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Site Civils & Heavy Foundations

The platform, piles and heavy bases a capture plant stands on - built on a congested brownfield plot beside a working emitter, where the ground is already full of somebody else's foundations and services and the host plant never stops for you.

Last updated 2026-09-06

Typical duration

Typically 6-12 months for the civils package on a full-scale retrofit. The volume of concrete is rarely the driver - working around a live host plant, its permits and its shutdown calendar is.

What is Site Civils & Heavy Foundations?

Carbon capture civils are almost never greenfield civils. The plot is a leftover corner of an operating power station, cement works, energy-from-waste plant, refinery or chemical works, chosen because it is the only ground left within reach of the flue gas duct. That means made ground, old foundations from plant demolished decades ago, abandoned drains, live buried services nobody has drawn properly since the site was built, and contamination from whatever the works used to do. The first job on a capture site is not digging. It is finding out what is already down there, thoroughly enough that the piling rig does not discover it the hard way.

The loads are heavy and awkward. A capture plant is a collection of tall slender columns, thick-walled vessels, large rotating machinery and a dense forest of pipe racks. The tallest item is usually the absorber, and a tall column on a small footprint is governed as much by wind and overturning as by its own weight, so its base is a serious piece of engineering in its own right. Rotating machinery wants stiff, heavy, isolated foundations. Vessels want accurate, level bearing points. Pipe racks want long lines of piles set out precisely, because the steel above them is prefabricated and will not forgive a rack line that wanders. On made ground almost all of that ends up piled.

The real constraint is the neighbour. The host plant is live, it belongs to somebody else, and it has its own permit system, its own exclusion zones, its own shutdown calendar and its own firm view about vibration, dust, traffic and noise. Piling next to a running boiler house or a live kiln happens under limits set by the operator, monitored continuously, and stopped when the readings say stop. Access runs through a working industrial site on roads never sized for a crawler crane. Laydown is scarce and gets fought over daily. Every one of those is a programme risk, and every one of them is far cheaper to solve on a drawing than on the day.

Compare the methods at a glance

Method comparison graphic coming soon

When and why is Site Civils & Heavy Foundations used?

Civils come first and they set the tempo for the whole project, because a capture plant is an assembly job that only works if the foundations are complete, cured, surveyed and accurate before the first module arrives. The sequence is not negotiable. You cannot land a module on a cap that has not been cast, you cannot pile under a pipe rack that is already standing, and you cannot dig a service trench across a plot that is full of steel waiting to be lifted. Retrofit adds a second driver on top of that. The tie-in into the host plant can usually only be made during a planned outage, that outage is booked years in advance, and the whole construction programme is arranged backwards from it. Miss the window and the next one may be a year away, with the plant sitting finished and idle in between. Commercially the scheme runs on a support arrangement and a transport and storage agreement with fixed dates, so lost weeks are lost revenue and, at worst, a renegotiation of the deal that funded the thing. The other reason to take the civils seriously is accuracy. Modules and racks are built in a fabrication yard to their own dimensions and they arrive expecting the foundations to match. Setting out on a congested retrofit plot, working off a grid that has to tie into the host plant's existing structures, is genuinely difficult, and a base in the wrong place is normally discovered by a crane driver with a module hanging over the site. Get the ground right and the rest of the build becomes a series of clean lifts. Get it wrong and every following trade pays for it.

Types of Site Civils & Heavy Foundations

Explore each method in depth - benefits, limitations, plant and quality control on its own page.

Piled foundations with caps and ground beams

The default on made ground and old industrial land. Piles carry the load past the fill, the demolition rubble and the soft layers into competent strata, with caps and ground beams spreading it to the vessel, column and rack bearing points. More plant, more testing and more noise than a shallow solution, but it removes the settlement argument on ground whose history nobody can fully account for.

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Heavy reinforced mats and machinery bases

Thick reinforced blocks and mats under the compression train, pumps, fans and other rotating equipment, usually piled beneath and often separated from the surrounding slab. The mass and stiffness are there to deal with how the machine behaves when it runs, and the design comes from the machinery supplier and the structural designer working together rather than from a standard detail.

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Ground improvement and engineered working platform

Used where the ground is poor but the loads are modest, or where a platform has to carry piling rigs and crawler cranes before the permanent works start. Treatment, replacement or reinforced granular layers turn variable made ground into something predictable. Quieter and cheaper than piling, but it only works if you genuinely know what is underneath.

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Piled pipe rack and module support lines

Long, repetitive lines of piles and plinths carrying prefabricated pipe racks and module support steel. The engineering is simple; the discipline is not. Every position and level has to match steel that is already built and sitting on a trailer, so the whole line is surveyed and signed off before the first bay is lifted.

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Best suited for

  • Retrofit capture plants squeezed onto operating industrial sites with no spare land
  • Made ground, former industrial plots and sites with a long demolition history
  • Tall columns and heavy rotating machinery needing accurate, stiff, settlement-free support
  • Projects built around a fixed tie-in outage, where foundation accuracy protects the lift programme

Site Civils & Heavy Foundations: step by step

  1. 1

    Step 1: Read the ground and the site's own history

    The ground investigation on a capture retrofit is half geotechnics and half archaeology. Boreholes and trial pits tell the designer what the strata do, where the water sits and whether there is contamination to manage, but the site archive matters just as much: original construction drawings, demolition records, old plant layouts, historic aerial photography and whatever the operator's long-serving engineers remember. Buried mass concrete from a demolished chimney or a forgotten culvert will stop a piling rig dead, and finding it now is a design decision while finding it later is a claim. The designer uses all of it to fix the foundation type, the platform level and the piling method. Contamination and groundwater findings also shape the excavation strategy, the disposal route and the containment the finished plant will need, so the investigation is scoped once and scoped properly rather than repeated in instalments.

  2. 2

    Step 2: Find the buried services before the rig does

    An operating industrial site is threaded with live buried services, and the drawings are usually incomplete, out of date or both. The survey combines the operator's records, electromagnetic location, ground-penetrating radar and, where it matters, physical trial holes dug by hand under the host plant's permit system. Everything found is marked on the ground and added to a controlled composite drawing that every excavation permit is then issued against. This is not a formality. A capture plot typically sits over high-voltage cables feeding the works, cooling water mains, process lines, fire mains and instrument routes, and striking any of them shuts the host plant down, which is a far more expensive event than the repair. Where services cannot be avoided they are diverted, protected or exposed and supported before the works reach them, and the diversion is agreed with the asset owner rather than assumed.

  3. 3

    Step 3: Enabling works, demolition and clearance inside a live plant

    Clearing the plot usually means taking out redundant structures, foundations, tanks, drains and hardstanding that sit within a working facility. The demolition is small in volume and difficult in every other respect: restricted access, live plant on the other side of the hoarding, asbestos and other hazardous materials in older structures, and an operator who will not tolerate dust, debris or unplanned noise. Temporary works carry a lot of weight here - propping, edge protection, hoardings and the protection of adjacent live assets are all designed rather than improvised. Obstructions found below ground are broken out and recorded. At the same time the boundary between the construction site and the operating plant is physically established, with its own gates, its own signage and a clear line that both organisations understand, because that line governs who is in charge of what for the next two years.

  4. 4

    Step 4: Fix access, laydown and the crane positions

    The heaviest things this site will ever see arrive later, so the routes for them are settled now. That means an assessment of the haul route from the port or the highway, including bridges, culverts, buried services, overhead lines, turning radii and headroom through the host plant, and it usually means strengthening or rebuilding sections of internal road. Crane pads and module standing areas are designed as engineered structures, not as a thicker layer of stone, because the outrigger and track loads from a large crawler crane are among the biggest point loads on the project. Laydown is allocated deliberately - modules, racks, pipe spools, reinforcement and cable drums all need space, and space is the one thing a retrofit plot never has. Getting this layout right saves months of double handling; getting it wrong means every lift is preceded by a shunt.

  5. 5

    Step 5: Install and prove the piles

    Piling on a capture retrofit runs under constraints most piling jobs never see. The method is chosen partly for capacity and partly for how much noise and vibration the neighbours will accept, and the limits come from the host plant operator and the local authority rather than from the contractor. Monitoring runs continuously on sensitive adjacent structures and equipment, with agreed trigger levels and an agreed response when they are reached, which sometimes means stopping. Each pile is recorded as it is installed, obstructions and refusals are reported the same day rather than at the end of the week, and the testing regime the designer specified - integrity testing across the population, load testing on selected piles - is carried out and witnessed. Pile positions and levels are surveyed after installation, because caps and bases are designed around where the piles actually are, not where they were meant to be.

  6. 6

    Step 6: Cast the caps, mats and heavy bases

    This is where accuracy earns its money. Pile caps, machinery mats, column bases and rack plinths are excavated, blinded, reinforced and cast, and every one of them carries cast-in items that later equipment depends on: holding-down bolt groups, pockets, boxouts, earthing points and grout details. Bolt groups are set with steel templates, checked before the pour and re-surveyed afterwards, because a module arriving on a low-loader has fixed hole positions and no adjustment. Pre-pour inspection covers reinforcement, cover, cast-in items and the cleanliness of the excavation, and it is signed off by someone who did not fix the steel. Large machinery bases are placed with a planned pour sequence to control heat and cracking, then cured and protected properly. Concrete is sampled and tested with the results traceable back to the pour they came from, so a query about one base is not a query about all of them.

  7. 7

    Step 7: Build the drainage, containment and buried systems

    A process plant sheds several different kinds of water and they are not allowed to mix. Clean surface water, potentially contaminated process drainage and firewater run in separate systems, with containment, interceptors and holding capacity sized by the designer and agreed with the regulator through the site's permit. Bunding around tanks and chemical storage is built as a designed structure. Alongside the drainage go the buried duct routes for power, control and instrumentation, the earthing grid, and the pits and chambers that serve them. All of it is installed while the plot is still open, tested before it is covered and surveyed as-built before the backfill goes on, because once the modules land nothing underneath them will be reachable again for the life of the plant. Falls on a flat industrial plot are set by instrument, not by eye, or the operator inherits a permanent puddle in the worst possible place.

  8. 8

    Step 8: Survey, protect and hand the foundations over

    The civils package is handed over as a measured, documented product. Every base level, bolt group position, plinth and pile is surveyed and issued to the erection contractor as a set of as-built coordinates, so that any deviation is known and resolved on paper before a crane is booked. Drainage and duct as-builts, concrete test results, pile records and monitoring data are collected into the project record rather than left in a site cabin. Finished surfaces, bolt threads and grout faces are physically protected, because months will pass between casting and erection and a bolt thread damaged by a passing excavator holds up a lift. Crane pads are confirmed against the ground bearing information the crane supplier is working to. Access, laydown and welfare are then rearranged for a completely different phase, because the plant that installs modules bears no resemblance to the plant that dug the holes.

Plant & equipment

  • Piling rigs selected for restricted headroom, limited working room and noise limits
  • Tracked excavators, breakers and crushers for enabling works and obstruction removal
  • Vibration, noise and dust monitoring equipment linked to the host plant's agreed limits
  • Total stations, GNSS rovers and precise levelling kit tied into the host site grid
  • Concrete supply, pumps, vibrators, curing protection and temperature monitoring for large pours
  • Mobile and crawler cranes for reinforcement cages, bolt templates and precast units
  • Service location equipment - electromagnetic locators and ground-penetrating radar
  • Welfare, wheel wash, silt management and dust suppression suited to a controlled industrial site

Quality control & testing

  • Setting out tied to the host plant grid and independently checked before every pour
  • Pile records kept rig by rig, with integrity and load testing to the regime the designer specified
  • Holding-down bolt groups set with steel templates and re-surveyed after casting
  • Pre-pour inspection of reinforcement, cover, cast-in items and boxouts against the current drawing
  • Concrete sampled, tested and cured, with every result traceable to the pour it came from
  • Levels and positions of every base surveyed and issued to the erection contractor before lifting starts
  • Buried drainage, containment and ducts tested and proved before backfill
  • Vibration and settlement monitoring records kept for the host plant's adjacent structures

Safety watchpoints

  • Working inside a live process plant under the operator's permit system rather than the contractor's
  • Unknown and undrawn buried services, including live high-voltage cables and process lines
  • Piling and heavy plant close to occupied buildings and running assets, with vibration limits actually enforced
  • Contaminated and made ground, managed under the project's own remediation strategy
  • Excavation collapse, flooding and confined space entry in deep pits and chambers
  • Simultaneous operations, with construction traffic sharing narrow roads with the host plant's own movements
  • Overhead lines, pipe bridges and restricted headroom limiting where cranes and rigs can stand
  • Shared emergency arrangements with the host plant, including site alarms the construction workforce has never heard before

Common defects to hunt

  • Bolt groups out of position or level, so a module arrives and will not sit down
  • Piles refusing early on undrawn obstructions, wrecking the programme rather than the design
  • Damage or settlement to host plant structures because vibration limits were nominal rather than monitored
  • Machinery bases built without the stiffness the supplier assumed, so the train never runs sweetly
  • Buried services struck during enabling works because the survey was a drawing rather than a dig
  • Drainage that fails to segregate process effluent, firewater and clean surface water
  • Bolt threads, grout faces and cast-in items damaged in the gap between casting and erection
  • No as-built record of what was piled, cast or buried, leaving the operator blind for the life of the asset

How long does Site Civils & Heavy Foundations take?

Typical duration: Typically 6-12 months for the civils package on a full-scale retrofit. The volume of concrete is rarely the driver - working around a live host plant, its permits and its shutdown calendar is..

Related processes

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02 - Capture Plant Installation