Theoretical comparison of cumulative sound exposure estimates from jacket and tripod foundation construction

Foundation pile driving during offshore construction has led to increasing concerns regarding radiated noise and its effects on the marine fauna (receptors). In the case of many static offshore developments two commonly used foundation techniques are tripod-constructions involving installation of a series of smaller diameter piles surrounding a central structure and mono-piles using a single larger diameter pile. Pile installation itself may involve sequences of percussive piling at different hammer energies, vibro-piling (more rapid, lower level vibrations) and drilling. In some cases all three techniques are used on a single pile installation. The spectral characteristics, as well as duration and level of the total radiated energy from these techniques can vary significantly and may result in different Sound Exposure Levels (SEL) experienced by marine fauna. This paper theoretically explores the potential difference in total SEL for various receptor scenarios for each of these techniques using available source characteristics data. The total sound SEL’s for each scenario are compared and model sensitivities identified.