It was nicknamed the moon, a bleak, blackened landscape where nothing grew. But in a project under way on a former brickwork and tip site in Hednesford in the Midlands, a new recreational area is being created, with industrial units which should provide 650 jobs.
English Partnerships acquired 56 sites from the old non-operational British Coal portfolio, and Hednesford is one of three in the West Midlands. It transferred to EP in December 1996, though local authority Cannock Chase had for many years seen the site as a candidate for reclamation and regeneration, explains English Partnerships development manager Nick Bird.
That the project is possible at all is thanks to grant funding from the European Regional Development Fund, which is contributing up to £3.1M, which represents 42% of the cost.
Creating employment and improving the landscape are both prime aims of the project which covers a 33ha site. Over half the area will be landscaped with planting, water, footpaths and cycleways, while at the northern side two areas will be turned into light industrial estates covering a minimum of 8ha. Surrounding areas are residential, and both Beazer and Wilcon are building new homes adjoining the site and Hednesford Town Football Club is also a neighbour.
'The site has so many constraints, which is one of the reasons why you would never have got the private sector to have tackled it,' says Bird. 'The ERDF grant machine drives the project, because there are deadlines attached,' he adds. The key date by which a commitment had to be made was 31 December 1996, and the one for substantial completion is 31 December this year. 'It is important to achieve a minimum area of developable land,' he adds. 'We want to get receipts back into the public purse, to try and improve the value for money factor of the project.'
Halcrow was appointed by English Partnerships in June 1996, to work up the outline design. But just prior to this there was a setback, in the form of the discovery of a population of great crested newts. 'This threw a spanner in the works,' he says. 'At that time we were looking to be on site in the early part of 1997, but before that we had to clear the site of the newts.' Halcrow came up with a scheme for translocating the creatures. 'Normally the strategy is to try and trap them over three breeding seasons,' says Halcrow project engineer Michael Nutt. 'Clearly this was not possible, and would have jeopardised the ERDF grant.' Instead a strategy was agreed with English Nature which involved 15km of drift fencing, low polythene fencing which was dug in to prevent them burrowing underneath, and channelled them into traps which were checked on a daily basis. They were then taken to seclusion areas. Some 500 were found against a predicted 300.
Taylor Woodrow Civil Engineering won the reclamation contract and started on site in June last year, just as the newt collection was finishing. The contract is design and build, with Wardell Armstrong as its designer, and Halcrow remaining closely involved as the employer's agent.
The massive clay pit, a legacy of the brickworks, covers the whole of the landscape area plus some of one of the development areas, explains Wardell Armstrong design co-ordinator Jan Lewis. It has been backfilled with a mixture of domestic waste and colliery waste washings, up to 20m deep, bringing with it the inevitable problems of settlement and methane and carbon dioxide production. Other constraints were the levels of the development areas - the planners want them to be as low as possible to minimise visual impact. Drainage for the site was a problem. There was a simple ditch system, and frequent flooding of nearby roads, he adds. There was also domestic waste dumped outside the main area. And if that wasn't enough to contend with, there were coal workings on the site, and 14 shafts needed to be investigated.
Mining ceased in 1962, leaving two spoil heaps in the north of the site, says Lewis, and the brickworks closed 10 years later, with backfilling completed in 1992. 'It left 15ha of the site as a black, unvegetated landscape,' he says.
'There was only an 18 month construction period, and the way we viewed it was that the earthworks had to be finished by October,' says Taylor Woodrow Civil Engineering project manager David Fall. Managing the earthworks was critical to the programme. If it had extended into the next year for any reason it would have seriously affected our ability to complete the work.' Total muckshift was of the order of 300,000m3, with the work carried out by Greyhound Plant.
'In the development areas, once material had been scraped off to form the platforms, there was still made ground beneath,' says Lewis. In the first development area, it was dug down 3m to natural ground and recompacted back up. The other area, within the deep clay pit, will be used for car parking only. But there were some deep areas of made ground in the other parts. Here, the top 3m was recompacted, and surcharged.
'It was inevitable that the access roads had to go over some of this pit, and again the treatment was surcharging,' adds Lewis.
In the main pit, there is domestic waste down to 20m. The initial thought as part of the tender process was to create an impermeable barrier encapsulating the site though it couldn't go all the way around the pit, as this extends beyond the site. But leachate would have built up within the barrier and flows around would have been changed. Instead, a barrier was chosen which would vent gas. Low levels of leachate can be tolerated, as happens at present.
The scheme involves construction of large, 0.5m diameter boreholes, between 10m and 12m deep, every 3m. These are filled with gravel and a pipe with slots. They will be linked by a horizontal trench, with vents sticking up at intervals. Typically vents are at a low level, though these are interspersed with high level vents which have rotating cowls which spin and draw out the gas. In all there are some 430 boreholes, and 67 vents. Installation of the vertical gas venting boreholes, carried out by Taylor Woodrow in-house company Foundation Engineering, has been completed. 'It was a colossal production rate - 50 a day was the maximum, installed using two drilling rigs with a service crane,' says Fall. 'Site agent Wyn Owens is a very persuasive sort of chap.'
There are also the problems of abandoned shafts. Drilling and grouting is complicated because it is not known exactly where buildings will go 'although we have a fair idea of where they can't', says Bird.
Largest of the shafts is 4m diameter, and depths are to 300m. Backfilling varied considerably, says Lewis, adding that sometimes in the older shafts a staging was put in, of railway sleepers or steel, with a plug of material on top. 'We drill through the shaft collar to the base, and grout back up in 3m stages. Where the made ground is shallow we put a reinforced concrete cap on it as well,' he adds. Where the made ground is deep, complete excavation is not practical and a grout plug is drilled around the surface - consisting of small holes, filled up with grout, penetrating about 12m. The grouting work is carried out by Midland Drilling & Grouting.
Making the site structurally safe is only part of the task. The balancing ponds cater for a 1 in 100 year storm, and also take account of other developments. An existing small ditch was followed to some extent, and the only way to route the water down the 20m in level and out from the site was between the two development areas.
Landscaping is also important. 'It is good being involved in a scheme that is enhancing what was a derelict site as well as providing industrial units,' says Halcrow project engineer Martin Cooper.
Simply putting topsoil on the 'moonscape' would not have worked; nothing would have grown. Instead it has been contoured into a dome shape, so that water won't pond, explains Lewis, with the surface ripped up to allow the soil structure to be integrated. Trees, shrubs and grassland will be planted, and the project is part of the regional Forest of Mercia initiative.
The contractor has a five year maintenance period during which anything that dies will have to be replaced. There will also be planting in the water areas, to encourage flora and fauna, including all stages of the newts' cycle.
'We are still continuing to develop the design,' adds Fall. 'It's going to be a fantastic feature for the community.'