Water Tank Rehabilitation For A Small Community

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Presented at the Arizona Water Association (AZWA) Conference, Glendale, May 2010

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Water Tank Rehabilitation For A Small Community

  1. 1. Water Tank Rehabilitation for a Small Community Presented By: Ajay Kashi Gannett Fleming Inc.
  2. 2. Water Tank Rehabilitation for a Small Community TOWN OF BOWIE LOCATION MAP
  3. 3. Water Tank Rehabilitation for a Small Community <ul><li>PRESENTATION OVERVIEW </li></ul><ul><ul><li>Introduction </li></ul></ul><ul><ul><li>Objective </li></ul></ul><ul><ul><li>Project Funding </li></ul></ul><ul><ul><li>Project Execution </li></ul></ul><ul><ul><li>Lessons Learned </li></ul></ul>
  4. 4. Water Tank Rehabilitation for a Small Community <ul><li>INTRODUCTION </li></ul><ul><ul><li>History & Background </li></ul></ul><ul><ul><ul><li>Approximately 70 years old </li></ul></ul></ul><ul><ul><ul><li>Privately owned until 1985 </li></ul></ul></ul><ul><ul><ul><li>Currently Maintained & Operated by BWID </li></ul></ul></ul><ul><ul><li>Existing Water System </li></ul></ul><ul><ul><ul><li>Two (2) Groundwater Wells </li></ul></ul></ul><ul><ul><ul><li>One (1) 150,000 Gallon Storage Tank </li></ul></ul></ul><ul><ul><ul><li>Two (2) Hydro-pneumatic Tanks </li></ul></ul></ul><ul><ul><ul><li>2”, 4” and 6” Waterlines </li></ul></ul></ul>
  5. 5. Water Tank Rehabilitation for a Small Community <ul><li>CONDITION OF THE TANK </li></ul><ul><ul><li>Exterior </li></ul></ul>
  6. 6. Water Tank Rehabilitation for a Small Community <ul><li>CONDITION OF THE TANK </li></ul><ul><ul><li>Interior </li></ul></ul>
  7. 7. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT OBJECTIVE </li></ul><ul><ul><li>Restore Health and Safety </li></ul></ul><ul><ul><ul><li>Replace or Rehabilitate the Tank </li></ul></ul></ul><ul><ul><ul><li>Eliminate Rust and Deterioration </li></ul></ul></ul><ul><ul><ul><li>Safe Environment for the Operators </li></ul></ul></ul>
  8. 8. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT FUNDING </li></ul><ul><ul><li>Completely Funded by USDA-RD (United States Department of Agriculture - Rural Development) </li></ul></ul><ul><ul><li>Gannett Fleming Inc, was selected as Consulting Engineers to prepare a Preliminary Engineering Report (PER) </li></ul></ul>
  9. 9. Water Tank Rehabilitation for a Small Community <ul><ul><li>PER (Comprehensive Report) </li></ul></ul><ul><ul><ul><li>Thorough Site Investigation </li></ul></ul></ul><ul><ul><ul><li>Discussions with the BWID to identify Operations and Maintenance issues </li></ul></ul></ul><ul><ul><ul><li>Financial Information </li></ul></ul></ul><ul><ul><ul><li>Alternative Improvements Considered </li></ul></ul></ul><ul><ul><ul><li>Engineer’s Estimate of the Costs </li></ul></ul></ul><ul><ul><ul><li>Alternative Improvement Recommendation </li></ul></ul></ul><ul><ul><ul><li>Rural Development Approved Funding for Tank Rehabilitation </li></ul></ul></ul>
  10. 10. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Construction Phase Services </li></ul></ul><ul><ul><ul><li>Gannett Fleming provided </li></ul></ul></ul><ul><ul><ul><li>Project Representative </li></ul></ul></ul><ul><ul><ul><li>Services during Rehabilitation </li></ul></ul></ul><ul><ul><li>Bypass Piping Modifications </li></ul></ul>
  11. 11. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Guardrail Installation according to OSHA Standards </li></ul></ul>
  12. 12. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Tank Interior Cleaning </li></ul></ul>
  13. 13. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Interior after Blasting </li></ul></ul>
  14. 14. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Interior Inspection and Tank Floor Cost Evaluation </li></ul></ul>
  15. 15. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Tank Floor Installation </li></ul></ul>
  16. 16. Water Tank Rehabilitation for a Small Community <ul><li>VACUUM TEST </li></ul><ul><ul><li>Welded Joints were tested for </li></ul></ul><ul><ul><li>air-tightness </li></ul></ul>
  17. 17. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Interior Inspection Prior to Coating </li></ul></ul>
  18. 18. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Epoxy based NSF 61 Approved </li></ul></ul><ul><ul><li>Interior Coating </li></ul></ul><ul><ul><ul><li>Three Coat System </li></ul></ul></ul><ul><ul><ul><ul><li>Prime Coat (4 mils) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Intermediate Coat (5 mils) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Finish Coat (5 mils) </li></ul></ul></ul></ul><ul><ul><li>Welds, seams and irregular </li></ul></ul><ul><ul><li>surfaces were coated with brush </li></ul></ul><ul><ul><li>Smooth surfaces were coated </li></ul></ul><ul><ul><li>with rollers </li></ul></ul>
  19. 19. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>NSF 61 Approved Interior Coating </li></ul></ul><ul><ul><ul><li>Sealant (Polyurethane Elastomeric Adhesive) for Roof Plate Lap Joints </li></ul></ul></ul>
  20. 20. Water Tank Rehabilitation for a Small Community <ul><li>Tests for Interior Coating System </li></ul><ul><ul><li>Dry Film Thickness Test </li></ul></ul><ul><ul><li>Holiday Test (Low Voltage Wet Sponge Test) </li></ul></ul>
  21. 21. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Exterior Coating (Epoxy Based) </li></ul></ul><ul><ul><ul><li>Pressure Washed According </li></ul></ul></ul><ul><ul><ul><li>to SSPC Standards </li></ul></ul></ul><ul><ul><ul><li>Two Coat System </li></ul></ul></ul><ul><ul><ul><li>Prime and Finish Coat </li></ul></ul></ul><ul><ul><ul><li>Total System Thickness </li></ul></ul></ul><ul><ul><ul><li>of 5 – 8 mils (DFT) </li></ul></ul></ul>
  22. 22. Water Tank Rehabilitation for a Small Community <ul><li>PROJECT EXECUTION </li></ul><ul><ul><li>Disinfection </li></ul></ul><ul><ul><ul><li>AWWA C652 Stds and ADEQ Bulletin No. 8 </li></ul></ul></ul><ul><ul><ul><li>Interior Pressure Washed prior to Disinfection </li></ul></ul></ul><ul><ul><ul><li>200 mg/l Available Chlorine was Sprayed on the Interior Surface </li></ul></ul></ul><ul><ul><ul><li>Water allowed inside after 30 minutes of Disinfectant Retention Time </li></ul></ul></ul><ul><ul><li>Testing </li></ul></ul><ul><ul><ul><li>BAC-T for Coliform Organisms </li></ul></ul></ul>
  23. 23. Water Tank Rehabilitation for a Small Community <ul><li>LESSONS LEARNED </li></ul><ul><ul><li>Thorough Tank Inspection is Critical Prior to start of the Project </li></ul></ul><ul><ul><li>Thorough Interior Surface Inspection after Blasting is Essential </li></ul></ul><ul><ul><li>Confined Space Entry </li></ul></ul><ul><ul><ul><li>Entry Permit and Procedures were required for the Contractor and Site Inspectors according to OSHA </li></ul></ul></ul>
  24. 24. Water Tank Rehabilitation for a Small Community <ul><li>ACKNOWLEDGEMENT </li></ul><ul><ul><li>USDA Rural Development </li></ul></ul><ul><ul><li>Bowie Water Improvement District, Town of Bowie </li></ul></ul>
  25. 25. Water Tank Rehabilitation for a Small Community Questions ?
  26. 26. <ul><li>SAND BLASTING </li></ul><ul><li>Dry Abrasive Blasting </li></ul><ul><li>The abrasive media was Silica Sand coated with Resins to prevent creation of dust during blasting process. </li></ul><ul><li>Abrasive Media Particle size range between 10 micrometer to 150 micrometers. </li></ul>Vessel containing abrasive media Power supply & Air-Compressor From the Vessel media is pressurized through a pipe into a hand held nozzle in the end
  27. 27. <ul><li>HOLIDAY TEST INFORMATION </li></ul><ul><li>For Holiday Tests, the Detector is set at 700 Micro-Amps (mA) to set off an audible indicator. </li></ul><ul><li>Low Voltage Holiday Tests are conducted for metal surfaces which have coatings of 20 mils or less. </li></ul><ul><li>High Voltage Holiday Tests are conducted for metal surfaces which have coatings of 20 mils or greater. </li></ul>
  28. 28. <ul><li>DISINFECTION </li></ul><ul><li>Overflow piping need not be disinfected according to AWWA C652 standards for “Disinfection of Water Facilities.” </li></ul><ul><li>Required Chlorine Residual in water according to AWWA C652 Standards is 2 mg/l. </li></ul>
  29. 29. <ul><li>USDA-RD FUNDING CRITERIA FOR BOWIE </li></ul><ul><li>Bowie is a very poor rural community </li></ul><ul><li>The funding criteria for a Rural Community is based on its Median Household Income (MHI). </li></ul><ul><li>If the MHI for a Rural Community is LESS THAN 50% of the MHI for the State, that Rural Community is qualified for a 100% Grant by the USDA-RD. </li></ul><ul><li>MHI data can be obtained from the Department of Labor Statistics. </li></ul>
  30. 30. <ul><li>ANOTHER OPTION FOR FIXING THE TANK FLOOR </li></ul><ul><li>Apply 50 mils of a Solventless Elastomeric Polyurethane immediately after the Prime Coat on the Interior Surface of the Tank including Roof and Rafters. </li></ul><ul><li>Estimated Cost for Applying the Coat was $30K </li></ul>

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