Sediment is a naturally occurring material that is broken down by processes of weathering and erosion and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone (sedimentary rocks) through lithification.
The natural flow of water commonly causes the need for regular dredging of local waterways. Other than mining, the most common use for a dredge is reservoir dredging. Some cities and municipalities source the community’s water from open-air reservoirs. Sometimes, these reservoirs silt in or become contaminated with the material. Dredging is an efficient and effective way to keep these reserves clean.
Sediments are most often transported by water (fluvial processes) and wind (aeolian processes), and glaciers. Beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert dunes and loess are examples of aeolian transport and deposition. Glacial moraine deposits and till are ice-transported sediments.
Some of Our Cleanup Remedies and Technologies :
- In situ treatment commonly involves adding treatment amendments to accelerate contaminant removal and/or immobilize the contaminant. Amendments that have been considered for sediment treatment include organophilic clay, zeolites, bauxite, iron oxide/hydroxide, apatite, and zero-valent iron. However, the most common approach is activated carbon (AC) as a thin-layer cap or incorporated into the sediment.
- Monitored natrual recovery takes advantage of natural processes, including natural burial of contaminated sediments with clean sediments.
- Capping involves the placement of clean material over the contaminated sediments. When contaminants are relatively immobile in sediment, a cap prevents flora and fauna from contacting them. A relatively impermeable cap can prevent groundwater from discharging through the contaminated sediment. The cap thereby diverts the groundwater away from the contaminated area.
- Dredging or Excavation removes contaminated sediment from a water body without draining or diverting the water. Dredging also removes a certain amount of water with the sediment. The sediments are usually dewatered on land, and the water is usually treated before discharge back to the water body or public treatment works. The contaminated sediment is then disposed of in a landfill or a confined disposal facility. Highly contaminated sediment may be treated before disposal.
Risk Management and Remedy Planning Solutions
- Strategic and technical planning
- Regulatory/Stakeholder group assistance
- Empirical and numerical modeling
- Ecological and human health risk assessments
- Bench and pilot-scale studies
- Integrated shoreline development and contaminated sediment management
- Remedial alternatives analysis
- Sediment remediation design
- Remediation Engineering Services
- Phase I / Site Assessment Services
- Risk Assessment & Toxicology Services
- Visual presentations of proposed remedy, and technical and risk communications
- Permit acquisition
- Construction management/turnkey solutions
- Site restoration
- Remedy performance monitoring
- Natural Resource Damage assessment assistance