Every molecule of water in the ocean was once a raindrop falling on a mountain peak somewhere and every drop of rain that falls on a construction site today will soon end up in our groundwater and eventually, back in the ocean. What does this mean for construction planners and workers?
It means that every day of work is an opportunity to contribute to or endanger, depending on our choices, the health of aquifers like rivers, wetlands, and lakes, that provide us with so many ecosystem services. These services include swimming, fishing, slope stabilization, flood mitigation, and, of course, the natural filtration that provides clean drinking water to millions.
Point and Non-Point Water Pollution
Since the passage of the Clean Water Act in 1972, acceptance of rules against point pollution, or polluting waterways by dumping large amounts of pollutants from a single source, has become widespread in American culture, including the construction sector. However, people are less familiar with more recently developed rules against non-point pollution which, as the name suggests, results when small amounts of pollution from multiple sources combine to negatively affect water quality.
This is the danger of unimpeded erosion from construction sites, even if toxic materials are properly covered and waste disposed of safely, the disturbed soil can be easily blown away or washed downstream. This creates an imbalance of nutrients in aquatic ecosystems which can result in algae blooms and fish die-offs.
Erosion Means Topsoil Loss
Because disturbed soil on construction sites is many times more vulnerable to erosion than agricultural land, site managers have a great opportunity to help preserve local topsoil. Our ability to grow enough food depends on this thin layer of organic matter, plant nutrients, and communities of microorganisms, and it’s currently diminishing faster than it can be built back up. This, in turn, causes decreased crop yields as well as a higher susceptibility to drought and disease.
While farmers and crop scientists work towards reducing agricultural land erosion, construction site managers can have a large impact on the problem, when considered on a per-acre basis. In the process, by preventing erosion from the wind, as well as rain events, they can also improve local air quality.
Erosion Prevention Techniques
There are many ways construction workers and managers together with architects, planners, and any other interested parties, can prevent erosion, water pollution, and topsoil loss at work sites. The most effective ecologically-sound methods for erosion control involve slowing the movement of water over the disturbed soil with biodegradable materials which also prepare and seed the area with vegetation that will anchor the soil and filter runoff.
Correctly laid organic mulch can retain moisture, encourage aeration of the soil, add nutrients, and inhibit weed growth while encouraging desired seed germination. Synthetic mulches are more often used for decoration and slope stabilization than for ecological restoration.
Erosion Control Blankets
When sudden rainfall events or strong winds might prove too much for a layer of mulch an erosion control blanket is recommended. Made of biodegradable materials, anchored to the ground with pins, staples, wattles, or live stakes, and coarsely woven to allow seed germination, they can provide even greater slope stabilization, reduce evaporation, and even protect seedlings from hungry wildlife.
These tube-shaped structures often made of straw (they are also called "logs") can be used alone or in conjunction with other erosion control products to create temporary terraces or be used as a biodegradable alternative to silt fences. They are versatile and effective in filtration, moisture retention, and encouraging vegetation growth.
These are glue-like substances that provide long-term dust control, water absorbance, and as anchoring for mulch, whether synthetic or organic. The organic tackifiers, based on guar or psyllium, also encourage germination and help build topsoil.
Erosion Control is Part of Permitting
Generally speaking, most sites or projects of more than one acre in size will require a Stormwater Pollution Prevention Plan (SWPPP) in order to be permitted. These permits may be issued by the EPA or a state agency. Fortunately, the EPA provides many resources, including SWPPP templates and a permitting flowchart.
Because non-point pollution and topsoil depletion are widespread, every small action taken to prevent erosion has a meaningful, positive effect on water, soil, and air quality. It's a daily opportunity that every company should embrace.