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Zoning Commission Packet 2010 05-26-10 United City of Yorkville '`'` 800 Game Farm Road EST. , _ 1836 Yorkville, Illinois 60560 .4 Telephone: 630-553-4350 a p� Fax: 630-553-7575 C <tE '►ww AGENDA ZONING COMMISSION MEETING Wednesday, May 26, 2010 7:00 P.M. Parks & Recreation Administration Office 201 W. Hydraulic 1. Welcome 2. Approval of February 24, 2010 meeting minutes 3. Introduction of new Communi . Development Director, Kasti J. Barksdale-Noble 4. Review of Zoning Ordinance Update progress and timeline a. Background and brief discussion of sections reviewed and updated. 5. Continued Review of Zoning District, Conservation Design District Draft a. Discussion of modifications and additional research materials provided 6. Discussion of Downtown Rt. 47 overlap 7. Next meeting date: June 23, 2010 Pagel of 3 DRAFT UNITED CITY OF YORKVILLE ZONING COMMISSION Wednesday, February 24, 2010 7:OOpm City Hall Conference Room Board Members in Attendance: Michael Crouch,Chairman Gary Neyer Jeff Baker Al Green Greg Millen Phil Haugen(7:10) Pete Huinker(7:15) Absent: Ralph Pfister City Officials in Attendance: Bari Olson,City Administrator Laura Schraw,Interim Community Development Director Paul Zabel,Building Code Official Guests: None Meeting Called to Order Chairman Michael Crouch called the meeting to order at 7:05pm. Roll Call Roll call was taken and a quorum was established. Previous Meeting Minutes: Sentember 23,2009 and October 28.2009 September 23,2009 minutes were approved as read on a motion by Jeff Baker and second by Al Green. Approved by unanimous voice vote. October 28,2009 minutes were approved as corrected on a motion by Al Green and second by Jeff Baker, with the stipulation that the specific items noted within the minutes as to be clarified/confirmed by Travis Miller will be re-discussed after the new Community Development Director is hired.Approved by unanimous voice vote. New Business: 1. Status of search for Community Development Director Bart Olson stated that the final interview has been completed;no formal offer has been tendered yet.He expects to have the new person on board mid to late April 2010.There were fifty candidates,with roughly half from out of state.Eleven individuals were interviewed in the first round;four in the second round,and the final interview was with the Economic Development Committee, the Plan Commission Chairman,and the Zoning Board of Appeals Chairman. Page 2 of 3 Discussion Bart Olson asked if the committee wants to meet again before the new Community Development Director comes on board.Jeff Baker stated that he would like the new director on board before this committee goes too much farther with this process,so that het she can assist;Michael Crouch agreed.The committee agreed to not meet in March,but to wait until the last Wednesday in Aprit,so that the new director can attend the next meeting. 2. Review of Zoning District,Conservation Design District Draft Laura Schraw stated that the Land Use Plan from the Comprehensive Plan and also the Conservation Design District Ordinance Draft have been added into the meeting packet to reference.Michael Crouch stated that this Land Use Plan states the types of land uses which are allowable;what this committee decides should reflect what the Comprehensive Plan is calling for. Discussion Laura Schraw was asked to give an introduction to conservation design principles,and At Green stated that one review of the Conservation Design District Draft has already been completed.Conservation design examples are clustering,using a site's natural features,lack of curbs and gutters,swales,and rain gardens. This Ordinance mentions conservation of land includes active or passive recreational use. Jeff Baker brought up the Plan Commission's"10 Percent Rule"cap for multi-family structures.Mr.Baker and Mr.Crouch stated that development approval checklists used to be completed by them,but now City staff is completing these and providing reports to the various commissions and committees. Gary Neyer inquired if districts are laid out within a Comprehensive Plan in accordance with property tax/ financial analysis.Bar(Olson said no,and further stated that a comprehensive plan fiscal impact analysis is rare; the cost is approximately$50,000. Mike Crouch stated that there has always been considerable discussion regarding how big residential lots should be; Bart Olson said that this is relative to conservation design: the land use pattern and zoning is set, and now the issue is to maintain the density,but perhaps shift it around to accommodate for conservation design.This used to be referred to as"clustering",but is now commonly known as"low impact development".Pete Huinker stated smaller lots mean less roads and less infrastructure if they're clustered and the remainder of the development is used as open space(some as park/turf grass for playing on;some for conservation). Jeff Baker inquired as to who maintains a"natural setting';Mike Crouch stated that if the plan deviates from an"untouched"state, then it needs to be maintained.Ms.Schraw stated that this draft does stipulate that the designated owner is responsible for any maintenance,but that it would be beneficial to add language allowing designation of a Conservation Easement,so that the use of the property cannot be later altered. Section 10-10-1 (Purpose&Intent),Subsection"C"was discussed;does the language as stated mean that a working farm is allowed as part of a development's conservation area;the thought was that this was not the intent.There should be a buffer in between a working farm and residential properties,such as berms/open space/frontage roads.However,the practice of combined agricultural/residential use is increasing-a development in Hampshire,Illinois has a development with large homes and lots,and equestrian elements. Bart Olson inquired if a development's natural area is a working farm field,would that be an acceptable end- use as per this committee's conservation design guidelines?The consensus was that it ultimately depends on the surrounding uses-for example,whether it's a dry basin which requires maintenance.Mike Crouch stated if it's a use requiring no maintenance,that would be best.Pete Huinker suggested adding language stating that minimum acreage to be allowable for production farming. Ms. Schraw stated that the current Landscape Ordinance requires every new development to have their basins naturalized,unless a variance for site constraints is sought.The Storm water Maintenance Plan presented to City Council requires the City to work with HOA's to educate them on how to re-naturalize their basins;this is separate from Conservation Design,which is looking at new land use,and reducing the impact of that area.To an extent,one needs to maintain the overgrowth of invasive species which choke out the diverse habitat,and the specifications to do this are called out in the Landscape Ordinance and Park Page 3 of 3 Development Standards.Ms. Schraw currently performs the site inspections,and provides a report to the developer. Gary Neyer stated that for a developer to desire to apply conservation design to a project, there needs to be an economic incentive and density bonus,based upon the quality of the conservation space being provided. Mr.Crouch feels there should be a minimum quantification of principles applied, instead of simply stating a developer should"encourage innovation"and"provide greater efficiency". Mr.Neyer inquired as to how a conservation district would show up on the Comprehensive Plan Map;Ms, Schraw stated this would be an alternative in zoning use,and it was agreed that it's similar to a PUD. A question was raised regarding whether these standards were incorporated into the Subdivision Control Ordinance;Ms. Schraw stated that the Subdivision Control Ordinance states BMP's(Best Management Practices)should be applied,and that the Conservation Design ordinance is a"step up"From the Subdivision Control Ordinance.Perhaps after this ordinance is complete,the Subdivision Control Ordinance should be reviewed,but the Engineering Department should be consulted to see if the items proposed in this Ordinance are passed,would this type of development be approved at the time of site plan review?Mr.Huinker reminded that Public Works should be consulted as well,as they're going to ultimately inherit care and maintenance of the Right-Of-Way.Mr.Crouch reminded the group that this Ordinance should reflect what the public wants. Jeff Baker inquired if the intent of this Ordinance is to apply to new developments only;Ms.Schraw stated that Homeowner's Associations which seek assistance re-developing or returning their basins to a natural state are discussed on a case-by-case basis.Bart Olson stated those improvements would be governed by the City's Landscape Ordinance; this Ordinance is relative to new developments only. 3. Discussion of Downtown Route 47 Overlay Map Laura Schraw brought two maps to the meeting,showing the area between Walnut and Main Streets;one shows zoning and the other shows the overlay of Route 47,so that the width of the road and the extent of the improvements can be seen. Discussion Mr.Crouch stated that the maps were requested was so that the Zoning Commission could see how the Route 47 improvements were going to impact the properties adjacent to the roadway.They would like to see the ten-foot long map the Engineering Department has,showing what easements would be requested from property owners,what has been acquired and demolished,and what will be acquired and demolished.This could be used as a tool when owners adjacent to Route 47 apply for zoning changes.They would like to see a map of Route 47,from Rte.34 south to Rte.71.Ms.Schraw stated this will be brought to the next meeting. Additional Business: Going forward, the meetings will be held at the Parks&Recreation building located at 201 W.Hydraulic Street,in the old Post Office building. Adjournment: There was no further business and a motion was made by Mr.Crouch to adjourn the meeting.Mr.Huinker seconded the motion.Meeting adjourned at 8:56pm. Minutes respectfully submitted by Jennifer Woodrick Unified City of Yorkville Zoning Ordinance Update — Process Timeline REVISED TASK 2009 1 2010 MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. I JAN. FEB. MAR. APR. MAY I Zoning Commission Kick-Off meeting I � I Phase I —ASSESSMENT I I I I • Zoning Commission Review and Input on Assessment , • Zoning Commission meeting #2 April 29, 2009 I I I I Phase II — DOCUMENT CONTENT AND FORMAT I • Identify any new Zoning Districts necessary to create I • Identify the regulatory chapters/sections of the document I I L • Determine the style(s) of the document • Steering Committee Review and Input on Content & Fonnat I • Steering Committee meeting #3 May 27, 2009 I I I I I I Note: Public eview Meeting 1Presentations ill be schedul during this peri to obtain pubs c input Phase III —DOCUMENT DRAFTING I • Review of Conservation Design Techniques I I I I I I I • Commission Review and Input on Conservation Design • Commission meeting #4 June 24, 2009 • Preparation of Administrative Sections • Commission Review and Input on Draft j 1 • Commission meeting #S July 22, 2009 I I , ` I • Preparation of Draft Definition of Use Sections Ifj • Commission Review and Input on Draft I I I I • Commission meeting #6 August 26, 2009 I I I I I • Refinement of Definitions and Uses I I 1= = • Corninission Review and Input on refinements I • Cozninission meeting #7 September 23, 2009 I I I I I I 1 • Commission Review of draft ordinance • Commission meeting #8 October 28, 2009 I I I I I I I I I I f • Prepare Review final draft of Ordinance • Corn mission meeting #9 January 27, 2010 I I I I I I Phase IV--ADOPTION I I l # I I 1 I I • Public Hearing I • Economic Dev. Committee Review and Recommendation I I • City Council Review and Final Consideration I January 6,2010 CHAPTER 10 Conservation Design District 10-10-1: PURPOSE AND INTENT: The purpose of this chapter is to provide for an alternative zoning procedure for conservation design developments that provide value to the community and the environment over the conventional zoning district and which is consistent with the comprehensive plan and intent of the zoning ordinance.Conservation Design Developments(CDD) are intended to encourage the most imaginative and best possible design of building Forms and site planning for tracts of land where unitary plans would best adapt to topographic and other natural features of such sites. The Conservation Design Development district purpose is to: A.Conserve undeveloped land for the purpose of protecting primary and secondary conservation areas in contiguous,un-fragmented,commonly managed landscape to; 1. Protect large,intact wildlife habitat areas and connect patches of wildlife habitat to support greater biodiversity,maintain ecosystem processes and allow larger,healthier populations to exist;and 2. Minimize edge conditions and associated colonization by invasive plant species. B.Contribute to the creation of a community wide greenway system for the benefit of present and future residents; C. Protect productive agricultural soils for continued or future agricultural use by conserving areas of land large enough to allow for efficient farming operations; D.Encourage innovation and promote flexibility,economy,and ingenuity in development; E. Provide for the conservation and maintenance of greenway land and for active or passive recreational use by residents; F.Provide greater efficiency in the siting of services and infrastructure,including the opportunity to reduce length of roads,utility runs,and the impervious cover required for residential development; G. Protect water quality and reduce erosion and sedimentation by retaining existing vegetation and minimizing development on steep slopes; H.Implement land use,open space,and community policies set forth in the United City of Yorkville's Comprehensive Plan. 10-10-2: PERMITTED AND SPECIAL USES: Refer to Chapter 6 of this Title. 56 10-10-3: DIMENSIONAL STANDARDS: Conservation Design Subdivisions are expressly exempt from the lot area, lot width,yard area,and lot coverage requirements of the Zoning Ordinance. Lots must be of a size and shape to allow for compliance with applicable building codes and to provide for high-quality living environment for subdivision residents. Lots immediately abutting or within 150 feet of an existing or approved subdivision may be no smaller than 80%of the average lot size within the adjacent subdivision. 10-10-4: MAXIMUM BUILDING HEIGHT: A. One-and Two-Family detached dwellings: Forty feet(40')and not more than 2.5 stories,whichever is less B. Single Family Attached&Multiple Family dwellings: Eighty feet(80')and not more than six(6)stories, whichever is less. 10-10-S: DEVELOPMENT STANDARDS: A. Maximum Development Potential 1. Base Density: L The United City of Yorkville's Comprehensive Plan land use classifications sha[[be used to determine base densities: Land Use Classification Maximum Base Density (dwelling units per acre) Rural Neighborhood 0.5 Estate Neighborhood 1.5 Suburban Neighborhood 2.0 ii. If the conservation design subdivision is located in more than one land use classification, the maximum number of dwelling units allowed must be determined separately for each portion of the site lying within a different land use classification. Density may be transferred from one portion of the site to another,provided that such transfers do not result in an increase in the number of dwelling units allowed on the overall site. 2. Dwelling Unit Yield Formula(Pre Bonus) L Determine Base Site Area 1. Determine Gross Site Area 2. Subtract Right of Way(existing and ultimate) 3. Equals BASE SITE AREA ii. Determine Buildable Area 1, BASE SITE AREA 2. Subtract Regulated wetlands and wetland buffers 3. Equals BUILDABLE AREA iii. Determine Net Site Area 1. BUILDABLE AREA 2. Subtract 10%of buildable area for stormwater management 3. Subtract 15%of buildable area for streets 4. Equals NET SITE AREA iv. Determine Maximum Dwelling Units 1. NET SITE AREA 2. Multiple by land use classification base density 3. Equals Pre Bonus Maximum Dwelling Units Allowed 3. Density Bonus 57 I. The maximum increase in density shall be limited to twenty(20)percent of the permitted density. The following list of incentives may be utilized to reach a density bonus not to exceed twenty(20)percent. 1. Internal trails and open spaces are connected with existing or potential multi use trails and open space outside of the development and provide access to the public.Open space must be connected to larger greenway systems when technically possible. 3-5% 2. The amount of open space provided exceeds the required open space per section=_^for the development by ten(10)percent or more. 3-5% 3. Open space within the development is placed into a conservation easement with a legally incorporated land conservation organization or donated to a public open space agency. 3-5% 4. Wetland restoration and/or enhancement is performed that is substantially in excess of the U.S.Army Corps of Engineers permit requirements. 3-5% 5. Remnant prairies,savannas,and woodlands are substantially restored prior to the turnover of the property to the Homeowners Association or land conservation organization. Such restoration will consist of the removal of invasive trees,brush,and herbaceous species and the establishment of native herbaceous species. 3-5% 6. Innovative detention/retention basins such as(a)significant use of native vegetation such as prairies and wetlands to retain water,(b)integration of natural land forms,existing soil filtration characteristics,and natural landscaping into the drainage plan,and/or(c)alternatives to detention basins such as stormwater infiltration in naturalized swales, rain gardens,and gently sloped depressional areas. 3-5% B. Open Space Requirements 1. A minimum percentage of land shall be designated as permanent open space dependent upon the United City of Yorkville's Comprehensive Plan land use classification for said property. The open space area shall be including all non-buildable area and a minimum of 20%of the buildable area. Land Use Classification Minimum Open Space based on Base Site Area Rural Neighborhood 60% Estate Neighborhood 50% Suburban Neighborhood 40% 2. Open space must be dedicated or reserved for one or more of the following uses: I. Conservation and protection of areas that potentially pose a significant hazard to people or property(floodplains,wetlands,and lands whose slope and/or soils make them particularly susceptible to subsidence or erosion when disturbed by development activities) II. Conservation and protection of any identified significant natural areas(stream corridors, woodlands,hedge rows,rare plant communities,important wildlife habitats,etc.)or other environmentally sensitive areas where development might threaten water quality or ecosystems; III. Provision of active and/or passive outdoor recreation opportunities including but not limited to,ball fields,playgrounds,tennis courts,swimming pools, basketball courts,golf courses,fishing ponds,shared-use trails,and picnic areas for the use of the general public. Golf courses shall be designed in compatibly with the Audubon Cooperative 58 Sanctuary Program for Golf Courses and shall endeavor to maximize water quality benefits through the following practices:(a)use of reclaimed water, (b)use of native wetland vegetation along ponds,(c)use of landscaping design and plant material that emphasize native species and promote biodiversity,and(d)limited use of pesticides or integrated pest management. iv. Pasture and/or agricultural cropland areas. 3. Ownership and Management I. The petitioner must identify the owner of the open space and is responsible for obtaining and filing an official letter of acceptance of the ownership and maintenance responsibilities. A Property Owners'Association may transfer or convey any and all open space to a land conservation agency or similar entity. ii. The designated owner,or if turned over to a land conservation agency or similar entity, is responsible for maintaining the open space and any associate facilities. If a property owner association is the owner, membership in the association is mandatory and automatic for all property owners of the subdivision and their successors. The petitioner must submit a management plan for the open space and all common areas. The management plan must: 1. Allocate responsibility and guidelines for the maintenance and operation of the open space and any associated facilities,including provisions for ongoing maintenance and for long-term capital improvements; 2. Estimate the costs and staffing requirements needed for maintenance, operation,and insurance and outline the means by which necessary funding will be obtained or provided; 3. Provide that any changes to the management plan be approved by City Staff; 4. Provide for the enforcement of the management plan; 5. A budget must be included which lists operations and capital expenses; 5. Thereafter,yearly inspections will be administered by a qualified consultant selected by and paid for by the property owners'association. A copy of said yearly inspection shall be provided to the City. 4. Legal Instrument for Permanent Protection L The open space must be protected in perpetuity by a binding legal instrument that is recorded with the deed. The legal instrument must be one of the following 1. A permanent conservation easement in favor of either: a. A certified land trust or similar conservation-oriented,non-profit organization with legal authority to accept such easements. b. A governmental entity 2. An open space tract protected by a permanent restrictive covenant for conservation and/or agricultural purposes in favor of a governmental entity;or 3. An equivalent legal tool that provides permanent protection,as approved by the state's attorney. H. The instrument for permanent protection must include clear restrictions on the use of the open space. These restrictions must include all restrictions contained in this section, all restrictions approved by the City Council, and any further restrictions the applicant chooses to place on the open space. C. Development Evaluation Criteria 1. In evaluating the layout,amount,and location of lots and open space,the United City of Yorkville shall evaluate the extent to which the site plan: 59 I. Protects floodplains,wetlands and steep slopes from clearing,grading,filling or construction; H. Preserves and maintains mature woodlands,existing fields,pastures,and prairies; iii. Dwellings sited on least prime agricultural soils iV. Maintains or creates a buffer of native species vegetation of at least 75 feet in depth adjacent to wetlands and surface waters V. designs around existing hedgerows and treelines and minimizes impacts on woodlands, especially those containing many mature trees,significant wildlife habitat,or not degraded by invasive species Vi. Protects wildlife habitats and ravines Vii. Leaves scenic views and vistas unblocked,particularly as seen from public thoroughfares Viii. Avoids siting new construction on prominent hilltops or ridges IX. Includes a pedestrian circulation system designed to assure that pedestrians can walk/bike safely and easily on the site,between properties and activities within the open space system. All footpaths should connect with off-road trails,which in turn should link with potential open space on adjoining undeveloped properties(or with existing open space on adjoining developed properties) X. Provides for contiguous open space. To the greatest extent practicable,open space shall be designed as a single block with logical,straightforward boundaries. 60 SAMPLE LOW IMPACT DEVELOPMENT ORDINANCE 1. Scope This Ordinance sets standards for implementation of Low Impact Development methods which shall be used to meet the requirements of the [list all existing governing agency ordinances here that reference stormwater management regulations] and other subsequent acts that pertain to and are affected by regulations in this Ordinance. II. Purpose and objectives A. Purpose The purpose of this Ordinance is to lessen the impact of development through the reduction of necessary controls for stormwater management, especially those for control and conveyance to a stormwater detention or retention basin, and promote public health, safety, and welfare. B. Objectives Specific objectives include the following: 1. To prevent the necessity for control methods to collect and store stormwater runoff resulting from the development of land. 2. To assure that the volume and rate of stormwater runoff originating from property is not in excess of the pre-existing development hydrology. 3. To protect groundwater, minimize soil erosion, and reduce flooding potential. 4. To conserve the water from the rainfall event. 5. To preserve the existing natural drainage system to minimize the need for the construction of enclosed, underground storm drain systems, or storm sewer systems. 6. To restrict or eliminate stormwater runoff entering and leaving development sites. 7. To prevent unnecessary stripping of vegetation and loss of habitat, soils, ecosystems, or other pre-existing natural systems. S. To eliminate the need for costly maintenance and repairs to roads, embankments, ditches, streams, lakes, wetlands, and stormwater control facilities that are a result of inadequate soil erosion and stormwater runoff control. 9. To discourage the design of stormwater control systems,but use on site stormwater management techniques to prevent flooding,protect water 1 quality; protect wildlife habitat, education, recreation, and wetlands protection. 10. To reduce the detrimental impacts of stormwater flows on downstream communities and ecosystems. III. General Provisions A. Jurisdiction This Ordinance shall apply to all subdivision of land within the incorporate limits of the [governing agency] and within its contiguous territory, but not more than one and one-half miles beyond the incorporated limits of the [governing agency]. B. Interpretation 1. The provisions of this Ordinance shall be held to be the minimum requirements for the promotion of public health, safety, and welfare. 2. Where the conditions imposed by any provision of the Ordinance are either more restrictive or less restrictive than comparable conditions imposed by any other ordinance, law, resolution, rule, or regulation of any kind, the regulations that are more restrictive (or which impose higher standards or requirements) shall govern. 3. This Ordinance is not intended to abrogate any easement, covenant, or any other private agreement, provided that where the regulations of this Ordinance are more restrictive (or impose higher stands or requirements) than such easements, covenants, or other private agreements, the requirements of this Ordinance shall govern. C. Justification 1. The benefits of Low Impact Development include the following: a. Environmental benefits: improved stormwater management, reduced impacts on wetland, streams, and other bodies of water, enhanced water quality (surface and groundwater), better protection of ecological and biological systems, and preservation of open space b. Benefits to municipalities: reduced costs for new or expanded infrastructure and for maintenance of stormwater structures. c. Benefits to developers: cost savings as a result of reduced infrastructure (stormwater structures, streets, curbs, gutters) and less site work including clearing and grading. Increased marketability of lots and projects. 2 IV. Definition of Terms The following terms and phrases shall have the meaning given herein, unless the context otherwise requires: Alley: A public right-of-way, primarily designed to serve as secondary access to the side or rear of properties whose principal frontage is on another street. Building setback line: A line across a lot or parcel of land, establishing the minimum open space to be provided between the line of a building or structure, and the lot line of the lot or parcel. Best Management Practice (BMP): Measure used to control the stormwater runoff and stormwater related effects of development, and includes structural devices to reduce runoff rates and volumes, and protect aquatic habitats. Non-structural approaches used to prevent contamination of runoff through public education, site planning, and easements. Commercial use: All land uses except for single family and duplex (attached) dwelling and appurtenant structures. The use of property in connection with or for the purchase, sale, display, or exchange of good merchandise, or personal services, as well as the maintenance or operation of businesses or recreational or amusement enterprises. Conveyance facility: A surface or subsurface structure or channel which transports stormwater runoff. Cul-de-sac: A street having only one outlet, and an appropriate terminal for the reversal of traffic movement, without the need to back up. Design storm: A rainfall event that has a specific statistical probability of occurring in any given year. Detention basin: A structure or facility, natural or artificial, which stores stormwater on a temporary basis and releases it at a controlled rate. A detention basin is designed to not hold stormwater for over a designated period of time. Development: Any man-made change to real estate, including: b. preparation of a plat of subdivision c. construction, reconstruction, or placement of a building or any addition to a building d. installation of a manufacturer home on a site, preparing a site for a manufactured home, or installing a travel trailer on a site for more than 180 days e. construction of roads, bridges, or similar projects f. redevelopment of a site g. filing, dredging, grading, clearing, excavating, paving, or other non- agricultural alteration of the ground surface 3 h. storage of materials, or deposit of solid or liquid waste i. any other activity that might alter the magnitude, frequency, deviation, direction, or velocity of stormwater flows, from a property Disturbed area: An area of land subjected to erosion due to the remove of vegetative cover and/or earthmoving activities. Drainage system: All facilities, channels, and areas which serve to convey, filter, store, and/or receive stormwater, either on a temporary or permanent basis. Drainage well: A bed of stone constructed for the purpose of trapping stormwater for infiltration into the ground. Enforcing agency: A public agency designated to enforce permit requirements. Environmentally sensitive sites: Sites that have the potential to be damaged by stormwater runoff and result in environmental degradation. Governing body: the agency responsible for enforcement of the ordinance. Lot: a portion of a subdivision or other parcel of land, intended for transfer of ownership, or for building developments Low Impact Development(LID): Approach to site planning, design and development that reduces stormwater impacts. Accomplished through mimicking pre-development hydrology, stormwater is treated as close to the source as possible. Water is treated on a smaller scale. Parking lot: An area permanently reserved and/or used for the temporary storage of motor vehicles Plan, Concept: A tentative map or drawing which indicates the subdivders proposed layout of a subdivision, including a site plan indicating existing offsite roadway connections Plan, Final: The final plat,plus all accompanying information required Plan, Preliminary: The preliminary plat, plus all accompanying information Retention basin: A structure or facility, natural or artificial, which stores stormwater on a temporary basis and releases it at a controlled rate. The body of water has a fixed minimum and maximum water elevation between runoff events. V. Permits required 1. Permits are required in accordance with [list all existing governing agency ordinances here that reference stormwater management regulations]. 4 VI. Exemptions 1. Exemptions must be approved by staff and council. VII. Requirements 1. A preliminary planning meeting shall be held between the developer and the [governing agency] to determine the feasibility of the use of Low Impact Development methods in the design, prior to the submission of a Concept Plan. 2. The Preliminary Plan shall include all possible methods of Low Impact Development incorporated into the plan, and include calculations for reductions in stormwater management requirements. a. The developer shall have defined the project objectives and goals, including the feasibility for water quality, water quantity, peak runoff control, and on-site use of stormwater. b. The project character and aesthetic values shall be clearly defined. 3. All methods proposed shall be approved prior to the approval of the Final Plan. 4. Plan review shall be expedited when Low Impact Development methods are incorporated into the site design to eliminate greater than 50% of the pre- calculated stormwater runoff, for any remaining stormwater requirements, Best Management Practices shall be used. 5. It is the intention of this Ordinance to have 100% of the stormwater be reduced through Low Impact Development methods. VIII. Design and Performance Criteria A. Design Criteria 1. It shall be agreed upon the extent of Low Impact Development methods and the ratio of stormwater management reduction to Low Impact Development improvements to determine the minimum control requirements on a site-by-site basis. 2. Site design feasibility shall include the following analysis: a. Topography b. Maximum drainage area c. Depth to water table d. Soils e. Slopes f. Terrain g. Head h. Location (in proximity to environmentally sensitive features) i. Wildlife habitat 5 3. The goal of the site design feasibility analysis will be to limit the necessity of a collection and conveyance system. 4. A stormwater management plan shall be created detailing how runoff an associated water quality impacts resulting from development shall be controlled or managed, and agreed upon and approved by a licensed professional(s). 5. The use of Low Impact Development methods shall include, but is not limited to the following criteria: a. Alley design b. Bioswales c. Bioretention d. Conservation easements e. Disconnection of downspouts £ Grassed filter strips g. Green roofs h. Lot size reduction i. Permeable pavement (including pavers, concrete and asphalt) j. Rain gardens k. Reduced impervious surfaces 1. Reduced street widths 1n. Reduced sidewalks n. Stormwater management basin reduction or elimination o. Vegetated swales 6. All Low Impact Development methods proposed shall be approved by the (governing agency] prior to the start of work and the issuance of a mass grading permit. 7. A maintenance and management report shall be supplied for the methods incorporated into the development, and the developer or homeowner's association shall be responsible for all improvements. B. Performance Criteria 1. Any area developed using Low Impact Development methods shall be calculated for the imperviousness factor to determine the amount of rainfall a particular site can absorb: a. Precipitation: Design methods shall absorb the first one (I") inch of rainfall that falls during a 24-hour time period. b. Parcel: the total square footage of lot area developed, depending on the intended use(e.g. single family residential, duplex,multi family residential, commercial, supermarkets, stores, planned residential development, etc.) c. Imperviousness factor: represents the amount of average storm water drainage form the average of all parcel zoned for a particular land use. 6 C. Site Design Credits I. Developers are allowed to reduce or eliminate requirements of stormwater management 'Best Management Practices" in exchange for implementation of Low Impact Development methods. 2. Approved incorporated methods of Low Impact Development shall allow for reduced volume of stormwater runoff. 3. Volume is based on the fraction of the total site area or site impervious area affected by the credit. 4. Determine probable credits for the LEED Water Efficiency and Innovative Wastewater Technology goals. Specifically water use, recycling grey water, and water sewage treatment. D. Variations 1. Any variation from the aforementioned methods for Low Impact Development must be approved by the [governing agency. IX. Level and Function of Low Impact Development Methods A. Level One: Distribution 1. Stormwater runoff is distributed using open and vegetated areas to increase infiltration and reduce the amount of stormwater that enter the storm drains. 2. Minimal infrastructural modifications/additions are made. 3. Methods used: a. Sheet flow of water to rain gardens b. Bioswales c. Bioretention cells d. Tree box filters e. Soil amendments f. Structural soil g. Native and sustainable ornamental plants B. Level Two: Hardscape Materials and Curbs 1. Replace hardscape materials with permeable materials. 2. Construct sidewalks, parking bays, and internal alleys with materials, such as permeable concrete or asphalt, to allow water infiltration. 3. Slope roads in the directions of the parking lot islands, and construct curb-less islands to allow water to flow into the island. 4. Minimal infrastructural alterations/additions are required. 5. Methods used: a. Permeable pavers b. Porous concrete c. Porous asphalt 7 d. Curb-less parking lot islands e. Slope water to drain to internal islands f. Ditches g. Curb-less streets C. Level Three: Recycling Rainwater and Runoff 1. Above ground LID devices channel and collect rainwater from roofs. 2. Uses sub-surface facilities to treat and collect runoff from roads and sidewalks. 3. Recycled and stored water is used for irrigation and other non-potable purposes. 4. Devices are integral with the buildings and infrastructure. 5. Significant infrastructural alterations/additions are required. 6. Methods used: a. Disconnect roof downspouts b. Green roofs c. Installation of cisterns d. Installation of rain gardens e. Sub-surface storm water retention facility (below parking) f. Rain barrels IX. Monitoring and Operational Maintenance Requirements A. Annual monitoring reports shall be submitted to the [governing agency] prior to January 31 of each following year for a period of five years including the following criteria: 1. Low Impact Development Methods incorporated into the development design 2. Monitoring report of condition of method(s) implemented 3. Monitoring of rainfall events, including intensity and duration 4. Maintenance cost of each individual method installed 5. If reports are not submitted and the method fails, it shall be assumed that it was due to lack of proper monitoring and maintenance and it shall be required that the Low Impact Development method be re-installed and monitored. CZ Reducing 1 w Costs through Impact Development , Strategies I Practices x- iF i�+� ���►"�.- _ v�k }y .fir �_�r � � � ! ��. Reducing Stormwater Costs through Low Impact Development (LID) Strategies and Practices December 2007 EPA 841-F-07-006 Prepared under Contract No. 68-C-02-108 United States Environmental Protection Agency Nonpoint Source Control Branch (4503T) 1200 Pennsylvania Ave., NW Washington, DC 20460 Available for download at www.eaa.gov/nas/lid CONTENTS Contents............................•----........................................................................................................................i Tables..............................................•--•-•-•---•--•...............................................................................................ii Foreword.............. "' ........................................................................................................................................111 Executive Summary........................................••-•••........................................... ..iv .......................................... Introduction...........................................................................•--•--•-•.........................•••••-•-••............................1 Background................................................................ ........1 LowImpact Development.............................................................................•---••--•••----..........................2 Evaluations of Benefits and Costs ................................................................................................................6 Overviewof Benefits..............................................................................................................................6 Environmental Benefits ...................................................................................................................7 Land Value and Quality of Life Benefits.........................................................................................8 ComplianceIncentives.....................................................................................................................9 CostConsiderations............................................................................................................••-•••..............9 CaseStudies........................................................................................................................................ 2nd Avenue SEA Street, Seattle,Washington......................................................................................12 Auburn Hills Subdivision, Southwestern Wisconsin........................................................................... 13 Bellingham,Washington,Parking Lot Retrofits..................................................................................14 Central Park Commercial Redesigns, Fredericksburg,VA(A Modeling Study)................................. 15 Crown Street,Vancouver,British Columbia........................................................................................15 Gap Creek Subdivision, Sherwood,Arkansas......................................................................................17 Garden Valley, Pierce County,Washington (A Modeling Study)......................................................17 Kensington Estates, Pierce County,Washington (A Modeling Study)................................................18 Laurel Springs Subdivision,Jackson, Wisconsin.................................................................................19 Mill Creek Subdivision, Kane County,Illinois....................................................................................20 Poplar Street Apartments,Aberdeen,North Carolina..........................................................................21 Portland Downspout Disconnection Program,Portland,Oregon.........................................................21 Prairie Crossing Subdivision,Grayslake, Illinois.................................................................................22 Prairie Glen Subdivision,Germantown,Wisconsin.............................................................................23 Somerset Subdivision,Prince George's County,Maryland.................................................................24 Tellabs Corporate Campus,Naperville, Illinois.... ....... ..............25 Toronto Green Roofs,Toronto,Ontario (A Modeling Study) ............................................................26 Conclusion................................................•--••-••-•........................................................................................27 i TABLES Table 1. Summary of LID Practices Employed in the Case Studies...........................................................11 Table 2. Summary of Cost Comparisons Between Conventional and LID Approaches............................12 Table 3. Cost Comparison for 2nd Avenue SEA Street ..............................................................................13 Table 4. Cost Comparison for Auburn Hills Subdivision ..........................................................................14 Table 5. Cost Comparison for Bellingham's Parking Lot Rain Garden Retrofits......................................14 Table 6. Site Information and Cost Additions/Reductions Using LID Versus Traditional Designs...........15 Table 7. Cost Comparison for Gap Creek Subdivision...............................................................................17 Table 8. Cost Comparison for Garden Valley Subdivision.........................................................................18 Table 9. Cost Comparison for Kensington Estates Subdivision................................................................. 18 Table 10. Cost Comparison for Laurel Springs Subdivision...................................................................... 19 Table 11. Cost Comparison for Mill Creek Subdivision.............................................................................20 Table 12. Cost Comparison for Prairie Crossing Subdivision....................................................................22 Table 13. Cost Comparison for Prairie Glen Subdivision...........................................................................23 Table 14. Cost Comparison for Somerset Subdivision...............................................................................24 Table 15. Cost Comparison for Tellabs Corporate Campus.......................................................................25 ii FOREWORD One of the most exciting new trends in water quality management today is the movement by many cities, counties,states,and private-sector developers toward the increased use of Low Impact Development(LID)to help protect and restore water quality. LID comprises a set of approaches and practices that are designed to reduce runoff of water and pollutants from the site at which they are generated.By means of infiltration, evapotranspiration, and reuse of rainwater,LID techniques manage water and water pollutants at the source and thereby prevent or reduce the impact of development on rivers,streams,lakes,coastal waters, and ground water. Although the increase in application of these practices is growing rapidly,data regarding both the effectiveness of these practices and their costs remain limited.This document is focused on the latter issue,and the news is good. In the vast majority of cases,the U.S. Environmental Protection Agency(EPA)has found that implementing well-chosen LID practices saves money for developers,property owners,and communities while protecting and restoring water quality. While this study focuses on the cost reductions and cost savings that are achievable through the use of LID practices,it is also the case that communities can experience many amenities and associated economic benefits that go beyond cost savings.These include enhanced property values,improved habitat, aesthetic amenities, and improved quality of life.This study does not monetize and consider these values in performing the cost calculations,but these economic benefits are real and significant. For that reason, EPA has included a discussion of these economic benefits in this document and provided references for interested readers to learn more about them. Readers interested in increasing their knowledge about LID and Green Infrastructure, which encompasses LID along with other aspects of green development,should see www.epa.gov/nRdesl6Reeninfrastructure and www.eT)a.gov/ni2s/lid./lid. It is EPA's hope that as professionals and citizens continue to become more knowledgeable about the effectiveness and costs of LID, the use of LID practices will continue to increase at a rapid pace. iii EXECUTIVE SUMMARY This report summarizes 17 case studies of developments that include Low Impact Development (LID)practices and concludes that applying LID techniques can reduce project costs and improve environmental performance. In most cases,LID practices were shown to be both fiscally and environmentally beneficial to communities. In a few cases,LID project costs were higher than those for conventional stormwater management practices. However,in the vast majority of cases, significant savings were realized due to reduced costs for site grading and preparation, stormwater infrastructure,site paving,and landscaping. Total capital cost savings ranged from 15 to 80 percent when LID methods were used,with a few exceptions in which LID project costs were higher than conventional stormwater management costs. EPA has identified several additional areas that will require further study. First,in all cases,there were benefits that this study did not monetize and did not factor into the project's bottom line. These benefits include improved aesthetics,expanded recreational opportunities, increased property values due to the desirability of the lots and their proximity to open space,increased total number of units developed,increased marketing potential,and faster sales. Second,more research is also needed to quantify the environmental benefits that can be achieved through the use of LID techniques and the costs that can be avoided. Examples of environmental benefits include reduced runoff volumes and pollutant loadings to downstream waters,and reduced incidences of combined sewer overflows. Finally,more research is needed to monetize the cost reductions that can be achieved through improved environmental performance,reductions in long-term operation and maintenance costs, and/or reductions in the life cycle costs of replacing or rehabilitating infrastructure. iv INTRODUCTION BACKGROUND Most stormwater runoff is the result of the man-made hydrologic modifications that normally accompany development. The addition of impervious surfaces, soil compaction,and tree and vegetation removal result in alterations to the movement of water through the environment.As interception,evapotranspiration,and infiltration are reduced and precipitation is converted to overland flow,these modifications affect not only the characteristics of the developed site but also the watershed in which the development is located. Stormwater has been identified as one of the leading sources of pollution for all waterbody types in the United States. Furthermore,the impacts of stormwater pollution are not static;they usually increase with more development and urbanization. Extensive development in the United States is a relatively recent phenomenon.For the past two decades,the rate of land development across the country has been twice the rate of population growth.Approximately 25 million acres were developed between 19 82 and 1997,resulting in a 34 percent increase in the amount of developed land with only a 15 percent increase in population.1'2 The 25 million acres developed during this 15-year period represent nearly 25 percent of the total amount of developed land in the contiguous states.The U.S.population is expected to increase by 22 percent from 2000 to 2025. If recent development trends continue, an additional 68 million acres of land will be developed during this 25-year period.; Water quality protection strategies are often implemented at three scales: the region or large watershed area,the community or neighborhood,and the site or block. Different stormwater approaches are used at different scales to afford the greatest degree of protection to waterbodies because the influences of pollution are often found at all three scales. For example,decisions about where and how to grow are the first and perhaps most important decisions related to water quality. Growth and development can give a community the resources needed to revitalize a downtown,refurbish a main street,build new schools, and develop vibrant places to live,work, shop, and play. The environmental impacts of development,however,can pose challenges for communities striving to protect their natural resources. Development that uses land efficiently and protects undisturbed natural Iands allows a community to grow and still protect its water resources. Strategies related to these broad growth and development issues are often implemented at the regional or watershed scale. Once municipalities have determined where to grow and where to preserve,various stormwater management techniques are applied at the neighborhood or community level.These measures,such as road width requirements, often transcend specific development sites and can be applied throughout a neighborhood. Finally,site-specific stormwater strategies, such as rain gardens and infiltration areas, are incorporated within a particular development. Of course,some stormwater management strategies can be applied at several scales. For example, opportunities to maximize infiltration can occur at the neighborhood and site levels. 1 Many smart growth approaches can decrease the overall amount of impervious cover associated with a development's footprint.These approaches include directing development to already degraded land;using narrower roads;designing smaller parking lots; integrating retail, commercial, and residential uses; and designing more compact residential lots.These development approaches,combined with other techniques aimed at reducing the impact of development,can offer communities superior stormwater management. Stonnwater management programs have struggled to provide adequate abatement and treatment of stormwater at the current levels of development.Future development will create even greater challenges for maintaining and improving water quality in the nation's waterbodies. The past few decades of stormwater management have resulted in the current convention of control-and-treatment strategies. They are largely engineered, end-of-pipe practices that have been focused on controlling peak flow rate and suspended solids concentrations. Conventional practices,however, fail to address the widespread and cumulative hydrologic modifications within the watershed that increase stormwater volumes and runoff rates and cause excessive erosion and stream channel degradation. Existing practices also fail to adequately treat for other pollutants of concern,such as nutrients,pathogens,and metals. LOW IMPACT DEVELOPMENT Low Impact Development (LID)4 is a stormwater management strategy that has been adopted in many localities across the country in the past several years. It is a stormwater management approach and set of practices that can be used to reduce runoff and pollutant loadings by managing the runoff as close to its source(s) as possible.A set or system of small-scale practices, linked together on the site,is often used.LID approaches can be used to reduce the impacts of development and redevelopment activities on water resources. In the case of new development,LID is typically used to achieve or pursue the goal of maintaining or closely replicating the predevelopment hydrology of the site. In areas where development has already occurred,LID can be used as a retrofit practice to reduce runoff volumes,pollutant loadings,and the overall impacts of existing development on the affected receiving waters. In general,implementing integrated LID practices can result in enhanced environmental performance while at the same time reducing development costs when compared to traditional stormwater management approaches. LID techniques promote the use of natural systems,which can effectively remove nutrients,pathogens,and metals from stormwater.Cost savings are typically seen in reduced infrastructure because the total volume of runoff to be managed is minimized through infiltration and evapotranspiration. By working to mimic the natural water cycle,LID practices protect downstream resources from adverse pollutant and hydrologic impacts that can degrade stream channels and harm aquatic life. It is important to note that typical,real-world LID designs usually incorporate more than one type of practice or technique to provide integrated treatment of runoff from a site. For example,in lieu of a treatment pond serving a new subdivision,planners might incorporate a bioretention area in each yard,disconnect downspouts from driveway surfaces,remove curbs,and install grassed swales in common areas. integrating small 2 practices throughout a site instead of using extended detention wet ponds to control runoff from a subdivision is the basis of the LID approach. When conducting cost analyses of these practices,examples of projects where actual practice-by-practice costs were considered separately were found to be rare because material and labor costs are typically calculated for an entire site rather than for each element within a larger system. Similarly,it is difficult to calculate the economic benefits of individual LID practices on the basis of their effectiveness in reducing runoff volume and rates or in treating pollutants targeted for best management practice(BMP) performance monitoring. The following is a summary of the different categories of LID practices,including a brief description and examples of each type of practice. Consert,ation designs can be used to minimize the generation of runoff by preserving open space. Such Examples of Conservation designs can reduce the amount of impervious surface, Design which can cause increased runoff volumes. Open • Cluster da\-clopn)ent space can also be used to treat the increased runoff • Open space preservation from the built environment through infiltration or • Reduced Pavemcut widths evapotranspiration. For example,developers can use (streets.sidewalks) conservation designs to preserve important features • Shared driveways on the site such as wetland and riparian areas, • Reduced s,:tbacks(shoTtar forested tracts, and areas of porous soils. driveways) Development plans that outline the smallest site • Site fingerprinting during construction disturbance area can minimize the stripping of topsoil and compaction of subsoil that result from grading and equipment use. By preserving natural areas and not clearing and grading the entire site for housing lots,less total runoff is generated on the development parcel. Such simplistic,nonstructural methods can reduce the need to build large structural runoff controls like retention ponds and stormwater conveyance systems and thereby decrease the overall infrastructure costs of the project. Reducing the total area of impervious surface by limiting road widths,parking area, and sidewalks can also reduce the volume of runoff that must be treated. Residential developments that incorporate conservation design principles also can benefit residents and their quality of life due to increased access and proximity to communal open space, a greater sense of community,and expanded recreational opportunities. Infiltration practices are engineered structures or landscape features designed to capture and infiltrate Examples of Infiltration runoff.They can be used to reduce both the volume Practices of runoff discharged from the site and the • Infiltration basins and trenches infrastructure needed to convey,treat,or control • Porous Pawnicut runoff. Infiltration practices can also be used to • Discomiected downspouts recharge ground water.This benefit is especially . Rain gardens and other important in areas where maintaining drinking water Vegetated treatment systerns supplies and stream baseflow is of special concern because of limited precipitation or a high ratio of withdrawal to recharge rates. Infiltration of runoff can also help to maintain stream temperatures because the infiltrated water that moves laterally to replenish stream baseflow typically has a lower temperature than overland flows,which might be subject 3 to solar radiation. Another advantage of infiltration practices is that they can be integrated into landscape features in a site-dispersed manner.This feature can result in aesthetic benefits and,in some cases,recreational opportunities;for example,some infiltration areas can be used as playing fields during dry periods. Runoff storage practices. Impervious surfaces are a Examples of Runoff Storage central part of the built environment,but runoff from Practices such surfaces can be captured and stored for reuse or - Parking tot,street,and sidawalk gradually infiltrated, evaporated,or used to irrigate storage plants. Using runoff storage practices has several - Rain barrels and cisterns benefits.They can reduce the volume of runoff - Dtpressional storage in discharged to surface waters, lower the peak flow lords ape islands and in tree, hydrograph to protect streams from the erosive forces shrub,or turl'depressions of high flows,irrigate landscaping,and provide - Green rows aesthetic benefits such as landscape islands,tree boxes, and rain gardens. Designers can take advantage of the void space beneath paved areas like parking lots and sidewalks to provide additional storage. For example,underground vaults can be used to store runoff in both urban and rural areas. Runoff conveyancepractices. Large storm events can make it difficult to retain all the runoff generated Examples of Runoff on-site by using infiltration and storage practices. In Conveyance Practices these situations,conveyance systems are typically - Eliminating curbs and gutters used to route excess runoff through and off the site. - Creating grassed swales and In LID designs,conveyance systems can be used to grass-lined channels slow flow velocities, lengthen the runoff time of - Roughening surfaces concentration, and delay peak flows that are - Creating long fiow path„over discharged off-site. LID conveyance practices can be landscaped areas used as an alternative to curb-and-gutter systems, and - Installing smaller culverts, pipes,and Inlets from a water quality perspective they have - Creating terraces and check advantages over conventional approaches designed to darns rapidly convey runoff off-site and alleviate on-site flooding. LID conveyance practices often have rough surfaces,which slow runoff and increase evaporation and settling of solids. They are typically permeable and vegetated,which promotes infiltration,filtration, and some biological uptake of pollutants. LID conveyance practices also can perform functions similar to those of conventional curbs,channels, and gutters.For example,they can be used to reduce flooding around structures by routing runoff to landscaped areas for treatment, infiltration,and evapotranspiration. 4 Filtration practices are used to treat runoff by Examples of Filtration filtering it through media that are designed to practices capture pollutants through the processes of physical . Bioretention/rauz aa,dens filtration of solids and/or cation exchange of . Vegctntcd st,•ah:,c dissolved pollutants. Filtration practices offer many • Vegetated filter stripslbutl'crs of the same benefits as infiltration,such as reductions in the volume of runoff transported off- site,ground water recharge,increased stream baseflow,and reductions in thermal impacts to receiving waters. Filtration practices also have the added advantage of providing increased pollutant removal benefits.Although pollutant build-up and removal may be of concern,pollutants are typically captured in the upper soil horizon and can be removed by replacing the topsoil. Lois,impact landscaping. Selection and distribution of plants must be carefully planned when designing a Lands Examples of Law Impact Landscaping functional landscape. Aesthetics are a primary e Planfing native.drought- concern,but it is also important to consider long-term tolerant Plants maintenance goals to reduce inputs of labor,water, . Converting turf areas to shrubs and chemicals. Properly preparing soils and selecting and Imm; species adapted to the microclimates of a site greatly . Reforestation increases the success of plant establishment and . Encomaging linger grass growth, thereby stabilizing soils and allowing for length biological uptake of pollutants. Dense,healthy plant • P1,1ntil,g wildflower mcadows growth offers such benefits as pest resistance ralber than turf along medians (reducing the need for pesticides)and improved soil and in open space infiltration from root growth.Low impact • Amending soil to improve landscaping can thus reduce impervious surfaces, ntfihrahon improve infiltration potential,and improve the aesthetic quality of the site. 5 EVALUATIONS OF BENEFITS AND COSTS To date, the focus of traditional stormwater management programs has been concentrated largely on structural engineering solutions to manage the hydraulic consequences of the increased runoff that results from development. Because of this emphasis,stormwater management has been considered primarily an engineering endeavor. Economic analyses regarding the selection of solutions that are not entirely based on pipes and ponds have not been a significant factor in management decisions.Where costs have been considered,the focus has been primarily on determining capital costs for conventional infrastructure,as well as operation and maintenance costs in dollars per square foot or dollars per pound of pollutant removed. Little attention has been given to the benefits that can be achieved through implementing LID practices. For example,communities rarely attempt to quantify and monetize the pollution prevention benefits and avoided treatment costs that might accrue from the use of conservation designs or LID techniques.To be more specific,the benefits of using LID practices to decrease the need for combined sewer overflow(CSO) storage and conveyance systems should be factored into the economic analyses.One of the major factors preventing LID practices from receiving equal consideration in the design or selection process is the difficulty of monetizing the environmental benefits of these practices. Without good data and relative certainty that these alternatives will work and not increase risk or cost,current standards of practice are difficult to change. This report is an effort to compare the projected or known costs of LID practices with those of conventional development approaches. At this point,monetizing the economic and environmental benefits of LID strategies is much more difficult than monetizing traditional infrastructure costs or changes in property values due to improvements in existing utilities or transportation systems. Systems of practices must be analyzed to determine net performance and monetary benefits based on the capacity of the systems to both treat for pollutants and reduce impacts through pollution prevention. For example, benefits might come in the form of reduced stream channel degradation, avoided stream restoration costs,or reduced drinking water treatment costs. One of the chief impediments to getting useful economic data to promote more widespread use of LID techniques is the lack of a uniform baseline with which to compare the costs and benefits of LID practices against the costs of conventional stormwater treatment and control.Analyzing benefits is further complicated in cases where the environmental performance of the conservation design or LID system exceeds that of the conventional runoff management system,because such benefits are not easily monetized. The discussion below is intended to provide a general discussion of the range of economic benefits that may be provided by LID practices in a range of appropriate circumstances. OVERVIEW OF BENEFITS The following is a brief discussion of some of the actual and assumed benefits of LID practices.Note that environmental and ancillary benefits typically are not measured as part of development projects,nor are they measured as part of pilot or demonstration projects,because they can be difficult to isolate and quantify. Many of the benefits described below are assumed on the basis of limited studies and anecdotal evidence. 6 The following discussion is organized into three categories: (1) environmental benefits, which include reductions in pollutants,protection of downstream water resources,ground water recharge,reductions in pollutant treatment costs,reductions in the frequency and severity of CSOs,and habitat improvements;(2)land value benefits,which include reductions in downstream flooding and property damage,increases in real estate value, increased parcel lot yield,increased aesthetic value,and improvement of quality of life by providing open space for recreation; and(3)compliance incentives. Environmental Benefits Pollution abutenrent. LID practices can reduce both the volume of runoff and the pollutant loadings discharged into receiving waters. LID practices result in pollutant removal through settling, filtration, adsorption,and biological uptake.Reductions in pollutant loadings to receiving waters,in turn, can improve habitat for aquatic and terrestrial wildlife and enhance recreational uses. Reducing pollutant loadings can also decrease stormwater and drinking water treatment costs by decreasing the need for regional stormwater management systems and expansions in drinking water treatment systems. Protection of downstream water resources. The use of LID practices can help to prevent or reduce hydrologic impacts on receiving waters,reduce stream channel degradation from erosion and sedimentation,improve water quality, increase water supply, and enhance the recreational and aesthetic value of our natural resources. LID practices can be used to protect water resources that are downstream in the watershed. Other potential benefits include reduced incidence of illness from contact recreation activities such as swimming and wading,more robust and safer seafood supplies,and reduced medical treatment costs. Ground jmter recharge. LID practices also can be used to infiltrate runoff to recharge ground water. Growing water shortages nationwide increasingly indicate the need for water resource management strategies designed to integrate stormwater,drinking water, and wastewater programs to maximize benefits and minimize costs.Development pressures typically result in increases in the amount of impervious surface and volume of runoff. Infiltration practices can be used to replenish ground water and increase stream baseflow.Adequate baseflow to streams during dry weather is important because low ground water levels can lead to greater fluctuations in stream depth,flows, and temperatures, all of which can be detrimental to aquatic life. Water qualiy,improrementslreduced treatment casts. It is almost always less expensive to keep water clean than it is to clean it up.The Trust for Public Lands noted Atlanta's tree cover has saved more than$883 million by preventing the need for stormwater retention facilities. A study of 27 water suppliers conducted by the Trust for Public Land and the American Water Works Association'found a direct relationship between forest cover in a watershed and water supply treatment costs. In other words,communities with higher percentages of forest cover had lower treatment costs. According to the study, approximately 50 to 55 percent of the variation in treatment costs can be explained by the percentage of forest cover in the source area.The researchers also found that for every 10 percent increase in forest cover in the source area,treatment and chemical costs decreased approximately 20 percent,up to about 60 percent forest cover. 7 Reduced incidence of CSOs. Many municipalities have problems with CSOs,especially in areas with aging infrastructure. Combined sewer systems discharge sanitary wastewater during storm events.LID techniques,by retaining and infiltrating runoff, reduce the frequency and amount of CSO discharges to receiving waters. Past management efforts typically have been concentrated on hard engineering approaches focused on treating the total volume of sanitary waste together with the runoff that is discharged to the combined system. Recently,communities like Portland(Oregon), Chicago,and Detroit have been experimenting with watershed approaches aimed at reducing the total volume of runoff generated that must be handled by the combined system. LID techniques have been the primary method with which they have experimented to reduce runoff. A Hudson Riverkeeper report concluded,based on a detailed technical analysis, that New York City could reduce its LSO's more cost- effectively with LID practices than with conventional,hard infrastructure CSO storage practices. Habitat improrenreuts. Innovative stormwater management techniques like LID or conservation design can be used to improve natural resources and wildlife habitat, maintain or increase land value,or avoid expensive mitigation costs. Land Value and Quality of Life Benefits Reduced downstream flooding and property damage. LID practices can be used to reduce downstream flooding through the reduction of peak flows and the total amount or volume of runoff. Flood prevention reduces property damage and can reduce the initial capital costs and the operation and maintenance costs of stormwater infrastructure. Strategies designed to manage runoff on-site or as close as possible to its point of generation can reduce erosion and sediment transport as well as reduce flooding and downstream erosion. As a result,the costs for cleanups and streambank restoration can be reduced or avoided altogether.The use of LID techniques also can help protect or restore floodplains,which can be used as park space or wildlife habitat.8 Real estate ralue/propeM tar re►�enue. Homeowners and property owners are willing to pay a premium to be located next to or near aesthetically pleasing amenities like water features,open space, and trails. Some stormwater treatment systems can be beneficial to developers because they can serve as a"water"feature or other visual or recreational amenity that can be used to market the property.These designs should be visually attractive and safe for the residents and should be considered an integral part of planning the development. Various LID projects and smart growth studies have shown that people are willing to pay more for clustered homes than conventionally designed subdivisions. Clustered housing with open space appreciated at a higher rate than conventionally designed subdivisions. EPA's Economic Benef is oTRunoff Controls9 describes numerous examples where developers and subsequent homeowners have received premiums for proximity to attractive stormwater management practices. Lot yield. LID practices typically do not require the large,contiguous areas of land that are usually necessary when traditional stormwater controls like ponds are used. In cases where LID practices are incorporated on individual house lots and along roadsides as part of the landscaping,land that would normally be dedicated for a stormwater pond or other large structural control can be developed with additional housing lots. Aesthetic value. LID techniques are usually attractive features because landscaping is an integral part of the designs. Designs that enhance a property's aesthetics using trees, shrubs, and flowering plants that complement other landscaping features can be selected. The use of these designs may increase property values or result in faster sale of the property due to the perceived value of the"extra"landscaping. Public spaces/qualitl,of 1ife/publie participation. Placing water quality practices on individual lots provides opportunities to involve homeowners in stormwater management and enhances public awareness of water quality issues.An American Lives, Inc.,real estate study found that 77.7 percent of potential homeowners rated natural open space as "essential"or"very important"in planned communities.' Compliance Incentives Regulatn►.1,compliance credits. Many states recognize the positive benefits LID techniques offer,such as reduced wetland impacts. As a result,they might offer regulatory compliance credits,streamlined or simpler permit processes, and other incentives similar to those offered for other green practices. For example,in Maryland the volume required for the permanent pool of a wet pond can be reduced if rooftop runoff is infiltrated on-site using LID practices.This procedure allows rooftop area to be subtracted from the total impervious area,thereby reducing the required size of the permanent pool. In addition, a LID project can have less of an environmental impact than a conventional project, thus requiring smaller impact fees. COST CONSIDERATIONS Traditional approaches to stormwater management involve conveying runoff off-site to receiving waters,to a combined sewer system,or to a regional facility that treats runoff from multiple sites.These designs typically include hard infrastructure,such as curbs, gutters,and piping. LID-based designs,in contrast, are designed to use natural drainage features or engineered swales and vegetated contours for runoff conveyance and treatment. In terms of costs,LID techniques like conservation design can reduce the amount of materials needed for paving roads and driveways and for installing curbs and gutters. Conservation designs can be used to reduce the total amount of impervious surface,which results in reduced road and driveway lengths and reduced costs. Other LID techniques,such as grassed swales,can be used to infiltrate roadway runoff and eliminate or reduce the need for curbs and gutters,thereby reducing infrastructure costs. Also,by infiltrating or evaporating runoff,LID techniques can reduce the size and cost of flood-control structures.Note that more research is needed to determine the optimal combination of LID techniques and detention practices for flood control. It must be stated that the use of LID techniques might not always result in lower project costs.The costs might be higher because of the costs of plant material,site preparation, soil amendments,underdrains and connections to municipal stormwater systems, and increased project management. Another factor to consider when comparing costs between traditional and LID designs is the amount of land required to implement a management practice. Land must be set aside for both traditional stormwater management practices and LID practices,but the former require the use of land in addition to individual lots and other community areas,whereas bioretention areas and swales can be incorporated into the landscaping of yards,in rights- 9 of-way along roadsides,and in or adjacent to parking lots. The land that would have been set aside for ponds or wetlands can in many cases be used for additional housing units, yielding greater profits. Differences in maintenance requirements should also be considered when comparing costs. According to a 1999 EPA report,maintenance costs for retention basins and constructed wetlands were estimated at 3 to 6 percent of construction costs,whereas maintenance costs for swales and bioretention practices were estimated to be 5 to 7 percent of construction costs.�1 However,much of the maintenance for bioretention areas and swales can be accomplished as part of routine landscape maintenance and does not require specialized equipment.Wetland and pond maintenance,on the other hand, involves heavy equipment to remove accumulated sediment,oils,trash,and vegetation in forebays and open ponds. Finally,in some circumstances LID practices can offset the costs associated with regulatory requirements for stormwater control. In urban redevelopment projects where land is not likely to be available for large stormwater management practices,developers can employ site-dispersed BMPs in sidewalk areas,in courtyards, on rooftops,in parking lots, and in other small outdoor spaces,thereby avoiding the fees that some municipalities charge when stonnwater mitigation requirements cannot otherwise be met. In addition, stormwater utilities often provide credits for installing runoff management practices such as LID practices.12 10 CASE STUDIES The case studies presented below are not an exhaustive list of LID projects nationwide. These examples were selected on the basis of the quantity and quality of economic data, quantifiable impacts,and types of LID practices used. Economic data are available for many other LID installations,but those installations often cannot be compared with conventional designs because of the unique nature of the design or the pilot status of the project.Table 1 presents a summary of the LID practices employed in each case study. Table 1.Summary of LID Practices Employed in the Case Studies _ LIE]Techni ues I Reduced Biore• Cluster Impervious Permeable Vegetated i Green Name tentiOn Building Area Swale$ Pavement Landscqpiia; Wetlands Ft�aafs 2"d Avenue SEA Street ✓ l ✓ _ Auburn Hills ✓ �f ✓ ✓ V" ✓ Bellingham Parking Lot ✓ Retrofits t Central Park Commercial ✓ ✓ Redesigns Crown Street ✓ ✓ ✓ i J Y Gap Creek ✓ ✓ _1 Garden Valley ✓ ✓ ✓ ✓ ✓ ' l Kensington ✓ ✓ ✓ ✓ ✓ Estates _ Laurel Springs ✓ ✓ ✓ ✓ _ — Mill Creek ✓ ✓ ✓ Poplar Street ✓ ✓ ✓ Apartments Portland Downspout ✓ Disconnection` Prairie Crossing ✓ ✓ ✓ _ ✓ Prairie Glen ✓ ✓ ✓ ✓ ✓ ✓ Somerset ✓ ✓ - Tellabs Corporate ✓ ✓ ✓ ✓ Campus Toronto Green ✓ Roofs *Although impervious area stays the same,the disconnection program reduces directly connected impervious area. The case studies contain an analysis of development costs,which are summarized in Table 2.Note that some case study results do not lend themselves well to a traditional vs. 11 LID cost comparison and therefore are not included in Table 2(as noted). Conventional development cost refers to costs incurred or estimated for a traditional stormwater management approach,whereas LID cost refers to costs incurred or estimated for using LID practices. Cost difference is the difference between the conventional development cost and the LID cost.Percent difference is the cost savings relative to the conventional development cost. Table 2. 'summary of Cost Comparisons Between Conventional and LID Approaches' coliventional Development Cost Parcent Project Cost LID Cost Differenceb DiffereFtcO 2"d Avenue SEA Street $868,803 $651,548 $217,255 25%_ Auburn Hills $2,360,385 $1,598,989 $761,396 �_ 32% Bellingham City Hall $27,600 $5.600 $22,000 80% Bellingham Bloedel Donovan Park _ $52,800 $12,800 $40,000 76% Gap Creek $4,620,600 $3,942,100 $678,500 15% Garden Valley _ $324,400 $26D,700 $63,700 20% Kensington Estates _ $765,700 $1,502,900 -$737,200 -96% Laurel Springs $1,654,021 $1,149,552 $504,469 30% Mill Creeks $12,510 $9,099 $3,411 27% Prairie Glen $1,004,848 $599,536 $405,312 40% Somerset $2,456,843 $1,671,461 $785,382 32% Tellabs Corporate Campus $3,162,160 $2,700,650 $461,510 15% a The Central Park Commercial Redesigns,Crown Street,Poplar Street Apartments,Prairie Crossing,Portland Downspout Disconnection,and Toronto Green Roofs study results do not lend themselves to display in the format of this table. Negative values denote increased cost for the LID design over conventional development costs. `Mill Creek costs are reported on a per-lot basis. 2ND AVENUE SEA STREET, SEATTLE, WASHINGTON 2-Avmue SFA tweet The 2"a Avenue Street Edge Alternative(SEA) Street project was a pilot project undertaken by Seattle Public Utilities to redesign an entire 660-foot block with a number of LID techniques.The goals were to reduce stormwater runoff and to provide a more"livable"community.Throughout the design and construction process, Seattle Public Utilities worked collaboratively with street residents to develop the final street design.13 The design reduced imperviousness, included retrofits of bioswales to treat and manage stormwater, and added 100 evergreen trees and 1,100 shrubs.14 Conventional curbs and gutters were replaced with bioswales in the rights-of-way on both sides of the street,and the street width was reduced from 25 feet to 14 feet.The final constructed design reduced imperviousness by more than 18 percent.An estimate for the final total project cost was $651,548. A significant amount of community outreach was involved,which raised the level of community acceptance. Community input is important for any project,but because this was a pilot study,much more was spent on communication and redesign than what would be spent for a typical project. 12 The costs for the LID retrofit were compared with the estimated costs of a conventional street retrofit(Table 3).Managing stormwater with LID techniques resulted in a cost savings of 29 percent.Also,the reduction in street width and sidewalks reduced paving costs by 49 percent. Table 3. Cost Comparison for 2"d Avenue SEA Street's Conventional Percent of De"eiol-lEnE Percent Total Item goer: 8EA Stket'C r *:. Cost Savings* Savin s* Savin s* Site preparation $65,084 $88,173 -$23,089 -35% -11% Stormwater management $372,988 $264,212 $108,776 29% 50% Site paving and sidewalks $287,646 $147,368 $140,278 49% 65% Landscaping $78,729 $113,034 -$34,305 -44% -16% Misc.(mobilization,etc.) $64,356 $38,761 $25,595 40% 12% Total $868,803 $651,548 $297,255 — -- t Negative values denote increased cost for The LID design over conventional development costs. The avoided cost for stormwater infrastructure and reduced cost for site paving accounted for much of the overall cost savings.The nature of the design,which included extensive use of bioswales and vegetation,contributed to the increased cost for site preparation and landscaping. Several other SEA Street projects have been completed or are under way, and cost evaluations are expected to be favorable. For this site, the environmental performance has been even more significant than the cost savings. Hydrologic monitoring of the project indicates a 99 percent reduction in total potential surface runoff, and runoff has not been recorded at the site since December 2002,a period that included the highest-ever 24-hour recorded rainfall at Seattle-Tacoma Airport."'The site is retaining more than the original design estimate of 0.75 inch of rain. A modeling analysis indicates that if a conventional curb-and-gutter system had been installed along 2"d Avenue instead of the SEA Street design, 98 times more stormwater would have been discharged from the site.T' AUBURN HILLS SUBDIVISION, SOUTHWESTERN WISCONSIN L;8 A Aub urn Hills in southwestern Wisconsin is a um"�t�residential subdivision developed with conservation design principles. Forty percent of the site is preserved as open space;this open space includes wetlands,green space and natural plantings,and walking trails.The subdivision was designed to include open swales and bioretention for stormwater management.To determine potential savings from using conservation design,the site construction costs were compared with the estimated cost of building the site as a conventional subdivision.1s Reduced stormwater management costs accounted for approximately 56 percent of the total cost savings.A cost comparison is provided in Table 4. Other savings not shown in Table 4 were realized as a result of reduced sanitary sewer,water distribution,and utility construction costs. 13 Table 4. Cost Com arison for Auburn Hills Subdivision 19 Conventional Percent of Development Auburn Hills LID Cost Percent Total Item avt -,-) t Savings* Savings* Savin s* Site preparation $699,250 $533,250 $166,000 24% 22% Stormwater management $664,276 $241,497 $422,779 64% 56% Site paving and sidewalks $771,859 $584,242 $187,617 24% 25% Landscaping $225,000 $240,000 415,000 -7% -2% Total $2,360,385 $1,598,989 $761,396 — — *Negative values denote increased cost for the LID design over conventional development costs. The clustered design used in the development protected open space and reduced clearing and grading costs. Costs for paving and sidewalks were also decreased because the cluster design reduced street length and width. Stormwater savings were realized primarily through the use of vegetated swales and bioswales.These LID practices provided stormwater conveyance and treatment and also lowered the cost of conventional stormwater infrastructure.The increase in landscaping costs resulted from additional open space present on-site compared to a conventional design,as well as increased street sweeping. Overall,the subdivision's conservation design retained more natural open space for the benefit and use of the homeowners and aided stormwater management by preserving some of the site's natural hydrology.20 BELLINGHAM,WASHINGTON, PARKING LOT RETROFITS The City of Bellingham,Washington,retrofitted two Z, —,parking lots—one at City Hall and the other at Bloedel Donovan Park--with rain gardens in lieu of installing underground vaults to manage stormwater.31 At City Hall,3 parking spaces out of a total of 60 were used for the rain garden installation.The Bloedel Donovan Park retrofit involved converting to a rain garden a 550- square-foot area near a catch basin. Both installations required excavation,geotextile fabric,drain rock,soil amendments,and native plants. Flows were directed to the rain gardens by curbs. An overflow system was installed to accommodate higher flows during heavy rains. The City compared actual rain garden costs to estimates for conventional underground vaults based on construction costs for similar projects in the area($12.00 per cubic foot of storage).Rain garden costs included labor,vehicle use/rental, and materials. Table 5 shows that the City Hall rain garden saved the City$22,000,or 80 percent,over the underground vault option; the Bloedel Donovan Park installation saved$40,000,or 76 percent. Table 5. Cost Comparison for Bellingham's Parking Lot Rain Garden Retroflts22 Conventional Vault Project Cost Rain Garden Cost Cost Savings Percent Savin s City Hall $27,600 $5,600 $22,000 60% Bloedel Donovan Park $52,800 $12,800 $40,000 76% 14 CENTRAL PARK COMMERCIAL REDESIGNS, FREDERICKSBURG,VA(A MODELING STUDY) + The Friends of the Rappahannock undertook a costD analysis involving the redesign of site plans for several stores in a large commercial development in the Fredericksburg,Virginia,area called Central , Park. Table 6 contains a side-by-side analysis of the cost additions and reductions for each site L for scenarios where LID practices(bioretention areas and swales)were incorporated into the existing,traditional site designs. In five of the six examples,the costs for the LID redesigns were higher than those for the original designs,although they never exceeded$10,000,or 10 percent of the project. One example yielded a$5,694 savings.The fact that these projected costs for LID were comparable to the costs for traditional designs convinced the developer to begin incorporating LID practices into future design projects.25 Table 6.Site Information and Cost Additions/Reductions ilsing LID Versus Traditional Designs Total Impervious Percent of Change in Total BMP Area Treated Impervious Cosa Cost Cost After Name Area W ft2 Area Treated Addle onQ €tedtictionse Redesign Breezewood Station 4,800 64,165 98.4% $36,696 $34,785 +$1,911 Alternative 1 Breezewcod Station 3,500 38,775 59.5% $24,449 $21,060 +$3,389 Alternative 2 Olive Garden 1,780 31,900 59.1% $14,885 $11,065 +$3,790 Kohl's,Best Buy,& 14,400 354,238 56.3% $89,433 $80,380 +$9,053 Office Depot First Virginia Bank 1,310 20,994 97,7% $6,777 $1,148 +$5,629 Chick-Fil-Al 1,326 28,908 82.2% $6,846 $12,540 --$5,694 a Addition a]costs for curb,curb blocks,storm piping,inlets,underdrains,soil,mulch,and vegetation as a result of the redesign. b Reduced cost for curb,storm piping,roof drain piping,and inlets as a result of the redesign. `Cost reduction value includes the cost of a Stormeeptor unit that is not needed as part of the redesign. CROWN STREET,VANCOUVER, BRITISH COLUMBIA 4" In 1995 the Vancouver City Council adopted a 'r - Greenways program that is focused on introducing pedestrian-friendly green space into the City to ` connect trails,environmental areas,and urban space. - ' As a part of this program,the City has adopted 0 strategies to manage stormwater runoff from "u"4 roadways.Two initiatives are discussed here. I The Crown Street redevelopment project, completed in 2005,retrofitted a 1,100-foot block of traditional curb-and-gutter street with a naturalized streetscape modeled after the Seattle SEA Street design. Several LID features were incorporated into the design. The total imperviousness of the street was decreased by reducing the street width from 28 feet to 21 feet with one- 15 way sections of the road narrowed to 10 feet. Roadside swales that use vegetation and structural grass(grass supported by a grid and soil structure that prevents soil compaction and root damage)were installed to collect and treat stormwater through infiltration.26 Modeling predicts that the redesigned street will retain 90 percent of the annual rainfall volume on-site;the remaining 10 percent of runoff will be treated by the system of vegetated swales before discharging.27.28 The City chose to use the LID design because stormwater runoff from Crown Street flows into the last two salmon-bearing creeks in Vancouver.29 Monitoring until 2010 will assess the quality of stormwater runoff and compare it with both the modeling projections and the runoff from a nearby curb-and- gutter street. The cost of construction for the Crown Street redevelopment was $707,000. Of this, $311,000 was attributed to the cost of consultant fees and aesthetic design features,which were included in the project because it was the first of its kind in Vancouver.These added costs would not be a part of future projects.Discounting the extra costs,the $396,000 construction cost is 9 percent higher than the estimated$364,000 conventional curb-and-gutter design cost.30 The City has concluded that retrofitting streets that have an existing conventional stormwater system with naturalized designs will cost marginally more than making curb-and-gutter improvements,but installing naturalized street designs in new developments will be less expensive than installing conventional drainage systems.31.32 One goal of Vancouver's Greenways program is to make transportation corridors more pedestrian-friendly. A method used to achieve this goal is to extend curbs at intersections out into the street to lessen the crossing distance and improve the line of sight for pedestrians.When this initiative began,the City relocated stormwater catch basins that would have been enclosed within the extended curb.Now, at certain intersections, the City uses the new space behind the curb to install"infiltration bulges"to collect and infiltrate roadway runoff.The infiltration bulges are constructed of permeable soils and vegetation. (The City of Portland, Oregon,has installed similar systems, which they call "vegetated curb extensions.")The catch basins are left in place,and any stormwater that does not infiltrate into the soil overflows into the storm drain system.33 The infiltration bulges have resulted in savings for the City.Because the stormwater infiltration bulges are installed in conjunction with planned roadway improvements, the only additional costs associated with the stormwater project are the costs of a steel curb insert to allow stormwater to enter the bulge and additional soil excavation costs.These additional costs are more than offset by the$2,400 to $4,000 cost that would have been required to relocate the catch basins.To date,the City has installed nine infiltration bulges,three of which are maintained by local volunteers as part of a Green Streets program in which local residents adopt city green space." 16 GAP CREEK SUBDIVISION, SHERWOOD, ARKANSAS Gap Creek's original subdivision plan was revised to include LID concepts.The revised design increased open space from the originally planned 1.5 acres to 23.5 acres.Natural drainage areas - were preserved and buffered by greenbelts. Traffic-calming circles were used, allowing the developer to reduce street widths from 36 to 27 feet. In addition,trees were kept close to the curb line.These design techniques allowed the development of 17 additional lots. The lots sold for$3,000 more and cost$4,800 less to develop than comparable conventional Iots. A cost comparison is provided in Table 7. For the entire development, the combination of cost savings and lot premiums resulted in an additional profit to the developer of$2.2 million.13,36 Table 7.Cost Comparison for Cap Creek Subdivision" Total Cost of Gap Creek Conventional Design LID Cost Cost Savings Percent Savin s Savings per Lot $4,620,600 $3,942,100 $678,500 15% $4,800 GARDEN VALLEY, PIERCE COUNTY,WASHINGTON (A MODELING STUDY The Garden Valley subdivision is a 9.7-acre site in Pierce County,Washington.A large wetland on the eastern portion of the site and a 100-foot buffer account for 43 percent of the site area. Designers ' --- `- evaluated a scenario in which roadway widths were reduced and conventional stormwater management practices were replaced with swales,bioretention, and soil amendments.The use of these LID elements would have allowed the cost for stormwater management on the site to be reduced by 72 percent.A cost comparison is provided in Table 8.;8 Other costs expected with the LID design were a$900 initial cost for homeowner education with$170 required annually thereafter.Annual maintenance costs for the LID design(not included above) were expected to be$600 more than those for the conventional design,but a$3,000 annual savings in the stonnwater utility bill was expected to more than offset higher maintenance costs. 17 Table 8. Cost Comparison for Garden Valley Subdivision39 Conventional Garden Valley LID Item Development Cost Cost Cost Savings' Percent Savings* Slormwater management $214,000 $59,800 $154,200 72% Site paving $110,400 $200,900 --$90,500 —82% Total $324,400 $260,700 1 $63,700 1 — *Negative values denote increased cost for the LID design over conventional development costs. The design incorporated the use of narrower roadways coupled with Grasscrete parking along the roadside, which increased the overall site paving costs.However,this added cost was more than offset by the savings realized by employing LID for stormwater management.The LID practices were expected to increase infiltration and reduce stormwater discharge rates,which can improve the health and quality of receiving streams. KENSINGTON ESTATES, PIERCE COUNTY, - WASHINGTON (A MODELING STUDY) l A study was undertaken to evaluate the use of LID techniques at the Kensington Estates subdivision, a proposed 24-acre development consisting of single-family homes on 103 lots. The study assumed that conventional stormwater management practices would be replaced entirely by LID techniques,including reduced imperviousness,soil amendments,and bioretention areas.The design dictated that directly connected impervious areas on-site were to be minimized.Three wetlands and an open space tract would treat stormwater discharging from LID installations. Open space buffers were included in the design.The LID proposal also included rooftop rainwater collection systems on each house.40.41 The proposed LID design reduced effective impervious area from 30 percent in the conventional design to approximately 7 percent, and it was approximately twice as expensive as the traditional design.A cost comparison is provided in Table 9. Table 9.Cost Comparison for Kensington Estates Subdivision` Conventional arts;igton Estate Item Development Cost 1110 Cost Additional Cost Stormwater management $243,400 $925,400 $682,000 Site paving $522,300 $577,500 $55,200 Total $765,700 $1,502,900 $737,200 Although the study assumed that roadways in the LID design would be narrower than those in the conventional design,site paving costs increased because the LID design assumed that Grasscrete parking would be included along the roadside to allow infiltration.The use of Grasscrete increased the overall site paving costs. 18 The avoidance of conventional stormwater infrastructure with the use of LID afforded significant cost savings.The LID measures eliminated the need for a detention pond and made more lots available for development.The significant cost for the rooftop rainwater collection systems was assumed to be offset somewhat by savings on storrwater utility bills.A3 The study also anticipated that the use of LID would reduce stormwater peak flow discharge rates and soil erosion.Furthermore,greater on-site infiltration increases ground water recharge,resulting in increased natural baseflows in streams and a reduction in dry channels. Proposed clustering of buildings would allow wetlands and open space to be preserved and create a more walkable community.The reduced road widths were anticipated to decrease traffic speeds and accident rates. LAUREL SPRINGS SUBDIVISION,JACKSON, WISCONSIN tAUrE l The Laurel Springs subdivision in Jackson, Wisconsin, is a residential subdivision that was developed as a conservation design community. The use of cluster design helped to preserve open space and minimize grading and paving. The use of bioretention and vegetated swales lowered the costs for stormwater management. The costs of using conservation design to develop the subdivision were compared with the estimated cost of developing the site with conventional practices(Table 1 0)4' The total savings realized with conservation design were just over$504,469, or approximately 30 percent of the estimated conventional construction cost. Savings from stormwater management accounted for 60 percent of the total cost savings. Other project savings were realized with reduced sanitary sewer,water distribution, and utility construction costs. Table 10.Cost Cam parh;an for Laurel Springs Subdivision's Conven0unal Percent of Development Laurel Springs Percent Total Item Coat LID Chet Cost Savings Savings Savings Site preparation $441,600 $342,000 _ $99,600 23% 20% Stormwater management $439,956 $136,797 $303,159 69% 60% Site paving and sidewalks $607,465 $515,755 $91,710 15% 18% Landscaping $165,000 $155,000 $10,000 6% 2% Total $1,654,021 $1,149,552 $504,469 — — In addition to preserving open space and reducing the overall amount of clearing and grading,the cluster design also reduced street lengths and widths,thereby lowering costs for paving and sidewalks.Vegetated swales and bioswales largely were used to replace conventional stormwater infrastructure and led to significant savings.Each of these factors helped to contribute to a more hydrologically functional site that reduced the total amount of stormwater volume and managed stormwater through natural processes. 19 MILL CREEK SUBDIVISION, KANE COUNTY, ILLINOIS The Mill Creek subdivision is a 1,500-acre,mixed- use community uilt as a conservation design i Y � hdlll��k development.Approximately 40 percent of the site Iy < � is identified as open space; adjacent land use is mostly agricultural.The subdivision was built . using cluster development. It uses open swales for stormwater conveyance and treatment, and it has a lower percentage of impervious surface than conventional developments.An economic analysis compared the development cost for 40 acres of Mill Creek with the development costs of 30 acres of a conventional development with similar building density and location.46 When compared with the conventional development,the conservation site design techniques used at Mill Creek saved approximately$3,411 per lot.Nearly 70 percent of these savings resulted from reduced costs for stormwater management,and 28 percent of the savings were found in reduced costs for site preparation.A cost comparison is provided in Table 11. Other savings not included in the table were realized with reduced construction costs for sanitary sewers and water distribution. Table 11, Cost Camp i6%on for Mill Creek Subdivision'' Conventional Percent percent of Development Mill Creek Cost Savings Savings Total Item ("t per Lot LID Cast p er Lot per Lot er Lot Savings Site preparation $2,045 $1,086 $959 47% 28% Stormwater management $4,535 $2,204 $2,331 51% 68% Site paving and sidewalks $5,930 $5,809 $129 j 2% j 4% Total $12,510 $9,099 $3,411 1 — I — The use of cluster development and open space preservation on the site decreased site preparation costs. The majority of the cost savings were achieved by avoiding the removal and stockpiling of topsoil. In addition to cost savings from avoided soil disturbance, leaving soils intact also retains the hydrologic function of the soils and aids site stormwater management by reducing runoff volumes and improving water quality. The site's clustered design was also responsible for a decrease in costs for paving and sidewalks because the designers intentionally aimed to decrease total road length and width. The designers used open swales as the primary means for stormwater conveyance. Coupled with other site techniques to reduce runoff volumes and discharge rates, significant savings in stormwater construction were avoided because of reduced storm sewer installation;sump pump connections;trench backfill; and catch basin, inlet,and cleanout installation. In addition to the cost savings,the conservation design at Mill Creek had a positive effect on property values: lots adjacent to walking/biking trails include a$3,000 premium, and lots adjacent to or with views of open space include a$10,000 to$17,500 premium.The 20 600 acres of open space on the site include 127 acres of forest preserve with quality wetlands, 195 acres of public parks,and 15 miles of walking/biking trails."R POPLAR STREET APARTMENTS, ABERDEEN, NORTH CAROLINA The use of bioretention,topographical depressions, grass channels,swales,and stormwater basins at the 270-unit Poplar Street Apartment complex improved stormwater treatment and lowered construction"''` costs.The design allowed almost all conventional vf underground storm drains to be eliminated from the design. The design features created longer flow paths,reduced runoff volume, and filtered pollutants from runoff.According to the U.S.Department of Housing and Urban Development,use of LID techniques resulted in a$175,000 savings(72 percent)40 PORTLAND DOWNSPOUT DISCONNECTION PROGRAM, - PORTLAND, OREGON Puivaftd v The City of Portland,Oregon,implemented a Downspout Disconnection Program as part of its CSO elimination program. Every year,billions of gallons of stormwater mixed with sewage pour into the Willamette River and Columbia Slough through - CSOs. When roof runoff flows into Portland's combined sewer system,it contributes to CSOs. The City has reduced the frequency of CSOs to the Columbia Slough and hopes to eliminate 94 percent of the overflows to the Willamette River by 201 L"' The Downspout Disconnection Program gives homeowners,neighborhood associations, and community groups the chance to work as partners with the Bureau of Environmental Services and the Office of Neighborhood Involvement to help reduce CSOs. Residents of selected neighborhoods disconnect their downspouts from the combined sewer system and allow their roof water to drain to gardens and lawns.Residents can do the work themselves and earn$53 per downspout, or they can have community groups and local contractors disconnect for them. Community groups earn$13 for each downspout they disconnect. (Materials are provided by the City.) More than 44,000 homeowners have disconnected their downspouts,removing more than I billion gallons of stormwater per year from the combined sewer system.The City estimates that removing the 1 billion gallons will result in a$250 million reduction in construction costs for an underground pipe to store CSOs by reducing the capacity needed to handle the flows.The City has spent$8.5 million so far to implement this program and will continue to encourage more homeowners and businesses to disconnect their downspouts to achieve additional CSO and water quality benefits. 21 PRAIRIE CROSSING SUBDIVISION, GRAYSLAKE, ILLINOIS The Prairie Crossing subdivision is a conservation suhd�si�ri development on 678 acres,of which 470 acres is open space.The site was developed as a mixed-use community with 362 residential units and 73 acres of commercial property, along with schools,a community center,biking trails,a lakefront beach, and a farm.The site uses bioretention cells and vegetated swales to manage stormwater.51 A cost analysis was performed to compare the actual construction costs of Prairie Crossing with the estimated costs of a conventional design on the site with the same layout. Cost savings with conservation design were realized primarily in four areas: stormwater management,curb and gutter installation,site paving, and sidewalk installation. The total savings were estimated to be almost$1.4 million,or nearly$4,000 per lot(Table 12). Savings from stormwater management accounted for approximately 15 percent of the total savings.The cost savings shown are relative to the estimated construction cost for the items in a conventional site design based on local codes and standards. Table 12. Cost Comparison for Prairie Crossing Subdivisions` Item Cost Savings Percent Savings Reduced Road Width $178,000 13% Stormwater Management $210,000 15% Decreased Sidewalks $648,000 47% Reduced Curb and Gutter $339,000 25% Total $1,375,000 — Reduced costs for sidewalks accounted for nearly half of the total cost savings. This savings is attributed in part to the use of alternative materials rather than concrete for walkways in some locations. In addition,the design and layout of the site,which retained a very high percentage of open space, contributed to the cost savings realized from reducing paving,the length and number of sidewalks,and curbs and gutters. The use of alternative street edges,vegetated swales,and bioretention and the preservation of natural areas all reduced the need for and cost of conventional stormwater infrastructure." Benefits are associated with the mixed-use aspect of the development as well:residents can easily access schools,commercial areas,recreation, and other amenities with minimal travel. Proximity to these resources can reduce traffic congestion and transportation costs. Also,mixed-use developments can foster a greater sense of community and belonging than other types of development. All of these factors tend to improve quality of life. 22 PRAIRIE GLEN SUBDIVISION, GERMANTOWN, WISCONSIN r +•ra�na Gl�� The Prairie Glen subdivision is nationally recognized for its conservation design approach. A significant portion of the site(59 percent) was ; preserved as open space.Wetlands were constructed to manage stormwater runoff, and the open space4 allowed the reintroduction of native plants and wildlife habitat.The site layout incorporated hiking trails,which were designed to allow the residents to have easy access to natural areas.54 To evaluate the cost benefits of Prairie Glen's design,the actual construction costs were compared with the estimated costs of developing the site conventionally. When compared with conventional design,the conservation design at Prairie Glen resulted in a savings of nearly$600,000. Savings for stormwater management accounted for 25 percent of the total savings.Table 13 provides a cost comparison. Other savings not included in the table were realized with reduced sanitary sewer,water distribution, and utility construction costs. Table 13.Cost Comparison for Prairie Glen Subdivision$5 Conventional Percent of Development Prairie Glen Cost Percent Total Item Cost LID Cost Savings* Savings* Savings* Site preparation $277,043 $188,785 $88,258 32% 22% Stormwater management $215,158 $114,364 $100,794 47% 25% Site paving and sidewalks $462,547 1 $242,707 $219,840 48% 54% Landscaping $50,100 $53,680 -$3,580 -7% --1% Total $1,004,848 1 $599,536 j $405,312 1 — — *Negative values denote increased cost for the LID design over conventional development costs. The cluster design and preservation of a high percentage of open space resulted in a significant reduction in costs for paving and sidewalks.These reduced costs accounted for 54 percent of the cost savings for the overall site.Reduced costs for soil excavation and stockpiling were also realized.The use of open-channel drainage and bioretention minimized the need for conventional stormwater infrastructure and accounted for the bulk of the savings in stormwater management. landscaping costs increased due to the added amount of open space on the site. 23 SOMERSET SUBDIVISION, PRINCE GEORGE'S COUNTY, MARYLAND The Somerset subdivision,outside Washington, ;ia-ner5et D.C.,is an 80-acre site consisting of nearly 200 �lr ���s homes.Approximately half of the development was built using LID techniques;the other half was conventionally built using curb-and-gutter design with detention ponds for stormwater management. Bioretention cells and vegetated swales were used in the LID portion of the site to replace conventional stormwater infrastructure. Sidewalks were also eliminated from the design. To address parking concerns,some compromises were made:because of local transportation department concern that roadside parking would damage the swales,roads were widened by 10 feet.56(Note that there are alternative strategies to avoid increasing impervious surface to accommodate parking, such as installing porous pavement parking lanes next to travel Ianes.) Most of the 0.25-acre lots have a 300-to 400-square-foot bioretention cell, also called a rain garden.The cost to install each cell was approximately$500—$150 for excavation and $350 for plants.The total cost of bioretention cell installation in the LID portion of the site was$100,000 (swale construction was an additional cost).The construction cost for the detention pond in the conventionally designed portion of the site was $400,000, excluding curbs,gutters, and sidewalks.s'ss By eliminating the need for a stormwater pond,six additional lots could be included in the LID design.A comparison of the overall costs for the traditional and LID portions of the site is shown in Table 14. Table 14.Cost Comparison for Somerset Subdivision Conventional Development Somerset Cost LID Cost Cost Savings Percent Savings Savings per Lot $2,456,843 $1,671,461 $785,382 32% $4,000 In terms of environmental performance,the LID portion of the subdivision performed better than the conventional portion.59 A paired watershed study compared the runoff between the two portions of the site, and monitoring indicated that the average annual runoff volume from the LID watershed was approximately 20 percent less than that from the conventional watershed.The number of runoff-producing rain events in the LID watershed also decreased by 20 percent. Concentrations of copper were 36 percent lower; lead,21 percent lower; and zinc,37 percent lower in LID watershed runoff than in conventional watershed runoff.The homeowners' response to the bioretention cells was positive;many perceived the management practices as a free landscaped area. 24 TELLABS CORPORATE CAMPUS, NAPERVILLE, =— – ILLINOIS 1 Tenn, a II The Tellabs corporate campus is a 55-acre site with "Orr-fOe more than 330,000 square feet of office space.After reviewing preliminary planning materials that compared the costs of conventional and conservation design,the company chose to develop the site with conservation design approaches. Because the planning process included estimating costs for the two development approaches,this particular site provides good information on commercial/industrial use of LID."' Development of the site included preserving trees and some of the site's natural features and topography. For stormwater management,the site uses bioswales,as well as other infiltration techniques,in parking lots and other locations.The use of LID techniques for stormwater management accounted for 14 percent of the total cost savings for the project. A cost comparison is provided in Table 15.Other cost savings not shown in Table 15 were realized with reduced construction contingency costs,although design contingency costs were higher. Table 15. Cost Comparison for Tellabs Corporate Campus' Conventional Percent of Development Tellabs Percent Total Item Cost LID Cost Cost Savings Savings Savings Site preparation $2,178,500 $1,966,000 $212,500 10% 46% Stormwater management $480,910 5418,000 $62,910 M 14% Landscape development $502,750 $316,650 $186,100 37% 40% Total $3,962,160 $2,T00,650 $461,510 — — Savings in site preparation and landscaping had the greatest impact on costs. Because natural drainage pathways and topography were maintained to the greatest extent possible,grading and earthwork were minimized; 6 fewer acres were disturbed using the conservation design approach.Landscaping at the site maximized natural areas and restored native prairies and wetland areas.The naturalized landscape eliminated the need for irrigation systems and lowered maintenance costs when compared to turf grass,which requires mowing and regular care. In the end,the conservation approach preserved trees and open space and provided a half acre of wetland mitigation.The bioswales used for stormwater management complemented the naturalized areas and allowed the site to function as a whole; engineered stormwater techniques augmented the benefits of the native areas and wetlands."2 25 TORONTO GREEN ROOFS, TORONTO, ONTARIO (A MODELING STUDY) Toronto is home to more than 100 green roofs.To evaluate the benefits of greatly expanded use of green roofs in the city,a study was conducted using a geographic information system to model the i oraao effects of installing green roofs on all flat roofs aeen Fwfs larger than 3,750 square feet. (The model assumed that each green roof would cover at least 75 percent of the roof area.) If the modeling scenario were implemented, 12,000 acres of green roofs (S percent of the City's land area) would be installed."The study quantified five primary benefits from introducing the green roofs: (1)reduced stormwater flows into the separate stor n sewer system, (2)reduced stormwater flows into the combined sewer system, (3)improved air quality,(4)mitigation of urban heat island effects, and(5) reduced energy consumption.' The study predicted economic benefits of nearly$270 million in municipal capital cost savings and more than$30 million in annual savings. Of the total savings,more than $100 million was attributed to stormwater capital cost savings, $40 million to CS capital cost savings,and nearly$650,000 to CSO annual cost savings.The cost of installing the green roofs would be largely borne by private building owners and developers;the cost to Toronto would consist of the cost of promoting and overseeing the program and would be minimal. Costs for green roof installations in Canada have averaged $6 to$7 per square foot.The smallest green roof included in the study, at 3,750 square feet,would cost between$22,000 and$27,000. The total cost to install 12,000 acres of green roofs would be$3 billion to$3.7 billion.b5'06 Although the modeled total costs exceed the monetized benefits,the costs would be spread across numerous private entities. 26 CONCLUSION The 17 case studies presented in this report show that LID practices can reduce project costs and improve environmental performance. In most cases, the case studies indicate that the use of LID practices can be both fiscally and environmentally beneficial to communities. As with almost all such projects,site-specific factors influence project outcomes,but in general,for projects where open space was preserved and cluster development designs were employed,infrastructure costs were lower. In some cases, initial costs might be higher because of the cost of green roofs, increased site preparation costs,or more expensive landscaping practices and plant species. However,in the vast majority of cases, significant savings were realized during the development and construction phases of the projects due to reduced costs for site grading and preparation, stormwater infrastructure,site paving, and landscaping. Total capital cost savings ranged from 15 to 80 percent when LID methods were used,with a few exceptions in which LID project costs were higher than conventional stormwater management costs. EPA has identified several additional areas that will require further study. First, in all the cases,there were benefits that this study did not monetize and factor into the project's bottom line. These benefits include improved aesthetics,expanded recreational opportunities,increased property values due to the desirability of the lots and their proximity to open space,increased number of total units developed,the value of increased marketing potential, and faster sales. Second,more research is also needed to quantify the environmental benefits that can be achieved through the use of LID techniques and the costs that can be avoided by using these practices. For example,substantial downstream benefits can be realized through the reduction of the peak flows,discharge volumes,and pollutant loadings discharged from the site. Downstream benefits also might include reductions in flooding and channel degradation,costs for water quality improvements,costs of habitat restoration, costs of providing CSO abatement,property damage,drinking water treatment costs, costs of maintaining/dredging navigable waterways, and administrative costs for public outreach and involvement. Finally,additional research is needed monetize the cost reductions that can be achieved through improved environmental performance,reductions in long-term operation and maintenance costs and/or reductions in the life cycle costs of replacing or rehabilitating infrastructure. D.Beach,Coastal Sprawl: The Effects of Urban Design on Aquatic Ecosuctems in the United States(Arlington,VA:Pew Ocean Commission,2002). `USDA,Snmtnary Report: 1997 National Resources Inventory(Washington,DC:U.S. Department of Agriculture,Natural Resources Conservation Service, 1999[revised 2000]). 'Beach,2002. 4 The term LID is one of many used to describe the practices and techniques employed to provide advanced stormwater management;green it frastructtrre,conservation dasign,and sustainable stormwater management are other common terms.However labeled,each of the 27 identified practices seeks to maintain and use vegetation and open space,optimize natural hydrologic processes to reduce stormwater volumes and discharge rates,and use multiple treatment mechanisms to remove a large range of pollutants.In the context of this report,case studies ascribing to one of the above,or similar,labels were evaluated,and these terms are used interchangeably throughout the report. 5 Trust for Public Land, The Economic Benefits qf Open Space(Trust for Public Land, 1999), http://www.tpl.orgitier3 ed.cfm?content item id=l 195&folder id=727(accessed March 29, 2006). 6 Trust for Public Land and American Water Works Association.Protecting the Source(San Francisco,CA:Trust for Public Land,2004). 7 Riverkeeper,Sustainable Raindrops:Cleaning New York Harbor by Greening The Urban Landscape(accessed Nov.30,2007). 8 Trust for Public Land, 1999. 9 USEPA,Economic Benefits of Runoff Controls(Washington,DC:U.S.Environmental Protection Agency,Office of Water, 1995). 10 National Park Service,Economic Impacts ofProtecting Ricers. Trails,and Greennvay Corridors:.4 Resource Book(National Park Service, 1995), htti)://www.nys.gov/Dwro/rtcateconindx.htm(accessed June 1,2006). "USEPA,Preliminary Data Summary of Urban Stonnwater Best Management Practices, EPA-821-R-99-012(Washington,DC: U.S.Environmental Protection Agency, 1999), http://www.eRa.gov/OST/stormwater(accessed March 1,2006). 12 Water Environment Federation,Credits Bring Economic Incentives for Onsite Stormwater Management, Watershed& Wet Weather Technical Bulletin(January 1999). 's C.Kloss and C.Calarusse, GI Report(New York,NY:,Natural Resources Defense Council,April 2006). w R.R.Horner,H.Lim,and S.J.Burges,Hvdrologic Monitoring of the Seattle Ultra-Urban Stormwater Management Projects:Summary of the 2000-2003 Water Years,Water Resources Series:Technical Report No. 181 (Seattle,WA:University of Washington,Department of Civil and Environmental Engineering,2004), http://www.c i.seattl e.wa.0 s/ut i l/stel lent/uoup s/public/(a�snu/(&esb/documents/webeontent/hydrolo gic 200406180904017.pdf.(accessed November 19,2007). '$J.Haugland,Changing Cost Perceptions:An Analysis of Conservation Development (Elmhurst,IL:Conservation Research Institute, 2005), htt ://www.ni e.or /environment/sustainablelcoiiservationdesi cost analysis(accessed March 1,2006). "Horner et al.,2004. 17 Horner et al.,2004. IB Haugland,2005. '9 Haugland,2005. °Haugland,2005. Puget Sound Action Team,Reining in the Rain:A Case Study of the City of'Bellingham's Use of Rain Gardens to Manage Stormwater(Puget Sound Action Team,2004), www.nsat.wa.aov/Publications/Rain Garden book.odf(accessed September 11,2007). 28 "Puget Sound Action Team,2004. `'Friends of the Rappahannock,Example LID Commercial Re-designs and Costs Spreadsheets for Re-designs(Friends of the Rappahannock,2006), http://www.riverfiiends.org/Pub lications/LowIml2ac;tDevelopme It/tabid/86/Default.asax. (accessed November 19,2007). 2'C.S.Ingles,Stafford County Helps Pioneer Low Impact Design Movement, Virginia Town & City 39,no. 8(2004). 25 Ingles,2004. 26 Kloss and Calarusse,2006. A.Steed,Naturalized Streetscapes:A Case Studv of Crown Street, Vancouver(City of Vancouver Greenways,Vancouver,BC:City of Vancouver Greenways,no date), http://w«r«,.su stain abiIitti.ca'Docs/Natui a]ized%20Streetscapes- AS. df?CFID=19075623 CFTOKC.N=60214114(accessed March 31,2006). 'R Personal communication with Otto Kauffmann,Engineering Project Coordinator,City of Vancouver Streets Division,April 2005. `"Scott Deveau,Street in for Crowning Touch, The Vancouver Courier(September 22,2004) hitp://spec.bc.ca/article/article.phl2?articicID=340 (accessed March 9,2005). 10 American dollars converted from Canadian equivalent based on April 25,2005,exchange rate. 31 City of Vancouver,British Columbia,Crown Street: Vancouver's First Enviromnentally Sustainable Street(City of Vancouver,BC,2005),prepared For TAC's Environmental Council, Vancouver,BC,http://www.transportationassociation.ca/english/pdf/conf2005/s5/kauffman.l)df (accessed November 19,2007). 3'Personal communication with Otto Kauffmann,Engineering Project Coordinator,City of Vancouver Streets Division,November 2005. "Kloss and Calarusse,2006. 34 Personal communication with David Yurkovich,Greenways Landscape Designer,City of Vancouver Greenways,April 2005. 35 Haugland,2005. �6 HUD, The Practice of Low Impact Development(LID)(Washington,DC:U.S.Department of Housing and Urban Development,Office of Policy Development and Research,2003), http://www.huduser.org/Public ations/PDF/practLowIMRctDcvel.ndf(accessed March 1,2006). 5'Haugland,2005. 3"CH2MHill,Pierce County Low Impact Development Studv--Final Report(Beileview,WA: CH2MHill,2001),ham:/lwww.co.yierce.w_a.us/xml/services/home/environ/water/CIP/LID/final- lid-report.pdf(accessed March 1,2006). i'CH2MHill,2001. 40 USEPA,Low-Impact Development Pays Off,Nonpoint Source News-Notes 75(May 2005): 7-10,http://www.epa.gov/owow/info/NewsNoteslissue75/75issue.])df(accessed March 1,2006). at C112MHill,2001. ;'CH2MHill,2001. 43 CH2MHill,2001. 29 a"Haugland,2005. 45 Haugland,2005. 46 Haugland,2005. "Haugland,2005. 48 Haugland,2005. a'HUD,2003. 50 Portland Bureau of Environmental Services,Downspout Disconnection Program(Portland, OR:Portland Bureau of Environmental Services,2006), http://www.port landonline.com/bes/index.cfm'?c=31246(accessed March 31,2006). 51 Haugland,2005. 5:Haugland,2005. 51 Haugland,2005. 54 Haugland,2005. 55 Haugland,2005. 5'USEPA,Maryland Developer Grows"Rain Gardens"to Control Residential Runoff, Nonpoint Source News-Notes 42(AugusdSeptember 1995), http://www.ena o v/owow/info/NewsNotesl12df/42issue.pdf (accessed March 1,2006). 5?USEPA,2005. SR HUD,2003. 59 USEPA,2005. Haugland.2005. 61 Haugland,2005. 62 Haugland,2005, 63 D.Banting,H.Doshi,I Li,P.Missios,A.Au,B.A.Curve,and M.Verrati,.Report on the Environmental Benefits and Costs or Green Roof Technology for the City or Toronto(Toronto, ON:City of Toronto and Ontario Centres of Excellence—Earth and Environmental Technologies, 2005),]stty:llwww.tronto.caltereenroofs/pdf/fullreportl03105pdF(accessed December 16,2005). 64 Kloss and Calarusse,2006. 65 American dollars converted from Canadian equivalent based on December 19,2005, exchange rate. 66 Banting et al.,2005. 30 115FTTs LOW IMPACT DEVELOPMENT TOOLKIT Low Impact e elo went on the horizons , J # _ A guide for site planners, engineers., environmental �f consultants, and landscape architects. No matter what the budget, clients expect their consulting teams to manage �I a complex set of engineering and regulatory challenges; stormwater 1 management is an increasingly prominent piece of this puzzle. State standards and EPA's Phase II rules have made stormwater a critical development issue, and many cities and towns are now considering local stormwater bylaws to expand and centralize local authority. However, communities and developers are looking for alternatives to conventional "pipe and pond" stormwater controls, which are often considered unsightly, expensive, and ineffective. Meanwhile, combined sewer overflows are forcing municipalities to address runoff from densely developed areas. There is another way. . Low Impact Development is a set of strategies that treat stormwater management as a site design problem, not an exercise in sizing storm drains and detention ponds. Creative site planning and small, decentralized treatment and infiltration techniques are used to minimize runoff and maintain natural hydrology. Low impact techniques are used nationwide, with an established set of design and performance standards that can be applied to achieve compliance with state and local codes. - •+� Y Increasing interest in low impact strategies has created a growing demand for LID-proficient ........ designers for both new construction and retrofit efforts. a, This publication is one component of the Massachusetts Low Impact Development Toolkit,produced by the Metropolitan Area Planning Council,in coordination with the 1-495 MetroWest Corridor Partnership,and with financial support from United States Environmental Protection Agency. The Massachusetts Low Impact Development Interagency Working Group provided valuable input and feedback on the LID Toolkit. For photo credits,please visit our web site. Principles of Low Impact Development Important LID Techniques Work with the landscape. Low-Impact r t— s l�(7at�wa Identify environmentally sensitive areas and important local features, v � ' then outline a development envelope that .. - a _rna,'vesthat paths; minimize grading and tree clearing, r ' recr�r rundP. y lily Focus on prevention. Minimize runoff by using narrow roadways,smaller parking areas, and Permeable permeable paving on sidewalks and overflow parking areas. Use green Paving rooftops to store and evaporate rainfall before it even leaves the roof. Paving dud}cgs;hat allows rainwater rra Micromanage stormwater. ner-Calale snin the Design the site to create small sub-watersheds and "micromanage" runoff ground close to the source in small decentralized structures. Use a "treatment - train" of multiple techniques to maximize filtration and recharge, }„ Bioretent:ion Vegetated areas tld Keep it simple. " ` c ollec;,treeT,and Before resorting to expensive piped systems, use low-cost approaches and n tnfil'ii_rainwater, Abo nonstructural practices, such as rain gardens, street sweeping, and public v -, -ain knaau t�i °'<•+ .yin t rdc-n education. Send clean roof runoff to vegetated areas for infiltration. Practice multi-tasking. =, = Vegetated Create a multifunctional landscape with stormwater management Swa I es components that provide filtration,treatment, �rjd infiltration. Create �hallow d;aigage features that function as open space, wildlife c'r;anne6 rho t 5Iow habitat, and snow storage area, in addition i �Unoff and filter a to stormwater treatment. Maintain and sustain. •. Cisterns and Teach homeowners and landscaping professionals how to monitor and Rain Barrels maintain rain gardens and swales. Provide public works departments 50_SOAQ gallara with adequate funding levels; educate the public to reduce ollution. tarik.stliat 5wre q g p p .�inurat�r - for landsca ing. Put Low Impact Development to Work Breen Hoofs Research low rmpactprincrples and techniques. Detailed design -�� Veoefd;eii roof manuals for LID techniques and applications are available from public sysrs ,at and nonprofit sources. Many organizations publish case studies of low ''= -_ s, aFs�r rainiaii and impact projects, with sizing details, monitoring data, and cost information 4' ' ``' rturn at to xr Find opportunities to applyLlD techniques Where appropriate, recommend simple low impact techniques such as swales, bioretention cells, or simply disconnecting downspouts from the stormwater system. Educate your clients about LID and the benefits of these techniques. Educate local hoards and regulators While interest in LID is on the rise, many boards and regulators are not familiar with the principles. Provide local officials and board members with information about LID to improve trust and communication during the regulatory review. Team up with experts Some firms in Massachusetts have extensive experience with application of low impact techniques. Find opportunities to partner with them as a learning experience. Help pass a stormwater bylaw. As communities draft stormwater bylaws, it is important that they be structured to permit and encourage Iow impact development. Engineers and other consultants should be involved in this process to ensure that the bylaw is workable and provides predictability for developers. For fact sheets, bylaws, references, and more, visit www.mar)c.org/lid and www.arc-of-innovation.org P&OMEMAO May/June 2005 Low Impact Development: An Alternative Approach to Site Design by Asa Foss Low impact development (LID) is a cost-effective and visually appealing approach to site design that involves innovative land planning practices and technologies for managing stormwater and wastewater. LID techniques are designed to reduce stormwater runoff, protect watersheds, lower installation and infrastructure maintenance costs, and add aesthetic value. The primary goal of this approach is to protect a community's natural, pre- development water flow in order to minimize the ecological Impacts of urbanization. The Partnership for Advancing Technology in Housing (PATH), a public-private initiative dedicated to improving America's housing, outlines LID principles and techniques in The Practice of,Cow Impact Development, developed by the National Association of Home Builders (NAHB) Research Center. This PAS Memo provides background on the development of LID; an overview of the four areas of emphasis; stormwater management, wastewater management, circulation design, and site design; examples of communities that have adopted LID principles; and some of the issues to address when incorporating LID into practice. Background Integrating stormwater controls into site design at the lot level is not a new concept. Ian McHarg promoted this concept 40 years ago In his book Design With Nature and incorporated these principles into many projects, perhaps most famously in The Woodlands in Houston. J. Toby Tourbler and Richard Westmacott, authors of Water Resources Protection Technologies, have also used lot-level stormwater controls extensively in their practices. In the early 1990s planners and ecologists in Prince George's County, Maryland, developed LID formally with support from the U.S. Environmental Protection Agency and the U.S. Department of Defense. LID was originally developed as an alternative to conventional stormwater management approaches, which usually convey untreated stormwater through piping systems into large ponds that are often difficult to maintain. Stormwater runoff is a contentious issue in the Chesapeake Bay watershed, where excess nutrients from lawns and factories flow into creeks and rivers, then drain into the Maryland estuary. In Prince George's County, this approach caused heavily polluted stormwater to contaminate the Chesapeake Bay. Flipping this strategy on its head, county planners sought to control stormwater at the source — on the homeowner or land owner's property — with rain gardens, grassed swales, and other LID techniques. "The philosophy behind LID is that water is not our enemy, it's our friend," says Larry Coffman, former associate director of the programs and planning division in the Prince George's County Department of Environmental Resources. While working for the county, Coffman led the effort to make LID part of the Chesapeake Bay initiative. He and Neil Weinstein, executive director of the Low Impact Development Center, are largely responsible for the county's status as a leading voice in LID. After initial experiments with point-source control of stormwater proved successful, the county expanded Its concept of LID to include all aspects of development that affect water: stormwater management, wastewater treatment, circulation design, and site design. Stormwater Management Four types of environmentally friendly systems are used to control stormwater at its source: infiltration, filtering, conveyance, and collection. Although most of these techniques are less expensive than conventional stormwater management practices, the real value is that they produce a higher quality effluent to recharge groundwater levels. Because each project is unique, planners must undertake a careful site analysis to determine which system is most suitable and how it should be designed. It is important to incorporate LID techniques into a site plan during the design phase of the project. Planners have had notable success in introducing LID concepts at pre-development meetings, which offer owners, developers, and design professionals an opportunity to obtain information from planners about regulations, as well as alternative means of stormwater management that apply to a site-specific development proposal. Infiltration Systems Infiltration systems allow for water absorption into the underlying soil and reduce the amount of runoff and pollutant loads from impervious surfaces. These systems include trenches, drainfields, dry wells, and rain gardens (see figures 1 and 2). Compared with traditional conveyance systems, such as sewers, curbs, and gutters, infiltration systems can be quite cost effective. According to a PATH study, conventional conveyance and collection systems typically cost about $45 per linear foot, while rain gardens cost between $3 and $4 per square foot, plus the cost of plants, which cost approximately $6.40 per cubic foot of stormwater treated, 77— Ilk haF I o Figure 1: Rain Garden In the Somerset a Figure 2: Typical Rain Garden Vegetation Community, Bowie, Maryland Noretentlon areas,or rain gardens, are shallow depressions Vegetation used in rain gardens can be used as plant filled with soil, sand,and plants that naturally retain,filter, material elsewhere on a property as a landscape design and treat stormwater.Often installed adjacent to parking element. lots and In residential settings, rain gardens require regular maintenance,although less time is needed once the garden is established. Source: Asa Foss Source: Asa Foss Filtering Systems While Infiltration systems can remove pollutants from stormwater, filtering systems — including filter strips, dry swales, and wetlands -- are specifically designed for this task. Filter strips and dry swales, or exfiltration trenches, are low-maintenance systems often used for pre-treatment before water enters an infiltration system. Constructed wetlands remove pollutants from stormwater, provide a habitat for wildlife, and often offer recreational and educational opportunities. Conveyance Systems Conveyance systems, which include vegetated channels and grassed swales, carry water to ponds or infiltration systems for treatment. They also slow the erosive velocity of stormwater while filtering pollutants. These systems must have a minimum slope of one degree to avoid standing water. At about 50 cents per square foot, they are less expensive than conventional systems such as curbs or concrete channels. a o Figure 3: Example of a Swale Vegetated swales along a roadway transport starmwater and its pollutants and slow its erosive velocity, while also beautifying the corridor. Source: Seattle Public Utilities Collection Systems Collection systems, typically rain barrels and cisterns, are low-cost water retention devices. Although prices vary by size, rain barrels cost around $100, while cisterns range from $200 to thousands of dollars, depending on size and system complexity. They collect water during storms, which can then be used for Irrigation during dry periods. Rain barrels are stored above ground and capture water from roof downspouts; cisterns, usually much larger, are buried underground. Both storage devices are sealed for mosquito control. Circulation Design New designs for streets, sidewalks, and driveways can maintain traffic circulation while reducing the amount of impervious surfaces. Minimizing the amount of asphalt and other impervious road surfaces decreases the amount of runoff and pollutants, while reducing both infrastructure and maintenance costs. Street and intersection widths, cul-de-sacs, parking, driveways, traffic calming measures, and even street layouts can all be modified to reduce the amount of impervious surfaces. Compared with conventional street layouts, LID roadways have lower maintenance costs, can increase safety through traffic calming measures, and improve a community's appearance through roadway greening. New street designs can also affect the layout of lots, which could increase the volume of open space, connect greenways, and protect sensitive natural features. Street Design Depending on the density, location, and type of development, alternative street networks can often minimize the amount of impervious surfaces, conserve open space, and protect natural features and water quality. A hybrid street network that combines a conventional grid with a curvilinear system combines green space for forests, wetlands, and trees with street elements. This approach reduces the amount of total roadways while still allowing for smooth traffic circulation (see Figures 4 to 5). o Figure 4: Typical Grid Layout o Figure 5: Typical Curvilinear Layout The typical grid layout,which often Includes alleys as The typical curvilinear layout, with cul-de-sacs, often results shown,supports traffic circulation. in less paved area. Source: Low Impact Development: Technical Source: Low Impact Development: Technical Guidance Manual for Puget Sound, 2005. Guidance Manual for Puget Sound, 2005. J~ T (}I �iTiTF'i n Figure 6: Hybrid Street Layout The hybrid street combines the clrculatlon advantages of a grid with the open space aspects of a curvilinear system. Source: Low Impact Development:: Technical Guidance Manual for Puget Sound, 2005, The Puget Sound Action Team, a government partnership charged with developing conservation programs to protect Washington State's Puget Sound, recommends several ways to reduce the length and amount of roadways: • Lengthen street blocks to reduce the number of cross streets for grid or modified grid layouts. • Provide pedestrian paths to connect the end of a cul-de-sac with other pathways, roads, or open spaces. • Create pedestrian routes to neighborhood destinations that are direct, safe, and aesthetically pleasing. • Narrow lot Frontages and cluster homes to reduce the need for more roads. In addition, by reducing paved residential streets to 22 feet wide rather than the conventional 36 feet, ample room can remain for parking on one side of the street and the passage of large vehicles, such as buses and emergency vehicles on the other. This measure can drastically reduce the amount of stormwater runoff and result in substantial cost savings — more than $12,000 per 100 feet of street, according to PATH estimates. Other street design techniques include replacing conventional intersections with traffic circles around rain gardens. This technique safely slows traffic, reduces runoff, and provides aesthetic benefits. A rain garden can also be added to a cul-de-sac to achieve similar results. Parking Reducing the amount of space for parking — especially in suburban areas where garages and driveways typically offer more parking than needed — can have a significant impact on reducing the amount of stormwater runoff. The land saved provides space for larger yards or increased open space. Where parking is necessary, permeable surfaces such as porous asphalt and concrete, gravel, or grass allow stormwater to be absorbed. Site Design As mentioned, modifying a project's lot layout can reduce the length and number of streets needed. LID projects use clustering and other strategies to minimize site disturbance, reduce the amount of impervious surfaces, and permanently set aside open space. A variety of lot layouts can be used to achieve these objectives, including flag lot, zero-lot-line lot, z-lot or z-angled lot, and zipper lot designs (see figure 7). Please note the following caveats when considering these approaches, and check with local regulations to determine whether such lot configurations are allowed: • A flag lot does not meet minimum road frontage requirements. However In some cases houses can be built behind another house with a shared driveway to the street. • Zero-lot-line lots have homes built on the edge of a property. These lots allow for a maximum amount of usable space and are often used in communities that incorporate passive solar into house designs. • Z- or angled z-lots are also placed on lot lines, but they are angled at 30 or 40 degrees, allowing for the use of shared driveways. • A zipper lot concentrates the usable space on the side of the lot by varying the rear yard depth while setting the minimum rear setback to zero. T o Figure 7 Examples of Altemative Lot Layouts Source: The Practice of Low Impact Development, 2003. Wastewater Treatment According to the U.S. Census Bureau, 25 percent of all residential septic systems fail, allowing pathogens, nitrogen, and phosphorous to enter into groundwater. LID techniques can serve as a backup for septic systems to minimize the pollution of groundwater. These techniques Include sand filters, mounds, trickling filters, and aerobic systems. • Sand filters allow the effluent to undergo natural chemical and microbial treatments that purify the water as it percolates through the filter. • Mounds containing a sand filter are typically one to four feet high, and are used in areas with a high water table. • Trickling filters trickle water over a fixed medium, such as rocks, which allows a bed of microorganisms to remove the nitrogen from the wastewater • Aerobic systems are similar to septic systems but allow oxygen to enter, which causes the effluent to deteriorate more rapidly. Urban and Suburban Applications Although LID techniques can be used in many projects, some areas will see greater benefits than others. In suburban developments, opportunities abound to preserve undeveloped spaces and connect them to existing greenways. Because suburbs often require a greater number of roads, stormwater drains, and sewers per capita than cities, reducing or eliminating this infrastructure can result in financial benefits for both installation and maintenance, such as by changing the width and layout of roads or eliminating curb and gutter systems. Because of their size, large suburban developments offer economies of scale, says Neil Weinstein of LIDC. LID is also compelling in urban areas, but usually on a smaller scale. Because stormwater infrastructure is already in place, LID is often used in combination with conventional practices. LID techniques can beautify a city, reduce heat island effects, and reduce the amount of stomwater runoff, lessening the strain on urban infrastructure. Among the techniques that can be used include green roofs and rain gardens. LID in Practice With a foothold in the Northwest and Mid-Atlantic states, support from multiple government agencies, and promotion from the home building industry through the NAHB Research Center, LID has gained acceptance nationwide in both suburbs and cities over the last decade. "Currently, there are hundreds of local governments that promote or allow LID techniques," says Weinstein. Three communities that use LID are described below. A short list of other communities that have adopted LID principles are included in a sidebar at the end of this article. Somerset, Maryland Somerset, an 80-acre, 199-home community developed in 1995 in Prince George's County, Maryland, was the first community to integrate stormwater controls into lot-level site design under the tenets of LID. "We disconnected impervious surfaces and explored the technical and practical aspects of using rain gardens on site. We also reduced the amount of[conventional] conveyance systems and got rid of the ecologically destructive stormwater infrastructure," recalls Larry Coffman. These and other LID techniques saved developers more than $900,000. Rain gardens in Somerset range in size from 300 to 400 square feet, with one or two rain gardens per lot. By combining the gardens with shallow grassed swales next to the streets, the community eliminated the use of curbs, gutters, and even a stormwater pond. Along with decreasing the large "first flush" pollutant carried by stormwater, these techniques saved $4,000 per lot and allowed six additional lots to be developed. Somerset was successfully marketed as an environmentally sensitive development, attracting buyers who were excited to live in a "green" community. The community also has more plants, trees, and green spaces than conventional communities, which has shown to have a beneficial effect on property values. "Experience has shown in every case we know of that has used LID techniques, property values have increased compared to other types of development," notes Coffman. A key to the success of Somerset was educating homeowners about the importance of their cooperation and the impact of garden maintenance on the Chesapeake Bay's water quality. Such outreach was especially important because the community, rather than the municipality, is responsible for the maintenance. To determine what to preserve, the residents "define the ecological underpinnings of the community," says Jeff Schoenbauer, Executive Vice President of the planning firm Brauer &Associates, Ltd., in Hopkins, Minnesota. In the long run, taking action like this at the outset ensures much greater success. "The outreach allows [us] to determine which LID improvements the community will support and potentially maintain," says Weinstein. From these priorities, planners can take a conservation-based approach to site design, identifying the green spaces and then the areas for the built environment. Stafford County, Virginia It took four years for an advocacy group to convince Stafford County to accept LID techniques for stormwater management. The result of this long-term effort is one of the most progressive stormwater management programs in the country, in which every new development must prioritize LID measures. "The process started In 1999 with demonstration projects, then a variety of consensus building efforts, and then education with government staff and elected officials," recalls John Tippett, executive director of Friends of the Rappahannock, a nonprofit organization that seeks to protect water quality through environmentally responsible planning. "Then it advanced to the engineers, who wrestled with some of the more difficult challenges that tend to be roadblocks to LID," such as which techniques and materials to use in which locations. LID supporters educated subcommittees of the planning commission, then moved up to the planning commission, and Finally the Board of Supervisors. Eventually, the county adopted the national Low Impact Development Design strategies manual, a document created by Prince George's County. Tippett regards this manual as the "bible" of LID; many other counties use either this manual or other guides produced by the Low Impact Development Center. "In 2003, a four-year advocacy process culminated in some code changes to facilitate LID in Stafford County," says Tippett. "A year later, those code enhancements took LID from an incentivized option to a requirement that developers do everything practicable. Since the judgment of what is practicable is left up to county staff, the county is working on coming up with some tighter guidelines." "The Stafford County case is a great example of the public and private sectors working together toward a common goal," says Rich Dooley, AICP, of the NAHB Research Center. "Developers nationwide are often interested in using LID techniques In their projects, but they quickly become turned off by the increased time delays, e.g., additional public hearings [and] increased permit review time imposed on them for trying to do something good for the environment. Planners have the chance to play a key role In creating the flexibility needed in the land development regulations to facilitate the use of LID." Seattle Street Edge Alternative (SEA) Streets Seattle's public utilities and transportation departments are experimenting with LID design elements in their Street Edge Alternatives(SEA) projects. By modifying circulation design, SEA Streets significantly Improved stormwater management: the initial project to retrofit a 660-foot long residential street has resulted in a 98 percent reduction in stormwater runoff over the past three years. The project was initiated to control heavily polluted stormwater that ran off impervious road surfaces, adversely affecting the area's creeks and wildlife. To minimize these impacts, more than 100 evergreen trees and 1,100 shrubs were planted, the road width was reduced from more than 20 feet (plus space for angled parking) to 14 feet, and grassed swales and two feet of grass shoulder were added next to the curb-free roads. The amount of parking was determined by each owner, and parallel and angle parking was grouped between swales and driveways. Sidewalks were installed on only one side of the road, which was considered adequate for residential communities (see figures 8 to 10). a Z n • Figure 8 Figure 9 SEA Street Before Redesign SEA Street After Redesign Source: Seattle Public Utilities Source: Seattle Public Utilities E] Figure 10 Aerial View of SEA Street Source: Seattle Public Utilities The pilot project cost$850,000, which included an extensive budget for design and consulting with residents. However, SEA Streets planners anticipate future projects will cost substantially less — and even less than traditional street improvements. "You could take $200,000 off the price just from what we didn't know," says Denise Andrews, manager of Seattle's surface water program. "The pilot phases that we are currently in are more expensive, but as the project becomes institutionalized, all the costs will come down. Even still, these projects are less expensive than standard projects." In addition to the stormwater benefits, the SEA Street had some unanticipated quality-of-life benefits as well. "When you make a street as user- and pedestrian-friendly as we have done, especially in residential areas, people notice," says Andrews. "More and more people get to know their neighbors because they walk more. Now people from other communities are walking down these streets too." Challenges Although there are numerous benefits to LID, it is not without its challenges. Maintenance, site plan modifications, and existing regulations can all be implementation barriers. Maintenance Shifting responsibility for maintaining LID technologies From the municipality to the property owner is one of LID's greatest strengths. It is also a point of contention for LID critics, who often argue that LID imposes a maintenance burden on property owners, and owners may fail to maintain the systems. "The misperception is that LID techniques are difficult to maintain and will fail If they aren't. But most of these techniques really require minimal to no maintenance, and still function very well if they aren't maintained," Weinstein notes. Many LID practices, particularly those relating to circulation and design, require no further effort once they are installed. Other techniques like rain gardens require some maintenance but with proper landscaping such maintenance should be minimal. Site Plan Modifications Incorporating LID into a site plan for the first time can be somewhat complex, because numerous LID techniques are available, and site planners must pick the right ones for each project. Tailoring solutions to the site can be time consuming for the uninitiated. However, as LID techniques are used in similar sites throughout a community, they can usually be replicated for a particular area. The site plan review process also adds a step. Many municipalities, such as Stafford County, require a stormwater concept plan that shows how the project is going to address LID on the site at the earliest stages of the project. Local officials must ensure that this step does not significantly slow the review process, which could erode support for LID. "In Stafford County, the plan doesn't address specifics, but It does provide a broad concept as to how developers are going to use LID techniques." If LID Is not considered to be appropriate for a site, there is flexibility in the code to use other techniques. Existing Regulations Restrictive local ordinances have also inhibited the widespread use of LID. For example, many jurisdictions have road design requirements that mandate excessive amounts of Impervious surfaces. This includes unnecessarily wide roads, as well as larger than necessary road turnarounds and intersections. Many also require the use of conventional drainage systems. By mandating curbs, guttersr and storm drains, they leave no room for LID. "In Southern California, builders have run against some well-meaning public officials that are trying to incorporate LID in ways that are redundant with what's already there" says Dooley. "For example, developers have noted they are required to install a natural swale alongside a curb and gutter."To optimize the benefits of LID, planning departments should consider promoting zoning options that allow for new development techniques. Integrating LID into a Community Using LID may require a change of local ordinances; however, many codes allow LID but may not promote it explicitly. To determine whether ordinances need to be changed, the Low Impact Development Center encourages planners to start by analyzing which LID techniques are currently allowed by code. For example, requirements for water quality control devices and easements may encourage or discourage the use of LID, Once it has been determined how LID fits into the local ordinances, examine whether the techniques can be applied seamlessly. If LID techniques are not prohibited but not commonly used, suggest that developers submit an alternative proposal that uses LID techniques. This proposal c ould be included with the site plan application and considered in conjunction with the site plan review. To determine whether a community's regulations are ready for LID, Dooley recommends asking two questions: Will a developer with a proposal that incorporates LID techniques require more review meetings or public hearings? Is there a need to educate code enforcement officials or planning board members on the LID approach? If the answer to either question is yes, "identify the potential hurdles for integrating LID into the existing regulations — for example, a mandate for curb and gutter," says Dooley. "Then determine the most efficient way that LID can be integrated into the codes." Several counties, such as Stafford County, have successfully taken such steps. If local codes already allow for LID techniques, start educating elected planning board officials. Dooley recommends explaining the principles behind LID and how it helps the community. "Tying the community's mission statement elements back to LID techniques on a one-to-one basis can be really effective," he says. "Since LID uses hundreds of techniques (conservation, minimization, strategic timing, integrated management practices, and pollution prevention), there really isn't any limit to where and how to use LID technology," says Neil Coffman. "You simply pick the suite of LID techniques that best meets your goals given the unique characteristics of the watershed you are working in. The only limitations to LID are one's knowledge, experience, and imagination on integrating ecological functions into the built environment." During 2005, PATH is gathering and publishing more information on LID techniques. One effort will be a major expansion of LID-related information on ToolBase Services, which provides technical information on innovative home building technologies. PATH is interested in hearing from planners who have experimented with LID techniques. To share your story, please contact PATH at info @pathnet.org. Author Asa Foss is an associate with D&R International, an environmental consulting firm that works in support of PATH. Questions about this article may be directed to him at afoss @drintl.com. Resources • The Practice of Low Impact Development • Low Impact Development: Technical Guidance Manual for Puget Sound • Low-Impact Development Design Strategies:An Integrated Design Approach • Onsite Wastewater Treatment Systems Manual • Better Site Design:A Handbook for Changing Development Rules in Your Community • The Storm Water Manager's Resource Center • Non-Residential Low Impact Development Tools • Low Impact Development Center • National do-51te Demonstration Program • Green Roofs for Healthy Cities National Center for Residential Land Development Technologies The NAHB Research Center has recently formed the National Centerfor Residential Land Development Technologies. The center's overarching mission is to focus attention on land development technologies and strategies that consider all aspects of environmental performance and sustainability, and promote the affordability and quality of American housing. LID in Practice Following is a sampling of communities or initiatives that have incorporated LID techniques: Arkansas Gap Creek Subdivision, Sherwood California California Department of Transportation Storm Water Management Program 111inois Prairie Crossing, Grayslake Maryland Somerset Community, Prince George's County Northridge Community, Bowie Minnesota Fox Den, Lino Lakes Bassett Creek Watershed, Minneapolis Oregon Buckman Heights, Portland Utah Little Bear River Watershed, Blacksmith Virginia Tinner Hill Cultural Center, Falls Church Duke Street Square, Alexandria Chancery on the Lake, Alexandria Washington, D.C. Capitol Hill Police Station Retrofit Naval Yards Washington Kensington Estates, Pierce County Salishan Neighborhood Revitalization, Tacoma SEA Streets, Seattle ©Copyright 2005 American Planning Association All Rights Reserved References 1. Center for Neighborhood Technology(CNT). "Stormwater Management and Green Infrastructure". Pamphlet. 2007. www.cnt.or 2. Center of Neighborhood Technology(CNT). The Green Values Calculator. www,greenvalues.cnt.or 3. Metropolitan Area Planning Council, of Boston, Massachusetts. Massachusetts Low Impact Development Toolkit. www.niass.gov/envir/smarter toolkit/pages/mod- lid.html 4. North Carolina State University published by North Carolina Cooperative Extension. "North Carolina Low Impact Development: A Guidebook for North Carolina." June 2009. www.ces.ncsu.cdu/depts/agecon/WECO/lid/documents/NC_LID_Guidebook.pdf. 5. The Northeastern Illinois Planning Council. "The Economics of Low Impact Development." October 2008. www.econw.com/reports/2008_ECONorthwest_NEMO_Low-Imaact-Development.ndf. O:\Committees\Zoning Ordinance Revision\Zoning Comm ission\Meetings\ZC packet 5-26- 10\References.doc