SiteSafety

No — these are classed as confined spaces and can contain lethal concentrations of hydrogen sulphide, methane and low oxygen levels, even after emptying. Entry should only be carried out by trained operatives with gas detection equipment, breathing apparatus and a permit-to-work system in place. For routine inspection, use the designated inspection ports rather than opening the main access chamber.

This depends on where the cover sits: A15 (1.5 tonne) is typically fine for pedestrian-only areas like gardens, B125 (12.5 tonne) suits driveways with car traffic, and D400 (40 tonne) is required for roads or areas accessed by heavy vehicles such as tankers. Fitting an under-rated cover is a genuine safety hazard and can lead to collapse, so always specify load rating based on actual site traffic, not just tank position.

Trench collapse is the biggest risk, particularly in loose or waterlogged ground, so excavations should be properly supported or battered back in line with HSE guidance. Groundwater ingress can also cause tank flotation before backfilling is complete, which is why pea-shingle backfill and correct anchoring (or ballast, for some GRP models) matter. Always keep the excavation fenced or covered when unattended, and follow the manufacturer's installation instructions exactly — incorrect backfill is the most common cause of tank deformation or collapse.

Yes — an open excavation or an installed tank without its access cover fitted is a serious fall and entrapment hazard, especially where children, pets or the public could have access. Use secure edge protection, temporary fencing or full boarding over the opening whenever the site is left unattended. Once the tank is in and backfilled, lockable, load-rated access covers should go on immediately rather than being left until final commissioning.

Larger GRP and polyethylene tanks are usually fitted with integral ladder rungs or can have a fixed access ladder specified at order stage — check this before purchase if regular internal access will be needed. Never improvise with a freestanding ladder inside a tank, as the base can slip on wet or sludge-coated surfaces. Full internal entry should still follow confined space procedures, with ventilation running and a second person present at all times.

Confirm access routes are clear and firm enough for the delivery vehicle, and that there's adequate space to manoeuvre and lower the tank without it swinging into people or structures — most large GRP and polyethylene tanks need mechanical lifting, not manual handling. Check lifting points are used correctly, as tanks can crack or distort if lifted from the wrong points or with unrated straps. Keep non-essential personnel clear of the lifting zone throughout, and have the final position and supports ready before the tank arrives so it isn't left standing insecurely.