Pellet retention system, slotted bucket D1, Ø 395 mm at 325 mm depth

Full diameter, half the depth

D1 has the same Ø 395 mm as the C3 and a little over half its depth. It is the form for wide gully pots that are not deep, and for positions where a full bucket has to be lifted out by hand.

That second reason is underrated. A 70 l bucket full of wet sediment is a two-person lift or a job for equipment. A 40 l bucket in the same pot is often not. Where a site services its own gullies without lifting aids, the smaller volume is a practical advantage rather than a compromise.

When to take D1 over C3

Three situations, and only the first is about geometry.

Clear depth is limited. The pot takes the diameter but not 575 mm of depth. Then D1 is the only one of the two that fits.

Extraction is manual. The pot could take a C3, but whoever empties it does so by hand. A lighter full bucket gets emptied on schedule; a heavy one gets postponed.

The pellet load is modest. Where the drain sits away from the main handling area and collects little, 70 l of capacity buys nothing. The insert will need changing on condition long before the bucket fills.

Where none of those apply and the depth is there, C3 uses the same footprint better.

Technical data

Regulatory context. EU Regulation 2025/2365 sets obligations for operators handling plastic pellets, and Operation Clean Sweep is a voluntary industry programme. A retention system can support the measures a site puts in place. It does not, on its own, make a site compliant with either, and WINKLER does not certify compliance. What a scheme achieves depends on the full set of measures, the maintenance regime and the documentation behind it. Background is set out in the guide.

Questions about the D1 form

Same pot as C3, so why choose D1?

Depth, handling weight or a low load. If none of the three applies, C3 uses the pot better.

Can I start with D1 and change later?

Yes. The bucket is the durable part and the insert is the consumable. If the load turns out higher than expected, moving to C3 in the same pot is straightforward.

Does the shallower bucket fill faster?

With the same inflow, yes, by volume. Whether that matters depends on whether the bucket or the insert reaches its limit first, and on most drains it is the insert.