Asset maintenance - a healthy approach

Water and waste water assets are key integral elements of a business, Danny Heffernan explains why taking care of waste water infrastructure is good business

MUCH has been written about the leaking drains at the Institute for Animal Health’s (IAH) Pirbright laboratories in Surrey, leaks which led to the most recent outbreak of foot and mouth disease (Laboratory News April 2008). The report from the HSE makes specific reference to cracked drainage pipes as probably being the contributing factor to the outbreak. The report states "...such was the condition in which we found the site drainage system that we conclude that the requirements for Containment Level 4 were not met, thus constituting a breach of bio-security for the Pirbright site as a whole. Our conclusion is supported by the evidence we found long-term damage and leakage, including cracked pipes, unsealed manholes and tree root ingress..." 

Waste products from the chemical and biological related industries can be environmentally hazardous and when drained or stored in pipes. There is a risk that the pipes can become corroded causing fluids to escape and pollute water courses resulting in heavy fines from the Environment Agency. Also, after years of heavy use sewers, drainage pipes, drains, manholes, chambers and other water and waste water retaining storage assets can become weakened, if they are not maintained it can lead to collapses, blockages and costly repairs. Such disruptions can occur for numerous reasons but are frequently linked to badly maintained water and waste water assets.

Problems can also occur, for a variety of other reasons such as: changes in ground or traffic loading, leading to cracking and collapse, transfer of corrosive liquids causing erosion and corrosion of the pipe and chamber fabric, allowing exfiltration or infiltration.

Another major enemy in sewers is hydrogen sulphide, it attacks concrete and mortar above the liquid level in pipes and chambers causing it to deteriorate and fail. Hydrogen sulphide (H2S) which naturally occurs within sewer silts for example, can severely corrode both pipes and chambers actually eating into the concrete and mortar above the liquid flow levels.

This situation alone can give rise to major problems; however, when this is combined with production effluent it can be a recipe for disaster if allowed to continue unmonitored. The chemical cocktail within the effluent has a similar effect below the liquid level as the H2S does above, placing the entire system at risk. It remains essential that all foul water or other aggressive waste transfer systems remain both functional and isolated (sealed). Infiltration of ground or surface water can lead to additional costs by increasing the volume of waste being treated.

It is extremely important that these assets are inspected and effectively maintained on a regular basis to minimise any potential disruption to the business and its processes. Monitoring and maintaining assets need not be costly when carried out in a proactive rather than reactive manner by reputable specialist contractors.

One such specialist contractor is Ferro Monk Systems Limited (FMS). FMS have been specialists in the field of water and waste water asset rehabilitation for almost 30 years. Working closely with a very diverse range of clients throughout the UK and abroad such as water companies, drainage boards, laboratories,  petrochemical companies, brewers and distillers, food and drink manufacturers, chemical manufacturers and The Environment Agency.

The first step that needs to be taken in ascertaining the condition of any water

Ultracoat Spraying can create a new pipe within the old

or waste water asset is cleaning and inspection. In many instances this can be carried out remotely using specialist CCTV and high pressure water jetting equipment. It is essential that suitably trained and experienced personnel are employed to view the resultant survey recordings and decide what, if any, actions may be required.

There are two main methods used for rehabilitating, renovating or repairing systems and these are Man Entry and Non Man Entry. Man Entry Systems, as the name suggests, are carried out by operatives physically entering the pipes, culverts, tunnels, tanks or chambers to carry out the rehabilitation.

Techniques include FMS’ own patented Ferrocement lining which in the case of pipes, culverts and tunnels, involves the design and manufacture of pre-cast Ferrocement (Cement Mortar) inverts which are grouted into place within the existing structure. In most cases this acts as a flume to maintain existing, dry weather flows, cancelling the need for costly over pumping whilst the system is being worked on. This is followed by the installation of layers of reinforcement, governed by design, to the remaining perimeter of the structure and then encapsulated in Ferrocement by spraying and trowelling in situ. Chambers and tanks can be treated in much the same way.

Other techniques include Glass Reinforced Plastic Lining (GRP). This is a system which uses GRP manufactured units to a given size and thickness being installed within the existing structure to be rehabilitated

More recently, a 100% solids epoxy sprayed lining system called Ultracoat has become available - mainly in response to calls for environmentally friendly solutions. 100% solid systems contain no Volatile Organic Compounds (VOCs) and can be used to rehabilitate waste water systems within confined spaces with no risk of combustion to hazardous materials. It is highly resistant to aggressive effluent, algae and bacterial growth. Because it can tolerate high temperatures, and high levels of sulphur dioxide, acids and alkali, it can also be sprayed onto damp surfaces and applied quickly, bonding well. Assets can be back in use within as little as two hours after application.

The high bond strength of the 100% solid system means it can strengthen corroded or weakened structures and adheres well to most surfaces, including concrete, steel, brick, fibreglass and clay. It can be used in tanks, chambers, manholes and culverts. The solution is an exceptionally versatile substance, which when sprayed in situ, will take the shape of the substrate.

Non Man Entry, often called ‘No Dig Technology’ or ‘Trenchless Technology’ and also technically known as Type II Linings, is a methodology which employs remote techniques and equipment to carry out the necessary rehabilitations, renovations or repairs, carried out using existing accesses such as manholes, saving costly excavations.

Type II linings are placed into a structural pipe without requiring a bond with the existing sewer. There are now a number of systems on the market, the main types being based around a resin impregnated felt tube or sock. The resins become cured either through exposure to increased temperature (using hot water or steam), or ultra violet light.

Syngenta, one of the UK’s main specialist producers of agricultural chemicals, fully understands the need for planned inspection and maintenance and has over a number of years worked very closely with FMS to ensure that any issues associated with their drainage and storage systems are identified at an early stage. Once identified any issues can be dealt with quickly and cost effectively, thus reducing any possibility of a shut down, which, when not planned can be very costly indeed.

Operations at Syngenta in Huddersfield have benefited from FMS rehabilitation solutions over the years including CCTV inspection services, manhole to manhole full length lining and short sleeve patch repairs to cracked and effected drainage pipes.

For example the company introduced an acid resistant Cured In Place Lining System (CIPP) which uses specialist vinylester resins to combat and resist aggressive effluent in pipes. CIPP is a Water Research Council (WRc) approved Type II lining system designed and installed in compliance with water industry specification 04-34-04. Developed to withstand either an external static water head (i.e. ground water level) or ground and traffic loading.

This fully approved and designed technique, for full or part length, manhole to manhole relining of pipes and culverts uses resin impregnated polyester felt lining tubes to effectively create a new pipe within the old, bridging gaps and holes in damaged pipes and sealing cracks in most shapes and diameters. Ranging from 150mm to 1200mm, the system can breath new life into pipes, creating a continuous pipe without any joints. Even lateral connections can be reconnected into the newly lined pipes by using state of the art remotely controlled robotic cutting equipment.

Many systems are based upon the use of an epoxy impregnated medium, such as glass fibre matting, which is wrapped around an inflatable packer. The system is introduced into the sewer, positioned at the point of repair (allowing sufficient overlap into the defect free host) and the packer inflated, pushing the patch against the pipe. Following cure, the packer is deflated and recovered for re-use.

Maintenance of water and waste water assets need not be costly if dealt with a timely and correct manner, however, it is essential to seek the advice from a specialist company. Identifying problems early can prevent major, often expensive disruption to business. Proactive planned inspections can be the key - reactive action can often be too late when the unexpected flooding, pollution, collapse and stoppage of production has already happened.