Water: Green Infrastructure
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Water InfrastructureGreen InfrastructureHow Can I Overcome the Barriers to Green Infrastructure?
Water InfrastructureGreen InfrastructureHow Can I Overcome the Barriers to Green Infrastructure?How Can I Overcome the Barriers to Green Infrastructure?
As planners, researchers, and engineers become more aware of the many benefits of green infrastructure, interest is growing in adding sustainable green practices to existing gray systems. Many communities have adopted performance standards or incentives promoting green infrastructure and many more have built demonstration projects but single-purpose gray systems remain the norm.
Barriers to green infrastructure arise throughout the development process – from the design of green infrastructure systems to their permitting and installation – but these barriers are increasingly well understood. Here we identify the barriers that confront municipalities, developers, and engineers in adopting green infrastructure approaches and suggest some strategies to overcome them.
Barriers to green infrastructure arise throughout the development process – from the design of green infrastructure systems to their permitting and installation – but these barriers are increasingly well understood. Here we identify the barriers that confront municipalities, developers, and engineers in adopting green infrastructure approaches and suggest some strategies to overcome them.
Local governments are in the best position to promote sustainable stormwater management on a larger scale, but they also face some of the most complex challenges. Resources are limited, responsibilities are fragmented, and the tolerance for risk is generally low. Fortunately, many strategies exist to overcome these barriers.
Perception that Performance is Unknown
Green infrastructure is often perceived as an emerging technology with a limited track record. Many local governments are therefore skeptical of its performance and prefer to rely on familiar pipe-and-pond approaches. Municipalities may also perceive green infrastructure as untested in their particular location, with their particular soils and climate.
Learn about national and local experience: Researchers and engineers have gathered extensive data on the volume reduction and pollutant removal performance of green infrastructure practices (see Performance Research), and several cities with an exceptional commitment to water resource protection have at least 10 years of experience with green infrastructure (see Library). Several inventories and collections of case studies are also available to find green infrastructure practices near you, including the NEMO LID Atlas
, the Landscape Performance Series
Recognize the multiple benefits of green infrastructure: Municipal officials should also take into account the many benefits (see Benefits) provided by green infrastructure. When all of the water quality, air quality, energy, habitat, and community benefits provided by green infrastructure are taken into account, green infrastructure is often shown to perform much better than single-purpose gray approaches.
Learn about design variations: Green infrastructure approaches are extremely flexible and may be adapted to a range of climate regimes and soil characteristics. Design strategies are discussed below.
Develop pilot programs: Municipalities can gain experience and comfort with green infrastructure approaches by developing pilot programs that test the feasibility of different practices in different locations. Chicago’s renowned Green Alley program, for example, began as a pilot program in 2006.
Perception of Higher Costs
Many municipalities are reluctant to integrate green infrastructure into their capital projects or policies because they suspect that green infrastructure will cost more in the short or long term. In the short term, many municipalities express concern that design and construction costs will be higher for innovative approaches than for a conventional pipe-and-pond approach. In the long term, many municipalities express concern that maintenance requirements and costs are unknown.
Learn about national and local experience: A growing body of experience demonstrates the potential for green infrastructure approaches to improve the triple bottom line for both developers and municipalities. Consult these Cost-Benefit Resources to read about examples from across the country.
Recognize avoided costs: When the avoided costs of stormwater ponds, pipes, paving, clearing, and grading are taken into account, green infrastructure is often as cost-effective as (if not more cost-effective than) conventional approaches to stormwater management. These Cost Analyses quantify many of the avoided costs associated with green infrastructure.
Recognize multiple benefits: Green infrastructure provides many environmental, social, and public health benefits that centralized storage and detention facilities do not. By investing in green infrastructure, municipalities can leverage limited public funds to provide multiple benefits – including not only cleaner water, but cleaner air, higher property values, and more recreational opportunities. A growing number of municipalities have conducted comprehensive Cost Benefit Analyses demonstrating the potential for green infrastructure to provide more value than gray.
Perception of Resistance within Regulatory Community
Some municipalities view the regulatory and enforcement community as unwilling to accept green infrastructure solutions to water quality impairments.
Learn about EPA support of green infrastructure: EPA has developed a series of policy memos reaffirming its support for the integration of green infrastructure into stormwater permits and CSO consent decrees. EPA is committed to working with any communities that are interested in adopting green infrastructure solutions.
Perception of Conflict with Principles of Smart Growth
“Smart Growth” aims to create more vibrant and sustainable communities by concentrating growth in existing cities and suburbs, and by promoting compact built environments with a mix of housing, transportation, and employment choices. Some advocates of smart growth believe that managing stormwater at its source will require large areas of open land and will therefore inhibit compact development. Other advocates of smart growth believe that requiring developers to manage stormwater at its source will disproportionately affect redevelopment costs and inhibit redevelopment.
Learn about the many forms of green infrastructure: The many forms of green infrastructure include several practices that are easily integrated into compact site designs. Some practices, such as planter boxes and rainwater cisterns, can be designed to fit into small spaces. Other practices can be integrated into landscaped or paved areas without requiring additional space. Rain gardens or swales can be placed in medians or parking strips, while permeable pavement can be placed in parking lots, streets, and walkways.
Assess the economic factors that affect developers’ decisions: In 2011, ECONorthwest published a report (PDF) (30 pp, 290K, About PDF)
Perception of Conflict with Water Rights Law
In many Western states, water is such a limited resource that states have developed complex legal systems to define water rights. Each state has different laws and policies. As green infrastructure practices become more common, these laws and policies continue to evolve. The steps below can help ensure compliance with water rights law:
Research the law in your state and locality: In most western states, water rights law is based on the doctrine of prior appropriation. Under this doctrine, “the first in time” is the “first in right.” The right to use water is given to the first appropriator (the “senior appropriator”) who put the water to beneficial use. The senior appropriator has the right to use the water before later users (“junior appropriators”). Appropriation rights may be held by individuals, corporations, public utilities, partnerships, cities, state governments, and the federal government.
The impact of state water rights law on the feasibility of green infrastructure practices varies by state. In some states, the prior appropriation doctrine does not affect green infrastructure practices because the state does not have jurisdiction over precipitation. In other states, precipitation is subject to appropriation and particular green infrastructure practices may be restricted or prohibited. If a water rights issue arises, some states may require permits or design modifications for certain green infrastructure projects. Before designing a green infrastructure project, several questions must be asked, including:
- Does the state have jurisdiction over precipitation?
- Does the green infrastructure project retain, use, or otherwise consume precipitation?
- Will the design of the project affect the water rights of others?
- Will this particular green infrastructure project require a water right?
Contact the agency in your state or locality that handles water rights issues: Project designers should consider contacting the appropriate state agency to find out more about water rights when developing a green infrastructure project. The following agencies handle water rights in the Western states:
State State Agency Phone Number Arizona Arizona Department of Water Resources (602) 771-8649 California State Water Resources Control Board Division of Water Rights (916) 341-5300 Colorado Colorado Division of Water Resources (303) 866-3581 Idaho Idaho Department of Water Resources (208) 287-4800 Kansas Kansas Department of Agriculture, Division of Water Resources (785) 296-3717 Montana Montana Department of Natural Resources and Conservation, Water Resources Division (406) 444-6601 Nebraska Nebraska Department of Natural Resources (402) 471-2363 Nevada Nevada Division of Water Resources (775) 684-2800 New Mexico New Mexico Office of State Engineer (505) 827-6091 North Dakota North Dakota State Water Commission (701) 328-2750 Oklahoma Oklahoma Water Resources Board (405) 530-8800 Oregon Oregon Department of Environmental Quality (503) 229-5696 South Dakota South Dakota Department of Environment and Natural Resources (605) 773-3151 Texas Texas Commission on Environmental Quality (512) 239-4691 Utah Utah Division of Water Rights (801) 538-7240 Washington Washington State Department of Ecology, Water Resources Program (360) 407-6872 Wyoming Wyoming State Engineer’s Office (307) 777-6150
Understand what projects have already been completed in your state or area: Some states and localities encourage particular green infrastructure projects. Some examples of green infrastructure projects in Western states include:
- Rainwater harvesting programs in several California cities, including Los Angeles
- Roof gardens and rain gardens at libraries in Tulsa, Oklahoma.
- Green roofs in Omaha, Nebraska
These are only some of the examples of green infrastructure projects in Western states. More projects can be identified by visiting our Case Studies page.
Unfamiliarity with Maintenance Requirements and Costs
Many local governments are reluctant to pursue green infrastructure because they are unfamiliar with the maintenance needs of green infrastructure practices. The placement of green infrastructure practices on private property also poses a challenge. When green infrastructure is located on private property it is difficult for public agencies to ensure that proper maintenance is occurring. Sometimes stormwater facilities are even filled in or removed during landscaping projects by private owners who are not aware that the facility is an important part of a stormwater management system.
Recognize that all infrastructure requires maintenance: Like conventional stormwater systems, green infrastructure facilities require periodic maintenance. Conventional stormwater filters that are not maintained, for example, will eventually become clogged with sediment and debris and fail to remove pollutants. Maintenance requirements vary depending on the facility, and they may be as simple as weeding a vegetated swale or removing debris from curb cuts. In general, the maintenance of green infrastructure practices require more manual labor and less heavy equipment than the maintenance conventional stormwater controls.
Consult whole life cost tools: The whole life cost models developed by the Water Environment Research Foundation (WERF)
Develop a maintenance program: Many local governments are developing maintenance programs for green infrastructure facilities within their jurisdiction. Two municipalities with particularly extensive experience operating green infrastructure maintenance programs are Portland, OR, and Seattle, WA. Portland employs three full-time staff to maintain and manage its green streets, and relies on other government bureaus to help with construction inspection and community outreach. Portland also contracts with private landscape and reforestation companies to provide maintenance, with contract lengths typically three to five years. Contractors are trained in managing green streets to avoid damaging plants and to use correct techniques for weed removal. To provide cost efficiency, Portland batches its green street maintenance work by location and performs quarterly maintenance. Seattle has developed a Green Stormwater Operations and Maintenance Manual (PDF) (25 pp, 4.6MB, About PDF)
Develop communication and outreach materials for private property owners: As more facilities are installed on private property, private property owners will need to be educated about green infrastructure facilities on their properties and about their maintenance responsibilities. Communication materials should describe the benefits of green infrastructure and how it functions. Portland has developed an Operation and Maintenance Guide for Private Property Owners
Conflicting Codes and Ordinances
In some cases, staff in a local environmental department may be interested in promoting green infrastructure, but existing requirements in comprehensive plans, zoning codes, and building standards may be silent on, ambiguous towards, or even in conflict with the principles of green infrastructure. Zoning density standards, storm sewer connection requirements, and minimum parking and road widths are just a few of the requirements that can limit opportunities for green infrastructure. The following steps can help municipalities remove some of these obstacles from local codes and ordinances.
Conduct an audit of local codes and ordinances: Several audit tools are available to help municipal leaders identify the barriers to green infrastructure in local codes and ordinances and collaboratively develop solutions. These audit tools include the Center for Watershed Protection’s Better Site Design Codes and Ordinances Worksheet
Amend local codes and ordinance: By integrating the principles of green infrastructure into stated goals and adding language that provides flexibility for green infrastructure, municipal leaders can craft codes that facilitate green infrastructure approaches. EPA’s webcast on Updating Local Codes to Cultivate Green Infrastructure provides many examples of amendments to statements of purpose or intent, as well as to curb and landscaping requirements. As a rule of thumb, “anything with the words ‘roof,’ ‘curb,’ ‘edge,’ or ‘tree’ needs to be audited.”
Develop design guidance: To remove all trace of ambiguity towards the use of green infrastructure, municipalities can supplement language providing flexibility for green infrastructure with design guidelines demonstrating acceptable green infrastructure designs. Design guidance can also introduce engineers and public works staff who are unfamiliar with green infrastructure to these techniques.
Lack of Government Staff Capacity and Resources
Updating development codes; educating builders, developers, and the public; and inspecting and maintaining stormwater facilities all require government staff and funding. Many municipalities cite their lack of resources as one of the most significant barriers to implementing green infrastructure projects and policies.
Recognize avoided costs: Though local governments have limited resources for reducing stormwater impacts, these services need to be provided, or the public will continue to pay the greater costs of restoring degraded streams, recovering endangered species such as salmon and steelhead, and cleaning up polluted water and river bottoms.
Establish stormwater utility: Some local governments, recognizing the costs involved in providing stormwater management services, have created a stormwater utility that is funded by a fee. In most cases the fee for homeowners is very small. The stormwater utility fee can become an incentive for on-site stormwater management if a fee reduction is offered. The City of Portland, for example, offers a stormwater fee discount for on-site stormwater management through its “Clean River Rewards
Many developers are unaware of the potential for cost savings with green infrastructure. Even when developers are aware of the potential for cost savings, however, they may find it impossible to reconcile green infrastructure approaches with other codes and standards. Many of the strategies for overcoming these barriers require action by municipalities.
Skepticism about Long Term Performance
Many developers perceive green infrastructure practices as emerging technologies with a limited track record. They are reluctant to take on the risk that these practices may have to be repaired or re-installed.
Learn about national and local experience: Researchers and engineers have gathered extensive data on the volume reduction and pollutant removal performance of green infrastructure practices (see Performance Research), and several cities with an exceptional commitment to water resource protection have at least 10 years of experience with green infrastructure (see Library). Several inventories and collections of case studies are also available to find green infrastructure practices near you, including the NEMO LID Atlas
Learn about design variations: Green infrastructure approaches are extremely flexible and may be adapted to a range of climate regimes and soil characteristics. Design strategies are discussed below.
Proper installation is key: When green infrastructure practices do fail, it is often because they were not installed properly. Construction procedures and sequencing for green infrastructure sites differs from conventional sites, and contractors should be aware of these differences. The Designer’s Guide for Low Impact Development Construction (PDF) (126 pp, 13MB, About PDF)
Perception of Higher Cost
Many developers do not consider managing stormwater with green infrastructure because they suspect that green infrastructure will cost more to install.
Recognize avoided costs: When the avoided costs of stormwater ponds, pipes, paving, clearing, and grading are taken into account, green infrastructure is often as cost-effective as (if not more cost-effective than) conventional approaches to stormwater management. These Cost Analyses quantify many of the avoided costs associated with green infrastructure.
Recognize potential to add value: In some cases green infrastructure may add value to projects by adding buildable lots or increasing market prices. When the need for stormwater ponds is eliminated, developers are sometimes able to add more lots to development projects. Also, many consumers perceive attractive landscaping and green space as an amenity, and will be willing to pay more for lots in close proximity to these amenities. Several studies documenting the value of green space are included in the Economics section of our Library.
Municipalities, developers, and engineers often express skepticism that green infrastructure is appropriate for their particular context. For example, green infrastructure is often perceived to be limited to sandy or loamy soils. Green infrastructure practices are extremely versatile, however, and strategies exist to overcome most design challenges.
Clay or Glacial Till
Clay and glacial till often have low infiltration rates. For sites dominated by these soils, engineers may therefore assume that infiltration-based stormwater controls are not feasible. While the design of green infrastructure practices for sites with these soils may require greater care, many steps can be taken to design green infrastructure practices that meet water quality goals.
Measure soil infiltration rates: By determining the infiltration rate of site soils before beginning the design of stormwater controls, designers can avert unwelcome and costly surprises. Guidance materials generally recommend that the infiltration rate of native soils beneath infiltration practices be greater than 0.25 – 0.5 inches/hour. For a cautionary tale on the dangers of not incorporating measured infiltration rates into rain garden design, read about Seattle Public Utilities’ experience with the Ballard Roadside Rain Garden pilot project (PDF) (10 pp, 318K, About PDF).
Amend soils beneath infiltration practices: Amending clay soils with compost or other organic matter can increase soil infiltration rates, while improving soil fertility and improving the ability of the soil to remove pollutants. The LID Center has developed a design specification
Plant deep-rooted vegetation: Deep-rooted vegetation enhances soil infiltration rates by creating small conduits for water to infiltrate and increasing biological activity in the soil. A 2010 report (PDF) (82 pp, 5.3MB, About PDF) by the U.S. Geologic Survey found that the median infiltration rate of a clay soil planted with prairie species (0.88 inches/hour) was more than three times the median infiltrate rate of a clay soil planted in turf (0.28 inches/hour).
Expand the storage layer and include an underdrain: Even when soil infiltration rates limit the volume of stormwater that can percolate into the groundwater, including a larger storage layer with an underdrain can significantly slow peak flow, protecting stream banks, and potentially reducing combined sewer overflows.
Use practices that do not require infiltration: Rainwater harvesting, green roofs, vegetated swales, and practices designed for peak flow attenuation do not require soils with high infiltration rates. These practices may be integrated into treatment trains to mitigate stormwater impacts.
Sediment Laden Stormwater
In arid regions, bare soils are more common and rates of erosion and sedimentation are relatively high. Fine sediments delivered by stormwater flows can clog infiltration practices and degrade their performance. Here we summarize a few strategies that stormwater professionals have applied to design and maintain effective green infrastructure practices in areas with high sediment loads.
Include a mulch layer: Mulch acts as a filter for the sediments carried in stormwater. By including a mulch layer above infiltration practices and replacing this layer when it is filled, the soil and gravel layers below can be protected from sedimentation.
Include a sediment trap: A sediment traps is a small depressions bordered by a small berm that captures and collects sediment at the entrance to a bioretention area. Traps can be used at the inflow of many green infrastructure features to facilitate the removal of accumulated sediment and prevent the feature from becoming clogged.
Perform periodic maintenance: If a mulch layer or sediment trap is included, the accumulated sediment must be regularly removed to maintain the function of the stormwater management practice.
Cold Weather
Stormwater professionals frequently raise questions about the performance of green infrastructure practices in cold weather. Research by the University of New Hampshire Stormwater Center indicates that green infrastructure practices in their climate demonstrate excellent water quality treatment and peak flow reduction year round.
indicates that green infrastructure practices in their climate demonstrate excellent water quality treatment and peak flow reduction year round.
Limited Water Supply for Irrigation
Many stormwater professionals cite limited water resources as a barrier to green infrastructure in arid and semi arid regions. By following the principles of xeriscaping, however, green infrastructure practices can conserve water resources:
Create a plan. The first step in designing landscape features that can remain healthy and attractive with limited irrigation is to create a plan balancing water supply and demand. Annual water budgets will generally be appropriate for landscapes consisting of native plants at native densities, while monthly water budgets will be more effective for landscapes with exotic plants higher plant densities.
Use low water use plants. Native and drought tolerant plants can drastically reduce, if not eliminate, the irrigation requirements of green infrastructure practices.
Use efficient irrigation systems. Irrigation systems will be most efficient when plants are grouped according to their water needs, and when the frequency and depth of irrigation is adjusted according to plant type, plant maturity, and season.
Consider soil amendments. Healthy soils are essential to retain soil moisture, sustain vegetation, and treat stormwater runoff. If site soils are poor, soils can be amended with organic material.
Use mulches. Organic mulch can increase water retention and pollutant removal while building soil structure and suppressing weeds. Note, however, that many desert trees and shrubs react poorly when their trunks come in contact with mulch.
Maintenance. All landscapes require maintenance and xeriscaping is no exception.
Space Constraints
Many green infrastructure features require land area to allow stormwater to infiltrate into the soil. This can pose a challenge when space is limited, for instance in a retrofit project or in a right-of-way. Designers have developed many strategies, however, for overcoming this challenge:
Use features that serve multiple purposes: Swales and bioretention areas can be integrated into landscaped areas, medians, or parking strips. Similarly, permeable pavements provide volume reduction and water quality treatment without requiring any additional space.
Use features that fit into small spaces: Planter boxes and tree pits are examples of green infrastructure features that may be designed to fit into small spaces.
Subsurface storage or infiltration: Subsurface storage or infiltration tanks provide an alternative when space is too limited for any surface practices.