UT as an Ecosystem
Low Impact Development Project Researcher
Ecosystem Design Group
Lady Bird Johnson Wildflower Center
Ecosystem Design Group
Lady Bird Johnson Wildflower Center
A large portion of The University of Texas Main Campus is currently impervious surface, and its landscape areas are covered with turf grass and other plants in raised planter beds. These types of surfaces require regular maintenance—often including the use of air polluting mowers and leaf blowers—and irrigation, both costly and potentially wasteful practices. Campus staff and administrators have recently demonstrated their interest in constructing and retrofiting campus buildings to be more energy-efficient (even attaining LEED certification) and use sustainable materials; and a part of this momentum also includes a trend toward using more native plants. But native plants alone do not provide enough ecological performance to warrant a sustainable landscape label or to indicate sustainable performance. The campus landscape should be regarded as a system, continually providing ecological performance and function in concert with buildings, rainfall, campus use, or aesthetic goals.
The Lady Bird Johnson Wildflower Center defines a sustainable landscape as one that performs and functions to produce measurable benefits. A landscape’s performance is measured through ecosystem services. Ecosystem services are good and services of direct or indirect benefit to humans that are produced by ecosystem processes involving the interaction of biotic (e.g. vegetation, soils) and abiotic elements (e.g., rock, air).1 Due to research in the late 1990s conducted by economists, along with the release of the 2005 UN Millennium Ecosystem Assessment, the link between environmental well-being, human well-being, and economic prosperity continues to gain traction.2 In simplest terms, “We need a healthy environment because we need clean water, clean air, wood and food.”3 Thus, a sustainable landscape provides ecological function, and brings the essential importance of ecosystem services to the forefront of site development and management. These landscape performance goals have been codified by the Sustainable Sites Initiative (SITES™), which recognizes that “any landscape…holds the potential both to improve and to regenerate the natural benefits and services provided by ecosystems.”4 A major opportunity we see to maximize landscape performance and function on the UT campus is to layer current and future campus landscaping and water resources into a distributed stormwater system often referred to as Low Impact Development.
Low Impact Development Approach to Stormwater Management
Low Impact Development (LID) is a comprehensive approach to site planning, design and pollution prevention strategies that creates a more economically sustainable and ecologically functional urban landscape. LID works with nature to manage stormwater as close to its source as possible, treating stormwater as a resource, rather than a waste product. When designed appropriately, LID is a tool that can work in any eco-region, climate or land use typology. Implementing LID principles and practices allows water to be managed in a way that reduces the impact of built areas and promotes the natural movement of water within an ecosystem or watershed. On a regional scale, LID can maintain or restore a watershed's hydrologic and ecological functions. A number of water quality problems and impairments in Texas are attributed in full or in part to urban stormwater runoff carried through storm sewers and channelized streams.
Treating water as a resource is one of the guiding principles of SITES.™ Rather than getting rid of stormwater, a more sustainable approach is to find ways to capture it on site and use it for irrigation, ornamental features, drinking water or groundwater recharge. The Site Design-Hydrology chapter of SITES™ provides two of many target benchmarks applicable to improving UT’s sustainable landscape from a water standpoint: one for managing stormwater on site, and two, for protecting and enhancing on-site water resources and receiving water quality. The former describes ways to design a site to maintain or restore the water balance. A common approach is to increase the water storage capacity of a site by means of infiltration, evapotranspiration, and water harvesting/storage. The result is less water leaving the site and less erosive volumes of water entering downstream waterbodies. The latter credit awards points for the prevention and mitigation of common watershed pollutants of concern. Points are awarded based on the overall %age of water volume leaving a site that receives treatment for pollutants of concern. Potential technologies and techniques include tools that filter and infiltrate stormwater.
LID in Action on University Campuses
One of the best ways to communicate an idea is to see it in practice. With this in mind, UT has the opportunity to implement LID techniques and tools on the main campus to provide valuable ecosystem services (on an urban campus, often where these services are needed and valued most) and a chance to join these functions with campus landscape priorities and research goals. Similar large universities have already taken this step for a myriad of reasons to reduce long-term landscape maintenance costs and burdens, to increase the use of native plants on campus, to clean and filter stormwater, or to reduce the requirement for large-scale stormwater conveyance or retention systems. Universities taking the next step to retain and cleanse stormwater on site include the LA Community College District, University of Arizona, Portland State University, University of Maryland (UMD), Texas A&M, Oklahoma State, North Carolina State, University of New Hampshire, University of Texas – Arlington, and Houston Community College, to name a few.
To provide a more detailed example, the UMD campus serves a total of nearly 38,000 students on approximately 1,000 acres. In 2002 the campus became a member of the Anacostia Watershed Restoration Partnership which works to restore the priority Anacostia watershed, part of the larger Chesapeake Bay watershed. Recognizing its role in overall watershed health, efforts are underway to better manage runoff from impervious surfaces throughout campus. In 2007, campus drainage was evaluated comprehensively to identify stormwater pollution and stream degradation areas. The campus was then categorized into 23 sub-watersheds delineating storm water drainage systems. Knowing these patterns creates better opportunities for designing, funding, and implementing future water quality improvement projects. From 2007-2010, the school invested in several notable water features and technologies that receive stormwater runoff from campus land, rooftops, roads, and parking lots. These interventions include underground cisterns, restored riparian buffers, green roofs, biofiltration devices, and pervious pavements. Part of this initiative also includes a national LID student design competition to develop additional ideas and opportunities for making the campus landscape more sustainable in its treatment of stormwater.5
Due to the urban nature of the UT Campus with dense building footprints and high impervious cover, the ecological function of the campus can be greatly increased through LID practices. Restoring ecosystem services to urbanized areas is a priority to SITES™ because those are the locations where they are most lacking and where increasing ecosystem services has great potential for human benefit.6 Thus, we propose a systematic view of looking at the campus as a whole to identify areas where LID would be of greatest benefit.
LID at the University of Texas
The methodology for locating LID within the UT campus begins with viewing the campus as an ecosystem— a dynamic place where there are transfers of flows and energies and a general interconnectedness and dependence upon those processes. More specifically, the campus should be viewed as a watershed with nested, contributing, and adjacent watersheds. Through this lens we are challenged to avoid viewing any potential LID developments in isolation. When we understand the campus to be an ecosystem, it helps also inform proper LID placement to maximize the potential benefits to the system.
Drawing from methodology used to develop an assessment model for the Upper San Antonio River watershed,7 we suggest looking at multiple factors to assess priority areas for LID implementation on the UT campus. Inputs to be considered are: topography and drainage patterns, impervious cover, footprint densities, land use (i.e. parking, road, industrial, recreational, open space), soil types, potential pollutant loadings, surface hydrology, climate and rainfall data, proximity to impaired waterbodies, vegetated buffers, and presence of sensitive natural resources. These inputs help inform degrees of environmental health and asses site specific needs in regard to LID.
The most effective way to identify priority areas would be to combine these inputs into geospatial data overlays, assign parameters, and then assign weights to each factor. As a hypothetical example for UT campus, one could first examine the geospatial data associated with the entire UT campus. After applying the inputs and parameters across the site, specific sites could emerge as ideal locations for LID. For instance, an area may emerge within a catchment basin with 70% or more impervious cover and adjacent to Waller Creek, an impaired waterbody. When compared to other locations across campus, this site is given a higher priority (or weight) and would therefore be an ideal location for LID implementation.
Once the location is selected, the size of the LID feature should be based upon the physical conditions and referencing local code recommendations. The size of a biofiltration feature is defined by the capture area (the amount of surface water entering the feature), the rate of infiltration, and the allowable ponding depth. Any changes to these components will influence the feature’s size. For example, if the infiltration rate is slow due to soil type then the size of the feature will need to increase to meet the ponding depth requirement.
Benefits LID Provides to the UT Community
The implementation of LID practices through the example methodology described above has many benefits for the University community. Because LID is a fairly new practice, there is enormous potential for UT to become a leader and expert in the field. First, many components of LID technologies are still under debate. For instance, there is much debate about the ingredients of biofiltration media and the planting mix for vegetated LID systems. More research is needed to discover whether certain local recycled components such as compost, crushed glass, or rice hulls could be an appropriate substitute for mined materials such as sand and peat.8 Second, also due to LID’s infancy, there is a need for monitoring data on real world features. While monitoring information is slowly growing, performance monitoring is still not widely practiced on most LID projects. Acquiring monitoring data from LID systems greatly influences future design and implementations.
Most importantly, implementing LID on the University campus has multiple educational opportunities. The School of Architecture could be involved in the location and design of these practices; the College of Natural Sciences and the Cockrell School of Engineering could help with soil, plants, monitoring and modeling components; the McCombs Business School could asses cost savings and provide an economic feasibility analysis for the University; and faculty from the Education, Marketing, and Communication disciplines could be involved in outdoor classroom course development, interpretation opportunities, and public outreach. The most beneficial approach would be to have an interdisciplinary process where each of the disciplines would inform and strengthen the other.
Implementation Challenges and Opportunities at UT
Two of the biggest obstacles we learned about from state-wide LID workshop series are the up-front cost and long-term maintenance concerns associated with LID implementation. While LID retrofits can be expensive in the short-term, long-term economic benefits from reduced irrigation and maintenance costs may be possible. While ongoing maintenance is important in optimizing LID performance, LID features can be designed such that supplemental irrigation or mowing are unnecessary, depending upon the design and performance goals. Most LID maintenance is focused on removing any large floatables or volunteer species that have entered the plantings;9 another opportunity to involve students to relieve any maintenance burden on UT landscaping staff. A final educational opportunity could be developing a maintenance training program that would address a growing green collar employment need in our community and on the UT campus. Including students in the assessment, development and maintenance of LID features can help address these potential University concerns, and provide greater benefit in return through scientific discovery.
In conclusion, LID implementation is encouraged on the UT campus for the variety of ecosystem services and educational opportunities it can provide. LID’s primary focus is on improving water quality however there are multiple other possible services ranging from hydrological water conservation services, reducing heat island effect and increasing biodiversity and wildlife habitat to increasing the quality of life for all of those millions of people who experience the University campus.
Through the use of LID, water will be used as a resource, and campus irrigation costs could be reduced. Using eco-regionally appropriate landscape would provide a sense of place and identity to the campus. Educational opportunities would add to the richness of the course offering and would offer students important real world experience and research opportunities. On site resources such as Waller Creek would be protected and potentially enhanced. Most importantly the campus would be a model for the larger community of responsible sustainable stormwater treatment. All water entering and leaving the UT campus would be valued, used, and cleaned, and UT would truly be a catalyst for change.
- Robert Costanza et al, “The value of the world’s ecosystem services and natural capital,” Nature 387 (1997): 253.
- Gretchen Daily. Nature’s Services: Societal Dependence on Natural Ecosystems (Washington, D.C.: Island Press, 1997).
- Jared Diamond. “The Last Americans: Environmental Collapse and the End of Civilization,” Harper’s Magazine (June 2003).
- Sustainable Sites Initiative. Guidelines and Performance Benchmarks, 2009. www. sustainablesites.org.
- University of Maryland Campus. 2010. Sustainability: Infrastructure and Operations: Stormwater. Accessible at: http://www.sustainability.umd.edu/content/campus/ stormwater.php.
- Rudolf S. de Groot et al, “A typology for the classification, description and valuation of ecosystem functions, goods and sercices,” Ecological Economics 41 (2002) 393.
- California State Polytechnic University, Pomoma, Studio 606, “Modeling Change: Locating Opportunities for LID in Urban Areas,” http://texaslid.org/page. php?page=resources#tx_manuals.
- Julian Cleary et al, “Greenhouse Gas Emissions from Canadian Peat Extraction, 1990-2000: A life-cycle analysis,” AMBIO 34 (2005): 456.
- William Lord and William Hunt, “Stormwater BMP Inspection and Maintenance Program in North Carolina—A 3 Year Update” (paper presented at the Low Impact Development 2010: Redefinding Water in the City ASCE conference, San Francisco, April 11-14, 2010).