In early 2014, complaints were received of an occasional strong odour, said to be akin to the smell of creosote, on Portslade Beach. The source of the odour was not easy to identify but eventually, small quantities of an oily substance were found to be seeping from the foreshore at extreme low water.
Our team and our environment consultants, Arcadis, the Environment Team at Brighton & Hove City Council, the Environment Agency and Public Health England worked together to determine, firstly, whether the oily substance posed any significant risk to public health or the natural environment and then to find where the oil originated from and whether the seepage could be stopped.
The investigations on health and environment risk included chemical analysis of the oily substance and air quality monitoring at nearby residential properties. Public Health England concluded that there was ‘nothing in the results provided to suggest a cause for public health concern’.
The conclusions of the investigations and Shoreham Port’s intentions on future investigations were set out in a letter from Brighton & Hove City Council to local residents:
BHCC Letter to Residents dated 30th October 2015
The Next Steps: Where did the oil come from and could it be removed?
Chemical analysis of the oily substance showed it to have a composition characteristic of the by-products of coal gas production and this established beyond reasonable doubt that the oil originated from the buried remains of the old Portslade Coal Gas Works that occupied 22 acres of land now forming part of the port immediately north of the foreshore where the seepage occurred.
We are determined to take every reasonable action within our powers to alleviate or remove the nuisance caused by the oil seepage. Therefore, the next steps proposed were intended to undertake all practical investigations and analyses that could help to identify:
- Any concentrated sources of the oil underneath the old gas works site where the oil could be extracted;
- The pathways that the oil was taking to the foreshore;
- Why and how was the oil seeping out at one particular spot?
The results of the investigations and analyses by our environmental consultants, Arcadis, are set out in the Non-technical Summary to their report here.
Setting the Way Forward: Action to reduce future risk
There are two main ways in which we can help to reduce the risk of a recurrence of the seepage issue:
1) Beach Recharge
Our investigations indicated that a major factor leading to the seepage on the foreshore was the lowering of foreshore sand levels by storm action in the winter of 2013/14. Lowered beach levels caused problems for coast protection all along the south coast, of course, but on Portslade Beach it exposed a layer of mudstone, or stiff clay, that the oil was seeping along. Had foreshore levels remained higher, the oil would not have been exposed and the odour nuisance would not have occurred.
The foreshore is a highly dynamic natural environment and the Port cannot prevent future storm events, of course. However, we can have some positive influence on beach levels by importing beach material to replace that lost through littoral drift and extreme storm events. We have recharged the beach further to the west at Southwick and some of the sand placed there has drifted along the foreshore to Portslade and helped to bury the exposed mudstone.
We will continue to do all we can to maintain foreshore levels. Working with the local authorities and the Environment Agency we carry out significant shingle recycling operations twice a year and, where possible, seek to improve foreshore levels by depositing shingle at strategic locations along our frontage.
2) Removal of Oil
Our investigations indicate that there is no practical way of removing all of the oil that may remain underneath the old gas works and, indeed, that attempts to do so could make the situation worse. However, we are removing consistent amounts of oil from a specially sealed borehole within our operational site to prevent it migrating towards the foreshore. By September 2019 we had extracted over 135 litres of oil and the equipment is regularly maintained and adjusted to optimise this process. We continue to carry out monthly ‘routine’ monitoring visits, quarterly ‘in-depth’ investigations and annual multi-agency reviews with our partners at Brighton & Hove City Council and the Environment Agency. Guided by the results of this, and with our specialist consultants, we remain committed to reducing and mitigating the risk of further seepage.
We will continue to post updates on our website whenever there are significant matters to report.
Updated March 2021