DALROD UK Ltd, with offices in both Peterborough (Head Office) and St Ives (Cambridgeshire) and depots across East Anglia, the Midlands and the North East of England, has once again proved itself as a leader in the drainage maintenance and repair field by successfully completing a technically challenging job, with the minimum of disruption, close to historic Ely Cathedral, using trenchless lining techniques.
The problem was that some 5 years ago pipeline survey works highlighted that ground movement has caused deterioration and cracking in sewers the vicinity of the cathedral, with the situation being carefully monitored by DALROD since. A more recent survey indicated that the sewers were now in need of relining, which is normally a straightforward procedure for the DALROD team. However, in this instance, one particular 225 mm (9 in) diameter sewer system, which was approximately 2.8 to 3.0 metres deep, had particularly difficult access problems. The access was tricky for various reasons including that the pipeline runs below a terrace of pre-war-built houses with no rodable access points from most of the lateral connections as well as poor access to most of the gardens of each individual property which made it difficult to reopen the lateral connections subsequent to the main line lining work. In addition to the access difficulties, most of the properties comprised 3-storey buildings that had live systems which could not be shut down adding to the general operational difficulties. All of this meant that Dal Rod had to reline the sewers whilst the system was live and over-pump where flows required it to make sure that no flooding occurred in the basements of any of the 3-storey buildings during the works. This was clearly a case for a trenchless lining or 'no-dig' solution. Having examined the options it was decided that Brawoliner was best suited to the work, a system which the DALROD team had previously utilised on similar jobs.
DALROD’s lining expert, Mike Pollard, said “We knew that only one product would do the job and that was Brawoliner as it is a strong, flexible material which would fill all of the cavities, smooth out joint displacements preventing any further movement within the sewer itself. Not only that but it also meant that we would eliminate the need for expensive excavations.” In this instance, Brawoliner was chosen because of its capacity to negotiate multiple bend and joint displacement situations whilst offering a 50+ year life-expectancy.
DALROD is one of a number of contractors in the UK that have attended the Brawoliner installation course with the German manufacture KOB which ensures that the installation teams all have the correct training and certification for professionally installing the product.
The company also utilised its latest acquisition, on the project which comprised a new state-of-the-art lateral cutter robotic system which was used to reopen all of the 24 lateral connections along the lined main sewer route. This had to be carried out swiftly to prevent any flow back-up which may have caused flooding in the basements of the 3-storey buildings.
The DALROD team worked tirelessly installing some three (3) Brawoliner sections using both inversion drum and scaffold tower inversion techniques. The three liners installed comprised two relatively short sections of 10 m and 15 m length respectively which used the inversion drum system for insertion. The longest lining of some 68 m length utilised a scaffold tower inversion set-up with the scaffold being some 6.5 m high. This height was necessary to ensure tight fitting of the liner against the host pipe wall whilst balancing the high pressure head of the live flows in the laterals feeding the main sewer being lined. All liners were completed using hot water curing techniques to ensure that the job in Ely was completed with the minimum of disruption to residents and the local surroundings. At one point the crew was accompanied by a security guard as they accessed the rear of a local bank to complete the lining project.
Due to the recent acquisition of a new self-contained mobile lining and welfare suite with beds, canteen etc., the Health & Safety conscious DALROD engineers were able to stay on site and complete the job satisfactorily within 48 hours with works being completed on time and on budget with no disruption or noise pollution to anyone in the vicinity.
The Brawoliner system is offered in the UK and Ireland by Peterborough-based CJ Kelly Associates as the distributor for the liner manufacturer KOB of Germany. The Brawoliner offered several options that would overcome the problems expected to be encountered on site.
For CJ Kelly Associates, John Kelly, senior partner said: “The Brawoliner is a very versatile lining solution that gives wrinkle-free solutions in numerous lining situations. Whilst DALROD used the hot water cure option at Ely the system does offer, both ambient and steam cure options, with the latter using the DocuBox monitoring system where necessary to guarantee that full cure is achieved. The Brawoliner influence in the lining market continues to grow and we are very pleased to be able to offer the benefit of these sorts of experiences to our clients.”