Piers 24 & 25 Sediment Remediation Project

Tacoma, Washington

or… Adventures in Underpier CappingAdventures in Underpier Capping

Rick Moore, Hart Crowser

WEDA Pacific Chapter ConferenceNovember 5, 2009

Acknowledgments• Port of Tacoma• US EPA• US Army Corps of Engineers• Washington State

Department of Ecology• Bergerson Construction• Berger/ABAM

Presentation Overview

Project Setting and Background

Commencement Bay CERCLA ActionsHow Did We Get Here? When Will We Be Done?

Remediation ElementsWhy Do These Projects Always Happen in the Winter?

Lessons LearnedThe Good, the Challenged, and the Long-Term.

Historical Tideflat Filling

Commencement Bay Nearshore/ Tideflats Superfund SiteModified From Port of Tacoma Photo Slide

Sitcum

Hylebos

Thea Foss

Middle

St. Paul

Piers 24 & 25 Project

Site

CERCLA Background• Commencement Bay/Nearshore

Tideflats Superfund Site– Work Began Mid-1980s– 1989 EPA Record of Decision– 20+ Year Cycle to Complete Remediation

• Piers 24 & 25– Part of Mouth of Hylebos Remedial Action – One of the Last CB/NT Remediation Efforts

Site Vicinity and Project Area2006 Aerial

Photo

Source: City of Tacoma

Hylebos Waterway

Blair Waterway

Piers 24 and 25 Project Site

Site Contaminants

• PAH, Metals, and PCB Contamination from Historical Shipyard Waste Disposal

• A Convenient Place to Dump Waste

• A Difficult Place to Clean Up

1940s Shipyard

Piers 24 & 25 Project Site

1946 Aerial Photo

Piers 24 & 25 Project Timeline• 1998 to 2000 Remedial Design

• EPA AOC 2002 and CD 2005

• 2000 to 2007 Revise/Finalize Design

• 10/07 and 2/08 Complete Construction

Remediation Elements• Embankment Capping on 2V:1H Slopes

• Hot Spot Dredging for As Contamination

• Debris Pile Removal

• Hot Spot PCB Removal

A Difficult Place to Work

• Limited Access

• Forest of Pilings

• Steep, Slippery Rock Slopes

Barge-Mounted Placement of Capping Materials

Pier-Mounted Placement of Capping Materials

Sand Cap and Armor Rock Placement

Sand Cap and Armor Rock Placement

Toe Berm Riprap Placement

Sand Cap and Armor Rock

Lead Line Survey Control

Project Area - Post-Capping

Shotcrete Application

Photo Courtesy of the Port of Tacoma

Shotcrete Application

Piers 24 & 25 Project Area

Debris Pile Removal

PCB Hot Spot Removal

PCB Hot Spot Removal

Lessons Learned – The Good• Construction Methods Successful for

Steep Slope Capping

– Sand Cap 400 to 700 CY/Shift

– Crushed Armor Rock 400 to 600 CY/Shift

– Shotcrete 6 to 10 CY/Shift

• Total Construction Cost $4.6M – Within 1% of Engineering Estimate Excluding

Change Orders

The Challenged• PCB Hot Spot and Deeper Debris

Excavation Were Unexpected and Costly

– Difficult Setting to Obtain Good Sampling Data

• 50% Toe Berm Riprap Quantity Over-Run

– Difficult to Estimate Riprap Repose Angle and Settling

And The Long Term…• Piers 24 & 25 Cap Performing as Intended

• Remediation Complete:– Sitcum, Milwaukee, St. Paul, Thea Foss/Wheeler Osgood

Waterways, and ASARCO

• Remediation Pending: OXY/Area 5106

• CB/NT In Post-Construction Monitoring – Portions of the Blair and St. Paul Waterways

Delisted/Deleted from NPL

Thanks to WEDARick MooreHart Crowserrick.moore@hartcrowser.co

m(206) 826-4521

Bill Evans Port of Tacomawevans@portoftacoma.org(253) 593-4563

5106 and “OXY” In-Water Areas

Commencement Bay Waterways