Concrete foundations for Valero’s Pembroke Refinery

In one of our longest ever continuous concrete pours, GD Harries and Sons built foundations for one of Europe’s largest and most complex oil refineries.

At the Pembroke Refinery in Milford Haven, a massive £127 million investment by Valero to build a combined heat and power (CHP) cogeneration plant, would enable the generation of 45MW of electricity and supply the refinery with steam helping the production of gasoline, diesel, jet fuel, heating oil and low sulphur fuel oil.

The new plant was completed mid 2022 consisting of a combustion turbine generator (CTG) and heat recovery steam generator (HRSG). The concrete foundation for the CTG was huge, at almost 500m³, and there were concerns that the proposed ready-mix concrete might not be suitable for such a large mass, and cracking may occur due to the heat from the chemical reaction in the concrete mix.

The concrete specification needed to meet specifical requirements for strength, core heat targets and aggregate type. Working closely with Trant Engineering, we developed a concrete mix design, which had never been used in the UK before, with 80% ground granulated blast furnace slag (GGBS). We trialled these at our laboratory with excellent results and found the mix to be exceptional in terms of strength.

It was decided that the structural formwork would be insulated for 28 days. Thermocouples were installed in the rebar through the centre of the slab so the temperature could be closely monitored.

When it came to pouring the concrete foundations, everything was planned to the letter. GD Harries and Grant worked together over a 24-hour period, relaying our special concrete mix from our plants at Bolton Hill and Narbeth. Deliveries were coordinated so as not to congest the busy working site. Our locally sourced aggregates worked well with the concrete mix and helped with the logistics.

“We started the large pour at six o’clock in the morning” explained our ready-mix technical manager Garry Batte, “and the last truck left the site at 4.30pm having delivered a total of 483m³. The logistics were testing, particularly ensuring the consistency of the mix and coordinating deliveries from two plants using 16 ready-mix trucks each doing four trips, but it all went without a hitch.”

When the test results for the hardened concrete were returned, everything was in line with the design, and the thermocouple data confirmed that the core temperatures remained low. This crucial part of the project was delivered on time with no programme delays.

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