2.3.4 Remediation technologies 2.3.4.1 Introduction The current discussion and concern about groundwater contamination in the USA and Europe is due to recently detected evidence of fuel spills and leaks that have actually been happening for several decades. Some have taken place at storage sites and terminals but the majority have occurred at retail fuel stations, which is why this guide is focusing on retail sites. Generally, the situation is getting better due to improvements in technical installations and operating practices at retail stations. In the meantime, there is a lot of risk assessment and remediation work to do at past release sites, to understand and eliminate the contamination. MTBE has attracted attention to groundwater contamination because with its introduction in 1973. It brought several specific properties that distinguish it from other components: it has a very low taste and odour threshold, which means it is noticeable at low concentrations; it is more soluble in water, so in certain conditions it tends to spread faster and further through the soil, creating a "halo" effect around the spill; it biodegrades more slowly and therefore may persist in the environment for longer periods. A different issue in the USA concerns MTBE found in water in small concentrations, especially in certain recreational lakes, some of which also serve as water reservoirs. In those cases, the problem is not caused by leaking storage tanks, but by recreational boats' 2-stroke gasoline-driven outboard motors, which blow exhaust gases directly into the water. Combustion in such motors is less than complete, therefore a relatively large proportion of unburned fuel - including MTBE - ends up in the water. Splashing gasoline while filling up from containers, e,g, jerrycans, may also contribute to the problem, although probably on a minor scale. This picture may have been repeated to some degree in Europe. Early intervention The problem of MTBE in groundwater is not inherent to the product itself, but has mainly arisen from careless handling. It is an avoidable issue, which can be successfully resolved through co-operation between the oil industry, oxygenate producers, water companies and regulators. Early, preferably immediate, intervention following an accidental release of gasoline and its components is the key to minimising the extent and cost of remedial action and is essential to protect public health and the environment. Although the sense of urgency may seem less, dealing with past releases is equally important. In the case of a major past incident, the contamination plume continues moving along its natural path and given time, may develop into a serious problem. The common misconception, that remediating MTBE contamination is extremely expensive, is based on the experience of past releases in the United States, which were left for years to cover vast areas and go deep. Removal of traditional gasoline contamination of similar size would be just as costly. The reason for these long delays is unique to the USA, where the legal practice of punitive damages discouraged oil companies from taking action, since such an initiative could mean acceptance of liability. Remedial action There is a large array of well-proven remediation technologies for treating soil and groundwater contaminated by conventional gasoline. In general, these methods are applicable to gasoline containing MTBE. The most common methods are excavation of the contaminated soil (dig and dump), soil venting, air stripping, activated carbon or other adsorbent treatment and biological degradation. Traditional pump-and-treat technologies available for water treatment plants have been proven effective in remediation of gasoline-contaminated water, even if it contains MTBE. The hydrocarbons and oxygenates do degrade naturally in the subsurface soil and groundwater due to microbial activity. However, especially for ether oxygenates such as MTBE, the reaction rates are slow because electron acceptors, such as oxygen, are quickly depleted in contaminated soil and groundwater and are recharged only slowly. As a result, contaminated groundwater may have significant contaminant concentrations but depleted electron acceptors, whereas the overlying unsaturated zone may contain oxygen but low contaminant concentrations. Key principles The following information on remediation technologies is intended to provide a general understanding of the available options. When carrying out remediation work, a few key principles should not be forgotten: in acute gasoline spills/leaks, time is of the essence early contact with the appropriate authority is recommended importance of consultant/contractor selection an investigation very seldom reveals everything - there is always an element of uncertainty left a risk-based approach should be applied importance of contamination source (such as leaking equipment or contaminated soil) removal or control the effectiveness of a technology is largely dictated by the geological/hydrogeological conditions there are no two identical cases often various technologies are needed, in sequence or in combination contracting the remediation work to a consultant and/or specialist firm is best done on a written contract basis, clearly defining the respective liabilities due to uncertainties involved, cost estimates also tend to be uncertain. A lump-sum contract may or may not work especially when dealing with contaminated groundwater, the problem owner should not always expect quick and inexpensive remediation. An abundance of information on soil and groundwater remediation is available from bookstores, libraries, conference proceedings, international publications and of course, the Internet. This guide includes a Website Directory, which lists several useful Internet sites. The total volume of information available via those sites and their reference links is enormous. Most of the websites contain both soil and groundwater remediation technologies. Note: The websites are large, comprehensive and mostly well organised. However, it is advisable to take plenty of time, have a notepad and pen handy and systematically browse through the material. Keeping notes of the search path facilitates further visits to useful websites. Printing the websites' and subsites' front pages helps navigation later on. 2.3.4.2 Soil remediation This section outlines the major clean-up technologies that have become well established in commercial soil remediation. Generally, the technologies available today are:     - effective     - safe     - not prohibitively costly, provided that prompt action is taken There are many companies offering clean-up services with these methods and a reasonable case history has been built up. There are numerous remediation research topics and innovative techniques which are being investigated, for instance phytoremediation and electricity-enhanced techniques such as electro-osmosis, electrical heating and microwave heating, which are all emerging technologies holding substantial promise and which have been applied successfully on a small scale. Under natural conditions, biodegradation of MTBE in soil and groundwater may be slow. The main reasons are lack of oxygen and lack or too small population of specific micro-organisms. This can be enhanced in two ways: adding oxygen and selecting and adding appropriate micro-organisms and in some cases nutrients. The first can be done by a technique commonly known as air sparging. Addition of oxygen can further enhance the process. In general, remediation technologies can be grouped into categories using physical, chemical or biological methods. The various techniques usually work well when applied to a specific type of contamination, however, a universal technique solving all contamination problems does not exist. Due to the potentially complex geological and contaminant nature of many contaminated soils, it is frequently necessary to apply several techniques, often in sequence, to reduce the concentrations of contaminants to acceptable levels. Remediation techniques can also be categorised by the means with which they effect remediation. Some methods will eliminate wastes through reactions which produce benign (or at least less harmful) products. Thermal and biological methods (employing bacteria) are typical examples. Other methods, e.g. soil washing, incineration and vapour extraction, will concentrate wastes, resulting in a mass that may be easier - i.e less costly - to manage. Another approach is to fix the contaminants in place, (a method called soil stabilizing), thus eliminating or greatly reducing the risk of exposure to the public. Traditionally, the simplest way to remediate contaminated soil has been just to excavate the contaminated soil mass and locate it somewhere else, a method called "Dig and Dump". In such cases, oil and gasoline components typically decompose by microbial action, which can be considerably speeded up with proper stack composting arrangements. Today this is not always possible, or acceptable. Ever-tightening requirements and regulations for establishing and operating a dumpsite have resulted in fewer dumpsites being available, as well as greatly increased waste disposal costs. The transportation of contaminated soil has also become strictly regulated. For instance, in some areas, transporting and also dumping heavily gasoline-contaminated soil is totally forbidden. However, in minor incidents, excavation is still the most effective way to solve the problem. The websites listed below are all very large and comprehensive with various subsites and Internet links. As everybody knows how to use an excavator, these websites typically present more advanced technologies. Some of them also contain technologies that apply to groundwater remediation. Special note Non-Aqueous Phase Liquid (NAPL), i.e Free Phase Hydrocarbon Liquids Recovery Removing the contamination source from the soil, (in this case, a free phase of gasoline from the soil pores or from the top of the soil or groundwater) is of paramount importance to a successful remediation effort. If source removal is not properly performed, the remaining contamination is capable of feeding unacceptably high concentrations of gasoline components into the groundwater, or seeping through basement walls to contaminate the air in the basement, or maybe in the whole house, for a long time. Also, gasoline is capable of seeping through some polymer pipe materials to the extent that it may create problems with household water supplies. Gasoline smell and taste in tap water is not uncommon at sites where the soil is severely contaminated with gasoline or diesel, and the water supply pipes are made from polymer materials. Free-product removal can be a tricky and costly exercise, even when performed by experts. The following Internet link gives access to a presentation page of API publication No: 4729, August 2003, http://groundwater.api.org/lnapl/ appendix no. 16.pdf describes the design of free product removal installations and procedures. The reader should note that the document is very technical. It is included mainly for use by scientists and consultants. Information on free product removal methods can also be found at several websites included in this Guide. Hazardous Waste Clean-Up Information Website is an American (EPA) website that provides information about innovative treatment technologies to the hazardous waste remediation community. It describes programmes, organisations, publications and other tools for federal and state personnel, consulting engineers, technology developers and vendors, remediation contractors, researchers, community groups, and individual citizens. The site is managed by EPA's Technology Innovation Office and is intended as a forum for all waste remediation stakeholders. Note: The website below is very large and contains a number of sub-sites. It is advisable to take time and have a notepad and pen handy and systematically browse through the material. Keeping notes of the search path facilitates further visits to useful material. Printing the front pages of the various sites and subsites helps navigation later on. www.clu-in.org A short presentation of the contents and intent of this very useful and comprehensive EPA website covering the whole range of soil and ground water contamination related problems: EPA Remediation and Characterisation InnovativeTechnologies (EPA REACH IT) Do you need reliable information about remediation and characterization technologies? Would you like to know about sites at which those technologies are being implemented? EPA REACH IT* can help. EPA REACH IT, sponsored by EPA's Technology Innovation Office, is a new system that lets environmental professionals use the power of the Internet to search, view, download and print information about innovative remediation and characterisation technologies. EPA REACH IT will give you information about more than 750 service providers that offer almost 1,300 remediation technologies and more than 150 characterisation technologies. EPA REACH IT combines information from three established EPA databases, the Vendor Information System for Innovative Treatment Technologies (VISITT), the Vendor Field Analytical and Characterisation Technologies System (Vendor FACTS), and the Innovative Treatment Technologies (ITT), to give users access to comprehensive information about treatment and characterization technologies and their applications. It combines information submitted by technology service providers about remediation and characterization technologies with information from EPA, the U.S. Department of Defense (DOD), the U.S. Department of Energy (DOE), and state project managers about sites at which innovative technologies are being deployed. Those sources together provide you with up-to-date information, not only about technologies you can use to characterize or remediate a site, but also about sites at which those technologies are being used and the service providers that offer them. * EPA REACH IT is best viewed using Netscape Navigator or Microsoft Internet Explorer, version 4.0 or higher. A very useful sub-site of the above is http://clu-in.org/products/citguide which opens a website with descriptions of various technologies, especially written for non-experts. The Technology Innovation Office produced this series of Citizen's Guides to Understanding Innovative Treatment Technologies, which are four-page fact sheets that explain, in basic terms, the operation and application of innovative treatment technologies for remediating sites. 2.3.4.3 Groundwater remediation Groundwater contamination, with the consequent potential to contaminate drinking water, is the key concern of the general public and the authorities. The remediation of MTBE-contaminated groundwater was initially considered to be impossible, or at least extremely difficult. This belief had its origins in the low biodegradability, low affinity for organic carbon and relatively high water solubility of MTBE, as well as the fact that it does not evaporate from water as easily as other gasoline components (lower Henry's Law Constant). However, now that more thorough research has been carried out, various effective remediation techniques have been found. There are in fact several existing and commercially available methods, such as air stripping, steam stripping, diffused aeration, and adsorption, which are able to remove MTBE from groundwater, especially so when the ground water is pumped and treated in on-the-ground facilities, i.e. pump - and - treat. However, if the source of the contamination, (i.e. contaminated soil or even free phase product) is not removed swiftly, the remediation can take a long time and thus be very costly. In cases where a private well, serving one or two houses, has been contaminated, the immediate implementation of remediation methods such as Granulated Activated Carbon Adsorption (GAC) in the form of an in-line filter before the well water is used as drinking water, has proven to be adequate and quite cost effective. Early studies on MTBE contamination of groundwater stated that the compound was either non-biodegradable or very resistant to biodegradation. However, recent research has shown that MTBE can be degraded both aerobically and anaerobically, although the anaerobic intrinsic degradation is slow. The research has found that there are naturally occurring microbes capable of using MTBE as a sole carbon and energy source. Such micro-organisms seem to be widespread, but initially in low numbers that take time to reach a sufficiently dense population to sustain MTBE degradation. Laboratory experiments have clearly shown that biodegradation of MTBE is feasible. Recent field experience from various case studies confirmed this conclusion. Methods such as the trickling biofilter, membrane bioreactor, and in situ biological treatment, which specifically use the biodegradability of MTBE, are emerging and have demonstrated great potential. Selection of the remediation strategy and technique to be used in each situation should be done only after a careful evaluation of site-specific properties, since soil characteristics and hydrogeological conditions on site, as well as the possible presence of other contaminants, generally play an important role in selecting a strategy. When contaminated soil or groundwater is detected, the response should consist of a few key steps. This applies to all contaminants, including MTBE: Immediate control and cessation of the release, including repair or removal of the release source Removal of free product in both saturated and unsaturated (vadose) zone Removal of remaining product (this generally takes most time.) Efforts in the last steps of remediation are of little value if the preceding steps have not been taken. In fact, initiating remediation under such conditions can worsen the situation, as contaminants may be forced to migrate further. A rapid response to the detection of a contamination incident is essential to limit the spreading of the contamination. This holds true specifically for MTBE, as its properties enable quicker migration in both unsaturated and saturated soil than other gasoline components. Abundant and up-to-date information on various technologies is available via the Internet, for instance at: Ground Water Remediation Technologies Analysis Center's Website www.gwrtac.org - a large website on various innovative remediation technologies, vendor information, etc. This is one of several US EPA websites, most of which are interlinked. An excerpt from the front page and a sub page of GWRTAC's website is given below. Note: This website is very large and it contains a number of sub-sites. It is advisable to take time and have a notepad and pen handy and systematically browse through the material. Keeping notes of the search path facilitates further visits to useful material. Printing the front pages helps navigation later on. The Groundwater Remediation Technologies Analysis Center (GWRTAC) compiles, analyzes, and disseminates information on innovative groundwater remediation technologies. GWRTAC prepares reports by technical teams selectively chosen from: Concurrent Technologies Corporation (CTC), the University of Pittsburgh, and other supporting institutions. The GWRTAC documentation provides - among other material - 3 categories of reports and compilations on groundwater remediation technologies: Remediation Technologies Technical Documents - Technology Overview Reports Technical Documents - Technology Evaluation Reports Each category presents a slightly different view of the subject, describing different technologies and various levels of detail. A sample is given below. Remediation Technologies: GWRTAC focuses on innovative in situ groundwater and soil remediation technologies as compared to the standard "pump and treat" approach for groundwater, or soil excavation and treatment. Many of the remedial activities summarised within GWRTAC are in situ technologies requiring no groundwater extraction; however, means of enhancing pump and treat are also addressed. GWRTAC includes those remediation technologies which, through design and/or application, improve groundwater quality and are integral to groundwater clean up. The link below opens brief descriptions of technologies that are currently included in GWRTAC's list of Technical Documents on-line: http://www.gwrtac.org/html/techs.html Reference to GWRTAC's Glossary of Hydrogeology Terms may be useful during reading of the technology descriptions. www.ngwa.org is a useful source of additional information on soil and especially groundwater contamination, although it does not provide direct technology descriptions or evaluations. http://www.mst.dk/project/NyViden/1999/03070000.htm is a Danish study by the Institute of Microtechnology, Technical University of Denmark and the Institute for the Water Environment: "Remediation of MTBE-contaminated groundwater" (Prof. Erik Arvin, 1999). It summarizes the principles of various remediation techniques and assesses the usefulness of the techniques, providing a useful overview. http://www.enzymetech.com/applications/mtbe/mtbe_degrades.htm gives access to a company that uses biological systems and dissolved oxygen in in situ treatment http://www.estcp.org/projects/cleanup/CU-0015.cfm refers to information from Environmental Security Technology Certification Program (ESTCP) called "In Situ Remediation of MTBE-Contaminated Aquifers Using Propane Biosparging". http://www.aptwater.com/assets/tech_papers/Paper-TBAMTBE.pdf is a paper by Applied Process Technology, Inc (2004), presenting results from several pilot studies and fullscale remediation sites in which an Advanced Oxidation Process (ozone / hydrogen peroxide) was used to remove TBA and MTBE from contaminated groundwater. http://www.shellglobalsolutions.com/bioremedy/documentation/index.htm leads to the site of consultant Shell Global Solutions, summing up a dozen of projects and papers on (bio)remediation of MTBE contaminated sites.  It also contains information on Biobarriers and BioGAC (microbes seeded on granular activated carbon). 2.3.4.4 Drinking water remediation Remediation of large supply wells The California MTBE Research Partnership has conducted comprehensive research on drinking water remediation technologies. The Introduction from the Executive Summary of the research report is presented below, with a link to the actual Executive Summary (MS Word format - total of 20 pages, at the end of this chapter, ie. appendix no. 17.pdf) The results of the research indicate that, should MTBE removal from drinking water become necessary due to exceedance of the organoleptic or other limits, the cost of such service is not intolerably high. The table on page 12 of the Executive Summary gives information on the clean up costs in different cases. Treatment Technologies for Removal of MTBE from Drinking Water Air Stripping Advanced Oxidation Processes Granular Activated Carbon Synthetic Resin Sorbents Second edition - Executive Summary Introduction This Executive Summary is being published as a stand-alone summary of the key findings from the report, "Treatment Technologies for Removal of Methyl Tertiary Butyl Ether (MTBE) from Drinking Water: Air Stripping, Advanced Oxidation Processes, Granular Activated Carbon, and Synthetic Resin Sorbents, Second Edition (MTBE Treatability, 2000)". The complete report is available from the National Water Research Institute (NWRI) in hardcopy or as a CD-ROM. The report presents the results of an extensive feasibility study of methyl tertiary butyl ether (MTBE) removal from drinking water. The study was conducted to evaluate the most promising and/or widely accepted technologies used to remove volatile organic compounds from drinking water: namely, air stripping, advanced oxidation processes (AOPs), granular activated carbon (GAC), and synthetic resin sorbents. These technologies were evaluated as they apply specifically for removal of MTBE. The first edition of this document was published in December 1998. The second edition (MTBE Treatability, 2000) is a significant improvement on the first edition. The most notable changes are the addition of a new chapter on synthetic resin sorbents, refinement and update of costs for all technologies, significant revisions to the AOP section, a new introductory chapter, and a new chapter with overall conclusions and recommendations (appendix no. 17.pdf) Treatment of water supply from private water wells Soil, Sediment & Ground Water, MTBE Special Issue 2000. The article, Impact of Small Engine Spills and Treatment of Private Drinking Wells, in the above issue gives a good view on the topic. (appendix no. 18.pdf) Soil, Sediment & Ground Water, MTBE Special Issues 2001. The Spring 2001 issue also contains other very easy-to-read and informative articles on various topics around soil and groundwater contamination. . The complete issue is available at : www.aehsmag.com/issues/2001/spring/index.htm The March/April 2003 issue of the Soil, Sediment & Water magazine contained an article "Bioremediation in Bedrock: Using Bioremediation to Treat Dissolved BTEX and MTBE in Fractured Bedrock". It is available at http://www.aehsmag.com   Disclaimer