Parts of a Manhole
A manhole typically consists of a manhole chamber or ring, which is a vertical circular pipe and is used to access inspection points. The cover itself can be circular, rectangular, or a rectangle or square made of two detachable triangles, and is made from materials ranging from concrete to fibreglass.
The rings themselves come in a range of sizes and depths to accommodate the actual depth of the site from ground up. Approved sealants are used to seal manholes in order to make them watertight. Unless the depth of the manhole is less than a metre, step ladders are mandatory; however, if the depth exceeds two and a half metres, it gets fitted with a regular ladder. Depending on the size and depth of the manhole, a concrete surround may be required. The rings must be backfilled with boulder-free, granular material.
Building Over Manholes
While the building control department of local councils are responsible for who builds what over manholes and sewers, you need to consult and acquire the consent of the water authority officials of your locality as well before you decide to do anything about it
As a general rule, permission is needed to either build over or anywhere near three meters of a public or private manhole. Furthermore, permission will not be granted for building directly over manholes; or for that matter, over pressurized pumping mains. This is because the added weight of a new structure over them could cause damage to the sewage system, besides leading to problems in the drainage systems of the surrounding properties. However, you can check with officials to see if diversion of the sewer is possible; at your expense, of course.
Additionally, in case maintenance work, inspection or repairs, clearing debris, excavation or rodding needs to be carried out, there should be no hindrance getting to the manholes as they are the points of access to all the chief drainage lines.
Manholes should never be confined as they are often dangerous and may contain poisonous gases. Therefore, covering those up would cause these gases to accumulate in the immediate vicinity and the escaping gases in the absence of open spaces for safe disbursal could be fatal.
Manhole Horror Stories
As recently as 21st August 2014, three-year-old Oliver Akenhead narrowly missed falling down a drain as the manhole he stepped on in a grassy children’s play area gave way. By luck, he threw up his arms and was able to stop himself from going all the way down; hearing his frightened cries, passers-by and his eight-year-old sister pulled him up.
His upset parents are calling for more checks to be carried out on manholes. Northumbrian Water, the company responsible for the maintenance of the manhole, cemented the lid in place the very same day. In order to prevent tragic accidents the company has appealed to the public to immediately notify them if they were to come across faulty manholes.
Elsewhere, there are numerous other horror moments captured on film.
Express Drainage Solutions are the leading providers of drain and sewer unblocking and repair services across London and the South East. Our expert team utilise CCTV inspections in order to get to the cause of the damage, and our high pressure jetting services are ideal for clearing all blockages.