Industrial residuals can be complicated and expensive to clean up…especially when located in an environmentally sensitive area.
An implementation of a remedial action at a Superfund site involving potentially contaminated residuals within a wetland provided us an opportunity. We challenged ourselves to find a better, faster and more cost effective way to achieve an appropriate cleanup.
Ahead of us were clearly defined remedial action objectives:
Conventional remediation methods would have required excavation and relocation of the lower portions of the wetland and disposal of the contaminated sediment within the upper portion of the wetland. Then a multimedia cap would be installed over the contaminated sediments in the upper portion of the wetland and a surface water diversion channel would be constructed to divert surface water around the wetland. Finally, sheet piling was to be installed to divide the wetland into cells. This originally proposed remedial action would have cost approximately $40M.
Working within guidance we proposed an alternative cleanup method that would still meet all the defined remedial action objectives, but would save time, money and reduce the impact to those areas adjacent to the residual zone. This newly proposed remedy involved in-situ capping of the contaminated sediments within upstream portion of the wetland, and the development and implementation of a monitoring and assessment program for the evaluation of the rate of recovery of downstream wetland areas as a result of the implementation of this in-situ cap.
The engineered cap was created by using AquaBlok ® to minimize contact between the biota and the contaminated sediments. The AquaBlok® 3070FW was selected to create the cap itself. With a nominal pre-hydrated thickness of 6.5 inches and covered with a soil layer with a nominal thickness of 2 inches it created a sequestration cap that dramatically reduced the potential for long-term diffusion of contaminants into pore water and overlying surface waters.
This innovative remedial plan using the in-situ AquaBlok® cap cost approximately $8M. Not only did this solution save over $30M; it eliminated the destruction of over 30 acres of wetland and the removal of dense hardwood tress adjacent to the wetland stretching over a half mile in length.
You can read the full project description HERE.
On January 19, 2016 Ohio EPA closed the comment period for the proposed modification of the Section 401 Water Quality Certification of the Section 404 Nationwide Permits (NWPs) for Ohio, discussed in previous eblast. The proposed 401 modification has profound implications for any industry or regulated entity using NWPs for development in Ohio. Those activities particularly affected would be oil and gas exploration and production, road construction, natural gas pipeline and electrical line construction, other infrastructure and utility projects, and other regulated activities in streams that require any of thirty-one Nationwide Permits currently in effect.
Hull submitted detailed comments on the 401 modification reflecting our views of how the modified 401 certification could affect stream and wetland protection, current stream and wetland assessment practices, practical ramifications including timing and costs, and how the regulated community we serve could be affected.
The proposed 401 modification contains many important clarifications and eliminates certain arbitrary impact limits primarily affecting the shale gas pipeline industry, including the NWP-12 1,500-foot cumulative linear impact limit and the limit on construction of pipelines to a maximum of two HUC-8 watersheds. In addition, the current requirement for mitigation of temporary impacts to PEM wetlands is eliminated. On balance, however, the proposed 401 modification contains new regulatory review requirements and ambiguities concerning coverage that could render the Nationwide Permit process less effective at fulfilling its goal of expedited permitting for small surface water impacts with low potential for adverse effects.