From contamination to consensus

The solution? That depends on your perspective. The local authority’s priority is to rid itself of a blot on an otherwise thriving and prosperous townscape by cleaning it up, adding the kind of facilities that would regenerate the community, and meeting demand for affordable urban housing. The average housebuilder would take one look at the site’s risk/reward profile and pack it with high-density and relatively high-rise apartments to make it pay. The existing community wants the site left empty, fearful of both present contamination and future residents.

It has taken three years to mould these different objectives into a single coherent solution, overcome the countless regulatory hurdles, and raise the £3.3m in grant aid from SRB required to realise the vision. This month work starts on capping and remedying the site. Some 18 weeks later, Gleeson Homes will start building 88 one and two-bed apartments for its own market sale in three and four-storey timber-frame blocks and 46 three and four-bed three-storey houses for rent for Ealing Family Housing Association. There will be broader community benefits: a bridge across the River Kennet, linking new and existing residential, a riverside walk, and a creche and training centre to increase local employment opportunity.

Marginal now, mainstream soon

Bringing the site to this point has been costly. The costs and the risks in taking the scheme from concept to reality were borne by the site’s owner Gleeson, in much the same way as it would if it had an option on a greenfield site. Its consultants invested their time in the venture, until last year when grant was won to pay fees. Everyone involved could choose whether or not to take on the risk. “If anybody wanted to walk away they could,” says Clive Wilding, managing director of Gleeson Homes. It may not be so easy to pick and choose in future. Government proposals to make local authorities test sequentially any land release for housing may make the higher-risk urban site a national obligation.

Even without a sequential approach, Gleeson had its own imperative to develop Reading’s Kenavon Drive: it already owned a third of the site. It negotiated the purchase of the other two-thirds from the receiver, haggling down the price from a 1988 value, and spent seven months proving that the site could not viably be developed, unless it had grant aid. “We wouldn’t have gone out to find this site,” says Wilding. “Our options were to either turn it into a car park, or to make things happen. The site was not viable unless we had subsidy. The remedial costs were so high that even very dense development didn’t square the circle. Also we believe that the market is moving away from high density, smaller units. We wanted larger apartments.”

With 87% of town centre land developed Reading Borough Council was sympathetic to Gleeson’s concerns, but mindful of its own. “Because of the lack of land we have to look at these kind of sites. We are an urban authority with acute housing needs. Our shortfall in affordable housing units against targets will be 10 000 by 2004,” says Nigel Bailey, housing, planning and development manager with Reading Borough Council. “We had to debate whether we would have private development, just to get the site cleaned up. But here we were adamant that we wanted other benefits to come through to the community - and if we agreed to private housing in this case, other developers would want to do the same elsewhere. This is not just about decontamination, it’s about quality of life.”

Providing that quality of life has resulted in a low density, of about 12 homes per acre - although social units are sizable family houses with up to 120 m2 of space. “It’s a low density for Reading, but we want to see a mix of housing here. Ealing Family Housing Association want larger houses for ethnic community tenants,” says Bailey. Site layout gives the maximum river views, although architect Bundey & Rodgers had other constraints. “Two high pressure gas mains running through the site were a strong determinant. We had to have the access road there,” says Michael Hales, project architect.

Ealing Family HA’s track record of innovative partnership development in Reading made it the first choice social partner for the scheme, especially when it came to overcoming community resistance - which could have been heightened by an SRB grant award of only half the hoped for sum to cover all the community improvements wanted. “That has focused attention on the community. We don’t have the option of saying that the contamination costs are high, so we won’t give you a bridge,” says Julia Moulder, development director of Ealing Family.

Remedying site contamination accounts for more than 25% of the scheme’s predicted costs. Hotspots of heavily polluted ground will be removed, the site levelled, existing concrete structures crushed down to form a 300 mm break layer, and a 700-800 mm-layer of compacted engineered clay laid to complete the capping. The gasworks’ old concrete tanks buried deeper underground are expected to remain and will only pose a problem for the piling rigs. “We’ve assessed the risk,” says Wilding. The developer also brought in its insurer early, which as Martin Horsler, manager of Zurich Building Guarantees says, “gives the insurer a better handle on how well the risk is being managed.” Which in turn can cut premiums.

A 900 mm-thick compacted engineered clay bund will stop contaminants migrating from an adjoining gasworks site. Over the longer term a bioremediation process, which involves putting contaminant-eating bugs into the ground, will deal with mobile contaminants. To prevent rainwater leaching into the ground and protect residents, homes will be surrounded by a hard landscape of terraces and planter boxes. “We have to look at how to have a high-quality landscape without breaching the cap. It is a matter of getting residents to understand that they won’t have flower beds and grass,” says Moulder. Ealing Family’s duty to manage the contamination will be ongoing as bioremediation pumps have to be maintained and contractors digging up the ground alerted to potential hazards.

For the housing association such duties are new, as is the use of timber-frame. Here timber-frame was chosen because its light weight, allied with ground beams, allows the scheme to comply with an Environment Agency stipulation that no piling should take place within 2 m of the aquifer. ISDN lines, to encourage home working, and grey water recycling are among other innovations in the scheme. “Innovation was driven by the need to decontaminate, because costs are high, even with the SRB,” says Moulder. “This scheme is no worse value than any of our other schemes.”

Now the scheme is being put through a value engineering process to ensure efficiency in design. The BRE’s Calibre system will probably be used to produce efficiency of build. Gleeson is looking to partner with key subcontractors, and to make subbies’ commitment to training a key element of the partnering agreement. It could be one of the first demonstration projects tracked by the Government’s Housing Forum. Yet these and other achievements at Kenavon are being made largely in spite of rather than thanks to Government policy, and there are fears that there is little assistance on the horizon.