Case Studies: No. 3

Rochester RiversideGroundwater Remediation

The Site  

·       First Thames Gateway project, a flagship brownfield regeneration project.

 

·       Investigations indicated elevated concentrations of petroleum hydrocarbons originating from the former gas works.

 

·       The site is highly permeable with groundwater contamination (DNAPL and dissolved phase hydrocarbons) within the river terrace gravel and within the made ground at shallow depths.

 

·       Dissolved phase contamination of chalk aquifer.

 

·       The site is being redeveloped for residential and commercial end use.

 

The Solution  

·       Involves the application of several remediation technologies to address contamination:

 

o        Pulsed DNAPL recovery from deep boreholes;

o        Flow path management in parallel shallow trenches;

o        Chemical oxidation to remove dissolved phase contamination

 

·       Licensed by the Environment Agency under MPL, abstraction licence and discharge consent.  Asymptotic targets agreed with regulators.

 

 

The Results 

·       Regulatory closure for the flow path management and several boreholes.

 

·       Over 18,000 l of DNAPL tar recovered and approximately 2,200 kg of dissolved phase contamination. 

 

·       Significant reduction in risks posed to groundwater and human health.

 

·       Site works undertaken in conjunction with earthworks and other remediation contractors on a very busy site.

 

·       High profile project within the remediation industry, the Environment Agency and other regulators.

 

·       Recipient of the Brownfield Briefing Remediation Industry Awards Best Use of Combined Systems 2007.

 

·       On program to achieve closeout by end of 2008.