coulsdon ‘cloudy water’ remedial works - ses water - home remedial work… · ·...

Sutton and East Surrey Water plc, London Road, Redhill, Surrey RH1 1LJ

2 February 2015

Coulsdon ‘cloudy water’ remedial works

Thank you for attending this Drop-in event which aims to explain the various remedial

methods we will be employing, both in the short and long term, to provide a lasting solution

to the problem of ‘cloudy water’ in the Coulsdon area. A brief description of these methods is

included below.

I hope you will take the opportunity to speak to our experienced project engineers, water

quality and customer services representatives who will be happy to answer all your

questions. A detailed Questions and Answers leaflet is also included with this leaflet.

Throughout the remedial works programme we will be keeping you updated via regular

newsletters, and online at www.waterplc.com/coulsdon.

Lastly, I would like to thank you again for your continued patience.

Yours sincerely

Anthony Ferrar

Managing Directror

Ice Pigging is a patented process for cleaning the inside of pipes using slush ice. It is fast, effective and low risk, using significantly less water than most other techniques for cleaning techniques. Ice Pigging was developed in the UK but is now widely adopted as the most cost-effective method of pipe cleaning in many countries around the world. Benefits include:

• Uses 50% less water than flushing

• Is up to 1000 times more effective at removing sediment than traditional mains cleaning

• Flows through all diameters, fittings and bends of pipes

• Significantly reduces customer disruption because it’s a quick operation

• Takes half the time that is normally required by other techniques, with the pipe typically isolated for only 30 to 180 mins (depending on length of run)

• Generally requires no excavations: a genuine ‘no-dig’ technique

• Low risk – if ice were ever to get stuck it will simply melt

• Ice is harmless to public health

Ice and sediment is removed via hydrant

Ice slurry is pumped into the pipe via hydrant

The valve is fully closed

The ice is pushed through the pipe using the mains

water pressure


Replacing a water main

Typically, there are four separate stages involved in replacing a water main, some or all of which may be used during our remedial works in Coulsdon: Stage 1: Lay the new main Stage 2: Test for quality Stage 3: Transfer property

supply pipes Stage 4: Disconnect the old main Stage 1: Lay the new main Two techniques are considered when replacing a water main depending on conditions – either ‘open dig’ or ‘trenchless excavation’. Sometimes we use a combination of both.Trenchless methods still need some excavation work, but the amount of digging is significantly reduced.

Stage 2: Test for quality The new main has to be sterilised and pressure-tested, and the water quality checked, before it can be connected to the mains network. During this stage, it may appear that not much is happening on site. However, back at our laboratory, scientists will be busy carrying out detailed technical analysis of water samples to make sure the new main is clean and sterile. We will also be pressure testing the new main to guarantee that the workmanship of our contractors meets our strict standards and there are no leaks.

Stage 3: Transfer property supply pipes To transfer from an old main to the new one, a new service pipe is laid from the main as far as a property’s existing stopcock, typically located at the property boundary. The existing stopcock is removed and the new service pipe connected. If you have a water meter it will be transferred to the new supply. If you don’t have a meter but would like one, it can easily be fitted into the chamber housing the new stopcock.

Stage 4: Disconnect the old main Once all properties have been connected, the old main can be decommissioned. It remains in the ground as it is not cost effective, or necessary, to remove it. But its position is recorded so other utilities are aware it is no longer in use.


Coulsdon ‘cloudy water’ remedial works

If you would like more detail about any of the techniques described in this leaflet or would like more information about the project itself, please contact our

Customer Services Team on 01737 772000 Office hours: 8:30am to 5:00pm Monday to Friday

Website: www.waterplc.com Telephone: 01737 772000 Email: [email protected]


2 February 2015

Questions and Answers

Q: What caused the cloudy water? A: The cloudy water was caused by the disturbance of chalk deposits in the mains network.

Normally these deposits sit in parts of the network where they lie undisturbed and the water flows past without impact. However, in a ‘shock’ event like the one that occurred when the supply was interrupted on 25 November last year, these fine particle deposits got picked up in the water supply. The shock event occurred following damage to one of our large diameter mains by a telecoms contractor.

Q: Where did the chalk in the main come from? A: The water supplied to your area comes from local boreholes dug deep into the ground. The

untreated sources are naturally hard waters due to the calcium salts which dissolve in the water as it percolates through the chalk underground ,. We partially soften the water but the treatment process itself can produce chalk particles (calcium carbonate) which we then have to remove by filtration before the water is distributed to customers. Although the water supplied no longer contains chalk particles, the treatment processes in the past were not as efficient at removing the chalk particles and so some chalk particles did pass into the distribution network.

Q: What are you doing to resolve the problem? A: We have been closely monitoring flows and testing the water quality since the incident

occurred. Whilst our results have shown that the situation has been slowly improving our engineers have now reviewed the whole of the water supply network in the Coulsdon area and will be carrying out a programme of planned remedial works designed to provide a lasting solution.

Q: What do the remedial works involve? A: We will be carrying out a five-Phase plan of remedial works involving Ice Pigging, flushing and

mains replacement. Q: When will the remedial works begin and how long will they take? A: Phase 1 which involves Ice Pigging will take place on Wednesday 4 February. The other

Phases will follow shortly afterwards. We will be keeping you up-to-date on progress on the dedicated web page at www.waterplc.com/coulsdon and via regular newsletters.

Q: What is Ice Pigging? A: Ice Pigging is a patented process for cleaning the inside of pipes using slush ice. It is fast,

effective and low risk, using significantly less water than most other techniques for cleaning water supply pipes. Ice Pigging was developed in the UK but is now widely adopted as the most cost-effective method of pipe cleaning in many countries around the world.

Q: What is Flushing? A: As the name suggests, flushing is the purging of the water mains network by flushing through

the water mains and releasing the water from a hydrant or washout. The flushing generates the velocities to pick up the chalk sediment.

Q: Will our water supplies be turned off whilst flushing/pigging takes place? A: Your water supply will be briefly interrupted during this time and we strongly advise that you

avoid using any water until our work is complete. This includes showers, washing machines, dishwashers and any other water-using appliance. If you draw water during our operations it may result in particles entering your plumbing system.

Q. Will flushing/pigging be rolled out to the wider area? - A: Yes. We are carrying out a phased approach so that we can ensure that the water mains

network will be cleaned in a systematic fashion.


Useful contact details:

SESW Customer Services Team 01737 772000 [email protected] Sutton and East Surrey Water Services 020 3603 9913 [email protected] Haste Ltd (9:00am to 6:00pm) 01730 897100

[email protected]

WaterSafe (registered plumbers) www.watersafe.org.uk

coulsdon ‘cloudy water’ remedial works - ses water - home remedial work… · ·...

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