Case study – Environmental impacts – Pollution

Creating a safe diversion

The project team carrying out drainage discharge upgrades at our Cockfosters depot has been awarded Beacon site status for high standards of health, safety and environmental performance. Construction works began in 2007 after Cockfosters was identified as the highest priority site needing drainage upgrade.

Following completion of these works in March 2008, the team will carry out similar works at our Lillie Bridge, Northfields and Edgware depots.

The Cockfosters project has created the infrastructure to intercept water from a pit road that is used to clean train undercarriages. Three new holding tanks, sunk into the ground to minimise visual impact, hold the diverted waste until it is removed from the site and disposed of as hazardous waste.

This type of work is outside Tube Lines’ core project activities, but is the first of many that will capture and store contaminated water discharges from train maintenance so that they can be safely taken off-site for treatment.

Close liaison between the drainage team and the maintenance team running the depot was an essential success factor. “Because the depot operates 24 hours a day we had to make sure that we did not upset the balance of the depot’s work, which is essential to getting trains out and serving customers,” explains Sascha Paschen, Field Engineer.

Peter Riley, duty manager at Cockfosters depot, is convinced that careful planning paid off. “We planned every detail carefully to ensure minimum disruption to the depot,” he explains. “The drainage team had a project manager on-site to handle all contractor issues, which helped enormously. The main issue was co-ordinating deliveries to site and we set up a new turning circle at the top of the drive for the vehicles arriving on site to ease access. This has proved so useful we will be keeping it after the project has finished, giving the depot another lasting benefit from these works.

“Most of the time we were hardly aware that the site team was there – and it will be fantastic to be able to wash the pits clean without worrying about contaminating the surrounding area, helping us to look after the depot and environment more effectively.”

Footnote:
Further investigations are underway at another discharge point at the depot after we received two warning letters from the Environment Agency. We continue to liaise with the Environment Agency on this matter and will be submitting a technical pack detailing all sampling results from 2003.