By R. Patrick Worzer
Photos by GatewayDesignStudio
Parks and recreation professionals have the opportunity to be at the forefront of implementing green infrastructure within parkland and recreational complexes. While this infrastructure has been increasingly utilized over the past 10 years, green applications tend to be focused on public works and specialized private development projects, such as LEED. Parks have the opportunity to position themselves as an important resource for municipalities, helping to lead the way in the continuously growing field of water-resource mitigation and conservation.
The Environmental Protection Agency (EPA) defines green infrastructure as “an array of products, technologies and practices that use natural systems—or engineered systems that mimic natural processes—to enhance overall environmental quality and provide utility services.”
This article will focus on some of the strategies that can most effectively be applied to parks.
The following practices rely heavily on the conservation of existing drainage networks, as well as engineering structured soils and specialized plants to detain and retain storm water. They are considered part of green-infrastructure planning:
Rain gardens and bio-swales
Rain barrels and below-ground cisterns
Trees and enhanced street tree pits.
Other aspects of green infrastructure may include the preservation, restoration, or enhancement of larger patches and corridors of vegetation, such as forests, floodplains, stream corridors, and wetlands. These areas can often be found within parklands and provide a great resource for park managers to use for effective storm-water control and enhanced environmental quality within a community.
1. Rain Garden Systems
Defined as landscaped depressions that filter storm-water runoff with specialized plants and possible under drains, rain gardens have been used for many years to provide water-quality treatment. Typically, these systems contain specialized plants and soil conditions that provide a means for maximum capture and permeation of surface drainage. Rain gardens can range in size depending on the drainage area and required mitigation. Though effective for many small areas, these landscaped depressions require seasonal maintenance of the plant material. Also, after several years of use, the basins may need to be excavated and the soil mix replaced in order to provide effective infiltration. Careful analysis and determination of the drainage area should be considered when using rain gardens. Consult a reputable local landscape architect and engineer to effectively design these structures.
2. Cisterns/Rain Barrels
Cisterns are typically below ground, while above-ground rain barrels can be used to detain rainwater and stored for later use. These systems can be incorporated many times into various uses, like in recreation centers or maintenance buildings. The key to success for using this infrastructure method is to design the system so stored water can be reused for landscape beds around building areas or incorporated into a non-potable irrigation system. It is important to recognize that an appropriate design of these types of systems is required. Proper engineering and pump systems are necessary to provide sufficient watering to desired areas.
3. Porous Pavement
Porous pavement may include special asphalt, concrete, or spaced paving, enabling water to infiltrate soil, evaporate, or drain appropriately. These pavement systems perform at various degrees based on the amount of water that’s mitigated and what a budget may allow. For a parks and recreation application, porous pavement can be incorporated in parking lots, loading zones, trails, and walkways. Special attention must be paid to ensure the pavement is designed in alignment with the existing soil conditions. Proper engineering with a soil investigation and geotechnical report will guide recommendations for the excavation, thickness of base material, and pavement. These pavement systems require bi-annual maintenance, which includes vacuuming the surface to ensure that porosity is at a maximum.
Municipalities and park departments can set an example by showcasing a range of green-infrastructure systems that will validate development incentives and directives. These investments will familiarize city staff and their private-sector colleagues with the maintenance, installation, and best-practices techniques. Some of the systems that may be incorporated into the existing fabric of the community and park space include bio-swales, providing additional trees and implementing street tree pits along roadways. These additional systems can be retrofitted into parks depending on the conditions, which may warrant further storm-water mitigation.
Bio-swales consist of sloped drainage areas filled with vegetation, soils, and/or stone to direct, infiltrate, and filter storm-water runoff. These drainage ways serve as an important means of capturing runoff and mitigating storm water by reducing flow and providing treatment of pollutants. Many times, bio-swales are designed as part of surface drainage off of parking lots. They can also be designed for drainage ways between athletic fields where proper runoff is the key to a quick turnaround for play conditions after a storm. Appropriate design of a bio-swale requires proper specification of soils and plants to allow for maximum performance. With suitable planning, this type of system can be a low-cost and effective option to integrate into drainage-mitigation plans.
2. Trees And Enhanced Street Tree Pits
Trees have a simple and important purpose in an integrated green-infrastructure system. Incorporating trees into drainage plans helps further mitigate runoff and stabilize soils. In addition, they help cool pavement areas by reducing the heat-island effect around buildings and recreational complexes. Look for opportunities to incorporate trees into parking islands that serve as rain gardens and along the edges of bio-swales or retention basins.
Enhanced street tree pits provide a unique opportunity along roadways where storm-water runoff is directed into these systems, instead of conventional inlets and pipes. These tree pits need to be designed to handle the required storm-water runoff volume and should be properly engineered to work effectively. Similar to rain gardens and bio-swales, this particular system requires specific plants, soil, and stone for proper infiltration.
Conservation areas within parks are a critical component to large-scale green-infrastructure management. Conserved land can be appropriated through easement and fee acquisition to maintain groundwater infiltration and reduce peak runoff events. By carefully planning regional and community parks, systems can begin to provide critical areas for conservation and storm-water mitigation.
Wetlands, Stream Corridors, And Flood Plains
As many people are aware, wetlands, stream corridors, and floodplains provide sensitive hydrological functions that protect storm-water storage capacity and minimize flooding. These natural, man-made, or restored systems are critical within parks, designated and used to mitigate storm runoff, and help protect developed land from flooding. In addition to the storm-water benefits, these systems also protect, enhance, and promote wildlife habitats, creating even more environmental benefits for the community. Contact your local state conservation department for further information and recommendations that may help a park system preserve these critical areas.
Slope And Erosion Control
Best Management Practices (BMPs) are man-made systems that help maintain slope and erosion control. These systems can be applied to parks when construction or disturbance of land is necessary for a variety of reasons. Park management must be aware of and responsible for proper installation of various measures based on the conditions and engineering needs. These erosion-control measures may include silt fences, siltation basins, rip-rap stone, geotechnical fabrics, and vegetative covering. When planning for grading or development within park land, coordinate with Public Works or an engineering consultant to properly determine necessary BMPs for the development site.
Challenges To Implementation
Below are common challenges faced when promoting and implementing green infrastructure in parks and a community:
1. Secure the space to construct these systems at the site, street, and municipal scale.
Success of green-infrastructure systems depends on locating and managing either a large number of properties and/or small designed systems, many times on private property or in streets, parks, or other public facilities that serve other purposes.
2. Acquire funding to pay for the implementation and management of green-infrastructure facilities.
Municipal governments are looking for alternative means of securing funding required to build these systems. Funding methods may include revising storm-water fee structures or implementing effective mitigation and credit policies to pay for development impacts.
3. Appropriate management to safeguard how systems are built and operated successfully.
In most cases, water and other capital-funding decisions are made by appointed agencies following traditional cost-sharing requirements and project-focused management. The green-infrastructure approach requires decision makers to operate outside their traditional process and accountability.
Alternative means of securing funding for parks and municipalities may be needed in order to build green-infrastructure systems. Methods for funding include:
1. Revising current fee structures so storm-water generators pay their fair share of treatment costs
2. Establishing effective mitigation and credit strategies to compensate for development impacts
3. Implementing lower-cost passive strategies instead of costly traditional infrastructure.
Resource: Storm-Water Fees And Incentives
Local government may impose storm-water fees that can be directed toward specific land uses and address conditions that produce the greatest challenges to water quality. Fees can be calculated based on property density, square footage, or impervious surface area. Larger impervious land uses, such as industrial and high-density commercial areas, pay more in fees whereas low-density residential and commercial areas pay less.
Resource: Mitigation Banks And Ecosystem Services Markets
Parks can provide valuable mitigation banks to improve the feasibility of redevelopment projects in urban and suburban centers where space is at a premium. Large-scale developments can be shared with other planning efforts, such as greenways and parks, providing additional hydrological and ecological benefits. Developers can purchase open space or wetland credits from parks to comply with development requirements. Cooperation between city governments and developers is important to the success of these programs. This approach can provide continued funding for further green-infrastructure development within a community.
Avoid Gray Infrastructure Costs By Going Green
Costs of conventional gray infrastructure can be costly. However, these costs can be offset by making the existing drainage network and infiltration the backbone of a system of streams, green streets, high-performance parcels, and park areas, providing storm-water goals without costly street-side storm drains and catch basins. This translates to less built infrastructure and lower, long-term maintenance costs. Conversion of conventional storm-water management to green infrastructure can be accomplished by evaluating the park system and determining what areas can be retrofitted to a greener approach.
The key to any implementation program is to start small and build on the success of previous projects. Once the green-infrastructure system is implemented and performing, it will be easier to expand to other areas.
Coordinate Powers And Responsibilities
One of the main challenges of green-infrastructure management is the inter-agency coordination needed to develop sustainable projects. Combining all aspects of storm-water management has empowered agencies to consider how individual projects measure up, contributing to the overall enhancement of public spaces. All departments should be invested in the green-infrastructure program from initial staff endorsement to concept, design/engineering, implementation, and maintenance. This holistic approach is the key to successfully making an impact within the parks and recreation system.
Encourage Innovation And Education
Lastly, communities can help build agency expertise and experience through pilot projects on public property; parks offer a great opportunity! In some cases, direct education is critical since public and private owners will become stewards of the green-infrastructure system. In order to expand and plan for future storm-water improvements, it is vital to show how new technologies apply to parks and recreation conditions through demonstration projects and educational programs. This approach is perhaps one of the most important aspects of any green-infrastructure program. Implementing green infrastructure into parks and recreation systems allows for a continuous opportunity to promote and educate the general public.
Whether your parks system is small or large, green infrastructure offers a great way to transform how storm water is managed within public spaces. Conventional storm inlets, piping, and detention basins have increasingly cost municipalities more time and money in construction and replacement. By carefully evaluating and determining which areas of parkland can incorporate green infrastructure, parks and rec departments can take the initiative and be at the forefront of this technology. It is important to mention that any project requires careful analysis, design, and engineering to achieve maximum results. Involving professionals who are experienced with and knowledgeable of green-infrastructure techniques and construction is critical to achieving success.
R. Patrick Worzer, ASLA, RLA, CLARB serves as the principal owner and design leader for Gateway Design Studio, LLC, a professional planning, landscape architectural and environmental design firm located in St. Louis, Mo. Worzer is a member of the following organizations; ASLA - American Society of Landscape Architects and MPRA-Missouri Parks and Recreation Association and is a Certified Professional with CLARB - Council of Landscape Architects Registration Board. Reach him at firstname.lastname@example.org.