CLIENT: Brisbane City Council
INDUSTRY: Local government, QLD
TYPE OF PROJECT: The desilting of York’s Hollow.
York’s Hollow is a waterbody that was constructed as a part of the Inner City By-Pass (ICB). It is located adjacent to the ICB in Victoria Park at the end of Gilchrist Ave (Herston). The pond receives water from run-off from the ICB and adjacent catchments of Kelvin Grove. Sediment accumulation over years has made the pond shallow in some areas that in heavy rain events can lead to over-topping of the structure. The pond itself contains numerous aquatic fauna. Furthermore, its perimeter is lined with protected flora such as Moreton Bay Fig trees and other significant species.
WHEN: June-August 2016
VALUE: $1.2m
BRIEF:
PMA was invited by Brisbane City Council (BCC) to tender for the role of desilting of the York’s Hollow Environmental Detention basin in late 2015.
Upon reviewing the scope of work required, PMA offered BCC an alternative methodology to what council initially proposed. PMA’s solution included available technology that offered less intrusive environmental strategies. Combined with PMA’s vacuum extraction capabilities, a viable and cost-effective alternative was successfully proposed to BCC and PMA was awarded the project in June 2016.
CHALLENGES:
Successfully delivering this complex project required PMA to overcome a number of significant challenges. These included:
- Difficulties in accessing the pond and positioning equipment into the pond without disturbing surrounding protected vegetation. Limited access was available via temporarily closed pedestrian paths to locate extraction equipment and storage vessels.
- An extremely high volume of cyclists and pedestrian traffic to divert around the works site.
- Constrained time frame to minimise period of path closure.
- High level of public scrutiny.
- Significant, unseasonal rain events were experienced during delivery of the works that overtopped barriers and inundated the extraction areas.
OUTCOME:
A total of 1,236.7m3 of sediment was extracted from York’s Hollow pond over 33 production days out of a total of 39 days on site. This included down time due to wet weather and equipment maintenance and repair. Three major rain events impacted the progress of the project and additional resources such as labour and vacuum trucks were allocated to the project to ensure its timely completion. PMA completed this challenging job with:
- Zero public complaints.
- Zero non-conformances for any aspect of the project.
- Zero H&S incidents or injuries
PMA also received the following public commendation for our work on York’s Hollow pond:
My Dear Lord Mayor,
I would like to thank everybody involved in the recent dredging of York’s Hollow. When we were told the work was going to be done, I was worried because I consider the area to be environmentally important. However, on completion of the job, I was grateful to see everything restored back to as close to normal as possible. Many of the ducks, swamp hens, and other water birds have carried on as though their lives weren’t interrupted at all. This would have been difficult job, and it could have been done badly if it had not been planned and carried out as well as it was. Would you kindly pass my thanks on to all concerned.
Anonymous grateful ratepayer.
