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Canal crossing guide
A pipe, duct or cable taken under a canal is consented, designed and drilled to a different set of rules from a river crossing. The canal is owned, water, bed, banks and a margin of land each side, by the Canal & River Trust, the consent is theirs, the depth expectation is far greater than the river rules ask, and the whole process is built around one risk, losing water from a channel that often sits above the land around it. This guide walks through how a canal crossing actually runs, stage by stage. Who consents, what the boreholes and bed survey are for, why the crossing sits around 3.5m below the bed, what the Works Engineer inspects, and what you hold at the end. It is written for whoever has to programme and pay for the crossing, and it assumes you have never crossed a canal.
The Canal & River Trust is the charity that took over the canal network in England and Wales from British Waterways, and unlike a river authority it is a landowner. Any third-party works affecting its property, and a crossing beneath the canal is exactly that, need its consent under its Code of Practice for Works Affecting the Canal & River Trust. The application goes through the Works Engineer at the local Trust office, and the Works Engineer stays with the job all the way through, advising on the crossing, reading the ground investigation, accepting the method statement, inspecting the pits and receiving the records at the end.
The Trust’s code presumes trenchless from the start. Open-cut through the canal is very unlikely to be permitted, an overhead crossing is not permissible at all, and crossings are normally perpendicular to the waterway, so a directional drill or another trenchless method is not the alternative option here, it is the expected one. The code’s stated principal criterion is leakage from the canal, and almost every requirement below, the depth, the pit setbacks, the grouting rules, the monitoring, traces back to that one concern.
If you have read our FRA3 river crossing guide, the numbers there do not carry across. There is no exemption to design to and no free registration. A canal crossing is consent from a landowner with a published technical code, the depth expectation is more than double the river figure, and the consent takes months rather than days. If you want the short version and a price, our canal crossings page is the place. This is the long version.
At a glance
| Stage | What it contains | Where the site information goes | What we need from you |
|---|---|---|---|
| 0 A canal is not a river | The Canal & River Trust identified as the owner and consenting body, the Code of Practice, the local Works Engineer | The crossing location tells us which waterway and which Trust office | Where the crossing is, what is going in it, your dates |
| 1 Early engagement | The Works Engineer contacted, the early site visit, the notification and the Trust’s consent process started, the lead time in the programme | Anything already held on the site goes in early | Who the scheme is for, the notification made in good time |
| 2 The site investigation | A minimum of two boreholes, one each side, with laboratory testing, the bed survey, the full-width depth profile drawing | The water depth, the silt, the hard bed level and the ground the bore runs through | Access to the land each side, your decision on any investigation beyond the minimum |
| 3 The crossing design | The depth of the order of 3.5m below the hard bed to the pipe crown, the impact assessment and settlement calculations, the pit positions, any sleeve or duct | The boreholes and bed survey become the long section, the depth and the calculations | Sign-off on the line and what is going in it, agreement on the pit positions |
| 4 Before site | The method statement addressing seepage and leakage accepted by the Works Engineer, the contingency plan for any fluid break-out, the inspection notices | Nothing new, the paperwork is finalised | The consent in force, land access each side, a named contact |
| 5 The works | Round-the-clock working once the bore starts, the depth and alignment monitored constantly, surface monitoring over the bore, the canal watched for leakage both ways | The drilling records, the monitoring readings, the grout records | Site access each day |
| 6 After | Permanent markers on both sides of the waterway, the as-laid drawing to the Works Engineer, the pits backfilled and reinstated, the condition survey repeated | Everything above, on the Trust’s record | Nothing, you receive it |
The figures on this page are from the Trust’s Code of Practice Part 2, and the Works Engineer can vary them for the ground and the method, in either direction. The Trust’s current process, lead times and fees are confirmed with the local Works Engineer at the start of every crossing.
Stage 0
The first thing to get right is who you are dealing with, because the rules for a canal are completely different from the rules for a river.
The Trust’s code presumes a trenchless crossing. Open-cut through the canal is very unlikely to be permitted, an overhead crossing is not permissible, and the crossing is normally perpendicular to the waterway. So the question is not whether to drill it, it is how deep, from where, and with what protections, which is what the rest of this guide covers.
| Where the site information goes | The crossing location tells us which waterway it is, which Trust office and Works Engineer look after it, and whether the canal sits on an embankment above the surrounding land, which shapes the whole design. |
|---|---|
| What we need from you | Where the crossing is, what is being installed and when you would like it in the ground. Each one is explained in this section. |
| Then | The right consent process is known from day one, with the Trust’s lead time in the programme honestly. |
Stage 1
The Trust strongly encourages contact with the Works Engineer before anything is designed, and it is genuinely worth doing, because the Works Engineer knows the waterway, its condition, its history and its sensitivities, and their early advice shapes the crossing before any money is spent drawing it.
| Where the site information goes | Anything already held on the site, surveys, service records, old crossing drawings, goes to the Works Engineer early, because their advice on the crossing starts from what is known. |
|---|---|
| What we need from you | Who the scheme is for, because the Trust’s consent and cost undertaking sit with the promoter of the works, and the notification made in good time. |
| Then | The site visit is held, the scheme is registered with the Trust, and the investigation can be scoped with the Works Engineer’s expectations known. |
Stage 2
On a canal the ground investigation is a requirement of the code, not a judgement call, and it is more prescriptive than most clients expect.
When the borehole logs and the bed survey are with the Works Engineer, they confirm whether the proposed method can be considered and whether the proposed depth is acceptable, and the depth given at this stage can still be adjusted for what the ground reveals later. The design waits for that confirmation rather than assuming it.
| Where the site information goes | The boreholes and laboratory results, the bed survey, and the drawing that puts them together, the water depth, the silt, the hard bed level and material across the full width of the canal. |
|---|---|
| What we need from you | Access to the land on each side for the borehole rig, and your decision on any investigation beyond the minimum two holes. |
| Then | The Works Engineer reads the logs and the bed survey and confirms whether the method and the proposed depth are acceptable. Then the design is done against ground that is known, not assumed. |
Stage 3
The design is where the canal regime shows how differently it thinks from the river one, and the depth is the headline. The code’s figure for a trenchless crossing is a minimum depth to the crown of the pipe of the order of 3.5m below hard bed level, the firm bed beneath the silt, varied as necessary by the Works Engineer for the ground and the technique. That is the starting expectation, not a target to negotiate down from, and it is confirmed against the borehole logs and the bed survey rather than assumed.
| Where the site information goes | The boreholes and the bed survey become the geological long section, the depth to the pipe crown and the impact assessment, with every structure in the zone of influence, walls, weirs, culverts and locks, considered. |
|---|---|
| What we need from you | Your sign-off on the line and on what is going in it, and agreement on where the pits sit, because the setback from the water’s edge and the level above the canal are requirements of the Trust’s code. |
| Then | The design goes to the Works Engineer with the calculations behind it, and the method statement is written from it. |
Stage 4
The Trust’s consent to start follows the paperwork, and the paperwork is built around the water.
| Where the site information goes | Nothing new. The method statement carries the seepage and leakage controls, the contingency plan for any break-out of drilling fluid, and the pumping and grouting arrangements the Trust expects. |
|---|---|
| What we need from you | The consent in force, the land access in place on each side, and a named contact for the works. |
| Then | The Works Engineer’s inspections are booked on 48 hours’ notice, and the rig arrives. |
Stage 5
A canal crossing is drilled the same way as any other, from a pit set back on one side, under the bed on the designed profile, to a pit set back on the other. What is different is the watching that goes on around it.
| Where the site information goes | The drilling records, the constant depth and alignment monitoring, the surface monitoring readings, the grout-take records and the fluid reconciliation. |
|---|---|
| What we need from you | Access to the pits and the compound each day. The works run round the clock once the bore starts, and we plan the site around that. |
| Then | Pipe in, with the canal, the towpath and the boats above it undisturbed. The last stage closes it out. |
Stage 6
The job ends the way the Trust’s code says it ends, on record and inspected.
| Where the site information goes | Everything above, closed out and on the Trust’s record, with the as-laid drawing lodged with the Works Engineer. |
|---|---|
| What we need from you | Nothing. You receive the record set. |
| Then | The markers stand on both sides of the waterway, so the next person to work near the canal knows the crossing is there. |
Months. Allow around 3 months from notifying the Trust to starting on site, with the site investigation, the Works Engineer’s review of the logs and the bed survey, and the design running inside that window. A crossing that would need the navigation closed needs far longer, allow around 12 months, which is one more reason the design keeps out of the channel. The works themselves are short, typically days, run round the clock.
Questions answered
The Canal & River Trust, the charity that owns the canal network in England and Wales, and that ownership runs to the water, the bed, the banks and a margin of land each side. Any third-party works affecting their property need their consent under their Code of Practice for Works Affecting the Canal & River Trust, applied for through the Works Engineer at the local Trust office, and the Trust strongly encourages an early site visit before anything is designed. The Environment Agency is not the consenting body for a canal, that is the river regime, and the two are easy to mix up.
Much deeper than a river crossing. The Trust's published expectation for a trenchless crossing is a minimum depth to the crown of the pipe of the order of 3.5m below hard bed level, the firm bed beneath the silt, and the Works Engineer varies it as necessary for the ground and the technique. Compare that with the 1.5m floor in the Environment Agency's river exemption and you can see how differently the two regimes think. The depth is confirmed by the Works Engineer after reading the borehole logs and the bed survey, not assumed.
Because a canal is a man-made channel holding its water above the surrounding ground in many places, and its principal risk is losing that water. Many canals are watertight because of a clay lining, and the Trust's own code says no impermeable lining should be assumed to exist, so the design treats the bed as vulnerable in both directions. Drilling fluid must not escape upwards into the canal, and canal water must not drain downwards through the bore into the pits. That is why the pits are set back at least 5m from the water's edge, kept off any embankment, and raised at least 300mm above the maximum canal water level, so any water that did find the bore is contained, and where the ground levels cannot give that, a bund is built around the pit to give the same protection.
Allow around 3 months from notifying the Trust to starting work, and around 12 months where the works would need the navigation closed, with a towpath closure needing about 4 weeks' notice. The site investigation and the design run inside that window, so on a typical crossing the Trust's process and ours run in parallel rather than one after the other. The current lead times and fees are confirmed with the local Works Engineer at the start, because they are the Trust's to set.
Yes. The Trust's code requires a site investigation with a minimum of two boreholes, one on each side of the canal, with laboratory testing to verify the strata, taken to a depth agreed with the Works Engineer and at least 3m below the anticipated invert of the crossing. It also asks for a drawing showing the depth profile across the full width of the canal, the water depth, the silt, and the level and material of the hard bed, tied to Ordnance Datum and to the canal's own weir level. The Works Engineer reads the logs and the bed survey before confirming the method and the depth, so the boreholes are not optional and they are not a formality.
The contingency is agreed before the bore starts, and it is built around protecting the canal. A contingency plan with containment strategies for any break-out of drilling fluid is in place, the depth and alignment are monitored constantly, and if canal water appears in a pit or the bore, whatever action is necessary is taken immediately and the Works Engineer is informed before work continues. If a bore proves abortive, work does not resume until the Works Engineer has accepted alternative proposals, and the abandoned pipe stays in position and is grouted up along with any overbreak, so no void is left near the canal.
No, and the two are easy to mix up. A river crossing runs through the Environment Agency and normally qualifies for the FRA3 exemption, a free registration with a 1.5m minimum depth condition. A canal crossing runs through the Canal & River Trust, with consent through their Works Engineer, a depth expectation of the order of 3.5m to the pipe crown, boreholes as a requirement, round-the-clock working, and a lead time measured in months. Our FRA3 river crossing guide walks the river regime the same way this page walks the canal one, and if your route crosses both, both processes run.
Related
The short version, what the Trust asks of a crossing, what we handle, and a price.
Read more →The river regime walked the same way, the Environment Agency exemption and the crossings designed to it.
Read more →The bore profile, long section and settlement calculations behind a canal crossing.
Read more →Send us the waterway, the service and the line you want, and we will tell you what the Trust will ask for, what the crossing needs, and what it is likely to cost.