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FRA3 river crossing guide
A pipe, duct or cable taken under a river is controlled by the Environment Agency, and a trenchless crossing normally qualifies for the Agency’s FRA3 exemption, which turns a two-to-four-month permit application into a free online registration made before work starts. This guide walks through how that actually runs, stage by stage. The check that is done first because it can force the permit route on its own, where the bed survey and the ground investigation go, why the crossing is drilled far deeper than the exemption asks, who registers it, 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 river.
The Environment Agency controls work in, under, over or near a main river, the larger rivers and streams it shows on its main river map. You are in its territory if the work comes within 8m of the bank of a non-tidal main river, or 16m if the river is tidal, with the same distances around flood defences and culverts, and 16m around a sea defence. A service crossing below the bed of a main river is a flood risk activity, and it would normally need a full Flood Risk Activity Permit.
The exemption changes that. FRA3 covers a service crossing below the bed of a main river that does not use an open-cut technique, which is exactly a trenchless crossing, drilled or rammed. Meet every one of its conditions and the crossing is a registrable exemption, free, registered online before work starts, with no determination period, so it does not sit on the programme at all. So the whole job is designed around staying inside the conditions, and the stages below are that design done in the right order.
If you have read our CD 622 guide for a National Highways road or our UTX guide for a railway, this regime is different in kind. There is no chain of submissions, no independent checker and no certificate. The Environment Agency does not review your design at all on the exempt route, it publishes the conditions and expects the crossing to meet them. That puts all the effort at the front. The buffers are checked before anything is designed, the bed is surveyed so the depth is measured from the actual riverbed, and the crossing is designed to meet every condition before it is registered. If you want the short version and a price, the river 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 What are you crossing? | The main river map checked, the right consenting body identified, the 8m and 16m engagement distances and any local byelaws confirmed | The crossing location decides who consents and which rules apply | Where the crossing is, what is going in it, who the scheme is for, your dates |
| 1 The early protected-site check | The protected-site buffers checked against the crossing location, 200m to designated conservation sites, 100m to high morphological status water | The location is run against the designated-sites mapping | Nothing, we run the check from the location |
| 2 The surveys | The topographical survey of the banks, the bathymetric survey of the bed, ground investigation where the design needs it | The bed profile and the hard bed level the depth is designed against, and the ground conditions | Access to the land on each bank, anything you already hold on the site |
| 3 The crossing design | The bore designed to meet every FRA3 condition, with the depth set from the drilling design rather than the 1.5m floor | The bed survey and the ground investigation become the long section and the depth | Sign-off on the line and what is going in it, agreement on where the pits sit |
| 4 Registration, or the permit | The exemption registered online before work starts, free with no determination period, or a full permit application where a condition cannot be met | The crossing design shows the conditions are met | Who registers settled, you, the asset owner or us |
| 5 Before site | RAMS with the frac-out and inadvertent-returns plan, inert additives, containment and clean-up kit on site, a stop-work-and-notify trigger | Nothing new, the paperwork is finalised | Land access agreed on each side, a named contact |
| 6 The works | Pits set back from the bank, drilling fluid pressure and returns monitored continuously, a visual watch on the water, the bed and banks untouched | The drilling records and the fluid monitoring | Site access each day |
| 7 After | Permanent hazard markers on both banks, surplus excavated material removed from the flood plain, the as-built record | Everything above, on record | Nothing, you receive it |
FRA3 covers any crossing that does not open-cut the river, so everything below applies to a directional drill and to a rammed casing alike. The figures are England’s. Wales runs the same regime under Natural Resources Wales, Scotland is a different system, and both are covered at the end of the page.
Stage 0
The first question is not how to cross the water, it is what the water is in law, because that decides who consents and which rules apply. Three answers are possible.
For a main river, the engagement distances matter from the start. The Environment Agency’s interest is triggered by any activity within 8m of the bank of a non-tidal main river, or 16m if it is tidal, and the same distances apply around flood defences and culverts. Those are the national defaults, and local flood-defence and land-drainage byelaws can set different or additional distances, so the byelaw distances for the specific site are confirmed with the Agency rather than assumed.
| Where the site information goes | The crossing location is checked against the Environment Agency’s main river map, which decides whether the Agency is involved at all, and against any local flood-defence byelaws, which can change the distances. |
|---|---|
| What we need from you | Where the crossing is, what is being installed, who the scheme is for and when you would like it in the ground. Each one is explained in this section. |
| Then | The regulator is known, the distances are known, and the crossing can be checked against the protected-site buffers before any money is spent on design. |
Stage 1
Before any design is done, the crossing location is checked against the protected-site buffers, because these can force the full permit route on their own, no matter how well the crossing is designed. The exemption does not apply if the activity is:
These are buffers around designated sites, not judgements about the crossing, so a perfectly designed bore 150m from an SSSI still cannot be registered as exempt. Protected sites are common along river corridors, which is why this is checked first. It costs nothing to run the check from the crossing location, and the answer sets the route for the whole job. Clear of the buffers, the crossing is designed to the exemption and the programme carries no approval time at all. Inside them, the permit route is known from day one, the 2 to 4 month determination window goes into the programme honestly, and the pre-application discussion with the Environment Agency starts early.
| Where the site information goes | The crossing location is run against the designated-sites mapping, the conservation sites and the morphological status of the water. |
|---|---|
| What we need from you | Nothing. We run the check from the location, and it costs you nothing to find out early. |
| Then | Clear of the buffers, the crossing can be designed to the exemption. Inside them, the permit route is known from day one and the programme carries it honestly. |
Stage 2
The exemption is measured from the riverbed, so the crossing cannot be designed until the bed is known. Two surveys do it, and a third joins them where the design needs it.
On a deep, wide or scour-prone river the bed also moves, and the Environment Agency may set the required cover from a calculated maximum scour level rather than the existing bed. The bed survey is what that conversation is had over, which is another reason it comes before the design.
| Where the site information goes | The topographical survey of the banks and the bathymetric survey of the bed give the bed profile and the hard bed level the depth is designed against. Any ground investigation tells the design what the bore will be drilled through. |
|---|---|
| What we need from you | Access to the land on each bank for the survey work, and anything you already hold on the site, a survey, borehole logs, service records. |
| Then | The design has a bed to be below and ground to be designed for. On to the crossing itself. |
Stage 3
The design has two jobs. It makes the crossing safe to drill and sound for the long term, and it proves, condition by condition, that the crossing qualifies for the exemption. To register the crossing as exempt, all of these have to be met:
The 1.5m is easy to misread. It is the threshold to qualify for the exemption, a regulatory floor, not the depth the crossing should be drilled to. Drilling at 1.5m below the bed leaves very little ground over the bore, and that invites the very things the crossing exists to avoid, settlement or heave disturbing the bed, and frac-out, where the drilling fluid breaks out to the surface because the shallow cover cannot contain the pressure in the bore. So the depth is set from the drilling design, not from the exemption. In practice that means typically more than 3m below the hard bed, and deeper again as the pipe size goes up, because a larger bore needs more ground over it to stay stable and to keep the fluid safely contained. The exemption depth and the design depth are two different numbers, and the crossing is drilled to the design depth, which satisfies the 1.5m comfortably as a by-product.
| Where the site information goes | The bed survey and the ground investigation become the geological long section, the depth and the bore profile, with every FRA3 condition designed in from the start. |
|---|---|
| What we need from you | Your sign-off on the line and on what is going in it, and agreement on where the launch and reception pits sit, because the setback distances are part of the exemption. |
| Then | The crossing meets the conditions on paper, provably, and the registration can be made on the strength of it. |
Stage 4
With the design proving the conditions, the crossing is registered as an exempt flood risk activity, online, before work starts. The registration is free and mandatory, and there is no determination period, so it does not hold up the programme. That is the whole point of the three stages before it.
Who makes the registration is worth settling deliberately. We can include it, and the crossing design that stands behind it is ours either way. In practice, though, it is often the asset owner or the main contractor who registers, because they are usually the ones in control of the legal side of the scheme, the easements, the landowner agreements and the consents that sit around the crossing, and the registration belongs naturally with them. The same goes for a permit application. What matters is that it is decided here, by name, so the crossing does not arrive at mobilisation with each side assuming the other had done it.
Where a condition cannot be met, the pits forced too close to a bank, the alignment more than 10 degrees off, a buffer in play, the crossing needs a full Flood Risk Activity Permit instead, either a standard rules permit or a bespoke one. That is a determination rather than a registration. The Environment Agency normally decides within 2 months for a flood-risk-only application, or 4 months where it is combined with other activities or goes to public consultation, and there is an application charge. We hold a pre-application discussion with the Agency, build the window into the programme, and provide the supporting design whoever makes the application.
| Where the site information goes | The registration itself is short. It is the crossing design behind it that shows the conditions are met. |
|---|---|
| What we need from you | A decision on who registers. We can include it, but it is often the asset owner or the main contractor who takes it out, because they usually control the legal side and the easements. |
| Then | Registered, the crossing can start straight away. On the permit route, the Environment Agency’s decision window sits in the programme first. |
Stage 5
Any release of drilling fluid into a watercourse is a pollution incident and an offence, even though bentonite is an inert clay, because it raises turbidity and can smother the bed. So the method statement for a river crossing is built around the water, and the Environment Agency expects to see, as method-statement conditions:
These controls are part of how we always work near water. The RAMS carry them, along with the working areas, the pit setbacks from stage 3 and the access arrangements each side.
| Where the site information goes | Nothing new. The method statement carries the frac-out and inadvertent-returns plan, the fluid monitoring arrangements and the clean-up kit the Environment Agency expects near water. |
|---|---|
| What we need from you | The land access in place on each side, and a named contact for the works. |
| Then | Rig on site. |
Stage 6
The crossing is drilled from a launch pit set back on one bank, steered below the bed on the designed profile, and received in a pit set back on the far side. Nothing is dug across the river, nothing enters the channel, and the bed and banks are left exactly as the exemption requires, undisturbed.
| Where the site information goes | The drilling records, the fluid pressure and returns monitoring, and the pilot bore survey that proves the depth below the bed. |
|---|---|
| What we need from you | Access to the pits and the compound each day. |
| Then | Pipe in, with the river untouched above it. The last stage closes it out. |
Stage 7
Three of the exemption’s conditions live at the end of the job rather than the start, and they are built into the method so they cannot be forgotten.
| Where the site information goes | Everything above, on record, with the as-built line and level of the installed crossing. |
|---|---|
| What we need from you | Nothing. You receive the record set. |
| Then | The hazard markers stand on both banks, so the next person to work near the river knows the crossing is there. |
In Wales the regime is the same, run by Natural Resources Wales under the same regulations, with the same 8m and 16m distances. Scotland is different. SEPA works to the Controlled Activities Regulations, a tiered system of its own, so the figures on this page do not carry across, and we check the SEPA rules for a Scottish crossing.
A canal crossing runs through the Canal & River Trust rather than the Environment Agency, with its own consent, far greater depth expectations and its own lead times, and it has its own walk-through in our canal crossing guide. If your route crosses a river and a canal, both processes run, each with its own authority.
On the exempt route, the approval itself takes no time at all, unlike a highways or rail crossing, where the approvals set the programme. Here the programme is set by the survey and design work at the front, the bed survey, any ground investigation and its laboratory testing, and the crossing design, which is typically weeks rather than months, and by ordinary site logistics. The registration is made before work starts and costs the programme nothing. The permit route is the exception, 2 months for a flood-risk-only determination and up to 4 where it is combined or consulted on, which is exactly why the buffers and the conditions are checked in stage 1 rather than discovered late.
Questions answered
Usually, yes. The Environment Agency controls work in, under, over or near a main river, the larger rivers and streams shown on its main river map, and a service drilled beneath the bed of one is a flood risk activity. The good news is that a trenchless crossing normally falls under the Agency's FRA3 exemption, so instead of a full permit application it is a free online registration made before work starts, with no determination period. The whole of this guide is about designing the crossing so it qualifies.
FRA3 is the Environment Agency exemption for a service crossing below the bed of a main river that does not use an open-cut technique, which is exactly a trenchless crossing. Meet every one of its conditions, at least 1.5m below the bed held for 5m beyond each bank, the bore within 10 degrees of perpendicular to the flow, the pits 8m from the bank or 16m if tidal, clear of banks, culverts, defences and impoundments, clear of the protected-site buffers, hazard markers on both banks, surplus material off the flood plain, the bed and banks undisturbed, and the crossing is a registrable exemption rather than a permit. Miss any one of them and it is not.
We can include it, and we do the crossing design that proves the conditions either way. In practice, though, it is often the asset owner or the main contractor who makes the registration or takes out the permit, because they are usually the ones in control of the legal side of the scheme, the easements, the landowner agreements and the consents that sit around the crossing. It is settled early, at the registration stage, so nobody discovers on mobilisation day that each side thought the other had done it.
Deeper than the exemption asks. The 1.5m in FRA3 is the threshold to qualify, a regulatory floor, not a design depth. Drilling at 1.5m below a riverbed leaves very little ground over the bore, which invites the very things the crossing exists to avoid, the bed disturbed by settlement or heave, and frac-out, where drilling fluid breaks through to the surface because the shallow cover cannot contain the pressure in the bore. So we set the depth from the drilling design, typically more than 3m below the hard bed, the firm bed beneath the silt, and deeper again as the pipe size goes up, and the 1.5m condition is satisfied comfortably as a by-product. On a deep, wide or scour-prone river the Environment Agency may set the required cover case by case, along with the datum it is measured from, and we confirm both before the bore is fixed.
Then it needs a full Flood Risk Activity Permit instead, either a standard rules permit or a bespoke one. That is a determination rather than a registration, so it takes time, normally decided within 2 months for a flood-risk-only application, or 4 months where it is combined with other activities or goes to public consultation, and there is an application charge. It is not a dead end, plenty of crossings go this way, it just has to be known early so the window sits in the programme, with a pre-application discussion held with the Agency. What must not happen is finding out late, which is why the buffers and the conditions are checked at the start.
A watercourse that is not designated a main river is an ordinary watercourse, and it sits outside the Environment Agency's river permitting altogether. A crossing there needs ordinary watercourse consent, sometimes called land drainage consent, from the lead local flood authority, the county or unitary council, or from the local internal drainage board where there is one. We design every watercourse crossing to the FRA3 conditions regardless of who consents it, because it is a proven standard for keeping the crossing well clear of the channel.
A canal runs to a different set of rules. It belongs to the Canal & River Trust, the consent is theirs rather than the Environment Agency's, the published depth expectation is far greater, and the process runs through their local Works Engineer with its own forms and lead times. It has its own walk-through on our canal crossing guide.
Wales, yes. Natural Resources Wales runs the same regime under the same regulations, with the same 8m and 16m distances. Scotland, no. SEPA works to the Controlled Activities Regulations, a different system with different tiers, so none of the figures on this page carry across, and we check the SEPA rules for a Scottish crossing.
Related
The short version, the FRA3 conditions we design to and the crossings behind them.
Read more →Our river, estuary and canal crossings, and the real jobs behind them.
Read more →The bore profile, bed survey and crossing design that prove the FRA3 conditions.
Read more →Send us the watercourse, the service and the line you want, and we will run the early checks, tell you which route your crossing is on, and come back with the design and a budget price.