Gas spill clean-up to take years
The clean-up operation following the Rubis Energy Bermuda gas spill in March is likely to take several years according to the Department of Environment and Natural Resources.
Monitoring from the four new wells in addition to the many existing wells has helped assess the damage. The spill consists of: “Liquid plume” floating on the groundwater some 70 feet below grade level; “vapour plume” of gasoline fumes above the water table within the limestone; and “dissolved plume” of more water-soluble components in the gasoline that are dissolved in the groundwater.
All plumes appear to be contained under the RUBiS site. The strategy to recover the liquid and vapour plume is well established using the six recently drilled vapour extraction recovery wells in addition to other suitably-located existing wells. Evidence points to the extraction limiting the plume to the confines of the RUBiS site.
Extraction system has been operating daily since April 1 with the exception of six days in May because of a technical problem. The recovered vapour/liquid product from these operations is about 7.6 per cent of the original volume of the spill as of 5 June.
The rate of recovery suggests that the clean-up operations will be expected to take several years, with monitoring beyond this period.
Government contracted a US consultant, John Wilson, with considerable experience of managing solvent and fuel spill clean-up operations of the ground and groundwater and who was previously employed as a technical expert in this role by the US Environmental Protection Agency (EPA).
Dr Wilson visited the RUBiS site in early May with personnel from the Pollution Control Section of the department.
A department spokesperson said: “The Trip Report from Dr Wilson to Government highlighted that ‘Based on [his] experience with the state agencies in the USA that regulate fuel spills, the response provided by DENR and by RUBiS Energy Bermuda was equivalent to the response that would have been provided by the best of the state agencies in the USA when the state agencies in the USA were acting under the best of conditions. The state agencies in the USA would have taken the same approach for risk management as was taken by the Department of the Environment and Natural Resources and by RUBiS Energy Bermuda Limited’.
“Although RUBiS Energy Bermuda initially notified the regulator 24 hours later than required, the consultant considered that the implementation of the Soil Vacuum Extraction system within five days of the spill to start the recovery operation and to help limit the spread of the spill was a ‘timely and appropriate’ response to the spill. Furthermore, monitoring all existing and newly drilled wells, including off-site private wells, on a daily basis started within two days of the spill has helped define the extent of the liquid plume, vapour plume and dissolved plume. Other cleanup and monitoring recommendations provided by Dr Wilson are currently being considered by DENR for discussion with RUBiS Energy Bermuda Ltd. Further to additional assessment by RUBiS, DENR expects an additional strategy to recover the dissolved plume from the groundwater.
“RUBiS Energy Bermuda Ltd submitted a Limited Site Assessment report (LSA) on June 2, 2017, per Government’s guidelines.
“The purpose of the LSA was to provide an assessment of the site and to characterise the risk posed to the public and the environment. This report and the subsequent Remedial Action Plan (RAP) will also be reviewed by DENR personnel and government’s consultant, Dr Wilson, to ensure that the effects of the spill remain isolated below the RUBiS site and do not affect any off-site resources such as private wells. This review by Government will continue until the spill is fully remediated.”
Monthly updates on progress will be provided to the public by the DENR.