urban coastal greenway design manual

Design Manual

Photo © Save The Bay

For the Metro Bay RegionCranston, East Providence, Pawtucket, and Providence

Urban Coastal Greenway

This publication is available from the Rhode Island Coastal Resources Management Council, Stedman Government Center, 4808 Tower Hill Road,Wakefield, RI 02879, and on-line at www.crmc.ri.gov/samp.

Portions of this document have been taken from The Urban Environmental Design Manual. (2005). R. Claytor. Providence: R.I. Department ofEnvironmental Management; LID Design Techniques. (2005). Prince George�s County, Md.; B. McRae, C. Sweeney, and Y. Kawaguchi. ShorelineSpaces: Public Access Design Guidelines for the San Francisco Bay. (2005). San Francisco Bay Conservation and Development Commission; andJ. LaClair, B. McCrea, and Hunt Design Associates. (2005). Shoreline Signs: Public Access Signage Guidelines. San Francisco Bay Conservationand Development Commission.

This document should be referenced as: Urban Coastal Greenway Design Manual for the Metro Bay Region. (2007). J. McCann, S. Menezes, G.Fugate, C. Chaffee, J. Boyd, and M. Allard Cox (eds.), Rhode Island Sea Grant, Narragansett, R.I. 62 pp. This publication is sponsored by the RhodeIsland Coastal Resources Management Council (CRMC), under NOAA Grant No. NA03NOS4190100. CRMC is a state agency dedicated to thepreservation, protection, development, and restoration of coastal resources for all Rhode Islanders. This publication is also sponsored in part byRhode Island Sea Grant under NOAA Grant No. NA16RG1057. The views expressed herein do not necessarily reflect the views of CRMC, NOAA, orany of its sub-agencies. The U.S. Government is authorized to produce and distribute reprints for governmental purposes notwithstanding any copy-right notation that may appear hereon.

September 2007

Acknowledgements

Foreword

100. Introduction

200. Sustainable Landscaping

300. Stormwater Management

400. Public Access in the Urban Coastal Greenway

Appendix I. Metro Bay Shoreline Signs

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Table of ContentsUrban Coastal Greenway Design Manual

Technical Committee:

· Robert Ballou, Chief of Staff, R.I. Dept. of Envi-ronmental Management (RIDEM)

· Jon Boothroyd, University of Rhode Island (URI)Quaternary Geology Professor and R.I. StateGeologist

· Thomas Boving, URI Geosciences Assistant Profes-sor

· Jeanne Boyle, Planning Director, City of EastProvidence

· Michael Cassidy, Planning & Redevelopment Direc-tor, City of Pawtucket

· Thomas Deller, Director of Planning and Develop-ment, City of Providence

· Kristen Fletcher, Roger Williams University (RWU)/Rhode Island Sea Grant Legal Program Director

· Grover Fugate, Executive Director, R.I. CoastalResources Management Council (CRMC)

· Wilfred Gates, Principal Landscape Architect, Gates,Leighton & Associates, Inc.

· Arthur Gold, URI Natural Resources SciencesProfessor

· Terrence Gray, RIDEM Assistant Director for Air,Waste & Compliance

· Roberta Groch, former Senior Planner, City ofProvidence

· Jennifer McCann, Extension Leader for CoastalPrograms, Rhode Island Sea Grant/URI CoastalResources Center

· Sunshine Menezes, Executive Director, MetcalfInstitute for Marine and Environmental Reporting

· Fred Presley, former RIDEM Sustainable Water-sheds Office Staff

· Jared Rhodes, Planning Director, City of CranstonPlanning Department

· Eric Scherer, National Resources ConservationService (NRCS), Conservationist

· Colgate Searle, Rhode Island School of Design,Professor of Landscape Architecture

· Michael Walker, R.I. Economic Development Corp.,Project Manager

· Lance Young, RWU/Rhode Island Sea Grant LawProgram, Fellow (2004 � 2006)

Other individuals who provided technical expertise:

· Ken Anderson, Supervising Civil Engineer, CRMC· Thomas Andolfo, Andolfo Appraisal Associates,

Inc.· Lucy Auster, Program Manager, King County (WA)

Solid Waste Division· Jane Austin, Director of Advocacy & Policy,

Narragansett Bay/Save The Bay· Robert Azar, Senior Planner, City of Providence· Daniel Baudouin, Executive Director, The Provi-

dence Foundation· Jim Boyd, Coastal Policy Analyst, CRMC· Charles Cannon, Rhode Island School of Design

Adjunct Professor of Architecture· Caitlin Chaffee, Coastal Policy Analyst, CRMC· Kimberly Cole, Environmental Scientist, Delaware

Coastal Programs· Craig Denisoff, President, National Mitigation

Banking Association· Bruce DiGennaro, Managing Partner, Principal

Environmental Planner, Essex Partnership· Steven Dylag, Keystone Consulting Group, Inc.· Omay Elphick, former Policy Specialist,

Narragansett Bay/Save The Bay· Laura Ernst, Environmental Consultant, Environ-

mental Science Services, Inc.· Diane Feather, Senior Planner, City of East Provi-

dence

Thanks to Technical Committee members and individuals who provided technical expertise in thedevelopment of the Metro Bay Urban Coastal Greenway Policy and Design Manual

ACKNOWLEDGEMENTS

· Michael M. Tikoian, Chairman· Paul E. Lemont, Vice Chair· Thomas Ricci· David Abedon· Donald Gomez· K. Joseph Shekarchi

· Neill Gray· W. Michael Sullivan, Director RIDEM· Raymond C. Coia· Gerald P. Zarrella· Bruce Dawson

R.I. Coastal Resources Management Council members:

· Wenley Ferguson, Habitat Restoration Coordinator,Narragansett Bay/Save The Bay

· John Flaherty, Director of Research & PublicInformation, Grow Smart Rhode Island

· Jennifer Flanagan, Keystone Consulting Group, Inc.· Kevin Flynn, Associate Director, Planning Division,

R.I Dept. of Administration· Janet Freedman, Coastal Geologist, CRMC· Marion Gold, URI Director of Cooperative Exten-

sion Education Center· Elizabeth Greenleaf, former Rhode Island School of

Design Instructor· Janice Greenwood, Environmental Consultant,

Environmental Science Services, Inc.· John Greer, Maryland Sea Grant College Program,

Assistant Director, Communications & PublicAffairs

· Peter Groffman, Associate Scientist, Institute ofEcosystem Studies

· Janice Hannert, FRE Building Company, Inc.· Emilie Hauser, Coastal Training Coordinator,

Hudson River National Estuarine Research Reserve· Barney Heath, Senior Planner, City of Pawtucket· Leo Hellested, RIDEM Chief of Waste Manage-

ment· Johanna Hunter, Grant Specialist, U.S. Environmen-

tal Protection Agency· Robert Johnston, University of Connecticut Sea

Grant College Program, Associate Director· Scott Lajoie, Vice President, Commercial Real Estate

Group, The Washington Trust Company· CJ Lammers, Supervisor, Environmental Planning

Section, Maryland-National Capital Park and Plan-ning Commission

· Andrew Lipsky, NRCS, Biologist· Christopher Littlefield, Manager, The Nature

Conservancy, Block Island Office· Kelly Mahoney, Policy Analyst, R.I. Senate Policy

Office· Susan Mara, Planner, City of Pawtucket· Brad McCrea, Bay Development Design Analyst,

San Francisco Bay Conservation and DevelopmentCommission

· Michael McMahon, former R.I. Economic Develop-ment Corp., Executive Director

· Scott McWilliams, URI, Natural Resources SciencesAssociate Professor

· Karen Metti, Manager, Boulder, Colorado,Greenways Program

· Numi Mitchell, The Conservation Agency, Biologist· Carolyn Murphy, RIDEM, Wetlands Manager· Doug Myers, Implementation Team Liaison, Puget

Sound Action Team· James Opaluch, URI Environmental and Natural

Resource Economics Professor· Kelly Owens, RIDEM Site Remediation Manager· John Parsons, North Carolina State University

Biological Agricultural Engineering Professor· Paul Pawlowski, Principal Architectural Consultant,

Pawlowski Associates, Inc.· Ken Payne, Policy Director, R.I. Senate Policy

Office· Jennifer Pereira, Executive Director,

Woonasquatucket River Watershed Association· Fern Piret, Planning Director, Maryland-National

Capital Park and Planning Commission· Lisa Primiano, RIDEM Land Acquisition & Real

Estate Manager· Rick Pruetz, Fellow of the American Institute of

Certified Planners· Dave Reis, Supervising Environmental Scientist,

CRMC· Robert Roseen, University of New Hampshire

Stormwater Center Director· Julia Slom, Senior Vice President, Commerical. Real

Estate Group, The Washington Trust Company· Curt Spalding, Executive Director, Narragansett

Bay/Save The Bay· Duncan Stuart, Critical Area Coordinator, City of

Baltimore Department of Planning· Steven Swallow, URI Environmental and Resources

Economics Professor· Anne Tate, Rhode Island School of Design Archi-

tecture Assistant Professor· Al Todd, Watershed Program Leader, U.S. Dept. of

Agriculture Forest Service· Timothy Tyrrell, URI Professor of Economics· Thomas Uva, Executive Director, Narragansett Bay

Commission· Katrina Van Dyne, former RWU/Rhode Island Sea

Grant Law Program Staff· Sandra Whitehouse, Environmental Policy Analyst,

R.I. House of Representatives Policy Office· Jeff Willis, Deputy Director, CRMC· Richard Youngken, Executive Director, The Dunn

Foundation

Urban Coastal Greenway Design Manual III

Foreword

detailed maps and other information.

DefinitionThe UCG begins at the inland edge of thecoastal feature, and its width is determined byits UCG Zone. With CRMC approval, appli-cants may utilize a buffer averaging method,where compensatory UCG width is providedin an area or areas in return for a necessaryreduction in UCG width in other areas of thesite, provided the total square footage of theUCG area remains the same.

Once the location of the UCG has been de-termined, a required construction setback of25 feet is measured from the inland edge ofthe UCG. The setback may be reduced whenthe applicant can clearly demonstrate that theproject and its subsequent use and mainte-nance will not result in the privatization of, orpreclude public use of, the UCG. The CRMCexecutive director may require additional set-back when site conditions warrant, especiallyfor areas susceptible to high erosion, to pro-tect coastal resources or public safety.

CompensationAnother novel component of the UrbanCoastal Greenway policy is an option to re-duce the UCG width through compensation.The compensation option generally allows anapplicant to reduce the UCG from the stan-dard width in return for site or coastal resourceenhancements such as improved public accessor habitat conservation and preservation.These options are described in Section 230of the policy.

This manualThis design manual is intended to assist appli-cants in meeting UCG requirements. It is nota regulatory document.

The Urban Coastal Greenway (UCG)Regulations for the Metro Bay Region are a new approach to coastal veg-

etative buffers for the urbanized environmentof northern Narragansett Bay. The UCGpolicy allows redevelopment of the Metro Baywaterfront in a manner that integrates eco-nomic development with expanded publicaccess along and to the shoreline, and providesfor the management, protection, and restora-tion of valuable coastal habitats.

Permit applicants in the Metro Bay area havea choice between following the coastal bufferand setback regulations as set forth in theRhode Island Coastal Resources ManagementProgram (RICRMP) or using the UCG policy,which clarifies and streamlines the regulatoryprocess for urban coastal development andallows greater flexibility in meeting the R.I.Coastal Resources Management Council(CRMC) requirements. The policy establishesstandards regarding overall vegetation of thesite, management of stormwater runoff us-ing Low Impact Development (LID) tech-niques, and public access. Four UCG Zones,each with its own requirements, have beenestablished within the planning boundary ofthe Metro Bay Special Area Management Plan(SAMP): Residential Zone, Area of ParticularConcern Zone, Inner Harbor and River Zone,and Development Zone. The boundaries ofthese zones have been determined by the ex-isting conditions of coastal habitat, publicaccess infrastructure, single- and two-familyresidential areas, and current municipal plansfor development and/or redevelopment. Therequirements for each zone are described inUCG Sections 160 through 190. Applicantsare encouraged to use the Metro Bay InternetMap Service (IMS) available online at:maps.provplan.org/sampmapper/ for more

THE METRO BAY URBAN COASTAL GREENWAY

Urban Coastal Greenway Design Manual 1

Introduction

110. URBAN COASTALGREENWAY PROGRAM

A. Vision

The Metro Bay region (Cranston, EastProvidence, Pawtucket, and Providence)is experiencing a major redevelopmentboom, and is poised to become a nation-ally recognized destination for urban liv-ing. Given this, regulations specific to theurban shoreline of northernNarragansett Bay were developed for theCoastal Resources Management Program(Redbook). While the Redbook requiresthat buffer zones be undisturbed and al-lowed to grow naturally so as to maxi-mize wildlife habitat and water qualitybenefits, an urban landscape requiresgreater flexibility in buffer design and main-tenance. It is still desirable to achieve the maxi-mum habitat and water quality benefits pos-sible within urban areas, but the design of ur-ban vegetative buffers must also acknowledgethe simultaneous goals of redevelopment andallowing usable urban green space with in-creased public access to the shoreline. In ad-dition, urban buffers require thoughtful de-

sign and maintenance if they are to achievewater quality goals in areas dominated by im-pervious cover.

The ultimate vision of the Urban CoastalGreenway (UCG) Program is the creation ofa continuous, sustainably landscaped, greencorridor along upper Narragansett Bay. Thisgreen corridor, or greenway, will protectcoastal resources and foster recognition of thenatural aesthetic value as well as the economicvalue of the Metro Bay shoreline. It will alsobe a direct link to the water for residents andvisitors and ensure a sustainable approach toshoreline development.

B. Goals

The UCG Program was designed to achievethree primary goals: increased public accessto the coast, complete on-site stormwatermanagement primarily through vegetativetreatments, and the preservation and restora-tion of the aesthetic value of Rhode Island�s

100. INTRODUCTION

Northern Narragansett Bay

Save The Bay coastal greenway

Urban Coastal Greenway Design Manual2

urban shoreline through sustainable landscap-ing. Although the federal mandate governingCRMC�s activities also calls for the consider-ation of additional coastal values and func-tions, CRMC recognizes that the use, size, andfinancial constraints of urban parcels requirea more focused and flexible approach tocoastal management. Therefore, the major re-quirements of this new approach toward ur-ban coastal vegetative buffers are:

1. Sustainable landscaping:

(a) Greenways shall be entirely vegetated, withthe exception of public access pathways. Thegreenway shall be planted with sustainablevegetation.

(b) Fifteen percent vegetation of the devel-opment. Each development site shall have veg-etative coverage of at least 15 percent of thesurface area within the site. The coverage shallconsist of sustainable vegetation, and may bemet by the greenway alone, or through a com-bination of the greenway and additionalplantings elsewhere on the property, includ-ing rooftops.

2. One hundred percent on-sitestormwater management:

One hundred percent of the stormwater shallbe managed on site. One hundred percentstormwater management is defined in section

Potential greenway corridor for northern Narragansett Bay

Woonasquatucket River


Introduction

300.6 of the Redbook. (www.crmc.state.ri.us/regulations/programs/redbook.pdf). CRMCapplicants must demonstrate that the pro-posed project will remove 80 percent of thetotal suspended solids (TSS) from the first oneinch of runoff, which, per the most recentversion of the Rhode Island Stormwater De-sign and Installation Standards Manual, canalso be defined as 100 percent removal of TSSparticles equal to or greater than 70 micronsin diameter (www.dem.ri.gov/programs/benviron/water/permits/ripdes/stwater/index.htm). This shall be accomplishedthrough low-impact-development (LID) treat-ments to the maximum extent practicable (e.g.,swales, bioretention areas, and green roofs).The use of LID techniques is also in agree-ment with the policies of the Narragansett BayCommission.

3. Continuous alongshore public accessand periodic arterial access:

The greenway shall include a continuousalongshore (primary) public access pathwayand at least one arterial (secondary) publicaccess pathway per development site.

120. WHY THIS DESIGNMANUAL?

A. Design Goals

The UCG Program is intended to help achieveseveral design goals:

1. Adherence to an urban design aesthetic thatshowcases the views of Narragansett Bay andthe Seekonk, Providence, Woonasquatucket,and Moshassuck rivers from the shoreline, aswell as the view of the shoreline from the wa-terways.

2. Use of a diverse mix of sustainable, low-maintenance vegetation throughout each de-velopment site, and especially within the UCG.This will allow aesthetic appeal, will providesome of the water quality benefits of a natu-ral vegetative buffer, and will protect somehabitat value for wildlife such as migratorysongbirds.

3. An infiltration approach to stormwatermanagement through the use of LID tech-niques.

130. HOW TO USE THIS DESIGNMANUAL

The Urban Coastal Greenway Design Manualapplies to all development proposals in theMetro Bay Special Area Management Planboundary. This manual is intended to providetechnical information, guidance, and addi-tional references for accomplishing the UCGrequirements. This manual is not a compre-hensive source for design options within theUCG. CRMC and its staff may clarify, inter-pret, and apply the guidelines in this manualas appropriate.

Bioretention areas Green roof on commercial building


Each section of the manual is organized ac-cording to the following outline:

100. Title of the chapter

This heading provides an introduction to thechapter subject, and a context for the UCGrequirements.

110. UCG Requirements

This section contains a description of the spe-cific requirements for the chapter subject inthe UCG regulations. This section should notbe used in place of the regulations document,but should be used as a brief summary of themajor requirements regarding each subject.

120. Meeting UCG Requirements

This section details techniques and strategiesto meet the UCG requirements, focusing onsustainable development technologies andmethods.

130. Hypothetical Plans

The graphics in this section illustrate examplesof appropriate design elements to accomplishspecific requirements within the UCG. Thesehypothetical plans are not prescriptive.

Clockwise from upper left: Slater Mill,Pawtucket; Conley�s Wharf, Providence;Stillhouse Cove, Cranston; Blackstone Park,Providence; Sabin Point Park, East Provi-dence


Sustainable Landscaping

210. UCG VEGETATIONREQUIREMENTS

A. Sustainably vegetated greenway

With the exception of certain low-impact de-velopment (LID) stormwater treatment facili-ties and approved public access pathways, ur-ban coastal greenways shall be designed asnative plant communities and/or sustainablelandscapes using, whenever possible or appro-priate, noninvasive native and/or sustainablespecies of vegetation. These species shall bechosen from the CRMC/University of RhodeIsland (URI) Coastal Plant List (www.crmc.ri.gov/pubs/pdfs/uri_plantlist.pdf) or another appro-priate list approved by CRMC. The plants onthis list have been selected for their minimalmaintenance requirements, habitat value, andability to survive in coastal environments. Ap-plicants should also refer to the Rhode IslandInvasive Species Council�s list of invasive plants( w w w. c r m c . r i . g o v / p u b s / p d f s /RI_invasives.pdf). Plants on this list will notbe allowed as part of a UCG landscape plan.

B. Fifteen percent vegetation ofdevelopment site

Applicants must maintain sustainable vegeta-tive coverage on at least 15 percent of the sur-face area within the development parcel. Thisvegetation requirement may be met by thegreenway, or through a combination of thegreenway and additional plantings elsewhereon the property. Allplanting plans shall beprepared by a licensedlandscape architect (seeR.I. Gen. Laws §5-51).When planning land-scape features that alsofunction as stormwatercontrols, be sure that thelandscape architect hasexperience with creatingplanting plans for such practices, and keep inmind that the design of stormwater manage-ment practices must be done by a licensedengineer. It is ideal to have professionals fromboth fields working together early on in the

200. SUSTAINABLE LANDSCAPING

This illustration shows that 15 percent vegetation can beachieved using green roofs, stormwater planters, and perme-able paving.

Stormwater planters aroundbuildings treat roof runoff.

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design process. The landscape plan shall usegroundcovers, understory plantings, grasses,forbs, shrubs, and trees appropriately toachieve the goals of these regulations. Theseplantings may include landscaping elementsor vegetated stormwater treatment practicessuch as green roofs and rain gardens. Withinthe greenway, the plantings should include amix of trees, shrubs, and ground covers, withminimal use of high-maintenance lawn sodsand grasses.

C. Preserve existing vegetation

Existing noninvasive vegetation (especiallytrees) shall be preserved in urban coastalgreenways whenever possible.

D. Maintain the greenway

The property owner with a UCG is respon-sible for maintaining the UCG.

CRMC requires the property owner to sub-mit a UCG landscape plan that includes thefollowing:

! Delineation of UCG boundaries! Photograph(s) of existing conditions! Property lines, easements, and utilities! Existing and proposed curbs, gutters,

sidewalks or pavement edges! Location, Latin and common names,

and caliper of existing native trees andother native woody vegetation

! Location and Latin and commonnames of vegetation to be removed

! Latin and common names and caliperof plants to be installed, their plannedlocations and spacing (include on planand as a separate list document)

! Planned grading or elevation changes! Hardscaping and any other planned

landscape features

! Representative cross sections oflandscaped areas

! Planned public amenities (parkingareas, pathways, etc.)

! Planned LID stormwater managementpractices

! Location of UCG signage

In addition, property owners submitting land-scape plans must include a maintenance planthat describes all landscape maintenance ac-tivities to be performed within the UCG.Activities addressed within the maintenanceplan should include:

! Pruning and removal of dead material! Leaf removal! Weeding and removal of invasive

species! Mulching! Irrigation! Fertilization! Pest management

For each activity, the maintenance plan shouldidentify the party responsible for that activity,as well as a detailed schedule of when and thefrequency with which the activity will occur.For maintenance of vegetated stormwatermanagement practices, see the StormwaterSection (Section 300) of this manual. Whencreating a landscape management plan, keepin mind the following recommendations:

Save The Bay chose a variety ofspecies for their stormwater manage-ment properties, habitat value, andminimal maintenance requirements.



Pruning and weeding

! Whenever possible use mechanicalmethods of vegetation removal (e.g.,mowing with tractor-type or pushmowers, hand cutting with gas orelectric powered weed trimmers)rather than applying herbicides. Usehand weeding where practical.

! Avoid loosening the soil when con-ducting mechanical or manual weedcontrol, as this could lead to erosion.Use mulch or other erosion controlmeasures when soils are exposed.

! Place temporarily stockpiled materialaway from watercourses, and berm orcover stockpiles to prevent materialreleases to storm drains.

Waste management

! Leaves, sticks, or other collectedvegetation should be disposed of byappropriate means as leaf and yardwaste. Do not dispose of collectedvegetation into waterways or stormdrainage systems.

! Place temporarily stockpiled materialaway from water bodies and stormdrain inlets, and berm or cover stock-piles to prevent material releases to thestorm drain system or water bodies.

! Minimize the use of high nitrogenfertilizers that produce excess growthrequiring more frequent mowing ortrimming.

! Avoid landscape wastes in and aroundstorm drain inlets by using baggingequipment or by manually picking upthe material.

Irrigation

! Keep landscape irrigation needs to aminimum through proper plantselection and placement. Properlysited native or sustainable plantsshould require minimal irrigation onceestablished.

! Whenever possible, utilize watercollected in stormwater managementpractices such as rain barrels andcisterns for landscape irrigation.

! Where irrigation is necessary duringplant establishment, utilize practicesand equipment that promote waterconservation, such as soaker hoses andmoisture sensors. In addition, placeplants in locations to which they aresuited (e.g. shady or sunny areas).Simply grouping plants with similarwater needs together will result inmuch more efficient water use. Refer

Fescues require little maintenance.

Selecting a variety of plants providesvisual interest while minimizing use ofturf.

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to the CRMC / URI Coastal Plant Listfor individual plant species character-istics and requirements.

Fertilizer and pesticides*

! Minimize fertilizer and pesticide useto the greatest extent possible throughproper plant selection and placement.Properly sited native / sustainableplants should require minimal inputsof fertilizer and pesticides onceestablished.

! Do not use fertilizers or pesticides ifrain is expected within the following24 hours. Apply fertilizers and pesti-cides only when wind speeds are low(less than 5 mph)

! Calibrate fertilizer and pesticideapplication equipment to avoid exces-sive application.

! Incorporate fertilizers into the soilwhere possible, rather than broadcast-ing onto the surface.

! After application, sweep fertilizerspilled on hard surfaces such aspavement back onto lawn surfaces(never hose it off). Do not sweepfertilizer into gutters or stormdrains.Use a fertilizer spreader with an�edgeguard� device. Alternatively, abuffer strip of plantings that won�trequire fertilizer should be used bydriveways or sidewalks.

! Periodically test soils to determinefertilizer needs.

! Utilize a comprehensive managementsystem that incorporates integratedpest management (IPM) techniques(visit the Northeastern IPM Center�swebsite at www.northeastipm.org forresources).

! Use pesticides only if there is anactual pest problem (not on a regularpreventative schedule).

! Do not mix or prepare pesticides forapplication near storm drains orwithin 50 feet of the shoreline or edgeof a surface water body.

! Prepare the minimum amount ofpesticide needed for the job and usethe lowest rate that will effectivelycontrol the pest.

! Employ techniques to minimize off-target application (e.g. spray drift) ofpesticides, including consideration ofalternative application techniques.

! Triple rinse containers, and use rinsewater as product. Dispose of unusedpesticide as hazardous waste.

! Dispose of empty pesticide containersaccording to the instructions on thecontainer label.

*Follow all federal, state, and local laws and regula-tions governing the use, storage, and disposal of fertil-izers and pesticides and training of applicators andpest control advisors.

220. MEETING UCG VEGETATIONREQUIREMENTS

A. Selection of greenwayvegetation

1. Select sustainable plants

When selecting plant materials for thegreenway, choose species listed in the URIGreen roof atop apartment building

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Coastal Plant List (www.crmc.ri.gov/pubs/pdfs/uri_plantlist.pdf). These plants havebeen selected for their ability to thrive incoastal environments, their habitat value, andminimal maintenance requirements. A list ofgrowers and suppliers can also be found onthe CRMC website.

2. Minimize turf

While turf may seem preferable from a main-tenance perspective, it can be problematic dueto its potentially large fertilization and waterrequirements, as well as its limited wildlifehabitat value. It is best to limit turf to areasreserved for picnicking or similar recreationalactivities that require lawn. When turf is used,select a low maintenance turf variety that isappropriate for the environment in which it isto be planted. The amount of use and levelof care must be considered when selecting thecorrect grass mixture for the lawn, and culti-vars should be selected that are disease, in-sect, and drought resistant. Avoid landscapedesigns that require long, narrow areas of turf,which are difficult to water efficiently, andinstead specify native ground covers from theCRMC/URI Coastal Plant List for these ar-eas.

Fertilizer and water use can be reduced by se-lecting the improved drought-resistant andlow-fertilizer requirement varieties of fescues,or newer drought-tolerant hybrid varieties ofKentucky bluegrass. Fine fescues are a groupof fescues including chewings, creeping red,and hard fescues. Fine leaf fescues performwell under low-maintenance situations andshould be considered for use when lookingfor a low-maintenance lawn grass. Tall fescueis another lower maintenance grass but doesnot perform as well as the fine fescues undervery low maintenance. A combination of turf-type, tall, and fine fescues is usually best. Seethe CRMC/URI Turf Protocol for SensitiveAreas for guidance in choosing the appropri-ate mix for your site.

3. Provide variety in landscape design

Variety can be achieved both through the se-lection of plants as well as in the design ofthe plantings.

! Focus UCG landscape design oncreating plant communities rather thanisolated specimen plantings. Placeplants that are found growing togetherin natural settings in dense groupings.

! Visual interest can be created withinthe greenway by incorporating avariety of plant forms (trees, shrubs,groundcovers) into the landscape.

! Site plants properly so that, whenmature, they complement rather thancompete with each other. See CRMC�sBuffer Zone Planting Guidelines forguidance on plant spacing and installa-tion. To provide a greenway that drawsinterest throughout the year, chooseevergreen trees, shrubs, vines, plantswith colorful bark or fruit, and peren-nials that keep their foliage or flowersthrough the winter. Small plantings of

Urban forests, such as this one in theMetro Bay area, provide habitat for avariety of species.


Benefits of incorporating trees within an Urban Coastal Greenwayand adjacent lands. Modified from Ryan et al. (2002), McPherson et al.(2001), and Cappiella et al. (2005).



annuals and bulbs can provide addi-tional color during the growingseason.

4. Cultivate wildlife habitat by selectingappropriate species

The careful selection of vegetation for thegreenway can offer the concurrent benefit ofproviding wildlife habitat, especially for mi-gratory birds. Consider the following guide-lines for promoting bird habitat within theUCG.

! Examine existing and proposedlandscaping in terms of promotinghabitat, especially for migratory birds.

! Design landscaping with plant speciesthat are bird friendly, i.e., provideshelter, nesting material, and foodsources (See the URI Coastal PlantList for plant species with wildlifehabitat value).

! Design multi-layered landscapes thatinclude perennials and groundcovers,shrubs, under-story trees, and canopytrees.

! Design water edges with aquatic andriparian species and natural wetlandand upland plantings.

! Design water supply for landscapemaintenance and necessary sources ofwater for birds.

! Design new facilities to eliminate orminimize hazards to migratory andnesting birds.

! Use construction techniques andmaterials that avoid or mitigate bird-adverse interactions, such as erosionnetting.

5. Cultivate Urban Forests

In addition to providing aesthetic value (Ryanet al., 2002), the careful preservation of exist-

ing trees and the cultivation of new treeswithin an urban greenway can increase shade(thereby decreasing the needs for mechanicalcooling within adjacent buildings), createwindbreaks (decreasing heating costs duringcooler months), reduce erosion, retain/sustainshorelines and highly erosive areas, improveair quality, and intercept stormwater runoff.Urban forests have also been shown to presentlong-term benefits that are at least twice thevalue of their costs (McPherson et al., 1997).

Design considerations for urban forests:

! When choosing tree species, becareful to select trees whose waterrequirements match those of sur-rounding plants.

! Consider the maintenance needs ofthe tree species in regard to the overallgreenway design. Trees that drop fruitshould not be planted immediatelyadjacent to public access pathways, forexample.

! Avoid planting shallow rooting specieswithin three feet of paved areas toavoid tree root heaving.

! Provide sufficient soil volume tosupport the tree at maturity. Accordingto Cappiella et al. (2005), it is generallyappropriate to supply two cubic feetof usable soil for every square foot ofmature canopy.

! Consider the spatial requirements ofthe tree at maturity, and choose theplacement of each tree accordingly.See the URI Coastal Plant List formature canopy diameters of approvedtree species.

Existing trees are frequently inadvertentlykilled due to construction activities that cut,smother, or expose tree roots (Ryan et al.,2002). Soil compaction can prevent respira-


tion by the tree, while changing the soil gradearound a tree can lead to smothering or expo-sure of the tree�s roots. Applicants shouldconsult with professional arborists and land-scape architects prior to construction activi-ties to determine which trees can be preservedin the course of development. For more in-formation, see Cornell University�s Recom-mended Urban Trees (www.hort.cornell.edu/uhi/outreach/recurbtree/).

Site Assessment Checklist forUrban Tree Plantingfrom Capiella et al., 2005

· Site location and description· Climate

! USDA Hardiness Zone! Microclimate factors

· Soil factors! Range of pH levels! Texture! Compaction levels! Drainage characteristics

· Structural factors! Limitations to above-ground space

· Sunlight and irrigation levels· Other soil considerations

B. Meeting 15 percent vegetationrequirements

Some development sites may meet the 15 per-cent vegetation requirement entirely withintheir greenway. However, other sites may needto incorporate additional vegetation through-out the development to satisfy the vegetationrequirement. In the latter case, applicantsshould consider the use of green roofs, raingardens, and stormwater planters to comple-ment the greenway and any existing vegeta-tion on the site. These alternative vegetativetreatments are discussed further in Section300.

Source: M. Leighly and J. Martel, Rhode Island School of Design, 2006.

230. HYPOTHETICAL LANDSCAPING PLAN

Stormwater Management


As stormwater runoff passes overand through developed landscapes,it picks up and carries a variety of

pollutants that affect water quality (includ-ing nutrients, sediments, organic materials,toxins, and pathogens). Impervious surfacesprevent infiltration of stormwater, therebyincreasing the potential for flood damage andthe amount of pollution that enters adjoin-ing water bodies. The f low of urbanstormwater through narrow channels or pipesalso inhibits the natural hydrological cycle,concentrating and speeding up flows. Thiscan cause changes in stream morphology, in-crease flooding and erosion, and prevent in-filtration.

This section of the manual promotes a pro-cess and techniques that meet the UrbanCoastal Greenway (UCG) stormwater man-agement policy requirements, and that arealso consistent with stormwater requirementsdescribed in section 300.6 of the RhodeIsland�s Coastal Resources Management Plan,known as the �Redbook,�(www.crmc.state.ri.us/regulations/pro-grams/redbook.pdf) and the Rhode IslandStormwater Design and Installation Stan-dards Manual www.dem.ri.gov/programs/benviron/water/permits/ripdes/stwater/index.htm. The described process and tech-niques also assist the developer in comply-ing with the Narragansett Bay Commission�s(NBC) regulations that prohibit stormwaterconnections to any public sewer unless theNBC determines that a combined sewer isthe only reasonable means available for dis-posal (www.narrabay.com/Documents/PDFs/NBC%20Rules%20&%20Regs.pdf).

310 UCG STORMWATER MANAGE-MENT REQUIREMENTS

A. One hundred percent ofstormwater management shall be onsite

Stormwater management is defined in sec-tion 300.6 of the Redbook.(www.crmc.state.ri.us/regulations/pro-grams/redbook.pdf). CRMC applicants mustdemonstrate that the proposed project willmeet the stormwater management standardsset forth in the UCG policy in Section150.1(b). For purposes of the UCG require-ments, this shall be accomplished throughlow-impact development (LID) practices(e.g., swales, bioretention areas, and greenroofs) to the maximum extent practicable.

B. Stormwater treatment techniquesconstitute a hydrologically functionallandscape amenity

Where possible, stormwater treatment prac-tices should be vegetated, and designed as alandscape amenity. When site topography(or land shaping) requires hard structures aspart of the stormwater treatment design, atextured surface and use of plant materialsshould be used to soften the appearance ofthe structure and provide additional onsitevegetation.

C. Consistency with state require-ments and academic research

LID techniques have been shown to be highlyeffective in treating stormwater runoff whileimproving the hydrological functions (i.e.,reducing runoff and promoting groundwaterinfiltration) of a site. The University of NewHampshire Stormwater Center (UNHSC)

300. STORMWATER MANAGEMENT


(www.unh.edu/erg/cstev) has extensively re-searched LID practices for their effectivenessand application to the New England climate.Many of the LID practices described in thefollowing sections have been evaluated by theUNHSC. These LID methods will help ap-plicants meet the requirements under R.I.G.L.§ 45-61.2 whereby sites must maintainpredevelopment groundwater recharge, con-trol post-construction peak discharge ratesto predevelopment levels, and useLID practices as the primary method ofstormwater control. Using LID techniques isalso in agreement with the requirements ofthe NBC, which state that �no person(s) shallmake direct or indirect connections or shedstormwater from roof downspouts, founda-tion drains, areaway drains, or other sourcesof stormwater, which in turn are connectedto any public sewer unless the NBC deter-mines that a combined sewer is the only rea-sonable means available for disposal and suchconnection receives NBC approval.� (NBCRules and Regulations for Use of Wastewa-ter Facilities Within the Narragansett BayCommission District, Article 4.4).

D. Coordination with applicable agen-cies

Applicants shall coordinate their stormwatermanagement strategy with CRMC, the R.I.Department of Environmental Management(RIDEM), the municipality of jurisdiction,and the NBC, where applicable.

E. Maintenance and monitoring ofinnovative technologies

Prior to installing any experimentalstormwater treatment practice, the propertyowner must submit to CRMC, and receiveapproval on, a monitoring plan. For more in-formation, see Section 250 of the UCGPolicy, as well as CRMC�s interim policy oninnovative stormwater technologies( w w w . c r m c . r i . g o v / n e w s /2007_0207_stormwater.html).

320 MEETING UCG STORMWATERMANAGEMENT REQUIREMENTS

This section provides information on meet-ing the UCG policy standards and otherstormwater management requirements byintegrating fundamental LID site planningconcepts and techniques into the design pro-cess.

LID is an integrated approach to site devel-opment or redevelopment that focuses onreplicating predevelopment hydrologythrough the distribution and management ofstormwater across a development site. LIDaims to provide the maximum absorption andtreatment of stormwater pollutants and re-tention of stormwater prior to its loss as run-off. LID techniques capture rainwater onsite,reduce offsite runoff, infiltrate and rechargegroundwater where appropriate, remove pol-lutants (i.e. excessive nutrients, sediments,toxins, pathogens), reduce reliance upon ex-

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isting stormwater infrastructure and treat-ment facilities, and reduce infrastructure op-eration and maintenance costs.

Much of the information on LID site plan-ning is from Low Impact Development De-sign Strategies: An Integrated Design Ap-proach, prepared by the Prince George�sCounty, Maryland, Department of Environ-mental Resources (www.epa.gov/owow/nps/lid/lidnatl.pdf ), and much of the infor-mation on specific techniques is fromRIDEM�s The Urban Environmental DesignManual (www.dem.ri.gov/programs/bpoladm/suswshed/pdfs/udm3.pdf). High-lighting RIDEM-supported practices in thisCRMC manual will assist applicants in coor-dinating their stormwater management strat-egies between the two agencies.

A. LID site-planning strategies toachieve the UCG stormwater man-agement standards

Incorporating LID site-planning strategiesand techniques facilitates the developmentof site plans that are adapted to natural to-pographic constraints such as those found inurban areas, allow for full development ofthe property while maintaining the essentialsite hydrologic functions, and provide for aes-thetically pleasing, and often more effective,stormwater management controls.

It is important to consider LID approachesearly in the planning stage, as careful designcan enhance the goals and efficacy of LID.In addition, one of the attractive features ofthe LID approach is that it can incorporatesmaller, inexpensive design features as wellas larger ones. Because LID practices are dis-tributed throughout a site and are often veg-etated, it is important that landscape archi-tects and engineers collaborate early on in

the site design process.

Fundamental LID Site-PlanningConcepts

Five fundamental concepts that define theessence of LID technology must be inte-grated into the site planning process toachieve a successful and workable plan.

Concept 1 - Using Hydrology as theIntegrating Framework

Hydrology should be integrated into the siteplanning process from the beginning. Poten-tial site development and layout schemesshould be evaluated to identify potentialsources of stormwater runoff (e.g., impervi-ous surfaces such as roofs, driveways, andparking lots), and determine stormwater flowpaths. Where possible, impervious surfacesshould be reduced, minimized, and discon-nected. Further analysis should then be con-ducted on the unavoidable impervious areasto disconnect them from each other and fromexisting stormwater drainage infrastructure.Stormwater flow should be redirected so thatit is retained on site, treated and collectedfor reuse, or allowed to infiltrate where ap-propriate. Bioretention areas, infiltration de-vices, drainage swales, and many other prac-tices identified in this document can be usedto control runoff and disconnect imperviousareas. The end result is an integrated and hy-drologically functional site plan that mimicsor improves the predevelopment hydrologywhile improving aesthetic values and provid-ing recreational resources by adding landscapefeatures.

Concept 2 - Thinking Micromanagement

The key to making the LID concept work isto think small. This requires a change in per-spective or approach with respect to the size


of the area being controlled (e.g.,microsubsheds), the size of the control prac-tice (microtechniques), siting locations ofcontrols, and the size and frequency ofstorms that are controlled. Micromanagementtechniques implemented on small sub-catchments as well as on common areas al-low for a distributed control of stormwaterthroughout the entire site. This offers signifi-cant opportunities for maintaining the site�skey hydrologic functions including infiltra-tion where appropriate, depression storage,and interception, as well as a reduction inthe time of concentration. Thesemicromanagement techniques are referred toas integrated management practices. LIDpractices should be off-line controls, mean-ing that they should be designed to collectand treat runoff from small, frequent rainfallevents and bypass larger stormwater volumes.

Concept 3 - Controlling Stormwater atthe Source

The key to restoring or enhancing hydrologicfunctions is to first minimize and then miti-gate the hydrologic impacts of land-use ac-tivities close to the source of generation.Compensation or restoration of hydrologicfunctions such as interception and infiltra-tion should be implemented as close as pos-sible to the point or source where the impactor disturbance is generated. This is referredto as a distributed, at-source control strategyand is accomplished using micromanagementtechniques throughout the site.

The cost benefits of this approach can besubstantial. Typically, the most economicaland simple stormwater management strate-gies are achieved by controlling runoff at thesource. Conveyance system and control ortreatment structure costs increase with dis-tance from the source and size of the drain-age area.

The bioretention cell in this illustration demonstrates a numberof functions. First, the tree canopy provides interception andecological, hydrologic, and habitat functions. The 6-inch storagearea provides detention of runoff. The organic litter/mulchprovides pollutant removal and water storage. The planting bedsoil provides infiltration of runoff, removal of pollutants throughnumerous processes, groundwater recharge, and evapotranspi-ration through the plant material.

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Concept 4 - Using Simple, NonstructuralMethods

The use of LID techniques can offer signifi-cant advantages over conventional engi-neered facilities such as ponds or concreteconveyances. Using materials such as nativeplants, soil, and gravel makes it easier to in-tegrate these systems into the landscape, andgives them a more natural appearance thanconventionally engineered systems. The natu-ral characteristics may increase acceptanceand willingness to adopt and maintain suchsystems.

Small, distributed, microcontrol systems alsooffer a major technical advantage: one or moreof the systems can fail without underminingthe overall integrity of the site-control strat-egy.

These smaller facilities tend to feature shal-low basin depths and gentle side slopes,which also reduce safety concerns. The inte-gration of these facilities into the landscapethroughout the site offers more opportuni-

ties to mimic the site�s predevelopment hy-drologic functions and add aesthetic value.

Concept 5 - Creating a MultifunctionalLandscape and Infrastructure

LID offers an innovative alternative approachto urban stormwater management that inte-grates stormwater controls into multifunc-tional landscape features. With LID, everyurban landscape or infrastructure feature(roof, streets, parking, sidewalks, and greenspace) can be designed to be multifunctional,incorporating detention, retention, filtration,or runoff reuse.

The LID Site-Planning Process

The steps involved in integrating the LIDtechnology into the conventional site-plan-ning process are described below:

Step 1. Define Development Envelopeand Protected or Contaminated Areas

In urban areas, the development envelope islikely to be a large percentage of the total lot

This illustration shows how urbanization and increased impervious areas greatly alterthe predevelopment hydrology.



area. However, certain site features shouldbe identified early on in the site planning pro-cess. These include the location of greenwayboundaries and setbacks, public access paths,parking and other public amenities, as wellas existing vegetation that is to be preserved.In addition, areas of contamination shouldbe identified in coordination with RIDEM�sOffice of Waste Management.

Step 2. Use Minimal Disturbance Tech-niques

Minimal disturbance techniques can beused to reduce hydrologic impacts. Thesetechniques include the following:

! Reducing paving and compaction ofsoils, and restoring soils in plannedvegetated or stormwater managementareas where compaction is unavoid-able

! Minimizing the size of constructioneasements and material storage areas,and siting stockpiles within thedevelopment envelope during theconstruction phase of a project

! Siting building layout and clearing andgrading to avoid removal of existingtrees where possible

! Minimizing imperviousness by reduc-ing the total area of paved surfaces

! Disconnecting as much imperviousarea as possible to increase opportu-nities for infiltration or reuse whereappropriate and reduce runoff vol-umes

Step 3. Use Drainage/Hydrology as aDesign Element

Site hydrology evaluation and understandingare required to create a hydrologically func-tional landscape. Urbanization and increasedimpervious areas greatly alter predevelopment

hydrology (USEPA, 1993; Booth and Reinelt,1993). This increase in impervious areas hasbeen directly linked to increases in impactson receiving streams by numerous investiga-tors (including Booth and Reinelt, 1993;Horner et al., 1994; Klein, 1979; May, 1997;Steedman 1988). To reduce these impacts,LID site planning incorporates drainage/hy-drology by carefully conducting hydrologicevaluations and reviewing spatial site layoutoptions.

Hydrologic evaluation procedures can beused to minimize runoff potential and tomaintain the predevelopment time of con-centration (Tc). These procedures are incor-porated into the LID site-planning processearly on to understand and take advantageof site conditions.

Spatial organization of the site layout is alsoimportant. Unlike pipe conveyance systemsthat hide water beneath the surface and workindependently of surface topography, an opendrainage system for LID can work with natu-ral landforms and land uses to become amajor design element of a site plan. The LIDstormwater management drainage system cansuggest pathway alignment, optimum loca-tions for park and play areas, and potentialbuilding sites. The drainage system helps tointegrate urban forms, giving the develop-ment a more aesthetically pleasing relation-ship to the natural features of the site. Theintegrated site plan can also reduce develop-ment costs by minimizing earthwork and con-struction of expensive drainage structures.

Step 4. Reduce/Minimize Total ImperviousAreas

After, or concurrent with, the mapping of thedevelopment envelope, the traffic pattern androad layout and preliminary lot layout are de-



veloped. The entire traffic distribution net-work (roadways, sidewalks, driveways, andparking areas) is the greatest source of siteimperviousness. To reduce the total runoffvolume from impervious surfaces:

! Reduce road width sections to mini-mize total site imperviousness as wellas clearing and grading impacts.

! Place sidewalks on only one side ofprimary roads

! Develop greenroofs on rooftops! Use permeable materials as surfaces

for pathways and lower-traffic areas

Step 5. Develop an Integrated PreliminarySite Plan

Developing an integrated preliminary site planwill provide a base for conducting the hydro-logic analysis to compare pre- and post-de-velopment site hydrology and to confirm thatthe site will be hydrologically functional. Theprocedures described below are aimed at dis-connecting the unavoidable impervious ar-eas, as well as modifying the drainage flowpaths so that the post-development Tc ofstormwater runoff will be as similar as pos-

sible to the predevelopment conditions.

Step 6. Minimize Directly ConnectedImpervious Areas

Strategies for disconnecting the unavoid-able impervious areas include:

! Disconnecting roof drains and direct-ing flows to stabilized vegetated areasor LID practices

! Directing flows from paved areas tostabilized vegetated areas or LIDpractices

! Grading to break up flow directionsfrom large paved surfaces

! Encouraging sheet flow throughvegetated areas wherever possibleusing filter strips, level spreaders andsimilar practices

Step 7. Modify/Increase Drainage FlowPaths

The Tc, in conjunction with the hydrologicsite conditions, determines the peak dis-charge rate for a storm event. Site and infra-structure components that affect the time of

The increase in impervious areas has been directly linked toincreases in impacts on receiving streams.

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concentration include:

! Travel distance (flow path)! Slope of the ground surface and/or

water surface! Surface roughness! Channel shape, pattern, and material

components

Techniques that can affect and control theTc can be incorporated into the LID conceptby managing flow and conveyance systemswithin the development site:

a. Maximize overland sheet flow: Wherepossible, the site should be graded to maxi-mize the overland sheet flow distance throughvegetated areas along the post-developmentTc flow path. This practice will increase run-off travel times (Tt) and thus the Tc. Conse-quently, the peak discharge rate (Q) will bedecreased. Velocities in the range of two tofive feet per second are generally recom-mended. Flows can be slowed by installing alevel spreader along the upland ledge of thevegetated area or by creating a flat grassy area,or filter strip about 30 feet wide on the up-land side of the vegetated area where runoffcan spread out. This technique works beston large lots with wide greenways or largevegetated areas, and may not be viable onsmaller lots or lots where the developmentenvelope is a large percentage of the overalllot area.

b. Increase and lengthen flow paths: Increas-ing flow path of surface runoff increases in-filtration and Tt. One of the goals of a LIDsite is to provide as much overland or sheetflow as possible to increase the time it takesfor rooftop and driveway runoff to reach openswale drainage systems. To accomplish this,the designer can direct this runoff into stra-

tegically located bioretention facilities, infil-tration trenches, dry wells, or cisterns priorto its reaching the lawn. In addition, strate-gic lot grading can increase both the surfaceroughness and the travel length of the sur-face runoff.

c. Lengthen and flatten site and lot slopes:Constructing roads across steeply sloped ar-eas unnecessarily increases soil disturbanceto a site. Good road layouts avoid placingroads on steep slopes by designing roads tofollow grades and run along ridgelines. Steepsite slopes often require increased cut andfill if roads are sited using conventional lo-cal road layout regulations. If incorporatedinto the initial layout process, slope can bean asset to the development.

d. Maximize use of open swale systems:Wherever possible, LID designs should usemultifunctional open drainage systems in lieuof more conventional storm drain systems.To alleviate flooding problems and reduce theneed for conventional storm drain systems,vegetated or grassed open drainage systemsshould be provided as the primary means ofconveying surface runoff between lots andalong roadways. Lots should be graded tominimize the quantity and velocity of sur-face runoff within the open drainage systems.Infiltration controls and terraces can be usedto reduce the quantity and travel time of thesurface runoff as the need arises.

e. Increase and augment site and lot vegeta-tion: Revegetating graded areas, planting, orpreserving existing vegetation can reduce thepeak discharge rate by creating added sur-face roughness as well as provide for addi-tional retention, reducing the surface waterrunoff volume, and increasing Tt. Develop-ers and engineers should connect vegetated



buffer or greenway areas with existing veg-etation or forested areas. This technique hasthe added benefit of providing habitat corri-dors while enhancing community aesthetics.

Compare Pre- and Post-developmentHydrology

Comparing the pre- and post-developmenthydrology of the site will quantify both thelevel of control that has been provided bythe site planning process and the additionallevel of control required through the use ofintegrated management practices (IMPs).

Complete LID Site Plan

Completion of the LID site plan usually in-volves a number of iterative design steps. Thehydrologic evaluation may identify additionalstormwater control requirements for LIDtechniques distributed throughout the site.A trial-and-error iterative process is then useduntil all the stormwater management require-ments are met. In the event the site require-ments cannot be met with LID techniquesalone, additional stormwater controls can beprovided using conventional stormwatertechniques. Mixed use of LID measures andconventional control is referred to as a hy-brid system.



Hydrologic functions of LID techniques

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Once the predevelopment hydrology objec-tives have been met, the designer can com-plete the site plan by incorporating the typi-cal details, plan views, cross sections, pro-files, and notes as required.

B. Procedures for Selection and De-sign of LID Techniques

The following steps guide the designerthrough the selection and design process.Again, because of the �multifunctional� na-ture of an LID project, it is essential that li-censed professionals from both the landscapearchitecture and engineering fields collabo-rate early on in the planning and design pro-cess.

Step 1: Define Hydrologic ControlsRequired

Hydrologic functions such as infiltration, fre-quency and volume of discharges, andgroundwater recharge become essential con-siderations when identifying and selectingLID techniques. The hydrologic functions canbe quantified with respect to the various de-sign parameters, which include runoff vol-ume, peak discharge, frequency and durationof discharge, groundwater recharge, and wa-ter quality parameters. When these design pa-rameters are quantified for predevelopmentconditions, they define or quantify the hy-drologic controls required for a specific site.



Step 2: Evaluate Site Opportunities andConstraints

The LID concept encourages innovation andcreativity in the management of site impacts.The site should be evaluated for physical con-ditions such as available space, infiltrationcharacteristics, possible soil contamination,and slopes.

Step 3: Screen for Candidate Practices

Management practices that are feasible andappropriate for the site should be chosen.Screening should consider both the site con-straints and the hydrologic and water qualityfunctions.

It is important to recognize that LIDstormwater management is not simply a mat-ter of selecting from a menu of available pre-ferred practices. Rather, it is an integratedplanning and design process. The preferredpractices by themselves might not be suffi-cient to restore the hydrologic functions of asite without the accompanying site planningprocedures described above.

Step 4: Evaluate Candidate LIDs inVarious Configurations

After the candidate LID practices are identi-fied, they are deployed as appropriatethroughout the site and the hydrologic meth-ods are applied to determine whether the mixof LID practices meets the hydrologic con-trol objectives identified in Step 1. Typically,on the first design attempt the hydrologiccontrol objectives are not met precisely butinstead are overestimated or underestimated.An iterative process might be necessary, ad-justing the number and size of LIDs until thehydrologic control objectives are optimized.

Step 5: Select Preferred Configurationand Design

The iterative design process typically identi-fies a number of potential configurations andmixes of LID practices such as bioretentionstructures, water storage and reuse systems,dry wells, infiltration trenches, vegetatedswales, and other practices to provide therequired level of hydrologic control at a rea-sonable cost. When configuring multiple LIDpractices, keep in mind that placing controlsin series provides for maximum on-lotstormwater runoff control (i.e., the maxi-mum mitigation of site development impactson the natural hydrology). This type of de-sign control is known as a hybrid and is ef-fective in reducing both volume and peakflow rate.

Step 6: Design Conventional Controls ifNecessary

If for any reason the hydrologic control re-quirements for a given site cannot beachieved using LID practices it might be nec-essary to add conventional controls to meetstormwater management requirements, par-ticularly peak discharge control. Site con-straints such as low-permeability soils, con-tamination, high water table, shallow bed-rock, or space limitations can preclude theuse of some LID practices. In these situa-tions it is recommended that LIDs be usedto the extent possible and then supplementedwith conventional controls to meet the re-maining hydrologic design objectives. Keepin mind that LID practices should be kept�off-line,� and be designed to handle smaller,frequent rainfall events, while bypassinglarger volumes. If peak control for largerstorm events is required, conventional con-trols may also have to be used.


Suitability Criteria/ Factors for LID IMPs

The site designer should consider or evaluate the following factors when selectingLID IMPs.

Space/Real Estate Requirements. The amount of space required for stormwatermanagement controls is always a consideration in the selection of the appropriatecontrol. LID IMPSs, because they are integrated into and distributed throughoutthe site�s landscape, typically do not require that a separate area be set aside anddedicated to stormwater management

Soils. Soils and subsoil conditions are very important consideration in every facetof LID technology, including the site planning process, the hydrologic consider-ations, and the selection of appropriate IMPs. The use of micromanagement prac-tices, as well as the use of underdrains to provide positive subdrainage forbioretention practices, helps to overcome many of the traditional soil limitations forthe selection and use of IMPs.

Slopes. Slope can be a limiting factor when the use of the larger traditional stormwatercontrols is considered. With the application of the distribution micromanagmentIMPs however, slope is seldom a limiting factor; it simply becomes a design elementthat is incorporated into the hydrologically functional landscape plan.

Water Table. The presence of a high water table calls for special precautions inevery aspect of site planning and stormwater management. The general criterion isto provide at least 2 to 4 feet of separation between the bottom of the IMP andthe top of the seasonally high water table elevation. Also, the potential for con-tamination should be considered especially when urban landscape hotspots areinvolved.

Proximity to Foundations. Care must be taken not to locate infiltration IMPs tooclose to foundations of buildings and other structures. Considerations include dis-tance, depth, and slope.

Maximum Depth. By their nature, the micromanagement practices that make upthe LID IMPs do not require much depth, and thus this factor is no usually a majorconcern. Bioretention cells, for example, usually allow only 6 inches of pondingdepth, and 2 to 4 feet of depth for the planting soil zones.

Maintenance Burden. Maintenance costs for traditional stormwater controls aresignificant and have become a considerable burden for local governments andcommunities. Maintenance costs can equal or exceed the initial construction cost.In comparison, many of the IMPs require little more than normal landscaping main-tenance treatment. Additionally, this cost is typically the responsibility of theindividual property owner rather than the general public. Communities are advisedto retain the authority to maintain their sites if they fail to function as designed.

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C. LID Techniques

LID techniques are designed for on-lot use.This approach reduces or eliminates the needfor large centralized parcels of land to con-trol end-of-pipe runoff. LID techniques andsite design strategies should be developed toprovide quantity and quality control, includ-ing groundwater recharge through infiltrationof runoff into the soil, retention or deten-tion of runoff for permanent storage or forlater release, and pollutant settling and en-trapment by conveying runoff slowly throughvegetated swales and buffer strips. In addi-tion, LID can provide an added aestheticvalue to the property since many LID prac-tices are vegetated and may double as land-scape amenities.

Examples of specific LID techniques aredescribed below. They include:

! Bioretention filter! Green rooftop systems! Water storage and reuse systems! Stormwater planters! Tree box filters! Permeable paving! Open channels

Bioretention filter

Introduction

The bioretention filter (also referred to as a�rain garden� or a �biofilter�) is a stormwatermanagement practice to manage and treatstormwater runoff using a conditioned soilbed and planting materials to filter runoffstored within a shallow depression. Themethod combines physical filtering and ad-sorption with bio-geochemical processes toremove pollutants. The system consists ofan inflow component, a pretreatment ele-

ment, an overflow structure, a shallowponding area (less than nine inches deep), asurface organic layer of mulch, a planting soilbed, plant materials, and may also include anunderdrain system. Biortention facilities canbe designed as �exfilter� systems, where therunoff that enters the system is allowed topercolate through the bioretention soil me-dia and into the underlying soils, allowing forgroundwater recharge. In situations wherethis is not advisable, such as on sites wherethe underlying soils may be contaminated,bioretention facilities can be lined to preventinfiltration of runoff to groundwater. In thesesystems, the runoff passes through thebioretention soil media and is conveyed viaan underdrain system to the existingstormwater drainage system or other down-stream facility.

Facility Application

The bioretention facility is one of the moreversatile structural stormwater managementmeasures. The practice can be applied tomanage almost every land-use type from verydense urban areas to more rural residentialapplications. It is ideally adapted forultraurban redevelopment projects. Thebioretention system is intended to captureand manage relatively small volumes of wa-ter from relatively small drainage areas (gen-erally less than five acres). Consequently, thesystem is rarely utilized on the watershedscale to manage large drainage areas. The sys-tem also is rarely used to manage large stormsor to provide peak flow attenuation for theso-called �channel forming� storms (i.e, inthe range of the one-year to 1.5-year fre-quency return interval) or flood controlevents (i.e., 10-year to 100-year frequencyreturn intervals). As a general rule, it�s rec-ommended that bioretention areas be de-


signed as off-line practices that capture onlythe water quality volume from a drainagearea, and bypass larger storm runoff volumesthrough the use of a flow diversion structureor similar method.

Benefits

Bioretention can have many benefits whenapplied to redevelopment and infill projectsin urban centers. The most notable include:

! Effective pollutant treatment forsolids, metals, nutrients, and hydro-carbons

! Groundwater recharge augmentation(if designed as an exfilter, wheresoils, land uses, and groundwaterelevations permit)

! Micro-scale habitat and reduction of

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urban �heat island� effects! Aesthetic improvement to otherwise

hard urban surfaces! Ease of maintenance, coupling

routine landscaping maintenance witheffective stormwater managementcontrol



! Safety. The bioretention system is avery shallow depression that poseslittle risk to vehicles, children or thegeneral public

Limitations

Bioretention facilities have some limitationsthat restrict their application. The most no-table of these include:

! Steep slopes. Bioretention requiresrelatively flat slopes to be able toaccommodate runoff filtering throughthe system.

! Direct entry of runoff at the surfaceof the facility. The bioretentionsystem is designed to receive runofffrom sheet flow from an imperviousarea or by entry by a roof draindownspout. Because the systemworks by filtration through a condi-tioned planting media, runoff mustenter at the surface. If drainage ispiped to the treatment area, runoffmay enter the facility several feetbelow grade, thus requiring significantexcavation.

! Minimum head requirements. Becausethe system is designed to filter runoffthrough the soil media, a minimum

head is required. The bioretention soilmust have an infiltration rate of 0.5to 2.0 ft/day. Underlying soils shouldbelong to hydrologic soil group(HSG) A. Some HSG B soils areappropriate.

! Bioretention facilities alone rarelymeet all stormwater managementobjectives. If channel protection and/or flood controls are necessary for agiven project, another practice isgenerally required.

! Bioretention requires a modest landarea to effectively capture and treatrunoff from storms up to approxi-mately the 1-inch precipitation event(i.e., approximately 5 percent of theimpervious area draining to thefacility).

! Contamination of underlying soils. Inareas where there are contaminatedsoils, such as brownfield sites,bioretention facilities should not bedesigned as exfilter system, butshould be lined to prevent potentialcontamination of groundwater.

Sizing and Design Guidance

Bioretention facility surface areas are typi-cally sized at a ratio of 5 percent of the im-

This profile of bioretention illustrates planting zones.

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pervious area draining to the facility to cap-ture, manage, and treat runoff from the one-inch precipitation event (Claytor & Schueler,1996). The basis for this guideline relies onthe principles of Darcy�s Law, where liquidis passed through porous media with a givenhead, a given hydraulic conductivity, over agiven timeframe. The basic equation for siz-ing the required bioretention facility surfacearea is as follows:

Af = Vol*(df) / [k*(hf +df)(tf)]where:

Af = the required surface area of thebioretention facility (ft2)Vol = the treatment volume (ft3)df = depth of the bioretention system (ft,usually set at 4 ft)k = the hydraulic conductivity (in ft/day, usu-ally set at 0.5 ft/day, but can be varied de-pending on the properties of the soil media,up to a maximum of 2 ft/day)hf = average height of water above thebioretention bed (usually set at 3 inches

tf = the design time to filter the treatmentvolume through the filter media (usually setat 72 hours)

The 5 percent guideline can be modified bychanging one or more of the above designvariables. For instance, if a designer has ahigh water table, the depth might be reducedfrom the typical four feet to as low as 18inches, or the media composition might bealtered to allow for a higher hydraulic con-ductivity. In addition, there are several physi-cal geometry recommendations that shouldbe considered in the layout and design ofbioretention facilities. The following designguidance is suggested:

! Minimum width: 10 feet

! Minimum length: 15 feet! Length to width ratio: 2:1! Maximum ponding depth: nine inches! Planting soil depth: four feet, consist-

ing of 50 percent sand, 20 percentleaf mulch, and 30 percent topsoilconsisting of less than 10 percentclay content, and an organic or mulchlayer (three inch maximum) or aherbaceous plant layer (70 percent to80 percent coverage)

! Underdrain system: six-inch pipe ineight-inch gravel bed

! The minimum width allows forrandom spacing of trees and shrubsand also allows for the plantingdensities specified above, which helpcreate a micro-environment wherestresses from urban stormwaterpollutants, drought, and exposure arelessened. For widths greater than 10feet, a minimum length to width ratioalong the stormwater flowpath of 2:1is recommended. This longerflowpath allows for the settlement ofparticulates and maximizes the edgeto interior ratio. The recommendedmaximum ponding depth of nineinches provides surface storage ofstormwater runoff, but is not toodeep to affect plant health, safety, orcreate an environment of stagnantconditions. The ponded water willalso dissipate in less than 72 hours(and in most cases within a fewhours), which maintains the flexibilityin plant species selection. Thebioretention system relies on asuccessful plant community to createthe microenvironmental conditionsnecessary to replicate the functionsof a forested ecosystem. To do that,plant species need to be selected thatare adaptable to the wet/dry condi-



tions that will be present. A mix ofupland and wetland trees, shrubs, andherbaceous plant materials are recom-mended that are arranged in a randomand natural configuration startingfrom the more upland species at theouter most zone of the system tomore wetland species at the innermost zone.

Cost

Bioretention facilities are cost-effective mea-sures designed to help meet many of themanagement objectives of watershed protec-tion. Because these facilities are typicallysized as a percentage of the impervious area,the cost is relatively constant with drainagearea. Unlike retention ponds and constructedstormwater wetlands, whose cost decreaseswith increasing drainage area, bioretentiondoes not benefit from economies of scale.Typical capital construction costs are in therange of approximately $5 to $6 per cubicfoot of storage. Another method of estimat-ing cost is based on the impervious covertreated. Bioretention facilities range from ap-proximately $18,000 to $20,000 per imper-vious acre (CWP, 1998). Annual maintenance

cost is approximately 5 percent to 7 percentof capital construction costs or in the rangeof $900 to $1,000 per impervious acretreated.

Maintenance

Inspections are an integral part of systemmaintenance. During the first six months af-ter construction, bioretention facilities shouldbe inspected at least twice following precipi-tation events of at least 0.5 inch to ensurethat the system is functioning properly. There-after, inspections should be conducted on anannual basis and after storm events of greaterthan or equal to the one-year precipitationevent (approximately 2.6 inches in RhodeIsland). Minor soil erosion gullies should berepaired when they occur. Pruning or replace-ment of woody vegetation should occurwhen dead or dying vegetation is observed.Division of herbaceous plants should occurwhen over-crowding is observed, or approxi-mately once every three years. The mulchlayer should also be replenished (to the origi-nal design depth) every other year as directedby inspection reports. The previous mulchlayer would be removed, and properly dis-

Center for Watershed Protection, 2002


posed of, or roto-tilled into the soil surface.If at least 50 percent vegetation coverage isnot established after two years, a reinforce-ment planting should be performed. If thesurface of the bioretention system becomesclogged to the point that standing water isobserved on the surface 48 hours after pre-cipitation events, the surface should be roto-tilled or cultivated to breakup any hard-packed sediment and then revegetated.

Green rooftop systems

Introduction

A green roof is created by adding a layer ofgrowing medium and plants on top of a tra-ditional roof system. Green roofs are becom-ing more commonly used for stormwatermanagement, and are suitable for urban ret-rofits as well as for new buildings. A greenroof is different from a roof garden. A roofgarden consists of freestanding containersand planters on a terrace or deck. Green roofsconsist of the following components, start-ing from the top down:

! Plants, often specially selected forparticular application

! Engineered growing medium! Landscape or filter cloth to contain

the roots and the growing medium,while allowing for water to filtratebelow the surface into the medium

! Drainage layer! Waterproofing/roof membrane, with

an integral root repellent! Roof structure, with traditional

insulation. Excess precipitation(beyond what is absorbed by themedium) filters through the growingmedium and is collected in thedrainage layer.

The drainage layer may contain a built-in wa-ter reservoir. The remaining stormwater isthen drained into a conventional downspout.During large storm events there is an over-flow drain to minimize ponding on the roof-top.


There are two different types of green roofs:extensive and intensive. Extensive greenroofs are often not accessible and are gener-ally characterized by low weight, low capitalcost, low plant diversity, and minimal main-tenance requirements. Intensive green roofsoften have pedestrian access and are charac-terized by deeper soil and greater weight,higher capital cost, increased plant diversity,and more maintenance requirements.

Extensive roofs typically have a mineral basemixture of sand, gravel, crushed brick, leca,peat, organic matter and some soil as thegrowing medium. These are generally lighterthan saturated soil. The growing mediumdepth ranges from two to six inches with aweight increase from a range of 16 to 36 lbs/sf when fully saturated. Due to the shallow-ness of the growing medium and the extremedesertlike condition on many roofs, the se-lected plants will need to be low and hardy.The figure above illustrates a cross sectionof a proprietary extensive roof. Intensiverooftops often have a soil-based growing me-dium, ranging from eight to 24 inches. Thisincreases the loading weight from the satu-rated soil from a range of 60 to 200 poundsper square foot (lbs/sf) (Peck and Kuhn).With an intensive roof, plant selection ismore diverse and can include trees and shrubsdue to the deeper growing medium. This al-lows for the development of a more com-plex ecosystem but with this diversity a higherlevel of maintenance is required.



Benefits

Green roofs provide many benefits both pri-vately and publicly. Direct benefits to privateowners may include:

! Energy Savings - Green roofs provideinsulation from the heat and the cold,reducing the amount of energyrequired to heat or cool the building.

! Extend Life of Roof - Green roofsprotect roofing membranes fromextreme temperature fluctuations andfrom the negative impacts of ultra-violet radiation.

! Sound Insulation - Green roofs can bedesigned to insulate against outsidenoises.

! Fire Resistance - When fully satu-rated, green roofs can help stop thespread of fire to and from buildingrooftops. The two major public

benefits from green roofs are areduction in urban heat island effectsand stormwater retention capability.Urban heat island is the overheatingof urban and suburban areas, due toincreased paved, built-over, and hardsurface areas. The urban heat islandeffect increases electricity and airconditioning costs. Green roof topsintercept and absorb solar radiation.

Green roofs can be designed as effectivestormwater management controls. The grow-ing medium on both intensive and extensivegreen roofs can act as a stormwater pretreat-ment system. The method combines physi-cal filtering and adsorption with biogeochemi-cal processes to remove pollutants. Greenroofs can be designed for stormwater reten-tion capability, therefore reducing the over-all stormwater runoff volume from rooftops.Stormwater retention rates are determined

Schematic cross section of an extensive green roof

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by saturated filtration capacity, thickness ofthe growing medium, field capacity, poros-ity, under-drainage layer, water retention,flow, and relief drain spacing. A heavily veg-etated green roof with eight to 16 inches ofgrowing medium can hold four to six inchesof water (Peck and Kuhn).

Limitations

Green roofs are best suited for new build-ings, where structural considerations can beincorporated early in the design phase. Ret-rofits to existing buildings are possible. Thelimiting factor when dealing with retrofittingis soil weight. Soil weighs approximately 100lbs/sf, while existing roofs are typically de-signed for a live load of 40 lbs/sf, which in-cludes snow load. Since an extensive systemcan weigh 16 to 36 lbs/sf and an intensivesystem can weigh 60 to 200 lbs/sf, fully satu-rated, an existing roof may need consider-able reinforcement before it can support theweight of a green roof. A landscape archi-tect or horticulturist can advise on certainplants that do not require a deep soil layer,thereby reducing the weight on the roof.Other limiting factors are the initial costs andmaintenance costs of a green rooftop. Instal-lation costs for green rooftops are consider-ably higher (25 percent to 300 percent) thanfor conventional roofs. Maintenance costs canrange from $1.25 to $2.00 per square footannually, depending on the system.

Green roofs may not be suitable to heavy in-dustrial areas. These areas are prone to highlevels of dust and/or chemicals in the air thatmay cause damage to plants. Green roofs arealso limited in their stormwater quantity con-trol capability. Green roofs do not provideflood control or channel protection for anystorm greater than one inch and do not pro-

vide recharge to groundwater unless a sepa-rate infiltration system is designed on site.

Sizing and Design Considerations

To design and implement green rooftops, thefollowing issues need to be considered:

Schematic cross section of an intensivegreen roof

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! Condition of the existing roof isimportant. The most cost effectivetime to construct a green roof iswhen a roof needs to be replaced ornewly constructed. A waterproofmembrane and root resistance layerwill need to be placed on all rooftops.

! Structural capacity of the roof willdictate the type of green roof thatcan be built.

! Access to the roof is an importantconsideration. Depending on the typeof green roof, safe public access maybe required. In addition, access totransport materials for constructionand maintenance will be required.

! The weight of the green roof mustnot exceed the structural capacity ofthe roof.

! In addition to the cost for construc-tion, materials, and permits, the costsfor hiring specialists, such as struc-tural engineers or horticulturists, aswell as for making any needed struc-tural and safety improvements,should be taken into consideration.

Components of a green roof can be boughtand installed separately, or proprietary assem-bly can be purchased. In either case, the ba-sic components starting from the roof up arethe following:

! Insulation layer, a waterproof mem-brane to protect the building fromleaks, and a root barrier to preventroots from penetrating the waterproofmembrane.

! Drainage layer, usually made oflightweight gravel, clay, or plastic.The drainage layer keeps the growingmedia aerated and can be designed toretain water for plant uptake at a latertime.

! Geotextile or filter fabric that allowswater to soak through but preventserosion of fine soil particles.

! Growing media that helps withdrainage while providing nutrients forplant uptake.

! Plants, typically for extensive greenroofs, a mixture of grasses, mosses,sedums, sempervivums, festucas,irises, and wildflowers that are nativeto drylands, tundras, alvars, andalpine slopes. For intensive greenroofs, with few exceptions, thechoices are limitless. See Table 2 foran example of plant species used inthe Chicago city hall green rooftop.

! A wind blanket, used to keep thegrowing media in place until the rootsof the plant take hold.

Cost

All green roofs share common components;however there are no standard costs forimplementation. In the United States, thecost range for extensive roof systems rangesfrom $15 to $20 per square foot (Scholz-Barth, 2001).

Maintenance

Maintenance of a green roof system requiresplant maintenance as well as maintenance tothe waterproof membrane. Depending onwhether the green roof is an extensive or in-tensive system, the plant maintenance willrange from two to three yearly inspections tocheck for weeds or damage, to weekly visitsfor irrigation, pruning and replanting.

Regular maintenance inspections should bescheduled, as for a standard roof inspection.Any leaks in the roof should be checked outimmediately. Green roofs protects the water-


proof membrane from puncture damage andsolar radiation, however, leaks can occur atjoints, penetrations and flashings, due moreto installation than material failure. Drainsshould also be inspected for possible breachin filter cloth and cleaned on a regular basis.

Water storage and reuse systems

Rain barrels and cisterns are automatic wa-ter collection systems that store runoff fromstormwater to be used later for activities suchas lawn and garden watering or temporarystorage of runoff for infiltration of stormrunoff through a passive system into an �en-gineered� soil. Reuse of stormwater runoffis beneficial to the environment because thestored water would otherwise enter the stormsewer, increasing the volume of dischargeinto receiving waters. In older cities, such asmany in Rhode Island with combined sewersystems, the addition of stormwater also con-tributes to sanitary sewer overflows. Rain bar-rels are small barrels (50 to 250 gallons)placed on the end of a downspout that storerunoff for future irrigation use. A cistern issimilar to a rain barrel, but it has muchgreater storage capacity and can be designedto collect and store runoff for watering lawnsand gardens and/or for infiltration into theground. The basic components of any rainbarrel are relatively simple. Rain barrels con-sist of an actual barrel, often made of plas-tic, a sealed yet removable child- and ani-mal-resistant top, connections to the down-spout, a runoff pipe and a spigot. A numberof accessories can be added, such as addi-tional barrels for expanded storage volume,a water diversion soaker hose, an automaticoverflow, or an automatic irrigation overflowand/or an infiltration system. Cisterns canbe constructed of any impervious, water-re-taining material. They can be located eitherabove or below ground and can be con-

structed on-site or pre-manufactured and thenplaced on-site. The basic components of acistern include a secure cover, a leaf/mos-quito screen, a coarse inlet filter with clean-out valve, an overflow pipe, a manhole, asump, a drain for cleaning, and an extractionsystem (tap or pump). Additional featuresmight include a water-level indicator, a sedi-ment trap, or an additional tank for more stor-age volume.


Rain barrels and cisterns can be used in mostareas (residential, commercial, and industrial)due to their minimal site constraints relativeto other stormwater management practices.The sizes of barrels or cisterns are directlyproportional to their contributing drainage ar-eas.

Benefits

Rain barrels and cisterns are low-cost waterconservation devices that can reduce runoffvolume from smaller storm events, and de-lay and reducepeak runoffflow rates. Bystoring and di-verting runofffrom impervi-ous areas suchas roofs, thesedevices reducethe undesirableimpacts of run-off that wouldotherwise flowswiftly into re-ceiving watersand contributeto flooding anderosion. Stored Cisterns

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water from rain barrels and cisterns can helpreduce water consumption, thereby reducingwater costs. Water reuse ultimately reducesthe demand on municipal water systems andsupplies, as well as reducing the amount ofstormwater entering combined sewer systems(CSOs).

Limitations

Rain barrels and cisterns are physically lim-ited by their size. Once the rain barrels orcisterns are full, additional stormwater willoverflow onto surrounding areas and/or intothe downstream drainage system. Rain bar-rels and cisterns are storage practices. Theyallow for reuse of stored rainwater, but donot allow for infiltration of stormwater run-off and groundwater recharge.


The sizing for rain barrels and cisterns is afunction of the impervious area that drainsto the device. The basic equation for sizing arain barrel or a cistern is as follows:

Vol = A * R * 0.90 * 7.5 gals/ft3where:

Vol = Volume of rain barrel or cistern (gal-lons)A = Impervious surface area draining intobarrel or cistern (ft2)R = Rainfall (feet)0.90 = Loss to system (unitless)7.5 = Conversion factor (gallons per cubicfoot

A cistern can be located beneath a singledownspout or one large cistern can be locatedto collect stormwater from several sources.Due to the size of rooftops and the amountof contributing impervious area, increased

runoff volume and peak discharge rates forcommercial and industrial sites may requirelarge capacity cisterns. Cisterns can be locatedabove or below ground, and can be con-structed on site or pre-manufactured and thenplaced on site. Cistern sizes can vary fromhundreds of gallons for residential uses totens of thousands of gallons for commercialand/or industrial uses.

Cost

Rain barrels are relatively low cost, pre-manufactured systems averaging about $120,minus downspout and other accessories(UGRC). Basic supplies to construct a barrelcan be as low as $20. The cost for a cisterncan vary greatly depending on its size, mate-rial, and location (above or below ground).

Maintenance

Maintenance requirements for rain barrels andcisterns are minimal and consist of biannualinspections of the unit.

The average cost for a typical manually con-structed cistern for residential use made ofreinforced concrete (3,000 gallons), minus la-bor, would be approximately $1,000

Cistern

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(Kessner, 2000).

Stormwater planters and tree boxfilters

Stormwater planters are small-scalestormwater treatment systems comprised oforganic soil media and plants in a confinedplanter box. Stormwater planters are simply�bioretention in-a-box.� Planters generallylook like large vaulted plant boxes and cancontain anything from basic wildflower com-

munities to complex arrangements of treesand flowering shrubs. The method combinesphysical filtering and adsorption with bio-geochemical processes to remove pollutants.There are three basic variations of thestormwater planters: the contained system,the infiltration system, and the flow-throughsystem. Contained planters are typically largeself-contained planters found on terraces,deck and sidewalks. Infiltration planter boxesare designed to allow runoff to filter throughthe planter soils and then infiltrate into the

Source: Urban Environmental Design Manual

Rain barrel and cistern maintenance Source: Urban Environmental Design Manual



native soils. Flow-through planter boxes aredesigned with impervious bottoms or placedon impervious surfaces. This flow-throughsystem consists of an inflow component (usu-ally a downspout), a treatment element (soilmedium), an overflow structure, plant mate-rials, and an underdrain collection system todivert treated runoff back into the down-stream drainage system.

Tree planters or tree box filters are a specifictype of stormwater planter. They are essen-tially the same type of self-contained deviceas a stormwater planter, but have the depthand size allowable for trees as opposed tosmaller shrubs. Tree planters may also be lo-cated in areas similar to those used bystormwater planters, as long as thestormwater runoff is properly directed to theplanter. The types of trees used must be ableto survive in urban environments, in dry pe-riods, and during periodic inundations of pre-cipitation. A tree box filter, with its enclosednon-permeable concrete container, is idealfor situations where infiltration is undesirableor not possible. These situations include claysoils, karst topography, high groundwaterconditions, and close proximity to buildings,steep slopes, contaminated soils, brownfieldssites, highly contaminated runoff, mainte-nance facilities, and gas stations. For hot spotswhere chemical spills are likely, the under-drain system can be fitted with an emergencyshut-off valve to quickly close the dischargedrain pipe, isolating the spill in the concretecontainer for easy clean-up, removal, and re-placement of the filter system.

Tree box filters are unique, since a major de-cision is to consider how to integrate theirplants into landscape designs. They can beblended into the landscape scheme or theycan be the centerpiece of the landscape de-sign.

Tree planting pits in sidewalks are anotheroption to integrate trees into an urban set-ting. Trees are planted individually, or soil isplaced in a continuous channel under thepavement to connect several pits and allowfor greater volumes of soil for root growthand water storage. If the pits are plantedabove the surface, supplemental fertilizationand irrigation may be required. Pits locatedat surface level may require ground coveraround the base of the tree to minimize foottraffic over the tree roots. A cover or gratearound the base of the tree that allows fortree growth will be required if the pit soillevel is two to eight inches below the pave-ment surface.


Stormwater planters are ideally adapted for

Infiltration planter

Source: City of Portland Stormwater Management Manual

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ultra-urban redevelopment projects. Roofrunoff can be directed from the downspoutdirectly into the planters. Runoff from roof-top areas contains nutrients carried in rain-water, sediments and dust from rooftops, andbacteria from bird droppings. These pollut-ants can all be attenuated to a significantdegree during small rain events. Planters canbe effective in reducing the velocity and vol-ume of stormwater discharge from rooftopareas. Another benefit of stormwater plant-ers is the relatively low cost. These are smallself-contained units that can be easily con-structed without heavy-duty excavation thataccompanies other practices. Stormwaterplanters also add aesthetic elements by im-proving the surrounding streetscape. Thesesystems are rarely used to manage large

storms. Any storm greater than the infiltra-tion capacity of the soil will flood the plant-ers and will overflow onto the street or intoan overflow pipe. Planters should be designedto attenuate water no more than three to fourhours after an average storm. The topsoil (soilmedium) should have an infiltration rate oftwo inches per hour. The drainage layer (sandor gravel) should have a minimum infiltra-tion rate of five inches per hour. Infiltrationplanters are also known as �exfilters.� Anexfilter is a system designed to filter runoffthrough the soil media before infiltration intothe underlying soil. If poor soils or highgroundwater would prevent conventional in-filtration, then a contained or a flow-throughstormwater planter is recommended.

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Benefits

Stormwater planters can have many benefitswhen applied to redevelopment and infillprojects in urban centers. The most notablebenefits include:

! Effective pollutant treatment forsolids, metals, nutrients, and hydro-carbons

! Groundwater recharge augmentation(if designed as an exfilter, wheresoils, land uses, and groundwaterelevations permit)

! Micro-scale habitat! Aesthetic improvement to otherwise

hard urban surfaces! Ease of maintenance, coupling

routine landscaping maintenance witheffective stormwater managementcontrol

! Low cost relative to other practices

Limitations

Stormwater planters are limited in the amountof runoff they can receive. Infiltration andflow-through planter boxes should receivedrainage from no more than 15,000 square

feet of impervious area. Any storm eventgreater than two inches per hour (topsoil in-filtration rate) will start to pond in the plant-ers and eventually overflow onto the streetor into the underdrain system and thereforewill not be treated for water quality.

Frequently soils under pavement are com-pacted to meet load-bearing requirements andengineering standards. This reduces thechances for a healthy root system to grow,which results in the premature death of thetree. Use of a new pavement substrate called�structural soil� can be compacted to meetengineering requirements as well as to allowtrees to develop a productive root system.


The basis for this guideline relies on the prin-ciples of Darcy�s Law, where liquid is passedthrough porous media with a given head, agiven hydraulic conductivity, over a giventimeframe. The basic equation for sizingstormwater planters is as follows:

Af = Vol*(df) / [k*(hf +df)(tf)]where:

Flow-through planter

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Af = the required surface area (ft2)Vol = the treatment volume (ft3)D f = depth of the soil medium (ft)k = the hydraulic conductivity (in ft/day, usu-ally set at 4 ft/day, but can be varied depend-ing on the properties of the soil media)hf = average height of water above theplanter bed (maximum 12 inches)tf = the design time to filter the treatmentvolume through the filter media (usually setat three to four hours)

In addition, there areseveral physical geom-etry recommendationsthat should be consid-ered in the layout anddesign of stormwaterplanters. The followingdesign guidance is sug-gested:

! Minimum width:1.5 feet (flow throughplanters) 2.5 feet(infiltration planters)

! Minimum length: none! Maximum ponding depth: 12 inches! Minimum building offset: 10 feet

(applies to infiltration planters only)

Stormwater planters rely on successful plantcommunities to create the micro-environ-mental conditions necessary to replicate thefunctions of a forested ecosystem. To do that,plant species need to be selected that areadaptable to the wet/dry conditions that willbe present.

CRMC encourages the development ofunique and innovative designs for stormwaterplanters in urban areas, including designs thatroute stormwater runoff from outside intothe building, and use it to water indoor plant-

ers that help to visually enhance commonareas such as building lobbies.

Cost

Stormwater planters are cost-effective mea-sures designed to help meet many of themanagement objectives of watershed protec-tion. Since stormwater planters are intendedonly for roof runoff, they are much more costeffective than other roof treatment systems,such as green roofs. Although stormwaterplanters often function with the same pro-cesses as bioretention systems and rain gar-dens, they may be more cost effective in ul-tra-urban areas due to the ability to retrofitthe planters directly adjacent to buildings oralongside sidewalks where space is limited.Planters may also have lower costs per areafor smaller treatment areas as opposed to site-specific designs of other practices.

An example cost estimate for a proprietaryflow-through system is approximately$24,000 per acre of impervious surface. An-nual maintenance cost is approximately 2 per-cent to 8 percent of the system cost, or inthe range of $200 to $2,000 per imperviousacre treated.

Maintenance

Inspections are an integral part of systemmaintenance. During the six months imme-diately after construction, and following pre-cipitation events of at least 0.5 inches, plant-ers should be inspected at least twice to en-sure that the system is functioning properly.Thereafter, inspections should be conductedon an annual basis and after storm events ofgreater than or equal to the one-year precipi-tation event (approximately 2.6 inches inRhode Island). Minor soil erosion gulliesshould be repaired when they occur. Pruning



or replacement of woody vegetation shouldoccur when dead or dying vegetation is ob-served. Herbaceous perennials should be di-vided when over-crowding is observed, orapproximately once every three years.

Permeable paving and porous asphalt

Permeable paving is a broadly defined groupof pervious types of pavements used forroads, parking, sidewalks, and plaza surfaces.Most of these consist of a permeable sur-face layer with enough structural integrity tosupport at least light vehicular use, andsubgrade layer or layers of materials such asaggregate that provide a structural base andallow for storage and infiltration ofstormwater. Permeable paving reduces im-pacts of impervious cover by allowing run-off to infiltrate, augmenting the recharge ofgroundwater, and enhancing pollutant uptakeremoval in the underlying soils. Permeablepavement can even result in reduced main-tenance requirements by improving the drain-age characteristics of an impervious area.There are many different types of permeablepaving, including:

! Concrete grid pavers! Lattice-style paving that includes

grass in spaces in between latticework

! Porous pavement that looks likeregular pavement (asphalt or con-crete) but is manufactured withoutfine (small particle-size) materials

! Cobblestone! Brick! Plastic modular blocks! Crushed aggregate or gravel

Porous asphalt is similar to traditional asphalt,but is manufactured without fine materialsto increase its porosity and allow water topass through it. It is typically constructedover an aggregate base which allows runoffto infiltrate through it into the underlyingsoils. Its application in parking lots has beenstudied at the University of New Hampshire,where it has been shown to be a very effec-tive stormwater management practice. Forthe results of these studies, as well as porousasphalt manufacturing and design specifica-tions developed by UNH, see the UNHStormwater Center�s website atwww.unh.edu/erg/cstev/ or on the CRMCwebsite at www.crmc.ri.gov/samp/sampfiles/UNHSC_PA_Spec_July_07.pdf.

Typical cross-section of a pervious pavingsystem

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The ideal application for permeable pavingis on low traffic roads, overflow parking ar-eas, sidewalks, plazas, and courtyard areas.Permeable paving is intended to capture andmanage small frequent rainfall events. Theseevents can add up to as much as 30 percentto 50 percent of annual precipitation(Schueler, 1987).

Benefits

Permeable paving can have many benefitswhen applied to redevelopment and infillprojects in urban centers. The most notablebenefits include:

! Groundwater recharge augmentation! Effective pollutant treatment for

sediment, metals, nutrients, chemicaloxygen demand and hydrocarbons(see pollutant removal performancetable)

! Aesthetic improvement to otherwisehard urban surfaces (lattice pavers)

! Less ponding of water on surface,resulting in reduced need for salt andsand applications in the winter

Limitations

Proper site selection is an important crite-rion when selecting this practice.

Partial or total clogging of the paving or un-derlying materials (such as woven geotextilefabrics) with sediments or oil during construc-tion or over the life of the pavement cancause system failure. The clogging problemcan be overcome by proper design and main-tenance. The following steps should be takento prevent against system failure:

! Be sure that pavement does notreceive runoff from areas that arelikely to contribute large sedimentloads and debris

! Do not install pavement adjacent toareas subject to significant winderosion

! Protect pavement from sedimentinputs during the construction phase

! Do not install pavement over highlycompacted soils

! Do not install pavement in areas thatreceive high vehicular traffic volumesand regular use by heavy vehicles(leading to subsoil compaction andreducing infiltration capacity)

! Use pretreatment practices such asvegetated filter strips where possible

! Follow all design and manufacturingspecifications for subgrade materialsas well as surface materials

Requirements for maintaining infiltration ca-pacity and effective pollutant removal in-clude:

! Routine vacuum sweeping and high-pressure washing (with proper dis-posal of removed material)

! Drainage time of at least 24 hours! Permeable soils! Pretreatment of runoff from site! Organic matter in subsoils! Clean-washed aggregate


Potential permeable paving sites need to beevaluated for the following criteria:

! Underlying soil permeability shouldbe between 0.5 and 3.0 inches perhour (up to 8.3 inches for sand).



! The bottom of the stone reservoirshould not exceed a slope of 5percent. Ideally it should be com-pletely flat so that the infiltratedrunoff will be able to infiltratethrough the entire surface.

! Permeable paving should be locatedat least two feet above the seasonallyhigh groundwater table, and at least100 feet away from drinking waterwells.

! Permeable paving should be locatedin low traffic and overflow parkingareas.

! The contributing drainage area shouldbe less than 15 acres.

! Infiltration practices shall be designedto exfiltrate the water quality volumethrough the floor of each practice.

Calculate the surface are of the underlyinginfiltration area as:

Source: Urban Environmental Design Manual


Ap = Vw / (ndt + fT/12)where:

Ap = surface area (f2)Vw = design volume (e.g., WQv) (ft3)n = porosity (assume 0.4)dt = trench depth (maximum of seven feet,and separated by at least three feet from sea-sonally high groundwater) (ft)fc = infiltration rate (in/hr)T = time to fill trench or dry well (hours)(generally assumed to be less than two hours)

Cost

Costs for permeable paving can be signifi-cantly more than traditional pavement, de-pending upon the materials used. However,the overall project costs are reduced whentaking into account savings from reduced tra-ditional stormwater infrastructure costs. Theestimated annual maintenance cost for a po-rous pavement parking lot is $200 per acreper year (EPA, 1999). This cost assumes fourinspections each year with appropriate jethosing and vacuum sweeping.

Maintenance

Depending on the type of permeable pavingand the location of the site, the maintenancelevel ranges from high to low. Areas that re-ceive high volume of sediment particles willclog more readily due to soil compaction.Concrete grid pavers and plastic modularblocks require less maintenance because theyare not clogged by sediment as easily as po-rous asphalt pavement. However, regardlessof the type of pavers used, the level of main-tenance and ultimately the failure rate is de-pendent on the location of the site. Properlyselected sites with permeable paving normallyrequire regular vacuum sweeping or high

pressure hosing two to three times per yearto remove sediments.

Open channels

Open channels are concave, vegetated con-veyance systems that slow down runoff flowand can improve water quality through infil-tration and filtering. When designed properly,they can be used to retain and pre-treatstormwater runoff. There are four differentcategories of open channels used instormwater management practices. Theseinclude grass channels, dry swales, and wetswales. Grass channels are modified drain-age channels that provide water quality treat-ment for small, frequent storm events. Flowrate is the principle design criteria for grasschannels. Dry swales have the same principlepre-treatment process as bioretention filters,which combine physical filtering and adsorp-tion with bio-geochemical processes to re-move pollutants. Dry swales are designed torapidly move water through a highly perme-able layer and then collect it by an underdrainpipe. Wet swales often incorporate checkdams, and act as long, linear shallow wet-land treatment systems. Wet swales occurwhen the water table is located very close tothe surface. Wet swales are designed to treator retain stormwater for a 24-hour period(�volume-based� systems). Proper vegetationselection is needed to ensure plant survival

Open channel system

Source: Portland Stormwater Management Manual



and channel stabilityfor both wet and dryswales.


Grass channels anddry/wet swales arerarely used to man-age large storms orto provide peak flowattenuation for theso-called �channelforming� storms (i.e,in the range of theone-year to 1.5-year

frequency return interval), or flood controlevents (i.e., 10-year to 100-year frequencyreturn intervals). Grassed channels accent thenatural landscape, break up impervious ar-eas, and are appropriate alternatives to curband gutter systems. They are best suited totreat runoff from rural or very low-densityareas and major roadway and highway sys-tems. They are often used in combination withother stormwater management practices toprovide pre-treatment and attenuation, butcan be used as stand-alone practices. Thedesign objective for grass channels is to main-tain a low flow rate in order to achieve a mini-mum residence time of 10 minutes. On-sitesoil characteristics determine whether a siteis suitable for grass channels designed for in-filtration. Grass channels have the same de-sign considerations that are applied to infil-tration basins and trenches: soil type, infil-tration rate, and separation to groundwaterand/or bedrock.

Dry swales are appropriate in areas wherestanding water is not desirable, such as resi-dential, commercial, or industrial areas andhighway medians. In dry swales, a prepared

soil bed is designed to filter the runoff forwater quality. Runoff is then collected in anunderdrain system and is discharged to thedownstream drainage system. The designobjective for dry swales is to drain down be-tween storm events within 24 hours. Wetswales are similar to stormwater wetlands intheir use of wetland vegetation to treatstormwater runoff. The water quality treat-ment mechanism relies primarily on settlingof suspended solids, adsorption, and uptakeof pollutants by vegetative root systems(Claytor & Schueler, 1996). Wet swales aredesigned to retain runoff for 24 hours. Theapplication of wet swales is limited due tostanding water and the potential problemsassociated with it, such as safety hazards,odor, and mosquitoes. The feasibility of in-stalling any open channel on a site dependson the local climate, the right soils to permitthe establishment and maintenance of a densevegetative cover, and available area. The con-tributing area, slope, and perviousness of thesite will determine the dimension and slopeof the open channels.

Benefits

The benefits of open-channel systems includeminimized water balance disruptions throughthe reduction of peak flows, the filtering andadsorption of pollutants, and increased re-charge. Other benefits include lower capitalcost relative to more structural stormwatermanagement practices, improved aestheticsbecause they accent the natural landscapeand break up impervious areas, and a netbenefit to the public in the reduction of ur-ban heat island effect.

Limitations

Open channels used in stormwater manage-ment are typically ineffective for water-qual-

Dry swales

Cla

ytor


ity treatment and are vulnerable during largestorm events. High velocity flows as a resultof these large storm events can erode the veg-etative cover, if the channels or swales arenot designed properly. Other limitations in-clude:

! Areas with very flat grades, steeptopography, and wet or poorly drainedsoils

! Wet swales are potential drowninghazards, mosquito-breeding areas,and may emit odor

! The land space required for openchannels ranges from 6.5 percent oftotal contributing impervious area forgrass channels and 10 to 20 percentfor dry and wet swales

! Pre-treatment is necessary to extendthe channel�s functional life, as wellas to increase the pollutant removalcapability. A shallow forebay at theinitial inflow point is recommendedas a pre-treatment component.


The general design of open channel systemsshould take into consideration the followingcriteria:

� Soils - for grass channels, the infiltratingcapability is a factor in locating swales. Swaleinfiltration rates measured in the field shouldbe between 0.5 and 5.0 inches per hour. Suit-able soils include sand, sandy loam, loamysand, loam, and silty loam. Highly permeablesoils provide little treatment capability, andsoils with low permeability do not provideadequate infiltration during the short reten-tion time. The soil bed underneath the dryswale should consist of a moderately perme-able soil material, with a high level of or-ganic matter.

� Shape - Open channel systems are usuallyparabolic or trapezoidal in shape. Parabolicswales are natural and are less prone to me-ander under low flow conditions. Trapezoi-dal swales provide additional area for infil-

Sourc

e: U

rban

Envi

ronm

enta

l D

esig

n M

anual



tration but may tend to meander at low flowsand may revert to a parabolic form. Trapezoi-dal sections should be checked against theparabolic sizing equation as a long-term func-tional assessment.

� Dimension - for grass channels, the sideslopes in the channel should be 3:1 or flatter.The longitudinal slope should be between 1and 4 percent for grass channels and 1 and 2percent for dry and wet swales. The minimumlength of a grass channel to ensure waterquality treatment is 600 feet. This is deter-mined based on the maximum flow velocityof one foot per second (fps) for water qual-ity treatment, multiplied by a minimum resi-dence time of 10 minutes (600 seconds). Thewet swale length, width, depth, and slopeshould be designed to temporarily accommo-date the water quality volume through sur-face ponding. To achieve surface ponding, itis usually necessary to install check dams aspart of a wet swale system. For a dry swale,

all of the surface ponding should dissipatewithin a maximum 24-hour duration.

� Vegetative Cover - Dense vegetative coverslows the flow of water through the swaleand increases treatment. Vegetation shouldbe able to tolerate being wet for 24 hours.The velocities in the open channel systemsshould not exceed the erosive levels for thevegetative cover in the channel. Once run-off rates and volumes are calculated usingan appropriate hydrologic model, the basicequation for sizing open channel systems issummarized below.

Cost

Open channel systems are cost-effective mea-sures relative to curb and gutter systems andunderground storm sewers. The base cost forgrass channels is 25 cents per square foot(SWRPC, 1991). Designed swales, such as adry swale with prepared soil and underdrain

Filter Strip Design Considerations

Prin

ce G

eorg

e�s

County

, M

d.


Grassed Swale Design Considerations

Prin

ce G

eorg

e�s

County

, M

d.

piping, have an estimated cost of $4.25 percubic foot (SWRPC, 1991). Relative to otherfiltering system options, these costs are con-sidered to be moderate to low. Most recentcost estimates have approximated $5 per lin-ear feet for grass channels and $19 per linearfeet for dry swales. The annual maintenancecost can range from 5 to 7 percent of theconstruction cost (SWRPC, 1991).

Maintenance

The life of an open channel system is directlyproportional to its maintenance frequency.The maintenance objective for this practice

includes keeping up the hydraulic and removalefficiency of the channel and maintaining adense, healthy grass cover. The following ac-tivities are recommended on an annual basisor as needed:

! Mowing and litter and debris removal! Stabilization of eroded side slopes

and bottom! Nutrient and pesticide use manage-

ment! De-thatching swale bottom and

removal of thatching! Discing or aeration of swale bottom! Every five years, the channel bottom



may need reshaping and removal ofsediment to restore original crosssection and infiltration rate, andseeding or sodding to restore groundcover is recommended

Maintenance for the grass channel consistsof annual inspections and correction of ero-sion gullying and reseeding as necessary.When sediment accumulates to a depth ofapproximately three inches, it should be re-moved and the swale should be reconfiguredto its original dimensions. The grass in theswale should be mowed at least four timesduring the growing season. The condition ofthe grass vegetation should be noted duringinspection and repaired as necessary. Dryswales should be inspected on an annual ba-sis and just after storms of greater than orequal to the one-year frequency storm. Boththe structural and vegetative componentsshould be inspected and repaired. When sedi-ment accumulates to a depth of approxi-mately three inches, it should be removed andthe swale should be reconfigured to its origi-nal dimensions. The grass in the dry swaleshould be mowed at least four times duringthe growing season. If the surface of the dry

swale becomes clogged to the point thatstanding water is observed in the surface 48hours after precipitation events, the bottomshould be roto-tilled or cultivated to breakup any hard-packed sediment, and then re-seeded. Trash and debris should be removedand properly disposed of.

Wet swales should be inspected annually andafter storms of greater than or equal to 2.8inches of precipitation. During inspection,the structural components of the pond, in-cluding trash racks, valves, pipes and spill-way structures, should be checked for properfunction. Any clogged openings should becleaned out and repairs should be made wherenecessary. The embankments should bechecked for stability and any burrowing ani-mals should be removed. Vegetation alongthe embankments, access road, and benchesshould be mowed annually. Woody vegeta-tion along those surfaces should be prunedwhere dead or dying branches are observed,and reinforcement plantings should beplanted if less than 50 percent of the origi-nal vegetation establishes after two years.Sediment should be removed from the bot-tom of the swale.

Schematic plan of a grass channel

Cla

ytor

& S

chuel

er,

1996


Plan and section of a dry swale

Hors

ley-

Witte

n G

roup



Hors

ley-

Witte

n G

roup

Plan and section of a wet swale


REFERENCES

Claytor, R. (2005). The Urban Environmen-tal Design Manual. Providence, R.I.: R.I. De-partment of Environmental Management.

Prince George�s County, Md., Department ofEnvironmental Resources. (1999). Low-Im-pact Development Design Strategies: An in-tegrated design approach. Largo, Md.: Author.

330. HYPOTHETICALSTORMWATER MANAGEMENT

University of New Hampshire StormwaterCenter. (2006). Rundown on Runoff:: TheUNH Stormwater Center's 2005 Data Report.Durham, N.H.: Author. <http://www.unh.edu/erg/cstev/pubs_specs_info/annual_data_report_06.pdf>.

Source: M. Leighly and J. Martel, Rhode Island School ofDesign, 2006.


Public Access

400. PUBLIC ACCESS IN THEURBAN COASTAL GREENWAY

410. UCG PUBLIC ACCESSREQUIREMENTS

To establish continuous public access alongthe Metro Bay shoreline is one of the overallobjectives of the Urban Coastal Greenway(UCG) policy. Per the R.I. Coastal ResourcesManagement Program (Section 335 of theRedbook), CRMC is responsible for ensuringthat public access to the shore is protected,maintained and, where possible, enhanced forthe benefit of all. The following points arethe public access standards in the Metro BayUrban Coastal Greenway policy for physicalaccess along and to the waterfront, as well asvisual access.

A. Primary (alongshore) publicaccess

All new multi-residential, commercial, andmixed-use developments should provide pub-lic access along their portion of the UCG. Incertain cases, the public access componentmay be allowed within the construction set-back or another portion of the site. The pri-mary path, however, should connect or beconsistent with existing municipal or state

pedestrian or bike path access paths and con-sider future pathway plans. Although CRMCwill allow pathways of up to 20 feet in widthwhen emergency vehicle access is necessary,primary public access pathways may be a mini-mum of 8 feet in width to accommodate pe-destrian and bicycle access.

B. Secondary (arterial orperpendicular) public access

Each design plan shall include at least one sec-ondary access path that emanates from a pub-lic place and leads to the primary public ac-cess path per 500 linear feet of shoreline. Thesecondary access path shall connect sidewalktraffic with the alongshore UCG path, and maybe a meandering path, as long as erosion isminimized. The access path should be a mini-mum of 8 feet in width to accommodate pe-destrian traffic, but may be as wide as 20 feetwhen emergency vehicle access is necessary.CRMC may waive the 500-foot secondarypathway standard if the applicant provides 10percent more public parking spaces than re-quired and can demonstrate that there is ad-equate available secondary public access.

Bold Point Park, East Providence, provides visualaccess to the Bay and to Providence.

Pawtucket Town Landing provides physicaland visual access to the Seekonk River.


C. Permeable pathways

All public access pathways must be con-structed of a pervious surface unless they willbe used for activities such as cycling and/oremergency vehicles where the pathway mayrequire a more permeable surface, or whereconsistency with existing adjacent impervioussurface paths (e.g., Waterplace Park) is re-quired. In these cases, paths shall be designedto ensure that runoff drains into vegetatedstormwater treatments to so that water doesnot pool and then erode the path surface or

adjacent soils. When paths are located directlyadjacent to the coastal feature, they should beangled slightly to cause stormwater runoff toflow inland for vegetative treatment, ratherthan toward the coastal feature. Approved veg-etative techniques are described in Chapter 3of this manual.

D. Areas with existing public access

Where existing public access pathways andpublic roads occur between the coastal fea-ture and the development parcel(s), the pri-mary public access and construction setbackrequirements may be waived. In addition,where public roads are immediately adjacentto the sides of the development perpendicu-lar to the coastal feature, these public roadsmay count toward the UCG secondary publicaccess requirements. The road(s) must be us-able for pedestrian and/or emergency vehicleaccess, as appropriate. This situation will oc-cur mostly within the UCG Inner HarborZone. In addition, CRMC may waive the 500-foot secondary pathway standard if the appli-cant provides 10 percent more public parkingspaces than required and can demonstrate thatthere is adequate available secondary publicaccess.

E. Emergency vehicle access

Through the primary and secondary accesspathways, each UCG design must include ad-

equate provisions for emergencyvehicle access paths from the near-est street to the shoreline (approxi-mately every 500 feet), as deter-mined in coordination with the mu-nicipality with jurisdiction. Thesevehicular paths shall be constructedof a permeable surface capable ofsupporting emergency vehicles.

Benches at Pawtucket Town Landing are located on apervious surface.

Seaview Park, Cranston, provides amenitiesfor enjoying the Bay.


Public Access

F. Sharing public access amongadjoining parcels

Adjoining parcels may share secondary pedes-trian or vehicular access paths on their sharedboundary, where applicable, as long as thereis at least one secondary pathway per 500 feetof shoreline.

G. Public access parking

Each development shall include a minimumof two public parking spaces adjacent to anaccess point, and an additional space per 100feet of linear shoreline (where �linear� refersto the shortest distance between lot bound-aries) within the parcel. Adjacent on-streetparking and off-street public parking may beconsidered by CRMC as satisfying the publicparking requirements. The placement of thepublic parking spaces shall be decided in con-sultation with the CRMC and the municipal-ity of jurisdiction. In cases where the projectis directly adjacent to public parking, (definedas on-street parking and off-street parkingavailable to the general public), such spacesmay be included for purposes of satisfying thepublic parking requirements of this section,provided they are within 200 feet of the per-pendicular public access path and have a rea-sonable vacancy rate.

H. Compliance with the Americanswith Disabilities Act

Public access paths and associated elementsmust be compliant, where applicable, with themost recent version of the Americans withDisabilities Act (ADA) Standards for Acces-sible Design (www.usdoj.gov/crt/ada/stdspdf.htm).

I. Public access enhancement as apossible compensation measure

An applicant may propose to increase oppor-tunities for public recreational use of coastalwaters on the development in place of com-pensation for a reduction in the required UCGwidth. This might include enhancement of thepathway through the placement of benches,lookout points, bicycle paths, fishing piers orplatforms, public canoe or kayak racks, fishcleaning facilities, or interpretive signage. Thisoption does not include construction of ma-rinas.

420 MEETING UCGREQUIREMENTS

Both physical (pedestrian or bicycle) and vi-sual access to the Bay should be consideredduring the initial stages of design. Althoughin most cases the physical public access shouldbe located within the UCG, by consideringbuilding massing and viewscapes duringproject design, visual access may be achievedfrom distances beyond the scope of the UCGand can be accomplished through thoughtfulsite planning and design, including roadwaylayout, building siting and massing, and useof intrinsic opportunities at the site, such asnatural grade changes and shoreline variations.

This Bay shoreline is accessed from the park-ing lot at Richmond Square, Providence.


Site planning for public access

In order to determine the best and most ap-propriate locations for public access and toensure that the public access areas relate tothe scale and intensity of the proposed devel-opment, a site analysis should be preparedprior to developing schematic designs. Thisprocess encourages the developer to considerthe inclusion of public access as one of theprimary design elements, as opposed to it be-ing an afterthought, and to ensure that it re-lates directly to the context of the site as wellas to the region. Site analysis considerationsshould include the proposed use of the site,the topography of the site and the contourof the shoreline, if the site has any significantnatural or cultural features, the surroundingbuilt and natural environment, and the adjoin-ing existing and proposed uses (e.g. industrialor neighborhood). The view of the water fromthe land, and toward the land from the water,should also be considered and cultivated whenplanning and designing public access areas.

Techniques for developing qualitypublic access

The following additional information will as-sist the developer in creating public access thatboth meets the UCG public access objectiveas well as enhance that particular Metro Bay

parcel. This information is based on the Shore-line Spaces: Public Access Design Guidelinesfor the San Francisco Bay ( www.bcdc.ca.gov/pdf/planning/PADG.pdf) and modified toprovide guidance for the Metro Bay region.

A. Provide connections andcontinuity along the shoreline

Access areas are utilized most if they providedirect connections to public rights-of-waysuch as streets and sidewalks, are served bypublic transit and are connected to adjacentpublic access or recreation areas. This can bedone by:

! Providing clear and continuoustransitions to adjacent developments

! Connecting shoreline public accesswith the municipalities� park and openspace systems, public buildings,shopping districts, and other publicspaces

! Coordinating shoreline public accesswith state agencies and local munici-palities to provide for connections totrail and public use areas that may beplanned for the future. Some of theseplans include the Rhode IslandGreenspace and Greenways Plan, theBlackstone River Bikeway, theWoonasquatucket River Greenway, andthe East Coast Greenway.

! Using local public street networks toinform shoreline site design and toextend the public realm to the Bay

! Providing connections perpendicularto the shoreline at regular intervals tomaximize the opportunities foraccessing and viewing the Bay

! Promoting safe pedestrian and bicycleaccess to the Bay by calibrating trafficlights at nearby intersections andproviding safe, enhanced crosswalks

East Providence offers parkingadjacent to the East Bay Bike Path.


Public Access

! Conveniently and directly connectingshoreline developments to transitsources such as water taxis, ferries,buses and rail systems

B. Make public access usable

The pubic access amenities offered shouldcorrespond with the suitable uses of the site.While some shoreline areas are best suited forquiet and contemplative public spaces, otherslend themselves to be used for large publicgatherings, such as festivals. . Existing site char-acteristics and opportunities, such as fishing,viewing, picnicking, or boating, should be capi-talized on in designing public access spacesthat are safe and secure. Other techniques tomake public access usable include:

1. Gathering and seating areas

! Provide gathering places, such asplazas, that function as focal areaswithin larger public access areas.

! Provide plenty of seating choices-some of which are shaded- such asfixed benches and chairs, picnic tables,retaining walls, planter seats, grassberms, steps, and moveable chairs.

! Provide elevated places for viewingthe Bay.

! Orient seating toward Bay views orvistas of opposite shores or land-marks, such as bridges or towers.

! Provide durable site furnishings tominimize maintenance requirements.

! Provide enough lighting to create asense of safety, but design to controlintensity, glare and spillover

2. Signage

Provide clear and understandable signs areposted in public access areas that: 1) informthe public where public access areas are lo-cated and how to reach them, including park-ing; 2) describe the recreational opportunitiesare available nearby: 3) describe how the pub-lic can use the area, consistent with rules gov-erning appropriate behavior; 4) and providethe interpretation of natural, historic and cul-tural features in or near the public access ar-eas. Some other considerations include:

! Install the CRMC UCG sign withinthe UCG public access areas

! For larger developments, a compre-hensive sign program should beimplemented

! Provide wayfinding signs to assistshoreline users in traveling to andalong the Bay! Provide management signs inwildlife areas that describe environ-mental sensitivity and/or any rules andrestrictions associated with the man-agement of the wildlife area! Do not locate advertising signagein public access areas! Use the same design in everyapplication so that public access areasare easily identifiable by members ofthe public! Select and install signs that are inscale with the environmentCorliss Landing, Providence, offers amenities for

viewing the Bay at the hurricane barrier.


3. Shoreline edge treatments thatprovide closeness to the water

! Tidal stairs provide visitors with asimple means of getting close to thewater. However, algae growth usuallyoccurs below the Mean High Tideline, creating slippery conditions.Therefore, careful considerationshould be given to facilities proposedlower than where algae normallyoccurs.

! Tidal ramps provide a means foraccess into the water, especially forwindsurfers and persons with disabili-ties

! With careful placement of appropri-ately sized rock and stone, riprap canbe designed to include seating ele-ments, providing closeness to the Bay

! Sandy beaches provide simple andconvenient access to the water forhuman-powered watercraft andswimmers

! Low-profile floats and docks providesafe launching and landing conditionsfor human-powered watercraft, such ascanoes and kayaks; these should beappropriately sited to avoid traffic andwater safety hazards

! Piers and overlooks provide closenessto the water by enabling users to getout over the water

4. Pedestrian and vehicular railings

! Design guardrails to allow maximumviews, especially on bridges

! Design guardrails and handrails thatrelate to the architectural or landscapestyle of the public access area

5. Fishing facilities

! Design fishing facilities, such as piersand fish cleaning stations that accom-modate people with disabilities

! Post public information about poten-tial fishing hazards, such as boatingconflicts or health considerations helpto keep the public safe

6. Point access at port and water-related industrial areas

! Provide the public with opportunitiesto safely view port activities and theoperations of water-related industry,such as oil terminals and marineconstruction facilities

7 Interpretive elements and public art

! Consider including interactive siteelements or interpretive signs to allowpeople to more fully appreciate thenatural, cultural, or historical assets ofthe site and the Bay

! Public art that complements the Bay

This path offers visual accessto the WoonasquatucketRiver at Eagle Square,Providence


Public Access

setting adds visual interest to theshoreline

C. Provide, maintain, and enhancevisual access to the Bay andshoreline

Northern Narragansett Bay is a scenic resourcethat contributes to the enjoyment of daily lifefor many Rhode Islanders. CRMC, as de-scribed in section 330 in the Redbook, has aresponsibility to preserve, protect, and, wherepossible, restore the scenic value of the coastalregion to retain the visual diversity and uniquevisual character of the Rhode Island coast.

Probably the most widely enjoyed �use� ofthe Bay is simply viewing it and the activitiestaking place on it from the shoreline, from thewater, or from a distant viewpoint. CRMCmaintains that views to and across the waterthrough yards, between buildings, and fromroadways should be preserved and, where pos-sible, created. Techniques to enhance visualaccess can be achieved by:

! Locating buildings, structures, parkinglots, and landscaping of new shorelineprojects such that they enhance anddramatize views of the Bay and theshoreline from public thoroughfaresand other public spaces

! Organizing shoreline development toallow Bay views and access betweenbuildings

D. Maintain and enhance the visualquality of the Bay, shoreline, andadjacent developments

Factors that contribute to the visual qualityof the shoreline and adjacent developmentsinclude:

! Landscaping with native and drought-

tolerant plants to provide texture andinterest to the waterfront

! Improving existing degraded shorelineedges and substandard shorelineerosion protection

! Removing litter and debris that marsthe appearance of the shoreline

! Providing visual interest and architec-tural variety in massing and height tonew buildings along the shoreline, andsetting back uses that do not comple-ment the Bay so they do not impactthe shoreline

Some techniques to achieve this include:

1. Shoreline planting

! Control landscaping to preserve anddramatize Bay views, especially in sideyards, at street ends, in parking lots,and along public thoroughfares

! Provide a hierarchy of plant types andsizes within a project that relates tothe shoreline, public spaces, andadjacent developments

! Use native plants that provide habitatfor wildlife wherever possible andappropriate. For specific plantingrecommendations, refer to the mostcurrent edition of the CRMC/URI

Public access at the end of NarragansettBoulevard, Cranston, overlooks StillhouseCove, the Rhode Island Yacht Club, andthe Providence River.


Coastal Plant list (www.crmc.ri.gov/pubs/pdfs/uri_plantlist.pdf)

2. Shoreline erosion control

Structural shoreline protection facilities aredefined as structures that control the erosionof coastal features, according to Section 300.7in the Redbook. Examples of these includerevetments, bulkheads, seawalls, groins, break-waters, and jetties. Non-structural methods forcontrolling erosion such as stabilization withvegetation and beach nourishment are stronglypreferred by CRMC. Riprap revetments arefavored to vertical steel, timber, or concreteseawalls and bulkheads except in ports andmarinas. When structural shoreline protectionis proposed, CRMC shall require that theowner exhaust all reasonable and practical al-ternatives including, but not limited to, therelocation of the structure and nonstructuralshoreline protection methods. Refer to Sec-tion 300.7 of the Redbook for more guidanceon this topic.

E. Take advantage of the Baysetting

Development along the shores of the Bayshould take maximum advantage of the attrac-tive setting that the Bay provides. Some waysto achieve this are by:

! Orienting the development to Bayviews and providing physical connec-tions to the Bay at every opportunity

! Orienting public access areas andimprovements to take advantage ofviews of opposite shores, landmarks(such as islands and bridges) andadjacent maritime activities such asboat launching, gas docks, ferrylandings, or other marine-related uses

! Utilizing the shoreline for Bay-related

uses, and setting uses, such as parkinglots, that do not complement the Bayor require a Bay setting, well backfrom the Bay and design and managethem so as to not impact the shoreline

F. Ensure that public access iscompatible with wildlife throughsiting, design, and managementstrategies

In many locations around the Bay, the shore-line edge is a vital zone for wildlife. These ar-eas are primarily located within the UCG zonecalled Area of Particular Concern. Access tosome wildlife areas allows visitors to experi-ence and appreciate the Bay�s natural resourcesand can foster public support for resourceprotection. However, in some cases, publicaccess may have adverse effects on wildlife,and may result in adverse long-term popula-tion and species effects. The type and severityof effects, if any, on wildlife depend on manyfactors, including site planning, the type andnumber of species present, and the intensityand nature of the human activity. Take intoconsideration these issues by preparing a siteanalysis to generate information on wildlifespecies and habitats existing at the site andthe likely human use of the site and then em-ploying appropriate siting, design, and man-agement strategies (such as buffers or use re-strictions) to reduce or prevent adverse hu-

Corliss Landing


Public Access

man and wildlife interactions.

Other techniques include:

! Use design elements such as varyingtrail widths, paving materials, and siteamenities to encourage or discouragespecific types of human activities

! Use durable materials to reduceerosion impacts on adjacent habitatsand to keep users from creatingalternate access routes

! Provide spur trails to reduce informalaccess into and through more sensitiveareas

! Locate parking and staging areas awayfrom sensitive habitat areas

! Locate night lighting away fromsensitive habitat areas

! Use physical design features to bufferwildlife from human use

! Manage type and location of publicuse to reduce adverse effects onwildlife

! Incorporate educational and interpre-tive elements

Managing public access

CRMC permits will require that public accessareas will be used properly, managed for the

public�s safety and enjoyment, and reasonablymaintained. The following are some commonrequirements for managing public access ar-eas:

A. Responsibility for public accessareas

Once a CRMC permit is issued, the permitteeis typically responsible for ensuring that thepublic access area and associated improve-ments are installed, used, and maintained inaccordance with the permit. Public access ar-eas are often required to be dedicated to apublic agency or otherwise permanently guar-anteed, usually through a legal instrument, forthe exclusive use by the public. In accordancewith R.I.G.L. 32-6-5(c), limited liability applieswhen the CRMC stipulates public access as apermit condition and when the council desig-nates a public right-of-way to the shore.

B. Uses within public access areas

Shoreline spaces that are dedicated as publicaccess areas are typically made available ex-clusively to the public for unrestricted uses,such as walking, bicycling, sitting, viewing,fishing, picnicking, kayaking, and windsurfing.If someone wishes to use the public accessarea for uses other than those specified by the

CRMC permit, prior written ap-proval by or on behalf of CRMC isusually required.

C. Maintenance of publicaccess areas

CRMC may require a public accessmaintenance plan that describes thelandowner�s plans to repair all pathsurfaces; replacement of any land-scaping that dies or becomes un-kempt; repairs or replacement of any

A path starting at Irving Avenue, Providence,leads to the Bay.


530. HYPOTHETICAL PATHWAY DESIGN

REFERENCES

Shoreline Spaces: Public Access Design Guidelinesfor the San Francisco Bay. (2005). San FranciscoBay Conservation and Development Commis-sion.

public access amenities such as seating areas,restrooms, drinking fountains, trash contain-ers, and lights; periodic cleanup of litter andother materials deposited within the accessareas; removal of any hazards in or encroach-ments into the access areas; and assuring thatpublic access signage remains in place and isclearly visible. To reduce ongoing maintenancerequirements, public access areas should bebuilt with durable materials and using high-quality construction methods. Pawtucket Town Landing

Source: M. Leighly and J. Martel, Rhode Island School of Design, 2006.

J. LaClair, B. McCrea, and Hunt Design Asso-ciates. (2005). Shoreline Signs: Public Access SignageGuidelines. San Francisco Bay Conservation andDevelopment Commission.


Appendix I

APPENDIX I. METRO BAY SHORELINE SIGNS

Much of the information in this section hasbeen adapted from the San Francisco Bay Con-servation and Development Commission�sShoreline Signs: Public Access Signage Guidelines(2005).

These guidelines on public access signage fordevelopment or redevelopment projects alongthe Metro Bay shoreline will assist CRMCpermit holders in meeting the signage require-ments specified in their permits.

URBAN COASTAL GREENWAY SIGNS

The Metro Bay Urban Coastal Greenway signis intended to be used consistently in publicaccess areas around the Metro Bay as a readilyrecognizable sign that informs visitors of tehlocation and access to the Urban CoastalGreenway.

How to get the signsArtwork for the Metro Bay Urban CoastalGreenway sign is available from CRMC at(401) 783-3370. Signs may be fabricated by signmanufacturers. CRMC will provide some, butnot all, required signs. See below section onuse of the sign for more information.

Use of the Metro Bay Urban CoastalGreenway signIt is important that the Metro Bay UrbanCoastal Greenway sign appear the same wayin every application so that public access ar-eas are easily identifiable by the public.

!!!!! PlacementPrimary Urban Coastal Greenway signs mustbe placed at each perpendicular point that al-lows the public to get to the greenway. Sec-ondary Urban Coastal Greenway signs must

be placed along the greenway to assist thepublic in staying on the path. Secondary signsmust be placed at each property boundary thatintersects the greenway, and at 200-foot inter-vals along the greenway. In the case of prop-erties narrower than 200 feet, secondary signsmust be placed at property boundaries with aminimum of one secondary sign in the middleof the greenway on that property. Propertyowners are responsible for obtaining primaryUrban Coastal Greenway signs. CRMC willprovide a minimum of one secondary sign perproperty.

!!!!! MaterialsSigns may be made of any one of a variety ofrigid, durable materials, including porcelainenamel, aluminum, acrylic, or phenolic resin.

!!!!! GraphicThe graphic may be applied to the panel inany number of recognized signage techniques,including silk screening, digital printing, por-celain enamel image, or phenolic resin image.Do not hand paint or hand letter signs. Donot modify the proportions of the sign de-sign. New sign types and designs should bedeveloped in consultation with CRMC staff.

!!!!! MountingSigns may be firmly mounted on fences, walls,posts, or projected off surfaces (blademounted). While it is preferred that the signsbe mounted with concealed fasteners, boltingthrough the sign is acceptable. The size ofvisible bolt heads should be minimal. Do notbolt through lettering or symbols.


Sign artwork by Grady Peck.

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!!!!! SpecificationsThe primary greenway sign measures 18 inchesby 24 inches horizontal. Secondary and park-ing signs measure 9 inches by 12 inches hori-zontal. Materials for sign faces should be ofthe highest quality available. Inks and screenpaints should be fade resistant for a minimumof five years. Fasteners should be tamper-proof. Corners of sign panels should be easedto eliminate sharp edges. Wooden posts shouldbe No. 2 foundation-grade redwood, pressuretreated douglas-fir larch or better. Steel postsshould be hot-dipped galvanized to conformto ASTM A 123.

INTERPRETIVE SIGNS

DescriptionInterpretive signage is permanently postedinformation about local history, natural fea-tures, or events that enhance the visitor expe-rience. Developers and operators of publiclyaccessible shoreline properties are encouragedto create and implement such displays, therebyadding value to public shore visits.

Content GuidelinesThe best interpretive displays are usually basedon a series of simple but interrelated topicsor stories. Each individual display should fo-cus on a single topic; a series of closely lo-cated displays can illuminate various aspectsof a subject. For example, two or three dis-plays at a location can present related singletopics such as the location�s commercial his-tory, social history, or environmental signifi-cance.

!!!!! TextAppropriate and interesting text is important.Whenever possible, engage a professionalwriter to create short, compelling paragraphs.

Design GuidelinesInterpretive planners have found that illus-

trated panels, mounted on posts and parallelto pedestrian paths, are the most effective wayof attracting usage. This �wayside� designapproach is found in national parks and his-toric sites throughout the United States. Pan-els are mounted low and at an angle to allowviewing while not disturbing the scenic view.

!!!!! ArtworkIllustrations can vary from historic photo-graphs to specially commissioned illustrationsor diagrams. Color can be an effective tool fororganizing information and attracting atten-tion.

!!!!! LayoutPanel design and layout is best kept simplewith a short topical headline or title placed atthe top and illustrations or text arranged be-low, magazine style. Short captions for illus-trations can enhance interest and engage thereader.

!!!!! AccessibilityInterpretive signs should be designed to en-sure that people with disabilities or thosespeaking other languages, including Braille, canunderstand the message. For assistance in de-signing accessible signs, please see TheSmithsonian Guidelines on Accessible Exhi-bition Design at www.si.edu.

Representative design and topographic guide-lines as well as good examples of interpretivesigns are available from the National Park Ser-vice at www.nps.gov/hfc/products/waysides/contents.htm.

AREA MAPS

PurposeArea maps help visitors find their way alongthe shoreline. Designed correctly, maps canenhance a public shoreline visit by presenting


Urban Coastal Greenway sign height and placement options for public access signs.

Urban Coatal Greenway public access parking signs.

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geographic context. All developers and opera-tors of publicly accessible shoreline proper-ties are encouraged to create and install areamaps.

Content GuidelinesArea maps should be centered on the sitewhere the map is located, should describe theshoreline and immediate inland areas withinan approximately three- to five-mile radius ofthe site, should include points of interest thatfall within the area of the map and a small keymap or overview of the larger area, highlight-ing the areas shown on the main map. Mapsshould have a scale and provide informationabout walking times and distances betweenpoints of interest.

Design GuidelinesA simple, clear art style is best with bold linesfor trails. Incorporate symbols or pictographswhere possible to reinforce meaning.

Accessibility GuidelinesLettering should be clear and large enough forreading by most people.

Placement GuidelinesMaps should be mounted low and at an angleto allow viewing while not disturbing the sce-nic view.

Representative design and typographic guide-lines as well as good examples of maps areavailable from the National Park Service atwww.nps.gov/hfc/products/waysides/contents.htm.

REFERENCES

Shoreline Spaces: Public Access Design Guidelinesfor the San Francisco Bay. (2005). San FranciscoBay Conservation and Development Commis-sion.

J. LaClair, B. McCrea, and Hunt Design Asso-ciates. (2005). Shoreline Signs: Public Access SignageGuidelines. San Francisco Bay Conservation andDevelopment Commission.


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