The information below is provided for river users who are engaged in passage planning or planning new developments / river services on the River Thames in the vicinity of the seven existing Thames Water CSO (Combined Sewer Overflow) locations that have had their positions altered (further into the river) by the Tideway Project.
These sites are Putney Embankment (PUTEF), Chelsea Embankment (CHEEF), Heathwall Pumping Station (HEAPS) Nine Elms, Albert Bridge (ALBEF), Victoria Embankment (VCTEF), Blackfriars Bridge (BLABF) and King Edward Memorial Park (KEMPF).
DRAs (Designer Risk Assessments) have been produced for each site that assesses the potential hazards to river users posed by CSO discharges at each site. River users should be aware that the information was prepared to support Tideway’s risk assessment of interim and permanent operation of the tunnel and may not be directly relevant to river user specific assessments. River users should note the following and refer to the DRAs (see below) and Notice to Mariners for further information:
- Revised location of the CSOs in the river – the seven altered CSOs have moved in relation to the historic CSO both up/down stream and further out towards the navigable channel
- Frequency and severity of discharges are set out in DRA Section 4 - Site Discharge Prior to the tunnel being commissioned the number of discharges from the existing seven CSO locations varies between 10 and 34 events per typical year (depending on site) and once the tunnel is fully commissioned this will reduce to ~4 events per typical year. A worst-case scenario discharge rate of a 1 in 15-year storm event at MLWS has been analysed to assess the impacts to vessels within zones of impact and vessel accessibility.
- Potential effects of the more severe discharges on passing vessels, including possibilities of drift, swamping and barges over‐running are assessed in DRA Section 5 - Impacts of discharge on the different classes of vessels and Section 6 - Ship simulation comparison.
- Extent that CSO discharges extend across the navigation channel and tidal considerations are assessed in DRA Section 4 - Site Discharge Activity.
- Tideway CSO discharge warning system - mitigations in the form of a CSO Discharge Warning System have been implemented to reduce impacts and river users are referred to the PLA Notices to Mariners P6-24 for further information. (note it is not possible to predict the severity of a CSO discharge occurring in real‐time)
River users are advised that Tideway are currently in the process of connecting the amended seven CSO’s on the Thames to the tunnel. During this commissioning process there will be a period where the CSO’s are not connected to, or are only partly connected to, the Tunnel. This could result in higher frequency discharges to river than in the permanent (tunnel fully commissioned) case. It is expected this period will be in effect until April 2025.
If river users have any questions regarding the DRA’s or CSO discharges from the seven revised locations and how they could affect river operations, they should contact Tideway via [email protected] and request to be put in contact with Tideway’s CSO Discharge Warning System ‘Person in Charge’.
Disclaimer
River users should be aware that the information was prepared to support Tideway’s risk assessment of the operation of the Tideway tunnel and may not be directly relevant to river user specific assessments. River users shall make its own enquiries to satisfy itself as to the accuracy, quality and completeness of any Tideway Documentation supplied to it by or on behalf of Tideway and shall not be entitled to rely on the Tideway Documentation and must use its own skill and judgement in relation to its use of the Tideway Documentation. River users use of the Tideway Documentation is entirely at its own risk.
Tideway gives no representations, warranties or conditions, whether express or implied, in respect of any Tideway Documentation supplied to it by or on behalf of Tideway and any such representations, warranties or conditions in respect of any Tideway Documentation and all liabilities arising from the supply or use of the Tideway Documentation and for any reliance on the results arising out of the use of the Tideway Documentation, are excluded to the fullest extent permitted by law.
