Ross By-Pass TunnelCleanup

Pre-Bid

Project Overview May 2014

Ross Dam

Skagit River

Project Location

This presentation is for general info. Consult the RFP for details.

Ross Dam

Diablo Boat house

City Light Admin Offices

Diablo dam

Diablo Boathouse

Diablo Dam and boat house

Highway 20

To Ross dam

Getting to the work site

Project Location:Ross Hollow Jet Valve House

Hollow Jet Valves

Valve house

Ross Dam

Diablo Lake / Skagit River

Opening to Tunnel

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

Hollow Jet Valves &Valve House

By-pass intakestructure Ross Lake

Diablo Lake

Tunnel and twoBy-pass penstocks

Bypass Penstock Tunnel

Hollow Jet Valves

By-pass penstock

Diablo Lake

Sump Pipe saddles

Typical water Level (1205)

Concrete Tunnel plugTunnel

Valve house Ross Dam

123468 7 510 9

Cross Section of Pipe Supports

Penstocks

Doorway

Tunnel

Concretewall

Not to scale

Tunnel & By-pass penstocks

InsideValve House

Scope of work1. Install temporary weir (vendor) or

permanent weir (SCL)

2. Install rock fall fence (vendor)

3. Remove and treat 1,000,000 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

Lake level can fluctuate 4-5 feet daily.

The lake may have waves.

~8-ft

~5-ft

Higher lake level (elev 1205)

Lower lake level (elev 1199)

1. Install weirWeir• 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

3A. Mobilize

Valve House

SCL Barge

Spill way

Spill way

Ross Dam

Temp rock fence

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.

3B. De-water Tunnel

• Pump out clean water & direct discharge to lake• Pump out dirty* water and treat prior to discharge Approximately

750,000 – 1,000,000 gallons• Water is ~12 – 16-ft deep

*Dirty = > 5 NTU turbidity

3C. Water Treatment on Barge

Settling tank #2

Back flush tank

Settling tank #1

Source tank

ge

ne

rato

r

pumpshack

Sani can

Electro coagulation

Not to scale

Sand filter

Discharge to Diablo Lake

Tunnel

80T Barge

Water Tectonics is the MANDATORY SUB-CONTRACTORMust 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

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

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

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 Mar Apr May Jun Jul Aug Sep Oct

Permits

Procure-ment

Submittal

Tunnel Cleanup

Payment

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%

Incentive for finishing early: $1,000/day