Tidal Thames Quality Improvements Mogden Sewage Treatment Works May 2007
Objectives of the Presentation Proposed Improvements at Mogden. � Background to the quality of the River Thames � Objectives of the Proposed Improvements � The scope of the Proposed Improvements � Planning and environmental considerations � Consulting and informing
The Tidal River Thames River Roding River Beam River Ingrebourne River Lea River Beckton Riverside Southend Brent Thames Estuary Mogden Barrier Crossness Gravesend Long Reach
The quality of the River Thames � London’s sewers carry both sewage and rainwater. � Sewage treatment works have a limited capacity. During above average rainfall, the storm tanks fill up and storm sewage is designed to overflow into the River Thames. � Impacts on river water quality, wildlife and people who use the river.
Improvements to the tidal sewage treatment works � The Environment Agency has set revised treatment requirements for our Tideway sewage treatment works � Our regulator, Ofwat, has approved funding for a £400 million investment programme to improve London’s principal Sewage Treatment Works (STW): – Beckton, Crossness and Mogden – As well as the smaller Long Reach and Riverside STWs � Planned completion: – Mogden and Beckton by 2012 – Crossness by 2014
Objectives of the Improvements � Greatly reduce potential for storm sewage discharge into the River Thames � Less use of storm tanks to hold wastewater � Greater volume of sewage receiving full treatment � Improved dissolved oxygen levels in the River Thames The proposed improvements will ensure we continue to improve the Tidal Thames water quality
Proposed Improvements at Mogden � Modifications to existing plant and the construction of new plant within our operational land. � The main features of the proposed improvements are: - new inlet take off and new primary treatment tanks. - new aeration unit and new final settlement tanks. - sludge treatment improvements, including creating additional renewable energy. - odour control. - re-profiled embankments and new landscaping.
Preferred Solution for Mogden LEGEND Area of development. Other land in applicants ownership. Buildings. Site roads / hardstanding. Above ground structures. New & re-profiled embankment. Soft landscaped areas. Earth retaining wall.
Timescales � Summer 2007: Submit planning application. � Spring 2008: Anticipated construction date. � Spring 2012: Planned completion. This programme is in line with the completion date agreed with Ofwat.
Planning Application � Submit planning application to the London Borough of Hounslow - Summer 2007. � Includes Environmental Statement and Sustainability Statement. � Consultation with local residents, business and other organisations.
Planning Policy Considerations � Amenity, including odour and dust � Ecology and landscape designations � Construction traffic � Sustainability and energy
Environmental Considerations � Proximity to residents � Visual impact � Ecology and nature conservation � Spoil removal
Consulting and Informing � Staffed information display – 29 th May 2007 to 2 nd June, Whitton Public Library and 4 th June 2007 to 9 th June at lsleworth Public Library. � Newsletters � Website � Meetings and Presentations
Summary The proposed improvements at Mogden will:- � significantly reduce the potential for untreated or partially treated discharges to the River Thames. � ensure improvements in the water quality of the Tidal Thames. � reduce the use of storm tanks within the STW.
Tidal Thames Quality Improvements Mogden Sewage Treatment Works May 2007 Thank You and Any Questions?
Thames Tideway Strategic Study (TTSS) � The Independent TTSS* set up to: – consider the environmental impact of storm discharges to the Thames Tideway, and – propose potential solutions. � Objectives: 1. Reduce the amount of litter in the river 2. Protect the health of recreational water users 3. Protect the ecology of the Tideway � The objectives can only be fully met by: 1. Improvements to the tidal sewage treatment works, and 2. Constructing a new storage and transfer tunnel under the River Thames *www.thamestidewaystrategicstudy.co.uk
What are we doing now to improve the Tidal Thames water quality? � Thames Water owns two barges, which on request from the Environment Agency inject oxygen (30 tonnes/day) into the water � Hydrogen peroxide can be dosed into the river to increase oxygen levels in areas inaccessible to the barges. � Trash screens have been installed at critical sites. � Introducing new ‘skimmer’ boats (75ft x 25ft) to remove surface litter after heavy storms.
Proposed Tideway Tunnel Option 1c – 7.2m diameter Storage tunnel � Main Tunnel 32.2km long � Link Tunnel 5.5km long � up to 80m deep � pumped outlet to treatment � Time to empty – 48hrs
Building a new storage and transfer tunnel under the River Thames � The TTSS and the updated optioneering studies carried out at the request of Government concluded that a Tideway Tunnel should be built to intercept and store discharges from the Combined Sewer Overflows (CSOs). � The Tideway Tunnel – Transfer storm sewage from the CSOs to East London (Beckton) for treatment, including a direct link from Abbey Mills to Beckton. – 35km in length and 7.2m wide – Estimated cost of £2.1 billion – 12 years to construct. � TTSS identified 36 (of 57) CSOs to be intercepted by the Tunnel. The remaining 21 require no immediate action as they do not operate frequently or cause significant adverse environmental impact.
Ealing 08 – Location Map � Location: Brentford � London Borough: Hounslow � Area: 0.70km 2 � Current Mains Length: 18.77 km � Bursts/1000km/year: xxx � Property Count: 4250
Ealing 07 – Location Map � Location: Little Ealing � London Borough: Hounslow Ealing � Area: 0.75km 2 � Current Mains Length: 16.28 km � Bursts/1000km/year: xxx � Property Count: 3183
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