A growing demand for waste from all of our gardens; Horticultural hocus pocus is turning our green waste into something we can put back on our gardens. Amy Hunt reports.

Byline: Amy Hunt

TO THE untrained eye it may look like a series of piles of soil. But there is some natural magic going on beneath the surface. At Sandhills composting site in Newburn, things that the ordinary gardener in Newcastle throws away is turned into a useful product.

The contents of the brown garden waste bins belonging to 56,000 households in Newcastle are brought to Sandhills to be shredded and turned into compost.

Trucks weigh in when they enter Sandhills before depositing their load of grass cuttings, prunings and weeds into bays.

Workers pull out any obvious items which should not be in the bins, such as plastic or general waste.

Householders are asked to put into their bin only what grows in the garden. Cut flowers can also be put in, but no kitchen scraps.

Next the green stuff is fed through a big machine called a high-speed shredder so it can be cut up into smaller pieces. This will allow the waste to break down more easily into compost, as bugs and bacteria get to work.

Big logs or bits of trees are fed through a slow-speed shredder to be cut up, then the product is mixed into the green waste to create the right blend of compost.

This is because at different times of the year the blend of waste brought to the site can change. In the summer there will be more grass cuttings while in the autumn and spring more branches and prunings.

For good compost the right ratio of carbon and nitrogen is needed.

If there is too much of one the waste can give off a mighty pong, or simply will not be of the right quality.

Last year a wet and warm summer led to furiously growing grass and a stinky problem for the managers of Sandhills as the grass rotted down.

Following complaints from people living nearby 700 tonnes of green waste was taken away from the site to be spread on land at Northumberland farms, which sorted the problem out. Once the waste has been shredded and mixed it is laid out in the open air in piles called windrows.

It will be left there for eight weeks and turned regularly to keep the temperature and moisture levels right and to let the air get in while the bugs do their work.

Samples of the compost are taken to test for bugs like E.coli and salmonella and see whether plants will grow in it.

If the samples pass the test, it will allow the site to get its PASS 100 quality compost certificate which means the compost is no longer classed as waste, but as a product which can be widely sold on.

So far the site has passed all its tests and the council hopes to get the PASS 100 certificate soon.

Next the waste goes through a big sieve-like machine called a trommel to separate the finer compost from larger pieces of waste. Big items are put back through the process to be broken down further.

The compost is then left to mature for around four weeks before it is ready.

At the moment a lot of the product, called soil conditioner, is used for land reclamation. Last year 1,500 tonnes were sold to reclaim the former Lambton Coke Works in Houghton-le-Spring.

The product is also sold in small quantities to members of the public and landscape gardeners. But once the council gets PASS 100 they will be able to sell it more widely.

The idea is that the people whose gardens produced the waste will be able to reuse it to improve the soil on their land.

Terry Harnan, team leader for waste management, said: "It is great for mixing into clay ground for drainage or into sandy soil to improve water retention.

"The residents of Newcastle are creating it and we're encouraging them to use it as well." Out of all the waste which is brought to the site - 10,000 tonnes a year - less than 100 tonnes is wasted because of contamination.

But householders are still reminded not to put anything in the bins except garden waste.

Any woodchips brought to the site are kept separate so they can be sold on or used by the council as mulch on its gardens.

Bags of compost and woodchip can be bought for pounds 2 per 50-litre bag, or for pounds 10 a tonne loose.

Two years ago, in April 2007, Newcastle City Council launched a pilot of garden waste collection, rolling brown bins out to 15,000 homes in Newcastle.

Then in May last year brown bins were given to more households as part of the biggest ever shake-up of bin services in the city, where people were also given new wheelie bins for recycled waste.

Now garden waste is collected from 56,000 households, once a fortnight between March and October and once a month over the winter.

The collection service normally takes off after Easter as gardeners get outside to clear up after the winter.

Green waste from Newcastle's three household waste recycling centres, along with clippings from the council's parks and gardens service, is also brought to Sandhills.

A number of private contractors and landscape gardeners also take their waste to the site.

In total about 10,000 tonnes of green waste ends up at the site every year..

Sandhills Compost Facility

SANDHILLS is on Walbottle Road, Newburn.

The site is open to public and trade from Monday to Friday, 8am to 4pm.

Contractors and professional gardeners may tip-off their collected garden vegetation at Sandhills for composting.

Tipping charges apply. You will need to wear a high-visibility vest when on site.

Anybody, tradespeople or members of the public, can purchase soil conditioner and woodchip, either bagged or loose, from Sandhills. Logs are also available and delivery can be arranged.

. To contact Sandhills, call [phone]..

What to put in your brown bin: Yes:

Cut flowers from vases; Cuttings from larger shrubs and trees; Dead-headed flowers; Grass clippings; Hedge, shrub and bush trimmings; and leaves and weeds.

No: Branches or cuttings which are too long to fit in the bin or more than 10cm in diameter - they could damage the shredder.

Garden waste in plastic bags and sacks.

Sand, stones, rocks, bricks and paving Soil - you should knock it off the roots of plants before you put them in.

Turf - It's mostly soil.

Top Tip: Put two or three sheets of newspaper in the bottom of your bin to stop grass sticking to it..

CAPTION(S):

THE MIX A digger turns one of the compost heaps. GROWING DEMAND Above and below Sandhills site manager Terry Harnan with the finished product.