Following demolition and removal of structures lead and hydrocarbon contaminated waste was excavated and placed within the constructed containment cell under Level One Geotechnical supervision and project Construction Quality Assurance (CQA) Engineering standards. The lead contaminated material was contained and sealed with a welded High-Density Polyethylene (HDPE) liner the Hydrocarbon impacted material then placed on top and capped with a Geosynthetic Clay Liner (GCL). An independent leachate collection system was installed to collect any remnant mobile liquid contaminants.
Synergy drew on experience to pioneer solutions that ensured BBTC benefited from successful remediation of the site in accordance with the projects Remedial Action Plan as approved by the EPA Site Auditor. During the excavation of the containment cell sharp / fragmented rock was encountered along the supporting batter face, which would cause potential damage to the GCL after placement. To overcome this, fine grained clay material was placed and compacted using a excavator compaction plate attachment across the batters. The installation and compaction of the clay material created a smooth surface removing the risk of puncture allowing suitable bedding of the GCL lining system and quality conformance.
Through careful excavation and resource separation Synergy was able to beneficially reuse materials approximately 9000m3 of clay shale and hard rock as a “rock mulch” to stabilise validated areas and satisfy erosion and dust control criteria.