Site contamination and history
Overview
Land contamination and remediation is one of the matters considered as part of the scheme design and regulatory approval process.
This page is intended to introduce the context of the site in relation to land contamination, explain the framework that will consider it and the steps we are taking to address this.
History of the site
The site was historically part of a gasworks site used in the manufacture and storage of town gas from coal, a common process prior to the introduction of natural gas. An archive aerial photograph illustrating the site area is shown above.
Gas manufacture involves the distillation of coal into its constituent parts (e.g flammable gas, ammonia rich water, tar/oils and coke) resulting in residues associated with production, washing, purification and storage.
An overview of the gas manufacture development history and processes is provided in the linked guidance developed by CL:AIRE.
Contamination
The by-products of gas manufacture had onward commercial value, including the production of fertilizers and chemicals, but some of these may have entered the ground beneath the site where they remain to the present day.
Typical gas manufacture ‘contaminants’ include various types of hydrocarbons and soluble compounds and gas purification residues (including inorganic compounds and metals). The infrastructure associated with production may also present a potential source of contamination and it is noted that the site was damaged by bombing during WWII.
The historic processes that occurred on the site have been established through the review of historical maps and archives and are visually illustrated in the historic site plan on the right hand side. A detailed summary of the processes that occurred at the site is presented in historical National Grid Archive information.
Most of the gas manufacture process occurred to the north and west of the site and this previously extended across what is now Salter Road and Brunel Road all the way to the River Thames.
The northern portion of the site was peripherally occupied by ‘purifiers’; ‘washers’; and, several storage tanks (for water and production residues).
The remainder of the site was largely occupied by 4 [storage] gasholders (and their associated ‘tanks’), ancillary processes and coke loading yard / hoppers / fitters. It is noted that some of the gasholders were re-built and repurposed over time.
Historic site plan
Consideration of land contamination during development
Over 4,000 gasworks were built in Great Britain, which have left a considerable environmental legacy. These have been progressively re-developed, following the decline of gas manufacture, into a wide range of uses, most commonly under the planning system, as proposed in this case.
The remainder of the former Rotherhithe gasworks has already been developed. This includes southern part of the former gasworks site encompassing the eastern side of Kinburn Street.
Planning guidance at a national and local level establishes the principles for the redevelopment of land affected by contamination. Responsibility for securing safe development rests with the developer and the local planning authority should be satisfied that the proposed development will be appropriate for its location and not pose an unacceptable risk.
In order to consider land contamination, a staged process of assessment will be undertaken that will encompass ground investigation, risk assessment, options appraisals, remediation implementation and verification (overseen by appropriate planning conditions). Further guidance on these topics can be found on land contamination risk management and CL:AIRE Water and Land Library (WALL) websites.
At present the assessment process is in its early stages. A Desk Study has been prepared and this incorporates the results of historic ground investigation information that has been provided by the current owners of the site [SGN] and Southwark Council.
A qualitative risk assessment has been completed that indicates there is a risk associated with potential land contamination and consequently a detailed investigation, risk assessment and remediation process will be required to make the development safe for the future users and the neighbouring residents.
Remediation
The preferred remediation option will be selected in view of a wide range of technical, regulatory, practical and commercial objectives but it is recognised that the option selected must be acceptable to relevant stakeholders including, the regulator, developer and other interested parties such as local residents. The intent is to engage with stakeholders at each stage of the process and explain the approach as it develops.
One of the key remedial objectives will be impacts of the remediation on people and the environment during the construction phase, notably air quality (emissions, dust, odours and vapours), noise and vibration. The Remediation Strategy will state how it will protect human health, the environment, ecology and other receptors and will include the details of how the works will be arranged, controlled, monitored and reported. The remediation will not proceed until relevant regulatory approvals are in place.
Images credit: National Archive.