Tidal Thames Quality Improvements Mogden Sewage Treatment Works May - - PowerPoint PPT Presentation

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 Brent River Lea River Roding River Beam River Ingrebourne Thames Estuary Southend Gravesend Long Reach Riverside Crossness Beckton Mogden Barrier

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

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. LEGEND

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

• rganisations.

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 – 29th May 2007 to 2nd

June, Whitton Public Library and 4th June 2007 to 9th 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.

Storage tunnel Main Tunnel 32.2km long Link Tunnel 5.5km long up to 80m deep pumped outlet to treatment Time to empty – 48hrs Option 1c – 7.2m diameter

Proposed Tideway Tunnel

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

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