Spray washing disposal trial shows promise
Spray washing disposal trial shows promise
BIOBEDS to dispose of excess spray and sprayer washings could be the answer to ground water regulations which come into force at the end of March.
At Morley Research Centre in Norfolk one of three experimental biobeds was established last autumn. "Basically it is a lined hole in the ground of a pre-determined size," says Morley farm manager, Andrew Thurston.
The sloping sided hole has an impermeable sheet lining and is filled with a mix of 50% straw, 25% soil and 25% peat or peat substitute.
A 23cm (9in) perforated pipe is laid down the middle of the pit to monitor water level and grass planted on top.
"The idea is that grass will remove the water by evapotranspiration, microbes in the biobed break down the active ingredients and the peat helps absorb the residues," says Mr Thurston.
For the 302ha (746 acres) of arable crops near to the main farm at Morley, Mr Thurston calculates 16,000 litres of washings a year will be produced, split between 7000 in the autumn and 9000 in spring and early summer.
Silsoe Soil Survey researchers who are running the project reckon a 1.8m deep, 8m square pit should cope with that volume.
But heavy rain this autumn filled the bed to capacity. "We have had to put a cover over it to stop any more rain getting in," says Mr Thurston.
At Morley it will be fenced off, though it is not yet clear whether this is necessary under designated contaminated area requirements. "Even when saturated the surface of the bed is firm and could be walked on.
"If this system works it will be a good way of disposing of washings, and it only cost about £1000 to build. It is not a case of watch this space, rather watch this hole," Mr Thurston concludes.
Biobed Detail
• Washing volume a year sets size
• Sloping sides, impermeable liner.
• 50% straw, 25% peat/peat substitute, 25% soil fill
• Grass over top.
• Cost effective alternative to Environment Agency licence for disposal.
BIOBED DETAIL
• Sloping sides, impermeable liner.
• 50% straw, 25% peat/peat substitute, 25% soil fill
• Grass over top.
• Washing volume a year sets size
• Could be cost effective alternative to Environment Agency licence for disposal.