulty and economies of scale.
For a site / tree assessment and plan review contact one of our local offices.
For an in- office educational power point presentation regarding these and other state of the are tree preservation planning, design, or construction measures, call the below office.
The Care of Trees, Inc., the leader in “root engaging technologies”.
Sustaining Roots- Design Guideline for
Preserving Trees in Construction Grade Fills
The purpose of the Root Aeration Mat (RAM) is two-fold: 1) Provide
atmospheric gas exchange, 2) Stabilize and spread the load.
• Roots of trees for the most part require porous soils
• No soil should ever contact that part
of the tree normally above ground
• The project forester will design the appropriate
venting system to fit the site and objectives
• For installation under structural fills the review
of a geotechnical professional is required
• For structural fills typically 24” is minimum needed between
existing grade and proposed finish grade of pavement
• Resolve additional pertinent design/construction issues
• All work within the CRZ shall be laid out by the project forester
or arborist and reviewed by the landscape architect/ civil and
site superintendent
How do we sustain roots adjacent to building
excavations but still allow room to build?
Healthy Roots at the edge- A solution to the
interface of SuperSilt Fence LOD / TPF that
avoids cutting roots for SSF
How do we build a masonry structure
between 2 prized mature trees?
• Incorporate Root Protection
Matting (RPM) into the design
and construction
Private residence on Hillmead Rd,
Bethesda, MD.
Root Protection Mat Specifications
Root Protection Mat within CRZs (as designated on TPAK):
Objective of RPM is to allow designated construction activities within the trees protected critical root zone
with minimal compaction or rutting to surface soils and root system. Methods and procedures for
demolition of RPM is just as critical as the proper installation.
RPM specifications are always a function of parent soil make- up and projected loading (static VS dynamic
compaction) and frequency / number of trips. Soil make-up can vary with seasons (wet vs dry).
Experienced geotechnical representative should be consulted once exact loading potential is known.
Exact location / layout of RPM to be approved by project forester.
Storm & Sanitary Sewer Excavation with steel tracked excavator:
- 2 layers RPM over wood chips with Alturnamat
Water line or conduit excavation using rubber tracked mini- excavator with psi 4.2 or less with operator
and load):
- 2" mulch + Triplaner Geonet (double sided) for equipment operation and soils stockpile within CRZ of
protected trees.
Temporary Mobile Home/ Construction Trailer with no vehicle parking-same as above. Use Rubber tracked skid steer for installation. All access within CRZs on RPM.
Staging/ Stockpile Area for heavy equipment/ trucks within CRZs- Amerdrain Soil Drainage Mat+Triplanar Geonet+ Bi-axil Geogrid + 12" Crushed stone with silt fence
(installed on-grade) perimeter.
Above Staging/ Stockpile outside CRZs use only Geonet with crushed stone.Add Geogrid if concrete
trucks or construction fork lifts are used repeatedly.
Recommend installation only by contract arborist experienced in Root Protection Matting for
various applications.
Temporary Root Protection Mat
Guidelines
• Root protection mat within CRZs (as
enumerated on TPPK)
• Storm & sanitary sewer excavation
• 2" mulch + Triplaner Geonet (double sided)
• Temporary mobile home/ construction trailer
• Staging / stockpile area
• Recommend installation only by contract arborist
experienced in root protection matting for
various applications
Stress Reduction- Healthy Soil Biology
is Key for Urban Trees
How sustainable is your Rhizosphere?
Fungal strands with sand grains for drainage
Macropods transport water
Mycorrhizal adds 400 x absorption
The Soil Food Web + Roots = Rhyzosphere
All Soil Food Webs Are Not The Same
• Grasses, Shrubs,
Deciduous Trees and
Coniferous Trees prefer
different SFWs.
• As ecosystems move
from grassland / turf to
forestland they move
from high bacterial to high
fungal.
Sustainable Soil Quality
A balanced Soil Food Web will:
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Suppress disease-causing
and pest organisms.
Retain nitrogen and
other nutrients
Make nutrients available for plant
growth at the times plants require
at the rates plants require.
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Decompose plant residues rapidly.
Produce hormones that help
plants grow.
Produce good soil structure,
improving water infiltration,
oxygen diffusion, and waterholding capacity.
Consume pollutants in the soil.
Be aware that these functions are entirely biological and only occur through a
soil foodweb that is built-up, intact, and working.
How does this work?
Sounds good in theory, but does it work?
For More Information
• USDA National
Resources Conservation
Service
– Soil Quality Institute
– http://soils.usda.gov/sqi/
index.html
– Photos courtesy of this
source
Is it The End
or The Beginning?