WET News

Taking pollution out of lining • Keeping water flowing to a cement works was the least of Dalrod's problems on a recent lining project. A no-pollution policy proved particularly challenging. • Liner patch installations over the sand infiltration joints to eliminate the sand wash-in • Brawoliner was used where tight pipeline bends and other challenging circumstances occurred • MC Construction Chemical's Konudur 170 TL-NV resin was used for the majority of the lining work • The new resin does not produce any form of pollution • The blue pigmented resin enables control of the impregna- tion process 1 The rehabilitation had to be completed within a set timeframe 2 No pollution was to be created by the products used on the works 3 Fishery stocks in adjacent lakes had to be protected during the rehabilitation operation 4 Some pipe joints were experiencing running sand infiltration from surrounding soils 5 Inclement weather added to the problems of over pumping S ewer lining specialist Dal- rod Cambridgeshire was involved in a technically challenging project to keep wa- ter flowing to a major cement works in Essex. The site is part of an industrial development in a mined-out area of what is still elsewhere a working quarry, and investigations showed that the pipes that carried away fresh water between two lakes was in need of rehabilitation. However, the fact that the site was industrialised with other operations as well as the cement mixing works, meant that operating conditions for any rehabilitation works would be far from easy. The rehabilitation had to be completed within a set time- frame, with all traffic manage- ment being undertaken by the contractor and there being no pollution created by the prod- ucts used on the works. Before Dalrod was brought to site several other contractors had attempted to survey the pipeline in question but failed due to the level of pipeline deterioration. Having examined the survey results and discussed options with the client, Dalrod was awarded the contract to com- plete the works. Process water The pipeline in need of rehabili- tation runs between two fresh- water lakes and both hold expensive fishery stocks such as carp that had to be protected during the rehabilitation operation. The water supply available from the lakes also provided process water for a nearby cement mixing factory that needed to remain operational through the works Initially, it was thought that the pipeline to be repaired was a 300mm diameter concrete pipe. It was, in fact, a mix of materials both from the original construc- tion and the changing of the pipe material as subsequent repairs were necessary. Also, the survey revealed that various repair jobs had changed the nominal diameter at several points along the route as non- standard pipe had been used to "The successful completion of the work now means that the fresh water supply pipeline is now able to operate very effectively with no sand infiltration or potential for adverse effects on the lakes or their highly prized fish populations. All in all despite the challenging circumstances a job well done" Mike Pollard, Dalrod TreNChLeSS TeChNoLogy complete the repairs. This meant the pipeline varied in diameter to less than 300mm in places. The survey results also high- lighted that the state of the orig- inal pipe was worse than origi- nally expected in that there was significant groundwater infiltra- tion due to the very high ground- water experienced in the vicin- ity of the freshwater lakes. On top of this several of the pipe joints were experiencing run- ning sand infiltration from the surrounding soils, meaning that the pipe foundations were in danger of being washed out, potentially leading to the pipe collapsing. Liner patch To alleviate this problem before lining works could be under- taken in full, Dalrod completed ten liner patch installations over the sand infiltration joints to eliminate the sand wash-in. Once this was solved it was decided that the full pipe lining works could be completed to the project specification using the standard hot water cured resin impregnated felt liner material supplied by CJ Kelly Associates in three separate installations of 46, 110 and 125m lengths. Dal- rod also utilised the standard Brawoliner product where tight pipeline bends and other chal- lenging circumstances occurred. The Brawoliner, also supplied by CJ Kelly, was the easier liner to install for the best results. The difficulty was that the standard resin used with the felt liner did not fully meet the strin- gent non-pollution requirement of the contract. CJ Kelly also rep- resents MC Construction Chemi- cals in the UK – MC has devel- oped a new resin type that cures to a blue colour. The new resin is highly envi- ronmentally-friendly and trials undertaken by Dalrod showed that neither during nor post installation does the new resin produce any form of pollution, nor does any leaching of by- products occur out of liner sub- sequent to lining completion and cure. Mike Pollard, of Dalrod Cam- bridgeshire, comments: "This was the only product that we could find that offered this non- polluting capability and we understand that this is one of the few projects yet undertaken using the new resin. It proved to be just the right product for these circumstances." The MC Construction Chemi- cal resin used for the majority of the lining work was the Konu- dur 170 TL-NV product. Pipe-bends The blue pigmented resin enables control of the impregna- tion process whilst the liner resin combination is flexible enough to negotiate pipe bends. The thermosetting resin has a high chemical and thermal resistance and is easy-to-use at a construction site due to varia- ble application and hardening times. There are also no annulus gap between the host pipe and liner as the installed lining material sits flush to the old pipe wall. More importantly for the pro- ject in hand the resin is certified to be environmentally compati- ble with groundwater. During the course of the lin- ing works, it was not only the level of traffic and the need to keep the industrial sites work- ing that caused Dalrod's crew problems. Initially some water was over-pumped from the upper lake to the lower lake in order to maintain the necessary water supplies to the cement mixing factory. However, very inclement weather added to problems of over pumping during the course of the works as very significant rainfall caused the upper lake to fill to the point of flooding, increasing the need to monitor the lake level and over pump more to ensure that excessive flooding did occur in the sur- rounding area. Pollard says: "The successful completion of the work now means that the fresh water sup- ply pipeline is now able to oper- ate very effectively with no sand infiltration or potential for adverse effects on the lakes or their highly prized fish popula- tions. All in all despite the chal- lenging circumstances a job well done." • rehabilitate a pipeline without interrupting water supply to a cement works • Survey and assess deterioration to the existing pipeline • The scheme must be completed within a set timeframe • There should be no pollution created by the products used 16 WET NEWS APrIL 2015 The non-polluting MC Construction Chemicals Blue resin in the liner was just the right product for this highly environmentally sensitive project The blue pigmented resin enables control of the impregnation process whilst the liner resin combination is flexible enough to negotiate pipe bends

• Cover