Presentation on theme: "Healthy Trees- Sustainable Landscape ASLA National Conference 2008 Chris A. Cowles Senior Urban Forester ISA Certified Arborist ®, MD LP Forester, MD Licensed."— Presentation transcript:
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 About TCOT About me About Healthy Trees About you Infrastructure Renovations for 23 rd 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, MD- November 1992
15 Honey Locust: root radius = 34 feet Another root myth debunked Myth Busters 4 th Annual National Capitol Root Appreciation Day Manassas Park High School Manassas, VA
Why did we need new methods? How do we find them? And what did the CEO not ask for…? Baltimore Life Home Office, Owings Mills, MD 1992 and 2008
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. Northern Red Oak Kwanza Flowering Cherry
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 END AT EST 50 Concept Design for Proposed Corporate Financial Center National Rural Utilities, Dulles Town Center, VA
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. Renovations to Pennsylvania State Capitol South Park Landscape
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 outShall 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 & 15 th 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
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 Sustaining Trees in grade fills in site design
But does it work? 10 years later… Are we Sustainable yet?
Root Aeration Systems from 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 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 $ / 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 Mycorrhizal adds 400 x absorption Macropods transport water
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: 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. Decompose plant residues rapidly. Produce hormones that help plants grow. Produce good soil structure, improving water infiltration, oxygen diffusion, and water- holding 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