The Snow Creek Stream Environment Zone (SEZ) restoration project in North Lake Tahoe, Placer County, Calif., has earned the Envision Platinum award for infrastructure sustainability — the highest level attainable in the Institute for Sustainable Infrastructure (ISI) Envision rating system and the first platinum rating awarded by ISI.
Envision is the product of a joint collaboration between ISI, which was founded by three national engineering associations (American Society of Civil Engineers, American Council of Engineering Companies, and American Public Works Association) and the Zofnass Program for Sustainable Infrastructure at Harvard University Graduate School of Design. Information about ISI and Envision can be found on the ISI website at www.sustainableinfrastructure.org.
The Snow Creek project site is located about 1.5 miles from Lake Tahoe’s north shore in the community of Tahoe Vista and is adjacent to Snow Creek, a tributary of Lake Tahoe. Since the early 1950s, the land uses surrounding the project area consisted of various industrial, commercial, and residential activities, including low income housing in the form of a densely populated trailer park. The project site itself was used for a concrete plant to support rapid development in North Lake Tahoe triggered by the 1960 Winter Olympics in Squaw Valley.
Prior to its development, the site included pine forested uplands, wetland meadow areas, and an ephemeral channel draining an approximately 200-acre watershed to Snow Creek. Development of the site occurred over time and included the placement of large amounts of soil fill and concrete debris and byproducts over the meadow and other areas until approximately three-and-one-half acres had been filled or graded. The ephemeral channel was relocated to route drainage around the site, which also carried increasing amounts of untreated stormwater runoff from development upstream. The concrete fill materials subsequently raised the soil pH, and hydrocarbons from fuel storage and equipment maintenance activities also impacted site surface and subsurface materials. Stormwater runoff from the site was mostly untreated and carried significant sediment and other pollutants to Snow Creek and Lake Tahoe.
During implementation of a community-wide water quality improvement project in 2004, the concrete plant property was identified as a significant pollutant source to Lake Tahoe. At the time, the property was privately owned but also on the market for sale. Based on the site’s high potential for
improvements to water quality, aesthetics, and public open space, the county decided to pursue grant funding and subsequently purchased the property for restoration with a grant from the Sierra Nevada Conservancy. To implement the project, the county obtained additional grant funding from the U.S. Environmental Protection Agency (EPA) Brownfields Program, the Bureau of Reclamation with the Department of the Interior, the State of California Resources Agency, the California Abatement Account, the Tahoe Regional Planning Agency Water Quality Mitigation Fund, and the North Lake Tahoe Resort Association.
Once the property acquisition process was completed, the county enlisted CDM Smith’s planning and design services to implement a multi-objective project through a stakeholder-driven process and create a valuable new amenity on Lake Tahoe’s north shore. Old structures, underground storage tanks, and contaminated fill materials were removed and the site was re-graded to create new channels and floodplain areas and restore SEZ and upland habitat. A new multi-use path links to other trails and provides public access to restored and previously undisturbed areas, including interpretive signage to educate the public about the project and the critical environmental role of SEZs in the Tahoe basin. The salvaging and reuse of materials such as rock, native soils, wetland sod, and other plant materials significantly reduced import/export needs and provided key microbial inoculants to stimulate the rapid establishment of native vegetation.
Based on the large effort to incorporate sustainable practices and materials into this project, CDM Smith identified it as a promising subject for an internal research and development project to test the newly released Envision sustainability rating tool for civil infrastructure. The idea was proposed to the county and the decision was made to apply Envision to the Snow Creek project based on the following objectives:
• a strong common commitment to produce a truly sustainable project;
• to build knowledge and experience in planning sustainable infrastructure projects; and
• to promote sustainability planning with tools such as Envision and share the experience in planning a sustainable infrastructure project
The Envision tool
Envision uses five categories and 14 subcategories to provide a holistic sustainability assessment of infrastructure projects over their entire lifecycle. Under each category, innovation points can also be earned for both exceptional performance and innovative approaches in sustainable infrastructure. The five categories are:
• Quality of Life addresses a project’s impact on the health and wellbeing of individuals and the community as a whole.
• Leadership examines project-related collaboration, management, and planning activities that demonstrate effective leadership and a commitment to sustainability by the project proponents.
• Resource Allocation measures the project’s consumption or production of resources including physical materials, energy, and water.
• Natural World assesses project impacts on the surrounding habitats, species and non-living natural systems.
• Climate and Risk evaluates project related emissions that may contribute to climate-related risks and the project’s resilience to short-term hazards and altered long-term future conditions.
Credits within each subcategory provide a means of scoring the project for a wide range of sustainability indicators. For each credit, evaluation criteria help project teams assess performance and assign appropriate points. The Envision Guidance Manual provides users with all of the information necessary to perform the evaluation and a rigorous training and accreditation program ensures that individuals assessing the projects have the appropriate qualifications to lead a team in applying the rating system.
The sustainability evaluation of the project and the Envision application was completed by CDM Smith staff accredited by ISI as Envision Sustainability Professionals (ENV SP). The self-assessment checklist was used initially, then the web-based Envision tool was used to rate the project. Once the application was completed and submitted to ISI, an independent third-party verification and authentication process was conducted to review the evaluation and confirm the scoring. The results of this process showed that several important components of the project components were instrumental in earning the platinum rating.
Project sustainability performance
The project received the most points under the Natural World category due to its restoration of an industrial site to create diverse types of natural habitat, including new wetland areas. Truck traffic, noise, and air pollution were dramatically reduced and contaminated soil and construction debris have been removed. The project created buffers between developed areas and existing environmentally sensitive areas to protect SEZ habitat and water quality. Implementation of low-impact development (LID) strategies for stormwater management help to re-establish the site’s predevelopment hydrology, and treatment through the newly constructed wetland areas reduces sediment and nutrient loads to Snow Creek and Lake Tahoe.
The quality of life in the community was improved by providing a walking/biking trail that connects to existing trails, providing stable access to sensitive environmental areas and restoring natural views and local character. It creates a recreational and transportation amenity that compliments existing and planned trail infrastructure in the area and enhances public open space with improvements to safety and aesthetics.
Extensive salvaging and reuse of existing onsite resources, including topsoil, native sod and shrubs, rock, and concrete materials and the incorporation of a recycled railroad flatcar bridge, resulted in points awarded for conserving resources and reducing emissions. Trees and shrubs planted around the newly created channel will provide shading to maintain cooler water temperatures and habitat.
The application of a rigorous planning process required for many Tahoe basin environmental projects contributed to leadership points by establishing a stakeholder-based decision-making framework that included representatives from jurisdictional agencies and property owners. The process also includes a detailed existing conditions analysis and an alternatives evaluation based on a consensus-based decision-making process. The documentation produced during project planning was highly useful for the Envision application.
Benefits of using Envision
This sustainability evaluation was conducted on an ongoing basis throughout the project planning process and its benefits were quickly realized by the project team. Not only was it quickly apparent that the project would score highly, but the use of Envision triggered new ideas and design considerations that added even more value to the project. Additional opportunities were identified for reducing the amount of imported and exported materials and reusing onsite existing onsite resources.
Also, in addition to reducing project-related greenhouse gas emissions, the design was scrutinized for its resiliency to climate change-related impacts such as increased flooding and wildfire risk. The considerations included in the Leadership category resulted in the county taking a close look at its existing sustainability policies, assembling related guidance documents, and considering new approaches to advance its program.
Finally, the broad perspective Envision provides during the planning process also strongly supported the diverse goals associated with the variety of funding sources for the project. From the perspective of this project team, the Envision sustainability rating system truly does meet its stated purpose of initiating a systematic change in the way infrastructure is designed, built, and operated.
Stefan Schuster, P.E., ENV SP, is a principal water resources engineer at CDM Smith with 20 years of environmental resources and water quality experience. Kansas McGahan is a senior engineer with the Placer County Department of Public Works. Suzanne Wilkins, AICP, ENV SP, has worked as an environmental planner in California and Nevada for more than 20 years, primarily on public works projects.