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TWIRLS: Treating Waste for Restoring Land Sustainability

Shotton site diary

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Begins in January 2006........

23 - 26 January

Sue and Mark spend the week measuring and marking out plots for the large vegetation establishment experiment on the site of the former Shotton steelworks that has been bare for some 15 years. The site is close to the Dee estuary and consistently about 5 degrees colder than our cosy offices in Bangor. The aim of this experiment is to test the suitability of 6 different composts produced last year (using EcoPOD in-vessel composters) for creating a species rich meadow grassland on this sandy site. We're trying 6 different composts at 3 different rates of application and including un-seeded plots to see what species will establish naturally. With each different treatment replicated 6 times (to make a statistically valid experiment) we have 216 plots to mark out and create a small forest of wooden stakes.

The bare former steelworks site at Shotton ready for spreading.

We're also marking out plots to receive soil from the site that has been co-composted with organic wastes. The soil was contaminated with low to moderate levels of organic pollutants from the old steelworks and the microorganisms responsible for breaking down organic matter during composting will have transformed most of these pollutants into harmless products, carbon dioxide and water. We will also study the fate of any remaining pollutants once the composts have been spread and see whether levels fall further when the plots are planted either with black poplar (Populus nigra) or sown with a meadow grassland mixture.

27 - 31 January

The plots are finally marked out (phew) and we get our friendly contractors on site to help us spread the composts using agricultural machinery. We want to apply compost at 3 different rates to see how the different amounts of nutrients (nitrogen, phosphorus etc.) will affect the establishment of meadow plants and the diversity of plant and insects. It takes a while to work out how to achieve the different application rates, by varying the speed at which the tractor tows the spreader across the plots, but we get it right in the end. The spreading is inevitably a little patchy so needs neatening up with shovels and rakes.

Sue is happy with her handywork!

3 February

We finish spreading the composts and the experiment looks impressive from the main road. Now we need to wait until the weather warms up before we can seed the plots with our meadow grassland mixture. Our loggers recorded temperatures as low as minus 9 degrees centigrade at night and temperatures rarely got above 4 degrees all week.

The spread plots need to be sown with meadow grassland mixture now.

6 March

We need to make more compost for spreading around the perimeter of the site as part of the larger demonstration planting. We plan to compare 2 in-vessel composts vs windrow compost vs un-composted wastes and we' also like to assist UPM-Kymmene (who own the site) by making some compost for use in a short rotation willow coppice planned for the other end of the site from our trials. We arrive on site to meet the contractors bringing the EcoPOD filling machine but snow brings everything to a halt as the feedstock materials are too wet and there's a chance that the compost would go anaerobic (not enough oxygen) and begin to produce methane. We play in the snow instead!

Mark in the snow at Shotton.

9 March

The snow has mostly melted and we have the wastes (de-inking paper pulp, shredded green waste, tertiary treated sewage cake) for composting delivered to our site and begin to mix the wastes and load the composting vessels. Once in the bags and connected to the aeration fans the composting process begins and the temperature of the compost reaches 75 degrees centigrade. We sit on the steaming bags of compost to keep warm!

Our cold wet composting site at Shotton.

18 May

After frantic preparations we hold an open day on-site. Approximately 30 people, including Environment Agency officers, representatives of Flint CC, the Welsh Assembly Government and the European Union witnessed a fine demonstration by Rhidian and Jon, of the process of loading EcoPOD composting vessels in the sunshine. Visitors then toured the meadow grassland establishment and bioremediation trial sites before heading across to Shotton Paper Mill for lunch and a Q & A session.

Visitors enjoying a demonstration of in-vessel composting at our on-site open day in May 2006.

Touring the meadow grassland establishment trial site.