A CCTV drain survey sometimes comes back showing a collapsed pipe, or one so deformed that nothing else will fix it. When that happens, excavation is what’s left. We recommend it only once relining, patch repairs, and high-pressure jetting have all been ruled out by the survey footage. Excavation means digging down to the pipe, taking the damaged section out, and putting a new one in its place.
A drain that’s reached this point doesn’t usually give much warning first. A collapsed section packs silt and debris into the gap, and water backs up behind it instead of draining away. Above ground, a backed-up drain can show as standing water in a gully that won’t clear, a section of path or lawn dipping slightly, or a smell around the affected spot that persists even after the line’s been rodded or jetted.
Call 0141 673 3535 if a survey has already flagged excavation, or if you’re still trying to work out whether it’s come to that. We’ll talk through what the camera found, the alternatives that were ruled out, and what digging the job up would actually involve, before anything gets booked in.
When excavation is the only option
Four situations push a job from repair into excavation, and they’re not equally common. A full collapse is the most obvious trigger and usually the most urgent: the pipe’s caved in on itself, water has nowhere to go, and there’s nothing left inside for a liner to seat against. Deformation sits a step behind that, and it shows up often in older Glasgow tenements, where clay pipework has sat under a driveway or a back court for the best part of a century: the pipe hasn’t collapsed outright, but ground movement or the weight above it has squashed it oval, and a liner fed through an uneven, out-of-round bore won’t cure properly. The third case is harder to spot on a first look, because the damage builds up gradually rather than showing as one obvious defect: a run affected by old root ingress, several previous patch repairs, or corrosion can end up with so little sound pipe wall left that there’s nothing for a new liner to bond to. Relining depends on the host pipe holding its shape and giving the resin something to adhere to. Where that structure has gone, lining it stops being an option no matter how the rest of the survey reads. The fourth case is a new pipe run rather than a repair at all: for an extension, a rerouted drain, or a connection that never existed before. There’s no old pipe involved, so relining was never on the table for this one.
How the survey decides it, not us
We don’t decide a drain needs excavating over the phone, and we’d be wary of any company that did. The call comes out of a CCTV drain survey, run before any repair gets quoted, that shows exactly what’s wrong and how much sound pipe is left to work with. If the pipe’s still holding its shape, pipe relining gets tried first: it’s quicker, it doesn’t touch the surface above the drain, and for most defects it does the job. Excavation only gets recommended once the footage rules that out.
The wider repair options, relining, patch repairs, and root cutting, are covered on the drain repairs page. This page picks up specifically where those options run out.
What a drain excavation job actually involves
An excavation job follows a sequence, and skipping a step is how gardens end up dug up twice.
Finding what’s already in the ground
Before anything gets dug, we check what else is running through that patch of ground. Gas, water, electricity, and telecoms cables all sit at different depths near a drain run, and a mains service struck by an excavator is a bigger problem than the blocked drain that started the job. We check utility records first and get any live services marked out on the ground before a spade goes anywhere near it, and anything found running close to the dig gets hand-dug or carefully exposed rather than machine-excavated blind.
Trenching and spoil
The trench itself is kept as narrow and as short as the repair allows, following the line the camera has already mapped rather than opening up more ground than the job needs. Spoil, the material dug out of the trench, gets stacked on boards or sheeting rather than piled straight onto a lawn or path. Boards and sheeting protect the surface underneath, and keeping the spoil contained matters for a second reason: it isn’t always suitable to go straight back into the hole once the new pipe’s in.
Pipe bedding and gradient
A new pipe needs a bed of granular material underneath it, evenly compacted, so it’s supported along its whole length rather than resting on a few high points that would crack it again in time. Gradient matters just as much as the bedding: a foul, surface water, or combined drain (common across Glasgow’s older streets, where the two run in the same pipe) relies on a steady fall toward the next manhole or inspection chamber to keep waste moving by gravity alone, and a pipe laid too flat, or with even a slight dip in it, will silt up and start blocking again within months, no matter how new it is.
Backfilling
Once the new pipe is in and tested, backfill goes back in around it as a series of compacted layers, each one tamped down before the next goes on top. Filling a trench in one go around a new pipe risks leaving voids that settle later, which is the same kind of ground movement that damaged the old pipe in the first place.
Surface reinstatement
What goes back on top depends on what was there to begin with, and paving is what we deal with most often across Glasgow driveways and back courts. Block paving gets lifted block by block before the dig starts, kept in order, and relaid using the original blocks wherever they’ve survived, so the pattern lines up rather than leaving an obvious repaired strip running through it. Tarmac gets the same care for the same reason: cut back to a straight edge and reinstated to match the existing depth and finish, rather than patched roughly over the trench line. Lawns and concrete tend to be more straightforward. Turf gets relaid or the area reseeded once the ground has settled, and a concrete section is broken out cleanly and re-poured to tie into the surrounding slab. None of it gets rushed, because a reinstated surface that sinks or cracks within a year means the same disruption happening twice.
For an idea of what a specific job would involve, call 0141 673 3535 with the survey findings to hand if you have them, and we’ll talk through the practical side while it’s still at the planning stage.
Permits, notifications, and working near a public sewer
Not every excavation needs sign-off beyond the property boundary, but some do. Where a drain run sits near, crosses, or connects into a public sewer, Scottish Water has an interest in the work, because a public sewer stays part of the network even where it runs under private ground, and the utility needs to be able to access and maintain it later.
Build-over consent is the main one to know about. If the drain sits under, or close to, a planned extension or an existing structure, Scottish Water’s consent is needed before work goes ahead, and excavating without it can complicate a later consent application rather than solve the problem. Where a job also needs a fresh CCTV survey for a consent file, that’s something we provide alongside the repair itself, whether the application’s being handled by you, your builder, or your solicitor.
For most straightforward domestic jobs (a driveway, a back garden, a single damaged section well away from any public sewer) none of that Scottish Water process applies, and we get on with the work. It becomes relevant on bigger jobs, jobs near a boundary, or anywhere an extension or new building is planned over or near the drain run.
Excavation across Glasgow and North Lanarkshire
Excavation looks different depending on where in Glasgow it’s happening, mostly because of what’s on the surface rather than what’s under it. Tenement back courts in the West End and Southside often have shared drainage running under decades of paving, sometimes serving two or three flats off the same run, so before any digging starts we work out who’s responsible for the section involved, whether that’s an individual owner, a landlord, or the close’s factor, and what else is under that surface: bin stores, shared bike sheds, and old paving laid in phases that doesn’t always match what’s on record.
Newer estates on the edges of the city, and further out into Coatbridge and Airdrie in North Lanarkshire, tend to be more straightforward: modern pipework laid to current standards, clearer access, and driveways or turfed gardens that reinstate cleanly. Commercial premises sit somewhere in between. A yard or car park behind a restaurant, an East End trade unit, or a shop in the city centre can usually take a mini excavator without much fuss, but trading hours matter more than the ground does, so excavation at a commercial site tends to get planned around closing times or quieter trading periods rather than squeezed into a single working day regardless of what’s happening inside.
For more on how we run a job from the first phone call through to sign-off, the Glasgow drainage company page has the detail.
Book a drain excavation survey
Excavation only gets recommended once a CCTV survey has shown there’s no better option, so the first call is really a survey booking. Phone 0141 673 3535 and tell us what’s prompting the concern, whether that’s recurring blockages, visible ground movement, or a survey report you’ve already had done elsewhere, and we’ll take it from there.
If you’d rather send the details than call, get in touch and we’ll come back to you with next steps.
