Low-impact development (LID) has emerged as a highly effective and attractive approach to controlling stormwater pollution. By emphasizing cost-effective, site-level strategies, LID principles and practices manage stormwater in a way that reduces the impact of built areas and promotes the natural movement of water within an ecosystem or watershed. On a large scale, LID contributes to the maintenance or restoration of a watershed's hydrologic and ecological functions.
LID employs several principles, such as preserving and recreating natural landscape features, and minimizing impervious surfaces to create functional and appealing site drainage. LID has been used in a wide variety of ways, including bioretention facilities, rain gardens, vegetated rooftops, rain barrels, and permeable pavements.
NDS, Inc. recently introduced a stormwater management solution that is a new approach to LID. The NDS S5 Sustainable Stormwater System manages stormwater as close to its source as possible through runoff reduction and quality enhancement at the site scale. The S5 system is highly flexible and scalable, and utilizes a variety of NDS components, such as catch basins, channel drains, and dry wells. Ideal for working with the contours and features of any site, S5 can be configured to meet a wide variety of residential and commercial applications. It is engineered for high performance while meeting today's regulations for onsite stormwater management.
The S5 system delivers five key sustainable benefits:
- conserves stormwater onsite through filtration, detention, and infiltration to counter the effects of drought, pollution, and storms that threaten the quality and quantity of clean water;
- manages rainfall onsite by maintaining pre-development hydrology as closely as possible and reducing downstream impact by using smaller, decentralized controls for filtration, detention, and infiltration;
- empowers designers to adapt the system footprint to the specific environmental conditions of an application site;
- filters debris and other suspended solids, preventing negative downstream impacts through detention and infiltration components that reduce peak overflows; and
- promotes subsurface recharge to balance groundwater withdrawal.
Two projects that provide good examples of how the S5 system can be configured are a corporate campus installation of fire lanes and a professional sports team installation of a drainfield for its athletic field.
Fire lane on a corporate campus
When Dell announced plans to build a high-profile campus for more than 1,000 employees, regulations called for dual fire access roads. As a company committed to environmental sustainability, Dell chose NDS EZ Roll Grass Pavers for its fire lanes as an alternative to traditional paving methods.
The flexible, plastic paver mats were selected for their durability and ease of installation. With cross-links connecting the flexible rows of nested cells, the product ships in 600-square-foot rolls and can be rolled out on the jobsite. By protecting the root zone and preventing soil compaction, the pavers also allow healthy grass to thrive in areas that would traditionally have impervious hardscaping installed. The EZ Roll Grass Pavers are manufactured from 100 percent recycled material.
Since the initial installation, Dell has committed to becoming the "greenest" technology company on the planet. Today, Dell powers its Oklahoma City Campus with 100 percent wind energy, and the grass on the fire lane access roads is green and thriving.
Drainfield for athletic field
When the Clarington Tiger-Cats, a minor league professional football team in Ontario, Canada, began planning construction of a new athletic field, landscape architects needed to identify a drainage approach that would work for a space that was heavily and continuously used.
A tile drain would typically be specified for this type of project, but tile drains have an inherent challenge — to install this type of drain, gravel must be delivered, stockpiled, and moved around the construction site, which is not ideal for a playing surface because of extensive subgrade compaction. It also requires a high level of labor and heavy equipment costs. Landscape architects also considered using a vertical strip drain system, but this method requires a significant amount of sand backfill, which has differential settlement issues. This would entail future maintenance costs, which were a key concern for project planners.
An NDS EZflow Drainage System was selected because it requires no gravel. It consists of three or four slotted corrugated pipes surrounded by NDS poly-rock, a lightweight gravel substitute, all wrapped in a geotextile fabric. By eliminating the need to transport, shovel, and move heavy gravel, it cuts installation time in half, and is durable, crush-proof, and has a lifespan of 100 years. The EZflow system is designed to take water out of the soil and pipe it to a safe discharge point.
EZflow can be covered with native soil instead of sand. Native soil will recuperate faster than sand, and it can take more of a beating from heavy use. Also, EZflow allows the reduction of slope around the field, making it easier for people to view the action on the field.
For the Tiger-Cats' project, landscape architects leveled the subgrade 1 degree, then excavated 12-inch-deep, 16-inch-wide trenches in a herringbone pattern. The EZflow pipe was then placed in the trench, covered with geotextile paper, and then topped with screened native topsoil. Approximately 5,200 linear feet of EZflow was installed, and project planners estimated an overall cost savings of 25 percent compared with traditional gravel and pipe. One measure of the project's success is how well it handles the freeze/thaw cycle in Canada. The product has performed well and there have been no settlement issues.
Ryan Larsen, a civil engineer at NDS, Inc. (ndspro.com), has nearly a decade of experience in civil engineering, land development, and the building materials and construction industry, and is an authority on issues and solutions related to drainage for homeowners and businesses. He is also known as "Dr. Drainage" as host of NDS's educational YouTube video series on drainage systems and stormwater management.