Method Statement for Drainage Works — UK
Free UK drainage method statement template — foul, surface water and combined — aligned with Sewerage Sector Guidance (SSG), HSG47 services search and CDM 2015. Covers trench shoring, manhole connections and confined-space chamber entry.
UK (RAMS) example document — Two-Storey Rear Extension — 14 Birchwood Lane, Reading. Client: Mr & Mrs A. Whitfield (Private Client). Site: 14 Birchwood Lane, Reading, RG1 5JT. Scope: Construction of a two-storey rear extension (6.4m × 4.2m) to an existing semi-detached dwelling. Works comprise breaking out of existing rear elevation, trench-fill foundations to 1.0m, traditional cavity blockwork to first floor, pre-stressed concrete lintels, timber roof structure with natural slate finish, plus alterations to existing rear wall to form structural opening with rolled steel joist (RSJ 203×102 UB23). Works programmed over 9 weeks with a peak site team of 6 operatives. Hazards assessed: Manual handling — blocks, lintels, plasterboard, Working at height — independent scaffold & roof structure, Buried services strike during excavation, Collapse of excavation / trench wall, Hand-arm vibration (HAVS) — breaking out, drilling, Silica dust — cutting blocks, brick, concrete, Vehicle/pedestrian segregation — narrow domestic street.
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- Site-specific draft
- Drainage hazards baked in
- Ready for competent-person review
Built around recognised UK method statement structure — hazards, controls, sequence, PPE and sign-off. Ready for competent-person review.
Drainage work blends two of the most regulated activities on a UK site: excavation (with the unique risk of striking live foul or surface-water sewers) and confined-space entry (manholes and chambers). The Sewerage Sector Guidance (SSG, successor to Sewers for Adoption) sets the technical standard for any drainage destined for water-company adoption. The 2017 fatal incident in Cheshire — two operatives killed in a sewer chamber by hydrogen sulphide — is the case study every drainage MS should be written against. Atmospheric testing, rescue plan and forced ventilation are not optional.
When is it required?
Every drainage installation requires a written MS under CDM 2015. Sewerage Sector Guidance (Volume 1 - Design and Construction) and the relevant water company's specific addendum (e.g. Severn Trent's SfA8, Thames Water's adoption requirements) govern construction standards. For any connection to an existing live sewer, the asset owner (water company) requires a method statement and chamber entry plan submitted in advance. Confined-space entry into any chamber requires a permit under the Confined Spaces Regulations 1997, with atmospheric testing, forced ventilation and a written rescue plan as the minimum.
What a good one looks like
A strong drainage MS opens with the asset-owner adoption reference, the HSG47 services search (utility records + CAT-and-genny + trial holes), the trench support method (matched to depth and ground type), and a separate confined-space entry plan for every chamber. It names the lifting equipment for manhole covers and rings (typically a 3-leg gantry or excavator with chain block), the pipe bedding and surround spec (Type B granular, Class S concrete, etc.), the testing regime (air test to BS EN 1610, CCTV survey for adoption), and the reinstatement (HAUC SROH for highways). Atmospheric testing and rescue arrangements are named, equipment-by-equipment, in the confined-space section.
Drainage hazards & controls
The site-specific hazards a drainage MS must address, with the controls that take residual risk to an acceptable level.
| Hazard | Persons at risk | Controls | Residual |
|---|---|---|---|
| Trench collapse | Operatives in trench | Trench box / hydraulic shoring per depth; max unsupported depth per ground type; daily inspection per CDM reg. 22; spoil min 0.5m from edge | Low |
| Services strike | Operatives, public | HSG47 search: plans + CAT-and-genny + trial holes; permit-to-dig; hand-dig within 500 mm of any located service | Low |
| Confined space atmosphere (H₂S, O₂ depletion, methane) | Anyone entering chamber | Atmospheric test before entry and continuously during; forced ventilation; minimum two operatives + standby man; full rescue equipment (tripod, winch, escape sets) on site | Low |
| Falls into chamber / open trench | Operatives, public | Edge protection on all openings; covers replaced when not actively in use; warning tape & lighting; secure ladders for access | Low |
| Manual handling - pipes (110-225 mm clay/concrete, 25-80 kg) | Pipelayers | Mechanical lift (excavator + sling) into trench; two-person handling >25kg; never carry pipes by hand into deep trenches | Medium |
| Biological contamination from live sewage | Operatives in/near live sewer | Tyvek coveralls + nitrile gauntlets + face shield for any live-sewer work; hepatitis A + tetanus vaccinations current; wash station within 10m; cuts/abrasions covered before start | Low |
| Plant strike during dig & lay | Pipelayers, banksman | Banksman with continuous radio contact; exclusion zone for slewing arc; no operatives in trench while excavator is digging — only after support installed | Low |
| Drowning in flooded chamber / trench | Operatives | Sump + pump in trench; chamber assessed for surcharge risk; rainfall forecast checked; stop-work threshold for rainfall (10mm/hr) | Low |
Step-by-step sequence
- 1
1. Asset-owner approval & services search
Connection design approved by water company; HSG47 services search complete with marked-up drawing; permit-to-dig issued.
- 2
2. Set-out & trench excavation
Set out to drawing; excavate to depth in defined panels with trench box installed before any operative enters; daily CDM reg. 22 inspection.
- 3
3. Bedding & pipe lay
Type B granular bedding to spec; pipes lowered mechanically; jointing per manufacturer; line and level checked before haunching.
- 4
4. Backfill in layers
Surround per spec (granular or concrete); selected backfill in 300 mm layers compacted; reinstatement to HAUC SROH for highway crossings.
- 5
5. Chamber construction / connection
Manhole rings lifted with 3-leg gantry or excavator + chain block; channelling and benching per spec; connection to live sewer via approved fitting.
- 6
6. Confined-space connection
Permit-to-enter; atmospheric test (O₂, CO, H₂S, LEL); forced ventilation 10 min before entry; rescue tripod set; standby man at surface; max entry 20 min with continuous monitoring.
- 7
7. Testing
Air test to BS EN 1610 (LH air test); CCTV survey for adoption; results submitted to water company.
- 8
8. Handover
As-built drawing; CCTV report; test certificates; adoption application submitted to water company.
Real example — 120m of 225 mm foul drain, 1.8m depth, with chamber connection (Coventry)
A civils subcontractor in Coventry is installing 120 m of new 225 mm clay foul drainage at 1.8 m depth, connecting to an existing live 600 mm trunk sewer at a manhole on the next street. The MS opens with the Severn Trent adoption agreement reference and the HSG47 services search (gas main at 0.9 m, BT duct at 0.4 m, both located by trial hole and marked on the drawing). Trench support: Mabey LH 80 hydraulic trench box, installed by the excavator before any operative enters, max one panel ahead of the pipelaying. Pipes (225 mm clay, 65 kg each) are slung in mechanically — no manhandling. The chamber connection is a confined-space entry: permit issued, atmospheric test (Crowcon T4 4-gas) at surface before opening cover, again after 10 min of forced ventilation (fan + ducting to bottom of chamber), continuously during entry. Standby man stays at surface in continuous contact with entrant. Rescue tripod with winch and twin-line fall arrest is rigged before entry. Max entry duration 20 min, with full rotation. The new pipe is jointed into a saddle on the trunk sewer, tested to BS EN 1610 (LH air test, 25 mm head, holds 5 min), CCTV-surveyed and submitted for adoption. The MS runs to 14 pages with a separate confined-space entry plan, vaccination records and the temporary works register entry for the trench box.
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Common mistakes that get a drainage MS rejected
- ·No confined-space permit for chamber connections (a frequent HSE prosecution)
- ·Atmospheric testing once before entry, not continuously
- ·No standby man at the surface during chamber entry
- ·Pipe lay before trench support — operative in unsupported trench
- ·Skipping CCTV survey, then having adoption rejected
- ·Live-sewer connection without hepatitis A / tetanus check on the operatives
Frequently asked questions
Is a confined-space permit required for every manhole entry?
Yes — any chamber where atmospheric, drowning or engulfment hazards could be present is a confined space under the Confined Spaces Regulations 1997. Permit, atmospheric testing, forced ventilation and standby man are mandatory.
What is Sewerage Sector Guidance (SSG)?
The 2020 successor to Sewers for Adoption, setting the technical standard for any drainage destined for adoption by a water-and-sewerage company. The specific water company will have an addendum (e.g. Severn Trent SfA8, Thames Water adoption code).
Do operatives need vaccinations to work on live sewage?
Hepatitis A and tetanus are strongly recommended (Leptospira/Weil's disease is also a recognised risk). Vaccination records should be held in the operative file and checked before live-sewer work.
What pipe-bedding spec should the MS reference?
Type B granular bedding (10 mm pea gravel surround) is standard for clay and plastic pipes in most ground conditions. Class S concrete surround for heavy traffic loads. The MS must name the spec the works are designed to.
How is a new drain tested?
Air test to BS EN 1610 (low-head pressure test) before backfill, and CCTV survey before handover for adoption. The water company's adoption checklist will list any additional tests.
What about ecology — newts, water voles, badgers?
Where works affect a watercourse or known habitat, an ecology survey and licence may be required (Wildlife and Countryside Act 1981, Conservation of Habitats and Species Regulations 2017). The MS should reference any ecology constraints from the planning conditions.
Related method statements & RAMS
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