The LIFE SURFING test tackles the dense residues which are the cause of the contamination

What is the test about?

At the old Bailin landfill, pumpeable dense residues are considered exhausted. What is now remaining is this dense residue stuck to the wall fractures, non-pumpeable or residual, and which causes the groundwater pollution once they enter into contact. In consequence, to destroy these dese residues stuck to the bottom of the rock fractures means to eliminate the contamination cause. This is the objective of LIFE SURFING project, that combines the use of remediation techniques on the site’s surface with techniques performed inside the rock fractures using chemical oxidation and the action of surfactants.

Currently, there is an estimate of 3 to 4 m3 of non-pumpeable dense residues in Bailin. They are located in fractures of up to 40m depth inside an only layer of sandstone that has from 4 to 6 m thick and is affected in around 500m length. This is the only layer that is connected with the Gallego river. And this technique will be applied at a large scale only in this layer, which occupies around a 2% of the area of the old landfill’s surface.

Chronology of the test

During the development of the test, the following is foreseen:

• In 2019, different reactive and surfactants will be tested at a laboratory scale, to complete the test design.
• In 2020, the field works will start, such as the accesses, new boreholes, the hydraulic assessment of the new fractures intercepted.
• In 2021, the field tests will be completed and the SURFING technique will be tested in a large scale laboratory test of several cubic metres, that will allow for its transferability to granular aquifers and other residues, such as creosotes and PCBs.
• In 2022, the results will be elaborated. If results are positive, the conditions for its application to the complete sandstone layer will be determined.

The test will be developed over 60 linear metres of a vertical sandstone layer. The total area to be remediated is around 600 linear metres of sandstone layer in the old Bailin landfill.

Test phases

In a first phase, the extraction of dense phase enhanced by the action of surfactants will be performed. After its decanting and the obtaining of dense phase, the contaminated water will be pre-treated with three parallel systems. The first one consists in the oxidation using persulphate, with alkaline activation. The second is the hydro-oxidation and subsequent retention of generated volatile compounds in activated carbon. And the third is the retention in activated carbon and subsequent partial recovery of this carbon with the oxidation using persulphate with thermal activation. The resulting water will be sent to storm water pools for its treatment.

These treatments will be done on the surface of the old Bailin landfill.

In a second phase a series of injections will be done inside the boreholes to generate an oxidation enhanced with surfactants. Depending on the rebound effect, several weeks may pass between injections.

In a third phase a series of injections will be done to oxidize dissolved contaminants. Depending on the rebound effect, several weeks may pass between injections.

The test consists in analysing the efficiency of each one of these methods.

Barrier zone

The use of surfactants (industrial soaps) consists in mobilizing contaminants to oxidize them. To avoid the leak of pollution out from the test area, an area for the injection of oxidants and aeration in boreholes has been created 300m downstream the test area. This way, the sealing of the vertical rock layer is ensured.

LIFE funds commit with the lindane challenge.

In conclusion, this EU contribution, via LIFE funds, will allow for the increase of the safety conditions of the old Bailin landfill and of the use of water of the Gallego river. LIFE funds come from the European Union and its objective is the development of pilot tests of new technologies not tested before on field, either tested under new conditions. It has a demonstrative character and it gives value to projects whose results are transferable to other locations with similar environmental challenges. The collaboration among partners of different countries is therefore a key aspect of the project. The LIFE SURFING proposal was one of the selected ones among 507 proposals submitted in the environmental area.

Removal of the contamination

The results obtained in the preparatory actions are currently being processed, in order to start with the public procurement of the construction of the field test infrastructures.