On this photo of my wash plant, you can see the raceway sluice coming out from underneath the screening plant.
I like this configuration of a four foot wide sluice elevated a bit for easy cleanup. The majority of our gold is always found here. I have found that the ten foot length works pretty well for us.
The distribution box at the end of the raceway evenly spreads the discharge to additional eight foot wide by twenty foot long sluices with expanded metal riffles and miners moss underneath. The raceway sluicebox can use either expanded metal riffles or angle iron riffles. Sometimes I use a combination of both it just depends on the type of deposit I am mining.
On projects that need additional recovery I like the gravel pump at the end of the bank of sluices for additional scrubbing of fugitive clay that resists attrition. Gravel pumps have a lot of violence in the impeller and this action really breaks down most clays. The gravel pump easily transports the fines to jigs or centrifugal recovery systems depending on the requirements. With Diamonds and sapphires rubber lined pumps and sweeps reduces fractures in both minerals.