Challenges arose from a combination of site conditions: excess topsoil, water-adverse material (Alluvium) and prolonged periods of wet weather. These factors impacted the suitability of materials for re-use according to the original geotechnical reports, the overall balance of onsite cut/fill, and the ongoing accessibility for construction. This resulted in lodgement of multiple challenging contractor variations.
Other challenges included:
- Requirement for additional scope of works, such as external sewer and electrical infrastructure upgrades.
- Poor weather and difficulty in completing construction resulted in an extension to duration of works.
As Superintendent, Orion’s role was:
- Defining the extent of variations and sorting them into manageable and measurable stages of work. The contractor prioritised immediate site access as part of the construction approach. Consequently, the project was divided into multiple stages, leading to several variations. Orion’s task was to outline specific inclusions and timing for each variation, facilitating the contractor’s access to key areas like roadways and lots and managing earthworks balance on site during the early stages. While this approach increased ongoing construction and weather-related challenges (such as pumping design roadways), it was deemed less risky for the client and was the contractor’s desired method. Presently, further technical solutions and consultations are addressing these issues.
- Assessing, agreeing on and communicating the contract rates, including modifications. This allowed the contractor to proceed with onsite works during favourable weather, bypassing delays caused by uncertainties such as ground condition investigations and price variation.
- Leveraging updated geotechnical guidelines and ongoing trial testing (such as stabilisation and blending) for optimal outcomes. Regular inspection and review of onsite materials to guide us towards the most technically sound and cost-effective solutions aligned with the original contract rates. Clear directives mandating daily onsite geotechnical assistance, with weekly meetings involving all parties to ensure a balance of the site mass haul.
- Verifying the contractor’s submitted quantities through a first-principles assessment using geotechnical onsite test pits and a detailed breakdown of quantities street by street and area by area. This process promptly ensured the integrity of the Bill of Quantities (BOQ), preventing the inclusion of both the original contract quantities and additional rates intended to cover the comprehensive process of winning, loading, hauling, spreading, compacting, and testing operations.
