by TONY HOPKINSON
TOTAL CONTROL of the effluent process is the key benefit of an Archway weeping wall effluent system, says the company owner Matt Hodgson.
“The success of the Archway weeping wall system is that all material is totally contained until the liquid is sprayed and the solids are spread on suitable pasture or cropping ground,” says Hodgson. He and his wife Amanda own Archway Construction and its subsidiaries Archway Environment and Tri Block.
The whole weeping wall system can be built in no more than one week. Of modular design, its walls and ends are erected quickly, the floor poured and the outside backfilled. The concrete floor, the panels and the sealant between the panels are treated to withstand the corrosive effect of effluent.
Dairy News attended an open day on a farm with an Archway weeping wall. The Tauwhare, Waikato farm is owned by Trish and Paul Jones and has been sharemilked eight seasons by David van den Beuken and his partner Jenny Buckley.
The farm carries 540 Jersey and Jersey-cross cows, milking in a 36-aside herringbone dairy. Adjacent to the shed is a feedpad, 100m x 20m, that can hold 300 cows.
The farm’s milking platform is 170ha, flat to rolling and centrally raced to 80 paddocks with 50ha available for spray irrigation. The farm is a seasonal supplier to Fonterra.
Fonterra told the Jones three years ago that the farm’s effluent disposal system, largely dependent on spraying, no longer complied with co-op standards.
They began building a large holding pond to contain all effluent for spraying, but “something was telling us this option was not the best, so we called a halt to give us time to explore other options,” says Trish Jones.
The project was suspended for 12 months, during which they contacted Agfirst Engineering, Te Puke, dealing with Geoff Neilson. Agfirst designed and managed the building of the cowshed and effluent systems.
“We had special problems with this project because of the high-risk soils with impervious clay areas and low-lying areas prone to ponding,” says Neilson.
The solution was to install an Archway Construction weeping wall system that separates the solids from the liquids, the liquid green water transferring to a lined holding pond 45 x 45 x 3m with six weeks storage capacity. From there it is pumped back to holding tanks and used for flood washing the feedpad.
The surplus is pumped to pasture via a low application-rate spraying system.
“The big advantage on this site was that the shed is on a small hill, so gravity took the liquid all the way to the pond,” says van den Beuken.
Neilson told the field day audience of the need to build ‘future proof’ effluent systems rather than accept stop-gap solutions. Fonterra compliance rep Abigail Silvester endorsed this view, reminding the audience that the co-op has advisors to help suppliers get the right compliance advice.
The Archway weeping wall system has two parallel pits 39 x 6 x 1.5m.
“We believe each pit will only be cleaned every six months, just before the second pit is full, so it is very solid material,” said Archway’s Hodgson.
The pits are designed to be cleaned from either side by a 12t digger and the material dumped in an effluent trailer for spreading on pasture.
All speakers commented on the effluent’s fertiliser value and the resultant cost saving for farmers.
Each Archway weeping wall system comes with a free Hills Laboratory nutrient testing kit for testing raw effluent leaving the yard, solids nutrient content and the content of the spray. Farmers then know the value of the spread material and their compliance levels.
DairyNZ says one cow produces $25 of nutrients annually.