Preliminary study for the environmental restoration of a contaminated lagoon in Arganda del Rey
In the municipality of Arganda del Rey and within the Southeast Regional Park of Madrid there is a lagoon locally known as the Contaminated Lagoon of Arganda. This lagoon is one of the most contaminated sites in the region of Madrid. The origin was from the illegal dumping of hazardous waste generated in the Piqsa-Ulbarri used oil regeneration plant until 1992 when the operation was closed down.
The environmental problem concerns the existence of 59,000 m3 of highly acidic hydrocarbon waste (acid tar), which were dumped into two artificial lagoons, one with a volume of 49,000 m3 and the other with 10,000 m3. These lagoons were generated by the removal of aggregates (gravel pits) that took place at many years beforehand. Additionally, it has been estimated that approximately 33,000 m3 of soil has been impacted by hydrocarbons and heavy metals. A further complication to the problem is the presence of the Alluvial Aquifer of the Jarama and its location within a natural regional park with special protection for the environment.
Preliminary work to design an environmental restoration project
After several characterization investigations, in the middle of 2013, the Community of Madrid commissioned Emgrisa to complete the preliminary work to design a project for the restoration of the contaminated lagoon with the principal aim to reduce the environmental risk and incorporating the site within the regional park.
The scope of the work included:
- The review and analyses of all of the information collected to date.
- An exhaustive Quantitative Risk Assessment for human health and ecosystems,
- Hydrogeological modelling,
- Pilot trials for waste extraction,
- Laboratory treatability tests on soil and waste,
- Evaluation of the best available remediation technologies to treat both the soil and waste,
- Health & safety requirements for working at this highly contaminated site,
- Development and justification of the conceptual basic engineering design for proposing the ideal solutions for the treatment of waste and soil.
Considering the remediation of this site will be a large scale operation, it has been proposed to split the work into three phases:
- Phase 1. Extraction of the waste and its use in facilities adapted to the in co-incineration of waste to generate energy.
- Phase 2. Soil and groundwater remediation.
- Phase 3. Ecological-landscape restoration for the integration of the site within the Southeast Regional Natural Park.
The methodologies and technologies to be used in each of the three phases are based upon the best optimal techniques applicable for use at this site, the regulations concerning hazardous waste and contaminated soils as well as the actual site conditions and limitations.
Phase 1: Environmental Restoration Project
In 2014, Emgrisa was tasked with the elaboration of the remediation project for Phase 1 of the environmental restoration. This consisted in the extraction, transport and adaptation of the waste to be used in a co-incineration furnace with an Integrated Environmental Authorization (IEA) which permits the use of fuel derived from waste as a fuel.
Based upon the method for extraction of sulphates from oil, this project has been divided into two phases:
- Phase 1: Extraction of about 85% of the waste volume using non-electrical hydraulic screw-thread pumps. The waste will be specially prepared on site prior to transportation to the final destination.
- Phase 2: Excavation of the remaining 15% of solid waste taking into care not to break the basal layer of the lagoon that provides a waterproof barrier against the influx of groundwater.
At present, the environmental restoration project contemplated in Phase 1, is being completed by the Community of Madrid.
