Biological optimization of hydraulic cleaning of oiled coarse-sediment beaches: Preliminary results

Abstract

This document summarizes the findings of a pilot study that was designed to determine biologically optimum cleaning parameters. The objectives of this ongoing study are (1) to determine the biological effects on intertidal biota associated with the use of hydraulic cleaning techniques, and (2) to develop data on environmentally optimum combinations of hydraulic cleaning parameters for use by oil spill responders. The laboratory/pilot scale phase of the project was conducted at the Bamfield Marine Station on Barkley Sound, British Columbia, in the fall of 1995. The hydraulic cleaning parameters examined were (1) water pressures ranging from deluge or minimal pressure to approximately 345 kPa (50 psi), (2) water temperatures ranging from ambient temperature to 80°C, and (3) nozzle angles of 45 degrees and 90 degrees to the substratum. Both oiled and unoiled trials were conducted. Treatment combinations of these parameters were delivered using a pressure washer connected to a constructed washing apparatus. The biological effects produced by the treatments were examined in attached organisms colonizing cobbles collected from a donor beach in Barkley Sound. Species tested included the algae Fucus spp. and Mastocarpus papillatus; the barnacles Chthamalus dalli and Balanus glandula; and limpets in the family Lottiidae. Among the main findings of the laboratory/pilot study were the following: (1) both mortalities and oil removal efficiencies were found to rise most rapidly from low to high levels between 40° and 60°C, and between 18.6 and 60 kPa (2.7 and 8.7 psi); (2) oiled trials were found to produce greater mortalities than unoiled trials; and (3) 90-degree nozzle angles were found to produce greater mortalities in some cases than 45-degree nozzle angles.