Willamette River, Portland, OR

A.83 Willamette River, Portland, OR

A.83.1 Contacts

Regulatory Contact:

Scott Manzano
Oregon Department of Environmental Quality
503-229-6748

Site Contact:

Paul Fishman
SWCA Environmental Consultants
434 NW Sixth Avenue, Suite 304
Portland, OR 97209
503-224-0333 X-320 (W)
503-789-5107 (Mobile)

A.83.2 Summary

Environment:	River
Scale:	Full
Contaminants of Concern:	PCBs, metals, PAHs, TBT
Source Control Achieved Prior to Remedy Selection?	Source control, dredging, sand/rock capA covering over material (contaminated sediment) used to isolate the contaminants from the surrounding environment., MNR
Final Remedy:	Shoreline removal, in-water cappingTechnology which covers contaminated sediment with material to isolate the contaminants from the surrounding environment.

A.83.3 Site Description

The Zidell waterfront property consists of 32.17 acres in Section 10, Township 1 South, Range 1 East of the Willamette Meridian. The site is located at 3121 SW Moody Avenue in Portland, Multnomah County, Oregon. The property is bordered by SW Moody Avenue on the west, by property zoned for commercial use on the north (currently vacant property owned by the Oregon Health Sciences University [OHSU]), and by the former Pacific Metals facility on the south currently under redevelopment. The site is bordered to the east by the Willamette River between river miles 13 and 15. Zidell Marine Corporation and Zidell both operate on the site, which varies from 70 ft to 850 ft wide (east to west), and is 3,300 ft long (north to south).

Historically, the site was used for building, dismantling, converting, repairing, and salvaging ships and barges. It was also used for scrap metal operations, wire burning and aluminum smelting, and housing construction. The south part of the site is currently used for barge construction, and the north part is vacant or used to store salvage materials.

The primary source of contamination at the site is the long history of ship dismantling activities and barge construction.

CSM summary: The primary source of sediment contamination appears to be related to past ship dismantling activities and fires along the dock. Organotin contamination is most likely associated with paint chips produced by sand blasting. The source of metals is most likely sand-blasting grit, paint chips (chromium, copper, and lead), and other parts of the ships. PCBs may have been contained in cables, gaskets, paint, and elsewhere in older ships, as well as in transformers dismantled at the site. The PAHs and petroleum hydrocarbons may have been generated during ship and tank dismantling as well as during dock fires. The source of COIs may also be particulates suspended in stormwater discharged to the Willamette River through stormwater outfalls, surface soils eroded from the upland portion or bank of the site, historical groundwater discharges to the Willamette River, and suspended sediment transported from upriver sources. Many factors influence the transport, fate, and bioavailabilityThe relationship between external (or applied) dose and internal (or resulting) dose of the chemical(s) being considered for an effect (NRC 2003). of chemicals in sediments and their partitioning into pore waterWater located in the interstitial compartment (between solid-phase particles) of bulk sediment., including the type of chemical (nonpolar hydrophobic organic compounds and metals), the chemistry of the environment (oxic versus anoxic, marine versus freshwater), physical conditions (grain size, disturbance, and stability of the sediments), the amount and source of organic carbon in sediments (humic material, coal, soot, oil), the pHA measure of the acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions, increasing with increasing alkalinity and decreasing with increasing acidity. The pH scale commonly in use ranges from 0 to 14. and concentration of ammonia in pore water, and the presence of metal sulfides in sediment.

A.83.4 Remedial Objectives

Site risks: Upland portions of the site pose an unacceptable risk to future residents and current and future excavation and construction workers. Existing sediment contamination within 200 ft of the shoreline poses an unacceptable risk to recreational anglers through the fish ingestion pathway.

Upland portions of the site pose an unacceptable risk to ecological receptors including terrestrial species, birds, plants and invertebrates. Existing sediment contamination within the Willamette River and along the shoreline of the site poses an unacceptable risk to sediment dwelling organisms and other ecological receptors (such as birds and mammals) through food web exposures.

RAO(s)/Project objectives:

Medium RAOs:

Prevent future residents and worker exposure to soil containing constituents exceeding acceptable risk-based concentration (RBC) values.
Prevent ecological receptors from exposure to soil containing CPECs exceeding DEQ SLVs.
Prevent transport of COCs/CECs in soil to the Willamette River through stabilization of shoreline and stormwater runoff controls.
Remediate soil hot spots to the extent feasible.
Protect humans against exposure to site-related COCs above protective levels.
Minimize transport of sediment containing COCs and CECs above cleanup levels to downstream areas of the river.
Ensure sediments contaminated with CECs above protective levels do not become accessible to benthic organisms, or aquatic and terrestrial organisms through food chain exposure.
Remediate hot spots of contamination in sediment by reducing their concentration, volume, or mobility to the extent feasible and practical.
Protect ecological habitat and beneficial uses of surface water adjacent to the facility.

A.83.5 Remedial Approach

Final selected remedy: Removal/dredging and capping, MNR

The selected remedial action for contaminated soil consists of the following elements:

Interim source controlThose efforts that are taken to eliminate or reduce, to the extent practicable, the release of COCs from direct and indirect ongoing sources to the aquatic system being evaluated. measures to prevent releases of hazardous substances to the Willamette River from upland and bank soils through stormwater runoff.
Excavation and off-site disposal of up to 8,000 yd³ of contaminated soil exceeding hot spot concentrations, and asbestos containing material.
On-site consolidation of soil exceeding cleanup levels from Greenway Area or future public right-of-ways to non-Greenway area of the site prior to capping.
Re-grading the Greenway shoreline to facilitate placement of a soil cap above an elevation of 13 ft and upgrading existing armoring of the riverbank from 13 ft to the Willamette River sediment surface to minimize future releases of hazardous substances in soil to the Willamette River.
Engineering controls involving placement of a cap over residual soil contamination exceeding risk-based concentrations.
Institutional controls involving inspection and maintenance of the soil cap and protocols for future sub-surface maintenance activities.

The selected remedial action for contaminated sediments consists of the following elements:

Engineering controls to include placement of a clean sand/rock cap over up to 17 acres of contaminated sediment along the Zidell shoreline.
Institutional controls involving inspection and maintenance of the sediment cap.
Periodic reviews by DEQ.
Selective sediment dredging/capping of the barge launchway to facilitate continued site operations or possible future use of the area for public access for river-related activities.
The sediment remedy also includes MNR for sediment outside the cap.

Why was the remedy selected? A total of seven alternatives were considered for soil and five alternatives were considered for sediment. Selected remedy was based on consideration of long and short-term effectiveness, feasibility, reliability, and cost.

A.83.6 Monitoring

Monitoring elements: Controls were placed in the river to reduce turbidity generated during capping. Capping methods were selected to limit disturbance of underlying sediment. Divers were used to collect samples from the cap after initial placement. Sampling after cap is placed will occur to document that contaminated material was not displaced during capping and to provide a baseline for MNR monitoring.

RAOs/project objectives achieved? Remedy implementation in progress.

A.83.7 Advantages and Limitations

Site Specific Challenges:

Regulatory—Lengthy discussions and revised proposals due to cap placement permitting. Armoring material was ultimately covered with rock determined to be fish friendly.
Technical—Coordination with bridge construction that overlapped with cap area was required.

A.83.8 References

Oregon Department of Environmental Quality - Zidell Waterfront Property. http://www.deq.state.or.us/lq/cu/nwr/zidell/index.htm.

Publication Date: August 2014

Permission is granted to refer to or quote from this publication with the customary acknowledgment of the source (see suggested citation and disclaimer).