Ross ByPass Tunnel Cleanup Ross Dam PreBid Project
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 Diablo dam Hi gh w ay 20 To Ross dam Diablo Dam and boat house
Project Location: Ross Hollow Jet Valve House Valve house Hollow Jet Valves Opening to Tunnel Diablo Lake / Skagit River Ross Dam
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
Plan view By-pass intake structure Ross Lake Diablo Lake Tunnel and two By-pass penstocks Hollow Jet Valves & Valve House
Bypass Penstock Tunnel Diablo Lake Ross Dam Valve house Typical water Level (1205) 10 Hollow Jet Valves 9 8 Sump 7 6 By-pass penstock 5 4 Pipe saddles 3 Tunnel 2 1 Concrete Tunnel plug
Cross Section of Pipe Supports Penstocks Concrete wall Tunnel Doorway Not to scale
Inside Valve House Tunnel & By-pass penstocks
Scope of work 1. Install temporary weir (vendor) or permanent weir (SCL) 2. Install rock fall fence (vendor) 3. Remove and treat 1, 000 gallons of water from tunnel to remove suspended lead (vendor) 4. Remove 10 – 30 cy sediment (vendor) 5. Verify & Dispose sediment – could be dangerous waste (SCL)
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.
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)
2. Rock fall Protection (vendor) Temporary fence
3 A. Mobilize Valve House Spill way Temp rock fence SCL Barge Ross Dam Spill way
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
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.
3 B. De-water Tunnel • Pump out clean water & direct discharge to lake • Pump out dirty* water and treat prior to discharge Approximately 750, 000 – 1, 000 gallons • Water is ~12 – 16 -ft deep *Dirty = > 5 NTU turbidity
3 C. Water Treatment on Barge Discharge to Diablo Lake Tunnel Settling tank #2 Settling tank #1 Electro coagulation Sani can pump Back flush tank Source tank generator Sand filter shack 80 T Barge Not to scale Water Tectonics is the MANDATORY SUB-CONTRACTOR Must use Electro-Coagulation Treatment System
4. Remove Sediment • Workers enter all ten chambers • Remove sediment (dredge? Pressure wash? Sweep? ) • Dirty water and sediment pass through treatment • Sediment collects in tanks
5 A. 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
5 B. 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
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
Vendor Selection
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.
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
Vendor selection (cont. ) • 50% price • 50% approach – submit 4 page document – – Work plan Safety Environment Experience FYI: Prevailing wages apply
Tunnel Cleanup Schedule Feb Permits Procurement Submittal Tunnel Cleanup Mar Apr May Jun Jul Aug Sep Oct
Payment Activity • Submittals and Mobilization • Water Treatment System running • 5 chambers clean • All chambers clean • Finish, cleanup, demob • Stand by Incentive for finishing early: $1, 000/day Pay 5% 10% 25% 40%
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