Environmental Center of the Rockies
Demonstration Project-- Urban Storm Runoff


In 1990, the National Geographic Society, The Conservation Fund, and the U.S. Geological Survey launched an ambitious effort to make the American public aware of freshwater's value and the need to identify solutions to problems threatening the nation's freshwater resources.

As part of that campaign, the National Forum on Nonpoint Source Pollution was created. The Forum focused on developing and implementing specific actions Americans could take to eliminate nonpoint source (NPS) pollution. The Forum addressed this critical issue by identifying and demonstrating innovative, nonregulatory remedies for this pervasive water quality problem. Consisting of national leaders representing public, private, and nonprofit organizations, the Forum sought solutions that would balance the nation's economic and environmental needs.

Since passage of the Clean Water Act in 1972, many "point" sources of pollution from factories and sewage treatment plants have been successfully controlled. However, NPS pollution is now the nation's chief threat to water quality. NPS pollution comes from many diffuse sources and is brought about as rainwater and snowmelt wash off the land into streams, lakes, coastal estuaries, and marshes, or seeps into groundwater. As this runoff moves across plowed fields, city streets, or suburban backyards, it picks up soil particles, pesticides, fertilizers, animal wastes, and other pollutants such as road salt and crankcase oil. It is estimated to account for over half of our nation's water pollution and has harmful effects on drinking water supplies, recreation, fisheries, and wildlife.

The Forum's goal to develop, implement, and communicate to the public, remedies for NPS pollution based on market incentives, voluntary initiatives, and education was turned into 25 innovative demonstration projects spread across the face of our nation. Three of those projects are located in Colorado: Adopting Orphan Sites for Credit (Coors Brewing Company); Westerly Creek Restoration Project (Stapleton International Airport redevelopment); and Urban Stormwater Control Project (the Land and Water Fund of the Rockies).


When the Land and Water (LAW) Fund purchased the building located on the corner of Broadway and Baseline Road in Boulder, Colorado, the intention was to create a model for "green" architecture. After consulting with an environmentally oriented architectural firm located in Boulder, the LAW Fund remodeled the 10,000-square-foot structure. The building retrofit includes reflective windows, a new roof made from recycled materials, and installation of solar collectors on the roof.

To mirror the energy savings to be achieved in the building, the LAW Fund resolved to create a landscape plan using native, drought-resistant plants. When it was learned that 70% of pollutants reaching Boulder Creek were attributable to nonpoint sources, the LAW Fund was inspired to do more. Thus, the Urban Stormwater Control Project was initiated. The LAW Fund began construction of a "closed-loop" landscape that would retain stormwater on-site rather than allowing it to flow directly into the City's watercourses. The overall goal for this project is to create a national pilot project demonstrating how a conventional business or residential landscape can be improved to cleanse pollutants retained in storm-water runoff.


Now that the venture had evolved from a water-conservation garden to an Urban Stormwater Control Project work began in earnest to study the site and research data regarding microclimates, storm-water flows, and hundred-year flood levels. The plan developed by Denver's Wenk Associates and Joan Woodward, ASLA, an associate professor of landscape architecture at California State Polytechnical University in Pomona, was to synthesize the empirical approach to create something more like a garden than a "detention" pond. Indeed, the schematic drawings of Woodward's ideas, developed in collaboration with William Wenk, FASLA, seemed to set the building among amber waves of grasslands rather than adjacent to a road that handled 30,000 cars daily.

It was soon discovered that meeting the goal of cleansing storm water also achieves the water-conservation initiative. The project's two swales and gardens (planted in soil improved with the addition of sandy loam) will sponge up runoff up to the level of the first flush that contains most pollutants. This amount of water turns out to be fully half the level of a hundred-year flood. Waters beyond the five-year level will simply wash into the alley.

For the first two years, drip irrigation will nourish the new plantings. Once plants are established and healthy, the drip lines will be removed. By that time, plantings should thrive on rainwater and runoff alone.

In July 1998, the LAW Fund's parking lot was reconfigured and reduced in size from 35 to 27 spaces. Water will collect at a high point at the site's northwest corner and course down an eight-foot elevation drop through the two swales. One swale will head straight south to water the parking lot's six new shade trees. The team ruled out the idea of laying down permeable paving (that is, asphalt that would allow rainwater and snow melt to percolate through to the water table) because Boulder's clay-rich soils already tend to expand and weaken building foundations. Additionally, permeable paving can clog, necessitating more frequent repaving, so recycled asphalt was used.

Storm water from the parking lot is now directed to plants and trees in the lot itself and at the front of the building. Sand and grass filters placed at the edge of the landscaped area are designed to remove the coarsest waste from the parking lot stream. A buried landscape barrier prevents waste from permeating into expansive soils, while porous earth in the bottom of the swale removes finer particles and pollutants. Expansion of a garden-level patio and using a system of landscape terraces has created a small outdoor amphitheater for educational programs. Plants here will be watered by runoff from the roof.

Shallow ponds have been created on the north and east sides of the building, replacing much of the original plant overgrowth. Also, an extra sidewalk and shrubs were removed from the east and north sides of the building to make way for native plants in individual micro-climates. A diverse combination of upland grasses, moist area grasses, perennials, riparian plantings, and trees help to filter the urban pollutants from the building and parking lot runoff. This new design will virtually eliminate the need for watering. Surrounding materials for the purpose of collecting, filtering, holding, and reusing the storm water include: drainage fabric, sandy loam backfill, gravel mulch, waterproof membranes, aggregate mulch, and gravel wrapped in geotextile.

The goal for our landscape project is to capture most of the water that falls on the site, with the remainder flowing into storm drains. The filtering and cleaning process ensures that most of the water that reaches city waterways is clean.

Ongoing monitoring and evaluation will be necessary to ensure the project is accomplishing its' goals. A long-term maintenance plan will be put in place while ongoing maintenance will be easier and cheaper (no more lawnmowers and weed whackers or need for pesticides.

The Environmental Center of the Rockies' demonstration project is linked to the BASIN project by researchers at the University of Colorado where graduate students under the guidance of Dr. James Heaney are helping to monitor and analyze data from the project which will provide information on storm runoff and issues relating to non-point source pollution of waterways.

We hope this site will prove so successful that it will serve as a prototype for other landowners in the City of Boulder and elsewhere—a concept that will minimize urban impacts on the natural world around us. If you are in our neighborhood, please stop by and see this sustainable landscape project for yourself.

For more complete information on this project, see Technical Summary and Detailed Analysis and visit the Environmental Center of the Rockies website.

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Photos ŠLen Wright; Colorado University


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