EIA and route selection for pipelines

17th September 2012

Related Topics

Related tags

  • Stakeholder engagement ,
  • Construction ,
  • Water ,
  • Engagement



Chris Rochfort, from MWH, discusses how the possibility of environmental impact assessment (EIA) can directly influence the route for a new pipeline at the early project stages

Under the Town and Country Planning (EIA) Regulations 2011, water and sewerage pipeline projects are sometimes the subject of EIA. Guidance states that such pipelines are Schedule 2 developments and must be screened for EIA, with projects over 5km in length and those affecting designated sites more likely to trigger EIA.

Once such example is a new 18km water main in the Thames Valley area, being constructed by Optimise on behalf of Thames Water, which was subject to an investigation under the Habitats Directive.

The Environment Agency had determined that water abstraction at a water treatment works should be reduced to protect a nearby wetland and river habitat designated as a special area of conservation (SAC).

Increased abstraction was agreed 18km downstream where the SAC site would not be affected, and a new 18km pipeline was required to transfer this supply to the local area.

Taking into account the potential need for an EIA, a route corridor appraisal was undertaken that evaluated a number of alternatives in a large study area and subsequently identified a preferred route for which an EIA screening opinion was requested.

The preferred route minimised socioeconomic impact on the local population, by skirting major towns and villages, and by minimising traffic disruption by avoiding roads where possible.

The route minimised environmental impact by avoiding areas of ecological and archaeological importance, where practicable, or by using sensitive construction methods, for example, trenchless river crossings.

A 1km section of the route was constrained and two options were available to Optimise:

  • Option 1: the most direct route is a quiet road that does not pass any residential properties, but does pass through an Iron Age hill fort, part of which is a scheduled monument.
  • Option 2: is a busy local road that was not a direct route and would have required an additional 500m of pipe to be laid at considerable additional cost and traffic impact. In addition it passed by numerous residential properties that would be impacted by access issues, as well as dust and noise nuisance.

A decision was made to select Option 1 - the most direct route. It was highlighted that: the scheduled area would be avoided; surveys could reveal important information about the hill fort; and that impact could be minimised by tunnelling the water main underneath the area of archaeological interest.

As statutory undertakers, water companies benefit from significant permitted development rights – all underground works are deemed as permitted development under the Town and Country Planning (General Permitted Development) Order 1995. However, critically, permitted development rights do not apply if the development is screened as an EIA development, instead, a planning application is required.

Screening for EIA

A detailed environmental report was included with the EIA screening request which provided the information necessary for the local planning authority to give its EIA screening opinion, and highlighted the environmentally-led design.

Furthermore, Optimise described its standard approach to environmental management; which would deliver mitigation to the same standard as any planning conditions that might otherwise be imposed.

Optimise also has a proven track record in proactive stakeholder engagement, regardless of the need for EIA. As a matter of course, Optimise engages with local communities affected by a scheme, to ensure that potential socioeconomic impacts are considered and to keep them informed of the proposed works. Prior to start on site, drop-in sessions are organised at local venues to encourage local residents to meet the design and construction teams.

In its first EIA screening opinion, the local planning authority concluded the potential impacts on the scheduled monument were significant and that an EIA was required.

A meeting was held at the authority’s offices where the scheme was discussed. The constraints and opportunities of working in or avoiding the scheduled monument were discussed and it was agreed, in principle, that if the monument could be avoided the scheme was likely to be deemed “not an EIA development”.

As a result, Optimise made the decision that, despite the additional 500m and associated costs, the Option 2 route would be preferable in terms of potential delays etc. Consequently a revised EIA screening request was sent to the authority, which confirmed that no EIA was required for the revised route.


By selecting Option 2 over Option 1, potential long-term impacts on the scheduled monument were avoided, which was deemed more significant than the short-term traffic and nuisance impacts.

EIA was avoided as the local planning authority recognised that the issues associated with Option 2 could not be deemed likely to lead to significant environmental effects.

The open discussions navigated the project through the complexities of the EIA regime to the mutual benefit of Optimise and the planning authority. Potential delays, procedural burden and paperwork on both sides was avoided and the project proceeded under permitted development rights. Nonetheless, Optimise’s standard approach in terms of environmental management and stakeholder engagement will ensure that the project is built to best practice.

This article was written as a contribution to the EIA Quality Mark’s commitment to improving EIA practice.

Chris Rochfort ([email protected]) is a senior environmental advisor at MWH UK which is part of Optimise.

Optimise is a joint venture that has been awarded a large contract of work in Thames Water’s 2010–2015 investment programme.


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