Balancing environmental compliance and wind turbine foundation excavation needs

Naturally Compliant was engaged to oversee the environmental compliance for one of the largest onshore windfarm projects at the time. As the Environmental Clerk of Works, our role involved a mix of responsibilities to report on the projects compliance and advise the Principal Contractor on how to achieve it.

We stepped in just as regulatory scrutiny from the Scottish Environmental Protection Agency (SEPA) was intensifying, primarily due to water pollution concerns.

Key challenges:

1. n ambiguous role: Balancing responsibilities for reporting and advisory functions.

2. Working with existing documentation: Upon review, there was limited guidance on water management.

3. Complex conditions: The geology of glacial till and bands of clays in addition to the climate in southwest Scotland produced significant volumes of "dirty water." Treating water with suspected clay particles is notoriously challenging.

4. Regulatory confusion: This project was regulated by the Water Environment (Controlled Activities) Regulations and SEPA’s general binding rules around visual discolouration – which can be subjective and as such invite conflict.

Related read: The potential impact of visible water discolouration from building sites.

Solution: Customised Water Management Plans

We initiated clear communication and advisory paths with the Principal Contractor and developed drainage designs for each new turbine base, employing Naturally Compliant’s ‘six steps for successful surface water management’.

Key actions:

1. Receptor mapping: Identified and mapped all water receptors and pathways from the turbine base.

2. Drainage optimisation: Installed upslope cutoff trenches to break hydrological connectivity where water was moving along the peat-clay interface.

3. Pump sizing: Coordinated with the contractors, we determined the size of pumps for draining the excavation, which then informed pond sizing.

4. Precipitation management: A separate pond was created for precipitation runoff, using guidelines from CIRIA.

This plan was issued to the section engineer for installation as part of the turbine foundation base activities.

Outcome: Proactive water management and reduced environmental impact

The project successfully demonstrated active management of "dirty" site water, justifying the use of chemical treatments alongside traditional gravity systems.

Recommendations:

Joining the project after all the project documents and behaviours had been established presented a significant challenge to promote positive change. As such the following recommendations were made:

1. Early consultation: Engage a consultant during the tendering phase for a more accurate budget and timeline.

2. Chemical treatments: Reserve these as a last resort, after modelling traditional gravity treatment systems.

3. Clarify regulatory requirements: Reduce conflict by seeking clarity on ambiguous guidelines like "visual discoloration."

4. Impact Assessment: Incorporate modelling at this stage for comprehensive mitigation strategies.

5. Budget appropriately: Recognise that water treatment comes with costs, either spatial or financial.

By implementing a meticulous and adaptive water management strategy, Naturally Compliant aided the project in navigating complex regulatory and environmental challenges.

For more information about how we can support the success of your next project, please don't hesitate to get in touch.