Question to the Department for Transport:

To ask His Majesty's Government how they intend to ensure that the new discharge pipes connected to the HS2 project, leading to Yeading Brook behind Ruislip Gardens Station, have a discharge licence; whether they can describe what chemicals and volumes are permitted under this licence; who is doing the water quality monitoring; and where the monitoring data appears locally.

Any discharges of water from the HS2 project to the natural environment require discharge consents, approved by the regulator – the Environment Agency (‘EA’), as specified in Schedule 33 Part 5 of the High Speed Rail (London – West Midlands) Act 2017.

There is an agreed consent to discharge water from the South Ruislip Vent Shaft site to a drain that discharges to the Yeading Brook. The conditions for this state the maximum limits of the following parameters:

• Total daily discharge volume - 3024m³/day
• Rate of discharge - 35 litres per second
• Suspended solids - 50 mg/l
• pH - 6 to 9
• Sulphate - 2000 mg/l
• Visible oil or grease as is reasonably practicable - No significant trace present, so far

The consent states that the sulphate levels within the water are to be recorded and reported to the EA on a monthly basis. The total daily discharge volume and the rate of discharge are to be recorded and reported as and when requested by the EA.