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Ross By-Pass Tunnel Cleanup

Ross By-Pass Tunnel Cleanup. Ross Dam. Pre-Bid Project Overview May 2014. Project Location. This presentation is for general info. Consult the RFP for details. Skagit River. Diablo Boat house. Ross Dam. City Light Admin Offices. Getting to the work site. Diablo Boathouse.

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Ross By-Pass Tunnel Cleanup

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  1. Ross By-Pass Tunnel Cleanup Ross Dam Pre-Bid Project Overview May 2014 Project Location This presentation is for general info. Consult the RFP for details. Skagit River

  2. Diablo Boat house Ross Dam City Light Admin Offices

  3. Getting to the work site Diablo Boathouse Diablo dam Highway 20 To Ross dam Diablo Dam and boat house

  4. Project Location:Ross Hollow Jet Valve House Ross Dam Valve house Hollow Jet Valves Opening to Tunnel Diablo Lake / Skagit River

  5. Problem • Past O&M work (sandblasting) left lead in the sediment in the tunnel. • Can’t pump tunnel dry without discharging lead into Diablo Lake Goal • Remove lead to allow future O&M work to pump tunnel dry when needed for inspections and repairs

  6. Plan view By-pass intake structure Ross Lake Diablo Lake Tunnel and two By-pass penstocks Hollow Jet Valves & Valve House

  7. Bypass Penstock Tunnel Diablo Lake Ross Dam Valve house Typical water Level (1205) 1 3 2 6 4 8 9 7 5 10 Concrete Tunnel plug Hollow Jet Valves By-pass penstock Tunnel Sump Pipe saddles

  8. Cross Section of Pipe Supports Penstocks Concrete wall Tunnel Doorway Not to scale

  9. Inside Valve House Tunnel & By-pass penstocks

  10. Scope of work • Install temporary weir (vendor) or permanent weir (SCL) • Install rock fall fence (vendor) • Remove and treat 1,000,000 gallons of water from tunnel to remove suspended lead (vendor) • Remove 10 – 30 cy sediment (vendor) • Verify & Dispose sediment – could be dangerous waste (SCL)

  11. 1. Opening to tunnel ~8-ft Higher lake level (elev 1205) ~5-ft Lower lake level (elev 1199) Lake level can fluctuate 4-5 feet daily. The lake may have waves.

  12. 1. Install weir Weir • Isolate tunnel from fluctuating lake levels • Protect workers • Keep debris out of tunnel • Contractor can use SCL weir or build their own temporary weir Proposed SCL metal weir (install in June or October depending on Contractor’s preference)

  13. 2. Rock fall Protection (vendor) Temporary fence

  14. 3A. Mobilize Valve House Spill way Temp rock fence SCL Barge Ross Dam Spill way

  15. Vendor Submittals (pre-mobilization) • Health & Safety Plan • Hazardous waste handling plan • Work plan • Contact info • Water Tectonics Electro-coagulation operation manual • Schedule • Spill control plan • Barge loading & operation plan * • Temporary weir * • Rock fall fence • Equipment and materials * Need engineer stamp

  16. Vendor Mobilization • Load water treatment equipment on barge • Provide generator, pumps, worker shack, sani-can, ladders, lights, etc. * Some size restrictions: tunnels, barge load, barge access, etc.

  17. Pump out clean water & direct discharge to lake Pump out dirty* water and treat prior to discharge Approximately 750,000 – 1,000,000 gallons Water is ~12 – 16-ft deep *Dirty = > 5 NTU turbidity 3B. De-water Tunnel

  18. 3C. Water Treatment on Barge Discharge to Diablo Lake pump Tunnel shack Sand filter Back flush tank Settling tank #2 Settling tank #1 Source tank Electro coagulation Sani can generator 80T Barge Not to scale Water Tectonics is the MANDATORY SUB-CONTRACTOR Must use Electro-Coagulation Treatment System

  19. Workers enter all ten chambers Remove sediment (dredge? Pressure wash? Sweep?) Dirty water and sediment pass through treatment Sediment collects in tanks 4. Remove Sediment

  20. 5A. Verification • Clean water is discharged • Batch testing 1 – 3 times • Weekly water discharge samples • Sub-contractor operations • Chambers are clean and lead free • Visual inspection • Water samples

  21. 5B. Waste disposal • Vendor will: • Unload tanks from barge • Transfer sediment to waste containers • Dispose of other debris (trash, sani-can, misc. debris) • SCL will: • Test for dangerous waste • Haul lead-contaminated sediment and sand filter media to proper disposal site

  22. Misc. Vendor tasks • Collect samples & deliver to lab • Provide crew boat to shuttle staff • Provide lodging for crews • Reporting to SCL and Ecology • Site cleanup (non-hazardous materials) • Demobilization

  23. Vendor Selection

  24. Mandatory Pre-bid meeting • At SKAGIT – meet at Newhalem General Store • RSVP • Bring Hard Hat & Lock Out Tag Out locks • Read and be ready to sign SCL LOTO policy • If you don’t bring LOTO locks, you will be left behind at the General Store.

  25. Vendor selection • Requirements • Attend mandatory pre-bid Skagit site visit - Will use Water Tectonics as sub - Can obtain insurance in a timely manner • Pre-qualifications • Worked off barge • Removed underwater sediment • Handled contaminated material

  26. Vendor selection (cont.) • 50% price • 50% approach – submit 4 page document • Work plan • Safety • Environment • Experience FYI: Prevailing wages apply

  27. Tunnel Cleanup Schedule

  28. Activity Submittals and Mobilization Water Treatment System running 5 chambers clean All chambers clean Finish, cleanup, demob Stand by Pay 5% 10% 20% 25% 40% Payment Incentive for finishing early: $1,000/day

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