An in situ remediation technique applicable to saturated soil and the capillary fringe that consists of blowing pressurized air into saturated soil to cause the volatilization and desorption (stripping) of volatile and semi-volatile organic compounds. The process is often combined with the Soil Vapour Extraction (SVE) system for the recovery of contaminated vapours.
A simple and straightforward guide to explain the most common words, concepts and acronyms used on the website.
An in situ remediation technique applicable to the saturated zone and the capillary fringe that consists of injecting oxygen or air at a low pressure into the aquifer to stimulate the biodegradation of organic compounds adsorbed into the saturated soil, by the native microorganisms naturally present.
A biopile is an ex situ bioremediation technology in which excavated soils are mixed with soil amendments, formed into compost piles, and enclosed for treatment. Native microorganisms biodegrade hydrocarbon compounds under aerobic conditions, using them as a source of carbon and energy. The treatment involves piling layers of contaminated soil in which aerobic biological activity is stimulated through aeration and the addition of nutrients, minerals and water. Soil that has been treated can be reused for backfilling excavations.
BIOREMEDIATION (BIOLOGICAL CLEAN-UP)
A process that uses microorganisms or their enzymes, naturally occurring in environmental matrices (soil and water), to decontaminate sites and restore them to their original condition or to achieve concentrations below threshold values defined by an environmental/health risk assessment. It’s used as an alternative to traditional remediation processes to remove contaminants in situ, transforming them into non-toxic products or by-products. It is mainly applicable to the reclamation of organic compounds.
An in situ remediation technique applicable to unsaturated soil that stimulates the biodegradation by native microorganisms (naturally present in the soil) of organic compounds adsorbed into the unsaturated soil by blowing oxygen or air at a low pressure into the soil layers affected by the presence of organic contaminants. It can be applied in combination (alternating phases) with a Soil Vapour Extraction (SVE) process to ensure the removal of both volatile/semi-volatile and non-volatile hydrocarbon fractions.
The intermediate layer situated above the water table, between the “saturated” and “unsaturated” zone of an aquifer where ground water infiltration occurs by capillary action to fill pores in the soil. Pollutants that penetrate through the capillary fringe, due to this wetting-front movement or to groundwater table fluctuations, are subject to transport in the aquifer.
Final surface waterproofing cover of landfills or contaminated areas, the purpose of which is to isolate the waste from the external environment, minimise water infiltration and promote the environmental restoration of the site. It consists of a multilayer structure built with natural and geosynthetic materials. Typically, layers from top to bottom are topsoil, water drainage system, clay soil or a geocomposite of equivalent permeability, an HDPE waterproofing membrane and, finally, in some cases, a gas drainage system.
Studies, activities, site investigations and lab analyses designed to gather the data necessary to determine the type (nature) and extent (location) of contamination at a potentially contaminated site. This process is designed to establish criteria for cleaning up the site, identify and screen cleanup alternatives for remedial action, and analyze in detail the technology and costs of the alternatives. In Italy the site characterization refers to the items content in the Legislative Decree 152/06. After the characterization activities sanitary risk analysis will be performed for the identification of acceptable residual concentration levels.
CONCEPTUAL SITE MODEL (MCS)
The Conceptual Site Model (MCS) must be defined as part of the risk analysis required by Italian Legislative Decree 152/06 for potentially contaminated sites. This will be implemented following site investigations and lab analyses of the site and defined primarily based on a reconstruction of the characteristics of the three main components that make up the risk analysis (source, transport and target) for which the sources of pollution, the migration routes and the contamination targets must be defined.
CONTAMINATION THRESHOLD CONCENTRATION (CSCs)
Those limit values of contamination in groundwater and soils above which site characterization and risk assessment are required. In Italy, the CSC values are identified in Annex 5 of D. Lgs. 152/06 Part IV Title V.
E-HYREC® (Eni Hydrocarbons Recovery)
An Eni proprietary automated device for the selective recovery of light non-aqueous phase liquids (LNAPLs), generally hydrocarbons, floating on the top of the groundwater table as a separate phase. The device has a hydrophobic and oleophilic filter to recover only the LNAPL not the water. Due to the chemical and physical characteristics of the filter, once plunged at the interface between the LNAPL layer and the groundwater surface, the LNAPL phase permeates through the pores of the filter whereas the water is repelled. The filter is coupled with a booster pump to collect and send the LNAPL to a tank or stream.
A methodology developed by Eni consists of a combination of different monitoring methods applied to biological remediation thanks to a synergistic approach that includes microbiology (setting up microcosm cultures), molecular biology (quantification of key genes constituting specific and/or functional markers) and isotopic analysis (assessment of isotopic ratio using CSIA, Compound Specific Isotopic Analysis).
EMERGENCY SAFETY MEASURES (MISE)
As defined by the Italian Legislative Decree 152/06, any immediate, first response, short-term action to be taken 24 hours following the contamination event or detection. The actions are designed to contain or remove spreading of primary sources of contamination so as to avoid or limit the contact with soil and groundwater media, pending any further reclamation or operational or permanent safety measures. Once safety measures are in place a characterization plan is performed to define the extent of the contamination. Emergency Safety Measures must be communicated to the public administration that take note.
An in situ technique where nutrients, oxygen, or other amendments are used to help grow the population of indigenous or inoculated micro-organisms (e.g., fungi, bacteria, and other microbes) responsible for degrading (metabolizing) organic contaminants found in soil and/or ground water, and converting them to innocuous end products. Inorganic contaminants and metals, on the other hand, cannot be naturally biodegraded, however, the action of microorganisms can be used to change their valence state and cause them to be absorbed, immobilised or precipitated, resulting in lower concentrations in the environmental matrix affected.
ENVIRONMENTAL/HUMAN HEALTH RISK ASSESSMENT
Human health risk assessment quantifies the human or environmental toxicological effects deriving from the prolonged exposure to contaminated environmental matrices. It is used to define the need for remediation on potentially contaminated sites where the concentration in environmental matrices of one of the parameters listed by law and subsequent amendments and additions has exceeded the threshold concentration of contamination. According to Italian Legislative Decree 152/06), potentially polluted sites must be subjected to characterization and risk analysis to define the acceptable risk threshold concentrations. Only when these values are exceeded remediation or contaminants containment is required.
EX SITU/OFF-SITE TECHNOLOGY
A remediation method that involves moving the contaminated environmental matrix from its original location and subsequently treating it at off-site facilities such as authorised treatment plants or landfills.
EX SITU/ON-SITE TECHNOLOGY
A reclamation method that involves moving the contaminated environmental matrix from its original location and treating it at onsite facilities, usually with the aim of reusing the restored matrix.
GROUND WATER EXTRACTION
Suction and pumping of groundwater for subsequent transmission to a treatment plant for the abatement of contaminant concentrations
GROUNDWATER TREATMENT PLANT (GTP)
A set of specific processes used for removing contaminants from groundwater with the aim of making it compliant with its intended purpose — re-injection into an aquifer, discharge, internal reuse, or sale to a third party. The technologies used are chosen according to the contaminants present and the remediation objectives to be achieved. To this purpose, the system generally consists of chemical/physical sections (in case of SST, colloids, metals), acid and/or basic stripping (for VOCs), filtration through a granular medium (SST), filtration with activated carbons (to remove metals, VOCs, BTEXs), biological treatment (in the presence of organic compounds), membrane filtration (for SST, COD) and osmosis (for salinity).
A chemical and/or physical process for capturing and fixing pollutants in an inert matrix with the aim of reducing the pollutant potential and hazardousness of the waste and thus make it suitable for subsequent landfill disposal or recovery. Inertisation processes are divided into stabilization and solidification, vitrification and vitroceramisation.
IN SITU CHEMICAL OXIDATION (ISCO)
In situ chemical oxidation treatments involve injecting a mixture comprising a suitable oxidising agent into the contaminated matrix, which allows for the polluting organic substance to be completely transformed into carbon dioxide and water or partially transformed into substances with a simpler molecular structure that are more easily degradable.
IN SITU TECHNOLOGY
A remediation method for treating contaminated environmental matrices (soil and water) without removing them from their natural location (unsaturated soil, saturated soil, aquifer, etc.).
MONITORED NATURAL ATTENUATION (MNA)
A long-term passive contamination management/monitoring approach that exploits the self-purification capacity of the environment through a series of physical, chemical and biological phenomena that develop naturally in environmental matrices, such as biodegradation, dispersion, dilution, adsorption, volatilization, transformation and/or mineralization processes.
A technology that uses the effects of fungi to treat contaminated environmental matrices. Thanks to the acids and enzymes produced, the fungi are able to degrade and, to some extent, mineralize a wide range of organic pollutants and xenobiotics such as petroleum products, polycyclic aromatic hydrocarbons, chlorinated solvents, dioxins and furans, pesticides, herbicides, nitroaromatic explosives and drugs. Many fungi are also hyperaccumulators, meaning that they are able to tolerate and accumulate significant amounts of toxic substances such as heavy metals.
Simultaneous multi-phase extraction is an in situ treatment technique that uses vertical and horizontal wells to produce significant depression on the unsaturated area, in the capillary fringe and in the upper part of the saturated zone, with the aim of extracting gases from the soil, LNAPL and contaminated groundwater.
OPERATIONAL SAFETY MEASURES (MISO)
Actions carried out at an operating site to ensure an appropriate safety level for people and the environment, pending further permanent safety measures or remediation to be carried out once operations cease. These include contamination containment measures to be implemented on a transitional basis until reclamation is completed or permanent safety measures put in place in order to avoid the spread of contaminants within the same matrix or between different matrices.
PERMANENT SAFETY MEASURES (MISP)
Actions and measures to permanently isolate sources of contamination from the surrounding environmental matrices and to ensure a high and definitive level of safety for both people and the environment. In such cases, monitoring and control plans and limitations of use in relation to the provisions of urban planning instruments must be put in place
Application of phytoremediation to contaminated waters (groundwater, surface water, industrial wastewater, landfill leachate, etc.) through submerged flow or surface flow systems such as wetlands. Purification mechanisms take place by means of physical, chemical and biological processes (filtration, absorption, assimilation by plant organisms and bacterial degradation).
A technology that uses the effects of plants to treat contaminated environmental matrices. The purifying effects are concentrated in the rhizosphere (the part of the soil surrounding the plant roots) and exploit the synergies between plant roots, bacteria and fungi. The removal of contaminants is mediated by different processes and can therefore be classified as phytoextraction, phytodegradation, phytostimulation, phytostabilisation and phytovolatilisation. It is applicable to heavy metals, radionuclides, chlorinated solvents, BTEX, PCBs, IPA and pesticides.
PIEZOMETER (MONITORING WELL)
A tube that is placed in the soil for monitoring purposes, to depths below the water table and that extends to the soil surface. The monitoring well is perforated at the bottom to allow soil water to enter the tube and is equipped with durable casing and a screen section for taking water measurements and samples.
PUMP & STOCK
A combined system for extracting and subsequently storing groundwater before it is sent for disposal.
PUMP & TREAT
An aquifer remediation technique consisting of the extraction of contaminated groundwater through pumping wells and its subsequent treatment at a dedicated plant. The purified water can then be either fed into the sewerage system or into a surface water body, reused in industrial activities or reintroduced into the aquifer through re-injection wells.
PUMP & TREAT SYSTEMS
One of the most commonly used aquifer remediation strategies, although originally applied as a containment technique. It consists in completing a certain number of pumping wells in the contaminated aquifer (known as ‘barrier wells’) to collect and transfer contaminated groundwater to a dedicated plant for contaminant separation and treatment. Treated water is then discharged for disposal or further use. Pumping wells are mostly installed transversally to the groundwater flow (hydraulic barrier), creating a piezometric depression that capture the plume of contamination, preventing it from migrating downgradient.
A set of cleanup or corrective actions aimed at eliminating sources of contamination and contaminants or at reducing the concentrations of these substances in the soil, subsoil and groundwater to a level equal to or below the risk threshold values (CSR).
A document identifying measures, applicable technologies, costs and expected timeframe to achieve remediation. According to the provisions of Italian Legislative Decree 152/06, it must contain a comparative, site specific analysis of different applicable technologies, in terms of effectiveness in achieving the end goals, residual concentrations, execution times and impact on the environment. The analysis should outline the costs of different technologies and offer a comparison of the effectiveness of the proposed alternatives. The plan should also outline the necessary safety measures and the relevant controls and monitoring measures.
RISK THRESHOLD CONCENTRATION (CSRs)
Concentration thresholds of contaminants in environmental media above which certain remedial actions are recommended or enforced. The values are determined on the basis of site-specific risk analysis procedures, to be performed in accordance with the principles set out by Italian environmental law (Appendix 1 to Part IV of Legislative Decree 152/06), and represent the target values that must be reached through soil and groundwater remediation.
All of the inspection and restructuring operations to which industrial and/or treatment plants are subjected in order to adapt them to new operating conditions, ensure compliance with any new environmental regulations or enhance the performance of the entire production process.
A subsurface area in which all pores and cracks in rock and/or soil are filled with water. Groundwater movement is mostly horizontal and determined by the hydraulic gradient under the effects of gravity.
SITES OF NATIONAL PRIORITY
These represent very large contaminated areas, as recognised by the Italian State, that require soil, subsoil and/or surface and groundwater reclamation measures to be implemented. Sites of national interest are identified by decree of the Ministry of Ecological Transition, which oversees the reclamation procedure, and are comparable to Superfund sites.
An ex-situ (on-site and off-site) remediation technique that removes hazardous contaminants from soil by washing the soil with a liquid (often with a chemical additive), scrubbing the soil, and then separating the clean soils from contaminated soil and washwater. It is effective on petroleum hydrocarbons, VOCs, SVOCs and halogenates, as well as on recalcitrant compounds such as IPA, PCBs, dioxins and furans, pesticides and metals/metalloids.
SOIL VAPOUR EXTRACTION
An in-situ remediation technique that applies a vacuum to a series of wells (vapour extraction wells) and induces air flow through contaminated soil. As the air migrates through the soil, volatile organic compounds (VOCs) volatilize (evaporate) and move with the air to the extraction wells where they are removed from the subsurface. If the concentration of VOCs in the extracted air is high, the air maybe treated by a carbon adsorption system before being released to the atmosphere. In some cases, dual phase vacuum extraction is used to treat both groundwater and the overlying soil.
Upper soil layer, above groundwater level, where the interstitial spaces (i.e. the spaces, or pores, between the individual soil particles) may contain gas or water in varying proportions, but in a non-saturated condition. In this zone The movement of fluids is purely vertical and caused by the force of gravity. This natural phenomenon, known as “percolation”, allows rainwater, for example, to move through the pores in the soil.