Artigo publicado e apresentado no Congresso ABES \u2013 1992 \u2013 Este artigo faz uma revis\u00e3o da investiga\u00e7\u00e3o e remedia\u00e7\u00e3o dos regulamentos e processos em casos de contamina\u00e7\u00e3o do solo por derramamento de Petr\u00f3leo.<\/p>\n
A REVIEW OF INVESTIGATION AND REMEDIATION REGULATIONS AND PROCESSES<\/p>\n
This report covers an investigation and remediation review of contaminated sites. Mainly speaking, petroleum hydrocarbon contaminated\u00a0sites. First, it makes a gathering of international legislative framework and structure of contaminated soil control, using the Netherlands,\u00a0Germany, the USA and Brazil as references. It discusses some topics on investigation methodologies: (i) geological and hydrogeological\u00a0assessment; (ii) pollutant and source information review; (iii) definition and implementation of an “in situ” investigation\u00b7 plan; (iv) selection of\u00a0health and environmental criteria and comparison with measured concentrations; (v) corrective action plan. The article discusses\u00a0alternatives of site remediation, which include groundwater remediation techniques (“in situ” treatment, isolation, extraction and surface\u00a0treatment) and soil remediation techniques (\u201cin situ” treatment, excavation and surface treatment). Finally, it points out some trends of sites\u00a0remediation in Brazil and abroad.<\/p>\n
Groundwater contamination assessment; groundwater remediation techniques; petroleum hydrocarbon contamination; soil contamination\u00a0assessment; soil contamination legislation; soil remediation techniques.<\/p>\n
After the accident that happened in Guadalajara, Mexico, when fuel leaked into the sewerage system and caused a great explosion, the\u00a0concern about leakage and soil contamination with petroleum hydrocarbons remarkably increased. Considered a recent subject in\u00a0environmental control, the investigation and remediation of petroleum hydrocarbon contaminated soils in gasoline stations has had great\u00a0advancement in Brazil, concerning both the development of control methodologies by environmental agencies and studies carried out by\u00a0private organizations. An evidence to this fact is that S\u00e3o Paulo has housed two technical meetings on safety in gasoline stations. In practice,\u00a0however, soil investigation and remediation techniques and methodologies are not yet widely spread.
\nConsidering the subject of extreme importance, this paper will present a review on the regulations and criteria adopted in the Netherlands, Germany, the\u00a0USA and Brazil. Also discussed is a methodology to address the problem.<\/p>\n
The Netherlands<\/p>\n
The special characteristics of soil use in the Netherlands allowed soil clean-up techniques there to achieve the best standards in the world. Over 7,500\u00a0contaminated areas were identified, covering some 20% of the country’s area (De Bruijn, 1988). This fact justifies the concern to identify, characterize\u00a0and remediate such areas by setting up legal and financial mechanisms to clean and protect the country’s soil.
\nTwo principles govern soil protection:<\/p>\n
Multifunctional: the present use of the soil must not affect any possibility of potential uses in the future;<\/p>\n
Polluter-payer: the organization or individual that generated the pollution is liable to pay for thecosts of removing such pollution, unless\u00a0financially unable to do so.<\/p>\n
Among the legal mechanisms to meet soil protection policies, interim quality standards have been established. Such standards do not derive from\u00a0ecotoxicological methods but from other quality requirements, such as drinking water, food standards and others.<\/p>\n
They are interim because they, have\u00a0been setup as a first step of an interactive approach to establish standards fully based on cause-effect relations (Vegter, 1988).<\/p>\n
Quality standards include three concentration levels for each element\/substance:
\n<\/i><\/p>\n
A <\/i>– values below which the soil is considered not contaminated and above which a preliminary investigation is required in view of the uncertain pollution\u00a0and potential risk;<\/p>\n
B – values above which a more detailed investigation is required, regarding the contamination extension and the risks involved;<\/p>\n
C – values above which removal or clean-up is usually required to bring such values back to A levels. (Vegter, 1988)
\nThe values related to hydrocarbon soil contamination are mentioned in Table 1.<\/p>\n
Germany<\/p>\n
Contaminated soil investigation and remediation in Germany is also very advanced. In addition to high industrialization levels in this century, that country\u00a0also suffered much bombing during the two World Wars, on which occasions the soil was certainly polluted in several ways. As an aggravating factor, we\u00a0must remember that most of the country’s water supply comes from underground sources.<\/p>\n
This situation justifies the German behavior in relation to soil contamination as one of the strictest countries in this matter.<\/p>\n
The soil protection policy in Germany is ruled by the principle of preventing environment and human health risk caused by soil and groundwater contamination.
\nTherefore, a soil investigation and remediation schedule is established in soil contamination episodes, where decisions are based on the contamination risk assessments. In addition, clean-up costs are always taken into consideration so that they are acceptable in relation to the benefits obtained.
\nSo as to evaluate the need for soil and groundwater sanitation measures, German officials adopt the “Dutch List” as a reference, Tables 1A and 1B, associated to the investigation guidelines for classes 1 and 3 landfills, adopted by the German state of North Rhin Westphalia (IWL,1990).
\nThe German standards’ used in hydrocarbon soil assessments contamination are mentioned in Table 2.
\nThese values are used to evaluate soil and groundwater contamination status. They allow to decide on the need for further investigations or corrective measures.<\/p>\n
The USA
\nAs the most industrialized country in this century, the USA felt environmental pollution effects earlier. The USA public structure thus
\nanticipated itself for pollution control. As regards soil pollution, the concern with the investigation of contaminated soils, of which the
\nResource Conservation and Recovery Act (RCRA) is only an example, can be observed already in the Seventies. The polluter-payer
\nprinciple is noticeable and federal and state agencies have full authority to enforce soil remediation measures, to be taken by the owner,
\noperator or individual or organization liable for the problem.
\nSo as to finance such decontamination efforts, a US$1.6 Billion superfund was raised from taxes on crude oil and certain chemicals. The
\nfund covered costs of recovery activities and paid for the necessary measures to identify, enforce the remediation and obtain refunds from
\nthe liable parties.
\nThe criteria officially adopted to identify the need for corrective measures are based on the effects the contamination causes or may cause
\non human health and the environment. Safe concentrations in water (on the surface and in depth), soil (surface and underground),
\nsubsuperficial gas and air are calculated according to concepts of exposure ways and doses, so as not to affect men or the environment
\n(EPA, 1989).
\nTherefore, the federal EPA has been studying elements\/substances on health. Related to petroleum hydrocarbon contamination, we could
\nmention studies on benzene, ethylbenzene, toluene and xylene.
\nOn Table 3, you can see the concentrations, according to different criteria, for the parameters related to petroleum hydrocarbon soil
\ncontamination.
\nThe California EPA also uses other parameters as references for the investigation of petroleum hydrocarbon contaminated soils: TPH – Total
\nPetroleum Hydrocarbon and voe – Volatile Organic Compounds in the subsuperficial air.
\nBrazil
\nA country with a continental area and more recent industrialization, Brazil’s pollution problems became more clearly perceptible only in the last few years\u00a0and in a localized manner, mainly in large cities, industrial poles and sugarcane monoculture areas.
\nDespite having an environmental law which is considered advanced, Brazilian regulations on soil protection are still rather incipient. At the federal leveI,\u00a0there is no legal documentation on the subject, except for that referring to waste that can potentially pollute the soil.
\nIn S\u00e3o Paulo state, Decree # 8468 (08\/09\/76) deals with aspects of control over waste disposal on the soil, but there is no mention of contaminated soils\u00a0investigation or remediation. Decree # 32.955 (<\/i>07\/02\/91) deals with the conservation of natural groundwater sources in the state. The main elements\u00a0that relate to this subject are the following:
\n– requirement of detailed hydrogeological and groundwater vulnerability studies before implementing sources of great environmental impact\u00a0or danger, as well as protection measures;
\n– requirement of a detailed hydrogeological characterization for projects of waste disposal on the soil:
\n– requirement of monitoring and annual submission of reports on areas where there is waste disposal on the soil:
\n– in case of statistically proven changes in the water quality, the incorporator will be responsible to carry out the necessary work to recover\u00a0the groundwater.
\nSince Brazil has not yet adopted soil and groundwater quality standards, drinking water standards (groundwater) and international\u00a0references are used on taking decisions about remediation. But even in drinking water standards, concentration limits are mentioned only for\u00a0benzene. Without contaminated soils identification programs, such identification occurs only when the effects are actually perceived by the\u00a0neighboring population, thus limiting officially controlled sites to a small number. On the other hand, there are private investigation and\u00a0remediation initiatives by those responsible for the soil contamination, either for pressure from the international headcoropanies or because\u00a0of international transactions or other reasons.
\nThe first government program for contaminated soil mapping has just started in S\u00e3o Paulo city metropolitan area, implemented by the S\u00e3o\u00a0Paulo environmental agency in cooperation with a German development agency.
\nDue to frequent problems of fuel leakage detected in gasoline stations and their consequences, the guidelines for investigation and recovery\u00a0of soils contaminated with such substances are more developed in S\u00e3o Paulo state.
\nThe parameters adopted for decision-making on recovery measures are the same used in the USA, namely Benzene, Toluene ,
\nEthylbenzene, Xylene (BTE&X), TPH (Total Petroleum Hydrocarbon) and VOC (Volatile organic compounds).
\nADDRESSING THE PROBLEM
\nMore than other activities related to pollution control, soil contamination investigation requires great care in the planning and field stages.
\nThis is due to the fact that it is necessary to study a material which is not directly accessible, which demands high costs of drilling, tests and\u00a0collection of samples.
\nA work chart to address the investigation and remediation of petroleum hydrocarbon contaminated soils is mentioned in Figure 1. The work\u00a0phases are detailed as follows:
\nPhase I – Data Survey<\/b>
\nIn this phase, alI information and data relating to the suspect site are collected, including the following:
\n– plans and information about the existing facilities and equipment;
\n– data and information about soil pollution potential sources;
\n– history of soil contamination and spills;
\n– geological and hydrogeological information available.
\nPhase II – Preliminary Diagnosis<\/b>
\nBased on the initial data obtained, field work planning is carried out considering:
\n– specifications of field tests, assessments and studies:
\n– detailed schedule:
\n– material and human resources;
\n– logistics:
\n– service contracting.
\nThe plan is executed through the development of the following activities:<\/p>\n
Identification of contamination sources – <\/i>through examining the facilities and processes on the site, the history of leakage\/spillis and the results off field tests\u00a0and assessments (waterproof tests in storage tanks, products\/waste analysis, etc.)
\nField environmental diagnosis <\/i>– preliminary contamination evaluation through soil, groundwater and subsoil gas testing on the site. Such tests may be\u00a0carried out using portable testing equipment, test kits or field <\/i>gas chromatographers.
\nWith the information obtained, a first diagnosis is obtained of contamination signs. In case the tests produce a negative result, a continuing\u00a0environmental monitoring is suggested. If the results are positive, the area’s hydrogeological and environmental characterization is carried out.
\nThe preliminary diagnosis further allows to evaluate the need for short-term measures, which may include measures to control the soil contamination\u00a0sources and emergency actions to minimize possible risks to human health, the environment and existing facilities.
\nPhase III – contamination Characterization
\nFirst, the work necessary to characterize the contamination is planned. The planning stage includes the following:
\n– specifications for soundings, tests and geotechnical analysis;
\n– specifications for environmental assessments;
\n– specifications of procedures for drilling and sample collection;
\n– material and human resources;
\n– logistics;
\n– service contracting.
\nThe contamination characterization plan is executed through the development of two parallel activities:
\nHydrogeological characterization <\/i>– by using geological and hydrogeological data available, regional maps of soil use and the information obtained\u00a0from drilling on the site, the following data must be obtained:
\n– description of soil layers;
\n– data on the size of grains and hydraulic conductivity;
\n– direction of the freatic aquifer flow;
\n– use of the are a groundwater and soil.
\nEnvironmental characterization – <\/i>mapping and definition of the contamination plume, which are done through the following activities:
\n– implementation of a monitoring wells network in the freatic aquifer;
\n– evaluation of phases: (i) free, by means of collection and visual examination of groundwater samples; (ii) retained, by means of collection and chemical\u00a0analysis of subsoil gases, or collection and chemical analysis of the soil; (iii) dissolved, by means of collection and chemical analysis of groundwater;
\n– isoconcentration maps tracing;
\n– evaluation of the contamination plume direction.
\nPhase IV – Control Measures
\nThe decision on the need for soil or groundwater recovery measures is based on the international standards mentioned earlier and on assessments of\u00a0potential environmental risks of the contamination for human health or ecosystems.
\nTherefore, the pollutant’s concentration is calculated in the soil, water, air and plants. Models of massive means of transportation are used to sirou1ate\u00a0the contamination movement. The exposure evaluation must include the following:
\n– soil ingestion;
\n– ingestion of contaminated food;
\n– ingestion of the water supplied;
\n– inhalation of particulate vapor and materials;
\n– skin contact with contaminated materials.
\nThe standard values are defined based on hypothetical exposure ways of each receptor, for several soil use scenarios.
\nThe risks are evaluated through calculating the receptor’s exposure and comparing it to parameters such as the “systemic toxicants” or the “healthbased criteria for carcinogens” (Bulman, 1988).
\nIf there is need for control measures, a recovery plan is prepared for the area, considering the following:
\n– sanitation technology;
\n– sanitation limit-levels;
\n– implementation schedu1e;
\n– methods to dispose of contaminated materials that may be found in the area;
\n– sanitation monitoring plan;
\n– remediation alternatives to minimize the impact on receptors.
\nTECHNOLOGICAL ALTERNATIVES FOR REMEDIATION
\nIf there is need for adopting soil pollution control measures, the adequate technological alternative is defined, according to an evaluation of the\u00a0characteristics of contamination, the area and related costs. On Tables 4 and 5, some technological alternatives for the recovery of petroleum\u00a0hydrocarbon contaminated soils and freatic aquifers are listed and commented.<\/p>\n
These alternatives are described below.
\nFreatic Aquifer Clean-up
\nLocal Treatment<\/i>
\nThis alternative’s main characteristic is to treat the freatic aquifer’s contaminated areas with a minimal soil excavation or water extraction. The options\u00a0adopted include physio-chemical or biological treatment, according to the summary on Table 6.<\/p>\n
Plume Cutoff<\/i>
\nIt refers to isolating the contamination plume by means of barriers, thus minimizing related risks.
\nThe main methods known to cutoff contamination plumes in aquifers are listed below:
\n– use of cutoff barriers, such as mud wells, earth curtains and stake walls. These barriers must have extraction wells to reduce pressure at
\nthe barrier:
\n– use of a hydraulic barrier consisting of a system of extraction wells in the contaminated aquifer so as to cutoff the plume:
\n– cutoff trenches to stop the flow in less deep aquifers.
\nWe shall not forget that the selection of a plume cutoff method requires a detailed examination of the aquifer physical and geological
\nconditions.
\nExtraction <\/i>and surface treatment
\nThe most widely used corrective action is the extraction of the aquifer’s contaminated water (through gravity flows in trenches and drains, or
\nthrough pumping), followed by the surface treatment through traditional chemical engineering processes. This alternative of extraction and
\nsurface treatment is generally combined with the plume cutoff. The contaminated water extracted from the aquifer may be treated using
\nindividual or combined biological, chemical, physic or therma1 treatment processes.
\nSoil Clean-up
\nChemical Treatment<\/i>
\nThis alternative requires the use of chemicals to transform the contaminating agent into a non-toxic element. The treatment may be used
\nindividually or combined with a biological treatment to reduce or to eliminate the soil contamination. This alternative is usually adopted in
\ncases when the soil contamination is caused by watersoluble light compounds. The procedure adopted is to promote leaching of the
\ncontaminated soil 1ayers, with the use of detergents and a subsuperficial drainage network.
\nBiological Treatment<\/i>
\nThis alternative includes the local treatment of the soil contaminated parts by using microorganisms or enzymes that can degrade the
\ncontaminating agents. It is usually adopted in cases when the soil contamination is caused by heavy organic compounds. The procedures
\nadopted aim at the degradation of the contaminating agents, accelerated by airing the soil (through ploughing) and adding nutrients (an
\naqueous fertilizer solution).
\nThermal Treatment<\/i>
\nThis alternative requires removal of the soil contaminated parts and elimination of the contaminating agents through incineration. This
\nprocedure supposes high costs and is thus adopted only in very restricted contaminated areas with highly toxic contaminating agents.
\nFINAL DISCUSSION
\nDue to severe soil contamination cases in gasoline stations, oil companies and environmental agencies in Brazil begin to search for stricter
\nenvironmental standards. Waterproof tests and environmental assessments of soil contamination are usually required when gasoline
\nstations change their flags.
\nTherefore, the work methodology must be adjusted according to each specific case and there must be special care during the planning and field stages.
\nThe parameters adopted and assessment methodologies must be carefully calibrated to validate the proposed addressing model.
\nThe use of the soil along with potential contamination risks will increasingly dictate the need for remediation measures, as well as their limitations and the
\ntechniques adopted to accomplish the desired goals.
\nREFERENCES:
\nDe Bruijn, P. J., De Walle, F. B. (1988). Soil standards for soil protection and remedial action in the Netherlands. In: Contaminated Soil ’88, K. Wolf, W.
\nJ. Van Den Brink, F. J. Colon (Ed.), Vol. 1, ed. Kluwer Academic Publishers, Dordrecht, PP 339-349.
\nBulman, T. L., Hosler, K. R., Ibbotson, B., Hockley, D., Riddle, M. J. , (1988) , Development of a model to set clean-up criteria for contaminated soil at
\ndecommissioned industrial sites. In: Contaminated Soil ’88, K. Wolf, W.J. Van Den Brink, F. J. Colon (Ed.), Vol. 1, ed. Kluwer Academic Publishers,
\nDordrecht, pp 299-308.
\nInstitut F\u00fcr Gewerbliche Wasserwirtschaft und Luftreinhaltung e.V.-IWL (1990). Altlasten Info
\nKovalick Jr., W. W. (1988), Implementing the new superfund: an ambitious agenda for EPA, In contaminated Soil ’88, K. Wolf, W. J. Van Den Brink, F. J.
\nColon (Ed.), Vol. 2, ed. Kluwer Academic Publishers, Dordrecht, pp 1505-1514.
\nOffice of Solid Waste, united States Environmental Protection Agency (1989). Interim Final RCRA Faci1ity Investigation (RFI) Guidance, Vol. 1.
\nVegter, J. J., Roels, J. M., Bavinck, H. F. (1988) Soil quality standards: science or science-fiction. In: Contaminated Soil ’88, K. Wolf, W. J. Van Den
\nBrink, F. J. Colon (Ed.), Vol. 1, ed Kluwer Academic Publishers, Dordrecht, pp 309-316.<\/p>\n