Project description
On an active industrial site near the city of Dijon (Fr), a chlorinated solvents plume is migrating in the direction of a residential area. Recently, arrival of low concentrations of tetrachloroethylene (PCE) in the nearest groundwater well at the other side of the road has already been detected. As the geology in this region consists of low permeability marlstone – a mixture of clay and calcium carbonate – it is evident that the pollution is moving relatively fast in the secondary porosity of the aquifer. A previous attempt with the conventional direct-push technology on this site has shown that the marlstone is too hard to arrive at the desired depths. Therefore, the SPIN® injection technology has been chosen for this job.
Barrier application
Due to the inaccessibility of the source zone and the dimensions of the plume, it was decided to treat this groundwater pollution by one or more reactive bio-barriers. For a barrier application, a carbon source with relatively low mobility after injection has to be used. In this case, an emulsified vegetable oil (EVO) was selected in combination with a micro-nutrients mixture to stimulate the endogenous dechlorinating bacterial cultures.
Results
With the new Maxi-SPIN® injection rig in combination with the recently developed Gravel-SPIN® injection head, the hard and dense marlstone soil did not seem to pose any problems for qualitative injection. During the injection of the EVO-emulsion at 240 l/m between 1,5 and 10,0 m-bgl, arrival of the injection liquid was observed in the adjacent monitoring wells. Further monitoring of this 20-points pilot test will indicate the efficiency and longeivity of this bio-reactive barrier. These results, together with the SPIN® logging data, will be used to design the full-scale bio-reactive barrier(s).
Reaction: September 2020
Pollutant(s): CAHs (Tetrachloroethylene: PCE)
Pollutant(s): CAHs (Tetrachloroethylene: PCE)
Geology: Marlstone
Surface/length: 45 m
Number of points: 20
Depth interval: 1,5 – 10,0 m-bgl
Surface/length: 45 m
Number of points: 20
Depth interval: 1,5 – 10,0 m-bgl
Application type: Barrier application
Dosage: 240 L/m
Dosage: 240 L/m