Constructing Anacortes’ 36-inch Welded Steel Waterline Replacement Project and its two 1,500-foot-long Horizontal Directional Drills underneath the Skagit River and the Swinomish Channel

Presented byDaniel Williams, P.E.May 1, 2008

Project Overview

• Replacement of 12 miles of 1920’s-vintage 24-inch Pipeline

• $22M in new 36-inch and 24-inch Pipeline Construction

• Two major Waterway Crossings (1,300 feet each) by Horizontal Directional Drill

• Several Bore and Jack crossings of State and County Roadways, wetlands, and Irrigation Ditches

City of Anacortes

Population 16,170

City of Anacortes – Gateway to San Juan Islands

Padilla Bay

City of Anacortes Downtown

City of Anacortes – Ship Building

Oil Refineries (Tesoro and Equilon)

Oak Harbor

Pop. 2,841

Naval Air Station, Whidbey Island

Town of La Conner

Pop. 900

Skagit County Agriculture

History of Existing System

• 1920’s – Original 24-inch Waterline and Raw Water Intake on Skagit River Constructed.• 1950’s – Parallel 36-inch Waterline Constructed to

serve new Oil Refineries and provide redundancy.• 1971 – WTP Constructed to Replace Pressure Filter

Plant and Rainey Well System.• 1995 – Planning for 24-inch Waterline Replacement

Begins• 1999 – 2007: Phased Design and Construction of

new 36-inch Pipeline.

Customers of Anacortes Water Supply

• Equilon Oil Refinery (Texaco) – 7 MGD (38%)• Tesoro Oil Refinery (Shell) – 5 MGD (28%)• Oak Harbor / Naval Air Station – 2.3 MGD (13%)• City of Anacortes – 1.7 MGD (10%) • Skagit County PUD – 1.6 MGD (9%)• Town of La Conner – 0.4 MGD (2%)• Swinomish Tribal Community – 0.07 MGD (0.4%)

Planning and Design Team

• City of Anacortes• MWH – Design and Construction Management• Landau Associates – Geotechnical Engineer• Reid Middleton – Surveying• LBS – Surveying• Pharos Corporation – Right-of-way Acquisition• Staheli Trenchless – Trenchless Design• Evergreen Aquatic Resources – Environmental and

Permitting

Agency Approvals

• State Department of Health (DOH)• State Department of Transportation (WSDOT)• State Department of Ecology• U.S. Army Corps of Engineers• Skagit County• Diking Districts

Construction Contractors

• 2001 – Segment 3A – R.L. Alia• 2001 – Segment 3B – Tri State Construction• 2002 – Segment 1 – Robison Construction Co.• 2002 – Segment 2 – Robison Construction Co.• 2004 – Segment 4 – James W. Fowler• 2007 – Segment 5 & 6 – Tri State Construction• Welded Steel Pipe Supplier – Northwest Pipe• Ductile Iron Pipe Supplier – American CI Pipe Co.

Construction Costs

• Segment 3A – 9,500 LF 36” WSP – $2.5M• Segment 3B – 2,940 LF 36” WSP – $1.0M • Segment 1 – 14,400 LF 36” WSP – $3.4M • Segment 2 – 1,300 LF HDD – $1.0M • Segment 4 – 5,200 LF 24” DI – $2.8M• Segment 5 – 17,000 LF 36” WSP (Pipe) – $2.5M• Segment 5/6 – 17,000 LF 36” WSP (Install) – $9.2M

Total Construction Cost = $22.4M

Design Criteria -- Hydraulics

• Design Flow Rate – 27.5 MGD• Velocity – 6 fps• Typical Operating Pressure – 120 psi to 180 psi• Maximum Design Working Pressure – 250 psi• Maximum Transient Design Pressure – 332 psi

Design Criteria -- Pipe

• Steel Pipe – AWWA C200, mortar-lined, tape coated, double-welded lap joints

• Steel Pipe – Minimum D/t Ratio – 240• Ductile Iron Pipe – AWWA C151, mortar-lined,

asphaltic coating, restrained joints• Typical Modulus of Soil Reaction (E’) = 700• Very High Groundwater in Winter• Liquifaction possible in some reaches during seismic

events.

Trenchless Methods for River Crossings

• Pipe Bridge (Swinomish Channel Crossing)• Microtunnel• Horizontal Directional Drill (HDD)

HDD was selected based on cost savings, suitable soils, and room to lay out pipe.

Other Issues

• Twin Bridges Marina Repairs at low, low tide• Restraint of Joints on Existing 36-inch Pipeline

constructed with Sleeve-type Coupling Joints• Agricultural soil preservation/restoration• WSU Agricultural Station and Skagitonians for

Agricultural Preservation.

Other Issues Continued

• Army COE and Diking Districts’ Approval for Skagit River Crossing (entry and exit points were placed adequately back from Dikes, plus grout plugs).

• WTP Tie-in and HDD geometry.• Easements, Landowner Notification, and

Property Restoration

Swinomish Channel Crossing – Overview

• Length – 1,300 feet• Depth Below Channel Bottom – 36 feet• Maximum Depth Below Ground Elevation – 60 feet• Pipe Diameter – 36-inch Welded Steel, Polyurethane Lined and Coated

Swinomish Channel Crossing – Overview

• Length – 1,300 feet• Depth Below Channel Bottom – 36 feet• Maximum Depth Below Ground Elevation – 60 feet• Pipe Diameter – 36-inch Welded Steel, Polyurethane Lined and Coated

Swinomish Channel Crossing –Construction Sequence

• Drill 12-inch Diameter Pilot Hole• Pull 24-inch Ream back through Pilot Hole• Push 50-inch Ream through 24-inch Hole• Pull 50-inch Swab back through 50-inch Hole (to

Verify that Hole is Clean)• Pull back 36-inch Diameter Pipe

Swinomish Channel Crossing – Drill 12-inch Diameter Pilot Hole

• Start Pilot Hole: 8/7/02• Finish Pilot Hole: 8/12/02• Advance Rate: 2 to 3 feet/min.

Swinomish Channel Crossing – Push 24-inch Ream through Pilot Hole

• Started Ream: 8/15/02• Finished Ream: 8/17/02• Advance Rate: 1 foot per min.

Swinomish Channel Crossing – Push 50-inch Diameter Ream through 24-inch Hole

• Start 50-inch Ream: 8/17/02• Finish 50-inch Ream: 8/19/02• Advance Rate: 30 feet per hour• Worked 24 hours per day to compete 50-inch Ream

Swinomish Channel – Pull Back 36-inch Pipe

• Start Pull Back: 7:00 a.m.• Finish Pull Back: Midnight• Pull Back Rate: 30-feet every 10 minutes• Pulling Force at Drilling Machine was 170,000 to

180,000 pounds

Swinomish Crossing – Misc Photos

Skagit River HDD Crossing – Installed 2007

• Length: 1,540 feet• Depth Below River: 45 feet• Depth below Grade: 75 feet• Pipe: 36-inch welded steel

36-inch Steel Pipe Prior to Pull

Skagit River HDD -- Timeline

• Set up Drill Machine – Aug 27th

• 8-inch Pilot Hole – Sept 3rd

• 24-inch Ream back through Pilot Hole – Sept 7th

• 44-inch Ream back – Sept 14th• 54-inch Ream back – Sept 18th• Pulled 36-inch pipe beginning 10:00 a.m. and

ending at 5:00 p.m., September 22nd.Note: Pulling force reached 300,000 lbs

36-inch Steel Pipe prior to Pull

Ready to Pullback 36-inch Pipe

Cranes Support 36-inch Pipe during Pull

Cranes Support 36-inch Pipe during Pull

WTP Tie-in – 36-inch Fittings and Couplings

Dewatering Well Construction

Pipeline Installation aided by Dewatering

Dewatering Wells and Vacuum Header Pipe

Hot Tap tie-in to 24-inch Ductile Iron Pipe

36-inch Steel Pipe prior to Installation

Pipe resting on Sand Supports

Bell and Spigot Lap Joint prior to Welding

36-inch Pipe Installation

36-inch Pipe Strung out Prior to Installation

Future Work on Existing (old) 36-inch Steel Pipe

• City is evaluating burying portions of above-ground pipe due to corrosion and aesthetics

Existing Above Ground Pipe – on Piles

Difficult to Keep Pipe from Corroding at Saddles

Existing Steel Pipe next to Padilla Bay

For Additional Information:

• Gordon Bruchner, Anacortes• Brandt Barnes, MWH• Bob Clumpner, Anacortes

Also, Greg Harris, MWH, and Linda Stiegler, MWH