Site History
Site name and location Muirend Playing Fields, Giffnock, south‑west Glasgow. The site is used for sports and recreational purposes and is bounded along its eastern and part of its northern perimeter by the Merry Burn.
Historical contamination summary
- Period of disposal: 1950s.
- Nature of waste: Chromium‑bearing wastes, specifically highly alkaline chromite ore processing residues.
- Pathway to receptor: Leaching of chromium, particularly hexavalent chromium (chromium VI), into the Merry Burn.
Observed effects: Visual discolouration of the burn and damage to surrounding flora consistent with chromium(VI) contamination.
Remediation works prior to 2014
Remedial measures carried out before 2014 included:
- Capping of the waste to limit infiltration.
- Installation of a new drainage system isolated from the contaminated waste.
- Construction of up‑gradient slurry cut‑off walls along the northern, southern and western boundaries.
- Dredging of the Merry Burn to remove contaminated sediments.
Although these works were expected to substantially improve surface water quality, monitoring showed that chromium(VI) concentrations in the Merry Burn did not fall as much as anticipated and visible discolouration persisted. Subsequent investigations identified multiple locations where contaminated waste continued to break through into the burn.
Interim controls and further works
- Gabion baskets and peat barriers were installed at key locations to intercept and prevent further direct discharge of chromium‑bearing material into the burn.
- Despite these measures, ongoing leaching was evident and required further assessment and treatment.
2014 Envirotreat assessment and remediation
- Site visit findings: Water entering the Merry Burn from the gabion baskets had a measured pH in excess of 11.5, indicating continued release of highly alkaline waste.
- Leachate analysis: Total chromium ≈ 26,000 μg/L, of which 20,000 μg/L was hexavalent chromium (Cr(VI)). For context, the Environmental Quality Standard (EQS) for Cr(VI) is 3.4 μg/L.
- Options appraisal: Following the appraisal, Envirotreat was commissioned to install a permeable reactive barrier (PRB) using E‑Clay and the recognised ChromeSorb technology to treat chromium(VI) in leachate before it reached the burn.
- Implementation: A section of ChromSorb PRB was installed in 2014 to intercept and chemically immobilise the chromium (VI) onto the PRB substrate.
