Handy Information and Advice

Handy Information and Advice

Keeping You in the Loop





C.J Lyon will make every concerted attempt to produce a qualitative and quantitative survey, outlining all the significant observations and where applicable, the actions needed to fix and prevent a specific problem from reoccurring. However, we cannot accept any liability for any misinterpretation by third parties of the information contained in our reports. The conditions of the drains observed in a report are that of the day(s) of the survey only.

C.J Lyon uses the system ‘WinCan v8’, which uses the Sewer Rehabilitation Manual grading system for classifying pipes with a 0-5 scoring system under service and structural defect observations, where 0 means the pipes are in good condition, and 5 entails that they are in poor condition. This system is a screening process which is extremely useful for quickly assessing which pipes are in most need of remedial works. Additional care should be taken when interpreting these scores when working with plastic or renovated pipes.

The clock reference system is used to indicate where observations are being made, relative to the absolute position of the invert of the pipe. That is to say that the soffit of the pipe is at 12 o’clock, the invert of the pipe is at 6 o’clock, the right hand edge is at 3 o’clock and the left hand edge is at 9 o’clock. Where observations are made between points of the clock face, they are done so in a clockwise direction. I.e. from 3 to 9 o’clock is the bottom half of the pipe.

Unless stated otherwise, all invert depths are measured at the downstream end of the inspection chamber or manhole, vertically from the bottom of the channel to the top of the manhole cover.  The ‘master’ copy of the recording for a report will be kept at C.J Lyon for a period of 24 months from the date of the survey, and further copies may be available to purchase on request. After this time, the master copy may be destroyed.

There are a few different kinds of pipes that will be found in drainage systems, and all are slightly different in the way that they handle environmental factors (e.g. ground pressure).
Clay pipes are the traditional type of drain pipe and are found at properties of all ages, but particularly properties built before the 1960’s. Older clay ware piping systems typically used socket and spigot joints that were caulked with lime mortar to provide a rigid string of drains. These older systems are commonly found to be cracked and broken due to the inflexibility of the joints coupled with slight ground movements, and have never had any degree of built in design-flex.

Old cast iron pipes are susceptible to considerable erosion during service, poor hydraulic performance due to rough internal surfaces and poorly constructed connections to clay or other pipe materials. Modern versions of vitrified clay pipes and uPVC (plastic) pipes are jointed with polymeric flexible couplings, which allow the pipes in the ground to adapt to slight ground movements without

 

 

 


breaking. The modern joints can be susceptible to leakage and root intrusions as their older counterparts, but often as a result of poor installation, overloading, excessive ground movement or direct damage.
As a whole however, they are a significant improvement on clay and cast iron pipes and so should sustain somewhat less damage if exposed to these elements.

Another type of pipe used in the 1940s, 50s and 60s was a type called a Pitch Fibre pipe; this was used in a large scale by the UK construction industry. These pipes are not used anymore, due to them being found delaminated, blistered and deformed, as they deteriorate under ground pressure and in damp conditions such as those found in drains.

The jointing systems of all below ground pipes are always constructed around the outside of the pipes, so are not usually visible on CCTV recordings. Hence, a detailed knowledge of past and present drainage construction techniques is usually used to draw conclusions about the integrity of the pipe joints, from the conditions observed on their inside surfaces.

A common problem is root intrusion into drains, but this only usually occurs when there is an existing defect such as a crack, fracture or a hole in the pipe. Roots from trees and shrubs naturally seek out water and nutrients, so when they find entry into a drain or sewer, they often fill the available space to make best use of the available water, and this can lead to some considerable blockages if left unchecked. Drains with root intrusion can often be repaired permanently without the need for excavation and removing the tree/shrub from the pipe, however at C.J Lyon we do not recommend leaving the offending materials in the pipe, and prefer to excavate and repair where necessary.

It is an offence to let anything enter into the public sewer that might cause a problem to the flow of the sewage, or that causes a problem with processing at the local waste water treatment plant. These objects include not only gravel, bricks or any other solid object, but also fats, oils and greases. (Section 111 of the 1991 Water Industry Act; Section 46 of the 1968 Sewerage Act in Scotland).

Under legislation enacted on 1st October 2011 in England and Wales, all previous private sewers and private lateral drains have now passed into the ownership of the local Water and Sewerage Company (United Utilities in the North West). At the present time, there are a few exceptions to this ruling which includes drains and sewers under Crown land, some pipes under Railway land, surface water pipes that lead directly to a moving water course and pipe systems upstream from and including sewage pumping stations. Under the new rules, pipes that were previously deemed to be ‘Section 24’  sewers are now public sewers under the ownership of the local Water and Sewerage Company (e.g. United Utilities).