Module 3: Drain Serviceability & Scoping WRc condition grades A/B/C, defect identification

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The reasons for the site investigations.

We need to investigate a reported problem so we know where the fault is located.

We can then unblock the specific run, gully, w/c, and address the fault head on.

Once we’ve identified the problem area we can then restrict our CCTV survey to this without having to survey the complete drainage system

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Discuss with group how to identify a problem area so we can target our investigation.

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Go through typical equipment on the van with the group and what it does.

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By nature drainage systems are found underground and at one time, the location and rectification of the fault were very much “hit and miss”.

If we take the example that as little as 20 years ago a householder discovered that their drainage system was blocked they would probably have called out a local plumber or builder who would have tried to unblock the system using his drain rods.

If it was impossible to clear the blockage, and a collapse was suspected, then the only way to locate the point of the suspected collapse would be to measure off how many drain rods were inserted into the underground drain, this distance would then be marked at ground level and excavations undertaken where the fault was assumed to be.

This process was neither accurate nor cost effective as the underground drain could bend in any direction, resulting in the plumber/builder excavating in entirely the wrong place.

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In more recent years the technological advancement in fault identification and location products has revolutionised the drainage industry. Through the continued use of one or several of the following items we are now able to detect and locate the source of the problem more accurately than ever before:

CCTV Inspection - Giving a picture quality comparable to that of a hand held camcorder, this “underground eye” give the trained CCTV operative not only the ability to accurately identify a faulting area of piping (within an entire drainage system), but also measures the location of the underground fault to within a fraction of a metre. This results in a more cost-effective solution to drainage rehabilitation as repair specifications can be accurately made on a measure basis instead of the old “hit and miss” approach.

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Drainage issues usually involve a blockage, smells or ingress of water within the property.

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Air or water pressure tests are undertaken, normally as part of checks made on subsidence claims, to check the air or water tightness of a drain.

In the case of air tests, cloth covered rubber bags are usually placed at the two ends of a drain run and then inflated. The air pressure between the bags is then measure, recorded and calculated to determine whether remedial attention is required.

Similarly in the case of water tests, expandable steel/rubber stoppers are placed at the two ends of a drain run and then the line is flooded. Dependant upon the extent of water loss remedial attention may/may not be required.

It is important to realise that any drain put under air or water pressure tests is expected to fail to a slight degree as it is recognised that it is impossible to install a completely and air/water tight drain. The British Standards Institute and other industry leading bodies accept the reasons for this “leakage”.

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Is there any history of subsidence in the area? (Road, Street, Estate, Village, Town ETC.)

Has the customer experienced any drainage problems?

All information must be logged accurately.

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A site plan is a technical drawing that depicts the information on site.

It is used as a point of reference

Site plans are used by Claims handlers, Insurance Companies, County Councils, Utility Companies, The Ombudsman, Structural Engineers, Planning officers, Repair teams.

Discuss with the group the site plan including what the different types of lines mean and the flow arrows.

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Explain the difference between a crack and a fracture

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The are many different types of coding sheet. This is a typical example.

Go through the sheet with the team explaining what everything means.

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The Drain Repair Book has been developed at the request of the Drainage Forum; a group of insurance companies that are all members of the Association of British Insurers. Collectively they recognise that there is scope to improve the quality of repairs in the domestic drainage industry, and the effectiveness of all those who work within that industry by identifying and promoting best practice. It serves both as a guide to Drainage Specialists carrying out inspection and repair work, and to assist the insurance industry and others in auditing the work.

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Tree Roots - Two different mechanisms of tree root damage. Roots getting into the drain and larger roots putting pressure on a drain. Generally, tree root damage is accepted by insurers as Accidental Damage. However, if the property is over 50 years old and there are no broken or cracked pipes and fine roots have penetrated most joints, it could be argued this is wear & tear or gradually operating cause. Insurers may not be prepared to support us, at this time, so we need to try to improve their and/or the Ombudsman's understanding! Always check Policy wording

Vehicle Pressure - Where vehicles have damaged a drains by driving over them.

Ground Movement - Difficult to accurately diagnose. All ground moves seasonally to some degree, this effect decreases with depth. Correctly laid drains should cope with minor movements. If pipes are fractured insurers will generally accept ground movement as AD. Where the joints are open, mis-aligned or a drain is holding water it is sometimes difficult to say whether this is ground movement or was laid like this.

Physical Damage -

Foreign objects in the pipe (e.g. Childs toy, builder’s debris, builders operations, rods stuck) if the pipe is damaged this is AD but if just a blockage it depends on policy wording, but is generally covered.

Drain hit by spade, fence post or over enthusiastic rodding & broken, this is AD

Undermined by leakage - Again this can be difficult to diagnose. Water leaking from one joint or fitting may wash away support and undermine adjoining sections causing them to move and fail. This would generally be accepted as AD

External Force - Generally excessive pressure on a pipe from some structure (e.g. large garden wall, foundation, conservatory etc). Would be AD unless we can show it was due to defective installation and there is specific policy exclusion for this.

One Off Blockage - Covered as AD by most insurers, unless the policy specifically excludes it.

Poor Installation - If this is clear-cut & we can prove it, most insurers would not accept this as AD. If specifically excluded then it should be declined (or repudiated - insurance terminology for not paying a claim). This may often be the cause of many problems with septic tanks or Soakaways. It also could apply to -

pipes laid through or under walls but not properly protected

Pipes laid to incorrect falls

Displaced & open joints

Poor maintenance - Loose, broken or eroded mortar joints or benching in manholes. Again many septic tank problems. Not AD

Misuse - Disposable nappies/ sanitary towels. According to the Ombudsman, the disposal of anything where the policyholder should know that a blockage is likely. Not AD

Pitch Fibre Pipes - Have a limited life 25-40 years. Each case needs consideration on its own merits. Insurers and the Ombudsman appear confused on this.

If it is clear that damage is due to weight of vehicles or roots etc, this is accepted as AD.

If delamination &/or distortion but pipe is still serviceable, then probably not AD, but in reality it depends on policy wording & insurers attitude. It can become difficult when many properties are sharing & some accept the claim & some don’t.

Other - Wear & tear!

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Usually cleared by rodding or jetting. The policyholder would be advised on misuse of the drainage system.

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Jetting is used to remove fats and grease, rods can be retrieved as long as they aren't wedged stuck.

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For unserviceable defects excavation or if possible root cutting and lining is required based on the most cost effective option and disruption to the homeowner.

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Vehicle Pressure and Ground Movement the likely causes. For unserviceable defects excavation or if possible lining is required based on the most cost effective option and disruption to the homeowner.

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For unserviceable defects re-rounding and lining or excavation are required based on most cost effective option and disruption to the homeowner.

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Excavation is usually the best option for poor workmanship to put the defects right however lining may be an option in some cases.

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Third parties unaware of drains in the area often damage the drains when carrying out works of their own. We would look to pursue a recovery if the third party details were known.