Thames Water

Mogden Sewage Treatment Works

Residents’ Liaison Meeting

01 April 2009

Thames Water

Agenda

Review of previous minutes

Operations and correspondence

Mosquitoes and the Mosquito Campaign 2009

The Odour Improvement Project and its independent review

Tidal Thames Quality Improvements Project

Communications

AOB

Thames Water

Operations and correspondence

Thames Water

Operational Correspondence

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OtherMosquitoesOdour and mosquitoesOdour

Thames Water

Mosquitoes and the mosquito campaign 2009

Thames Water

Controlling mosquitoes at Mogden (1)

We operate a strict all year-round mosquito survey and control programme

Surveys are carried out on a weekly basis by external experts in mosquito identification

The number of sites surveyed vary with mosquito breeding patterns

Winter – up to 60 sites

Summer - up to 250 sites

Thames Water

Mosquito data - Number of sites inspected

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Average 03-07 2008 2009

Thames Water

Controlling Mosquitoes at Mogden (2)We use a number of different methods to control mosquitoes

Physical - Removing stagnant water breeding sites, for example unblocking drains.

Biological - Using natural methods of control such as bacterial spraying of larvae

Mechanical - Using ultraviolet light traps that ‘zap’ insects with a high voltage electric shock

Chemicals - Using pesticides to kill adult mosquitoes

Regular control measures are implemented less than 2 days after the surveys are carried out

Thames Water

Mosquito data - Percentage of sites showing any activity

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Mosquito data - Percentage of sites showing any adults

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Mosquito data - Percentage of sites many adults

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Thames Water

Mosquito data - Percentage of with larvae activity

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Thames Water

Beating Biting Bugs campaign

In May we will be distributing our Beating Biting Bugs campaign leaflet to local residents around the works.

We are working closely with LB Hounslow and LB Richmond and plan to have an article in their resident publications later this summer.

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The Odour Improvement Project and its independent review

Thames Water

BackgroundAt our last price review in 2004, we included investment to reduce odour at

Mogden in our business plan. This was submitted to our regulator, Ofwat.

In their price determination in 2005 Ofwat allowed us to increase bills to customers in order to fund Mogden odour improvements. This was based on a 66% reduction of odour (measured against the 2003 odour survey).

The main scope of work was to cover the below key parts of the treatment process highlighted by an independent review, including:

Inlet Works (East and West side of Mogden)

Primary Settlement Tanks (East Side)

Two Storm Tanks (East Side)

We also installed 2 sets of equipment to extract and treat the odorous air, known as odour control units.

All of the above areas of odour control were designed to robustly comply with the requirements of the odour abatement notice.

Thames Water

Some examples of odour control

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The result

In September 2008, OdourNet carried out an odour survey to see if we have met the required reduction of odour.

The calculated reduction in site odour emissions determined by direct comparison showed the following:

90% reduction compared to the 2003 dataset

82% reduction compared to the 2005 dataset

Taking into account for variations in emissions from different plant across the works, the calculated ‘worst case’ shows the following :

72.9% reduction compared to the 2003 dataset

66.2% compared to the 2005 dataset

A full copy of this report is available on our website:

www.thameswater.co.uk/mogden

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Tidal Thames Quality Improvement Project

Thames Water

Background

Thames Water is investing in improving the water quality of the Tidal River Thames; for the ecology that thrives there, and everyone who uses and enjoys it.

The proposed site improvements will enable Mogden STW to cope better with increased flows caused by heavy periods of rain, or ‘storm conditions’.

This will mean a significant reduction in the need to discharge any untreated wastewater into the River Thames.

The improvements will also mean less use of the existing storm tanks.

The new works will be odour neutral

Thames Water

Latest

In March 2009, Hounslow Council approved the planning application for the proposed improvements to Mogden STW subject to the completion of a legal agreement and subject to a decision by the Mayor of London and referral to the Government Office for London.

We are encouraged by Hounslow planning committee’s recognition of the need to improve the quality of the Tidal Thames and their positive response to our proposed improvement works.

We will continue to work closely with the Council to finalise the legal agreement and meet the planning conditions.

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Communications

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Keeping up to date with MogdenE-Mail notifications

Informing residents of possible increase in odour

To subscribe, email us at mogden@thameswater.co.uk

Mogden Newsletter:

Next edition will covering the results of the Odour Improvement Project and the Tidal Thames Quality Improvements.

Mosquito Awareness Campaign 2009:

‘Beating Biting Bugs’

Thames Water

Find out more…There are a number of ways of contacting us to find out more information.

Call our Customer Centre, our lines are always open

0845 9200 800

Visit our regularly updated website

www.thameswater.co.uk/mogden

Send a letter to

Thames Water

PO Box 463

Swindon

SN38 1TU

Thames Water

A.O.B