Case Studies

• Culvert - Rehabilitation of Liawenee Flume, Tasmania

  
  THE LIAWENEE FLUME REHABILITATION PROJECT, TASMANIA

  
  

  The Liawenee Flume is situated high in the mountains north of Hobart, the capital city of Tasmania, an island 180 miles south of Australia.
  
  We were asked by Hydro Tasmania, a short time after we had presented the Ultracoat system, if we were interested in a trial job coating a flume that carried water from the Ouse River onwards via a canal to The Great Lake. The Great Lake services 3 hydro electric power stations, part of the 10,000 gigawatt hour generating capacity of Hydro Tasmania.
  
  The flume needed repairs to the damaged and eroded concrete surface, and the new coating would also need to improve the hydraulic capacity ( flow rate).
  
  The flume was a cast in place concrete ‘U’ section with 10 foot walls and a 12 foot base. The surface was significantly eroded by the water flow and freeze thaw damage. The surface was extremely coarse being an exposed Dolerite aggregate, very sharp and very hard. There was also significant moss growth that would have to be removed.
  
  Interestingly it was in the height of the Tiger snake mating season and the site was surrounded by kangaroos, wallabies, wombats and platypus (we saw them all!)
  
  The Ultracoat system and accessories were shipped from the UK by boat over 12,000 miles to Hobart, Tasmania. After arriving we hired a small truck and a large station wagon, loaded up and set off up the mountain.
  
  The first task was removing the moss, growths and unsound areas from the surface with a high pressure jet washer, and in more difficult areas with a pneumatic scabbler. For the next stage we sprayed the whole area to be coated with a dilute bleach as a mild biocide and thoroughly washed down with copious amounts of water. We followed this with a dilute acid wash to remove carbonates and calcium deposits in the concrete surface, this was again followed by a thorough wash down with water.
  
  Ultracoat is applied at 65 degrees Celsius and due to its thixotropic characteristics Ultracoat can be applied in a single coat up to 8mm thick with no runs or slumping. The standard coating thickness is 6mm.
  
  A movie showing this case study in more detail can be viewed above.

• Manhole - Chemical Factory, Midlands

  Challenge Faced

  The recently installed effluent line infrastructure was suffering from exfiltration and needed to be completely watertight to comply with the latest Environment Agency legislation.

  
  

  About the Project

  Ultracoat pure epoxy was chosen due to its high chemical resistance , ability to adhere to damp substrates and 50 year life expectancy.

  
  

  The work on the 27 chambers had to be done as quickly as possible thus minimising any disruption to production at the site.

  
  

  The Process

  The first phase was to high pressure blast the chambers to SSPC-SP7. Once prepared any infiltration was addressed using our Sealguard II polyurethane grout and our Hyperflex closed cell hydrophobic grout. Once this was achieved a light acid etch was applied to remove sulphates, followed by a mild bleach to kill off any bacteriological growth.

  
  

  The chamber was then sprayed with our plural component patented structural epoxy coating to a thickness of 6mm.

  
  

  • Once completed the chambers were tested to ensure the integrity of the coating.

  • A fifty year warranty was provided for the coating.

  
  

  Summary

  All epoxies are not the same and it is important when choosing a coating that it has been tested against all the chemicals that it is likely to come into contact with. The exfiltration was eliminated, the system is now completely watertight and complies with the latest Environment Agency legislation.

• Large Chamber - Raw Water Sewerage Tank

  
  Large Chamber Raw Water Storage Tank project - Bethlehem, New York                              

  
  

  Challenge faced  

  
  

  The steel tank was built in the 1970’s and was not coated but had been fitted with cathodic protection system which apparently had not worked correctly. The interior wall of the clarifier was uniformly pitted to a depth of 3mm and rust had penetrated to a depth of 6mm. Stratified rust between 6mm and 18mm covered the interior walls. Once cleaned the surface appeared scalloped, the rust in some places penetrating the tank walls.

  The client considered three options; Total replacement of clarifier with stainless steel structure, Painting with NSF approved coating and the installation of cathodic protection or using a NSF approved structural epoxy coating – Ultracoat to restore the integrity of the damaged steel. The client chose the third option as it negated the requirement for cathodic protection  - which had previously failed.

  
  

  About the project

  
  

  The tank measures 4.2m deep by 15m diameter . To ready the interior of the clarifier for coating the rust was removed and the  surface was prepared to SSPC-SP 5 , white metal finish with a 4 mil profile  by abrasive blasting.

  The tank was then washed down and allowed to dry overnight. The flash rusting was removed next morning by blasting with dustless polishing staurite abrasive media.
  
  

  Ultracoat structural epoxy primer was then spray applied to the walls at a thickness of 1mm .
  
  

  An intermediate coat of fibre reinforced Ultracoat structural epoxy was then applied to a thickness of 6mm. ( In tests structural epoxy has a yield strength of 10,000 psi at this thickness – the same as 6mm thick aluminium)

  The top coat a third formulation of the cycloaliphatic epoxy was was applied at a thickness of 2mm.

  
  

  Summary

  
  

  The job was completed within the budgetary and timescale parameters agreed and on completion pull tests indicated adhesion of Ultracoat at over 1000psi and no delamination was observed.
  
  

  In addition to the cost savings achieved the client saved time once the project was complete. Because Ultracoat structural epoxies have no solvents the client could immediately fill the tank once washed down with chlorine.
  
  
  

  
  

• Tunnel Rehabilitation - Miami, Florida

  
  Sewer Project - Miami Dade County, Florida                              

  
  

  Challenge faced  

  This project consisted of deteriorated raw sewer transition vaults made of cast in place concrete and 80m of 1.8m diameter conduits.
  
  

  The chambers and the tunnel had been badly deteriorated by H2S and other sewer gases. In some places the the earth was exposed on the top 1/3 of the tunnel.
  
  

  The tunnel runs parallel and approximately 15 metres away from the Miami river. In storm events the river exerts extreme hydraulic pressure on the system.

  
  

  
  

  About the project

  
  

  Due to the design of the sewer system and the narrow streets over pumping was not an option. CIPP was ruled out due to the configuration of the sewer line and the connections with the chambers. The city was faced with open cut conduit replacement in a heavily congested business district causing major disruption.

  
  

  After review between city engineers and consultants, it was determined that a fast setting structural epoxy – Ultracoat was the natural product for this project.

  
  

  The Ultracoat could be applied during the early hours of the morning at low flow and was cured before the flow returned to maximum levels at 7am.

  
  

  The work area was made safe by purging the system with three separate fans attached to three separate compressors for safety.

  
  

  Due to the porous condition of the substrate the top half of the tunnel was sprayed with Ultracoat Primer resin at 180 ° F. Once the P resin had cured , approximately one hour, the heavily deteriorated areas were filled with Ultracoat structural epoxy fortified with chopped e-glass and crushed ceramic particulate.
  
  

  The e-glass was used to improve ductility and the ceramic particulate was used as a heat sink to improve curing charactaristics.
  
  

  Once the heavily deteriorated areas were repaired the entire surface was coated with 150mls Ultracoat S301 structural epoxy.

  
  

  Summary

  
  

  The project was completed on time and within budget in July 1997 and subsequent annual inspections have confirmed that there is no sign of corrosion, infiltration or delamination of the coating over the last 10 years.

  
  

• Bund Lining - Fuel Bund, Manchester

  

  

   
  
  

  Fuel Bund - Manchester
  
  Challenge Faced

  The mainly brick built fuel bund was built in the 1970s and did not meet the required standard to comply with ISO 14001.
  
  There were numerous areas of the walls in poor repair and the concrete base was in poor condition. The client had the option of rebuilding the bund or lining it. Ultracoat was chosen due to its excellent bonding characteristics, high chemical resistance and the speed of application.

  
  About the Project

  The bund measured 12m x 4m with a 0.7m high wall . To ready the interior of the bund for coating all loose debris and vegetation was removed. The surface of the brickwork was then prepared by abrasive blasting to expose solid substrate. The bund was then degreased followed by acid etching to remove laitance and sulphates from the surface.

  
  Local repairs were undertaken using fast set cement.

  
  The Ultracoat structural epoxy was then spray applied to a thickness of 4mm in a single coat. The epoxy was then “struck off” using a float to force the resin into the mortar joints.
  
  

  Summary

  Weather conditions were severe during the project reaching -7°C at one stage.
   

  However Ultracoat performed to its usual high standard and job was completed within the budgetary and timescale parameters agreed and on completion pull tests indicated adhesion of Ultracoat at over 800psi and all failures occurred within the substrate.
  
  The structure was accepted by the Environment Agency as a waterproof structure.