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The Project Control Framework
This framework sets out how we, together with the Department for Transport, manage and deliver major road improvement projects.
A417 Cowley to Brockworth Bypass Improvement
10 WASTE MANAGEMENT
10.1 All three options would generate excess material, which would be required to be removed off site for re-use, recycling or disposal. The following text discusses the potential amounts that may be generated. These figures are preliminary at this stage and would be modified as detailed design is undertaken.
Option 2 -On-Line with Grade Separated Junction at Air Balloon
10.2 Initial considerations of earthworks for this option indicate the following:
- Air Balloon Roundabout - although a detailed cut and fill assessment has not been undertaken to date, it is considered that this area of the scheme would be in excess by approximately 75,000m3 should Option 2 be adopted. The fill generated from the Option 2 cuttings is considered to be a good quality and would be suitable for re-use as an engineering fill elsewhere on the scheme;
- The widening of the Birdlip bypass would require the new road element to be constructed on a slight embankment. Between 80,000-100,000m3 of material would be required (depending on the adjacent landscaping proposed). A small volume of this would come from the excavations of the new slips at Birdlip. The remainder would be available from the Nettleton (Cowley) cutting and any environmental bunding / landscaping. The material from both sources is predicted to be of good quality;
- A cutting would carry the new carriageway from where Cowley Roundabout currently lies to the east of the current road alignment. A bill of quantities previously generated for the Nettleton Bypass indicates an approximate volume of 434,000 m3 of materials would be produced using conservative sideslope values. This could be significantly reduced by using different engineering techniques to steepen sideslopes. Some of this would be used to create an embankment and screening bunds across a small valley adjacent to the Golden Hart public House and near the current Cowley roundabout. It is estimated that between 60,000 and 90,000m3 may be required. In addition, some can be used to face some of the structures at the Air Balloon. Once the detailed design of the scheme is undertaken and a vertical alignment is produced it would be possible to identify this figure in more detail. However, for the purposes of this assessment it is assumed the cutting would generate up to 350,000m3 of excess material. Some of this would be required for earthworks along the new Birdlip bypass (the volume of which can only be estimated at present without a detailed engineering and landscape design). However, it is probable that a large proportion of the material would still require sale or disposal. The material is predicted to be high quality limestone's (it is the same material as was quarried at the adjacent quarry) and be of commercial value. It is also possible that some of the material could be made available for local community projects or quarry restoration if these are ongoing at the time of excavation; and
- The widening below the escarpment, where an additional two lanes are to be provided, would require a significant amount of fill material. It has been estimated that, depending on the height of embankment adopted, between 35,000m3and 100,000m3 would be required. Where widening within the existing embankment width is adopted no significant quantities of fill are considered necessary.
10.3 Overall, the scheme would generate a surplus of excavated geological materials that would be classified as waste if they are not used on the scheme. Much of this material would have a commercial value, but whether suitable uses are available at the same time as the material is unknown and the effect on other local businesses quarrying or selling stone would have to be assessed. Local Authorities have pointed to the Cotswold Water Park and their requirement for surplus material for quarry restoration. It is possible that restoration of one of these quarries using excavated materials would be exempt from Waste Licensing Regulations (see restrictions on exemptions in Table 10-1). The amount of fill allowed would depend upon the end-use. If the quarry site were to be restored to agriculture, then a layer up to 2m deep could be deposited under the exemption. if buildings or other end-uses were considered, the volumes exempt would be unlimited for inert waste. Discussions with the Cotswold Water Park Society have indicated that it is likely that local mineral operators could accept the waste so long as the material meets certain criteria, and that transport routes could be agreed with local authorities. The acceptance criteria on wastes to be deposited are imposed by the Environment Agency. They include that the material should be highly permeable (so that it does not affect groundwater flow or recharge, and that it should be clean. The majority of surplus material generated in Option 2 should meet these criteria.
10.4 At present it is not possible to confirm if such a route would be available for the re-use of waste materials produced on the scheme at the time it arises. If it were, then disposal costs would be significantly reduced and would then comprise mainly transportation costs (in the order of £15-£20 per cubic metre at 2002 prices). It is recommended to re-visit this possibility at a later date when the time that wastes would be generated is better understood and when planning for the Cotswold Water Park is more defined.
Option 1 - On-line with Signalised Junction at Air Balloon
10.5 The change in junction type at Air Balloon Roundabout would have very little difference in terms of the wastes produced over Option 2. The re-arrangement of the existing roundabout would mainly be at grade with only a small requirement for levelling to be undertaken.
10.6 As with Option 2, there would be a small requirement for material to widen the Birdlip bypass. This would be provided from the material cut from the new Birdlip access slips and from the Nettleton (Cowley) cutting.
10.7 As with Option 2 the proposed new Nettleton bypass would pass through cutting. The design of this element of the scheme is identical to Option 2. This element would generate a large surplus of high quality limestone's which would have to be disposed of or sold commercially. The discussion in option 1 on possible other re-use options also applies to this option.
Option 3 - Tunnel Option
10.8 The tunnel option would generate significant additional volumes of waste materials over Options 1 and 2. These would be generated from the excavation of the two tunnel bores, the 27 interconnections between the bores, and the creation of two portal faces. Initial calculations have indicated that approximately 950,000 m3of material would be excavated during the construction of the tunnels. The upper 34% of the tunnel length would be through hard limestone (329,500 m3). This material would be mined, and the majority can be re-used. For the purposes of this study it has been assumed that 90% can be re-used, either on the site or sold for off site use. Uses on-site 90 include as aggregate in construction, road base or mixed with concrete to enable the portal faces to "mature" or weather with age. In addition, this material can be used in landscaping and for dry stone walling to define field boundaries where this fits in with the local landscape. The remaining 10% would be treated as waste material. Further geotechnical investigation, however, may show that some of this material may have a commercial use. Such commercial uses could be:
- Manufacture of reconstituted stone;
- Road base materials;
- Creation of hardstanding sub-base;
- Intermediate cover at local landfills.
10.9 The lower 66% of the tunnel length passes through clays and a mixture of slip material (619,560 m3). The use of this material on the scheme would be limited due to the small areas available for landforming and landscaping and for the creation of the header reservoir to hold fire water. For the purposes of this study it has been assumed that 25% can be re-used, although this figure would have to be confirmed once a detailed engineering and landscape design and a detailed geotechnical survey has been completed. The remaining material would be classified as waste, even if alternative uses off-site are identified. Such re-use or recycling could be undertaken so long as appropriate schemes are occurring at the same time, as the material becomes available. Such re-use schemes would have to take into account the nature and physico-chemical properties of the materials, and some uses may only be possible following processing and re-use. Re-use options could include:
- Off-site landforming or environmental schemes (noise or landscape bunds);
- Quarry restoration;
- Capping contaminated land (if permeability is sufficiently low and material can be graded to create a material of sufficient homogeneity); and
- Landfill cover (final or intermediate).
10.10 The likelihood for such uses being available at the time of generation cannot be confirmed at present. It is highly likely that a proportion of this material can be re-used on other sites given that certain business sectors have a constant need for such material. The longer period over which materials are generated during tunnel construction (when compared with on-line options) would assist in this respect, as the local market for such materials would be less likely to be swamped with such material. It would be important to use local re-use schemes rather than transport the material over great distances. The Cotswold Water Park may be one such opportunity. Discussions with the Cotswold Water Park Society have indicated that it is likely that local mineral operators could accept the waste so long as the material meets certain criteria, and that transport routes could be agreed with local authorities. Acceptance criteria are placed on wastes to be deposited and these are imposed by the Environment Agency. As discussed previously, they include that the material should be highly permeable (so that it does not affect groundwater flow or recharge, and that it should be clean.
10.11 In addition to the material generated by the excavation of the tunnel, Option 3 also includes the first half of the Nettleton (Cowley) cutting as discussed in Options 1 and 2. This potentially could generate over 150,000m3of material. However, the potential for re-use on the scheme is smaller than in either option 1 or 2 as the requirement for the widening of the Birdlip bypass is removed. The majority of this material would, therefore have to be sold or disposed of.
10.12 As for Options 1 and 2 the potential for material to be used in local remediation activities exists. Local Authorities have pointed to the Cotswold Water Park and the requirement for surplus material for quarry restoration. It is possible that restoration of one of these quarries using excavated materials would be exempt from Waste Licensing. The amount of fill requiring disposal would be considerably larger than in Options 1 and 2, and the amount allowed to be re-used would depend upon the end-use. Discussions have indicated that this may be a potential route for disposal of the permeable material generated (the limestones). However, the clays in the lower 66% of the tunnel are unlikely to meet the Environment Agency acceptance criteria, and therefore would still have to be removed for disposal elsewhere. At present it is not possible to confirm if the Water Park is a route available for the re-use of some of the waste materials produced on the scheme, especially given the greater quantities generated over Options 1 and 2. If it were, then disposal costs would be significantly reduced. It is recommended to re-visit this possibility at a later date when the time when wastes would be generated is better understood.
10.13 Without re-use, disposal costs could be in the order of £30-50 per cubic metre (2002 prices) assuming local disposal locations are available. With re-use, the disposal costs would only involve the transport element of the cost. This could be in the range of £15-20 per cubic metre (2002 prices) depending on the bulking factor achieved and the distance travelled. These costs would have to be revised once the timing of arisings is better defined, more information on the waste materials is gathered, and the availability of disposal options known.
10.14 Transport of the waste material off-site also potentially causes problems. Initial estimates, based on a construction period of one year, suggest that up to 1,000 truck loads per week would be required to transport surplus material off-site. Taking into account vehicle movements to the site, this would result in up to 2,000 HGV movements per week, all of which would have to use the existing A417. The potential for increased congestion is thus not insignificant. Taken over a longer period, say 3 years, this would still generate in the order of 650-700 HGV movements per week.
10.15 Depending on the availability of disposal sites to take the material, it is likely that there would be a need for storage compounds on-site which could be substantial in size. These would generate their own environmental impacts including landscape and visual, as well as the potential for surface water run-off to nearby streams and to groundwater. These impacts would need to be assessed once the likely phasing of construction are known.
