By John Summerlin—Lead Compliance Manager // 2023-01-05
Due to the mass movement of earth in construction processes, erosion prevention and mitigation remains a constant variable in building operations. Soil erosion is defined as, “…the wearing away of land by the action of wind, water, or gravity or a combination of wind, water, and gravity” (Taylor). All of these factors may play a role in the potential deposition of sediment, which when applied to natural water resources, can detrimentally affect life in riparian areas. In order to limit sediment runoff from construction sites, the primary types of erosion operators must be aware of and include the following: splash erosion, sheet erosion, rill erosion, and gull erosion.
Splash erosion is the first stage in the erosive process. This type of erosion results from the bombardment of rain drops on surface soil. Once the rainfall has dislodged enough sediment, the loose soil particles then have the potential to move downslope via sheet-flooding. If the bare sediment present in the given area is not stabilized within an adequate time-frame, erosive channels will continue to form which increases the risk of sedimentation. Assuming the erosion in question goes unaddressed, the next steps include rill and gully erosion. Rill erosion forms as the channels continue to deepen; rills can be as deep as one foot. Once the channels exceed that depth, gully erosion has formed on the project site.
Due to the relatively predictable nature of weather patterns, it is possible to prevent and/or mitigate soil’s erosive potential. The most effective method of erosion prevention is the presence of adequate vegetation. Multiple studies have shown that ground cover must be maintained at levels above 70% to prevent the detachment of soil particles. With that being said, the establishment of vegetation is not always practical on a construction site, whether it be due to the current phase of construction operations or the time of the year (climate depending). Velocity dissipators such as surface roughening and rip-rap can be installed as mitigative measures that prevent sediment runoff. Additionally, the implementation of BMP’s such as erosion control blankets can be used to prevent erosion from exposed soils. These blankets are typically composed of organic fibers held together by synthetic or biodegradable netting, which act as an artificial vegetative cover. Applying these practices to construction sites can significantly reduce sediment runoff and maintain the biodiversity within natural waterways adjacent to potential construction sites.
Should the aforementioned BMP’s not be installed on a project site, the operators risk the potential of erosion that could lead to reduced soil quality and/or water pollution. Due to mass earth moving across the nation, sediment has been listed as the top pollutant in our country’s natural waterways. The personnel at Earthworks Environmental will continue with the goal of inspections not only to mitigate sediment runoff, but to prevent erosion where possible. By employing this objective, our staff aims to not only keep our clients in compliance, but also to preserve aquatic life and the areas in which humans and wildlife alike depend on.
References
Taylor. “Erosion Control on Construction Sites.” Superior Groundcover, 27 Apr. 2022, https://www.superiorgroundcover.com/erosion-control-on-construction-sites/#:~:text=Soil%20erosion%20happens%20when%20construction,both%20wind%20and%20water%20erosion.
“Department of Natural Resources and Environment.” Splash Erosion (Rain Drop Impact) | Department of Natural Resources and Environment, https://nre.tas.gov.au/agriculture/land-management-and-soils/soil-management/soil-erosion/soil-erosion-types/water-erosion/splash-erosion.
