Annual Report

South Ayrshire Council

Contaminated Land

2007 - 2008

Contents

1Introduction

2Murray Gardens, Maybole

3Annbank Road, Mossblown - Ground Investigation

4Heathfield/Prestwick Desk Studies

5Reconnaissance and Reprioritisation

6Helenton - Water Sampling

7Muir Burn, Mossblown - Water Sampling

8Drumellan Street, Maybole – Ground Investigation

9Firth Terrace, Girvan – Ground Investigation

10Miscellaneous

112008 – 2009 Key Activites

1

1Introduction

This report summarises the progress made during 2007 – 2008 by the South Ayrshire Council in the area of contaminated land assessment and regeneration and provides an indication of the intentions for progress in 2008 - 2009.

Over the year SAC have performed delivered measurable progress against the Council’s Strategy for Contaminated Land and achieve best value by effective deployment of skills and resources.

Remediation works at MurrayGardens (Maybole) have moved substantially forward and this progress has been achieved through the collaboration of SAC, Jacobs, site owners and specialist remediation contractors. The remedial solution has been innovative and provides a fine example of an economic and environmentally sustainable approach to a contaminated land issue.

In addition a further 6 locations from the Council’s database of land have begun voluntary remediation and the first steps have been taken in the investigation of10 locations,in the form of detailed desk studies and physical inspections.

Going forward, we hope to substantially complete the remediation at MurrayGardens this year and depending on available funding, to further develop the understanding of high priority locations with a view to future Voluntary Remediation or determination. As outlined in CLR11 (Model Procedures for the management of Land Contamination), the approach to investigation of this land is phased such that the results of each investigation inform the design and detail of subsequent stages. In this way staff and financial resources are directed effectively and efficiently, and effort is focussed on the factors of greatest concern.

Each of the key projects are described in more detail below

2MurrayGardens, Maybole

2.1Objectives 2007 - 2008

Following the evaluation of the site and the additional data collected, remedial measures were designed to mitigate the potential risks posed to human health, livestock and the environment. Specific information was required to aid the designof remediation works. Thus, the objectives of the investigation targeted to achieve this were to:

  • Confirm the presence and depth of landfill materials in the north of the site;
  • Investigate the extent of hydrocarbon contamination from a diesel tank and to determine the composition of soil mounds in the central portion of the site;
  • Delineate the extent of the waste mass and to determine the depth of clean soil cover within a field in the south of the site, and;
  • Further investigate the risk to the factory workers from gas and to determine whether remedial or precautionary measures would be necessary.

A number of intact pollutant linkages were identified at the site and remedial measures were required as follows:

  • Installation of gas protection measures within the site to protect off site residents to the west of the site and to reduce risks posed by gas migrating towards the SAS building from the south.
  • Further monitoring of gas levels within the SAS factory building in order to determine if the buildings occupants are at risk.
  • Erection of a stock fence to prevent livestock directly ingesting leachate impacted surface water in a land drain in the south of the site.
  • Hand-picking of asbestos cladding fragments at the site surface in the central area of the site.
  • Further consideration by SAC of the status of a fuel tank, asbestos cladding on buildings and fly-tipped materials in the central area of the site.
  • Further investigation of groundwater and surface water quality of the site and its environs.

2.2Progress 2007 - 2008

Ground Investigation Works

The ground investigations were undertaken during the period 27th November 2007 to 7th December 2007 with Ritchies Ltd appointed as the drilling contractor. The investigation works were split into three areas

  • Northern Area (Ladywell Stadium and skate park)
  • Central Area (diesel tank and soil mounds)
  • Southern Area (agricultural field)

Across the three areas a range of boreholes, trial trenches and pits were done and chemical data was collected.

We also undertook surface water sampling which comprised:

  • Sampling of surface water from the Abbeymill Burn, from the unnamed watercourse on the eastern site boundary and from the drainage channel in the southern field.
  • In-situ water quality measurements including pH, electrical conductivity, redox potential, temperature and dissolved oxygen
  • Chemical analysis of samples obtained from all location for a range of contaminants

Subsequent to the completion of the site works the chemical results were collated and the risks were assessed for the receptors at risk within each of the three areas. This entailed a detailed qualitative risk assessment for the users of the Ladywell Stadium in the north, a generic assessment of the risks posed to the livestock within the southern field, and an assessment of the risks posed to onsite and off site receptors from gas migration across the whole of the site. In addition, the additional environmental risks present within the central portion of the site were reviewed and discussed with some actions proposed.

Monitoring Works and Remedial Works

Remedial Works – Gas Protection

Following receipt of information from the ground investigation works the remedial design was completed with the works commencing on 13th February 2008.

The remedial solution selected to protect receptors from the migration of gases at the site was the ‘virtual curtain’ system. This was chosen as it was capable of protecting the site users, was cost effective and allowed protection to be installed even in and around the developed areas of the site.

The‘virtual curtain’ system is a gas interception barrier that uses ventilation in installed ground ‘nodes’ to form a preferential pathway for gas to be collected and diluted at the surface. These nodes were installed at 3m centres to 3.5mbgl and comprised geocomposite strips, which were connected to a ventilation/dilution duct running along the top of the strips. The duct was also wrapped in geotextile material which has a high flow of fresh air through it by means of passive ventilation. This design allows gas emissions to be diluted, creates a zone of influence around the node enhancing gas flow towards the vents and provides a preferential pathway for gas to migrate to the surface.

The works at the site were divided into two phases with Phase 1 of the works being carried out within the northern and central portion of the site and Phase 2 of the works undertaken within the southern agricultural field.

Phase 1 of the works comprised the installation of a 188m long ‘virtual curtain’ barrier along the western boundary in the north of the site. Due to access restrictions within the central portion of the site, a barrier could not be installed and as an alternative, nine discreet ‘nodes’ were inserted in order to provide preferential pathways for gas migration.

Phase 2 of the works comprised the installation of a 305m long virtual curtain system along the western and northern boundaries of the southern agricultural field.

The installation works were largely completed by 14th March 2008 with some reinstatement works subsequently undertaken in May during improved weather conditions.

Remedial Works – Protection of Livestock

A stock fence consisting of wire net and a single barb with wooden posts and strainers was erected around the land drain within the southern field. The works were carried out on 31st March and 1st April 2008.

Monitoring Works

A gas monitor was installed for one week monitoring periods in each of three rooms within the factory; the Business Conference Room, a small computer room and the main open plan office. The monitor recorded gas concentrations once every hour for a period of seven days.

Monitoring results indicated that risks of gases migrating into the SAS factory building were low. As the period of monitoring was limited it was recommended that monitoring of enclosed spaces at the factory is repeated in order to confirm this conclusion.

2.3Plans for 2008 – 2009

Following the successful delivery of the program of works for 2007 – 2008, the next year is on-track for substantial further completion of the remaining remediation of the MurrayGardens site. Monitoring will continue long term to provide validation of the measures. Work for 2008 – 2009 is to include;

  • Further quarterly gas monitoring in SAS building;
  • Planting of a reedbed in the southern field;
  • Assessment of the deeper groundwater, and;
  • Consideration of remaining remedial works in the central area.

3Annbank Road, Mossblown - Ground Investigation

3.1Objective for year 2007 - 2008

A Phase 2 ground investigation was undertaken, the purpose of which was to further develop an understanding of site conditions.

3.2Progress year 2007 - 2008

Initially an investigation was undertaken during the period 12th December 2007 to 18th January 2008. This investigation consisted of boreholes, chemical analysis of soil and groundwater samples and four rounds of gas monitoring.

Subsequently, a report was produced and it stated that a risk is present in the form of the migration of gas to adjacent houses and the Sports Hall and from direct contact of site users to shallow soils. Additionally, the perched groundwater may present a risk to the deeper groundwater below the site. It was therefore recommended that these potential pollutant linkages were examined further to allow treatment where appropriate and reasonable.

3.3Plans for 2008 - 2009

To formally remediate or determine through Part IIA the Council will require definitive long term data and this year’s program will include the production of boreholes to confirm the extent of the waste and to assess gas migration. Additionally, it is intended that gas monitoring will be carried out within the Sports Hall and water samples will be taken from the culverted watercourse.

4Heathfield/Prestwick Desk Studies

4.1Objective for year 2007 - 2008

The objective of this project was to produce Contaminated Land Desk Studies at five sites within Ayr and Prestwick, which had been identified in theBusinessLand and Premises Review[1]. These sites had beenidentified as potential locations for future development. It was thought prudent by SAC’s Environmental Health team to have completed desk studies available so that possible constraints to development of the land, arising from contamination, could be known at an early stage.

4.2Progress year 2007 - 2008

Following an evaluation of the BusinessLand and Premises Review, detailed reconnaissance visitswere undertaken anda review of the geological setting, historical maps and available records within South Ayrshire Council’s Section 57 GIS Model was completed for each site. A preliminary conceptual site model (CSM) and risk assessment was created for each individual site with conclusions and recommendations provided to highlight any potential pollutant linkages of concern.

5Reconnaissance and Reprioritisation

5.1Objective for year 2007 - 2008

This year the next package of potentially contaminated locations (based on the SAC S57 prioritisation Model) was progressed, in line with the published Strategy for Inspection.

5.2Progress year 2007 - 2008

Following a detailed audit of current progress on the Top 150 locations, we identified the locations for inspection this year. Jacobs and SAC put together a site team and completed the inspection, recording and assessment of the reviews. The recommendations for further work at these locations are still in progress at the time of writing.

5.3Plans for 2008 - 2009

Completion of the 2007 – 2008 data collection and progression of the next batch of locations from the priority list will be the focus for this year.

6Helenton - Water Sampling

6.1Objective for year 2007 - 2008

The objective of the monitoring exercise was to provide data to assess the potential impact of the waste mass at Helenton Closed Landfill site on the local surface water environment and determine the extent of the longer term impact on the adjacent water courses associated with any seasonal fluctuations in water quality.

6.2Progress year 2007 - 2008

Four surface water monitoring rounds were undertaken at the site between October 2006 and August 2007. All surface water samples were analysed for a range of water quality indicators and potential contaminants. The results showed that elevated levels of contaminants were present within the surface waters adjacent to the site, however, it was unclear whether an intact pollutant linkage existed between the site and the surface waters. Recommendations for future activity consists of works to clarify the extent and concentrations of contaminants within the landfill and the characteristics of leachate within the site, in addition to further sampling of the local surface waters to determine the extent of any long-term impact.

6.3Plans for 2008 - 2009

Work on this location will be dependant on the allocation of financial support for the project.

7Muir Burn, Mossblown - Water Sampling

7.1Objective for year 2007 - 2008

The objective of the monitoring exercise was to provide data to assess the potential impact of the made ground at the Muir Burn, Mossblown site on the local surface water environment, and to determine the extent of the longer term impact of the made ground contaminants on the adjacent watercourses, taking into account any seasonal fluctuations in water quality.

7.2Progress year 2007 - 2008

Five surface water monitoring rounds were undertaken at the site between October 2006 and October 2007. All surface water samples were analysed for a range of water quality indicators and potential contaminants. The results showed that elevated levels of contaminants were present within the Muir Burn adjacent to the site. These contaminants were noted to increase in concentration as the burn flows along the site boundary. It was, however, not possible to determine if there was a pollutant linkage between the elevated contaminant concentrations present within the Muir Burn and the made ground that is thought to be present within the site, although there is visual evidence of a linkage.

Recommendations for future activity consists of works to clarify the extent and concentrations of contaminants within the made ground and the characteristics of leachate within the site, in addition to further sampling of the Muir Burn to determine any long-term impact.

7.3Plans for 2008 - 2009

Work on this location will be dependant on the availability for allocation of financial support for the project.

8Drumellan Street, Maybole – Ground Investigation

8.1Objective for year 2007 - 2008

In response to the potential risks identified by the desk study a preliminary assessment of the site comprising cable percussive boreholes with subsequent soil and groundwater sampling together with follow up gas monitoring was recommended.

The objectives of this preliminary assessment were to determine if a source of contamination is present at the site, to examine potential pollutant linkages and to confirm if significant risks to receptors are posed by any contamination identified.

8.2Progress year 2007 – 2008

The investigation consisted of six hand pits and three cable percussive boreholes, chemical analysis of soil and groundwater samples and four rounds of gas monitoring (carried out over a five week period).

Subsequently, a report was produced which contained the findings of the information review and assessment of the investigation results. The report stated that a source of contamination was located within the site, thought to be associated with materials andstructures that remain from the site’s former usage as a gas works. In addition, a number of potential pathways were identified requiring further investigation.

8.3Plans for 2008 - 2009

It is intended that a second phase of investigative works will be undertaken to gather additional data and to use this to further determine whether the site meets the statutory definition of contaminated land. The works will include; excavation of trial pits across the site, collection and testing of further groundwater samples, further gas monitoring, a geophysical survey of underground structures, and investigation of the nature of the potable water supply to the on-site buildings.

9Firth Terrace, Girvan – Ground Investigation

9.1Objective for year 2007 – 2008

As a result of the desk study findings a preliminary assessment of the site, comprising hand dug pits, soil and sampling and chemical testing was recommended.

The objectives of this preliminary assessment were to determine if a source of contamination is present at the site, to examine potential pollutant linkages and to confirm if significant risks to receptors may be posed by any contamination identified.

9.2Progress year 2007 - 2008

Initially a full information review was undertaken for the site, followed by targeted investigation during February 2008.

The findings of the information review and assessment of the investigation results were combined in a report which concluded that a source of contamination was located within the site likely to be associated with the site’s former usage as a gas works. A number of potential pollutant linkages were identified as requiring further investigation at the site. The purpose of these investigations would be to clarify the nature and extent of contaminants within the soil, the leaching of contaminants to the drinking water and the site’s ground gas and groundwater regimes.

9.3Plans for 2008 - 2009

Having established the presence of contaminants, this year it is intended that an investigation will be carried out in order to assess whether vapours are entering the NHS surgery located within the site. It is suggested that this should take the form of an initial questionnaire to assess conditions within the building and the practicalities of a gas monitoring exercise. In addition, a water sampling exercise should be undertaken to determine whether contaminants are entering the drinking water supply of the building.

10Miscellaneous

In addition, a number of smaller tasks were completed during 2007 -2008. In particular statistics were compiled for reporting to the Scottish Executive on progress under Part IIA, and training of the SAC team continued.

112008 – 2009 Key Activites

  • Substantial completion of Murray Gardens Remediation
  • Progress of risk assessment at the sites with established pollutant linkages
  • Continue steady progress of the inspection of potentially contaminated land in line with the published Strategy for Inspection
  • Further development of SAC team’s skills and experience via training and partnership with Jacobs

1

[1] South Ayrshire Council – BusinessLand and Premises Review – 2007;