Table 1. Summary of Site Characterization Needs for Contaminated Sediment

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6 years ago

Table 1. Summary of Site Characterization Needs for Contaminated Sediment
Data Type	Potential Site characterization Approach		Implication for remedy selection	Tools involved
Physical characteristic
Sediment stability	Require to perform tests including bathymetric survey, grain size analysis, bed pins, scour chains, geochronology cores.		Stable sediments require less erosion protection for capping options, conductive to monitored natural recovery if cleaner material is being deposited	Sedflume measurement; sediment trap; bathymetric survey
Sediment deposition rate	Sediment deposition rates may be estimated using sediment trap and geochronology cores. Requiring dredge record, historical bathymetry survey, sediment dating		Monitored natural recovery requires deposition of clean material over contaminated material	sediment trap; core sampler
Erosion potential of bedded sediments	Estimated using combined Sedflume measurement, flow measurement, and hydrodynamic evaluations		Contaminated sediment with high resuspension potential may represent source of downstream and water column contamination	flow(hydrodynamic) measurement device;
Water depth and site bathymetry	Bathymetric features including water depth estimation; it helps delineation of contaminant extent		Important for removal method selection	water measurement device
In-water and shoreline infrastructure	Physical and geophysical site survey for identifying location of structure		The presence of structure has impact on feasibility of various sediment remediation options
Presence of hard bottom	Hard bottom (bedrock, hard pan, coarse sediment, large cobbles, boulders) maybe identified		The presence of hard bottom may limit the effectiveness of dredging.	sediment core (for hard bottom); geophysical survey
Presence of debris	Debris survey performed in urban waterway should include geophysical survey, diver survey		The presence of debris has significant impact on feasibility and effectiveness of removal based sediment remedies	side scan sonar; sub bottom profiler; underwater photograph; metal detector
Hydrodynamics	The evaluation should include assessment of wave action, tidal force, wind-driven seiche potential		Hydrodynamics have direct bearing on the evaluation of contaminant mobility, and therefore capping-based remedies and MNR remedies	doppler profile; water stage data;
Groundwater/ surface water interaction	Evaluation of the potential of groundwater movement to transport subsurface sediment and groundwater contaminant to surface sediment layer and water column.		Useful for understanding groundwater source control, contaminant fate and transport, and bioavailability. Areas with high advective groundwater flux may limit the effectiveness of sediment remedies.	water level log; Piezometer; Geochemical measurement
Sediment and pore-water geochemistry (TOC, DOC, POC)	Characterizing sediment and pore water for a range of constituents may be useful for understanding contaminant fate and transport processes, biodegradation and contaminant bioavailability.		Useful for evaluation of MNR, in-situ treatment and capping technologies
Sediment characteristics
Geotechnical properties	including bulk density, shear strength, specific gravity, water content, cohesiveness, organic content, Atterberg limits		Geotechnical parameters have direct effect on feasibility of all remedial technologies; also useful in evaluation of dewaterability of dredged sediment	core sampler;
Potential for resuspension/ residual	Elutriate testing such as dredged residual elutriate test (DRET) can inform assessment of short term water quality impacts		Data maybe used to evaluate releases during dredging and to estimate potential short term and long term impact
Sediment consolidation (pore-water extraction)	Provide engineering properties needed to calculate settlement or pore-water extraction, followed by chemical testing		Influence extent to which dissolved contaminant may move into cap during placement and settling.
Benthic community structure and bioturbation potential	Characterization of benthic community through diversity and abundance survey may be performed to determine habitat characteristics		The presence of a healthy benthic community should be considered when evaluating invasive sediment remedies such as dredging	core sampler; benthic sampler
Contaminant transformation of degradation	Literature surveys should be performed to develop an initial understanding of the potential for contaminant transformation and degradation.		Support capping models and evaluate MNR （Monitored natural recovery ）
Source identification and control	Develop CSM that considers sources of contaminants; identify regulatory program and framework in place to control sources of contaminant		Effective source control is a critical components of all successful sediment remedies
Ebullition	identify areas with significant ebullition		Affect contaminant mobility and transport and may impede capping success
Background	Characterization of natural and anthropogenic background is critical for bioaccumulative chemicals such as PCBs; testing may be bulk sediment, surface water, biota tissue, and pore water		characterization of background is critical to the evaluation of MNR and the establishment of achievable site cleanup levels and effectiveness of any remedial technology’
Contaminant characteristics
Horizontal and vertical distribution of contamination		The area and volume of sediment contamination that is useful for identifying area of diffuse, widespread, low level contamination and localized area of high concentration	Critical element for evaluation of all sediment remedial technologies.	XRF for metals; UVF for PAH; Immunoassay(PCB, PAH, pesticide, dioxin)
Contaminant type (Inorganic, UXO, size fraction)		Most contaminant are associated with the fine-grained sediment fraction (silt and clay), some contaminant area sand-sized and larger (lead shot, UXO)	Direct effect on risk and exporesure potential as well as removal strategies
Contaminant concentration		Bulk sediment, surface water, pore-water, and biota tissue may be analyzed to determine contaminant concentration distribution and bioavailability	Critical element for evaluation of all sediment remedial technologies.
Exposure pathway		Exposure pathway contributing to risk at the site and the degree of risk throughout the site	Direct impact on the RAOs and evaluation of remedial technologies
Presence of source material (NAPL)		Sediment core should be evaluated to determine presence/absence of NAPL	Direct effect on releases during dredging and the effectiveness of capping, MNR.	sediment core sampler
Contaminant mobility		NAPL and soluble contaminants should be identified	Critical element for evaluation of all sediment remedial technologies.
Contaminant bioavailability and toxicity		Measures needed to fully assess risk at sediment sites	Critical element for assessing risk and developing site cleanup level and to identify areas that may contribute disproportionately to potential site risk	Bioassay for toxicity;
Contaminant transformation of degradation		Literature surveys should be performed to develop an initial understanding of the potential for contaminant transformation and degradation.	Support capping models and evaluate MNR
Source identification and control		Develop CSM that considers sources of contaminants; identify regulatory program and framework in place to control sources of contaminant	Effective source control is a critical components of all successful sediment remedies
Ebullition		identify areas with significant ebullition	Affect contaminant mobility and transport and may impede capping success
Background		Characterization of natural and anthropogenic background is critical for bioaccumulative chemicals such as PCBs; testing may be bulk sediment, surface water, biota tissue, and pore water	Characterization of background is critical to the evaluation of MNR and the establishment of achievable site cleanup levels and effectiveness of any remedial technology’