Sediment Capping and Treatment Services
The remediation of contaminated sediments can be quite challenging. The sediments are difficult to get to; can be located in high energy systems, such as rapidly flowing streams and rivers; can be in fresh water, salt water, or brackish conditions; can be near surface or hundreds of feet below water; and can be contaminated with hard to treat viscous NAPLs and metals, as well as conventional petroleum hydrocarbons and chlorinated solvents.
USEPA guidance states unequivocally that when it comes to sediment remediation, there are no presumptive remedies. Risk reduction is the primary goal. While dredging can remove contaminant mass, it is often expensive, difficult to implement and merely relocates the risk to upland groundwater. Furthermore, numerous studies have shown that dredging frequently leads to the recontamination of the water body with potentially deleterious effects.
Sediment capping can be a long-term solution or an effective interim measure. Ideally, the cap should be easy to install, form to the underlying sediment, have high resistance to shear forces, and isolate the contaminants to limit or preclude their bioavailability.
AquaBlok is a composite particle technology that is ideal for delivering a broad range of substrates and coatings for environmental applications. Typically, the core of AquaBlok is aggregate, while the coating is bentonite, organoclay, activated carbon or other proprietary remedial reagents.
The product is ideal for the delivery of capping materials for contaminated sediments. Because it is a bulk material with high specific gravity, AquaBlok is easy to deliver through a water column and it will naturally conform to irregular surfaces. In its standard formulation, AquaBlok will hydrate and provide a very low permeability cover (hydraulic conductivity of 10-8 to 10-9 cm/sec). Moreover, AquaBlok is self-armoring and highly shear resistant, which is great for high energy environments, such as rapidly flowing streams and rivers.
Significantly, the structure will heal, if breached or scored. And, unlike mats, there is no chance of snagging or pulling the material away from the sediment.
Applications include:
- Low permeability, thin capping material for contaminated sediments
- Seed delivery for wetlands
- Annular sealant for wells
- Anti-seep collar for underground pipes
- Dam or levee remediation
- Delivery of active capping materials (e.g., organoclay, activated carbon, aluminum sulfate, etc.) for the in-situ treatment of contaminated sediments