Case studies presented in this appendix provide an overview of the capping sites that are focused on the chemical isolation of contaminated sediments. Table A-1 presents a list of the case studies summarized in this appendix, which typically include the following information:
- site description
- site investigation and CSM summary
- remedy design and construction
- post-remedy monitoring
- references
- photos
Table A-1. Case study summary
| No. | Site Description | Location | COCs | Remedy Description | References |
| 1 | Crude Oil Spill Site | Mayflower, Arkansas | Crude oil–related sheens | Excavation and backfilling, reactive capping, and in situ amendment placement | (Arcadis 2014a, 2014b, 2015, 2017) |
| 2 | Former Portland Gas Manufacturing Site | Portland, Oregon | Oily or tar-like materials, PAHs, TPH, BTEX, cyanide, metals | Dredging, amended capping, enhanced natural recovery, and monitored natural recovery | (Anchor QEA 2019, 2020, 2021; Oregon Department of Environmental Quality 2017) |
| 3 | Diamond Alkali Superfund Site, Lower 8.3 Miles of the Lower Passaic River | Essex and Hudson Counties, New Jersey | Dioxins/furans, PCBs, mercury, total(4,4′)DDx, copper, dieldrin, PAHs, lead | Determination of site-specific cap material, porewater and sediment-porewater partition coefficients | (Arcadis 2021; Arcadis and Tech 2020) |
| 4 | East Branch Grand Calumet River | Calumet, Indiana | PAHs and metals | Dredging and reactive cap | (J.H. Hull et al. 2015) |
| 5 | Zidell Waterfront Property | Portland, Oregon | PCBs, metals, PAHs | Cap over riverbank and sediment bed | (Oregon Department of Environmental Quality 2023) |
| 6 | Linnton Terminal | Portland, Oregon | LNAPL | Multilayer cap | (Gentry et al. 2020) |
| 7 | Manistique River and Harbor | Manistique, Michigan | PCBs | Removal and disposal and amended cover placement with activated carbon | (EA and Foth 2013), (Arcadis of Michigan 2018, 2020), (Riley 2021) |
Acronyms and Abbreviations:
BTEX = benzene, toluene, ethylbenzene, and xylene
COC = contaminant of concern
LNAPL = light nonaqueous-phase liquid
PAH = polycyclic aromatic hydrocarbon
PCB = polychlorinated biphenyl
TPH = total petroleum hydrocarbons
