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Site Preparation & Civils

The flat, drained, load-bearing platform that a grid-scale battery site is built on - earthworks, foundations, drainage, buried cable routes and the access road that has to carry a low-loader and a crane on the same afternoon.

Last updated 2026-09-06

Typical duration

Typically 8-16 weeks for the civils package on a scheme of a few tens of megawatts, though ground conditions and winter weather move it more than anything else does.

What is Site Preparation & Civils?

A grid-scale battery site is a civils project with electrical kit parked on top of it. Strip back the containers and what is left is a graded platform, a ring of hardstanding, rows of concrete plinths or piles, a drainage system, a buried duct network, an earthing grid, a perimeter fence and an access road. Almost all of that is built before a single battery arrives, and almost all of it is invisible once the site is finished. The platform is usually a field, a corner of a farm, a scrap of brownfield or a plot bought specifically because it sits next to a substation, so the first task is turning agricultural or derelict ground into something that will carry heavy plant in February.

The loads drive the design. Battery enclosures are dense and they land as concentrated point loads, not spread ones, so the ground investigation matters more here than the modest footprint suggests. Weak or variable ground pushes the designer towards piles or ground improvement rather than a spread slab. Conversion plant and transformers are heavier still and often want their own bases with bunding. Cranes need prepared, proven hardstanding to set up on, and the outrigger loads from a crane lifting a container are usually the heaviest thing the platform ever sees. None of those figures are guesswork on site: they come from the designer, and the platform is built to the drawing rather than to whatever the ground looks like it can take.

Everything buried goes in early, because once the units land there is no digging between the rows. Ducts for the direct current cabling, the medium voltage collection route, the auxiliary supplies, comms and the earthing grid all get installed, proved and recorded while the site is still open ground. Drainage has to deal with a surface that is largely impermeable once finished, so attenuation, outfalls and any containment required by the fire strategy are set out at the same time. Add the planning conditions - screening, landscaping, noise, ecology, wheel washing at the site entrance - and the civils package quietly becomes half the programme, while the grid connection date sits over the whole thing and does not move.

Compare the methods at a glance

Method comparison graphic coming soon

When and why is Site Preparation & Civils used?

Civils comes first and it sets the pace for everything after it, because a battery scheme is a repetitive assembly operation that only works if the platform is right before the first delivery. The order is fixed by physics and logistics rather than preference: you cannot lift a container onto a plinth that has not cured, you cannot pull cable through ducts that were never proved, and you cannot dig a trench under a row of live enclosures. Ground conditions decide the foundation type, the ground investigation decides the ground conditions, and both need to be settled early because a change from slab to piles is a change to the programme, the plant and the price. The commercial driver is the connection date agreed with the network operator. That date is fixed years in advance, revenue starts when the site energises, and every week lost in the mud is a week of income gone, so the civils are usually resourced hard and run to a tight, repetitive rhythm. Do the platform properly and the rest of the project becomes a series of clean, repeatable operations. Rush it and the whole scheme spends the next three months working around settlement, ponding, blocked ducts and plinths that are not where the drawing says they are.

Types of Site Preparation & Civils

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

Reinforced concrete slab or raft platform

A continuous reinforced slab carrying the enclosures, the access route around them and often the conversion plant as well. Simple to set out, tolerant of the point loads and easy to keep clean, but it needs decent ground beneath it and it is the most concrete-hungry option.

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Individual plinths or ground beams

In-situ or precast plinths under each enclosure, with a granular or surfaced running strip between the rows. Less concrete than a full raft and quicker to programme, but the setting-out tolerance becomes critical because every unit has to sit level and square across all of its bearing points.

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Piled or screw-pile foundations

Used where the ground is soft, made, variable or contaminated and a shallow solution would settle. Piles carry the load to competent strata, with capping beams or a steel frame spreading it to the enclosure bearing points. More plant and more testing, but it removes the settlement argument entirely.

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Engineered granular platform

A compacted, surfaced platform with the units bearing on it directly or through spreader skids. The lightest-touch option and the easiest to reinstate at the end of the site life, which suits temporary or leased land, but it depends on good ground and disciplined compaction.

Explore this method

Best suited for

  • Grid-scale storage plots adjacent to an existing substation or connection point
  • Brownfield and former industrial land where the platform can be engineered from scratch
  • Co-location alongside solar or wind schemes sharing a single connection
  • Schemes with a fixed connection date, where a fast repetitive civils package protects the programme

Site Preparation & Civils: step by step

  1. 1

    Step 1: Prove the ground and fix the platform level

    The ground investigation is read properly before anything is priced, not after the excavator arrives. Trial pits and boreholes tell the designer what the strata do, where the water table sits, whether the plot is made ground or fill, and whether there is contamination to be managed. Alongside it comes the topographical survey, the utility search and the flood assessment, and out of all of that the designer fixes the platform level and the foundation type. The platform level is a balancing act: high enough to stay dry and drain, low enough to keep the earthworks cut-and-fill balanced and the screening effective, and consistent enough that the enclosures sit in flat rows. Getting the level agreed early matters, because every duct invert, drainage fall and plinth soffit on the project is measured from it.

  2. 2

    Step 2: Build the access road, site entrance and compound

    A battery site takes deliveries that most rural lanes were never built for. The access road, site entrance and any junction improvements are usually the first permanent works, built early and to the full construction specification so that the low-loaders and cranes arriving later are running on something proven rather than something hopeful. Visibility splays, gates, turning areas and passing places come from the transport assessment and the planning conditions. The site compound goes in at the same time: welfare, offices, secure storage, parking, wheel wash and the laydown areas that will hold cable drums, plinth reinforcement and, later, enclosures waiting to be lifted. Getting the compound in the right place saves months of double-handling, because the crane route and the delivery route have to coexist for the whole build.

  3. 3

    Step 3: Strip, cut and fill to formation

    Topsoil is stripped and stockpiled where the planning conditions say it can be, and the site is cut and filled to the design formation. On a well-planned scheme the earthworks balance on site, because carting material off is expensive and carting it in is worse. Filling is placed and compacted in layers to the earthworks specification, with the material type, layer thickness and compaction method all coming from the designer rather than from habit. Unsuitable material is dug out and replaced. Formation is inspected and tested to whatever the specification calls for before anything is built on it, and it is protected once accepted - a formation left open through a wet week is a formation that has to be reworked, and reworking a platform after the plinth reinforcement has arrived is a bad week for everybody.

  4. 4

    Step 4: Install drainage and containment

    A finished battery site sheds a lot of water, so the drainage is designed as a system rather than added as an afterthought: collection across the hardstanding, attenuation to hold back the peak, an outfall or discharge point agreed with the drainage authority, and interceptors or penstocks where the fire strategy or the transformer bunding calls for firewater and oil to be held on site rather than sent downstream. Pipe runs, chambers and the attenuation structure go in with the earthworks while the site is open. Falls are set by instrument and checked, because on a flat platform a small error in level becomes a permanent puddle exactly where the maintenance team needs to stand. The system is tested and recorded before it disappears under the surfacing.

  5. 5

    Step 5: Construct the foundations and plinths

    Foundations follow the design: piles installed and tested, or bases and plinths excavated, blinded, reinforced and cast. This is the step where accuracy earns its money, because every enclosure that arrives later has fixed bearing points and fixed cable entry positions, and the plinths have to match them across the whole row. Setting out is done from the site coordinate grid and checked independently before the concrete goes in, not after. Reinforcement, cover, cast-in fixings and any cable entry boxouts are inspected against the drawing at the pre-pour stage. Concrete is placed, cured and protected, and the finished levels are surveyed and recorded so that any local low spot is known before the crane turns up rather than discovered underneath a suspended container.

  6. 6

    Step 6: Lay the buried ducts, cable routes and earthing grid

    Trenches are cut for the direct current runs between the enclosures and the conversion plant, the medium voltage route out to the connection point, the auxiliary supplies, the comms and the fire and security cabling. Ducts are laid to the design layout with separation between systems as the designer requires, bedded and surrounded, marked and proved with a mandrel and draw rope so that a duct blocked by a stray stone is found now rather than on the day of the cable pull. The earthing grid is installed at the same time - conductor, connections and any earth electrodes - and its continuity is tested and witnessed before the backfill goes on, because it is one of the few safety-critical systems on the site that is completely inaccessible afterwards. Everything is surveyed as-built before it is covered.

  7. 7

    Step 7: Surface the platform and complete the external works

    The running surface is built up in layers to the specification, whether that is a bound surface, a stone finish or concrete, with kerbs, edgings and drainage gullies formed as the drawing shows. Crane pads and delivery routes are finished first, because the installation team needs them. Firefighting access routes and any hardstanding required by the fire strategy are built to the same standard as the rest, not as a token strip. Around the outside come the perimeter security fence, gates, lighting columns, camera posts and the ducting that serves them, plus the landscaping, bunds, hedging and habitat works that the planning consent almost always requires. These are the items that get squeezed at the end of a programme, which is exactly why they are worth building while the plant is still on site.

  8. 8

    Step 8: Hand the platform over to the installation team

    The platform is handed over as a finished, surveyed, documented product rather than as a muddy field with some concrete in it. Plinth levels and positions are re-surveyed and issued, duct routes and earthing as-builts are handed across, drainage records and test results are collected, and any deviation from the design is written down and agreed rather than left to be discovered. Crane positions are confirmed against the finished levels and the ground bearing information. Access, laydown and welfare arrangements are set for the delivery phase, which is a very different operation from the earthworks phase and needs the site laid out differently. A clean handover here is what lets the container installation run at the fast, repetitive tempo that the connection date depends on.

Plant & equipment

  • Tracked excavators for bulk dig, trenching and foundation excavation
  • Dozers, graders and articulated dumpers for cut, fill and haul
  • Vibrating rollers and compaction plant for the earthworks and surfacing layers
  • Machine control and survey kit - total stations, GNSS rovers and levels
  • Concrete supply, pumps, vibrators and power floats for slabs and plinths
  • Piling rigs where the design calls for piled or screw-pile foundations
  • Telehandlers and rough-terrain forklifts for materials, ducts and reinforcement
  • Water bowsers, wheel wash, silt management and welfare for the compound

Quality control & testing

  • Setting out taken from the site coordinate grid and independently checked before every pour
  • Formation inspected and tested to the earthworks specification before anything is built on it
  • Compaction records kept layer by layer, with material type and method as specified
  • Concrete sampled and tested, with pre-pour inspection of reinforcement, cover and cast-in fixings
  • Plinth and base levels surveyed after casting and issued to the installation team
  • Ducts proved with mandrel and draw rope, and drainage tested before backfill
  • Earthing grid continuity tested and witnessed before it is covered
  • As-built survey of every buried route recorded while the trench is still open

Safety watchpoints

  • Excavation collapse and buried services - trenches supported or battered as the temporary works design requires, and existing services located before digging
  • Plant and people separation across a large open site with continuous vehicle movements
  • Deliveries on rural roads and at the site entrance, where the interface with the public is the biggest exposure
  • Working next to an existing substation or overhead line, where the network operator sets the exclusion arrangements
  • Concrete and cementitious materials - skin contact, eye injury and manual handling
  • Slips, trips and drowning risk around open attenuation structures and deep chambers
  • Weather - a battery site is an exposed, treeless platform, and wind, cold and water all bite
  • Ground contamination on brownfield plots, managed under the project's own remediation strategy

Common defects to hunt

  • Plinth levels or positions out of tolerance, so enclosures sit twisted or bear unevenly
  • Settlement under enclosures or plant because fill was placed without proper compaction control
  • Ponding on the platform from falls set by eye rather than by instrument
  • Ducts blocked, crushed or laid to the wrong route, discovered on the day of the cable pull
  • Earthing grid damaged by later excavation because the as-built was never issued
  • Access road built to a lighter specification than the crane and low-loader loads demand
  • Drainage discharging without the containment the fire strategy requires
  • No record of what was buried where, leaving the operator to dig speculatively for the next twenty years

How long does Site Preparation & Civils take?

Typical duration: Typically 8-16 weeks for the civils package on a scheme of a few tens of megawatts, though ground conditions and winter weather move it more than anything else does..

Related processes

This is where every build begins.

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02 - Battery Container Installation