Kellie McNamara of RPS Belfast describes the proposed remedial measures and
regeneration programme for Belfast's vast Titanic Quarter site.
Belfast's Titanic Quarter is a 75ha brownfield site of largely cleared land located at Queens Island within the Belfast Harbour Estate, close to Belfast city centre. The site was once part of the Harland and Wolff (H&W) shipyard which in the height of its success employed over 30,000 people and was one of the main economic drivers of Belfast's growth and wealth during the early and mid-1900s.
RPS, as one of Ireland's leading multi-disciplinary consultancies, has a solid reputation which helped to ensure the company was engaged by Titanic Quarter Ltd to provide advice and support on contaminated land issues, including planning, remediation and development aspects.
RPS sought to recognise the vision that the developer, Harcourt Developments, had for the site. This vision was to create a high profile European waterfront development, firmly rooted in the history and character of Belfast, acting as a driver for high quality investment and development in the city.
The new urban quarter will consist of a number of residential neighbourhoods, a high quality business environment, retail, leisure and local services opportunities, along with a major tourist attraction in the form of the Titanic Signature Project. The development will ultimately create thousands of new jobs and bring a new dynamic to an area of the city that is currently run down, under used and badly in need of regeneration.
RPS's initial phase 1 evaluation has included:
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assessment of environmental issues and liabilities based on existing information
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planning procurement and management of site investigations to examine specific site issues
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Quantitative Risk Assessments
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assessment of remediation options and costs associated with the management of identified environmental liabilities
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discussions with the Northern Ireland Environment Agency regarding remedial proposals and waste management licensing exemptions.
Sampling
In 2005 the buildings and above ground infrastructure of the shipyard works were demolished and the surface was left mantled by the concrete floor slabs and internal roadways, encompassing 21ha within the Titanic Quarter and Abercorn Basin area.
Following an intrusive site investigation incorporating trial pits, window sampling and shell and auger bore holes, soil and groundwater samples were collected for geochemical testing and were forwarded to an UKAS-accredited laboratory for analysis for numerous contaminants such as volatile organic compounds, total petroleum hydrocarbons (TPHs), metals/inorganics, polyaromatic hydrocarbons and polychlorinated biphenyls, among others.
The main technical issue associated with the field works was the close proximity of the River Lagan to the site. All test locations were subject to tidal effects and saline intrusion. This was dealt with through a detailed and carefully controlled groundwater monitoring programme. The laboratory analysis and subsequent risk assessment identified metals to be the main contaminants of concern, in particular arsenic and lead, with some localised TPHs.
Source contamination
Upon characterisation of the source, it was determined that the maximum concentrations of arsenic and lead originated within the made ground/clinker ash/brick below the concrete slabs. It is not clear whether these contaminants were present in the fill material or whether they arose directly from the shipbuilding activities, such as pickling of sheet steel to facilitate oxide removal or painting of anti-corrosives and anti-fouling agents.
Stabilisation treatment
Following an assessment of a range of remedial options, including soil washing, it was determined that the most effective and efficient solution to be applied at this site would be that of soil stabilisation/solidification. Stabilisation describes a chemical change (or changes) to the hazardous constituents in a waste by means of mixing with binding agents and reactive media, which converts the contaminants into a less soluble, mobile and toxic form.
The treatment regime involves processing the material into a uniform size followed by mixing multiple binding agents and reagents into the contaminated media, such as cement, lime, fly ash, slag or gypsum, which effectively lock in the individual contaminants. The soils then undergo leachability testing prior to re-use or disposal.
The treatment alone offers a significant reduction in disposal costs, due to reclassification of the materials, and their suitability for disposal at local licensed landfill facilities. It is proposed that in addition to remediating the contaminated soils the treated material can be turned into a beneficial product with specified engineering properties for re-use on site.
This reduces the need for waste disposal and the requirement for importation of virgin aggregates that would otherwise be required during the development of the project.
The remedial programme has yet to begin but soil stabilisation trials of the materials to be treated on the site have produced positive results, supporting the proposed approach. It is hoped that works will begin in the next six months.
Kellie McNamara, Senior Scientist, RPS
