Support act takes the lead

The standard definition of infrastructure is public roads and other services, such as water, electricity, telecommunications, gas and sewers. But thanks partly to recent government policies, it has also come to include all the matters that need to be dealt with prior to commercial elements of a scheme being released, including sustainability and the environment. Infrastructure issues may range from remediating contaminated land to limiting noise pollution from construction works. Here are eight typical infrastructure elements.

1 Creating the development platform

Creating the development platform may simply involve preparing an existing site prior to development. On a greenfield site works may be minimal, but on a brownfield or regeneration site there may be major civil works where remodelling, remediation or relocation of existing uses is necessary.

Examples of such works are:

• Remediation of contamination arising from gas works and coal mining
• Relocation of grade car parking into decked structures to release prime development land
• Remodelling of quarry overburden material – to provide a compacted development platform and maximise site value
• Topsoil strip and stockpiling from existing farm land
• Demolition and clearance of existing industrial buildings
• Drainage of marshland and ground improvement

Where site contours are unsuitable for development, earth moving and other works will be necessary to create a suitable platform. The importing or exporting of earth may be restricted or prohibited because of its impact on the existing local environment. As a result, reprofiling within sites is becoming increasingly common, both to comply with local authority policies and minimise costs. Maximum use of “natural features” within landscape schemes can improve the viability of such projects.

• Traditionally surface water drainage has used underground piped systems to convey water away and prevent localised flooding. This increases the speed of run-off but can change the flooding regime of the catchment. As a result, the Environment Agency is requesting that sustainable drainage systems are used to control surface water run-off as close to its point of origin as possible, before it enters a watercourse. This has signalled a move away from piped drainage systems to engineering solutions that mimic natural drainage processes.
• Sustainable drainage options include:
• preventive measures – for example, rainwater recycling, good-practice design and maintenance
• filter strips and swales (vegetated landscape features with smooth surfaces and a gentle downhill gradient to drain water evenly off impermeable surfaces, mimicking natural drainage patterns)
• filter drains and permeable and porous pavements to allow rainwater and run-off to infiltrate into permeable material placed below ground to store water prior to discharge
• infiltration devices – below-ground or surface structures to drain water directly into the ground (soakaways, infiltration trenches, basins and swales with infiltration)
• basins and pond structures designed to hold water when it rains.

Specialist consultants are engaged on major schemes to give transportation and engineering advice. Their work may include transportation modelling exercises and the design of major highway and public transport systems to support the development.

Basic cost considerations include:

• Roads have to comply with strict design parameters and are constructed from a limited range of materials. The difference in cost per metre comes from their capacity and number of lanes.
• Adjacent pavements can be subject to broad cost variation.

The market for primary utilities infrastructure has undergone significant change over the last five years. The Competition Act 1998, the Utilities Act 2000 and the Water Industry Act 2003 have deregulated the market and provided opportunities to procure utilities infrastructure from alternative sources to the host statutory bodies. This new arrangement is often referred to as “contestable works”. The chart on the next page defines the key contestable works. Alterations/diversions of existing networks are still via the host statutory bodies and are known as “non-contestable works”.

In this deregulated marketplace a developer has a choice over who designs, constructs, owns and supplies utility services. This gives the client access to an optimum cost-effective solution and a much higher degree of control over the delivery of services.

Spine roads of major developments often determine the route of incoming statutory authority supplies. Services need to be accessible and under a surface that can be easily taken up, relaid and re-instated. Pre-planning is required, including the provision of additional “future proofing” ducts to allow potential re-routing and expansion at minimal cost and disruption.

On brownfield sites there may be existing utilities within the development boundary. If so, it may be necessary to survey, locate and divert existing utilities to give a clear site. Where diversion is not possible or acceptable, provisions must be made to protect the existing installation while work proceeds.

Traditionally, utility providers work independently on a development, but now multi-utility co-ordination is becoming increasingly popular, often by outsourcing to specific multi-utility consultants or to a contractor prepared to take responsibility for the statutory undertaker. The responsible party obtains network plans, commissions detailed design drawings showing the route of new pipes and cabling, and installs and disposes of assets. Service connections need to be coordinated, involving logistical management, meter installation and the adoption of new infrastructure. While the thinking and preparation behind this exercise may take longer, the utility providers will be co-ordinated in such a way that installation costs and time on site can be kept to a minimum.

5 Public open space landscaping

Local planning authorities have clear policies for protection and creation of public open space and playing fields, and new developments should generally incorporate sufficient provision where such spaces do not exist.

Landscaping both reduces the visual impact of a new development and pro-actively greens the environment. The government attaches particular importance to the latter in enhancing the quality of the land, assisting permeability of land for storm drainage and contributing to biodiversity. For example, if an area of grass is structured in such a way as to have a gentle slope in the right direction, it will not only be aesthetically pleasing but can also form a swale that helps to manage the flow of water to an appropriate water course.

Landscaping both reduces the visual impact of a new development and pro-actively greens the environment

6 Maintaining key elements of existing environmental conditions

Ecology

If a proposed site for development is greenfield, it is likely that there will be existing ecological conditions that need to be maintained. On brownfield sites, the history of the land and its previous use will determine the amount of plants and wildlife that need to be conserved. If the land was contaminated, leading to a lack of green space and wildlife, steps will have to be taken to green the development.

It is important that surveys of wildlife in the area are undertaken. Where habitats of protected species do not fit in with development plans, suitable receptor sites will have to be set up so that these habitats can be moved to a more acceptable location. Ecological and biodiversity issues on major sites are often policed by an Ecological Clerk of Works.

Noise

Noise surveys can be carried out to establish baseline noise levels across a site, and these are put into noise exposure categories. These results are used in the masterplanning process to show appropriate and inappropriate areas for noise-sensitive uses such as residential.

It will be hard to reconcile some land uses, such as housing, hospitals or schools, with activities that generate high levels of noise, but attempts should be made to ensure that, wherever practicable, noise-sensitive developments are separated from major sources of noise. Development involving noisy activities should, if possible, be sited away from existing or proposed noise-sensitive land uses. Where this is not possible, local planning authorities may consider whether it is practicable to control or reduce noise levels, or to mitigate the impact of noise through the use of planning conditions.

Air quality

The impacts of construction and operation of a development on local air quality must be assessed, including potential pollution effects from increased traffic flows or industrial activity. The predicted concentrations must be assessed against air quality objectives. If there is a risk that levels of particular pollutants will be higher than these objectives, the local authority must designate an air quality management area, draw up an action plan and set out the measures it will to take in pursuit of the objectives. It is often necessary to monitor air quality in and around a development both during construction and in early stages of occupation/operation.

7 Planning obligations

It may be possible to increase the acceptability of development proposals through the use of planning conditions or obligations (Section106 agreements), negotiated between local planning authorities and developers. One of the most common obligations is a requirement to hand a proportion of homes on a development over to a housing association for low-cost rent.

Consideration also needs to be given to community facilities, such as libraries and health centres, and whether these have the capacity and resources to deal with the increases in population. New facilities may need to be included in the masterplan or sums paid by the developer to the local authority.

8 Phasing and temporary works

In an ideal world all the infrastructure on a site would be undertaken at once, and after that the development would be built. In reality financial constraints generally make this impossible and most large schemes will need a phasing strategy to identify steps to completion. All the interim stages needed to move a scheme from pre-development state to full build out must be taken into account. Inevitably there will be phasing costs which often consist of sacrificial or temporary works, such as diversions of services, which support an early phase but are not required in the final solution. These issues are often not apparent from the overall scheme masterplan.

Conclusion

Cashflow is of paramount importance to most developers. Their financial appraisal will look healthier if they are able to spend just enough on infrastructure in order to release income generating elements of their development. However, they must balance such financial control against potential opportunities to spend more in one area (eg. roads) to avoid expenditure on temporary facilities in another (eg. schools). Furthermore, the income side of the developer’s appraisal may be boosted if more infrastructure and an enhanced public realm are available sooner, as house prices will be higher in an area that has a “finished” public realm, rather than one that looks to be part of a building site.