Improvements in the Design and Application of Erosion and Sediment Control Technologies for the Construction Industry

Abstract

Erosion and sediment controls (ESCs) have become essential components of construction related activities. Stormwater pollution prevention regulations are the principal catalysts driving the development of new ESC practices and products to ensure regulatory compliance for the construction industry. Federal, state, and local environmental protection regulations require construction generated pollution to be controlled on-site prior to discharge to avoid impairment of receiving waterbodies. Regulations include provisions on the design, implementation, inspection and maintenance, of ESC practices.

This dissertation explores improvements made in the design and application of ESC technologies through the development of a sediment basin design tool, large-scale testing of sediment basin practices, the use of unmanned aerial vehicles for inspection purposes, and the transfer of innovative ESC technology to the construction industry.

Sediment basins are stormwater detention practices commonly used to capture and treat sediment-laden runoff prior to discharging from a construction site. However design and implementation of basins in the field often deviate significantly from regulatory design guidance. A spreadsheet based tool, SEDspread, was developed to provide designers a user-friendly platform to assist in the sediment basin design process. The tool provides designers the ability to implement hydrologic based designs to allow for appropriately sized and configured sediment basins on construction sites based upon the regionally specific design criteria [i.e., 1,800 or 3,600 ft3/ac (125 or 250 m3/ha) volume sizing factor, 2-yr, 24-hr rainfall event, or manual input].

Further research is necessary to understand sediment basin performance under various design conditions using large-scale testing techniques. This dissertation details the design, construction, methodology, and testing performed on a 2,790 ft3 (79.0m3), large-scale sediment basin at the Auburn University - Erosion and Sediment Control Testing Facility (AU-ESCTF). Testing was performed on various sediment basin design configurations and high-rate lamella plate settler technology within the basin. Data collection efforts included: water quality, flow rates, basin stage levels, sediment deposition volumes, and sediment sampling for particle characterization. Data was used to evaluate the performance of various basin design configurations.

Testing results indicated that the use of an excavated sump in the forebay of the sediment basin inflow channel and the use of a modified first baffle system provided no improvements to the performance of the basin. Testing did show that high-rate lamella settlers oriented in upward and parallel configurations were 18.2% and 29.0% more effective at reducing turbidity between Bay 1 and Bay 4 when compared to the Alabama Department of Transportation (ALDOT) standard configuration, respectively.

Remote sensing with unmanned aerial vehicles (UAVs) has the potential to provide high quality aerial imagery and data that can assist Qualified Credential Inspectors (QCIs) in performing focused, strategic site inspections in an efficient and effective manner. Research performed on an active construction site showed that UAVs have the potential to assist inspectors in performing thorough site inspections efficiently and more strategically. By providing a complete aerial view of the site at the onset of an inspection, the inspector has the ability to quickly identify problem areas, discharge points of concern, and determine whether further detailed investigations are warranted. Furthermore, photogrammetric techniques were used to provide analyses on the collected aerial data through the creation of digital elevation models (DEMs).

Through the results of recent AU-ESCTF research efforts, ESC designs are transitioning towards hydraulic and hydrologic based designs to better cater to site parameters and improve the performance of practices. While educational and research resources for ESC designs have increased in availability, a need still exists to fill the gaps between the knowledge base developed through research and the needs of practitioners. The ESC Technology Transfer programs developed and disseminated at the AU-ESCTF provide the platform to distribute knowledge, practice, and techniques with industry professionals. The AU-ESCTF has provided several successful training opportunities geared at specific target audiences within the ESC industry.