Some jobs are a little bit different. During the flooding that occurred in March earlier this year, there was considerable damage to roads and infrastructure throughout the Hawkesbury region. As part of the flood recovery, we were engaged by Hawkesbury City Council for the provision of inspections to assist Council in monitoring the stability of the severely damaged Greens Road in Lower Portland.
Since March we have been on site daily prior to sunrise, to observe the crack widths and lengths along Greens Road, as well as any indications of new cracks or other signs of movement of the road. As pictured below, along Greens Road there were two locations that were most significantly impacted.
Not only was a substantial part of the already narrow pavement lost, there was considerable cracking around the slip areas indicating general instability at each site.
The Slip Monitoring Process
Initially, Hawkesbury City Council closed site two to traffic, forcing residents north of the site to traverse Wheelbarrow Ridge Track and Wheelbarrow Ridge Road (approximately 20km) to access West Portland Road, just 3.5km to the south.
At site one, Council decided to place para webbing along the edge of the slip, impose a 5-tonne load limit, closely monitor it and leave it open to one lane traffic flows, controlled by traffic controllers. Barker Ryan Stewart was appointed to carry out monitoring while geotechnical investigation and design was undertaken.
Detailed observations and photographs were documented as a base line and monitoring of this site commenced on 29th March and has continued on a daily basis.
Due to the huge inconvenience being experienced by the local population north of site two, Council installed gates either side of the site, and subject to certain conditions, including a 3-tonne limit, the gates were to be opened between sunrise and sunset, again monitored by traffic controllers.
One of those conditions was that the site had to be inspected prior to the gates opening, by a suitably qualified and experienced Engineer to ensure there were no obvious changes which could indicate further instability. Our appointment has been extended to undertake this task on a daily basis in conjunction with the continued monitoring of site one.
At site two, the monitoring has been further refined by the placement of 13 monitoring stations which are measured by laser at each inspection and the readings documented along with two rain gauges for rainfall records. The road is closed should 10mm of rain fall in a 24 hour period.
During this time extensive geotechnical investigation and design is being carried out to enable the sites to be remedied.
While rising early enough to get on site by sunrise may sometimes feel onerous, it does have its benefits.
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