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Chartered Institution of Water and
Environmental Management (CIWEM)

106-109 Saffron Hill, London, EC1N 8QS  
Tel: 020 7831 3110 Fax: 020 7405 4967
 

A46 NEWARK TO WIDMERPOOL IMPROVEMENTS

Client: Highways Agency

Principal Contractor: Balfour Beatty Civil Engineering Ltd.

Designer: URS Infrastructure & Environment UK Ltd.

URS were appointed as Contractor's Designer by Balfour Beatty on their £265M Early Contractor Involvement contract to improve the A46 between Widmerpool and Newark. The project spanned a 28 km stretch of the A46 between the A606 two level junction at Widmerpool to an improved roundabout at Farndon, just south of Newark in Nottinghamshire. The aim of the scheme was to widen the existing A46, from a single carriageway to a dual carriageway to reduce congestion, improve safety and provide a bypass for East Stoke and Farndon including new junctions at Roehoe, Owthorpe, Stragglethorpe, Saxondale, Margidunum, Red Lodge, Flintham and Lodge Lane. As part of their Sustainability Vision, Balfour Beatty introduced "zero waste to landfill" targets and therefore expressed a desire to reuse all material generated from the improvement works.

With this "zero waste to landfill" goal in mind URS was commissioned by Balfour Beatty to prepare a Materials Management Plan ("MMP") in accordance with the 'Definition of Waste: Development Industry Code of Practice' ("CL:AIRE CoP") (CL:AIRE, 2008) which would include the reuse of the former A46 pavement materials.

URS produced the MMP which detailed the procedures and measures that should be taken to classify, track, store, and re-use all materials excavated including the former road planings. In particular the report detailed the procedures to deal with any of the former road planings that may be affected by elevated polycyclic aromatic hydrocarbons (PAHs) derived from coal tar products. Any material with elevated PAH which could not be used in unbound applications was suggested to be reused within the road sub-base as part of the hydraulic bound mixture (HBM).

URS produced a series of designs which allowed the PAH affected planings to be blended with imported clean granular material and cement to form the HBM pavement foundation. Three alternative HBM mixes based on the level of PAH contamination were presented; 50/50, 40/60 and 30/70 ratios of planings and scalpings. The scheme and mixes were based on detailed pre-works laboratory testing and analysis undertaken by both Balfour Beatty and URS within their own laboratories. The results of these findings were presented within a secondary Laboratory Testing Report and the conclusions used to support the scheme suggested in the MMP.

As part of these pre-works tests by URS, Ultraviolet Fluorescence (UVF) spectrometry was selected to trial as an analytical technique for onsite verification based on previous experience of successfully applying this technique on PAH affected soils. The UVF method was shown to reliably determine total PAH concentrations within the laboratory report and later in samples of planings from the site.

During the works samples were taken onsite for UVF testing at an approximate rate of 1 sample per 25m3. The use of UVF testing allowed the majority of the testing to be undertaken within an onsite laboratory, with only a number being tested by accredited laboratory for verification. This quick on-site test allowed Balfour Beatty to classify the planings and ensure they were directed to the right location for re-use in the pavement foundation.

To confirm that the reuse of the pavement planings within the HBM was acceptable, HBM cube samples were taken at 500m intervals where pavement planings were reused within the HBM material. These cube samples were subject to 4 day tank tests to determine leaching characteristics. Once the tank tests were completed the cubes were crushed and tested for PAH concentrations. The testing confirmed that the material re-used in the HBM mix met the environmental specifications outlined in the URS Laboratory Report and MMP.

URS produced a verification report for the works proving that the overall testing carried out for the reuse of materials within HBM mixes onsite met the environmental and geotechnical requirements for HBM within the A46 project. The report confirmed that the properties determined within the URS Laboratory Report were replicated onsite and that the materials operated as identified within the pre-works laboratory testing.

 

 

Project Example compiled by:

Robert Eaton

Campbell Ogilvie

Danny Hope

URS Infrastructure & Environment UK Ltd

 

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Chartered Institution of Water and
Environmental Management (CIWEM)

106-109 Saffron Hill, London, EC1N 8QS  
Tel: 020 7831 3110 Fax: 020 7405 4967

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