As the challenges facing municipalities continue to stack up, it has become our task as engineers to deliver projects that can produce multiple benefits at once. Where do we find inspiration for these groundbreaking solutions? Often these innovative ideas come directly from the world’s original engineer—Mother Nature. Flood mitigation, stormwater pollution, water conservation, and other pressing problems can often be reduced when we weave elements of nature’s original design such as restored wetlands, riparian buffers, or infiltration areas into our projects.
The power behind nature-based solutions is driving the UN’s theme for World Water Day this year— “Nature for Water.” In honor of this global celebration, I wanted to share some of the ways Woodard & Curran is using nature-based designs to deliver multi-beneficial projects for our clients. Although as a firm, we are using nature-based solutions in many unique ways across the country, I will center this article around the projects I am most intimately involved with: stormwater in California.
Nature’s Influence on Stormwater Issues
Stormwater projects benefit from nature-based designs in two major ways: conserving water supplies and protecting downstream water quality. In California’s drought-prone urban areas, stormwater is often not fully utilized because of the non-porous surfaces that dominate the landscape. Without stormwater controls, this valuable water runs off into local water bodies, often carrying with it excess nutrients and other pollutants. Downstream water bodies are often impaired by stormwater either through direct nutrient pollution or through erosion during wet weather events. Mimicking nature’s naturally porous surface and working with our natural topography can help harness stormwater and filter out impurities.
Low Impact Development
Low impact development (LID) mimics a site’s original hydrology, using design techniques that infiltrate, filter, store, evaporate, and detain runoff close to its source. This is ideal because it allows projects to utilize the water on site with minimal construction costs. We developed standards and conceptual designs for the integration of LID techniques into various streetscapes throughout the City of San Francisco. These multi-beneficial projects work with a site’s watershed characteristics to reduce the volumes and peak flows of stormwater entering the combined sewer system and alleviate localized flooding, while also contributing to neighborhood greening and ecological function and increasing the beauty and safety of the pedestrian realm.
Harvesting and Using Stormwater Onsite
Projects can take a more aggressive approach to conserving water on site through stormwater storage. Again, this process mimics the natural systems by storing and using stormwater near its source. We helped the City of San Francisco develop a Citywide Stormwater Storage Opportunities Review to evaluate the potential volume of stormwater storage that could be constructed within the city as part of parks, schools, designated redevelopment areas, and other buildings. We took this concept a step further in the City of Malibu where we designed one of the first projects that combines a vegetated detention pond with a stormwater treatment facility to store and use rainwater and urban runoff.
Flood protection projects traditionally meant widening creeks on both sides, digging an “efficient channel shape,” straightening out the curves in the creek, eliminating maintenance issues (such as trees), and possibly even paving the creek with concrete. Today we understand that using techniques that work with the channel’s natural hydrogeological shape allows us to achieve the same results in a more ecological manner. We applied a modern geomorphologic analysis to the Upper Llagas Creek in Santa Clara Country to determine the channel shape that would provide a more stable waterway and not be prone to incising or depositing sediment.
Harnessing some of the moves from Mother Nature’s playbook can help projects achieve multiple benefits, often with shorter construction times and reduced construction costs. However, for these projects to be truly successful they need to be coupled with adequate construction and maintenance education as they often require specific construction techniques and additional upkeep that need to be properly addressed.