MANHOLE RENOVATION- THE KEY TO LONG-TERM WASTEWATER NETWORK DURABILITY

MC Construction Chemicals, along with its UK representative CJ Kelly Associates Ltd, is pleased to announce the launch of a new all-encompassing Manhole Renovation product range, ‘ombran’.

The most recent statistics, reported by some 27 countries across Europe, have shown that there are some 60 million manholes currently in operation. A further report showed that, of these manholes, around 12% (or 7.2 million) are in a state of deterioration to the point where renewal is required. Furthermore, cost estimates also showed that the average cost of fully rehabilitating one manhole is about €2,250. This equates to a total of around €16.2 billion for the 7.2 million manholes needing repair.

COST EFFECTIVE SOLUTION

For many years now sewerage engineers have known that the effective renovation of a sewer network relies as much on having a high standard of manhole condition as it does the pipelines connecting them. Over this time studies have highlighted increasing numbers of manholes are requiring renovation and that several aspects of manhole construction can lead to a variety of failure modes.

The most common defects found in deteriorated manholes include: 

Lowered manhole frames

Leaking manhole ring joints

Damaged access ladders

Cracked construction elements

Faulty or water-bearing pipe/liner bonding

Corroded concrete or exposed reinforcement

Damaged or washed out jointing

Wide-spread corroded concrete or brickwork

Wide-spread moisture penetration

Damaged flow trench, floor and benches.

This sort of damage can occur for a number of reasons ranging from frost damage and loading stresses to chemical attack by components of the waste flowing through the pipes and simple deterioration of the construction materials with age.

A good manhole renovation system needs to address all such defects not just a few.

This is why MC Construction Chemicals has developed ombran as a solution to manhole and sewer pipe deterioration.

OMBRAN

The ombran system comprises a number of different materials each with a particular property which offers a solution to a particular problem. The products work across of range of chemical conditions from the acidic to the highly alkaline. They offer properties for the long-term waterproofing of the structure, an ability to re-profile the structure and to adjust and strengthen the construction of the manhole frame itself.

The ombran product range includes: 

ombran SVG

ombran W

ombran R

ombran HB

ombran MHP

ombran ASP

ombran IW

ombran SVG is grouting mortar particularly suited to the repair and reconstruction of manhole frames.

ombran W has been designed for use in leaking manhole ring joints. The product provides waterproofing against both infiltration of ground water and exfiltration of wastewater flows into the surrounding soils. It comprises a setting plug mortar. This product is also applicable where injection sealing is required where water-bearing cracks occur in the manhole structure, where ring spaces occur between the manhole structure or pipes occur or where an annulus exists between the host pipe and a liner.

ombran R has been developed to reset defective access rungs quickly and permanently into the wall of the manhole.

ombran HB is applicable to circumstances where damage has occurred to the flow trench, floor or benching in the manhole or where concrete has corroded and /or reinforcement metalwork has been exposed.

Similarly ombran MHP can be utilised where concrete/brick corrosion or reinforcement exposure as occurred, particularly where the corrosion is wide-spread. It is particularly useful where the highly acid or alkaline environments exist as its operating range is between pH3.5 and pH14.

Where wide-spread material corrosion exists ombran ASP may also have application. In this instance the product has a chemical range between pH5 and pH11.

ombran IW is applied where there is wide-spread moisture penetration of the manhole structure materials. ombran IW is a product which offers permanent pore sealing as the product swells.

 

APPLICATION

To achieve the best sealing and repair solution of the defective manhole several steps have to be correctly followed. First the old surface must be properly prepared. Effective surface cleaning to remove loose materials such as dust, grease, oils and any other contaminants is paramount.

The structure must then be waterproofed using either ombran IW or ombran W and the appropriate application device or method.

Once waterproofing has been achieved any re-profiling of the structure should be undertaken where extreme unevenness, intrusions or deteriorated concrete/brick surfaces occur. This reconstructs the required geometry of the original manhole design so allowing it operate more effectively.

The top coating is then chosen in accordance with the future expected operating conditions such as acidity, aggressiveness and varying flows of the wastewater within the structure. This would normally require the use of ombran ASP or ombran MHP depending on the chemical regime and range expected.

Curing of the ombran materials is as important as the correct selection in the first place. Curing must be achieved by protecting the coating to prevent too rapid a drying process. This is not just to protect the final surface within the manhole to also to enable the full bond to be achieved between top coat and previously applied materials.

A typical standard installation comprises some 4 applications. After full cleaning of the old manhole surface has been achieved an initial bond coat, typically ombran HB, is applied to ensure any further coatings hold firm. The re-profiling coat, typically ombran R or ombran MHP, is then applied to reshape the manhole structure to that required for efficient operation. A further bond coat is then applied to ensure that the top sealing coat, typically ombran ASP or ombran MHP, has a solid hold fully sealing the structure for decades to come.

Whilst this is a typical solution for the average defective manhole, the ombran system is also very flexible and MC’s engineers and representatives can advise on and adapt the installation to suit almost any circumstances that might be encountered in a deteriorated manhole.

Commenting on the introduction of the full ombran range to the UK manhole renovation market, John Kelly of CJ Kelly Associates Ltd said: “For many years one of the major drawbacks with pipeline renovation has been that whilst lining repairs pipe it can omit the manhole from the renovation equation. Yet, it is in the manhole that a lot of the leakage problems occur. It is therefore essential that to renovate a pipe network as a whole the manhole must be included. The ombran system offers a range of products that will address virtually any circumstance within the manhole where deterioration has occurred without the need to use numerous suppliers.”

For a free technical binder please email  HYPERLINK "mailto:martyn@cjkelly.co.uk" martyn@cjkelly.co.uk or call 01832 293030

For further details please contact:

CJ Kelly Associates Ltd

Coppice House, Main Street, Hemington, Peterborough PE8 5QJ, UK

Tel: +44 (0)1832 293030. Fax: +44 (0)1832 293311