River Mile 13.5 Sediment Isolation Cap Construction Completion Report

River Mile 13.5 Lower Willamette River Portland, Oregon

April 29, 2016

Prepared for: Portland General Electric Company 121 SW Salmon Street Portland, Oregon 97204

Prepared by:

1501 4th Ave, Suite 1400 Seattle, Washington 98101

Job No. 60439278

CONTENTS

1.0 Introduction ...... 1-1 1.1 Site Conditions ...... 1-1 1.2 Background Information ...... 1-1 1.3 Approvals and Permits ...... 1-2 1.4 Project Team and Roles and Responsibilities ...... 1-3 2.0 Remedial Design...... 2-1 2.1 Debris Removal ...... 2-1 2.2 Isolation Cap...... 2-1 2.3 Armor Stone ...... 2-2 3.0 Pre-Construction Activities ...... 3-1 3.1 Health and Safety ...... 3-1 3.2 Baseline Environmental Monitoring and Engineering Controls ...... 3-1 3.2.1 Baseline Turbidity Monitoring ...... 3-1 3.2.2 Baseline Noise Monitoring ...... 3-2 3.2.3 Baseline Dust Monitoring ...... 3-2 3.2.4 Floating Debris Boom ...... 3-2 3.3 Equipment Mobilization ...... 3-2 3.4 Debris Removal, Sampling, and Disposal ...... 3-2 3.5 Post Debris Removal Bathymetric Survey ...... 3-3 4.0 Construction Activities ...... 4-1 4.1 Fill Material Verification ...... 4-1 4.1.1 Isolation Cap Sand Layer Material ...... 4-1 4.1.2 Armor Stone Material ...... 4-1 4.2 Isolation Sand Layer Construction ...... 4-2 4.2.1 Placement Methods ...... 4-2 4.2.2 Placement Sequence ...... 4-2 4.2.3 Final Confirmation Bathymetric Survey...... 4-3 4.2.4 Deviations from Remedial Design ...... 4-4 4.3 Armor Layer Construction ...... 4-5 4.3.1 Placement Methods ...... 4-5 4.3.2 Placement Sequence ...... 4-5 4.3.3 Final Confirmation Bathymetric Survey...... 4-6 4.3.4 Deviations from Remedial Design ...... 4-6 4.4 Final Diver Inspection ...... 4-8 4.5 Demobilization ...... 4-8 4.6 Environmental Monitoring ...... 4-8

i CONTENTS

4.6.1 Turbidity Monitoring ...... 4-8 4.6.2 Noise Monitoring ...... 4-9 4.6.3 Dust Monitoring ...... 4-9 4.7 Archaeological Observations ...... 4-10 4.8 Health and Safety ...... 4-10 4.9 Best Management Practices ...... 4-10 4.10 Sustainable Remedial Practices ...... 4-10 4.11 Utilities and Easements ...... 4-11 4.12 Survey Control ...... 4-11 5.0 Long-Term Monitoring ...... 5-1 6.0 Certification Statement ...... 6-1 7.0 References ...... 7-1

ii CONTENTS

TABLES Table 1-1 RM 13.5 Feasibility Study SWAC Analysis Table 1-2 RM 13.5 Remedial Action Objectives and Remedial Goals Table 4-1 Sediment Isolation Cap Chronology Table 4-2 Fill Material Volume Summary Table 4-3 Environmental Monitoring Summary

FIGURES Figure 1-1 Site Location Map Figure 2-1 Proposed Sediment Isolation Cap Extent Figure 3-1 Environmental Monitoring Locations Figure 3-2 Post Debris Removal Elevation (Pre-cap) Figure 4-1 Placement Grid Cell Layout Figure 4-2 Isolation Sand Layer Placement Pictures Figure 4-3 Final Isolation Sand Layer Thickness Figure 4-4 Final As-Built Sand Isolation Layer Slope Figure 4-5 Armor Layer Placement Pictures Figure 4-6 Final Armor Layer Thickness Figure 4-7 Final As-Built Armor Layer Slope Figure 4-8 Final Bathymetric Contours (Post-capping) and Shoreline Habitat Shelf

APPENDICES Appendix A Permits Appendix B Daily Field Reports Appendix C As-Built Drawings Appendix D Turbidity Monitoring Data Appendix E Noise Monitoring Data Appendix F Dust Monitoring Data Appendix G Debris Disposal Data Appendix H Post Debris Removal Survey Data Appendix I DEQ Correspondence Appendix J Armor Stone Gradation Results Appendix K Response to DEQ’s Comments on the RM 13.5 Installed Armor Stone Size Appendix L Sediment Core Information Appendix M Final Sand Layer Survey Data Appendix N Final Armor Layer Survey Data Appendix O Wash Water Analytical and Disposal Appendix P HME Letter of Certification

iii ACRONYMS AND ABBREVIATIONS

BDS Bureau of Development Services BES Bureau of Environmental Services BMP best management practice CCR Construction Completion Report City City of Portland COPC contaminant of potential concern COPD City of Portland Datum Corps U.S. Army Corps of Engineers cy cubic yard(s) dB decibel(s) DDD dichlorodiphenyldichloro-ethane DDE dichlorodiphenyldichloro-ethylene DDT dichlorodiphenyltrichloro-ethane DDx sum of DDD, DDE, and DDT DEQ [Oregon] Department of Environmental Quality DFR daily field report DSL [Oregon] Department of State Lands ESA Endangered Species Act FS Feasibility Study ft2 square foot/feet FWS [U.S.] Fish and Wildlife Service HASP Health and Safety Plan HME HME Construction, Inc. IDP Inadvertent Discovery Plan mg/m3 milligrams per cubic meter MUBC mean upriver background concentration NAD North American Datum NAVD North American Vertical Datum NHPA National Historic Preservation Act NMFS National Marine Fisheries Service NOAA National Oceanic and Atmospheric Administration NRC Northern Resource Consulting, Inc. NTU Nephelometric turbidity unit OAR Oregon Administrative Rules OLW ordinary low water OMSI Oregon Museum of Science and Industry ORS Oregon Revised Statutes PCBs polychlorinated biphenyls PGE Portland General Electric Company

iv ACRONYMS AND ABBREVIATIONS

QC quality control RA Remedial Action RAO Remedial Action Objective RD Remedial Design RG Remedial Goal RI Remedial Investigation RM river mile ROD Record of Decision RTK-GPS real-time kinematic global positioning system SHPO State Historic Preservation Office SPCS State Plane Coordinate System SWAC surface weighted average concentration TEQ total equivalency factor

v SECTIONONE Introduction

1.0 INTRODUCTION AECOM has prepared this Construction Completion Report (CCR), on behalf of Portland General Electric Company (PGE), to document completion of the Remedial Action (RA), a sediment isolation cap to contain impacted river sediments in a discrete area at river mile (RM) 13.5 in the lower Willamette River (river). This sediment isolation cap (cap) was designed to prevent exposure to human and ecological receptors from surface sediment and to reduce the mobility of contaminants in the underlying sediment. The construction was completed in accordance with the Remedial Design (RD), as documented in the Final Remedial Design Report, River Mile 13.5 Sediment Study Area (AECOM 2015) (RD Report). The RD Report, conditionally approved (with required agreed upon revisions) by the Oregon Department of Environmental Quality (DEQ) on September 9, 2015, was completed in accordance with the DEQ’s Record of Decision (ROD) and the DEQ No. LQVC-NWR-12-07 Order on Consent issued July 16, 2012 (DEQ 2015; DEQ 2012).

1.1 Site Conditions The RM 13.5 Study Area encompasses 94,852 square feet (ft2) (2.18 acres) on the east side of the lower Willamette River, in the Downtown Reach Area of Portland, Oregon (Figure 1-1). The majority of the Study Area is located below the ordinary low water (OLW) line and is owned by the Oregon Department of State Lands (DSL). The upland properties above the OLW include tax lots 200 and 203, owned by the Oregon Museum of Science and Industry (OMSI); and tax lot 202, owned by TriMet. The upland area is primarily covered with asphalt, buildings, or landscaping. Immediately downstream of the Study Area are the USS Blueback submarine exhibit and the Marquam Bridge, and upstream is the Tilikum Crossing. Water depths generally range from 0 to 40 feet, and substrate is generally characterized as large riprap and cobbles along the shoreline with predominantly silts with sand and gravel in the river channel. The Eastbank Esplanade, a pedestrian walking path, is located along the top of the riverbank through this area. The eastern bank adjacent to the Study Area is steeply graded and covered in riprap and vegetation, with no direct public access. The riprap shoreline grades steeply to the river bottom, which consists of fine granular sand with some gravel and woodchips in the sediment in the vicinity of the Study Area. Stormwater runoff from the upland properties is controlled and ground infiltrates or is discharged to either the City of Portland (City) or the TriMet stormwater systems. Utilities and associated easements are present within the southern portion of the Study Area, including two NW Natural gas lines, one active and one inactive; a City water line; an active City stormwater outfall, identified as ABU956; and an active TriMet outfall, identified as AQK79. The Tilikum Crossing Bridge is located overhead across the southern portion of the Study Area.

1.2 Background Information Historically, the RM 13.5 Study Area bordered industrial upland properties with water-dependent and shoreline uses. The former Station L southern yard was an adjacent upland property owned by PGE, where electrical equipment was stored and operated from the mid-1930s to the 1970s. Historical spills in the vicinity of the Study Area may have occurred during the industrial use of these upland areas and associated in-water uses, which included boat building and log rafting (from approximately 1890 until the mid-1950s) and unloading fuel from a historical docking facility (from approximately 1957 to 1994).

1-1 SECTIONONE Introduction

The Study Area was one of nine Focus Areas identified by the DEQ during the 2008 Downtown Portland Sediment Evaluation (DEQ 2009) study. A preliminary assessment conducted in 2010 identified the most likely sources of contamination to the site as the upland properties within the RM 13.5 drainage area, as well as potential releases during historical overwater activities. Impaired sediment and surface water from upstream sources were also identified as potential historical sources of contamination within the Study Area. In 2011, PGE prepared a Remedial Investigation Report (RI) (URS 2011) to determine if contaminants found in surface and subsurface sediments, including polychlorinated biphenyls (PCBs), dioxins/furans, pesticides, and some metals (copper, lead, mercury, zinc), exist at concentrations potentially posing an unacceptable risk to human health and ecological receptors. Based on the results of the RI, PGE prepared a Feasibility Study (FS) (URS 2014) report describing the remedial alternatives developed, screened, and evaluated to determine the appropriate cleanup action for RM 13.5. The Final FS recommended installation of an isolation cap as the preferred RA for the RM 13.5 Study Area. This RA was selected by DEQ in the ROD, in accordance with Oregon Revised Statutes (ORS) 465.314 and Oregon Administrative Rules (OAR) 340-122-0090 (DEQ 2015). The purpose of the RA is to address the contaminant of potential concern (COPCs) that are the indicator chemicals within the surface sediment in the Study Area. These include the following: total PCBs, total dioxins/furans (total equivalency factor [TEQ mammalian]) and total DDx (i.e., sum of dichlorodiphenyldichloro-ethane [DDD] and its breakdown products dichlorodiphenyldichloro-ethylene [DDE] and dichlorodiphenyltrichloro-ethane [DDT]) (URS 2011). Maximum COPC concentrations for indicator chemicals in the Study Area surface sediment, before implementation of the RA, were as follows: total PCBs (134 µg/kg), total dioxins/furans (20.0 ng/kg), and total DDx (14.9 µg/kg). Greater than 89% of the surface area in the Study Area is above the mean upriver background concentrations (MUBCs) in the surface sediment for the indicator chemical COPCs, based on surface weighted average concentrations (SWACs). The RA includes the installation of an isolation cap over a sediment area sufficient to reduce surface sediment indicator chemical COPCs to near or below MUBCs on a SWAC basis. The SWAC analysis from the FS is provided in Table 1-1. The Remedial Action Objectives (RAOs) and Remedial Goals (RGs) for the project are presented in Table 1-2, and described in more detail in the RD Report and the Final FS.

1.3 Approvals and Permits The following permits, certifications, approvals, and notifications were required before the start of construction and are included in Appendix A: • DEQ:

o Approval of the final design. DEQ conditionally approved the RD Report on September 9, 2015. • DSL:

o Access Agreement and Easement o Joint Permit Application documenting compliance with Oregon’s Removal/Fill Law (ORS Chapter 196)

1-2 SECTIONONE Introduction

• U.S. Army Corps of Engineers (Corps): Joint Permit Application included the following additional permitting documents for review by the National Marine Fisheries Service (NMFS), DSL, and DEQ:

o Nationwide 38 Permit o Inadvertent Discovery Plan (IDP) o Oregon State Historic Preservation Office (SHPO) National Historic Preservation Act (NHPA) Section 106 Clearance

o Endangered Species Act (ESA) Section 7 Interagency Consultations between the Corps and National Oceanic and Atmospheric Administration (NOAA) Fisheries Service/U.S. Fish and Wildlife Service (FWS)

o Clean Water Act Section 401 and 404 permits • City of Portland, including the Bureau of Development Services (BDS) and Bureau of Environmental Services (BES):

o Compliance with Portland City Code issued in the form of a Remedial Action Exempt Review: Title 10 for erosion and sediment control, Title 17 for public improvements, Title 24 Chapter 24.50 for flood hazard areas, Title 24 Chapter 24.70 for clearing, grading, and erosion control, Title 33 for planning and zoning

1.4 Project Team and Roles and Responsibilities Roles and responsibilities of the key team members are summarized below.

• Project Owner: PGE. Chris Bozzini, Project Manager. • DEQ: Dave Lacey, Project Manager. • Principal in Charge: Anne Fitzpatrick, LHG (AECOM). Responsible for overall project implementation. • Project Manager: Jason, Palmer (AECOM). Responsible for overall project management including project planning, PGE and DEQ coordination, construction oversight, health and safety, and documentation and reporting. • Senior Project Engineer: Bill Gerken (AECOM). Responsible for overall compliance, project design specifications, and design implementation. • Project Engineer: Heidi Nelson, PE (AECOM). Responsible for ensuring compliance with the project plans and responding to contractor design questions. • Field Construction Oversight: Darrell Thompson (AECOM). Responsible for supervising daily/weekly water quality monitoring, coordination of topographic and bathymetric surveys, project plan/report review and inspections, quality control (QC) reporting, corrective measures tracking, and contract compliance.

1-3 SECTIONONE Introduction

• General Contractor: HME Construction, Inc. (HME). Responsible for construction project management and sediment isolation cap construction. HME was also responsible for subcontracting Ballard Marine Construction for dive operations, Solmar Hydro for bathymetric surveys, and Northern Resource Consulting, Inc. for turbidity meter installation. • Contractor Health, Safety, and Compliance Manager: Dave Godel (HME). Responsible for compliance with the contractor Health and Safety Plan. • Contractor Project Manager: Alan Park (HME). Responsible for coordinating all administrative functions for the project. • Contractor Project Superintendent: Darrell Jamieson (HME). Responsible for implementing all health and safety policies, work plans, environmental controls, survey work, and subcontractor work, and ultimately responsible for the quality completion of the work. Darrell was the designated on-site Construction Supervisor.

1-4 SECTIONTWO Remedial Design

2.0 REMEDIAL DESIGN The RD for the project required placing a sediment isolation cap over approximately 48,547 ft2 or 1.11 acres. The proposed isolation cap extent (isolation sand layer and armor layer) is shown on Figure 2-1. The purpose of the isolation cap is to prevent human health and ecological receptor exposure to the impacted sediments and also reduce migration (mobility) of the COPCs to meet the project RAOs and RGs immediately after construction completion. A detailed description of the RAOs and RGs, indicator chemical evaluation, chemical transport modeling, isolation cap modeling, scour modeling, propeller wash modeling, and remedy development can be found in the FS (URS 2014) and/or RD Report (AECOM 2015). The RD for the sediment isolation cap proposed three main elements: debris removal, placement of the isolation sand layer, and placement of the armor layer to protect the cap against erosion. A summary of each element is provided below, as presented in the proposed design. Deviations from the intended design are summarized in Sections 4.2.4 and 4.3.4, Deviations from Remedial Design.

2.1 Debris Removal Large debris within the isolation cap footprint could potentially reduce the long-term effectiveness of the cap by either breaching the cap and causing additional scour at the surface, or reducing the thickness of the cap in localized areas below what is required for chemical isolation. Large debris was considered to be anything with a height extending above the sediment surface of approximately 1 foot or more, and/or resting on the sediment surface and larger than 1 foot in any dimension. Therefore, all large debris within the surface of the proposed cap area would be removed prior to cap installation. The presence of small debris and piles below the sediment surface will add stability to the sediment below the cap (U.S. Environmental Protection Agency [USEPA] 2005); no debris removal is required for debris that is below the sediment surface. Debris and objects within the study area were initially identified using a multi-beam survey with the backscatter during June 2013. A follow-up debris survey was conducted by Solmar Hydro on February 24, 2015. Larger debris items, including large woody debris, concrete, and rock outcroppings, were identified during the 2015 survey. The results of these surveys were combined to identify known debris requiring removal before cap placement; these results are presented in Appendix B of the RD Report (AECOM 2015).

2.2 Isolation Cap Isolation cap modeling was conducted to determine the required isolation cap thickness, by estimating the time to achieve steady state flux conditions in the isolation cap layer and to predict the breakthrough time from the underlying sediment for COPCs into the biologically active zone of the isolation sand layer. Modeling indicated that a 1.97-foot thick chemical isolation layer of sand placed across the capped area would be protective for 500–1,000 years; the design accounted for a reduction of up to 5.5 inches of effective cap thickness due to cap consolidation and mixing with the native sediments. Additional details of the cap isolation model are presented in the FS (URS 2014) and RD Report (AECOM 2015). Based on the modeling results, the RD required an isolation sand layer placed to an average thickness of 1.97 feet with an allowable margin of error of up to 10%, resulting in a minimum allowable thickness of the isolation cap sand layer of 1.77 feet thick. The isolation cap thickness would have an average overall

2-1 SECTIONTWO Remedial Design

thickness above the minimum thickness of 1.77 feet over at least 90% of the isolation cap area. No areas of the isolation sand layer would be below an absolute minimum thickness of 1.67 feet, which included an allowance for consolidation and is the minimum thickness needed for chemical isolation. Laboratory chemistry results of the proposed sand layer material would be reviewed and approved by the project engineer prior to placement. The design slope was conservatively specified to be 3H:1V in the RD in order to maintain cap stability during placement, allowing for a gradual buildup of the sand isolation layer in steep slope areas and ensuring a sufficient thickness across the entire cap area. The 3H:1V slope condition was also used to identify portions of the cap (steep slope areas) where more than the minimum amount of sand (the primary design compliance metric) would need to be placed to successfully install the cap. The isolation sand layer would be installed using a conventional clam-shell bucket deployed by a crane, in approximately 1-foot lifts or less to minimize sediment disturbance and resuspension. Regular bathymetric surveys would be conducted to continually monitor sand thickness and identify areas of insufficient thickness. Following placement of the first and second 1-foot layers, sediment cores would be collected to visually confirm sand thickness and validate bathymetric survey results. Due to the relatively steep slopes within the cap area, several portions of the cap would be considerably thicker than 2 feet to achieve the 3H:1V design grade. A final bathymetric survey, compared against the post-debris bathymetric survey, would be conducted to verify the final isolation sand layer thickness.

2.3 Armor Stone Following placement and completion of the isolation sand layer, a protective armor layer would be installed to prevent erosion of the sand material. The required armor stone size(s) were determined by evaluating the potential erosive forces at the site from water velocity, propeller wash, and wave and wake impacts. The water velocity calculations evaluated a 100-year storm event, and the propeller wash and wave/wake analyses utilized assumptions based on actual vessels operating near the Study Area. The detailed armor stone calculations are presented in the FS (URS 2014) and RD Report (AECOM 2015). The RD identified the need for three types/sizes of armor stone across the cap area. Along the shoreline above a +3-foot elevation (North American Vertical Datum [NAVD] 88), a 2.5-inch angular gravel was required to resist waves and wakes (shoreline armor). The main body of the cap required a 0.5–2.5 inch rounded gravel (with a mean of 1.5 inches) to resist the water velocities generated by a 100-year flood event (cap armor). The offshore, upstream, and downstream edges (or toe) of the cap required a 3-inch diameter (rounded) stone to provide additional toe support and geotechnical stability, and resist the water velocities generated by a 100-year flood event (toe armor). Laboratory gradations for each armor stone type would be reviewed and approved prior to placement. The armor stone for the shoreline and cap armor layers would be placed to an average thickness of 0.66 foot. The armor layer had an allowable placement tolerance of up to 10% of the design elevation, resulting in a minimum allowable thickness of 0.6 foot. The armor stone thickness would have an average overall thickness above the minimum thickness of 0.6 foot over at least 90% of the isolation cap area. No areas of the armor layer would be below an absolute minimum thickness of 0.43 foot. A final bathymetric survey, compared against the post-isolation sand layer bathymetric survey, would be conducted to verify the final armor layer thickness.

2-2 SECTIONTWO Remedial Design

The toe armor would be placed as a buttress just beyond the extent of the isolation cap to provide a structural base for cap stability, and to provide erosion protection at the toe of the cap. The toe armor would be approximately 2.6 feet thick at its thickest point based on design estimates; no average or minimum design thicknesses were required. The RD specified a design slope of 3H:1V for the cap body armor and 2H:1V for the shoreline and toe armor. The cap body armor design slope was based on the assumption that it would be placed in a uniform layer on top of the underlying isolation sand layer, which would already be at a 3H:1V slope. The specified shoreline and toe armor design slope of 2H:1V allowed for steeper slopes along the fringes of the cap where an abrupt edge of the isolation sand layer would need to be covered.

2-3 SECTIONTHREE Pre-Construction Activities

3.0 PRE-CONSTRUCTION ACTIVITIES Pre-construction activities included health and safety planning, engineering controls setup and baseline monitoring, equipment mobilization, debris removal, and a post-debris removal bathymetric survey. Pre- construction activities began on September 15, 2015 with placement of the turbidity meters, and concluded on September 24, 2015 following the post-debris removal bathymetric survey. Each activity is summarized below.

3.1 Health and Safety Each company that participated in field activities during construction developed a Health and Safety Plan (HASP) addressing those activities they would perform on-site, in accordance with their own health and safety policies and procedures, as well as relevant regulatory programs (e.g., Occupational Safety and Health Administration).

Each morning prior to commencing work activities, all on-site workers met to discuss the planned activities for the day, the risks associated with those activities and how to mitigate them, and coordination and communication requirements throughout the day. If unplanned work or unexpected conditions were encountered, the field teams stopped work to evaluate the new conditions and any additional potential safety concerns. The daily safety tailgate meetings were documented each day by AECOM and HME in the Daily Field Reports (DFRs) (Appendix B).

3.2 Baseline Environmental Monitoring and Engineering Controls Environmental monitoring was conducted prior to and during construction activities as required by the RD Report and applicable permits. Turbidity, noise, and dust monitoring were conducted prior to field activities (baseline monitoring) and during construction. In addition, a floating debris boom was installed downstream of the work area to prevent debris from moving off-site during debris removal and construction activities.

3.2.1 Baseline Turbidity Monitoring Prior to initiating debris removal, one upstream and one downstream turbidity monitoring station were deployed. Northern Resource Consulting, Inc. (NRC) was contracted to install and maintain the turbidity meters. The turbidity meters used were YSI EX02 Multi-parameter 6-Port Water Quality Sondes, connected to a floating platform with batteries, solar panels, and cellular data buoys to allow for real-time data collection. Each sonde was secured to the river bottom using a two-point anchor system. A schematic of the turbidity monitoring stations is shown in Appendix C (Sheet F07), and the location of the meters is shown on Figure 3-1. The meters were calibrated prior to installation; the calibration forms are provided in Appendix D. The turbidity meters were installed on September 15, 2015. The locations and depths of the turbidity meters were adjusted in the field to achieve sufficient water depth during low tide, and so they were not in the path of regular vessel traffic (e.g., jet boat tours). The turbidity meters were set to hang from the floating platform at a depth approximately 50% of the total water depth. Baseline turbidity readings were collected on September 16 and 17 (prior to debris removal activities) in accordance with permit requirements. Baseline turbidity readings for the turbidity monitoring stations can be found in Appendix D. Baseline turbidity readings were low, ranging from approximately 1 to 3 Nephelometric turbidity units (NTUs).

3-1 SECTIONTHREE Pre-Construction Activities

Following installation and testing of the turbidity meters, a field test was performed on September 18, 2015 to confirm that the upstream turbidity meter was not affected by cap installation (resulting in a higher “background reading”). This test was conducted at the request of NMFS as a compromise to locating the meter farther upstream. Several 5-gallon buckets of sand were dumped into the river 50 feet downstream of the upstream (background) meter to evaluate whether a change in turbidity was observed. No significant change in turbidity readings was observed; therefore, the position of the upstream turbidity meter was deemed appropriate.

3.2.2 Baseline Noise Monitoring Baseline noise monitoring was conducted on September 17 and 18, 2015, using a 3M™ NoisePro™ dosimeter. Baseline readings were collected three times each day at the locations shown on Figure 3-1, and generally ranged from 61 to 65 decibels (dB). The baseline noise monitoring results are presented in Appendix E.

3.2.3 Baseline Dust Monitoring Baseline dust monitoring was conducted on September 22 and 23, 2015, prior to implementation of sand placement (primary potential source of fugitive dust). Dust monitoring was conducted using a TSI® 8530 DustTrak™ II dust monitor. Baseline readings were collected three times each day at the locations shown on Figure 3-1, and generally ranged from 0.001 to 0.044 milligrams per cubic meter of air (mg/m3). The baseline dust monitoring results are presented in Appendix F.

3.2.4 Floating Debris Boom A 12-inch floating debris boom was installed downstream of the work area prior to debris removal activities. One end of the boom was anchored to the shoreline downstream of the work area, and the other end was anchored to the downstream end of the derrick barge. Using this configuration, the debris boom was kept downstream of all project activities, without having to relocate the boom during construction. A schematic of the debris boom is shown in Appendix C (Sheet F07).

3.3 Equipment Mobilization Equipment mobilization to the site began on September 16, 2015, with the arrival of a derrick spud barge and crane, a materials barge, a tugboat, and a support boat. Throughout construction, HME utilized a 60- ton and a 200-ton crane, both on individual 100-foot derrick spud barges, to allow construction without spudding in the cap area; four material transport barges ranging from 1,500 to 3,000 ton capacity; two tug boats; and multiple support boats. In addition, an upland front-end loader was used for material handling and consolidation on the barges.

3.4 Debris Removal, Sampling, and Disposal Debris removal was initiated on September 18, 2015, following equipment mobilization and baseline environmental monitoring. Previous multi-beam bathymetric surveys in 2013 and 2015 were used to identify debris within the cap area to be investigated for removal. Divers from Ballard Marine Construction navigated to each debris location to verify the type of debris present and the debris elevation above the mudline. All identified debris protruding at least 1 foot above the sediment surface was confirmed for removal to prevent debris from compromising the integrity (and thickness) of the isolation sand layer.

3-2 SECTIONTHREE Pre-Construction Activities

Loose debris laying on the sediment surface was extracted using HME’s crane. Divers secured the crane line to the debris using slings and chains, and the debris was hoisted out of the river and onto a water-tight materials barge for storage and disposal transport. Debris that was partially buried in the sediment was cut as close to the mudline as possible, using a diver-operated pneumatic saw or shears, and then hoisted out. Debris was lifted slowly from the river bottom to minimize sediment disturbance or resuspension. Significantly more debris required removal than anticipated, as additional debris was either identified by the divers during their initial survey or was exposed during removal of other debris. Approximately 55 tons of debris, primarily wood with some concrete and miscellaneous items, was removed from the river bottom (the design estimate was 20 tons). Interim and final diver and bathymetric surveys were completed throughout the removal process to confirm that all debris was identified and removed. Debris removal was completed on September 24, 2015. Following debris removal, the debris barge was taken to HME’s offloading facility along the Columbia River in Vancouver, Washington. Excess sediment was washed from the debris to allow samples of the debris to be collected for chemical analysis. Three samples were collected on October 6, 2015 by Maul Foster and Alongi; two samples were collected from the wood debris, and one sample was collected from the concrete. Following receipt of the analytical results, which indicated the debris was considered non- hazardous material, the debris was transported to the Wasco County Landfill in The Dalles, Oregon. The debris analytical results and disposal tickets are presented in Appendix G. The wash water used to clean the debris was stored at HME’s offloading facility; it was eventually combined with wash water from equipment decontamination and sampled for disposal. Disposal information for the wash water is provided in Section 4.5, Demobilization.

3.5 Post Debris Removal Bathymetric Survey Following debris removal activities on September 23, 2015, a high resolution multi-beam bathymetric survey was conducted by Solmar Hydro to obtain a pre-construction baseline elevation against which to measure sand placement thickness. The post-debris removal elevations are shown in Figure 3-2, and the survey data are presented in Appendix H. Prior to conducting the post-debris removal bathymetric survey, however, seven additional wooden piles were identified for removal. Given the limited anticipated impact on the bathymetric survey and the favorable tide conditions on September 23, 2015, the project team decided to conduct the bathymetric survey prior to the seven piles being removed. The seven piles were removed the following morning, on September 24, 2015.

3-3 SECTIONFOUR Construction Activities

4.0 CONSTRUCTION ACTIVITIES Construction activities included fill material verification, placement of the isolation sand layer, placement of the armor layer, confirmation bathymetric and diver surveys, and equipment demobilization. Construction activities were initiated on September 24, 2015, and concluded on November 2, 2015 with the removal of the turbidity meters; Table 4-1 presents a chronology of the work sequence. In-water work was completed before the close of the allowable in-water work window (July 1 to October 31). Each activity is summarized below.

4.1 Fill Material Verification As required by the RD Report, prior to placement of any fill materials, gradation or chemical analytical samples were collected for the isolation sand layer and armor materials. All materials were obtained from Knife River Materials, Waterview Pit in Columbia City, Oregon, located approximately 30 miles from the site; the materials were loaded onto barges from this location for transport to the site. The sand and gravel consisted of clean imported material and were free from roots and other loose organic matter, trash, debris, snow, ice, or frozen materials. The following is a summary of each material and the relevant testing and approval (if required).

4.1.1 Isolation Cap Sand Layer Material The isolation sand layer material was a medium to coarse grain sand that was dredged from the Columbia River as part of the channel deepening project between Longview, Washington, and Rainier, Washington. The material was transported to and stored at the Waterview Pit until transport to the site. Two samples of the sand (one per every ~5,000 cubic yards [cy]) were collected and analyzed for site COPCs and other chemicals. The laboratory report and summary table were provided to DEQ for review and approval; DEQ approved the sand material via email on September 22, 2015. Appendix I provides DEQ’s approval email, the summary table, and analytical laboratory report.

4.1.2 Armor Stone Material The armor layer included toe armor, cap armor, and shoreline armor stone. The toe armor material was roughly 1–3 inch rounded gravel, obtained from Knife River. One gradation sample was collected for the toe armor layer material to confirm that the material size met the design specifications. The gradation results are included in Appendix J. No analytical samples were required for any of the armor stone material. The cap armor material (covering the main body of the isolation sand layer) was roughly ¾–2 inch rounded gravel, obtained from Knife River1. One gradation sample was collected to confirm that the material size met the design specifications. The gradation results are included in Appendix J. The shoreline armor material (covering areas above +3 feet elevation) was roughly 1–2 inch angular gravel, obtained from Knife River1. One gradation sample was collected to confirm that the material size met the design specifications. The gradation results are included in Appendix J.

1 The final design specified a maximum stone size of 2.5 inches.

4-1 SECTIONFOUR Construction Activities

The armor stone sizes utilized during construction at RM 13.5 are generally smaller than specified in the RD. Smaller stone sizes were utilized based on the material available prior to construction from local sources. The smaller stone sizes, while slightly outside of the design specifications, do meet the design intent and will be protective of future erosion/scour. Appendix K provides additional detail on the armor stone sizes presented in the RD and those installed at the site, as well as additional calculations performed by AECOM to confirm that the installed armor stone sizes are protective.

4.2 Isolation Sand Layer Construction Construction of the isolation sand layer was initiated on September 24, 2015, and concluded on October 29, 2015. As described in Section 2.2, Isolation Cap, the RD required a thickness 1.97 feet of sand for the isolation layer, not more than 10% of the cap below 1.77 feet, and an absolute minimum sand thickness of 1.67 feet. The design slope was conservatively specified to be 3H:1V in the RD in order to maintain cap stability during placement.

4.2.1 Placement Methods To track the placement and volume of the sand material, the isolation sand layer area was divided into 10- foot by 28-foot grid cells by the contractor; an electronic georeferenced copy of the grid was downloaded to the field computer in the crane cab using HYPACK® software. The grid layout is shown on Figure 4- 1. The size of the grid cells was selected to allow one bucket of material to cover each grid cell with approximately 1 foot of material (~12 cy per cell). The bucket used for the project was an Atlas clam- shell bucket, which held 12 cy of material when heaped, and 10 cy of material when level. For each cell, the operator positioned the bucket at one end of the cell, using a GPS beacon attached to the top of the derrick boom for positioning. The operator would crack open the bucket and slowly swing the bucket across the entire cell, allowing relatively uniform placement across the entire cell. The bucket was kept just above the water surface during material release to allow the operator to observe the amount of material coming out of the bucket, which helped to maximize uniform placement. Following completion of each cell, the operator manually labeled each cell as complete within grid layout. The project superintendent (located in the support office on the barge) would confirm these activities at the end of each day with a second computer and software package. Pictures of the placement process are shown in Figure 4-2.

4.2.2 Placement Sequence As previously described, the isolation sand layer was placed in approximately 1-foot lifts to minimize sediment disturbance and resuspension. The first 1-foot lift was started on September 24, 2015 and completed on September 25, 2015, with placement of one bucket of sand in each grid cell. A single-beam bathymetric survey was conducted to verify that a 1-foot lift thickness was sufficiently achieved. The following work day (September 28, 2015), the first four confirmation diver cores (SC-01 through SC-04) were collected and processed. The depth of sand in the cores ranged from 0.8 to 1.3 feet of sand, with mixing zone depths of 0 to 2 inches. The locations of the sediment cores and the core logs are presented in Appendix L. Based on this information, and the positive correlation between the bathymetric survey results and sediment core measurements, the first lift was considered generally complete. There were several small areas near the perimeter of the cap, especially along the top of steeper slope areas, that did

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not have 1 foot of sand based on the bathymetric survey. The project team decided to make additional passes over these grid cells during placement of the second lift. The second 1-foot lift was started on September 28, 2015 and was generally completed on September 29, 2015. A single-beam bathymetric survey was conducted on September 28, 2015 to verify that the second 1-foot lift thickness was sufficiently achieved. The majority of the cap area did show approximately 2 feet of sand thickness; the project team decided to move forward to the second set of sediment cores to confirm the sand thickness calculated from the surveys. Two sediment cores (SC-05 and SC-06) were collected on September 30, 2016. Collecting the cores was more challenging for the divers given the greater thickness of sand, resulting in lower percent recoveries. However, even with the lower recovery, the cores showed a sand thickness of 1.6 to 1.8 feet. Extrapolating for poor recovery, and based on the bathymetric surveys, it was determined that sufficient thickness had been obtained over the majority of the cap. As with the first 1-foot lift, several areas (but less than 10% of the total cap area) near the top of the steep slopes showed insufficient thickness. In some instances, these areas had less sand thickness than after the first 1-foot lift was completed. The general consensus was that the sand was sloughing down the steeper slopes because a slope sufficient for the sand to remain stable had not been established. Following the second 1-foot lift, the field team began filling in the slope areas where more than 2 feet of sand was anticipated in the RD, and making additional passes over areas with less than the minimum required sand thickness. Additional sand placement activities began on September 28, 2015 and continued through October 23, 2015. The pace of work decreased substantially during this time due to the continual need to move the derrick barge and to conduct interim surveys and review results. By October 7, 2015, approximately 85% of the cap area was covered with at least 2 feet of sand. From October 8, 2015 to October 23, 2015, the field team focused on areas of steeper slopes where the sand continued to slough down the slope. Two primary areas continued to see sloughing regardless of the amount of sand placed. These two areas, in the northeast corner, are shown in red color on Figure 4-3; those areas where the final cap thickness did not meet the minimum thickness requirement are shown as a red hatch. Each evening following sand placement, the sand placed in these areas seemed to be displaced by either sloughing or the water flow from changing tidal cycles. On October 23, 2015, the decision was made to place as much sand as possible in these areas, conduct a bathymetric survey, and then immediately cap the areas with armor stone to prevent the further loss of sand material over the weekend. DEQ was informed of this decision early the following week during an October 27 phone call and provided verbal agreement with the decision. In total, less than 1% of the total cap area did not meet the minimum cap thickness of 1.67 feet, and less than 2% of the cap was less than the required average thickness of 1.97 feet. The DFRs (Appendix B) contain a daily record of sand placement per grid cell, and the results of interim bathymetric surveys to confirm isolation sand layer thickness. Table 4-2 summarizes the volume of each type of material placed as part of the sediment isolation cap.

4.2.3 Final Confirmation Bathymetric Survey Multiple multi-beam, single-beam, and topographic surveys were conducted throughout the sand material placement to confirm cap thickness and ongoing progress. The final confirmation survey dataset, provided in Appendix M, was compiled from multiple survey events as separate areas of the cap were approved for armor stone placement. Appendix M includes the final merged survey dataset, as well as the

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data collection method used and the date it was collected. The final as-built isolation sand layer is presented in Appendix C (Sheet F04).

4.2.4 Deviations from Remedial Design There were several minor deviations from the isolation sand layer RD (see Section 2, Remedial Design), as described in more detail below. Cap Extent and Volume Due to sloughing in steep slope areas, the amount of sand material placed and the extent of the sand material was greater than anticipated in the RD. The RD assumed a total sand material volume of 6,650 cy; the actual total placement of sand material was 8,829 cy. The RD assumed a total isolation cap footprint of 1.1 acres; the actual isolation sand layer was placed over approximately 1.24 acres. These variations exceeded the permitted volume and extent in the Corps Nationwide 38 Permit; AECOM communicated this permit exceedance to the Corps on November 3, 2015 following a site visit by the Corps on October 23, 2015. The Corps issued PGE a Notice of Noncompliance on November 16, 2016, documenting the exceedance. No further action was required of the team by the Corps. Cap Thickness Over 99% of the isolation cap layer achieved the minimum required thickness of 1.67 feet, and over 98% achieved the required average thickness of 1.97 feet. These areas that did not meet the minimum thickness were located at the crest of steep slopes where sand would continually slough or wash away. DEQ was informed of this deviation on October 27, 2015 and provided verbal agreement with the decision to stop placing sand and cover the area with armor. Fill Slope A review of the post-construction top of sand elevation data indicated that approximately 69% of the isolation sand layer achieved the specified design slope of 3H:1V or less (i.e., shallower), and approximately 80% was less than a 2.8H:1V slope. The steepest slope areas were approximately 2.5H:1V. The majority of areas steeper than 3H:1V were located near the crest of the slope, in areas where the preconstruction slopes were as steep as 1H:1V. It’s possible that the steep underlying slopes contributed to the steeper than anticipated final slope. These steeper areas are generally isolated and no greater than 40 feet across (perpendicular to the slope). The final as-built isolation sand layer slopes are shown on Figure 4-4. While not all of the sand isolation layer met the design slope of 3H:1V, the as-built slopes were sufficient to achieve a stable isolation sand layer that met the primary design compliance criteria, providing sufficient sand thickness for chemical isolation. Because the 3H:1V slope was primarily incorporated in the design as a constructability consideration and not for long-term stability, having limited areas that did not meet the design slope will not affect the long-term stability or performance of the cap. The sand was able to maintain a slightly steeper stable slope during construction when it was the least consolidated. Following placement of the isolation sand layer and armor layer, the isolation sand layer continued to consolidate and gain additional strength. It is anticipated that the sand layer will therefore remain stable. For these reasons, following confirmation that the design thickness was met, placement of sand in steeper slope areas was stopped in order to avoid overloading the slopes, resulting is these areas not achieving the design slope.

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Survey Methodology The RD specified the use of multi-beam survey for the final confirmation surveys, along with topographic surveys for those areas above water. Due to shallow water conditions following material placement, a single-beam survey was used in shoreline areas too shallow to use multi-beam equipment, but too deep to safely collect topographic points. In addition, a single-beam survey was used to confirm several small areas in deeper water; DEQ approved the use of a single-beam survey in an October 14, 2015 email (Appendix I).

4.3 Armor Layer Construction Construction of the armor layer was initiated on October 16, 2015, following confirmation of sufficient sand thickness over approximately 50% of the cap. Three types of armor stone (shoreline armor, cap armor, and toe armor) were placed over the cap area as described in Section 2.3, Armor Stone. The RD required an average thickness of 0.66 foot of cap and shoreline armor stone, with not more than 10% of the armor layer below 0.6 foot and an absolute minimum thickness of 0.43 foot. The RD specified a maximum 3H:1V fill slope for the cap armor and a 2H:1V for the shoreline and toe armor.

4.3.1 Placement Methods The placement methodology for all of the armor stone material was the same as the methods used for placement of the isolation sand layer (described in Section 4.2.1, Placement Methods), with the exception of nearshore placement above the river water level. For areas that were regularly above the water line following sand placement, the shoreline armor stone frequently mounded and did not achieve uniform coverage from the bucket pass. The field team used rakes and shovels to spread out the shoreline armor stone into an even, level layer. Each grid cell was staked to allow the field team to visually identify each cell boundary. Pictures of the armor placement process are shown in Figure 4-5.

4.3.2 Placement Sequence Armor stone placement was initiated on October 16, 2015. Placement activities were conducted in approximately 0.66-foot lifts following the approval of sand thickness requirements. The RD specified one round of armor stone placement following the completion of the entire isolation sand layer. However, given the difficulty achieving sand thickness in some areas, armor stone placement was allowed to take place as a sequential approach; this allowed the field team to cover and protect the approved isolation sand layer areas as quickly as possible to prevent potential erosion, as well as continue construction activities while waiting for bathymetric surveys of outstanding isolation sand layer areas. Generally, cap armor stone placement started at farthest offshore extent of the cap and worked upslope. Along the cap boundary, the cap armor or shoreline armor was placed first (their footprints did not overlap), followed by the toe armor to allow for complete coverage of the cap armor or shoreline armor by the toe armor. The toe armor was placed on top of the cap armor or the shoreline armor, with an overlap of an approximately 5-foot wide area along the edges. Daily bathymetric surveys were conducted and compared against the final isolation sand layer elevation to confirm the armor stone thickness. The final isolation sand layer elevation was also used to determine the area for shoreline armor placement (above +3 feet elevation NAVD 88). Armor stone placement was completed on October 29, 2015, following approval of the final survey (shown on Figure 4-6). Over 99% of the armor stone layer exceeded the minimum thickness requirement

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of 0.43 foot, and more than 97% of the area exceeded the required average thickness of 0.66 foot. As shown on Figure 4-6, the areas that did not meet the minimum thickness are very small and all less than approximately 10 ft2. The decision was made by AECOM and PGE not to continue armor stone placement, as the size of the individual areas was much smaller than the bucket used to place the material. The DFRs (Appendix B) contain a daily record of armor stone placement (and type) per grid cell, and the results of interim bathymetric surveys to confirm armor stone thickness. Table 4-2 summarizes the volume of each type of material placed as part of the sediment isolation cap.

4.3.3 Final Confirmation Bathymetric Survey Multiple multi-beam, single-beam, and topographic surveys were conducted throughout the armor stone placement to confirm armor thickness and ongoing progress. The final confirmation survey dataset is provided in Appendix N, compiled from multiple survey events. Appendix N includes the final merged survey dataset, as well as the data collection method used and the date it was collected. The final as-built armor layers are presented in Appendix C (Sheet F05).

4.3.4 Deviations from Remedial Design There were several minor deviations from the armor layer RD, as described in more detail below. Armor Extent and Volume The volume of the armor stone placed exceeded the estimated volume in the RD. The RD assumed a total armor material volume of approximately 1,900 cy; the actual total placement of material was 2,790 cy. The RD assumed a total armor stone footprint of 1.1 acres; the actual armor stone layer was placed over approximately 1.27 acres. These variations also exceeded the permitted volume and extent in the Corps Nationwide 38 Permit, as described in Section 4.2.4, Deviations from Remedial Design. Armor Thickness Approximately 0.6% of the armor layer did not achieve the minimum required thickness of 0.43 foot. Most of the areas were less than 5 ft2 and in many instances may be the result of data contouring, not actual armor thickness. DEQ was informed of this deviation on October 27, 2015 and provided verbal agreement with the decision not to place additional armor stone over these very small areas. Armor Stone Size As previously discussed in Section 4.1.2, the armor stone installed at RM 13.5 was generally smaller than specified in the RD due to material availability during construction. The smaller armor stone does meet the design intent, and as discussed in Appendix K the armor stone is of sufficient size to provide long term scour protection. Fill Slope The goal during construction was to place a relatively uniform layer of armor stone across the isolation sand layer and not overload it with thicker placement areas. Because the isolation sand layer was steeper than 3H:1V is some areas, so are limited areas of the cap body armor. As determined by the final armor layer elevation data, approximately 66% of the cap body armor achieved a slope of 3H:1V or less (shallower), and approximately 74% was less than a 2.8H:1V slope. The steepest slope areas were approximately 2.4H:1V. The majority of areas that did not achieve a 3H:1V for the cap body armor were

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due to and co-located with areas where the isolation sand layer did not meet a 3H:1V slope, and some areas were less than 3H:1V were within the shoreline and toe armor layers and meet the design requirement of 2H:1V. The final as-built armor stone slopes are shown on Figure 4-7. The design slope of 3H:1V for the cap body armor was primarily based on the assumption that the underlying isolation sand layer would be at a 3H:1V slope, and not based on slope stability requirements. Overall, the armor stone has a higher friction angle, and is able to stand at a steeper slope naturally then the sand. As with placement of the isolation sand layer, the primary design compliance metric was based on a pre- determined thickness to provide erosion protection. Once the required design thickness was achieved, armor placement was halted in steep slope areas to prevent overloading the slopes. The as-built cap body armor layer will provide sufficient long-term scour protection. Armor Design for Toe of Cap Due to the greater extent of the isolation sand layer as a result of sloughing of the sand material during placement, the armor design for the toe of the cap was updated to account for a thicker sand layer around the edges of the cap. A toe armor blanket was placed over the cap armor and excess sand material, instead of a wedge or a buttress, to prevent future scour of excess sand outside of the armor layer from undermining the armor layer. The revised toe armor blanket design thickness was 12 inches, with a minimum thickness of 9 inches. The installed thickness was determined by comparing the final cap body armor or sand isolation layer elevations to the final toe armor elevations. Approximately 81% of the toe armor blanket met the average design thickness of 12 inches, approximately 95% met the minimum design thickness of 9 inches, and approximately 99% was greater than 6 inches. Areas with less than 9 inches of coverage are scattered in small (5 to 15 square foot) discontinuous portions of the toe armor. The modified design of the toe armor will fulfill all of the functions of the originally designed toe armor, namely protecting the outer edge of the cap from erosion. As built, the material is overlying a portion of the cap body armor and a portion of the sand placed outside the extent of the cap body armor. If the limited sand placed outside the cap area begins to erode, the toe armor is designed to settle, effectively providing the required erosion protection along the edge of the cap. A schematic of the updated toe armor design is shown in Appendix C (Sheet F07). Sequential Approach to Armor Placement As described above, the RD envisioned one complete lift of armor material placed over the entire project area at one time following the completion of the isolation sand layer. However, given the difficulty achieving sand thickness and stability in some of the steeper areas, armor stone placement was allowed to take place as a sequential area-by-area approach; this allowed the field team to cover and protect the approved isolation sand layer areas as quickly as possible to prevent potential erosion, as well as continue construction activities while waiting for bathymetric surveys of outstanding isolation sand layer areas. Final Sediment Core Confirmation The RD Report required that a final sediment core (SC-07) be collected to verify the armor layer thickness. Given the difficulty obtaining sufficient recovery from the second round of isolation sand layer cores, AECOM proposed to DEQ that a diver visually inspect the armor layer thickness at the location of core SC-07, and use a graduated measure stick to confirm the thickness. DEQ approved this methodology on October 5, 2015; DEQ’s approval email is provided in Appendix I. On October 27, 2015, a diver from

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Ballard Marine Construction navigated to a buoy dropped at the SC-07 coordinates, dug a small hole in the armor layer, and visually confirmed the depth of armor using a graduated measure stick. The total armor layer thickness was measured at 13 inches, and there was minimal (less than 1 inch) mixing between the sand and armor stone layers. The armor stone was then placed back into the hole. Shoreline Habitat Shelf During the October 23, 2015 Corps site visit, it was noted that the shoreline extent of the cap did not grade into the existing shoreline riprap, leaving a depression in which fish could possibly be stranded at low tide. After consultation with the Corps and NMFS, PGE agreed to place an additional 46 cy of shoreline armor in this area to create a level grade and eliminate the risk of fish stranding. This material was placed using the same methodology as the shoreline armor, and graded using shovels and rakes. The shoreline habitat shelf is shown on Figure 4-8.

4.4 Final Diver Inspection A final diver survey of the cap (armor layer) was conducted on October 27, 2015 by a diver from Ballard Marine Construction. The diver swam across pre-defined areas of the cap in a zig-zag pattern to verify complete coverage of the cap by the armor layer, and to identify any anomalies such as sloughing of the armor layer or bare spots. The approximate diver transects are shown on Sheet F08 of Appendix C. The diver collected video and provided a verbal narrative of his observations. The diver was able to visually confirm that the cap areas across all of the transects were covered by armor stone, and no anomalies were identified. The video is of poor quality and poor detail because of limited visibility in the water; therefore, the video is not included in this CCR.

4.5 Demobilization Following the completion of armor stone placement and final bathymetric surveys on October 29, 2015, HME began to move equipment off-site; heavy equipment demobilization was completed on October 29, 2015. Equipment was moved to their Vancouver, Washington facility where it was decontaminated. Decontamination water was combined with the wash water from the debris cleaning and sampled for disposal. Two samples were collected on November 3, 2015 and submitted for laboratory analysis. Following receipt of the analytical results, which indicated the water was considered non-hazardous material, the water was transported to Oil Re-Refining, Inc. for disposal. The wash water analytical results and disposal tickets are presented in Appendix O. The turbidity meters were the last pieces of equipment removed from the site; NRC removed the meters on November 2, 2015.

4.6 Environmental Monitoring Environmental monitoring was conducted throughout the project, in accordance with the RD Report and applicable permits. Three types of environmental monitoring (turbidity, noise, and dust) were conducted, as described below. Table 4-3 presents a summary of the environmental monitoring results.

4.6.1 Turbidity Monitoring Baseline turbidity monitoring was conducted for 2 days prior to in-water work activities, as described in Section 3.2.1, Baseline Turbidity Monitoring. Baseline turbidity levels ranged from approximately 1 to 3

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NTUs. The initial primary compliance criteria for turbidity allowed for a 10% increase between the upstream monitoring station and the downstream monitoring station, as established in the RD Report and as a NOAA Fisheries requirement in the Nationwide 38 Permit. Because of the very low baseline and upstream construction turbidity levels (1 to 3 NTUs), the initial allowable 10% increase was too low (as low as 0.1 NTU) to be reliably measured by the turbidity monitors. AECOM negotiated a revised compliance standard during a September 22, 2015 meeting. The revised compliance standard allowed for a 5 NTU increase above the upstream monitoring levels (background) if the background levels were below 50 NTUs. For background levels above 50 NTUs, the allowable increase was 10% above background. Turbidity was monitored at the beginning of each work day, and throughout the work day at 2-hour increments for compliance. Turbidity levels were monitored during all in-water activities on an hourly basis, although only ever other hour was considered a compliance monitoring event. Background turbidity levels never reached 50 NTUs; therefore, the appropriate compliance criterion was 5 NTUs above background. Downstream turbidity levels exceeded 5 NTUs above background several times during sand placement activities. These exceedances were immediately addressed by reducing material placement rates. In all cases, turbidity levels returned to below 5 NTUs above background before the following compliance monitoring event; therefore, agency notification was never required. The turbidity monitoring results are presented in Appendix D.

4.6.2 Noise Monitoring Baseline noise monitoring was conducted for 2 days prior to implementation of construction activities, as described in Section 3.2.2, Baseline Noise Monitoring. Baseline noise monitoring levels ranged from 61 to 65 dB, driven mainly by background freeway noise. Construction noise levels were required to remain below the allowable commercial and industrial noise limit in Multnomah County, which is less than 70 dB between 7 a.m. and 10 p.m. These served as action levels for the project. Noise monitoring during construction was conducted once per week in accordance with the RD Report requirements. Monitoring was conducted adjacent to the work area along the Eastbank Esplanade. The highest noise level recorded during construction was 65.9 dB, which was below the Multnomah County limit of 70 dB, and similar to baseline readings. The construction noise monitoring data are presented in Appendix E, and the monitoring locations are shown on Figure 3-1.

4.6.3 Dust Monitoring Baseline dust monitoring was conducted for 2 days prior to implementation of construction activities, as described in Section 3.2.3, Baseline Dust Monitoring. Baseline dust monitoring levels ranged from 0.001 to 0.044 mg/m3. Dust levels were required to stay below 3 mg/m3 at the site boundary, and 10 mg/m3 in the vicinity of the workers. These served as action levels for the project. Additional monitoring was required if visible dust was present. Dust monitoring during construction was conducted once per week as instantaneous discrete samples in accordance with the RD Report. Monitoring was conducted at two locations adjacent to the work area along the Eastbank Esplanade, and at an upstream and downstream location. At no time during construction activities was visible dust present. The highest dust reading recorded was 0.057 mg/m3, which is below action levels and similar to baseline readings. The construction dust monitoring data are presented in Appendix F, and the monitoring locations are shown in Figure 3-1.

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4.7 Archaeological Observations The AECOM and HME field team did not observe indications of human burials, human remains, cultural items, suspected cultural items, or historic properties, as identified by the National Historic Preservation Act, at any time during construction activities.

4.8 Health and Safety No significant health and safety incidents occurred during field activities. The field team utilized the morning safety tailgate meeting to review hazards and changing conditions throughout the day. A copy of each day’s safety tailgate meeting is included in the DFRs (Appendix B).

4.9 Best Management Practices Best management practices (BMPs) were implemented throughout construction to reduce project risks and increase the likelihood of successful project implementation. The following BMPs, although not a comprehensive list, were implemented during construction: • Placement of small batches (up to 12 cy) of material in shallow lifts (equal to or less than 1-foot increments) in a slow and controlled manner. • Clam-shell or debris removal equipment was operated at a rate of no more than 1 foot per second when raising or lowering through the water column to reduce the potential for spillage and disturbance of riverbed sediments. • Daily equipment maintenance to avoid spills and leaks. • Daily safety meetings at the start of each day with all parties involved. • Containment placed around all material re-handling operations. • Utilized drip pans to prevent in-water and upland spillage of fuels and oils. • All truck loads were covered before departure to landfill. • Barge scuppers on haul barges were sealed off and utilized watertight fences to prevent water or sediment from draining off the haul barge. • Barges were not overfilled. • No grounding of construction barges was allowed. • No spudding was conducted within the cap footprint. • Increased turbidity monitoring (hourly) instead of the required 2-hour frequency to look for early warning indicators of potential problems.

4.10 Sustainable Remedial Practices Green/sustainable construction practices and strategies were utilized when possible during remediation activities and related office work. A list of green/sustainable practices implemented during the project is provided below. • The sand used for the isolation sand layer was sourced from a Columbia River deepening dredging project (beneficial reuse). • Low-sulfur or ultra-low-sulfur diesel fuel was utilized in construction equipment. • The turbidity monitoring stations were powered by solar panels.

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• Equipment inspections and maintenance were conducted daily to minimize downtime, prevent leaks/spills, and reduce additional mobilization related to equipment repair. • Equipment was shut off instead of idling when possible to reduce run time and emissions. • The field crew carpooled when possible. Out-of-town field staff stayed at a hotel within walking distance of the marina where the support boat was moored, reducing the need for an additional vehicle. • Graphics and documents were reviewed and edited electronically, reducing the amount of paper waste.

4.11 Utilities and Easements As described in Section 1.1, Site Conditions, several utilities and associated easements are present within the southern portion of the Study Area. At no time were any invasive activities, including anchoring or spudding of the barges or placement of fill material, conducted within the utility easements.

4.12 Survey Control Positioning and station control was critical for debris removal activities, cap placement activities, and environmental monitoring activities. Surveying was completed by a surveyor or hydrographer licensed in the State of Oregon. Positioning was determined using real-time kinematic global positioning system (RTK-GPS) survey control. Manual or automatic electronic tide recording systems and inertial vessel orientation/alignment systems were also utilized. HME was responsible for maintaining survey control through the project. Surveys were tied to two control points: one located on the riverbank at the northern extents of the RM 13.5 Study Area, and another at an existing City of Portland benchmark at the southern extent of the Study Area. The control points were used for the in-water bathymetric surveys and the topographical surveys so that the data files were tied to a common control point. The location and coordinates for both control points are provided in Appendix C (Sheet F02). All survey data were reported in the following datums: • Horizontal Station Control - The horizontal survey data were tied to the North American Datum of 1983 (NAD 83) State Plane Coordinate System (SPCS) Oregon North, in feet. • Vertical Elevation Control - The vertical survey data were tied to NAVD 88, in feet. The multi-beam survey equipment had a vertical accuracy of 0.1 foot; horizontal accuracy was sub-meter.

4-11 SECTIONFIVE Long-Term Monitoring

5.0 LONG-TERM MONITORING Long-term monitoring and maintenance will be conducted to confirm remedy protectiveness and compliance with RAOs over time by confirming that the cap remains stable and does not erode over time. Monitoring will be conducted in accordance with the Final RM 13.5 Cap Inspection Monitoring and Maintenance Plan (Appendix E of the RD Report); the monitoring plan will be updated with the final as- built bathymetric survey data, for comparison against future monitoring data. A 6-month post-construction survey is scheduled to occur during the seasonal high water period in April 2016. Following the completion of the 6-month post-construction survey, long-term cap monitoring will commence; cap monitoring events will be conducted during project Year 1 (2017), Year 3 (2019), Year 5 (2021), and Year 10 (2026). Following the 2026 survey, additional periodic bathymetric surveys will be conducted every 10 years or as determined necessary by DEQ based on the results of previous surveys. Cap monitoring will also be performed following the occurrence of a 100-year flood event or after a significant local seismic event. The 100-year flood event in the lower Willamette River is defined as a river stage of 32.2 feet NAVD 88 (30.1 feet City of Portland Datum [COPD]) or a river discharge of 375,000 cubic feet per second (URS 2014). A significant local seismic event is defined as an earthquake in excess of magnitude 6. DEQ or PGE may also recommend an additional inspection monitoring event after the occurrence or notification of an unforeseen significant disturbance event that the cap was not designed to withstand (e.g., grounding of a vessel).

5-1 SECTIONSIX Certification Statement

6.0 CERTIFICATION STATEMENT The construction oversight and project engineering services described in this report were performed by AECOM on behalf of PGE for construction activities related to the PGE RM 13.5 sediment isolation cap construction. Based on the observations made during construction, material testing results, and the final product constructed on-site, it is the opinion of AECOM that the sediment isolation cap was constructed consistent with standard trade practices, is in substantial compliance with the RD Report and engineering plans and specifications, and is consistent with the design intent as approved by the DEQ. This includes compliance with permit conditions (unless otherwise noted above). A Letter of Certification from HME, the construction contractor, is provided in Appendix P.

6-1 SECTIONSEVEN References

7.0 REFERENCES AECOM. 2015. Final Remedial Design Report, River Mile 13.5 Sediment Study Area. September 2015. DEQ (Oregon Department of Environmental Quality). 2009. Downtown Portland – Willamette River Sediment Evaluation – Preliminary Identification of Locations of Interest. Oregon Department of Environmental Quality, October 13. DEQ. 2012. Letter from Tom Gainer, Oregon Department of Environmental Quality to Richard George, PGE, Regarding Order on Consent for PGE Willamette Project, ECSI #5249. DEQ No. LQVC- NWR-12-07 Order on Consent for Feasibility Study and Source Control Measures. July 16, 2012. DEQ. 2015. Record of Decision, Selected Remedy for the PGE Willamette River Sediment Sites, Portland, Oregon. April 2015. URS. 2011. Final Sediment Remedial Investigation Report River Miles 13.1 and 13.5, Willamette River, Portland, Oregon. Prepared for Portland General Electric Company of Portland, Oregon by URS, for submittal to Oregon DEQ. December 2011. URS. 2014. Final Feasibility Study for River Miles 13.1 and 13.5, Willamette River, Portland, Oregon. Prepared for Portland General Electric Company by URS. November14, 2014. USEPA (U.S. Environmental Protection Agency). 2005. Contaminated Sediment Remediation Guidance for Hazardous Waste Sites. Website: http://www.epa.gov/superfund/health/conmedia/sediment/guidance.htm.

7-1 Tables

TABLES Table 1-1 RM 13.5 Feasibility Study SWAC Analysis Table 1-2 RM 13.5 Remedial Action Objectives and Remedial Goals Table 4-1 Sediment Isolation Cap Chronology Table 4-2 Fill Material Volume Summary Table 4-3 Environmental Monitoring Summary

Table 1-1. RM 13.5 FS SWAC Analysis Portland General Electric

SWACs

Total Study Total PCBs as Remedial Alternative Dioxin/Furan Total DDx Area (SF) Aroclors RM TEQ Mammals (ug/kg) (ug/kg) (ng/kg)

Mean Upriver Background Concentrationa 5.4 0.72 1.43

Baseline SWAC (pre-construction) 94,852 50.6 3.22 4.89 13.5 Alternative 2 Isolation Capb (post- 94,852 5.47 0.86 1.16 construction time 0)

Notes: BOLD = SWAC exceeds Mean Upriver Background Concentration a Background concentrations for contaminants in sediment (in dry weight) from the Portland Harbor RI/FS, Draft Feasibility Study, March 30, 2012. These are the screening criteria for RM 13.5.

bClean up area footprint is 1.1 acres for the required isolation cap.

DDx = Sum of DDD, DDE, DDT FS = feasibility study kg = kilogram Mean = Kaplan-Meier mean concentration ng = nanogram PCB = polychlorinated biphenyls RM = river mile SF = square feet SWAC = surface weighted average concentration TEQ = toxic equivalent ug = microgram

River Mile 13.5 Sediment Isolation Cap Construction Completion Report Table 1-1 1 of 1 Table 1-2. RM 13.5 Remedial Action Objectives and Remedial Goals Portland General Electric

Remedial Action Objectives (RAOs) Remedial Goals

Prevent unacceptable exposures of contaminants of potential concern (COPCs) Surface weighted average concentration (SWACs) (immediately post-remediation) calculated for the river 1 and constituents of potential ecological concern mile (RM) 13.5 Study Area should be below the mean upriver surface sediment background concentrations (CPECs) in surface sediment to human health for indicator chemicals. and ecological receptors.

During remedy implementation, water quality monitoring, upstream, in the work-zone and downstream of the Project Area. The water quality would be compared to established Oregon Department of Environmental Reduce migration of the COPCs and CPECs in Quality (DEQ) surface water concentrations presented in the 2005 Joint Source Control Strategy document 2 the sediment to the water column or to other and/or compliance criteria developed in the Final Remedial Design. In addition, chemical isolation modeling areas of the river. was conducted to evaluate the long-term effectiveness at reducing migration of chemicals in the underlying sediment through the overlying cap thicknesses and results were used to determine final cap design thicknesses.

The area of each remedial alternative considers the established screening criteria, which are based on HSCs and background UPLs. Reduction of the concentration in the surface sediment was evaluated by calculating Treat areas identified as sediment remediation SWACs. The resulting SWACs (post-remediation time 0) were calculated for RM 13.5 Study Area and the areas, with concentrations above the screening resulting SWACs were compared quantitatively to human health and ecological criteria, including the mean criteria, which are based on hot spot upriver surface sediment background concentrations for contaminants in sediment (consistent with the concentrations (HSCs) and background upper 3 Portland Harbor Draft Feasibility Study dated March 30, 2012, or most recent level consistent with the prediction limits (UPLs) to the maximum extent Portland Harbor). To evaluate the volume reduction for each remedial alternative, the volume of the treated practical by reducing concentration, volume, surface sediment was calculated for each remedial alternative. The volume of the subsurface sediment and/or mobility to reduce the risk associated removed from each Study Area was also calculated to evaluate the effectiveness of each remedial action with these areas. considered at treating areas of impacted surface and subsurface sediment. The reduction of mobility was evaluated qualitatively in the FS.

Support green remediation initiatives and best management practices to minimize the volume Qualitative evaluation criteria are used to evaluate the RAO in the FS, including utilizing green remediation of generated waste requiring disposal and best management practices, and considering Oregon’s Recycle Laws and DEQ’s green remediation policy, 4 reduce the toxicity of all waste requiring finalized in November 2001, that promote and support implementing sustainable practices that recognized disposal and reduce the toxicity of all waste the environmental benefits of waste prevention, reuse, and recycling. Sand cap material was beneficially re- generated during remedy implementation to the used for dredged material. maximum extent practicable.

River Mile 13.5 Sediment Isolation Cap Construction Completion Report Table 1-2 1 of 2 Remedial Action Objectives (RAOs) Remedial Goals

During remedy implementation, Occupational Safety and Health Administration Hazardous Waste Operations Protect worker health and safety, and minimize and Emergency Response Standard requirements are used to define chemical-specific concentrations for 5 short-term implementation risks during worker exposure. Additional protection of worker health and safety are also specified in a remedy-specific implementation of the remedy. health and safety plan.

Notes: 1. RAOs and Remedial Goals were taken from Final Feasibility Study for River Miles 13.1 and 13.5, Willamette River, Portland, Oregon. Prepared for Portland General Electric Company by URS. November 14, 2014.

River Mile 13.5 Sediment Isolation Cap Construction Completion Report Table 1-2 2 of 2 Table 4-1. RM 13.5 Sediment Isolation Cap Chronology Portland General Electric

Project Phase Construction Activity Dates (2015)

DEQ Approval of Final Remedial Design Report September 9 Placement of Turbidity Meters September 15 Equipment Mobilization September 16 Baseline Turbidity Monitoring September 16 - 17 Pre-Construction Baseline Dust Monitoring September 17 - 18 Phase Pre-Construction Field Test (Turbidity Meters) September 18 Debris Removal September 18 - 24 Baseline Noise Monitoring September 22 - 23 Post-Debris Removal Bathymetric Survey September 23 Debris Sample Collection October 6 Debris Disposal November 4 - 6 Environmental Monitoring September 24 - October 29 Placement of First 1-foot Sand Lift September 24 - 25 1-foot Lift Confirmation Cores Collected September 28 Placement of Second 1-foot Sand Lift September 28 - 29 Single-Beam Bathymetric Survey September 29 Second 1-foot Lift Confirmation Cores Collected September 30 Sand Placement to Fill Low Spots September 30 - October 23 Construction Phase Armor Layer Construction October 16 - 29 Site Visit 1 with Corps October 23 Site Visit 2 with Corps October 26 Diver Inspection of Armor October 27 Final Bathymetric Survey October 29 Equipment Demobilization October 29 Turbidity Meter Removal November 2 Decontamination Water Sampling November 3 Decontamination Water Disposal January 12 (2016)

River Mile 13.5 Sediment Isolation Cap Construction Completion Report Table 4-1 1 of 1 Table 4-2. RM 13.5 Fill Material Volume Summary Portland General Electric

Material Type As-Built Volume Placed (cubic yards)

Isolation Sand Layer Material 8,829 Shoreline Armor Material 1,812 Cap Armor Material 614 Toe Armor Material 364 Project Total 11,619

Notes: 1. All materials were obtained from Knife River Materials, Waterview Pit. 2. The isolation sand layer material was beneficially re-used from the Columbia River channel deepening project near Longview, WA, and consisted of a course sand material. 3. The shoreline armor consisted of a roughly 1-2 inch angular stone, placed in areas above an elevation of +3 feet (North American Vertical Datum 88). 4. The cap armor consisted of a roughly 3/4 - 2 -inch rounded stone, placed over the majority of the isolation sand layer. 5. The toe armor consisted of a roughly 1-3 inch rounded stone, placed along the upstream, downstream, and outer edges of the cap.

River Mile 13.5 Sediment Isolation Cap Construction Completion Report Table 4-2 1 of 1 Table 4-3. RM 13.5 Environmental Monitoring Summary Portland General Electric

Number of Number of Number of Number of Days Monitoring Monitoring Type Readings Minimum Value Maximum Value Criteria Compliance Monitoreda Frequency Collecteda Exceedances Exceedances

Daily During In- Turbidity Monitoring 28 528 1.04 NTUs 10.82 NTUs 5b 0 Water Work

Weekly During Noise Monitoring 7 11 61 dB 65.9 dB 0 0 Construction

Weekly During Dust Monitoring 6 50 0.001 mg/m3 0.057 mg/m3 0 0 Construction

Notes: aIncludes baseline and environmental monitoring. Environmental monitoring was conducted from September 24 through October 29, 2015. bCriteria exceedances were not considered compliance exceedances if downstream turbidity levels returned to < 5NTUs below the upstream monitoring levels (background) by the next second 2-hour compliance monitoring event. 1. Turbidity Monitoring Criteria = 5 NTU increase above the upstream monitoring levels (background). 2. Noise Perimeter Criteria = 70dB, per Multnomah County commercial and industrial noise limits. 3. Perimeter Dust Criteria = 3 mg/m3.

dB = decibels mg/m3 = milligrams per cubic meter of air of respirable particulates NTUs = nephelometric turbidity units

River Mile 13.5 Sediment Isolation Cap Construction Completion Report Table 4-3 1 of 1 Figures

FIGURES Figure 1-1 Site Location Map Figure 2-1 Proposed Sediment Isolation Cap Extent Figure 3-1 Environmental Monitoring Locations Figure 3-2 Post Debris Removal Elevation (Pre-cap) Figure 4-1 Placement Grid Cell Layout Figure 4-2 Isolation Sand Layer Placement Pictures Figure 4-3 Final Isolation Sand Layer Thickness Figure 4-4 Final As-Built Sand Isolation Layer Slope Figure 4-5 Armor Layer Placement Pictures Figure 4-6 Final Armor Layer Thickness Figure 4-7 Final As-Built Armor Layer Slope Figure 4-8 Final Bathymetry Contours (Post-capping) and Shoreline Habitat Shelf

Legend

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-30 -15 Contour (5ft NAVD88) Contour (1ft NAVD88) Isolation Cap Extent Grade of Isolation Sand Layer ≥ 3:1 (69%) <3:1 thru 2.9:1 (6%) <2.9:1 thru 2.8:1 (5%)

N < 2.8:1 thru 2.7:1 (4%) « <2.7:1 thru 2.6:1 (3%) Notes: Feet 1. Elevation data from several multibeam, single beam, and <2.6:1 thru 2.5:1 (2%) topographic surveys conducted by SolmarHydro and HME in October 2015. 0 25 50 100 < 2.5:1 (11%) PGE RM 13.5Sediment Isolation Cap Completion Report Portland, OR ProjectNo.: 60439278 Date: 2016-04-26 P:\ENV\PROJECTSW\PGE\RM 13.5Construction Oversight\900 GIS - CAD\GIS\MXDs\Report Figures\Figure 4-4_FinalSandCapSlope.mxd P:\ENV\PROJECTSW\PGE\RM 13.5 Construction Oversight\900 GIS - CAD\GIS\MXDs\Report Figures\Figure 4-5_Armor Layer Placement Pictures.mxd Armor Stone Hand Grading Hand Stone Armor Armor Placement Overview Placement Armor Armor Stone Placement Shoreline Placement Along Stone Armor Shoreline Habitat Shelf Shelf Area Habitat Shoreline

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PGE RM 13.5 Sediment Isolation Cap Completion Report Portland, OR Final Armor Layer Thickness Project No.: 60439278 Date: 2016-04-26 Figure: 4-6 P:\ENV\PROJECTSW\PGE\RM 13.5 Construction Oversight\900 GIS - CAD\GIS\MXDs\Report Figures\Figure 4-7_FinalArmorCapSlope.mxd 0 « N 25 50 100 Feet topographic surveys conducted by SolmarHydro and HME in October 2015. October in HME and SolmarHydro by conducted surveys topographic and beam, single multibeam, several from data Elevation 1. Notes: Grade of Final Cap and Armor Layer and Armor Cap Final of Grade Legend < 2.5:1 (15%) <2.5:1 (3%) 2.5:1 thru <2.6:1 (4%) 2.6:1 thru <2.7:1 (4%) 2.7:1 thru <2.8:1 (4%) 2.8:1 thru <2.9:1 (4%) 2.9:1 thru <3:1 (66%) 3:1 ≥ and Cap Final Extent Armor NAVD88) Contour (1ft NAVD88) Contour (5ft

PGE RM 13.5 Sediment Isolation Cap Completion Report Portland, OR Final As-Built Armor Layer Slope Project No.: 60439278 Date: 2016-04-26 Figure: 4-7 Figure: 4-8

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APPENDICES

Appendix A Permits Appendix B Daily Field Reports Appendix C As-Built Drawings Appendix D Turbidity Monitoring Data Appendix E Noise Monitoring Data Appendix F Dust Monitoring Data Appendix G Debris Disposal Data Appendix H Post Debris Removal Survey Data Appendix I DEQ Correspondence Appendix J Armor Stone Gradation Results Appendix K Response to DEQ’s Comments on the RM 13.5 Installed Armor Stone Size Appendix L Sediment Core Information Appendix M Final Sand Layer Survey Data Appendix N Final Armor Layer Survey Data Appendix O Wash Water Analytical and Disposal Appendix P HME Letter of Certification