Manhole Repair and Rehabilitation
Applies to wet wells and pump stations and similar structures.
The UK has a wide range of manhole types, mainly concrete and brick construction, installed over the years.
Manholes can be found in all types of infrastructure, Sewers and drains, surface water control, industrial plants of all types, chemical plants, foods processing plants, breweries, refineries etc. etc.
Why do manholes need relining?
Older manholes were made from engineering and vitrified brick that have excellent resistance to chemicals and in particular sulphuric acid, formed from the H2S gas generated by microbiological activity in sewage. These bricks were excellent when first used in the construction of manholes. Unfortunately the cement mortar mix used to bond the bricks together has poor resistance to H2S and chemical attack, the mortar joints are attacked by the chemicals and any H2S gas generated and the mortar can be significantly reduced its strength and consequently affecting the bonding of the bricks and the structural integrity of the manhole.
Similarly chemical and H2S attacks on unprotected concrete manholes react in the same way, attacking the cement in the concrete and reducing its strength, dissolving the bond between the aggregate, sand and cement mix resulting in the eroding the surface and exposing rebar in some extreme cases.
How do I know if a manhole should be repaired or not?
The symptoms of this type of damage to manholes are displayed as infiltration issues (through brick joints, concrete ring joints, penetrations) causing overcharging of the downstream treatment plants, exfiltration leading to pollution and environmental issues, structural failure, damage or complete destruction to the concrete benching and pipe connections, wash out of backfill and surrounding ground subsidence.
We have solutions for all aspects of dealing with manhole, pump station and wet well problems.
We visit site, survey and examine the problem, (all our operatives are confined spaces certified), we will recommend and quote for a solution to the problems identified that can include;
- Leak sealing.
- Preparation and cleaning of the manhole surfaces.
- Repair of benching, mortar joints, replace missing concrete, repair and restore and protect re-bar.
- Application of protective coating.
- Check and sign off and issue guarantee for completed work.