Contractor: Norwest Holst Ltd
The £8 million project forms part of the Trent Valley Four Tracking (TV4T) scheme, which encompasses a 12-mile stretch of the West Coast Mainline between Tamworth and Handsacre. Norwest Holst was awarded the Hademore Level Crossing contract in early 2006, which involved the construction of a new bridge to replace the level crossing, 1km of rail widening and five other reinforced concrete structures. Overbridge 90AA (OB90AA) replaces the level crossing and comprises a single-span portal structure with 600m of approach road on 8-m-high embankments. Approximately 80,000m3 of material was required for the embankment construction. The works interfaced with residential and commercial properties as well as agricultural land, the Birmingham and Fazeley Canal and a brook.
Aerial view of OB90AA and the associated embankments
To construct the approach road to OB90AA, it was necessary to dismantle and relocate a pair of Grade II Listed gate piers, which flanked the drive to Fisherwick Hall (now demolished). These gate piers were not only of cultural heritage value, they also offered nesting habitat for the Tree Sparrow (Passer montanus).
The planning consent required the piers to be dismantled stone by stone, numbered and dressed, and then moved to a secure storage area prior to re-erection. However, before commencing the dismantling process it was necessary to carefully remove the vegetation covering the piers and wrap them in debris netting. This measure was adopted in order to prevent tree sparrows from nesting in the piers, as they had been known to do in the past, thus ensuring there were no delays to the proposed works later in the year.
However, the netting of the gate piers meant that potential nesting habitat had been removed, which could have adversely affected the Tree Sparrow population in the area. It was therefore decided to erect nesting boxes in close proximity to the gate piers, offering alternative nesting opportunities for these birds.
In accordance with the Planning Consent and the Specification for an Archaeological Building Recording as issued by Staffordshire County Council, the dismantling process was fully documented and photographically recorded by The Linford Group Ltd (specialist stone masons) in partnership with Norwest Holst.
The gate piers now form a focal point on Fisherwick village green, much to the satisfaction of the Parish Council and the local residents. The efforts of the project team ensured that a 100% score was achieved for this section within the CEEQUAL assessment.
Gate piers re-erected on Fisherwick village green
Sustainability and Material Reuse
Since the works associated with the TV4T scheme were being carried out by a number of different contractors simultaneously, the demand for fill material import was high. Even though a number of quarries exist in the region for the import of material, Norwest Holst decided that an embankment design had to be produced that mitigated the risk of supplier shortages. It was essential to give the client maximum assurance that the critical date of Christmas 2006 for the opening of the bridge would be achieved. The consequences of not achieving the date would have led to a significant delay to the TV4T scheme.
On this basis it was decided that Pulverised Fuel Ash (PFA) would be a suitable alternative to quarried material and could be provided exclusively by Rugeley Power Station. Furthermore, detailed research showed that a heavy-duty geotextile could be used, instead of oversize stone, to prevent capillary action at the base of the embankment.
The substitution of quarried material for PFA and the use of a geotextile prevented exploitation of natural resources and thus minimised the environmental impact of the project on the local area. Using PFA as general fill puts the material back into the supply chain and effectively constitutes the reuse of a waste product.
The lighter bulk density of PFA in comparison to stone helped to remove haulage vehicles from the public highway and resulted in a subsequent reduction in carbon emissions during the delivery and placement process.
Class 2 clay used to retain the PFA during fill operations was sourced from other projects on TV4T that had a surplus of material. This would otherwise have been taken to a waste disposal facility, therefore Norwest Holst ensured a ‘Win-Win’ scenario with the client – import and disposal costs were reduced by diverting material from landfill.
The use of PFA as well as suitable ‘cut’ material from within the TV4T scheme envelope ensured that 57% of the materials used as bulk-fill were reclaimed and therefore reused. This, amongst other initiatives, ensured a percentage score of nearly 90% in the Material Use section of the CEEQUAL assessment.
Throughout the project, local stakeholders were informed of construction activities via regular newsletters and were also invited to attend open evenings in which they could raise concerns over the programme of works. The project was also registered under the Considerate Constructors scheme and gained positive feedback during the audit process.
In partnership with Network Rail and the British Trust for Conservation Volunteers (BTCV), Norwest Holst donated materials, labour and expertise for the improvement of a wildlife garden at Moorgate Primary School, Tamworth. The aim of the project was to make the garden more accessible for the school children so that they could spend more time studying amphibian and reptile species as well as invertebrates.
The flexible approach of the site team ensured that high percentage scores were achieved in both the Nuisance to Neighbours and Community Relations sections of the assessment.
The CEEQUAL assessment process enabled the site team to constantly monitor environmental performance of the project and identify weak areas where improvements could be made. Norwest Holst is proud to have been the only contractor that registered a project for CEEQUAL assessment within the TV4T scheme and the ‘Very Good’ rating is testament to the fact that contractors can make a difference regardless of client or designer involvement.