The effects of sediment transport on contaminant dispersal: An example from Milford Haven

McLaren, Patrick; Little, David I.

doi:10.1016/0025-326x(87)90278-5

Cited by 43 publications

(24 citation statements)

References 4 publications

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“…This observed turbidity contrast between the north-central and the southern sides of the entrance to MHW was just as would be expected from the ebb-flood flow channel separation, and as suggested by the STA (McLaren and Little 1987). It is likely that construction and dredging increased the turbidity levels in the lower and mid-reaches of MHW in 2006.…”

Section: The Important Point With Respect To Pembrokeshire Sac Is Thasupporting

confidence: 66%

“…Although also occurring naturally in MHW (e.g. Dale Roads and Pennar Flats near Llanreath), the geometry of the H2 facies was elongated upstream on the northern shelf and downstream close to the southern shoreline, closely reflecting the original STA result (McLaren and Little 1987). In the relatively coarse-grained muddy sand sediments in the mid-reaches of MHW this is consistent with winnowing of mud from mixed sediments disturbed by dredging, due to their increased roughness, to leave a sandy surface layer.…”

Section: Visual Evidence Of Physical Processesmentioning

confidence: 72%

“…The background SPM concentrations in August 2006, already four times the previous background, were from 55.9 to 61 mg/l. With one exception, the MHW entrance is not predicted by STA to be affected by sediment transport from inside the estuary (McLaren and Little, 1987). The exception is the south channel of MHW ebbing from Angle Bay to offshore West Angle Bay.…”

Section: The Important Point With Respect To Pembrokeshire Sac Is Thamentioning

confidence: 85%

“…Although representing an integration of all the transport processes and directions working on the sediment grain size distributions and sorting gradients in MHW, the STA did not assess timescales (McLaren and Little 1987). The sediment transport rates for the surficial (<2 cm) sediments implied by the contaminant trends in MHW are rather slow, integrating ebb and flood transport in the range of several months to one year over the ~30 km axial length of MHW.…”

Section: Sediment Transport Markersmentioning

confidence: 99%

“…About 60% of all dredging and construction since 1985 has taken place on flood-tide dominated STA transport paths. The resultant trapping of sediment within MHW was predicted by McLaren and Little (1987) Trailing suction hopper dredging (TSHD) is the dominant method used for dredging in MHW, and according to Hebog (2006) can lose up to 38% of the silt/clay fraction as overflow from the hopper. The dredging strategy document (MHPA, 2011) emphasised that contracts now stipulate that hoppers are not permitted to overflow, yet the standard set (overflow density of <1.07 t/m 3 ) is sufficient to allow some of the finest sediments to escape.…”

Section: Visual Evidence Of Physical Processesmentioning

confidence: 99%

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Sediment contaminant surveillance in Milford Haven Waterway

Little¹,

Bullimore

Galperin³

et al. 2015

Environ Monit Assess

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Sediment contaminants were monitored in Milford Haven Waterway (MHW) since 1978 (hydrocarbons) and 1982 (metals), with the aim of providing surveillance of environmental quality in one of the UK's busiest oil and gas ports. This aim is particularly important during and after large-scale investment in liquefied natural gas (LNG) facilities. However, methods inevitably have changed over the years, compounding the difficulties of coordinating sampling and analytical programmes.

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Section: The Important Point With Respect To Pembrokeshire Sac Is Thasupporting

confidence: 66%

Section: Visual Evidence Of Physical Processesmentioning

confidence: 72%

Section: The Important Point With Respect To Pembrokeshire Sac Is Thamentioning

confidence: 85%

Section: Sediment Transport Markersmentioning

confidence: 99%

Section: Visual Evidence Of Physical Processesmentioning

confidence: 99%

See 3 more Smart Citations

Sediment contaminant surveillance in Milford Haven Waterway

Little¹,

Bullimore

Galperin³

et al. 2015

Environ Monit Assess

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Sediment trend analysis of the hylebos waterway: Implications for liability allocations

McLaren

Beveridge

2006

Integr Envir Assess & Manag

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Sediment trend analysis (STA) is a technique that determines the net patterns of sediment movement and their dynamic behavior or stability. The data required are the complete particle size distributions obtained from bottom grab samples collected in a regular grid over the area of interest. Appendix 1 provides the particular details of how STA is undertaken. Because many contaminants are known to associate with the natural particles contained in sedimentary deposits, STA can provide additional weight-of-evidence in ecological risk assessment, remedial investigation, remediation itself, and litigation issues. The STA was applied to 242 sediment samples collected from the Hylebos Waterway, Tacoma, Washington, USA, in support of remedial action planning, contaminant source identification, and ultimately allocation of legal liability for contamination. The Waterway itself comprises a narrow shipping channel extending 3 miles from Commencement Bay (Puget Sound) where it ends in a dredged turning basin (Upper Turning Basin). A 2nd dredged turning basin (Lower Turning Basin) is located about three-quarters of the distance down its length. Both sides of the channel are home to an extensive industrial complex associated with significant contaminant releases into the water. The area was declared a Superfund Site in the early 1980s.The results of the STA showed a consistent pattern of sediment transport directed from the mouth of the Waterway to the turning basin at its head. Divided into 5 separate transport environments (TEs), the sediments within the Waterway progress from transport in Dynamic Equilibrium near the mouth, to Total Deposition (type 1) in the vicinity of the Lower Turning Basin, followed by Total Deposition (type 2) in the Upper Turning Basin. Assuming that contaminants associate preferentially with the finer, rather than the coarser, components of the grain size distributions, a probable behavior of contaminants that can be contained in the sediments is proposed for each TE. Maps showing the spatial distributions of existing contaminant data appear to conform very well to the patterns that might be expected from the STA results. This evidence was primarily used to demonstrate that potentially responsible parties (PRPs) located at the head of the Waterway could not be responsible for contaminated sediments toward its mouth. The findings, for example, effectively dismissed the assumption by the Natural Resource Damage Trustee agencies that contaminated sediments from a particular source would be as likely to migrate down the Waterway as up the Waterway. As a result, major documented sources of contamination near the mouth should be expected to bear a larger share of the total cleanup compared with sources farther toward the head. Furthermore, the STA provided explanations for apparent anomalies such as how hot spots of polychlorinated biphenyls (PCBs) could be located near a property where PCBs had never been released into the environment. If sediment gradient pattern analysis alone were used to all...

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Estuarine Bottom Sediment Transport Based on the ‘McLaren Model’: A Case Study of Huangmaohai Estuary, South China

Huanting

1999

Estuarine, Coastal and Shelf Science

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The effects of sediment transport on contaminant dispersal: An example from Milford Haven

Cited by 43 publications

References 4 publications

Sediment contaminant surveillance in Milford Haven Waterway

Sediment contaminant surveillance in Milford Haven Waterway

Sediment trend analysis of the hylebos waterway: Implications for liability allocations

Estuarine Bottom Sediment Transport Based on the ‘McLaren Model’: A Case Study of Huangmaohai Estuary, South China

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