Careys Civil Engineering helped to build the Millerhill Energy from Waste (EfW) plant, which plays a key role in Edinburgh’s “Zero Waste” strategy.
We acted as specialist contractor on this important project, which aims to significantly reduce the volume of waste being sent to landfills. The Millerhill EfW plant forms part of our impressive energy-related portfolio.
It was our responsibility, on this project, to construct Millerhill’s vast waste bunker, as well as all the associated foundation slabs for the main building. We were also tasked with installing the external concrete slabs and the hard landscaping.
Robust procedures produce environmentally friendly, safe excavation works
In keeping with our dedication to protect the environment and minimise disruption to site surroundings, we implemented a close monitoring system during ground compaction works. This also kept us fully compliant with the project’s strict noise and vibration parameters.
In addition, before we started construction works at the Millerhill site – which is located on a former railway marshalling yard – we needed to divert and replace a Network Rail drainage culvert. To do this, we utilised SONED and CAT tools to trace the exact location required for the replacement unit.
On this project, it was also necessary for us to carry out extensive excavation works at depths of up to 10m, in order to construct the new waste bunker. By closely observing these works and providing extensive Safe Digging training for all groundworkers and supervisors, we ensured that, zero utility strikes occurred.
Efficiently constructing the waste bunker with thorough planning and an innovative approach
Once we concluded the excavation element of this project, we began to construct the waste bunker. We used a cost- and resource-effective slip form methodology, employing a 52m concrete pump to perform all concrete pours. The slip form process was deployed in three stages, in order to enable progressive adjustments.
We completed the bunker base in less than 12 hours with a single 900m3 concrete pour. During construction of the bunker itself – which stands 30m high and measures approximately 32m long by 15m wide – we poured 2,000m3 of concrete. We were able to successfully carry out the entire pouring process in under two weeks. This rapid pace, which expedited the construction programme, was also partially achieved by our implementation of 24-hour pouring shifts.
For the main elements of concrete pouring, we achieved substantial time-savings – finishing three weeks in advance of the programmed date and handing over this phase of the project to the client in October 2017. Our efficient and quick performance also enabled follow-on trades to commence early, helping to further reduce costs.
Rigorous concrete quality control measures enable high-quality results
We conducted extensive thermal monitoring and concrete testing throughout the project to help ensure that the client’s quality specifications were fully attained. For example, when pouring the 1,200mm-thick concrete floor slabs for the various structures on site, we utilised the expertise of a specialist material testing contractor to monitor the quality of every concrete pour.
Additionally, when working on previous bunker projects, we had identified potential risks in pouring in-situ tipping chutes. To help mitigate these risks, we devised a value engineering solution at Millerhill, which involved installing the chutes as pre-cast units.
Successful delivery of hard landscaping at Millerhill EfW
We began the hard landscaping phase of this project in September 2018. On this phase of the Millerhill development it was our responsibility to carry out:
- Bulk excavation – which required the cutting of 5,500m3 of material and filling of another 8,000m3 of material, all of which had been stored on site from the first phase of works
- Construction of:
- Two attenuation ponds – with respective volumes of 5,000m3 and 1,100m3
- Ornamental Pond – with a volume of 800m3
- Asphalt footpaths – with an area of 1,000m2
- Bark footpath – with an area of 1,500m2
- Mono blocking – an area of 1,100m2
- Top soiling – which necessitated the importation of 1,200m3 of soil
- Planting and seeding