"Low
Impact Development Landscape Codes,
The
Louisiana
Model Landscape Code”
Prof.
Buck Abbey, ASLA, CELA
Louisiana
State
University
,
Baton Rouge
,
Louisiana
© all rights reserved.
Abstract
Landscape codes enacted in cities and towns can be amended to
incorporate low impact development principles following some of the ideas used
in the State of
Louisiana Model
Landscape Code recently published by the State of
Louisiana Department of Environmental Quality. Contained within this model code
are recommended on-site storm water best management practices and twelve
principles of on-site storm water management that can be incorporated into the
language of a community zoning ordinance. These
principles will provide that a certain percentage of all development sites must
remain permeable and will allow that a proscribed percentage of site rainfall
is to be captured and disposed of on-site, rather than be allowed to run off
and be disposed of in centralized collection facilities at high tax payer
expense. Storm water collected on-site from roof tops, paved areas and open
lawns shall be infiltrated or treated within storm water BMP’s and recycled
into planted landscape areas or harvested for yard sprinkler systems.
PURPOSE
OF LANDSCAPE CODES
Landscape regulations, often called ‘green
laws’ are enacted by communities to encourage better site design and more
responsible development to the end that society’s needs are satisfied while
nature is protected, preserved or rebuilt within urbanizing areas. Each
community benefits by keeping natural systems a functioning part of the
infrastructure of a city. Natural systems within any community provide services
for society and these services can be calculated as cost savings to
taxpayers. Nature in the city works to
cool the climate, clean surface water, filter the air, maintain soil structure,
remove pollutants and enhance visual quality. Vegetation is one of nature’s
prime systems that can be useful in cleaning the environment. Studies have
shown that nature maintained within the city can save taxpayers millions of
dollars by reducing storm water management costs, cleaning the air, lowing
ambient temperatures and thereby utility costs and reducing sedimentation
pollutant transport. Each building site in a community should do its part in
preserving or rebuilding natural systems. This code will assist in this mission
to keep nature as a functioning part of the community.
The landscape code presented here, in its
simplest description, is a set of community development policies in the form of
zoning ordinance standards that require sensible site planning which in turn
will reduce environmental and visual impacts to neighborhoods in urban
communities. Landscape codes adopted by American cities may contain a variety
of design standards that affect landscaping, on-site storm water management,
habitat preservation, tree protection, water conservation and irrigation use
requirements. Typical design components are listed in Fig.
1.0 and can be seen in context on the drawing shown in Fig. 2.0. These are typical municipal green policies
that will pay dividends to communities, citizens and developers alike. This model code incorporates low impact development (LID)
strategies as the principal conceptual thread that runs though all segments of
the code.
THE MODEL LANDSCAPE CODE
The Model Landscape Code recently written
for the State of Louisiana Department of Environmental Quality sets forth
design and performance standards for site landscaping and on-site storm water
management on zoned development sites. The model code can be incorporated into
community zoning ordinances as design standards to assist with the management
of storm water on small development sites. The code also addresses related
landscaping, irrigation, water conservation and tree and habitat preservation
standards that together form the basis of good site planning practices
encouraged by zoning.
This model ordinance is also particularly
well suited to become part of a community’s 404 Phase II Storm Water Management
Plan. On-site storm water management with landscaping, vegetation and urban
forestry practices is recognized as an essential element of minimum control
measures for post construction run-off control as promulgated in 404 Phase II
rules. These rules have been proposed by
EPA to clean the navigable waters of the United States. The principles and
methods set forth in the model code will work to ameliorate non-point source
water pollution stemming from built up urban areas in most coastal states.
The language of this model code has been prepared
for information purposes only but communities will find it helpful in drafting
low impact development clauses within their community landscape code. Communities that wish to modify and adopt
this code may do so but should do so after careful review of local codes, laws,
public procedures and building criteria. Communities are also encouraged to
seek advice from counsel as well as design professionals who practice in the
community and who are familiar with rainfall patterns, soil types and local drainage
methods.
Reference is made throughout the model to
‘municipality’ in this model code and that term may be replaced with the name
of any ‘jurisdiction’ that may adopt the minimal storm water and landscaping
guidelines contained within the model. Likewise, names of designated officials,
departments, reference codes, local laws, ordinances and policies, reference
books, and design guidelines may be knowingly substituted where found. Local
option changes or ‘flexible administrative standards’ are designated in blue text within brackets and these all must be
changed to meet local conditions.
Notes shown at the bottom of certain
pages and commentary placed within the text throughout the model are
instructional and not intended to be adopted as part of the code. Supplemental
information has been embedded with the use of hyperlinks on a copy of the model
code located on website version of the code.
Readers will find embedded “code definitions”, “technical standards” and
“illustrative drawings” are included to increase the reader’s understanding and
control over the document.
Several design manuals from various
coastal states with conditions similar to Louisiana are referenced in this code. They
are supplemental to this model and provide additional technical content for the
design of storm water facilities. Users are cautioned that some of the
standards, specifications and other technical details may not apply to
locations other than from where the original design manual was crafted. The
Landscape Design, Irrigation and Tree Manual (LDIT Manual) mentioned throughout
the document must be written by the User or the User’s consultant to tailor the
document to local conditions. Design
Manuals are companion documents to a landscape code which are prepared to summarize
the technical language of a landscape code, set specific design parameters and
explain administrative procedures
involved preparing landscape design plans and seeking permits for conditional use of the property, building,
drainage and occupancy.
An interactive of version of the model
landscape code referenced in this paper is available on line at www.abbey-associates,com/splash-splash.
LOW
IMPACT DEVELOPMENT
Low Impact Development is defined as “an
approach to land development that uses various land planning, design practices
and technologies to simultaneously conserve and protect natural resource
systems and reduce infrastructure costs. (1)
The LID strategies incorporated into this
model code are based upon the landscape architecture idea that natural site
processes and environmental forces should be applied to the design of each
building site in a proactive way so that nature is called upon to provide
environmental services. Understanding non-point pollution reduction in light of
storm water management provides one good example of how nature can be put to
work cleaning storm water. The strategies suggested here will allow nature to
remove pollutants such as suspended solids, trace metals, total nitrogen, total
phosphorus, bacteria, organic material, nutrients, litter, yard and animal
waste from the run off of developed properties.
The EPA has identified ninety-four (94)
contaminates that are moved from place to place by storm water flows. Storm
water moves pollutants from unidentified sources such as developed land into
public conveyance systems and then into fresh water bodies where large
concentrations can build up in the enviormment. This is what non-point
pollution is and why it can affect our surface waters, wells and underground
water supplies if left unmanaged.
LID strategies suggested in this model
code promote sensible site planning that use native and ornamental plants,
minimize site disturbance and preserve trees and other significant habitat all
of which can clean storm water. In addition, plant materials filter out
contaminates and can hold them in place. In the case of nitrogen, phosphorus
and carbon dioxide, vegetation absorbs these elements and converts them to plant
growth. Oxygen as we all know is an element essential for life on earth and is
broken down within vegetation from carbon dioxide which in large concentrations
can be harmful to mankind. The low
impact development strategies within the model code will reduce the impact of
development through the reduction of lawn grass, maintenance of natural
drainage, the conservation of potable water and the recycling of storm water
for irrigation use. These are all LID
practices that can be promoted with the use of a community landscape code.
Several low impact development objectives
are contained within the theoretical construct of the model code. They include.
1. The total amount of impervious surface
is reduced and the amount of plantable green space is maximized.
2. Storm water is managed where it falls,
(on-site storm water management) rather than allow it to flow downstream to
centralized collection facilities that must be maintained at great public
expense.
3. Connected chains of natural sel
maintaining treatment systems (storm water bmp’s) are used to collect storm
water quantities and pollutant loads. (1)
In addition, native and or ornamental
plant materials will be used to assist in the establishment of these
objectives. Plant materials are very useful in cleaning run off through
filtering, absorption and evapo-transpiration. The low impact development
strategies within the model code rely upon plant materials and natural systems much more than structural materials.
Finally, the model will allow communities
to broaden their storm water management regulations by supplementing
traditional methods of centralized storm water management.
The Louisiana
model can add decentralized storm water management
techniques to local zoning and building regulations. This decentralized
approach works to detain, filter, evaporate, absorb and infiltrate a percentage
of storm water where it falls, rather than convey it to centralized disposal
areas at public expense.
Decentralized rainfall management uses a
series of storm water best management practices
(BMP’s) that reduce the use of traditional catch basins, manholes, underground
pipe, force mains, head walls and off-site disposal into drainage ditches and
then into fresh water bodies. Instead, storm water BMP’s use natural systems
such as wetlands, parking detentions, planted buffers, retentions soil, sunlight and vegetation
as the primary means of disposing of rain water in environmentally friendly
ways. These
storm water management methods are listed in Fig. 3.0 and
can be seen in context on the drawing shown in Fig.
4.0.
Natural methods using storm water BMP’s
do this by modification to land surfaces that change run-off characteristics,
increase time of concentration and amount of infiltration. (2) The primary purpose of this model landscape code
is to solve a vexing problem of community site development that presently
allows property developers to increase the amount of storm water run-off and
its attendant non-point pollution carrying capacity. Elevated run-off volumes
from over-developed land are
environmental problems that can be solved with the use of this model code.
STORM
WATER BEST MANAGEMENT PRACTICES
The Environmental Protection Agency
recommends many storm water best management practices that can be included
within local landscape codes. (3) The Low Impact
Development Manual prepared by the United States Department of Housing and
Urban Development sets forth standards for storm water conveyance and collection systems as well as
alternatives to conventional systems such as sustainable drainage methods based
upon infiltration, bio-retention, dry wells, filtering systems and constructed
wetlands all of which can be used to reduce run off and pollutant loads. (4) The
Louisiana Model Codes includes those storm water best management practices set
forth in Fig. 3.0
LID
PRINCIPLES
This model landscape code is a site
development-friendly method that encourages developers to landscape their
development sites in combination with non-structural storm water best
management practices in such a way as to maintain existing run-off rates at predevelopment
levels while at the same time adding to the visual appeal of the property
though the use of landscape plants and design. This method of site construction
favors nature and works to utilize natural methods for controlling site
development impacts while at the same time reducing development costs. LID
principles driving the development of this code include a) better site design,
b) minimization of impervious surfaces, c) protection of
natural drainage features and existing tree vegetation, d) reduction in land
disturbance activities, e) promotion of low maintenance landscaping that
reduces the use of herbicides, fertilizers, pesticides and lawn grass, f)
protection of stream banks and lake edges, and g) increases storm water ‘time
of concentration’ at site outfalls. The
emphasis of the LID storm water best management practices in this code is on
the use of non-structural storm water best management practices
as defined by the Environmental Protection Agency. Non-structural methods,
which also can be called ‘micro-methods’ of storm water management, are best
used on small parcels of land where available space is limited and
decentralized drainage is practical and efficient. This is often the case in
the city and suburban fringe where landscape codes are utilized for better land
use practices and site design performance on small sites generally less than
five (5) acres in extent. Non-structural
methods do not use complicated engineering formulas to calculate water flow and
capture and release. Non-structural methods are designed according to the
principle that trapping rainwater where it falls, or close to where it falls,
reduces the volume headed downstream. In addition, when rain water is conveyed
off-site to down stream disposal areas greater amounts of land and expense are needed for its management. This code shows how
small planted areas set aside on every development site can collect rainfall
volumes that exceed an average design storm. See the proto-type design
drawing to see how the on-site storm water BMP can be arranged on a
site plan.
These micro-methods of storm water
management rely upon ground shaping, surface material selection, recharge
capability improvement and vegetation plantings to modify the infiltration
capabilities of grassed landforms, beds and planted buffers. These earth
friendly methods that replicate nature’s methods of storm water management make
it easy for landscape architects, engineers or contractors to design site
facilities to better detain, retain and infiltrate storm water. Landscape
design practices also make it easy for landscape contractors who build and
plant project sites to manipulate ground surfaces to capture rainfall.
Non-structural methods allow for better site design, open space design, urban
forestry, buffer zones, zoning and ordinance compliance all of which are common
procedures for managing minor storm water flows.
However structural
storm water best management practices are referred to in this code.
Structural methods are used to intercept and store larger amounts of storm
water on properties larger than five (5) acres. Engineering formulas are often
used to develop storm water management plans for very large parcels of land.
These plans often make use of structural methods to capture, detain, retain and
release storm water at predetermined rates. Structural methods such as
retention ponds, constructed wetlands, open channel systems, porous paving, and
disconnected roof tops and underground storm water chambers are common
structural methods of storm water management that often require engineered
solutions in order to function properly.
Structural methods also allow for detention, infiltration, exfiltration,
evapo-transpiration and filtering all of which are common
procedures for dissipating storm water.
Many communities have storm water design
codes that contain procedures and formulas for the design of structural storm
water best management practices so it would be repetitive to include these
methods that often involve heavy construction practices in this model code. Also, the structural methods do not utilize
vegetation in any meaningful way so that too is a factor why this code does not
place emphasis on structural methods but rather places it on non-structural
methods that use vegetation, amended soils and other natural materials.
BETTER
SITE DESIGN
The secondary purpose of this model
landscape code is to assist communities in enacting design standards for better
site development in regard to landscape design, landscape construction
practices and earth friendly site maintenance methods. Through better landscape
design, natural habitats can be preserved, building sites can be adequately
buffered from public streets and adjacent conflicting land uses and parking
lots can be built that cool the climate, filter the air and absorb storm
water. These are nature’s methods of
cleaning and filtering water.
Landscape codes better define the design
of yard areas,
open space, buffers, and parking lots of building sites as
used in zoning practice. Fig. 2.0 A properly crafted landscape code will require
more effective planting, screening, irrigation, water conservation, landscape
construction and maintenance practices. Landscape codes are written with an
understanding of the building site where
each part or use area of a site from the “street yard” to “the parking lot screen” to “site service areas” to “street wall buffers” require vegetation plantings. Communities
that adopt landscape ordinances set design standards for these various site
spaces collectively known as the “geography of the building site” are better
places to live as a result of design. Design standards are based upon some form
of measure. They are always quantifiable
and are usually linear measure, square footage, square yards, cubic yard,
volume or some other common measure that can be calculated by plan inspectors
and landscape administrators.
Storm water management and landscaping
are very complementary on any development site. This model code brings together
two aspects of site development that are usually covered by separate
development codes within a community’s set of zoning and development
ordinances.
DESIGN
PRINCIPLES IN THE MODEL CODE.
The model landscape code has been tested
on the drawing board to determine the relationship between impervious and
pervious spaces on a typical development site. A case study site consisting of 62,500.00 square feet of development and 32,650.00 square feet of permeable area was used
to examine proposed landscape design components, technical standards and the
placement and size of storm water best management practices. The following on-site
storm water design principles are recommended for setting design standards for the
various design components incorporated into community landscape codes. They include:
1.
Total Site Area (TSA) of any zoned lot
will consist of development, vegetative areas and on-site storm water
management facilities.
2.
Vegetative Areas (VA) or design
components of the landscape code become on-site storm water management
facilities.
3.
Design Storms of one (1) inch rainfall
will require a detention of a minimum 1.3 percent of the project site
or 576 square
feet (12’ x 48’) in size per acre of TSA
to capture and infiltrate the water volume. (TSA x .013 or).
Sixty percent
(60%) of storm water must be retained on site.
4.
Street Yard Buffers (SYB) and Side Buffers
(SB) for storm water management, planting and screening comprising 30 percent of TSA. (TSA x .30)
5.
Street Yard Buffers of a minimum of 78 percent of required front set back width. (FSB x .78=25’)
6.
Side Buffer Width to meet zoning
standards of a minimum of 6 percent of property
width. (PW x .06)
7.
A Permeability Ratio (PA) between TSA and
permeable open space of at least 52.2 percent. (TSA x .543)
8.
VUA Parking Areas (VUAP) used for car
storage, planting and storm water management shall containing a minimum of 12.3 percent permeable
planted area. (PA x .123)
9.
Street Wall planting areas sized for
building façade enhancement and roof top run off collection of a minimum width
of 2/10 the height of the building. (BH x .20)
10. Stream
Bank Buffers or Water Front Yards of a minimum depth of 50 percent of stream width. ( SW x .50)
11.
Storm Water BMP’s recommended by the
EPA/LDEQ consists of bio-swales, planted buffers, grassed swales, sand filters,
micro-detentions, infiltration trenches, irrigation cisterns, storm water
chambers, porous paving, preserved forest floor, protected wetlands and
constructed wetlands. See Fig. 3.0.
12. Site Design based upon these principles is imperative to achieve the
proper relationship between development, vegetative areas and on-site storm
water management facilities. (5)
Some
variation to these principles can exist of course and communities are free to
adjust the principles to meet local conditions as recommended by local design
professionals engaged in the management of storm water. These principles have been tested by the
researchers and will bring a good relationship between pervious areas of a site
and the impervious areas of a site such as rooftop/building footprint, parking
lots and paved areas that add to run off volumes.
STRUCTURE
OF THE MODEL CODE
The landscape code presented here is often
referred to as a ‘Part’ or ‘Chapter’ of some important public policy such as
the municipal code, community zoning
ordinance, land development regulations, or the building code. These are the
significant land development policies which control community development, land
conversion or civil infrastructure.
Subsections of the Part consist of titles, sections, subsections, minor
sections, headings, and sub-headings of the policy. Parts are often written by ‘title’ that
describe specific regulations. These regulations are clarified by sections,
subsections and as many headings and subheadings as necessary. These regulations are best grouped together
to make the laws more complete and understandable. The model used here follows the model code
outline presented in the book U.S.
Landscape Ordinances, John Wiley & Sons, 1998 which assembles the
information by context, technical standards, and administrative procedures.
Together, they describe the regulations and what is expected, who is involved
and the criteria by which activities and actions are judged. They are presented
in the code in sequence to allow for ease of reading and interpretation.
The context, standards and procedures are
presented sequentially in the following model code for ease of
readability. Context sets the parameters
of the code and relates the code to enabling legislation, other community codes
and important needs that the code is designed to address. Technical standards consist of design
component and technical requirements that cover landscape design, storm water management
technology, irrigation design, tree preservation, planning and preparation of
landscape plans. There are largely technical matters and design guidelines that
concern professionals such as landscape architects, engineers, architects,
contractors and builders all of whom are called upon by property developers to
assist in the conversion of land to new development or redevelopment. The
administrative procedures are the enforcement and public service mechanisms of
the model and this part of the code specifies management routines for
administration of the code including Design Manual(s), personnel, plan reviews, site inspections and
issuance of permits for tree removal, building and occupancy.
Technical standards, which are the
central purpose of this model code, cover two broad areas: the area to be
landscaped and the planting requirements within that area. On-site storm water management strategies are
discussed within each component in order to increase the amount of storm water
that is captured, stored and infiltrated upon the development site.
The former is involved with typical
landscaping design components such as ‘street yards,’ ‘buffers,’ ‘vehicular use
area’ and ‘tree preservation’ all of which are carefully defined within Sec.
17.4.A. Sub. Sec.1-9 that follows. The
latter, the storm water strategies, references on-site storm water capture and
disposal through the innovative use of storm water BMP’s such as sand filters,
rain gardens, micro-detentions, vegetative swales, roof top disconnections and
underground storm water chambers. Storm
water management technical standards can be seen in Sec. 17.8. These standards
are complemented by standards for irrigation, water conservation, land clearing,
tree preservation and habitat protection. Landscape, irrigation, tree
preservation plan preparation requirements are treated incidentally to these
main topics.
The third element of this model ordinance
includes the ‘administration procedures’. This perhaps is the most important
part of a successful public ordinance. A well thought out administrative
procedure managed by a well trained inspection staff allows developers,
builders, designers and the general public to know what the code expects and
what steps must be taken by the applicant for plan review, approval, fee
payment and permit release. Sections have been added within the administrative
procedures part of this model to organize a public advisory commission known as
a Tree And Landscape Commission who will work
with municipal staff on all issues associated with this ordinance.
Administrative procedures establish criteria for selection of Commission
members and appointment of a Landscape Administrator to oversee the natural and
scenic resources of a community. A
person who does this is essentially the Chief Environmental Officer for the
community and their major responsibility is to look after nature in the city
and be its prime advocate. This person should be someone highly trained in the
understanding of nature and design within urban areas such as a landscape
architect, arborist, urban forester, natural resource scientist or other
qualified individual. Sections within this part of the code provide support to
the development community through education programs, plan review, permit
procedures and working with the development community to find better ways of
site design and storm water management while meeting the requirements of these
policies.
Additional information is available from LSU at www.greenlaws.lsu.edu. (6)
3874 Words
END OF TEXT,
BEGINNING OF EXHIBITS.
________________________ ______________________
________________________
DESIGNATION
…………………..LOCATION……… __
… …..PURPOSE……..
Street Tree Planting
Area Along Street ROW
Public Tree Plantings
Street Yard Between Building
and Street Beautify Street
Street Wall Adjacent To Building Facing A Street Screen, Soften Building
Foundation Wall
Between A Building And A VUA
Improve Pedestrian Areas
VUA Interiors Islands, Medians, Bays,
Bio-swales Shade Pavements
& Cars
VUA Screen
Between Cars And Conflicting Land Use Screen Vehicles From View
Side Yard Buffer Buffering Conflicting Land Use At
Side
Screening Neighbors
Rear Yard Buffer Buffering Conflicting Land Use At Rear
Screening Neighbors
Habitat Preservation
Area Wetlands, Tree
Groves or Forest Protect Sensitive Land
Irrigation
Hydro-zones Site Irrigation
Conservation Zones Reduce Water
Waste
Stream Bank Buffer Separate Development and
Stream Filters Storm Water
__________________ ______________________
______________________________
Fig. 1.0 Geography of a Development Site,
Design Components
__________________________________________________________________
__________
Fig. 2.0 Typical Development Site Design
Components
__________________
______________________ ______________________________
STORM WATER BMP ……… ………..PURPOSE………… …………._______.
a) Micro-detentions Rain
Gardens to soak up rain water
b) Planted buffers Buffers along property edges
infiltrate water
c) French drains, infiltration
trenches Provide underground
storage of rain water
d) Sand filters
Clean contaminates from infiltration
e) Grassed swales or vegetated
ditches Filter, clean and slow run
off
f) Parking lot detention Capture oils,
grease, heavy metals
g) Porous paving Add
to permeability in paved areas
h) Underground storage
chambers Can be used to
detain or infiltrate run off
i) Irrigation cisterns Used to
disconnect rooftops, feed irrigation systems
j) Retained natural wetlands Absorbs storm water, many other natural
values
k) Preserved forest floor Absorb storm
water, many other natural values
l) Stream bank or riparian buffer Protect stream bank, buffer
development
__________________ ______________________
_________________________
Fig.
3.0
Recommended Storm Water BMP’s in the Louisiana Model Code
__________________________________________________________________
__________
Fig. 4.0 Typical Development Site Storm Water
BMP’s
NOTES
.
1. NAHB Research
Center, Inc., The Practice of Low Impact Development, U.S. Department of
Housing, Office of Policy Development & Research, Washington, D.C.
July 2003, pg 29
2. There are several
sources of good information about low impact development and storm water
management. They include Stormwater 360 (www.stormwater360.com),
the Low Impact Development
Center (www.lowimpactdevelooment.org)
and Path, Public Private Partnership For Advancing Housing Technology
(www.pathnet.org)
3. ________________,
National Menu of Best Management Practices For Stormwater Phase II, United States Environmental Protection Agency,
Washington D.C. nd.
http://cfpub.epa.gov/npdes/stormwater/menueof
bmps/menu/cfm
4. NAHB Research
Center, Inc., The Practice of Low Impact Development, U.S. Department of
Housing, Office of Policy Development & Research, Washington, D.C.
July 2003, pg 31-44
5. Study conducted for
the Louisiana Department of Environmental Quality for the EPA by Abbey
Associates, Inc, Landscape Architects – Planners, Baton Rouge
– New Orleans, Louisiana 2005-2006. Visit the web site at www.abbey-associates.com/splash-splash
6. The Landscape
Ordinance Research Project at Louisiana
State University
has conducted studies of landscape and tree laws since 1987. Visit their web
site that provides useful information about community landscape codes, code
vocabulary, design components, and technical standards. Visit LSU at www.greenlaws.lsu.edu.
7. The USDA Forest Service makes available a data base of tree
ordinances which is found on the Urban Forestry South Expo web site at http://www.urbanforestrysouth.org/Resources/Ordinances.
This is a searchable data base that is organized by subject and keyword.
8. See the attached
Outline To The Model Code, prepared by Abbey Associates,Inc. Landscape
Architects – Planners, Baton Rouge – New Orleans, Louisiana for
the State of Louisiana,
Department of Environmental Quality, 2005-2006. Additional information
available from Louisiana DEQ.
BACKGROUND
READING ON GREEN LAWS
Abbey, D.G. Buck, "Green Laws, Building Landscapes
In The Twenty-first century". Proceedings
1999 ASLA Annual Meeting, American Society of Landscape Architects, Washington D. C.. 1999.
Abbey, D.G. Buck, "Green Laws In Three
Communities". Proceedings 2003
National Urban Forest Conference, American
Forest, Washington D.
C.. 2003.
Abbey, D.G. Buck, "U.S. Landscape
Ordinances". John Wiley & Son,
Inc., New York, NY. 1998.
Abbey, D.G. Buck, "Guide To Writing A Landscape
Ordinance". Louisiana Association of Nurserymen, Baton Rouge, LA.
1988.
Abbey, D.G. Buck, "Guide To Writing A City Tree
Ordinance". Louisiana Association of Nurserymen, Baton Rouge, LA.
1993.
Bernhardt, E.A. and Swiecki, T.J., Guidelines for
Developing and Evaluating Tree Ordinances, California Department of Forestry
and Fire Protection Urban Forestry Program, Sacramento, CA. 1991.
Bowen, C., Landscape Ordinances: To Define and Protect,
Zoning Practice, American Planning Association, April 2004.
Fazio, James., How To Write A Municipal Tree Ordinance,
Bulletin No. 9. National Arbor Day Foundation, Nebraska City, Nebraska.
1991.
Garber, Melvin., Components of a Tree and Landscape
Ordinance, University
of Georgia, November,
2000.
Duerksen, Christopher. J., Richman, Suzanne, Tree Conservation Ordinances, PAS Report
Number 446, American Planning
Association, Chicago, Il. 1993.
Duerksen, Christopher. Tree And Vegetation Conservation
Ordinance Annotated Outline, Citizens For A Scenic Florida,Jacksonville, FL. 2002.
Moll, Gary, Ebenreck, Sara., Shading Our Cities, Island
Press, Washington D.C., 1989.
Robinette, Gary, O. "Local Landscape
Ordinances." Agora Communications, Plano,
Texas, 1992.
Wolfe, K.L., Trees, Parking and Green Law: Strategies
For Sustainability, College
of Forest Resources,
University of Washington,
Seattle, WA.
2004
__________________., International Zoning Code,
International Code Council Inc., Country
Club Hills, IL, 2002.
__________________., Manual For Hurricane Resistant
Construction, Southern Building Code Congress International, Birmingham, Alabama,
1993.
__________________., Standard Building Code, 1997
editon, Southern Building Code Congress International, Birmingham, Alabama,
1997.
Biography
D.G. ‘Buck’
Abbey is Associate Professor of Landscape Architecture at LSU and Principal of
the Louisiana,
landscape architecture - planning firm, Abbey Associates, Inc. He has taught
design, construction, graphics and computer technology courses at LSU since
1974. Abbey received his terminal degree from Harvard University. He is a recognized authority on municipal
landscape codes and is author of the book U.S.
Landscape Ordinances published by John Wiley & Sons, Inc. in 1998. He provides consulting services on landscape
codes and site planning nationwide.
________________ _____
____________
______________________________ ____
Research
for this presentation and this article have been made possible in part by
grants from the USDA Forest Service,
Urban and Community Forestry Program
of the Louisiana Department of Agriculture And Forestry , The Louisiana
Department of Environmental Quality and Environmental Protection Agency.
Appendix A - Standard Tree and Landscape Ordinance
Vocabulary
The following are technical terms that are commonly found in well
crafted contemporary tree and landscaped ordinances. The definitions are
attributed to public documents from the communities cited in the definition. (7)
___________________________________________________________
Arboricultural Treatments. Arboricultural
treatments" means all services, treatments or operations involving
trimming, pruning, spraying, injecting, fertilizing, cabling, surgery work,
removal of and cutting above or below ground level of a
tree…………………………………………………………………….
Missoula, Montana
Arborist, Certified. One who is well-versed in the art of
arboriculture, including tree surgery, the prevention and cure of tree
diseases, and the control of insects, and who has International Society of
Arboriculture (ISA) Arborist Certification……………………………………………….….
Miami-Dade, Florida
Buffering. The use of
landscaping along with berms, walls or decorative fences that at least
partially and periodically obstruct the view from the street…………..
Austin, Texas.
Caliper Means the minimum trunk diameter of a
replacement tree as measured at a predetermined point of measurement. Trunk
diameter for trees up to four inches is to be measured six inches above the
soil line. All trees over four inches in diameter will be measured 12 inches
above the soil line. …………..……………………….
Volusia
County, Florida
Canopy Cover. Means the area above
ground which is covered by the trunk and branches of the
tree…………………………………………………………………
Tigard,
Oregon
Critial Root
Zone,CRZ, The area of tree roots
within the crown dripline, this is generally defined as a circle with a radius
extending from the tree trunk to a point no less than the farthest crown
dripline………………….…....................................
Columbia, South Carolina.
Crownspread. Means
the distance from the ends of the branches on one side of the tree, through the
trunk, to the ends of the branches on the outermost branches on the other
side……………………………………………………………………..
Germantown, Tennessee
DBH. Refers to ‘diameter at breast height’ which means
the diameter of the trunk, at its maximum cross section, measured 54 inches (4
1/2 feet) above mean ground level at the base of the trunk..
………………………………………………………
Ashland, Oregon
Density
Factor For The Site, DFS. A unit of measure to
prescribe and calculate required tree coverage on a site based upon tree
size………………………………
Columbia, South Carolina
Dripline Area. Means the area within X
distance from the perimeter of the trunk of the tree at four and one-half feet
above natural grade where X equals a distance ten times the diameter of the
truck as measured four and one-half feet above natural
grade……………………………………………………….………………………….
Palo Alto, California
Impervious
Surface Percentage. An site intensity measurement of the
impervious surface of a building site. .......................................................................................
West Lafayette, Indiana.
Habitat
Preservation Area, HPA. An area
of a site in which the entire natural habitat is unchanged and protected for
the preservation of trees, storm water infiltration or wildlife.
………………………….………………………………….
Louisiana State University
Hatracking. The flat cutting of the top of a tree,
severing the leader or leaders, or the removal of any branch three inches or
greater in diameter at any point other than the branch collar, i.e., that point
where the lateral branches meet the main trunk………………………………………………………………..
Miami-Dade, Florida
Hazard or
Hazardous. Means a tree or part of a tree that has a high potential for
failure and falling on a nearby object because of dead or dying branches, roots
or trunk……………… …………………………………………………………………
Passadena, California
Heritage
and Specimen Planting. Shall mean any tree, grove, shrub, hedge or
other planting which is determined to have special significance to the
community……….
Milpitas, California
Land
Altering Activity. Any change to existing land which would
physically alter the existing conditions and vegetative cover on the
land...........................................
Shreveport, Louisiana.
Landmark Trees. Tree or trees as defined on
a list of trees enunciated and established by the Bedford Town Board, with such
list being filed in the office of the Bedford Town
Clerk…………………………………………………………………
Bedford, New
York
Net Lot Area.
The area within lot boundaries of all lands comprising the building
site............................................................................................................................
Miami-Dade County, Florida.
Opacity. An imaginary
vertical plane extending from the established grade to a required height of
which a required percent of the vertical plane shall be visually screened from
adjacent property use.... …………………………...........................
Dublin, Ohio.
Percent
Minimum Canopy. The amount of existing tree canopy an
Applicant must preserve based on the zoning designation of the land to be
developed………
Fayetteville, Arkansas
Perimeter
Landscape Strip. Is a landscaped area which separates the
vehicular use area from adjoining property and/or public right-of
way.....................................
Little Rock, Arkansas.
Plantable
Area: The pervious surface area
expressed in square footage available for the preservation or planting of
vegetation..................................................................
Alpharetta, Georgia.
Prohibited Tree Species. Those tree
species that are detrimental to native plants, native wildlife, ecosystems,
human health and/or safety and welfare.
This article incorporates by reference the Miami-Dade County Landscape
Manual listing of prohibited species…………………………………………………………………….
Miami-Dade, Florida
Protected
Tree. All mangrove trees and
cypress trees, regardless of diameter, shall be defined as protected
trees………………………………………………………….
Tampa, Florida
Protective Barrier means a
physical structure limiting access to a protected tree, composed of wood or
other suitable materials, which ensures compliance with the
intent of this
article………………………………….………………………………..
Biloxi, Mississippi
.
Public Trees. shall include all shade and ornamental trees or shrubs now or
hereafter growing on any street, park or public place………………………………
Portland, Maine
Reforestation. Means the establishment, in accordance with
the Howard County Forest Conservation Manual, of new forest cover to replace
forest resources lost because of development activities……………...……………………………………
Howard County, Maryland.
Riparian Buffer. A biological community consisting of trees, woody
shrubs and groundcover that exists along the banks of rivers, creeks or
intermittent and perennial streams…………………………….………………………………………
Fayetteville, Arkansas
Significant Tree. Significant
tree shall be any tree that is at least six (6) inches in
D.B.H…………………………………………...……………………………………..
Lynnwood,
Washington
Street Trees.
Street trees are herein defined as trees, shrubs, bushes,
and all other woody vegetation on land lying between property lines on either
side of all streets, avenues, or ways within the City………………...…………………………………..
Municipal Tree Manual (MTM)
Street
Yard. The street yard is the area of a lot which
lies between the street right-of-way line and the actual front wall line of the
building............…...........................
Austin, Texas.
Topping.
Topping is defined as the severe cutting back of tree limbs to stubs larger
than three (3) inches in diameter within the tree's crown to such a degree so
as to remove the normal canopy and disfigure the tree……………………………………
Georgia Framework Ordinance, Georgia
Forestry Commission
Tree And Landscape Commission. Shall consist
of nine (9) voting members
and several non-voting
ex-officio members who shall be appointed by the Mayor-President with the
approval of the Metropolitan Council and whose duties shall be to study of
problems involving the City-Parish’s urban forest, determine needs, compose and
annually review a City-Parish Urban Forestry Management Plan, and seek ways to
implement needed work…………………………………………………
Baton Rouge, Louisiana
Tree
Bank. A tree bank fund is
established by the City to provide an
opportunity to make a cash payment to
the City in lieu of providing required
landscape material.
…………………………………………………………….
Altamonte Springs, Florida.
Tree-Class
A. Any self supporting woody plant of a species
which normally grows to an overall height of at least fifty (50)
feet.……………….....................................
Covington, Louisiana.
Tree-Class
B. Any self supporting woody plant of a species
which normally grows to an overall height between thirty (30) and
fifty (50) feet…...................................
Covington, Louisiana.
Tree-Class
C. Any self supporting small tree or large shrub
of a species which normally grows to an overall height between fifteen (15) and
thirty (30) feet…......
Covington, Louisiana.
Tree Conservation Area, TCA. A Tree
Conservation Area is one or more areas
of a site which includes existing trees and their critical root zones. The
purpose of the TCA is to encourage the preservation of healthy trees that are
four (4) inches or greater in diameter at breast height………………….………………………………
Greensboro, North, Carolina
Tree Cover Requirements. All developments requiring submission and approval
of a site plan shall include the preservation and planting of trees on the site
to the extent that, at maturity of ten years, minimum tree cover s(10-20% of
site) shall be provided……………………………………………..……………………………….
Fairfax, County, Virginia
Tree
Density Unit (TDU). A credit assigned to a tree, based on the
diameter of the tree, in accordance with tables contained in this
ordinance…………………………. Gwinnett County,
Georgia.
Tree Density
Standard (TDS) : The
minimum number of Tree Density Units per acre which must be achieved on a
property after development..................................
Gwinnett County, Georgia.
Tree Permit . Consent given in
writing by the Urban Forester to a person , firm or agency
to alter or remove any tree or to do anything that would affect that City -owned or controlled tree,
including cutting or filling the soil around the roots, or allowing any toxic
pollutant to injure the tree………….……………………………
Raleigh, North Carolina
Tree
Preservation and/or Replacement Plan. A plan that identifies Tree Protection Areas
where existing trees are to be preserved and where proposed replacement trees
are to be planted on a property to meet minimum requirements, as well as
methods of tree protection to be undertaken on the site and other pertinent
information.
............................................................................................................
Gwinnett County, Georgia.
Tree
Protection Area (TPA) : Any
portion of a site wherein are located existing trees which are proposed to be
preserved …………................................................
Gwinnett County, Georgia.
Tree removal. means removal of a tree(s) or vegetation, through either direct or indirect
actions including, but not limited to, clearing, topping or cutting, causing
irreversible damage to roots or trunks; poisoning; destroying the structural
integrity; and/or any filling, excavation, grading, or trenching in the drip
line area of a tree which has the potential to cause irreversible damage to the
tree, or relocation of an existing tree to a new planting location.
………………………………………….
.Seattle, Washington
Tree
Survey. A plan drawing that
provides legend details about the location
and details of trees. and contains the information set
forth in Schedule “B” hereto.
Southlake, Texas
Tree Technical Manual. Means the regulations issued by the city manager to
implement this chapter………………………………...………………………….
Palo Alto, California
Vehicular
Use Areas. All areas subject to vehicular
traffic.....................................
San Diego, California.
Visual
Screen. A physical obstruction used to separate two
areas or uses which is at least 75 percent
opaque.…………………………..................................................
North Lauderdale, Florida.
Water Harvesting: Any combination of techniques that results in storm or flood
waters captured on
site, for later plant use or return to the water
table.........………………………………...................................................................
Sparks, Nevada.
Waterfront
Yard. Property abutting open water, bays, bayous,
wetlands, lakes, canals, aquatic conservation or preservation
areas.....................................................
Tampa, Florida.
Appendix B
- Standard Landscape Code
Vocabulary
The following are technical terms that are commonly found in well crafted
contemporary tree and landscaped ordinances. The definitions are attributed to
public documents from the communities cited in the definition.
LSU Landscape Ordinance Research Project
LANDSCAPE CODE VOCABULARY
“the geography of a development site”
c. 2003
all rights reserved.
ADA Spaces. Site spaces, defined by the Americans
With Disabilities Act, which must be barrier free. ADA spaces must be of a certain size,
location, gradient, surfacing and use. Often found in parking lots and near
building entries
Buffering. The use of landscaping or retained native
vegetation or the use of landscaping along with berms, walls or decorative
fences that at least partially and periodically obstruct the view from the
street or an abutting property in such a manner that vehicular use areas,
parking lots, parked cars, detention ponds and conflicting activity areas will
be partially or completely screened.
Bufferyard. A landscaped area usually at the side or rear
of development sites which are provided to separate and partially obstruct the
view of adjacent land uses or properties.
Foundation
Area. A proscribed area of ground immediately
adjacent to a building wall.
Heavy
Vehicle Loading Area. A paved area
designed to accommodate the maneuvering, loading and unloading, and parking of
commercial vehicles having extra length and excessive weight which may require
an increase in pavement depth or ability to carry heavy loads.
Hydrozone. A portion of the landscaped area having
plants with similar water needs that are served by one irrigation valve and a
set of head with the same schedule of water flow and timing.
Impervious
Surface:
Land area covered by a surface treatment that hinders the ability of the
underlying soils to percolate water.
Island. In road and parking area design, one of
several types of a raised planting area, usually curbed, and placed to guide
traffic, separate lanes, limit paving (impervious surface), preserve existing
vegetation and increase aesthetic quality.
Light
Vehicle Loading Area. A paved area designed
to accommodate the maneuvering, loading and unloading, and temporary parking of
commercial vehicles.
Drive
Through. A paved extension of a vehicular use area
whose sole purpose is allow for the pick up of deliver of goods.
Loading
Areas. An area which contains trash collection areas
of dumpster type refuse containers, outdoor loading and unloading spaces,
docks, outdoor shipping and receiving areas, outdoor bulk storage of materials
or parts thereof, and outdoor repair areas of any service stations, safety
equipment, inspection stations, or dealers.
Native
Plant Community: A natural association of
plants dominated by one or more prominent native plant species growing in its
natural habitat.
Habitat
Protection Areas, HPA. An area identified
on an approved site plan containing native vegetation, natural features or
unique habitat which will remain undisturbed when the property is fully
developed.
Open
Space. the unoccupied portion of a lot or building
site that is open to the sky and which may or may not contain landscaping,
landscaping structures, or garden facilities..
Outdoor
Storage Area. An uncovered area used for storage of
equipment, materials, goods, and supplies including the keeping of automobiles,
trucks, boats, trailers, buses, and lawn and garden equipment which are not
enclosed within building walls.
Parking Bay. A defined number of
parking stalls separated by interior landscape islands, plantings or shade
trees.
Parking
Lot Screen or VUA Landscape Strip. Is a
landscaped area which separates the vehicular use area of any development site
from adjoining property and/or public right-of-way and whose purpose is to
enhance the visual appearance of the site and to provide screening of the
vehicular use area and certain other activities.
Permeable
Pavement. An area of a vehicular use area paved with
material that permits water penetration into the soil. Permeable pavement may consist of any porous
surface materials which are installed, laid or poured.
Pervious
Area. The area of a development site remaining
after the area of structures, vehicular use areas, storage areas, utility
areas, access ways, pedestrian pavement or wet retention ponds are subtracted.
Protected
Tree.
A tree of a certain size, species, age or character which can not be removed
from a development site without a tree
removal permit.
Retention
Area:
Areas designed usually by hydrological calculations and used for the permanent
storage of storm water runoff. Micro-retention areas are sculpted minor
depressions, swales and irregularly shaped parts of a building site whose
purpose is to interrupt, slow and allow the seepage of storm water into
landscape beds or directly into the ground.
Detention
Area:
An area designed by hydrological calculations for the temporary storage of a
determined quantity of water with a release rate that is either fixed or
variable.
Sign
Monument Zone:
An area of a site dedicated or permitted to the erection of a permanent sign or
sign cluster often lighted and planted with low brightly colored seasonal
flowers.
Sight
Triangle. The area on either side of an access way at
its junction with a public street forming a triangle within which clear
visibility of approaching vehicular or pedestrian traffic must be maintained.
Storage
Area. Any exterior of a site which is used for the
keeping of garbage or trash cans, dumpsters, newspaper containers, oil and
bottled gas tanks, swimming pool equipment, air conditioners and mechanical
appurtenances.
Stream
Bank Buffer. This is a setback zone along a active bayou, creek, stream, river or
other water course which is left in its natural state for the purpose of
preventing sedimentation or pollution from finding it way into a public water
supply.
Street
Tree Planting Area. The street tree
planting area is the area of a development site that lies between the street
right-of-way line and the edge of the street curb parallel to the street. This land is publicly owned but is often used
for street tree planting, public utilities and street maintenance. It may also
include public space within the center of boulevard medians fronting
development sites.
Street
Wall. A space to be planted of a proscribed
dimension attached to the building wall fronting a public street.
Street
Buffer. An area with a defined depth which is
attached to a front property or servitude line which lies between the street
right-of-way line and the actual front wall line of the building facing a
public street. A variant is the preserved street buffer in which all native
trees of a certain size must be preserved.
Street
Yard. The street yard is the area of a lot, which
lies between the street right-of-way line and the actual front wall line of the
building facing a public street.
Technical
Standards.
Criteria, requirements and standards of a technical nature, usually specified
in quantities, dimensions, sizes, qualities and performance outcomes and spelled out in a landscape ordinance to guide
designers in the proper design of various parts of the development site,
building lot or property.
Travel
Lane.
The main access way, one way or two way, which serves a vehicular use area or
parking lot.
Tree
Protection Area (TPA) : Any portion of a site
wherein are located numerous existing trees and other native plant materials
which are proposed to be preserved.
Tree
Protection Zone. The area,
at the base of a tree, where the root zone is protected, from any of a
number of harmful activities.
Utility
Service Area:
An area which contains any surface mounted HVAC equipment, utility boxes,
booster stations, switch boxes, irrigation controllers and transformers that
are part of a site utility system.
Vehicular
Use Areas. All areas subject to vehicular traffic
including access ways, driveways, loading areas, service areas, and parking
stalls for all types of vehicles. Commonly thought of as parking lots,
driveways and interior streets.
Visual
Screen. A physical obstruction, partially opaque,
consisting of living plant material, natural or manmade construction material,
or a combination thereof used to visually separate two areas of a building
site.
Yard
Area. That portion of any building site covered by
the front, side and rear yard areas as established by the minimum setback
requirements of a zoning ordinance.
Yard,
Waterfront. A waterfront yard is the yard adjacent to
public waterways. Waterfront yards front bays, bayous, wetlands, lakes, canals,
aquatic conservation areas, aquatic preservation areas and similar waterways.
ADMINISTRATIVE TERMINOLOGY
Administrative
Standards:
The set of rules, procedures and requirements set forth in a landscape code for
both public administrators, consultants, builders, developers or contractors
associated with making permit application, assembling materials for pubic
review, meeting the requirements of the landscape or tree regulations, seeking
approvals, enforcement, conducting site inspections, collecting fees, issuing
permits and filing reports.
Comprehensive
landscape code or land alteration code.: Very sophisticated ordinances, codes
that regulate not only landscaping but
land alteration, tree protection, tree removal, storm water management,
erosion control, ground water recharge and land clearing and habitat
preservation.
Landscape
Administrator. A professionally
educated or trained and licensed person who is responsible for advanced
technical and supervisory work in the enforcement of Landscape regulations.
Work involves supervising and coordinating landscape inspection and plan review
work, reviewing peer professional prepared landscape plans and specifications
and writing administrative reports and giving expert testimony in regards to
site development.
Landscape
Architect. Professionally
educated and licensed designer who is authorized to prepare landscape plans,
specifications and provide expert testimony in regards to site development and
compliance with municipal landscape regulations.
Landscape Inspector. Technical municipal employee, whose work
involves on-site inspections for landscaping of new construction sites and older
existing sites to ensure landscape code compliance. Generally reports to the
Landscape Administrator.
Design
Components.
Sections of a landscape ordinance that make reference to specific parts of a
site, building lot or development property that must be designed using
standards, specifications or technical requirements specified in that
ordinance.
Design
Manual:
A companion document to a landscape code which is prepared to summarize the
technical language of a landscape code or tree regulations and the
administrative procedures involved with preparing landscape design plans,
seeking building permits, tree removal permits, land alteration permits
conditional use of property.
Design manuals generally contain information
that is helpful to designers such as a description of design components,
technical standards and administrative procedures included within the landscape
code. Design manuals often contain
formulas, tables, diagrams, typical construction details, materials lists,
standard specifications and helpful appendix material. Design manuals are written in easy to
understand language and illustrated with graphics so that city officials,
permit applicants and property owners can under stand the technical landscape
architecture, construction, horticulture and forestry terms contained within
the landscape ordinance.
Green
Law.
This is a sobriquet for the term landscape ordinance or any site specific law
that preserves, protects or enhances natural systems on a defined parcel of
land or zoned development site. Common
green laws include post construction landscape ordinances, tree preservation
ordinance and land alteration ordinances whose prime purpose is the protection
of native habitat including vegetation, soils, natural drainage and wildlife.
Published with permission of John Wiley & Sons publishers of Abbey, Buck, U.S.
Landscape Ordinances, John Wiley, NYNY, 1998.
Landscape
Code:
Created as a result of a landscape ordinance to create and a set forth of set
of technical landscape standards and responsibilities which are included within
a municipal zoning ordinance to ensure that the public health, safety, and
welfare is protected in regards to the development of land and changes to
natural systems such as vegetation, soil, water, climate and wildlife
associated with such land.
Landscape
Ordinance:
A public law, requiring public review and approval of a permit and creating a
landscape code or tree regulations, often contained within a zoning ordinance
or land development code that regulates landscape design, landscaping,
landscape installation, horticultural practices, tree removal, planting, care
and general site maintenance.
Landscape
Code Standards.
These are specifications, requirements, quality determinations or performance
guidelines for judging acceptable compliance with the provisions of a landscape
code.
Landscape
Plan. The preparation of graphic and written criteria,
specifications, and detailed landscape plans to arrange and modify the effects
of natural features such as plantings, ground and water forms, circulation,
walks, irrigation, landscape lighting, erosion control, on site drainage and
other features to comply with the provisions of a community landscape code.
Low Impact Development Strategies, a series of actions
and activities that mimic pre-development site conditions that can be used to
treat on-site storm water within planting areas that are used for buffers,
screens, street yards, site open space and parking lot interiors while at the
same time reducing the need for expensive traditional storm water collection
and conveyance systems.
Permit. An official public document issued to a
contractor or developer that authorizes performance of a specific regulated
activity on a development site.
Post Construction Certification Statement: A statement that is
filed with municipal officials by the landscape architect certifying that all
landscape construction has been implemented according to the requirements of
the landscape ordinance or any public law that may apply.
