Reliability of Technical Measures for Erosion and Sediment Control in Construction Worksites

Abstract This study investigates reliability engineering approaches to structure the assessments of the reliability of erosion and sediment controls for two culvert replacement projects. Construction projects require that a System of Erosion and Sediment Controls (SESC) meet water quality guidelines through monitoring activities that seldom addresses the reliability of the system. The reliability analysis uses the maximum increase of 8 Nephelometric Turbidity Units (NTU) from background levels ( ∆Tu ) for a short-term exposure (< 24 h) from the Canadian Water Quality Guidelines for Total Particulate Matter. The analyses are conducted for the early, stable, and wear-out reliability periods with the addition of catastrophic periods. A reliable SESC is expected to perform its intended function during the stable periods. Aligned with reliability engineering theory, the rates of exceedance for the stable periods of each project are the lowest when compared to the other reliability periods (i.e., 0.026 and 0.027 ∆Tu > 8 NTU event per hour). In addition, the average amount of time ∆Tu ≤ 8 NTU for the stable periods is the longest compared to the other reliability periods (i.e., 33.6 h and 34.0 h). As well, the average amount of time when ∆Tu > 8 NTU are 2.1 h and 1.6 h for the stable periods. The SESC did not fail the requirements of the guideline during stable periods because we did not observe ∆Tu > 8 NTU for more than 24 h. We also discuss the importance of contingency response plans to deal with stochastic environmental events.