Hartman, E.; Kim, K.; Santiago, R.; Joyner, R.; Grahm, M.. (2014). “The use of a thin-layer cap to manage Hg and PCB Contaminated Sediments in Peninsula Harbor, Ontario, Canada..” Presentation
Keywords:Mercury, PCBs, Pulp Mill, Chlor-Alkali Plant, Capping
Summary:The slide show describes thin-layer capping for in-situ remediation of mercury and PCB contaminated sediments in Peninsula Harbor, Ontario. Engineering design, contracting, environmental mitigation measures, implementation and monitoring are covered. Descriptive photographs are included.
What You Will Find Here:Slides
Virginia Institute of Marine Sciences. (2014). “Thin-layer Sediment Addition of Dredged Material for Enhanced Marsh Resilience.“
Keywords:Thin-Layer Addition, Marsh Resilience
Summary:Virginia’s coastal marshes are valued at $25,000 per acre per year. These marshes are lost due to development and sea level rise. Thin-layer additions of dredged material to marshes could allow them to reach a desired elevation. The goal is to promote vigorous plant growth. Costs associated with the technology include: dredged material transport, possible remediation of dredged material, engineered reductions in wave impacts, environmental impact studies, and planting of seedlings. The technology also requires public ownership of tidal and subaqueous lands, which is the current Virginia policy.
What You Will Find Here:Physical-Biological Considerations p. 1, Economic Considerations p. 2, Policy and Regulation p. 3.
Cornelissen, G.; Krusa, M.E.; Breedveld, G.D.; Eek, E.; Oen, A.M.P.; Arp, H.P.H.; Raymond, C.; Samuelsson, G.; Hedman, J.E.; Stokland, O.; Gunnarsson, J.S.. (2011). “Remediation of Contaminated Marine Sediments Using Thin-Layer Capping with Activated Carbon – A Field Experiment in Trondheim Harbor, Norway.” Environ. Sci. Technol. 45, 6110-6116
Keywords:Thin-Layer Caps, Activated Carbon, PAHs, Norway
Summary:Thin-layer caps of activated carbon (AC) mixed with clay, AC alone, and AC with a sand covering were domonstrated in Norway as a remediation strategy for PAH contaminated marine sediment. The site was in 4-6 m depth water that had a tidal amplitude of 1-2 m with currents of up to 20 cm/sec. The AC slurries were made denser than surrounding water by soaking in a 10% w/w NaCl solution, and was applied using a flexible manually opperated hose. Application rates were 20 L/min. AC mixed with clay worked best for reducing contaminant flux and minimizing effects to benthic communities. Costs of AC material was about $10/m^2 and placement costs were on the same order-of-magnitude.
What You Will Find Here:Field experiment p. 6111, Results on carbon application p. 6112, Results on reduced PAH concentrations and flux p. 6113, Effects on benthic community p. 6114
Ray, G.L.. (2007). “Thin Layer Placement of Dredged Material on Coastal Wetlands: A Review of the Technical and Scientific Literature.” ERDC/EL Technical Notes Collection (ERDC/EL TN-07-1), Vicksburg, MS: U.S. Army Engineer Research and Development Center
Keywords:Thin-Layer Placement, Review
Summary:Thin-layer placement of sediment appears to be generally beneficial for combating sediment depletion, subsidence, and sea-level rise. When hydraulically dredged, liquified, and pumped through a high-pressure spray nozzle, well mixed slurries of uniform layers can be easily placed up to 100 meters from the dredging site. If tranportation costs are not an issue, sediment can be shipped by barge or pumped longer distances. Recovery of different plant species following placement varies. It is often a function of the desired elevation and substrate of the particular species. Placement depth does seem to effect individual plant species on a site specific basis. Water from a sediment slurry has been found to drain rapidly without high levels of turbidity. Oyster larvae can be prevented from settling by just 1mm layers of sediment.
What You Will Find Here:Background p. 1, Discussion p. 5
McDonough, K. M.; Murphy, P.; Olsta, J.; Zhu, Y.; Reible, D.; Lowry, G.V.. (2007). “Development and Placement of a Sorbent-amended Thin Layer Sediment Cap in the Anacostia River.” Soil and Sediment Contamination. 16, 313-322.
Keywords:Sorbent Amendments, Coke, Geotextiles, Remediation, Thin Capping
Summary:Laminated polyester fabrics (geotextiles) can be used to apply thin layer sorbant materials followed by 15 cm of sand placement. A 1100 m^2 area, 1.1 to 5.6 m deep area in the Anacostia River was used to demonstrate this technology in 2004. Flow velocities ranged from 0.003 to 0.4 m/s and plots were contained in a silt curtain during placement. The technique did not lead to significant resuspension or recontamination of the placement area, with the exception of slight elevations of naphthalene. The mats could be placed at a rate of 100 m^2/hr with a crane and divers. Overall placement costs ranged from $29-33/m^2.
What You Will Find Here:Materials and Methods p. 316, Results and Discussion p. 319
Murphy, P., Marquette, A., Reible, D., and Lowry, G.. (2006). “Predicting the Performance of Activated Carbon-, Coke-, and Soil-Amended Thin Layer Sediment Caps..” J. Environ. Eng., 132(7), 787794
Keywords:Design, Capping, Remediation, Model Development, Attenuation
Summary:This study compares the effectiveness of commercially available sorbents that can be used to amend sand caps to improve their ability to prevent contaminant migration from the sediments into the bioactive zone. Amendments evaluated include coke, activated carbon, and organic-rich soil. The properties relevant to advective-dispersive transport through porous media sorption, porosity, dispersivity, and bulk density are measured for each material, and then used as inputs to a numerical model to predict the flux of 2,4,5-polychlorinated biphenyl PCB through a sand cap amended with a thin 1.25-cm sorbent layer. Systems with and without groundwater seepage are considered.
What You Will Find Here:Design (material selection p. 789, material characterization p. 788, groundwater seepage p. 790), Capping, Remediation (PCB), Model Development (Freundlich p. 789, Flux p. 789 – sorption, porosity, dispersivity, bulk density, simulated cap performance, half-life p. 792), Attenuation p. 791
Joseph Gailani, Douglas Clarke,Timothy Welp. (2006). “Working With Nature Beneficial Use Studies.” Presentation
Keywords:Beneficial Use Case Study, Regulatory, Planning, Cost, Monitoring, Construction
Summary:Overview presentation on beneficial use methods of placement and case study discussion.
What You Will Find Here:Beneficial Use Case Study p. 12, p. 13, p. 16, Long Distance Conveyance p. 6, Regulatory p. 8, Planning p. 9, Cost p. 10, Monitoring p. 17, Thin-Layer Placement p. 23
Turner, R.E.. (2002). “Approaches to Coastal Wetland Restoration: Northern Gulf of Mexico.” Kugler Publications.
Keywords:Dredged Material, Thin-Layer Placement
Summary:The history of thin-layer placement is covered. Thin-layer placement thicknesses for revegetation are discussed. A case of a failed thin-layer placement on very soft sediments is disscussed. The ability to convert shallow open water to vegetated marsh is possible. Important planning considerations are listed. Cost comparisons relating high-pressure spray placement to bucket dredging are provided. Monitoring of thin-layer placement may involve different attributes of plant health and several different soil/sediment parameters.
What You Will Find Here:Dredged Material Wetlands p. 77, Thin-Layer Placement p. 115
Donald R. Cahoon Jr. & James H. Cowan Jr. . (1988). “Environmental impacts and regulatory policy Implications of spray disposal of dredged material in Louisiana wetlands.” Coastal Management, 16:4, 341-362, DOI: 10.1080/08920758809362067
Keywords:Wetland Loss, High-Pressure Spray, Low-Pressure, Cost, Field Demonstration, Regulatory, Monitoring
Summary:The high pressure spray nozzle can be aimed in any direction so that the spoil can be deposited discontinuously in order to completely avoid small natural drainage streams or sensitive habitats. In saline marsh, the sprayed spoil has been observed to remain mostly in place during dredging, with little or no run-off into the canal and turbidity levels in the canal were kept low because of the use of hydraulic suction. This new disposal methodology differs importantly from conventional low-pressure hydraulic dredging and the industry standard, bucket dredging, in terms of dimensions of the spoil area, spoil deposition pattern, cost of dredging, and purported environmental impacts.
What You Will Find Here:Wetland Loss p. 342, High-Pressure Spray (Solid deposition pattern p. 345), Low Pressure Spray p. 243, Cost p. 243, p. 347, p. 359, Field Demonstration (Qualitative p. 351), Spray Dredging, Regulatory (Environmental Impacts p. 348, Policy p. 349, p. 359) Monitoring p. 360
Center for Coastal Resources Management. “Completed Project: Monitoring of Thin-Layer Placement of Material Dredged from Bogues Bay Channel in Virginia..“
Summary:A thin-layer placement project on salt marshes in Virginia.
What You Will Find Here:Webpage