Glenlatterach – Restoration of water supply to a remote community CASE STUDY-GLENLATTERACH Glenlatterach is located to the west of the A941, about 10 km south of Elgin, and to the north of the Cairngorms National Park. It is a wild, sparsely populated area dominated by open moorland, woodland and tributaries of the River Lossie. Prolonged and heavy rainfall has caused the river to swell and washed away the existing concrete asbestos water main, housed in a protective ductile iron casing. This was the only source of water for about 5,000 properties. A cluster of temporary 25mm and 32mm pipes had been strung across the river as a temporary measure. There was a real fear the pipes would freeze as winter set in. Scottish Water appointed Nicol of Skene to install a replacement 180mm polyethylene main using directional drilling techniques. Other companies had declined to tender due to the project’s many complexities, The outline scope of works was to drill a borehole through rock, down a ravine with a 58m fall, and under the River Lossie, The exit point for the borehole on the far side of the river was in an SSSI: a site of specific scientific interest. What could possibly go wrong?! The first challenge was logistics. The drilling compound was on open ground at the top of the ravine (see below): The exit point was 1.5 miles from the nearest road and, due to access constraints imposed by environmental concerns, could only be accessed by a small tracked digger and a six-wheeled off-road buggy. It was a 7 mile round trip from the drilling compound to the access route to the exit point. Nicol used a drone to survey the area both before and during the project. A photo from the drone clearly shows the drilling compound (right), temporary pipework (centre) and exit point (left). The moorland and woodland landscape where the directional drilling project took place The drilling plan developed by Gordon Ellis, Nicol’s Head of Directional Drilling, is shown below. It shows how steep the drill path is before it levels out below the river. Nicol used a Ditch Witch JT100 all-terrain rig equipped with tricone TCI (Tungsten Carbide Insert) drilling heads and TCI reamers. The borehole was over-reamed to 400mm to flush out sand deposits. Bentonite was used to lubricate the drilling process and to seal the hole prior to insertion of the pipe. Directional drilling compound and entry point at Glenlatterach Directional drilling exit point at Glenlatterach Drone image of the directional drilling compound, temporary pipework and exit pit. Nicol’s directional drilling plan for Glenlatterach This sounds far simpler in theory than it was in practice! The River Lossie feeds several local distilleries so it was critical there was no contamination. The steep fall of the ravine meant the head pressure of the bentonite in the borehole was extremely high and retrieval of the bentonite could not be achieved using standard pumping techniques, a suction tanker, or through the use of Nicol’s suction excavator. The exit point of the borehole was in an SSSI which posed obvious issues with regards to the potential environmental impact of storing or disposing of the bentonite in that location. The severity of the constraints can be seen by the fact that Scottish Water asked Nicol to obtain quotes for removal of the bentonite via helicopter. Working closely with Scottish Water, Scottish Natural Heritage, and Moray Estate all available options were reviewed. Bentonite is a natural material and the final decision was to ‘bury’ it in a pit close to the exit point. The first step was to safely remove ferns and bracken. The topsoil was carefully stripped and stored to one side in order to retain the spores and seedlings that would re-establish the natural vegetation after the project was completed. The surplus bentonite was then mixed with the subsoil in the trench to increase its viscosity and minimise the risk of leaching. Delays in obtaining permissions from land owners meant that the project did not start on site until November. The project took less than a month to complete, and all properties were reconnected to a permanent mains supply well before Christmas. KEY BENEFITS Innovation The principal innovation came in designing the solution for the disposal of the bentonite in an SSSI. As on many directional drilling projects, it was the secondary elements that turned the project from good to outstanding. The final design is described in detail in the body of the case study: Working closely with Scottish Water, Scottish Natural Heritage, and Moray Estate, all available options were reviewed. Bentonite is a natural material and the final decision was to ‘bury’ it in a pit close to the exit point. The first step was to safely remove ferns and bracken. The topsoil was carefully stripped and stored to one side in order to retain the spores and seedlings that would re-establish the natural vegetation after the project was completed. The surplus bentonite was then mixed with the subsoil in the trench to increase its viscosity and minimise the risk of leaching. Environment Nicol is very proud of its roots in North East Scotland and the natural beauty of the area. On this project, focus on protecting the environment was paramount both with regards to the River Lossie and the SSSI at the exit point. Use of the tracked digger and the six-wheel all-terrain buggy minimised the environmental impact of reaching the borehole exit point and also used less fuel than alternative options. Once completed, the landowner stated that he could not believe how tidy the area was and how little impact it had had on the area. The natural vegetation should re-establish itself over Spring and Summer 2018 and by 2019 there will be little, if any evidence, of the drilling project. Community impact and customer care On this project, time was of the essence. The ‘community impact’ of failing to meet the deadline would have left Scottish Water with no alternative other than to tanker water into the 5,000 properties serviced by the previous water main. The environmental and economic impact of large tankers on the narrow, serpentine roads would have been immense. Nicol built up good relations with the local population and, importantly, with landowners impacted by the project. At the end of the project, Nicol repaired potholes and rehung gates to ensure the site and access roads were in better condition than before the project has started. Project management The key aspect of project management was ensuring all landowners were kept informed, and that all plans were approved by Scottish Natural Heritage (SNH). SNH took a pragmatic approach to the seriousness of the water supply challenge and were proactive in developing and approving plans. Legislative compliance The project complied with all relevant construction legislation. In particular, Nicol had to ensure compliance with stringent SEPA (Scottish Environmental Protection Agency) environmental criteria due to working in an SSSI. The Nicol difference The complexity of the challenges on this project meant other contractors declined to tender. Nicol has a reputation for ‘getting the job done’. Nicol believes it is important for directional drilling contractors not to shy away from more complex projects otherwise the potential that the techniques can offer clients may be undermined. Nicol’s investment in all-terrain technology, in this case the Ditch Witch JT100, meant it had equipment that was powerful enough to complete the borehole. Nicol worked closely with all other parties to design and implement a solution that worked within the physical, environmental and time constraints.