Reinstatement of the Excavated Area with Clean Material
The excavated area was reinstated with clean material when it had been demonstrated that the site had been remediated in accordance with the relevant approvals and criteria.
Reinstatement activities included:
- Importation of fill, and backfilling and compaction of the excavated area to the designated levels in accordance with the detailed earthworks specification;
- Importation and placement of sub-grade materials;
- Revegetation of the site’s surface and maintenance of the new vegetation;
- Fencing works;
- Completion of the noise wall on the southern site boundary;
- Installation of heritage interpretation signage;
- Repairs to the shallow drain on the western boundary; and
- Repairs to the site access road and footpath area on Erskineville Rd.
Detailed earthworks specification
A detailed earthworks specification was developed by a competent geotechnical engineer that addressed the important geotechnical issues associated with material properties, backfill layer definitions, required compaction levels and testing requirements.
Materials used for backfill
Excavations were backfilled with Virgin Excavated Natural Material (VENM), Excavated Natural Material (ENM) or appropriate recycled materials (where approved by the EPA-accredited Site Auditor). Backfilling was performed as soon as possible after the remediation excavations were complete to mitigate risks associated with excavation collapse, slips and falls, and recontamination.
Backfill materials were subject to validation procedures as detailed in the Remedial Strategy and the Auditor-approved Remedial Works and Validation Plan. This included historical checks on the source of the material and chemical analysis to confirm that no contamination was brought back onto the site.
Following the completion of bulk backfilling works, topsoil was placed in accordance with the detailed earthworks specification. The thickness of the topsoil layer was determined by the revegetation strategy.
The western boundary of the site includes a steep embankment of varying height which leads down to an open stormwater drain and the site boundary fence. To the immediate west of the embankment and boundary are the residential properties located on Burren St.
The embankment in its original configuration presented a constraint for maintenance activities to the drain, boundary fence and vegetation. As a result, the embankment was redesigned and reinstated at a shallower profile than the original.
The redesign of the embankment considered impacts on the:
- Boundary fencing (including the noise wall);
- Revegetation and visual amenity;
- Hydraulics, drainage and erosion;
- Stability of the southern gasholder;
- Heritage interpretation; and
- Local community.