Limitations of slurry walls - Team Gamma, by George Schuler
The purpose of slurry walls is to reduce the movement of unconsolidated materials. Slurry walls are constructed by digging a trench with a backhoe; at the same time the trench is filled with a mixture of bentonite and soil or cement. This filling of the trench prevents the walls from collapsing. The walls then solidify and a barrier is created between contaminants and groundwater. Slurry walls are most effective when the wall contacts the bedrock beneath, so the possibility of contaminant migration is minimized. Slurry walls can be effective prevent the migration of LNAPL’s when bedrock is not near the ground surface. However if another contaminant is present it is possible for that contaminant the pass underneath the slurry wall. One disadvantage of slurry walls is that the composition of the contaminant or soil might not be compatible for this type of remediation technique. Slurry wall’s are very cost and labor intensive. If the bedrock is too far beneath the ground surface and the type of contaminant is resting on the bedrock, then a slurry wall would not be suitable choice. Slurry walls also require a large construction site in order to excavate soil and mix the slurry.
References
Opdyke, S. M., & Evans, J. C. (2005). Slag-cement-bentonite slurry walls. Journal of Geotechnical & Geoenvironmental Engineering, 131(6), 673-681.
Pichtel, John. (2007). Fundamentals of Site Remediation. Lanham, MD: The Scarecrow Press, Inc.
Bioreactors- Tracie Panzek
The most common bioreactors are used in the treatment of groundwater that has been pumped to the surface. Groundwater is transferred to a large vessel or basin where microorganisms breakdown organic matter into a sludge or slurry that can be disposed of or recycled.
Bioreactors are used mainly to treat VOC’s and fuel hydrocarbons in soil and groundwater. It is not very effective in treating pesticides. Not all of the contaminants in the groundwater are biodegradable and they will not completely degrade. Heavy metals are not treated by this method and they can be toxic to the microorganisms that are being used to treat the water. There are also concerns that some of the products may be more dangerous or toxic than the original contaminants.
Cost is another limitation due to the specific design and size of the system. The dilute nature of contaminated ground water often will not support an adequate microbial population density. Additional nutrients may need to be added. Low ambient temperatures significantly decrease biodegradation rates, resulting in longer cleanup times or increased costs for heating. Air pollution and other controls may need to be applied before the slurry or sludge is recycled due to some of the volatile compounds that are produced in the process.
References
Pichtel, John. (2007). Fundamentals of Site Remediation. Lanham, MD: The Scarecrow Press, Inc.
http://www.cpeo.org/techtree/ttdescript/biorec.htm
http://www.frtr.gov/matrix2/section4/4-42.html
Granular Activated Carbon Filtration Limitations – Team Gamma, by Robert Sandoval
Granular activated carbon filtration is used mainly as a tertiary treatment system, used behind the secondary wastewater treatment system. This method is used mainly for the removal of a wide range of organic compounds, inorganic compounds, and heavy metals by absorption (U.S. Environmental Protection Agency [EPA], 2000). Although it is an effective method to remove small quantities of these types of contaminates, the following disadvantages are inherent in utilizing GAC absorption (EPA, 2000):
1. Possibility of odor and corrosion issues as a result of hydrogen sulfide development due to bacteria activity.
2. Wet GAC can be abrasive and can also contribute to corrosion issues.
3. Non-regenerated GAC, containing absorbed contaminates, may contribute to disposal challenges.
4. Tertiary treatment of wastewater with GAC requires that the water: meet conditions of low suspended solids, fall within a designated pH range, fall within a certain temperature range, and have limits on flow rate.
In addition to the inherent disadvantages of using GAC absorption processes, several exist with regards to the regeneration process, removing the absorbed substances from the absorbent; these include (EPA, 2000):
1. Exhaust emissions contain the absorbed VOC’s, requiring secondary air cleaners
2. Excess noise originating from the regeneration furnace
3. The regeneration process usually requires 24-hour operation
4. The regeneration process is inclined to experience mechanical problems.
U.S. Environmental Protection Agency. Office of Water. Municipal Technology Branch. (, 0). Wastewater Technology Fact Sheet: Granular Activated Carbon Absorption and Regeneration (09/2000 ed.) (EPA 832-F-00-017). Washington, DC: U.S. Government Printing Office. Retrieved November 1, 2009 from the World Wide Web: http://www.epa.gov/owm/mtb/carbon_absorption.pdf.
Disadvantages of flushing metals from soils using chelating agents-Amanda Rasmussen
Soils contaminated with metals may be “treated” by flushing them with acids, chelating agents, or other solvents. This is one type of remediation technology among many. The efficiency of this type of treatment may be dependent on soil pH, particle size, and the presence of other compounds, for example. Some examples of chelating agents that may be used are ethylenedinitrilotetraacetic acid (EDTA) and diethylene triamine pentaacetic acid (DTPA).
While EDTA and DTPA may be good chemicals to flush contaminated soils of metals there are disadvantages to their use. These chemicals may leave trace amounts in the soils after flushing causing them to migrate into water sources. These two chemicals if released in natural waters can affect the natural aquatic environment, by being persistent compounds. Both EDTA and DTPA, are not suspected to toxic to aquatic organisms, though in combination with other compounds they may be acutely toxic. With this the release of EDTA and DTPA should be minimized when possible.
EDTA has become known as a persistent organic pollutant, meaning the chemical is resistant to environmental degradation. Traces of EDTA may be left in the soil after flushing and removal of the metals from the EDTA itself. These traces may be cause of widespread human exposure, depending on what the site will be used for after remediation. EDTA also has been shown to have a low acute toxicity to rats at an LD50 of 2-2.2 g/kg and also being cytotoxic and genotoxic. . Oral exposure has been shown to cause reproductive and developmental effects.
Fundamentals of Site Remediation, second edition, Pichtel, John
http://en.wikipedia.org/wiki/EDTA
http://www.ncbi.nlm.nih.gov/pubmed/9297986
Disadvantages of the Groundwater Pumping Method of Site Remediation-Steve Peckerman
Groundwater pumping has been used as a remediation technique with for many years. Despite the successes it had had there are still significant drawbacks to this method of site remediation.
One of the largest factors in this process is the cost. In addition to the cost of the well the removed water must be treated and either reinjected or discharged elsewhere. The cost of a pump and treat operation may run anywhere from $50,000 to $5 million (Moyers, 1997) A relatively new technique of directional drilling can be even more costly, as high as $850,000 per well. (Miller, 1996)
Another drawback to groundwater pumping is time. A pump and treat plan may last many years. This length of time serves to increase the cost due to upkeep of equipment, create a negative public sentiment and may result in a need to redesign the pump plan due to changes in geology and groundwater flow.
Results of the groundwater pumping plan are significantly affected by subsurface geology, more so than many other techniques. This can result in well designed plan not being as effective as hoped. A contamination plume that splits may not be a able to be contained with the original plan and may require a redesign. If the plume goes under property that is inaccessible there may be a need for directional drilling. As mentioned above this can be even more costly than conventional drilling and is subject to limitations on depth and vulnerability to fluctuations in the water table and subsurface geography.
The efficiency of pump and treat operations is fairly low typically removing only 1/3 of NAPLs. Using enhanced pumping systems this can be increased to the 50%-80%range. (Moyers, 1997)
Reducing contamination to levels where groundwater consumption is safe is often beyond the capabilities of pump and treat operations .
Contaminated Sites Management Working Group. (2003, September 7). Site Remediation Technologies: A Reference Manual. Retrieved November 1, 2009, from Contaminated Sites Management Working Group: https://www.ec.gc.ca/etad/csmwg/pub/site_mem/en/c5_e.htm#521
Miller, R. R. (1996). Horizontal Wells. Pittsburgh: Ground-Water Remediation Technologies Analysis Center.
Moyers, J. ,. (1997). Disadvantages of Pump and Treat Remediation.
SGC Industries. (2004). A review of Remediation Techniques. Retrieved November 1, 2009, from www.scgindustries.com: http://www.scgindustries.com/techniques.html
Soil vaporization-Michael Rice
Soil vapor extraction is an effective technique used to remove volatile organic compounds from soil. Although it is effective in most circumstances, there are some limitations that environmental managers must be aware of before selecting this technique for remediation. The type of chemical being remediated is one consideration of soil vaporization extraction’s effectiveness. Soil vaporization extraction is limited to volatile organic compounds. The removal of heavier VOCs is one limitation since soil vaporization is mostly effective on lighter VOCs. The effectiveness of soil vaporization depends upon the rate at which the contamints can volatilize. Volatilization allows contaminats to be removed through vapor diffusion to the surface. Therefore, limitation of this method is that more volatile compounds can be more effectively remediated than less volatile compounds. The site of where this technique is to be used is another consideration. The water content of soil is a site consideration needed to determine the effectiveness of soil vaporization extraction. Dry soil has a grater rate of volatilization than wet soil so wetter soil is a limitation of this technique. Soil vapor extraction is only effective in the vadose zone. It does not work on groundwater. It does not work or not as effective to surfaces near groundwater or in areas that have groundwater fluctuations. Soil content is another factor. Soil evaporation is successful in lighter and porous materials like sand and gravel rather than heavy and impermeable materials like clay. Other considerations for this technique are its impacts on air pollution due to the release of vapors. Air permits are required as well as additional air pollution treatments.
References:
1) Soil Vapor Extraction (SVE) General Principles and Site Applications Former Marine CorpsAir Station El Toro (May, 25, 2005). [Online]. Available: http://www.bracpmo.navy.mil/base_docs/eltoro/documents/enviro_docs/SVE_Presentation_052505.pdf [2009, Nov. 1]
2) Pichtel, John. (2007).Fundamentals of Site Remediation. Government Institutes, Lanham
Disadvantages of Construction Wetlands-Amanda Mann
One of the major disadvantages of construction wetlands is the large amount of land required for this system. In areas where land is expensive it would not be cost effective. Another issue is that additional technologies may be needed for the wetlands to function properly. Solid wastes may need to be filtered in order to avoid a buildup of sediment which can decrease the efficiency of the construction wetlands overtime. A variable water flow rate can be a problem and may require a flow equalization basin. With certain types and high concentrations of waste pretreatment may be necessary. Some pollutants are not capable of being broken down in a construction wetlands and would require other means of treatment. The time that is needed to start up the system is also an issue. Plants require time to grow and become established before the wetlands can work efficiently.
Brookhaven National Laboratory. Technology Fact Sheet Peconic River Remedial Alternatives Wetland Restoration/Construction. Retrieved October 30, 2009, from www.bnl.gov
Federal Ministry of Economical Cooperation and Development. Facts and Frequently Ask Constructed Wetlands: A Sustainable Option for Wastewater Treatment in the Philippines. Retrieved October 30, 2009, from www.watsansolid.org.ph
Wetlands Pacific. Questions and Answers about Construction Wetlands. Retrieved October 30, 2009, from www.wetlandspacific.com
Tuesday, November 3, 2009
Team Beta - Site Remediation
TEAM BETA – SITE REMEDIATION
Environmental Settings for use of Granular Activated Carbon
Cherie Jourdan
31Oct09
Granular Activated Carbon (GAC) is most effective at the removal of pesticides, volatile organic compounds (VOCs), chlorine, benzene, trihalomethanes, radon and multiple other man made chemicals typically found in our tap water. If properly developed, GAC can also remove some heavy metals, Giardia and Cryptosporidium.GAC filters are not successful at removing sediment and particulates therefore they are often in conjunction with sediment filters. GAC filters would not be found in a system that is primarily looking to remove such items as sediment and particulates.GAC Technologies are often found in contaminated river beds where other remediation technologies have been deemed too complicated or too expensive. In a river bed, the GAC will have the opportunity to absorb contaminants on a continuous basis.Even more common than a contaminated river bed, GAC is often found in a filter column treating unfavorable tap water. GAC is often found in systems that can treat tap water on a slow continuous basis rather than a fast acting, immediate one.
References:
Activated Carbon Water Filters and Purification (Granular/Granulated and Carbon Block). (n.d.). Retrieved October 31, 2009, from http://www.home-water-purifiers-and-filters.com/carbon-water-filter.php
Kvech, S., & Tull, E. (n.d.). Activated Carbon. Retrieved October 31, 2009, from http://www.cee.vt.edu/ewr/environmental/teach/wtprimer/carbon/sketcarb.html
Environmental Settings for use of Subsurface Barriers: Slurry Walls
Carin Kelley
2November 2009
Subsurface barriers like slurry walls can provide a barrier to contain hazardous chemical contaminants from migrating or prevent mixing of contaminant groundwater with uncontaminated groundwater and act as a filter to lower acidic pH levels in the groundwater, or be used to change the direction of groundwater flow.Slurry walls are made up of soil, bentonite clay, and water that provide low permeability at a low cost. They can be used in all types of soil including those below the groundwater table. However, the soil bentonite cannot withstand strong acids, bases, salts and/or organic contaminants. Under those chemical conditions, other bentonite mixtures are utilized, such as; cement bentonite, attapulgite, or slurry geomembrane composite which are generally used as barriers for landfill leachates and salt water.The construction of the slurry wall depends on the chemical properties. Near the groundwater table, the slurry wall will essentially be ‘hanging’ to capture the floating contaminants with low densities such as gases, oils, or fuels. For contaminants that are soluble, such as; metals, organics, or salts, a slurry wall that is connected to bedrock is more feasible to utilize. The physical properties of a common slurry wall can be placed as deep as 100 feet, a thickness of 2 to 4 feet, with a hydraulic conductivity of 1 x 10-6 centimeters per second. Most often, for effective pollution control, the slurry wall is connected to bedrock 2 to 3 feet.
References:
FRTR Remediation Technologies Screening Matrix and Reference Guide, Version 4.0 (n.d). GW Containment Remediation Technology 4.52 Physical Barriers. Retrieved 1 November 2009, from http://www.frtr.gov/matrix2/section4/4-53.html
U.S. EPA (17 July 2009). Engineering Technical Support Center (ETSC). Retrieved 30 October 2009, from http://www.epa.gov/nrmrl/lrpcd/rr/etsc/physchem.htm
Welcome to Slurry Wall.Com (2005). Detailed Specification for Slurry Walls Including Off-Site Disposal of Excess Slurry Off-Site Materials for Slurry Wall Backfill. Retrieved 30 October 2009, from http://www.slurrywall.com/slurry-wall-specifications/default.asp
Welcome to Slurry Wall.Com (2005). Slurry Wall, Cutoff Wall, Slurry Trench Technology Overview. Retrieved 1 November 2009, from http://www.slurrywall.com/slurry-walls-technology/default.asp#WHAT-ARE-SLURRY-WALLS
Capping Systems
Arell Gray
2 November 2009
One relatively inexpensive way to control the infiltration of surface water to a contamination plume is to build a capping system. The purpose of the cap is to block infiltrating surface water and to prevent the spread of the contamination to the groundwater or to stop the emission of subsurface gasses, it also provides a stable surface to cover the contamination and improves the general looks of the site. Though capping does not actually remove any contamination from the soil, it keeps the contamination local and prevents further spreading of the plume. In many instances, excavation of the contaminated soil takes place prior to the capping to even further insure the prevention of plume migration.A variety of capping materials can be used, from natural soils to synthetic liners, and they can be designed with varying complexity from single layer caps to multilayer capping systems. The different methods used when installing capping systems vary due to several site condition variables, such as the chemistry of the contaminate, climate, type of soil, financial constraints, or future plans for the site. When these conditions are all factored in, a decision can be made about the capping material and the complexity of the system.
Capping Materials
Natural- Natural barriers include fine grained soils like clays and clayey silts. When locally available natural capping materials can be very cheap in comparison with synthetic materials. Natural barriers also are very durable and can work effectively for many years. The process is fairly simple, just lay out the capping material and compact it using heavy machinery.Synthetic membranes- Many non-permeable synthetic materials exist and are very effective at keeping contamination from spreading. The wide variety of materials make it possible to contain a wide variety of contaminates. Once a surface is prepared over the contaminated soil, layers of synthetic membranes are placed down and sealed together. These synthetic membranes usually come in rolls of sheeting 20-140 mils, widths of 15-100 feet and lengths of 180-840 feet. The number of layers and what they are composed of is determined due to the site conditions. Extra care must be taken when installing the sheeting because any tear or puncture compromises the integrity of the cap. Another concern is the vegetation that grows on the cap, plants that have deep driving roots may also puncture the cap.
Synthetic Capping Materials include;
*HDPE (high density polyethylene)*VLDPE (very low density polyethylene)*PVC (Polyvinyl Chloride)*CSPE (chlorosulfonated polyethylene)*EIA (ethylene interpolymer alloy)*urethane*polypropylene*proprietary formulationsPavement- Asphalt or concrete, though unsightly, make an effective and easy cap for temporary capping of large areas.Multilayer systemsMany caps are composed of multiple layers. The base of which is a non-permeable or low-permeability layer either natural or synthetic. The middle layer is a permeable layer like sand or gravel and the top layer is made of vegetated native uncontaminated topsoil. The vegetation keeps the cap from eroding and provides aesthetic value, however vegetation with shallow root systems are a must to prevent punctures in the base layer. Once the surface water seeps into the middle permeable layer in flows along the non-permeable layer. The layers are graded on a slope so the water either flows off of the contaminated area or into a sump for storage.
References:
"4-26 Landfill Cap." Federal Remediation Technologies Roundtable. N.p., 7 July 2008. Web. 2 Nov. 2009. http://www.frtr.gov/matrix2/section4/4-27.html.
Pichtel, J. (2007). Fundamentals of site remediation for metal and hydrocarbon-contaminated soils. Lanham, Maryland:Government Institues.
Reible, D. (n.d.). In Situ Sediment Remediation Through Capping: Status and Research Needs. Retrieved from http://www.hsrc-ssw.org/pdf/cap-bkgd.pdf
Soil Vapor Extraction
Matthew Jacobs
2 November 2009
Soil Vapor Extraction (SVE) is a very common technology utilized globally to remove volatile constituents from contaminated sites, often from leaking underground storage tanks. SVE is also known as soil venting or vacuum extraction. Volatile compounds can be removed from the vadose zone by applying a vacuum to the soil through a series of extraction wells. Typical SVE systems consists of extraction wells, extraction piping, extraction blower, piping manifold, vapor pre-treatment, instrumentation and controls such as flow gauges, temperature sensors and vacuum gauges are typical, plus the vapor destruction unit itself (Pichtel, 2000). The removed vapors are then treated or often thermally destructed or filtered through activated carbon chambers. Highly volatile compounds such as gasoline are more easily extracted than larger less volatile compounds such as oils and diesel fuels (EPA, 2004). Therefore, the prime contaminants to be targeted by SVE systems are highly volatile, high vapor pressure petroleum hydrocarbons.
Before an SVE is installed, there are many steps to take in the evaluation process to determine if the right technology is being chosen. First of all, an initial screening is usually completed to test the potential success rate of a full system. This can be done as a pilot test on just one extraction well. If deemed successful, a full system can be designed and installed at the site. A full system usually consists of several extraction wells up to several dozen wells. The number of wells is determined by the area needing treatment. During installation, extraction wells are strategically placed to draw the greatest area of influence of each well. The soil types and contaminants of concern are thoroughly evaluated prior to well placement. Sandy and gravel soils are much better candidates for SVE systems than clay and silty areas. Sites with shallow groundwater are more prone to problems due to upwelling and low vacuum flow. If groundwater is a concern, another remediation technology should be selected. One of the most important factors to determine is the vapor pressure of the targeted contaminants. If the contaminants will easily evaporate, then the vacuum will be able to pull the compounds from the vadose zone successfully. If the contaminants have lower vapor pressures, the SVE will not be as effective. Compounds such as Methyl t-butyl ether, benzene, toluene, and ethylbenzene have higher vapor pressures and are better candidates for SVE systems (EPA, 2004). Therefore, the best environmental settings to utilize SVE systems have deeper groundwater, highly volatile, easily evaporative organic compounds, and sandy or gravel soil.
Each extraction well is then tied into the vapor destruction unit by piping, often pvc piping placed a few feet below grade. Once up and running, the system can be modified to best reach maximum extraction. As the contaminants are removed, the concentration will decrease. Flow rates may need to be increased as the contaminant concentrations drop. SVE systems can also be complemented by other technologies such as air sparging and dual phase extraction systems for vadose and groundwater treatment.
References:
EPA. 2004. How to Evaluate Alternative Cleanup Technologies for Underground Storage Tank Sites. EPA 510-R-04-002. http://www.epa.gov/swerust1/pubs/tum_ch2.pdf
Lambert, Steve and Mohamad Kotob. 2000. Soil Vapor Extraction. UCSD, Chemical Engineering. http://chemelab.ucsd.edu/sve/ProjSum.htm
Pichtel, John. 2000. Fundamentals of Site Remediation. pp. 193-208.
Wetland Construction: Environmental Settings, Contaminants, and Technologies
James Jackson
2 November 2009
The construction of wetlands for environmental remediation can be used in a variety of settings including agricultural, industrial, residential and municipal operations. However, the use of a constructed wetland for remediation in these environmental settings is dependent on the available flow rate of water into the wetland and the availability of sizable land for the construction (Huddleston, et al. 2003). If the flow rate and available land requirement is satisfied it is possible to establish a wetland to remediate contaminated water as disposal occurs. For example, many municipalities have established wetlands as a means of wastewater disposal from treatment plants. Constructed wetlands are capable of remediating metals, solid wastes and organic compounds found in contaminated water (Huddleston, et al. 2003; House, et al. 1998). The technology used for the wetland construction can be considered simple, inexpensive and readily available. Based on physical and computer modeling and testing a wetland is constructed for a specific set of contaminates (Huddleston, et al. 2003). The modeling and testing determines the vegetation type, soil characteristics and the hydraulic properties that will be used for the constructed wetland (Huddleston, et al. 2003).
References:
Huddleston, George and Rodgers, John. “A Design Approach for Constructed Wetlands for Storm Water and Point-Source Wastewater Treatment” 2003. Proceedings of the 2003 Georgia Water Resource Conference. Retrieved from the World Wide Web November 1, 2009 at http://cms.ce.gatech.edu/gwri/uploads/proceedings/2003/Huddleston%20and%20Rodgers.PDF
House, C.H., Bergmann, B.A., Stomp, A.M. and Frederick, D.J. “Combining constructed wetlands and aquatic and soil filters for reclamation and reuse of water” 1998. Retrieved from the World Wide Web November 1, 2009 at http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VFB-3VF1HP2-4&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1074979782&_rerunOrigin=sch
Flushing organics from soil using surfactants
Arti Jain
2 November 2009
A surfactant is briefly defined as a material that can greatly reduce the surface tension of water when used in very low concentrations.
A particular type of molecular structure performs as a surfactant. This molecule is made up of a water soluble (hydrophilic) and a water insoluble (hydrophobic) component.
How successful is the soil flushing is dependent upon the polarity / solubility of the contaminant. Highly soluble ones can be easily removed by just flushing with water. But organic compounds which are hydrophobic need a surfactant for remediation process. The contaminants for which surfactant may be required include aromatic compounds in petroleum and fuel residue, chlorinated compounds in commercial solvents like trichloroethene and chemicals no longer produced in the United States, for example DDT(chlorinated pesticides).
Several factors can influence the efficiency of soil flushing with surfactants. Groundwater that is too hard can lower the effectiveness of a surfactant. Surfactants can adsorb onto clay fractions, reducing their availability. Removal of the surfactant from the recovered water from flushing can be difficult and lead to high consumption rates. pH, ionic strength, particle size, density of soil are also critical factors. The hydraulic conductivity of soil, recovery of applied surfactant, how efficiently the soil can be flooded with the flushing solution is a critical factor. Too quick biodegradation can inactivate the surfactant although some degradability is required to avoid accumulation.
The main factors that should be considered when selecting surfactants include effectiveness, cost, public and regulatory perception, biodegradability and degradation products, toxicity to humans, animals and plants and ability to recycle. Though, the first consideration is that the surfactants are efficient in removing the contaminant.
References:
American Academy of Environmental Engineers ( AAEE), 1993. In: Anderson, W.C. (Ed.), Soil washing/soil flushing, Innovative Site Remediation, vol. 3, WASTEC.
Pichtel, John. Fundamentals of Site Remediation. Maryland: Government Institutes, 2007. Print.
Schafer, Andrea. Natural Organics Removal Using Membranes: Principles, Performance, and Cost. Boca Raton: CRC, 2001. Print.
"Surfactant - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 1 Nov. 2009..
Dwarakanath, V., Kostarelos, K., Shotts, D., Pope, G., & Wade, W. (1999). Anionic surfactant remediation of soil columns contaminated by nonaqueous phase liquids . Journal of Contaminant Hydrology, 38(4), 465-488.
Treatment of Contaminated Groundwater by Air Stripping – Considerations of Environmental Settings and Contaminants in Application of the Technology
Curtis Kempton
2 November 2009
Air stripping is a groundwater treatment technology applied in situations where volatile organic compounds (VOCs) or some semivolatiles have been released into soil and have contaminated the groundwater. Because air stripping is a mass transfer technology, transferring the contaminants from water to air without destroying them, its application is extremely dependent on the properties of the contaminant. There are also factors associated with general environmental settings that must be considered.
Air stripping has been utilized to remove contaminants such as BTEX, Chloroethane, TCE, DCE, and PCE. The Henry’s law constant is used to determine if air stripping is a good candidate treatment technology for the contaminant in question. Henry’s Law constant is a temperature dependent property of the contaminant that is a measure of how well the contaminant will separate from the water into the air. A higher Henry’s Law constant means easier separation into the air from the contaminated water. In general, air stripping is only effective for VOC or semivolatile contaminants with a Henry’s Law constant greater than 0.01 m3-atm/mol. (FRTR, 2007).
Because Henry’s Law constant is temperature dependent, the ambient temperature is an environmental factor that must be considered. Heating of either the water (CPEO, 2002) or the air (Pichtel, 2007) in the air stripping process may be done to increase the effectiveness of the process. This practice, however, is very energy intensive and costly.
References:
Center for Public Environmental Oversight. (2002). Technology tree: Air stripping. Retrieved October 31, 2009, from http://www.cpeo.org/techtree/ttdescript/airstr.htm
Federal Remediation Technologies Roundtable. (2007). Remediation technologies screening matrix and reference guide, version 4.0: Section 4.45 air stripping. Retrieved October 31, 2009, from http://www.frtr.gov/matrix2/section4/4-46.html
Pichtel, J. (2007). Fundamentals of site remediation (2nd ed. ed.). U.S.A.: Government Institutes.
Air Sparging
Jaime Hernandez
3 November 2009
Air sparging is a system which injects atmospheric air into the subsurface, allowing for hydrocarbons to return to a vapor phase. This type of application is also called “in situ air stripping” and “in situ volatilization” (OUST, 2009). The soil vapors are extracted and processed through different remedial technologies, such as thermal oxidation or carbon adsorption. Air sparging is commonly used in “lighter gasoline constituents“ remediation projects, because of the increased ability to transfer from dissolved phase to gaseous phase (OUST, 2009). “The effectiveness of air sparging depends primarily on two factors:1. Vapor/dissolved phase partitioning of the constituents determines the equilibrium distribution of a constituent between the dissolved phase and the vapor phase. Vapor/dissolved phase partitioning is, therefore, a significant factor in determining the rate at which dissolved constituents can be transferred to the vapor phase. 2. Permeability of the soil determines the rate at which air can be injected into the saturated zone. It is the other significant factor in determining the mass transfer rate of the constituents from the dissolved phase to the vapor phase.” (OUST, 2009)Air sparging may also aid in aerobic biodegradation processes. As decomposition progresses, subsurface oxygen concentration may be depleted. “Air, oxygen, or other oxygen source (e.g., hydrogen peroxide, ozone) may need to be added to the infiltration water.” (Pitchel, 2007, p. 284) Atmospheric air may be injected by sparging mechanisms and therefore replenish oxygen for biodegradation to continue. The sparger abatement system has also been designed for geothermal non-condensable gas (NCG) applications. In this case, the contaminated air is sparged through the treatment liquid. A sparger system is currently installed to abate H2S using a chemical oxidant in a pH controlled cooling water at geothermal facilities in Imperial County (CalEnergy, 2005). The sparging pipes run the length of the cooling tower basin. Non-condensable gas is cooled to approximately 160 F via a heat exchanger prior to entering the sparging system. The NCG stream bubbled in the cooling water is oxidized to sulfuric acid by oxidizing agents (CalEnergy 2005). Abatement efficiency for this type of sparger system is calculated to be 80%.
References:
Air Sparging Office of Underground Storage Tanks (OUST) US EPA. (n.d.). U.S. Environmental Protection Agency. Retrieved November 3, 2009, from http://www.epa.gov/oust/cat/airsparg
Imperial County. Air Pollution Control District. (2005, April) CalEnergy Leathers Permit 1927F Review. El Centro, CA: Cesar Flores.
Pichtel, J. (2007). Fundamentals of Site Remediation for Metal- and Hydrocarbon-contaminated Soils (null ed.). Rockville: Government Institutes.
Bioreactors
Makasha Hibbeler
4 November 2009
Once you’ve had a spill, leak, breach of containment or release of any kind of hazardous or toxic substance, you must protect the groundwater.[1] When deciding on what type of pump and treatment method you need, you must first take into consideration site characteristics and the contaminant type.[3] The first step should be to fully contain the release. To know if the containment method you have chosen is effective and holding the released materials in place, groundwater monitoring needs to be done. Once you have established the plume where the groundwater/soil is contaminated and have outlined the areas that are non-contaminated, then you can decide on what type of treatment is most effective and efficient to the desired level of treatment.[3]Bioreactors can be used in groundwater, wastewater and soil remediation. It is an Ex Situ process yet the bioreactor can be located both on and off the site. In Situ processes of the bioreactor maybe used though. The types of reactors can be either anaerobic (Oxygen is not needed or present, an example of this process would be used for a landfill) or aerobic (Oxygen is required, an example of this process would be removing Mercury from wastewater) processes but the reactors are primarily aerobic. The bioreactors are extremely diversified when it comes to their uses. They can be used on both organic and inorganic material ranging from human domestic waste to toxic organic waste and heavy metal contamination. [2]
References:
1 Khan, “An Overview and Analysis of site remediation technologies”, Journal of Environmental Management yr:2004 vol:71 iss:2 pg:952
2 Nyer, “Groundwater Treatment Technology”, [0-471-28414-9], 19923
3 Pichtel, J. (2007). Fundamentals of site remediation for metal and hydrocarbon-contaminated soils. Lanham, Maryland: Government Institues
Environmental Settings for use of Granular Activated Carbon
Cherie Jourdan
31Oct09
Granular Activated Carbon (GAC) is most effective at the removal of pesticides, volatile organic compounds (VOCs), chlorine, benzene, trihalomethanes, radon and multiple other man made chemicals typically found in our tap water. If properly developed, GAC can also remove some heavy metals, Giardia and Cryptosporidium.GAC filters are not successful at removing sediment and particulates therefore they are often in conjunction with sediment filters. GAC filters would not be found in a system that is primarily looking to remove such items as sediment and particulates.GAC Technologies are often found in contaminated river beds where other remediation technologies have been deemed too complicated or too expensive. In a river bed, the GAC will have the opportunity to absorb contaminants on a continuous basis.Even more common than a contaminated river bed, GAC is often found in a filter column treating unfavorable tap water. GAC is often found in systems that can treat tap water on a slow continuous basis rather than a fast acting, immediate one.
References:
Activated Carbon Water Filters and Purification (Granular/Granulated and Carbon Block). (n.d.). Retrieved October 31, 2009, from http://www.home-water-purifiers-and-filters.com/carbon-water-filter.php
Kvech, S., & Tull, E. (n.d.). Activated Carbon. Retrieved October 31, 2009, from http://www.cee.vt.edu/ewr/environmental/teach/wtprimer/carbon/sketcarb.html
Environmental Settings for use of Subsurface Barriers: Slurry Walls
Carin Kelley
2November 2009
Subsurface barriers like slurry walls can provide a barrier to contain hazardous chemical contaminants from migrating or prevent mixing of contaminant groundwater with uncontaminated groundwater and act as a filter to lower acidic pH levels in the groundwater, or be used to change the direction of groundwater flow.Slurry walls are made up of soil, bentonite clay, and water that provide low permeability at a low cost. They can be used in all types of soil including those below the groundwater table. However, the soil bentonite cannot withstand strong acids, bases, salts and/or organic contaminants. Under those chemical conditions, other bentonite mixtures are utilized, such as; cement bentonite, attapulgite, or slurry geomembrane composite which are generally used as barriers for landfill leachates and salt water.The construction of the slurry wall depends on the chemical properties. Near the groundwater table, the slurry wall will essentially be ‘hanging’ to capture the floating contaminants with low densities such as gases, oils, or fuels. For contaminants that are soluble, such as; metals, organics, or salts, a slurry wall that is connected to bedrock is more feasible to utilize. The physical properties of a common slurry wall can be placed as deep as 100 feet, a thickness of 2 to 4 feet, with a hydraulic conductivity of 1 x 10-6 centimeters per second. Most often, for effective pollution control, the slurry wall is connected to bedrock 2 to 3 feet.
References:
FRTR Remediation Technologies Screening Matrix and Reference Guide, Version 4.0 (n.d). GW Containment Remediation Technology 4.52 Physical Barriers. Retrieved 1 November 2009, from http://www.frtr.gov/matrix2/section4/4-53.html
U.S. EPA (17 July 2009). Engineering Technical Support Center (ETSC). Retrieved 30 October 2009, from http://www.epa.gov/nrmrl/lrpcd/rr/etsc/physchem.htm
Welcome to Slurry Wall.Com (2005). Detailed Specification for Slurry Walls Including Off-Site Disposal of Excess Slurry Off-Site Materials for Slurry Wall Backfill. Retrieved 30 October 2009, from http://www.slurrywall.com/slurry-wall-specifications/default.asp
Welcome to Slurry Wall.Com (2005). Slurry Wall, Cutoff Wall, Slurry Trench Technology Overview. Retrieved 1 November 2009, from http://www.slurrywall.com/slurry-walls-technology/default.asp#WHAT-ARE-SLURRY-WALLS
Capping Systems
Arell Gray
2 November 2009
One relatively inexpensive way to control the infiltration of surface water to a contamination plume is to build a capping system. The purpose of the cap is to block infiltrating surface water and to prevent the spread of the contamination to the groundwater or to stop the emission of subsurface gasses, it also provides a stable surface to cover the contamination and improves the general looks of the site. Though capping does not actually remove any contamination from the soil, it keeps the contamination local and prevents further spreading of the plume. In many instances, excavation of the contaminated soil takes place prior to the capping to even further insure the prevention of plume migration.A variety of capping materials can be used, from natural soils to synthetic liners, and they can be designed with varying complexity from single layer caps to multilayer capping systems. The different methods used when installing capping systems vary due to several site condition variables, such as the chemistry of the contaminate, climate, type of soil, financial constraints, or future plans for the site. When these conditions are all factored in, a decision can be made about the capping material and the complexity of the system.
Capping Materials
Natural- Natural barriers include fine grained soils like clays and clayey silts. When locally available natural capping materials can be very cheap in comparison with synthetic materials. Natural barriers also are very durable and can work effectively for many years. The process is fairly simple, just lay out the capping material and compact it using heavy machinery.Synthetic membranes- Many non-permeable synthetic materials exist and are very effective at keeping contamination from spreading. The wide variety of materials make it possible to contain a wide variety of contaminates. Once a surface is prepared over the contaminated soil, layers of synthetic membranes are placed down and sealed together. These synthetic membranes usually come in rolls of sheeting 20-140 mils, widths of 15-100 feet and lengths of 180-840 feet. The number of layers and what they are composed of is determined due to the site conditions. Extra care must be taken when installing the sheeting because any tear or puncture compromises the integrity of the cap. Another concern is the vegetation that grows on the cap, plants that have deep driving roots may also puncture the cap.
Synthetic Capping Materials include;
*HDPE (high density polyethylene)*VLDPE (very low density polyethylene)*PVC (Polyvinyl Chloride)*CSPE (chlorosulfonated polyethylene)*EIA (ethylene interpolymer alloy)*urethane*polypropylene*proprietary formulationsPavement- Asphalt or concrete, though unsightly, make an effective and easy cap for temporary capping of large areas.Multilayer systemsMany caps are composed of multiple layers. The base of which is a non-permeable or low-permeability layer either natural or synthetic. The middle layer is a permeable layer like sand or gravel and the top layer is made of vegetated native uncontaminated topsoil. The vegetation keeps the cap from eroding and provides aesthetic value, however vegetation with shallow root systems are a must to prevent punctures in the base layer. Once the surface water seeps into the middle permeable layer in flows along the non-permeable layer. The layers are graded on a slope so the water either flows off of the contaminated area or into a sump for storage.
References:
"4-26 Landfill Cap." Federal Remediation Technologies Roundtable. N.p., 7 July 2008. Web. 2 Nov. 2009. http://www.frtr.gov/matrix2/section4/4-27.html.
Pichtel, J. (2007). Fundamentals of site remediation for metal and hydrocarbon-contaminated soils. Lanham, Maryland:Government Institues.
Reible, D. (n.d.). In Situ Sediment Remediation Through Capping: Status and Research Needs. Retrieved from http://www.hsrc-ssw.org/pdf/cap-bkgd.pdf
Soil Vapor Extraction
Matthew Jacobs
2 November 2009
Soil Vapor Extraction (SVE) is a very common technology utilized globally to remove volatile constituents from contaminated sites, often from leaking underground storage tanks. SVE is also known as soil venting or vacuum extraction. Volatile compounds can be removed from the vadose zone by applying a vacuum to the soil through a series of extraction wells. Typical SVE systems consists of extraction wells, extraction piping, extraction blower, piping manifold, vapor pre-treatment, instrumentation and controls such as flow gauges, temperature sensors and vacuum gauges are typical, plus the vapor destruction unit itself (Pichtel, 2000). The removed vapors are then treated or often thermally destructed or filtered through activated carbon chambers. Highly volatile compounds such as gasoline are more easily extracted than larger less volatile compounds such as oils and diesel fuels (EPA, 2004). Therefore, the prime contaminants to be targeted by SVE systems are highly volatile, high vapor pressure petroleum hydrocarbons.
Before an SVE is installed, there are many steps to take in the evaluation process to determine if the right technology is being chosen. First of all, an initial screening is usually completed to test the potential success rate of a full system. This can be done as a pilot test on just one extraction well. If deemed successful, a full system can be designed and installed at the site. A full system usually consists of several extraction wells up to several dozen wells. The number of wells is determined by the area needing treatment. During installation, extraction wells are strategically placed to draw the greatest area of influence of each well. The soil types and contaminants of concern are thoroughly evaluated prior to well placement. Sandy and gravel soils are much better candidates for SVE systems than clay and silty areas. Sites with shallow groundwater are more prone to problems due to upwelling and low vacuum flow. If groundwater is a concern, another remediation technology should be selected. One of the most important factors to determine is the vapor pressure of the targeted contaminants. If the contaminants will easily evaporate, then the vacuum will be able to pull the compounds from the vadose zone successfully. If the contaminants have lower vapor pressures, the SVE will not be as effective. Compounds such as Methyl t-butyl ether, benzene, toluene, and ethylbenzene have higher vapor pressures and are better candidates for SVE systems (EPA, 2004). Therefore, the best environmental settings to utilize SVE systems have deeper groundwater, highly volatile, easily evaporative organic compounds, and sandy or gravel soil.
Each extraction well is then tied into the vapor destruction unit by piping, often pvc piping placed a few feet below grade. Once up and running, the system can be modified to best reach maximum extraction. As the contaminants are removed, the concentration will decrease. Flow rates may need to be increased as the contaminant concentrations drop. SVE systems can also be complemented by other technologies such as air sparging and dual phase extraction systems for vadose and groundwater treatment.
References:
EPA. 2004. How to Evaluate Alternative Cleanup Technologies for Underground Storage Tank Sites. EPA 510-R-04-002. http://www.epa.gov/swerust1/pubs/tum_ch2.pdf
Lambert, Steve and Mohamad Kotob. 2000. Soil Vapor Extraction. UCSD, Chemical Engineering. http://chemelab.ucsd.edu/sve/ProjSum.htm
Pichtel, John. 2000. Fundamentals of Site Remediation. pp. 193-208.
Wetland Construction: Environmental Settings, Contaminants, and Technologies
James Jackson
2 November 2009
The construction of wetlands for environmental remediation can be used in a variety of settings including agricultural, industrial, residential and municipal operations. However, the use of a constructed wetland for remediation in these environmental settings is dependent on the available flow rate of water into the wetland and the availability of sizable land for the construction (Huddleston, et al. 2003). If the flow rate and available land requirement is satisfied it is possible to establish a wetland to remediate contaminated water as disposal occurs. For example, many municipalities have established wetlands as a means of wastewater disposal from treatment plants. Constructed wetlands are capable of remediating metals, solid wastes and organic compounds found in contaminated water (Huddleston, et al. 2003; House, et al. 1998). The technology used for the wetland construction can be considered simple, inexpensive and readily available. Based on physical and computer modeling and testing a wetland is constructed for a specific set of contaminates (Huddleston, et al. 2003). The modeling and testing determines the vegetation type, soil characteristics and the hydraulic properties that will be used for the constructed wetland (Huddleston, et al. 2003).
References:
Huddleston, George and Rodgers, John. “A Design Approach for Constructed Wetlands for Storm Water and Point-Source Wastewater Treatment” 2003. Proceedings of the 2003 Georgia Water Resource Conference. Retrieved from the World Wide Web November 1, 2009 at http://cms.ce.gatech.edu/gwri/uploads/proceedings/2003/Huddleston%20and%20Rodgers.PDF
House, C.H., Bergmann, B.A., Stomp, A.M. and Frederick, D.J. “Combining constructed wetlands and aquatic and soil filters for reclamation and reuse of water” 1998. Retrieved from the World Wide Web November 1, 2009 at http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VFB-3VF1HP2-4&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1074979782&_rerunOrigin=sch
Flushing organics from soil using surfactants
Arti Jain
2 November 2009
A surfactant is briefly defined as a material that can greatly reduce the surface tension of water when used in very low concentrations.
A particular type of molecular structure performs as a surfactant. This molecule is made up of a water soluble (hydrophilic) and a water insoluble (hydrophobic) component.
How successful is the soil flushing is dependent upon the polarity / solubility of the contaminant. Highly soluble ones can be easily removed by just flushing with water. But organic compounds which are hydrophobic need a surfactant for remediation process. The contaminants for which surfactant may be required include aromatic compounds in petroleum and fuel residue, chlorinated compounds in commercial solvents like trichloroethene and chemicals no longer produced in the United States, for example DDT(chlorinated pesticides).
Several factors can influence the efficiency of soil flushing with surfactants. Groundwater that is too hard can lower the effectiveness of a surfactant. Surfactants can adsorb onto clay fractions, reducing their availability. Removal of the surfactant from the recovered water from flushing can be difficult and lead to high consumption rates. pH, ionic strength, particle size, density of soil are also critical factors. The hydraulic conductivity of soil, recovery of applied surfactant, how efficiently the soil can be flooded with the flushing solution is a critical factor. Too quick biodegradation can inactivate the surfactant although some degradability is required to avoid accumulation.
The main factors that should be considered when selecting surfactants include effectiveness, cost, public and regulatory perception, biodegradability and degradation products, toxicity to humans, animals and plants and ability to recycle. Though, the first consideration is that the surfactants are efficient in removing the contaminant.
References:
American Academy of Environmental Engineers ( AAEE), 1993. In: Anderson, W.C. (Ed.), Soil washing/soil flushing, Innovative Site Remediation, vol. 3, WASTEC.
Pichtel, John. Fundamentals of Site Remediation. Maryland: Government Institutes, 2007. Print.
Schafer, Andrea. Natural Organics Removal Using Membranes: Principles, Performance, and Cost. Boca Raton: CRC, 2001. Print.
"Surfactant - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 1 Nov. 2009.
Dwarakanath, V., Kostarelos, K., Shotts, D., Pope, G., & Wade, W. (1999). Anionic surfactant remediation of soil columns contaminated by nonaqueous phase liquids . Journal of Contaminant Hydrology, 38(4), 465-488.
Treatment of Contaminated Groundwater by Air Stripping – Considerations of Environmental Settings and Contaminants in Application of the Technology
Curtis Kempton
2 November 2009
Air stripping is a groundwater treatment technology applied in situations where volatile organic compounds (VOCs) or some semivolatiles have been released into soil and have contaminated the groundwater. Because air stripping is a mass transfer technology, transferring the contaminants from water to air without destroying them, its application is extremely dependent on the properties of the contaminant. There are also factors associated with general environmental settings that must be considered.
Air stripping has been utilized to remove contaminants such as BTEX, Chloroethane, TCE, DCE, and PCE. The Henry’s law constant is used to determine if air stripping is a good candidate treatment technology for the contaminant in question. Henry’s Law constant is a temperature dependent property of the contaminant that is a measure of how well the contaminant will separate from the water into the air. A higher Henry’s Law constant means easier separation into the air from the contaminated water. In general, air stripping is only effective for VOC or semivolatile contaminants with a Henry’s Law constant greater than 0.01 m3-atm/mol. (FRTR, 2007).
Because Henry’s Law constant is temperature dependent, the ambient temperature is an environmental factor that must be considered. Heating of either the water (CPEO, 2002) or the air (Pichtel, 2007) in the air stripping process may be done to increase the effectiveness of the process. This practice, however, is very energy intensive and costly.
References:
Center for Public Environmental Oversight. (2002). Technology tree: Air stripping. Retrieved October 31, 2009, from http://www.cpeo.org/techtree/ttdescript/airstr.htm
Federal Remediation Technologies Roundtable. (2007). Remediation technologies screening matrix and reference guide, version 4.0: Section 4.45 air stripping. Retrieved October 31, 2009, from http://www.frtr.gov/matrix2/section4/4-46.html
Pichtel, J. (2007). Fundamentals of site remediation (2nd ed. ed.). U.S.A.: Government Institutes.
Air Sparging
Jaime Hernandez
3 November 2009
Air sparging is a system which injects atmospheric air into the subsurface, allowing for hydrocarbons to return to a vapor phase. This type of application is also called “in situ air stripping” and “in situ volatilization” (OUST, 2009). The soil vapors are extracted and processed through different remedial technologies, such as thermal oxidation or carbon adsorption. Air sparging is commonly used in “lighter gasoline constituents“ remediation projects, because of the increased ability to transfer from dissolved phase to gaseous phase (OUST, 2009). “The effectiveness of air sparging depends primarily on two factors:1. Vapor/dissolved phase partitioning of the constituents determines the equilibrium distribution of a constituent between the dissolved phase and the vapor phase. Vapor/dissolved phase partitioning is, therefore, a significant factor in determining the rate at which dissolved constituents can be transferred to the vapor phase. 2. Permeability of the soil determines the rate at which air can be injected into the saturated zone. It is the other significant factor in determining the mass transfer rate of the constituents from the dissolved phase to the vapor phase.” (OUST, 2009)Air sparging may also aid in aerobic biodegradation processes. As decomposition progresses, subsurface oxygen concentration may be depleted. “Air, oxygen, or other oxygen source (e.g., hydrogen peroxide, ozone) may need to be added to the infiltration water.” (Pitchel, 2007, p. 284) Atmospheric air may be injected by sparging mechanisms and therefore replenish oxygen for biodegradation to continue. The sparger abatement system has also been designed for geothermal non-condensable gas (NCG) applications. In this case, the contaminated air is sparged through the treatment liquid. A sparger system is currently installed to abate H2S using a chemical oxidant in a pH controlled cooling water at geothermal facilities in Imperial County (CalEnergy, 2005). The sparging pipes run the length of the cooling tower basin. Non-condensable gas is cooled to approximately 160 F via a heat exchanger prior to entering the sparging system. The NCG stream bubbled in the cooling water is oxidized to sulfuric acid by oxidizing agents (CalEnergy 2005). Abatement efficiency for this type of sparger system is calculated to be 80%.
References:
Air Sparging Office of Underground Storage Tanks (OUST) US EPA. (n.d.). U.S. Environmental Protection Agency. Retrieved November 3, 2009, from http://www.epa.gov/oust/cat/airsparg
Imperial County. Air Pollution Control District. (2005, April) CalEnergy Leathers Permit 1927F Review. El Centro, CA: Cesar Flores.
Pichtel, J. (2007). Fundamentals of Site Remediation for Metal- and Hydrocarbon-contaminated Soils (null ed.). Rockville: Government Institutes.
Bioreactors
Makasha Hibbeler
4 November 2009
Once you’ve had a spill, leak, breach of containment or release of any kind of hazardous or toxic substance, you must protect the groundwater.[1] When deciding on what type of pump and treatment method you need, you must first take into consideration site characteristics and the contaminant type.[3] The first step should be to fully contain the release. To know if the containment method you have chosen is effective and holding the released materials in place, groundwater monitoring needs to be done. Once you have established the plume where the groundwater/soil is contaminated and have outlined the areas that are non-contaminated, then you can decide on what type of treatment is most effective and efficient to the desired level of treatment.[3]Bioreactors can be used in groundwater, wastewater and soil remediation. It is an Ex Situ process yet the bioreactor can be located both on and off the site. In Situ processes of the bioreactor maybe used though. The types of reactors can be either anaerobic (Oxygen is not needed or present, an example of this process would be used for a landfill) or aerobic (Oxygen is required, an example of this process would be removing Mercury from wastewater) processes but the reactors are primarily aerobic. The bioreactors are extremely diversified when it comes to their uses. They can be used on both organic and inorganic material ranging from human domestic waste to toxic organic waste and heavy metal contamination. [2]
References:
1 Khan, “An Overview and Analysis of site remediation technologies”, Journal of Environmental Management yr:2004 vol:71 iss:2 pg:952
2 Nyer, “Groundwater Treatment Technology”, [0-471-28414-9], 19923
3 Pichtel, J. (2007). Fundamentals of site remediation for metal and hydrocarbon-contaminated soils. Lanham, Maryland: Government Institues
Sunday, October 11, 2009
Vinyl Chloride General Chemisty and Use - Team Delta - Damein Watt Repost
General Chemistry and Use
Vinyl chloride is the organic compound with the formula C2H3Cl. Vinyl chloride burns easily and it is not stable at high temperatures. It is a manufactured compound that does not occur naturally. Vinyl can be produced when other substances such as trichloroethane, trichloroethylene, and tetrachloroethylene are degrade in the environment. This colorless compound is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC).
Vinyl chloride, also known as chloroethene, is a halogenated aliphatic hydrocarbon with an empirical formula of C2H3Cl and a molecular weight of 62.5. It is a colorless gas with a mild sweetish odor, a melting point of -153.71 °C, a boiling point of -13.8°C, a specific gravity of 0.9121 g/mL, and a vapor pressure of 2580 torr. The odor threshold for vinyl chloride is 3,000 ppm. Vinyl chloride is slightly soluble in water and is quite flammable. The vapor pressure for vinyl chloride is 2,600 mm Hg at 25 °C, and it has a log octanol/water partition coefficient (log Kow) of 1.36.
Production from Ethylene dichloride
The production of vinyl chloride from dichloroethylene or ethylene dichloride (EDC) consists of a series of well defined steps. Ethylene dichloride (EDC) can be produced using the direct chlorination method, oxychlorination method, or using acetylene as a feedstock. To produce vinyl chloride, ethylene dichloride is decomposed by heating the compound to 500°C at 15–30 atm (1.5 to 3 MPa) pressure, producing vinyl chloride and HCl:
ClCH2CH2Cl → CH2=CHCl + HCl
The effluent stream is then chilled using a refrigerant prior to being processed in a series of distillation towers. The last distillation tower has pure HCl going from the top and product vinyl chloride coming out of the bottom. The recycled HCl is used to produce more EDC yielding a cost efficient method of production. This method is widely used cause of the environmental and economical advantages.
References:
M. Rossberg, & Allen, D. T. (2009, Oct). Vinyl chloride [Electronic version]. In Wikipedia. Retrieved October 11, 2009, from Vinyl chloride: http://en.wikipedia.org/wiki/Vinyl_chloride
Vinyl Chloride. (2006, July). Retrieved April 3, 2009, from http://www.atsdr.cdc.gov/toxprofiles/tp20-c4.pdf: Center for Disease Control
About Vinyl and PVC. (2008, April). Retrieved April 7, 2009, fromhttp://www.vinylbydesign.com/site/page.asp?CID=1&DID=2: Vinyl in Design
Vinyl chloride is the organic compound with the formula C2H3Cl. Vinyl chloride burns easily and it is not stable at high temperatures. It is a manufactured compound that does not occur naturally. Vinyl can be produced when other substances such as trichloroethane, trichloroethylene, and tetrachloroethylene are degrade in the environment. This colorless compound is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC).
Vinyl chloride, also known as chloroethene, is a halogenated aliphatic hydrocarbon with an empirical formula of C2H3Cl and a molecular weight of 62.5. It is a colorless gas with a mild sweetish odor, a melting point of -153.71 °C, a boiling point of -13.8°C, a specific gravity of 0.9121 g/mL, and a vapor pressure of 2580 torr. The odor threshold for vinyl chloride is 3,000 ppm. Vinyl chloride is slightly soluble in water and is quite flammable. The vapor pressure for vinyl chloride is 2,600 mm Hg at 25 °C, and it has a log octanol/water partition coefficient (log Kow) of 1.36.
Production from Ethylene dichloride
The production of vinyl chloride from dichloroethylene or ethylene dichloride (EDC) consists of a series of well defined steps. Ethylene dichloride (EDC) can be produced using the direct chlorination method, oxychlorination method, or using acetylene as a feedstock. To produce vinyl chloride, ethylene dichloride is decomposed by heating the compound to 500°C at 15–30 atm (1.5 to 3 MPa) pressure, producing vinyl chloride and HCl:
ClCH2CH2Cl → CH2=CHCl + HCl
The effluent stream is then chilled using a refrigerant prior to being processed in a series of distillation towers. The last distillation tower has pure HCl going from the top and product vinyl chloride coming out of the bottom. The recycled HCl is used to produce more EDC yielding a cost efficient method of production. This method is widely used cause of the environmental and economical advantages.
References:
M. Rossberg, & Allen, D. T. (2009, Oct). Vinyl chloride [Electronic version]. In Wikipedia. Retrieved October 11, 2009, from Vinyl chloride: http://en.wikipedia.org/wiki/Vinyl_chloride
Vinyl Chloride. (2006, July). Retrieved April 3, 2009, from http://www.atsdr.cdc.gov/toxprofiles/tp20-c4.pdf: Center for Disease Control
About Vinyl and PVC. (2008, April). Retrieved April 7, 2009, fromhttp://www.vinylbydesign.com/site/page.asp?CID=1&DID=2: Vinyl in Design
Saturday, October 10, 2009
Revised Assignment 1: Vinyl Chloride for Team Delta: Andrew Watson's Blog
Transportation of Vinyl Chloride
The handling and transportation of Vinyl Chloride is important to ensure the safety of the general public and property along its route is protected. Vinyl Chloride is an extremely flammable gas and exposure to it can cause serious harm to those who encounter it unprotected. Although, Vinyl Chloride is a hazardous chemical or a hazardous waste byproduct, it can be safely transported throughout the world as long as the generator, shipper, and transporter follow rules created by national governmental agencies. In the United States, the transportation of hazardous chemicals is regulated by the Pipeline and Hazardous Materials Safety Administration (PHMSA) and the United States Department of Transportation (DOT).
Classification
Before any chemical can be transported, it must first be classified to determine if it is deemed a hazardous chemical/waste or if it is non-hazardous. This can be accomplished by looking in the Code of Federal Regulation (49 CFR) book under the proper shipping name of the chemical. Vinyl Chloride is listed as hazardous chemical (Class 2.1 flammable Gas) and to ensure safe transport, special handling and shipping requirements must be followed.
Mode of Transportation
Now that Vinyl Chloride has been determined to be a Class 2.1 flammable Gas material and needs to have special handling, a safe mode of transportation needs to be determined. The only approved modes of transportation for Vinyl Chloride are:
· Truck transport
· Cargo air craft
Forbidden modes of transportation are:
· Passenger aircraft
· Rail car
Placards
Placarding is a form of hazard communication and is the backbone of emergency response. The primary mission of DOT hazard communication is to alert the public and transportation workers of the presence of hazardous materials. Also, placarding provides visual indication to responders to a hazardous material incident. The United States Department of Transportation (US DOT) has specific requirements for placarding. Transporters, shippers, and generators must have placards that must meet the size, color, and placement required by the US DOT when shipping any hazardous chemical material or waste. An example of a placard for Vinyl Chloride is below:
Shipping papers
To become a shipper of hazardous chemicals or hazardous waste, special training and certification must be attained through agencies approved by US DOT. Shipping papers (manifest or bill of lading) are typically created and completed by the generator/shipper of hazardous chemicals/wastes and they will always be responsible for the accuracy and completeness of any manifest or documents they sign. Failure to review or falsify shipping documents can result in heavy fines AND jail time to the company and generator/shipper. So, it is imperative that the shipper/generator knows what the shipping papers requirements are and understand what the consequences are if they are not followed.
References:
PHEMSA Webpage:
http://www.phmsa.dot.gov/hazmat/regs
Matheson Tri Gas Webpage:
http://www.mathesongas.com/pdfs/msds/MAT24940.pdf
The handling and transportation of Vinyl Chloride is important to ensure the safety of the general public and property along its route is protected. Vinyl Chloride is an extremely flammable gas and exposure to it can cause serious harm to those who encounter it unprotected. Although, Vinyl Chloride is a hazardous chemical or a hazardous waste byproduct, it can be safely transported throughout the world as long as the generator, shipper, and transporter follow rules created by national governmental agencies. In the United States, the transportation of hazardous chemicals is regulated by the Pipeline and Hazardous Materials Safety Administration (PHMSA) and the United States Department of Transportation (DOT).
Classification
Before any chemical can be transported, it must first be classified to determine if it is deemed a hazardous chemical/waste or if it is non-hazardous. This can be accomplished by looking in the Code of Federal Regulation (49 CFR) book under the proper shipping name of the chemical. Vinyl Chloride is listed as hazardous chemical (Class 2.1 flammable Gas) and to ensure safe transport, special handling and shipping requirements must be followed.
Mode of Transportation
Now that Vinyl Chloride has been determined to be a Class 2.1 flammable Gas material and needs to have special handling, a safe mode of transportation needs to be determined. The only approved modes of transportation for Vinyl Chloride are:
· Truck transport
· Cargo air craft
Forbidden modes of transportation are:
· Passenger aircraft
· Rail car
Placards
Placarding is a form of hazard communication and is the backbone of emergency response. The primary mission of DOT hazard communication is to alert the public and transportation workers of the presence of hazardous materials. Also, placarding provides visual indication to responders to a hazardous material incident. The United States Department of Transportation (US DOT) has specific requirements for placarding. Transporters, shippers, and generators must have placards that must meet the size, color, and placement required by the US DOT when shipping any hazardous chemical material or waste. An example of a placard for Vinyl Chloride is below:
Shipping papers
To become a shipper of hazardous chemicals or hazardous waste, special training and certification must be attained through agencies approved by US DOT. Shipping papers (manifest or bill of lading) are typically created and completed by the generator/shipper of hazardous chemicals/wastes and they will always be responsible for the accuracy and completeness of any manifest or documents they sign. Failure to review or falsify shipping documents can result in heavy fines AND jail time to the company and generator/shipper. So, it is imperative that the shipper/generator knows what the shipping papers requirements are and understand what the consequences are if they are not followed.
References:
PHEMSA Webpage:
http://www.phmsa.dot.gov/hazmat/regs
Matheson Tri Gas Webpage:
http://www.mathesongas.com/pdfs/msds/MAT24940.pdf
Tuesday, October 6, 2009
Ground Penetrating Radar - Team Delta - Damien Watt
Investigations of contaminated soils may require use of what is known GPR or Ground Penetrating Radar. Ground penetrating radar (GPR) is a electromagnetic geophysical technique for subsurface investigation, characterization and monitoring that does not require digging or excavation. The ground penetrating radar can be deployed multiple ways. Some the methods of deployment are illustrated with the attached photos. Other methods of deployment from the surface include hand deployment or using a vehicle, placement in boreholes, between boreholes, from aircraft and from satellites. It has the highest resolution of any geophysical method for imaging the subsurface. Resolution as high as centimeter scaled resolution is possible in some cases.
GPR is widely used to locate lost utilities, perform environmental site characterization and monitoring, archaeological and forensic investigation, unexploded weapons and land mine detection, groundwater, pavement and infrastructure. The way the GPR works is similar to seismic reflection methods, the down and back pass through (or two way travel) times of the reflected, and pulse is gauged. Resolution is controlled by of the propagating electromagnetic wavelength in the ground. Resolution increases with increasing frequency and decreases with a decreasing frequency, all depending on the length of the wavelength. With approximation of radar wave velocities, the method results in vertical cross-sections that demonstrates reflecting layers of objects at depth. Depth of investigation varies from less than one meter to more than 5,400 meters depending on the media being explored. Any irregularities in the soil can either focus or scatter the wavelength depending on orientation. Scatter losses occur when the irregularity sends the wavelength in a different direction of the antenna or the electrochemical property of the soil causing low amplitude of the wavelength.
In conducting both phase I and phase II investigations GPR can be effective in finding sources of ground contamination. GPR is also very capable of to find inconsistencies in the soil as well or a boundary of Non aqueous phase liquids or NAPL in the soil due to the electrochemical properties of contaminats. GPR together with other methods such as terrain conductivity help give insight to what is going on in the ground without any digging.
Resistivity, Electomagnetic, and Radar Surveys. Groundwater Science (pp. 90, 91, 388, 389). Great Britian: Academic Press. (Original work published 2002). Retrieved October 6, 2009, from Book
Pictures (2009, October 6). Ground Penetrating Radar Surveys Retrieved October 6, 2009, from http://www.geomodel.com/; GEOmodel TM
Lawrence Conyers (2009, October 6). Ground Penetrating Radar Retrieved October 6, 2009, from http://mysite.du.edu/~lconyer/: Conyers, Lawrence, University of Denver
Ground-Penetrating Radar (2009 October). Retrieved October 6, 2009, from http://en.wikipedia.org/wiki/Ground-penetrating_radar;
SITE CONSIDERATIONS OF A PHASE 2 ESA – Team Alpha
An Environmental Site Assessment (ESA) is done to examine a property for probable contamination with hazardous materials. Phase 1 ESAs detail the geography, topography, and history of the site, with notes on any hazardous materials found during the walk-through. Phase 2 ESAs are more complex, including sampling of all materials present on the property (soil, groundwater, plants) to determine how the site will respond to or could have responded to a hazardous material contamination in the past.
There are some vital factors that must be considered during a Phase 2 ESA (list taken from Pg 134-135 of Pichtel textbook):
- Depth to groundwater and bedrock
- Soil temperature
- Moisture content
- Bulk density
- Particle size distribution and texture
- Soil structure
- Saturated hydraulic conductivity
- Unsaturated hydraulic conductivity
- Organic matter content
- Soil microbial activity
These factors are explained and expanded on below.
1.) DEPTH TO GROUNDWATER AND BEDROCK – Kyle Gilbert
Image / Table 1 – Potential for Groundwater contamination based upon depth to groundwater, can be seen at http://www.omafra.gov.on.ca/english/engineer/facts/07-035.htm (not able to print tables here)
The depth to groundwater or bedrock is crucial because it determines how far down the contaminant must travel before reaching an aquifer (Pichtel 2007). The depth will also affect the amount of time the contaminant is in contact with the soil. Where the depth is shallow, the contaminant becomes much more likely to reach groundwater (Waldron 1992). When the water and contaminants make their way to the bedrock, the time until it reaches groundwater is very short. The treatment of contaminated water primarily takes place in soil in the unsaturated zone. Shallow depth results in a short travel time for water and contaminants to move through this unsaturated zone before reaching the ground water, therefore, there is little opportunity for the treatment of water to occur.
2.) SOIL TEMPERATURE – Grinnell Duncan
Soil Temperature Regimes of the United States, retrieved from http://soils.usda.gov/use/thematic/temp_regimes.html
Soil Temperature is considered to be the mean monthly soil temperature at a specific depth, or the average of the daily high and daily low temperature for the month (NRCS 2008). Despite changing outdoor air temperatures and the effects of soil layering, ground temperatures are generally able to stay consistent at depths below 30 meters (Esen et al., 2009). In conjunction with other soil temperature sampling methods, borehole drilling can be used to measure soil temperature by lowering a thermometer down the borehole, allowing for sampling at multiple depths (Fitts 2002). It is possible for chemical reactions to change the normal breakdown process of pesticides or other chemical residues, especially in colder soil temperatures. This happens because the chemical reactions create a “thermal pan” inside the soil matrix. (NRCS 2008)
3.) MOISTURE CONTENT – Rebekah Fox-Laverty
Moisture content is important to know on a corn farm because one would have a better idea of when to plant their corn for better production. Measuring for soil moisture is difficult on a farm due to not having consistent measurement devises or scales available. Dry measuring samples and sending them to a laboratory would give the corn-farmer a better measurement of their moisture content on their farm of their soil.
Thermal conductivity is higher as the moisture content increases. Water’s thermal conductivity is high which means that the more the moisture content of soil conductivity increases, the more like water’s conductivity it will be. If the soil moisture content is high, it will take longer for the soil to heat up in the sun than dry soil and the same to become cooler once the sun has gone down. The reason it takes longer to warm and cool if the moisture content is higher is because water evaporation removes the energy from the sun before the soil has a chance to use the energy to get hot or to cool down. However, soils like clay tend to not have as high moisture content and therefore do not take as long to heat and cool.
Moisture content can affect many things from wood and cotton to corn or nutrient concentration and proteins. Moisture content can also affect composting and land treatments. Moisture content is very important in agriculture and other various industries. Detection of soil moisture can help in flood control areas, forest and farming areas, and landscape and construction sites. Detection of moisture content can help farmers monitor their crops and know when it would be a good time to plant and harvest. It can also help in the monitoring of humidity. Moisture content also affects groundwater and soil by releasing contaminants. What type of contaminants released varies on conditions and area.
These are three types of techniques that are electronic for measuring the moisture content. These measuring techniques are time domain reflectometry, capacitive sensing, and resistance sensing. Capacitive sensing relies on the humidity of the air in the area. The resistance sensing type is the most common techniques. Resistance sensing relies on the relative humidity and measures the resistance; these sensors include polymeric, metallic, or electrolytic. The most common of the sensory types is electrolytic. Sensor probes are used in time domain reflectometry technique. The probes are inserted into the soil to measure the moisture of the soil.
4.) BULK DENSITY – Rebekah Fox-Laverty
Bulk density affects contaminants and erosion rates. Soils can be measured in weight by unit volume called bulk density. Volume is considered to be the pores and solids. The bulk density of soils like minerals has a bulk density of 1.0 to 2.0. Bulk density can help compare two different soils. To get bulk density, divide the total weight by the volume (see formulas below).
There are different methods in acquiring bulk density; core method, clod method, excavation method, and radiation method. These methods are different in how the samples of soils are taken and how the volumes are established. The excavation method is used when sampling of soil is not as easily available due to lose soils. The radiation method uses the joined density of gas, liquid, and soil to determine the soil mass. The core method involves weighing the dried soil. Each of these methods helps determine the bulk density of soils.
Bulk density is important when trying to figure out the movements of moisture in soil. As the bulk density increases, the growth of roots are decreased, less exposure of air, and infiltration of water is reduced. Increased bulk density can assist in building roads and structure foundations because it reflects tight compaction of the soils beneath. Bulk density affects the movement of contaminants in both soils and tocks. Knowing the moisture content, porosity, and permeability will assist in figuring out the bulk density of soil.
5.) PARTICLE SIZE DISTRIBUTION AND TEXTURE – Josh Beutler
Particle size distribution and texture determines the mobility of contaminants within the soil structure and the type of remediation technique that may be successfully utilized. As we have seen from Dr. Edwards’ lectures, the particle size effects fluid permeability and can range from unfractured metamorphic and igneous rock (10^-16 cm^2) to gravel (10^-3 cm^2). When particle size distribution and texture is relatively constant, the primary route of flow of a contaminant is downward. When the texture is not consistent, for example when sandy soils have intermittent clay layers, the layers tend to route contaminant flow in a horizontal direction due to their relative impermeability.Permeability is a term often referred to in the Environmental Protection Agency’s evaluations for remediation technique effectiveness and intrinsic permeability directly correlates with particle size and distribution. For example, the effectiveness for soil vapor extraction remediation, also known as soil venting or vacuum extraction, has a permeability factor of greater than or equal to 10^-8 cm^2, as defined by the EPA. This indicates that soil substructure and the particle size and distribution must at least be in the range of silty sand and/or larger for soil vapor extraction to be effective. Procedures for measuring particle size and distribution are usually done through collection of soil core samples and laboratory evaluations. Assessment criteria and categorization strategies are available from the EPA or through standardized tests available from the American Society for Testing and Materials (ASTM).
6.) SOIL STRUCTURE – Ali Forouhar
The soil structure is a mix of inorganic materials, organic materials, and void spaces. Examples of inorganic materials include silt, clay, gravel, and other sediments. The void spaces can be occupied by either water or air. The texture/structure of the soil is dependent on what materials it consists of, which are an important factor in which remediation technique should be used. 
Soils with high gravel/sand soil content should also have high permeability or high hydraulic conductivity, in which case aeration or flushing technologies can be used for remediation. Clayey soils have very low hydraulic conductivity (low permeability) and do not allow vertical movement of the contaminants, which means that they may require different remediation technologies. Clay can be used as a landfill liner due to its estimated hydraulic conductivity of 10-7 centimeter/second.
Structure of Soil http://www.gf.uns.ac.rs/~wus/wus07/web6/2/soil%20structure.jpg
Void spaces and porosity help determine how water is able to move through soil particles. Higher porosity indicates higher velocity of water movement, as well as increased microbial activities. Soils with low porosity may allow for runoffs and pond formations. Organic materials contribute 1% to 50% of the total composition of soil – these are also called humus, where the organic materials are decomposed by living organisms in the soil. Decaying organic materials hold the soil particles together. Soils with low organic materials content are found mostly in arid lands. Living beings such as earthworms, fungi, nematodes, protozoa and bacteria are also major contributors to soil structures. Soil pH is also an important aspect of soil structure.
7.) SATURATED HYDRAULIC CONDUCTIVITY – Tedla Gebre
USGS defines saturated hydraulic conductivity as (see class notes session 2): “The capacity of a rock to transmit water. It is expressed as the volume of water at the existing kinematic viscosity that will move in unit time under a unit hydraulic gradient through a unit area measured at right angles to the direction of flow’’ (http://Capp.water.usgs.gov/GF). Saturation is fraction of pore space filled by a particular fluid multiple porous media (Class lecture session 2).
Saturated hydraulic conductivity is used in predicting or calculating flow to wells, lakes, rivers or storages from groundwater. It also predicts if deformation or subsidence is going to happen due to discharge or recharge.
The conductivity is used to calculate the volumetric flow, using Darcy’s Law.
K= -Q/(AI)Q is flow rate
A is the area perpendicular to the flow
I is gradient
dh/dx- Is due to higher to lower flow
K is flow constant in one or more media like clay, sand, and so on.K can be calculated from density, viscosity and gravity.
K=kρf g/μk is permeability
ρf is density
g is gravitational constant
μ is viscosity
Therefore, K is inversely proportional to viscosity μ. In most cases, saturated flow assumes homogeneity and isotropicity so that Darcy’s law applies with less complexity. To understand saturated underground flow, data of porosity and values of K tables are given.
The tables below are from Groundwater Science by Charles Fitts (2001).
Table 2.2 Typical Values of Porosity
Material n (%)
Narrowly graded silt, sand, gravel 30-50
Widely graded silt, sand, gravel 20-35
Clay, clay silt 35-60
Sand stone 5-30
Lime stone, dolomite 0-40
shale 0-10
Crystalline rock 0-10
**Will correlate the above value to hydraulic conductivity.
Table 3.1 Typical Values of Hydraulic Conductivity
Material K (cm/sec)
Gravel 10-1 to 100
Clean sand 10-4 to 1
Silt sand 10-5 to 10-1
Silt 10-7 to 10-3
Glacial till 10-10 to 10-6
Clay 10-10 to 10-6
Shale 10-14 to 10-8
From the above data, the conductivity and pore sizes determine the flow including the media and the content of liquid in the pores. Unlike unsaturated hydraulic conductivity, saturated conductivity is constant because the water content stays the same. The pore water pressure does not vary with volumetric water content θ (Fitts 2001).
For more reading I found this site: http://soils.usda.gov/technical/technotes/note6.html
8.) UNSATURATED HYDRAULIC CONDUCTIVITY – Sachie Dale
Unsaturated hydraulic conductivity is used to measure or predict water movement through pore spaces and fractured rock when the soil and fractured rocks are unsaturated with water. The knowledge of unsaturated hydraulic conductivity helps to understand the movement and travel times of pesticides, hazards, and radioactive substances through the unsaturated zone when contamination occur. It also helps to understand the flow of nutrients through the zone.
These are many techniques and methods to measure unsaturated hydraulic conductivity.Here are some examples:
· Steady-State Centrifuge Method
· Capillary Bundle Model
· Infiltration Tests
· Constant Flux and Crust Methods
9.) ORGANIC MATTER CONTENT – Jamie Ekholm
Organic matter plays an important role in the ability of a contaminant to move through the vadose zone and eventually into the phreatic zone. A large portion of what is considered soil organic matter is made up of mainly plant and animal material that has broken down over time. This material is called humus. There are other organic components of the soil (such as polysaccharides); however, these constituents are rather short-lived due to microbial breakdown.
There is a huge variety of different organic molecules that make up what is considered humus. Overall, these chemicals are found to have a considerable cation exchange capacity (CEC). CEC gives organic matter the ability to both absorb and exchange cations.
Organic matter also possesses anion exchange capacity, though to a lesser degree than CEC. Having both positive and negative charges is quite advantageous from a contaminant capture standpoint. This is especially true with many negatively-charged metal complexes as well as positively charged metal ions. The organic molecules that make up humus are also non-polar to some degree like most organic molecules. This means that humus has the ability to capture many different organic contaminants such as pesticides, organic solvents, and fuels.
10.) SOIL MICROBIAL ACTIVITY – Morgan Bliss
The microbial activity present in soil can assist in decreasing the contaminant load of soil. For instance, a highly active (aerobic or anaerobic) group of microorganisms present in the soil may allow for faster degradation of contaminants like hydrocarbons, metals, and petrochemical residues (Pichtel 2007). Microbial activity can consist of both bacteria and fungi that are able to break down contaminants and use them as a food/metabolic source.
You can estimate existing soil microbial activity by measuring the soil gas oxygen and/or carbon dioxide composition. Oxygen concentrations are generally a better indicator of microbial activity; because carbon dioxide levels can be affected by other aspects of the soil (precipitation or dissolution of carbonate rock can cause increased levels of carbon dioxide in the soil). In a soil gas survey, if you find elevated carbon dioxide and lowered oxygen levels as compared to background soil levels, it can indicate that biological activity is present in the soil. If you find that there are decreased oxygen or carbon dioxide levels in the soil of concern as compared to background soil levels, it may indicate that microbiological activity has been limited or inhibited by the site. This limitation or inhibition can be due to increased toxicity of the soil as well as insufficient water content or elevated temperatures (Hyman and Dupont 2001).
REFERENCES:
Pichtel, John. (2007) Fundamentals of Site Remediation, 2nd Edition. Toronto: Government Institutes.
Fitts, Charles R. (2002) Groundwater Science. London: Academic Press, an imprint of Elsevier.
Depth to Groundwater and Bedrock
Waldron, Acie C. Ohio Cooperative Extension Service – Ohio State University. (1992) Bulletin 820: Pesticides and Groundwater Contamination. Retrieved October 2, 2009. http://ohioline.osu.edu/b820/b820_8.html
Pichtel, John. (2007) Fundamentals of Site Remediation, 2nd Edition. Toronto: Government Institutes.
Fitts, Charles R. (2002) Groundwater Science. London: Academic Press, an imprint of Elsevier.
Depth to Groundwater and Bedrock
Waldron, Acie C. Ohio Cooperative Extension Service – Ohio State University. (1992) Bulletin 820: Pesticides and Groundwater Contamination. Retrieved October 2, 2009. http://ohioline.osu.edu/b820/b820_8.html
Soil Temperature
Esen, H., Inalli, M., & Esen, Y. (2009). Temperature distributions in boreholes of a vertical ground-coupled heat pump system. Renewable Energy, 34(12), 2672-2679.
“Part 618: Soil Properties and Qualities.” United States Department of Agriculture – National Resources Conservation Service (NRCS) Website. National Soil Survey Handbook (NSSH) Online. Accessed October 6, 2009. http://soils.usda.gov/technical/handbook/contents/part618.html
Esen, H., Inalli, M., & Esen, Y. (2009). Temperature distributions in boreholes of a vertical ground-coupled heat pump system. Renewable Energy, 34(12), 2672-2679.
“Part 618: Soil Properties and Qualities.” United States Department of Agriculture – National Resources Conservation Service (NRCS) Website. National Soil Survey Handbook (NSSH) Online. Accessed October 6, 2009. http://soils.usda.gov/technical/handbook/contents/part618.html
Moisture Content and Bulk Density
Peters, John. On-Farm Moisture Testing of Corn Soilage, Retrieved October 1, 2009. http://www.uwex.edu/ces/crops/uwforage/CSMoistTest.htm.
Cook, David R. Ask a Scientist; Soil Moisture Content. Retrieved October 2, 2009. http://www.newton.dep.anl.gov/askasci/wea00/wea00105.htm.
Table D-4: Operating Parameters: Measurement Procedures and Potential Effects on Treatment Cost or Performance. Retrieved October 4, 2009. http://www.frtr.gov/matrix2/appd_d/appd_d_tab4_fr.html.
Moisture Meter, Humidity Sensor. January 2007. Retrieved October 4, 2009 http://www.electronics-manufacturers.com/info/sensors-and-detectors/moisture-meter-humidity-sensor.html.
Bulk Density Determination. Retrieved October 4, 2009. http://www.geology.iupui.edu/research/SoilsLab/procedures/bulk/Index.htm.
EcoSystem Restoration; Analytical Methods. Physical Propertied: Bulk Density. Montana State University Bozeman; September 2004. Retrieved September 29, 2009. http://ecorestoration.montana.edu/mineland/guide/analytical/physical/bulk.htm.
Peters, John. On-Farm Moisture Testing of Corn Soilage, Retrieved October 1, 2009. http://www.uwex.edu/ces/crops/uwforage/CSMoistTest.htm.
Cook, David R. Ask a Scientist; Soil Moisture Content. Retrieved October 2, 2009. http://www.newton.dep.anl.gov/askasci/wea00/wea00105.htm.
Table D-4: Operating Parameters: Measurement Procedures and Potential Effects on Treatment Cost or Performance. Retrieved October 4, 2009. http://www.frtr.gov/matrix2/appd_d/appd_d_tab4_fr.html.
Moisture Meter, Humidity Sensor. January 2007. Retrieved October 4, 2009 http://www.electronics-manufacturers.com/info/sensors-and-detectors/moisture-meter-humidity-sensor.html.
Bulk Density Determination. Retrieved October 4, 2009. http://www.geology.iupui.edu/research/SoilsLab/procedures/bulk/Index.htm.
EcoSystem Restoration; Analytical Methods. Physical Propertied: Bulk Density. Montana State University Bozeman; September 2004. Retrieved September 29, 2009. http://ecorestoration.montana.edu/mineland/guide/analytical/physical/bulk.htm.
Particle Size Distribution and Texture
Environmental Protection Agency. (2004). How to Evaluate Alternative Cleanup Technologies For Underground Storage Tank Sites: A Guide For Corrective Action Plan Reviewers. EPA 510-R-04-002. Washington, D.C.
Environmental Protection Agency. (2004). How to Evaluate Alternative Cleanup Technologies For Underground Storage Tank Sites: A Guide For Corrective Action Plan Reviewers. EPA 510-R-04-002. Washington, D.C.
Soil structure
Environmental Protection Agency (EPA). (1995) Decision Maker’s Guide to Solid Waste Management, Volume 2. EPA 530-R-95-023. Glossary and Chapters accessed October 6, 2009 from http://www.epa.gov/waste/nonhaz/municipal/dmg2/glossary.pdf
Saturated hydraulic conductivity
ETM 523 Lecture Materials Fall 09 by Dr. David Edwards.
Natural Resources Conservation Service (NRCS) United States Department of Agriculture Website. “Saturated Hydraulic Conductivity: Water Movement Concepts and Class History.” Retrieved October 4, 2009 from http://soils.usda.gov/technical/technotes/note6.html
Unsaturated hydraulic conductivity
AGVISE Laboratory. Unsaturated Hydraulic Conductivity. Retrieved October 4, 2009, from AGVISE Laboratory. Website: http://www.agvise.com/tech_art/unsathy.php
Australian Government Connected Water. Hydraulic Conductivity Measurement. Retrieved October 4, 2009, from Australian Government Website: http://www.connectedwater.gov.au/framework/hydrometric_k.php
Daniel, D.E. & Trautwein, S.J. (1994). Hydraulic Conductivity and Waste Contaminant Transport in Soil. Philadelphia, PA.
Perkins, K.S., & Winfield, K.A. (2007). Property-Transfer Modeling to Estimate Unsaturated Hydraulic Conductivity of Deep Sediments at the Idaho National Laboratory, Idaho. Retrieved October 4, 2009, from U.S. Geological Survey. Website: http://pubs.usgs.gov/sir/2007/5093/pdf/sir20075093.pdf
U.S. Geological Survey. (2001). Steady-State Centrifuge Method. Retrieved October 4, 2009, from USGS Science for a changing world. Website: http://www.rcamnl.wr.usgs.gov/uzf/ssc.html
U.S. Geological Survey. (2001). Unsaturated-Zone Flow Project. Retrieved October 4, 2009, from USGS Science for a changing world. Website: http://www.rcamnl.wr.usgs.gov/uzf/
Organic Matter Content
Washington State University. Tree Fruit Research & Extension Center. (2004). Cation-Exchange Capacity (CEC). Retrieved September 28, 2009 from: http://soils.tfrec.wsu.edu/webnutritiongood/soilprops/04CEC.htm
Environmental Protection Agency (EPA). (1995) Decision Maker’s Guide to Solid Waste Management, Volume 2. EPA 530-R-95-023. Glossary and Chapters accessed October 6, 2009 from http://www.epa.gov/waste/nonhaz/municipal/dmg2/glossary.pdf
Saturated hydraulic conductivity
ETM 523 Lecture Materials Fall 09 by Dr. David Edwards.
Natural Resources Conservation Service (NRCS) United States Department of Agriculture Website. “Saturated Hydraulic Conductivity: Water Movement Concepts and Class History.” Retrieved October 4, 2009 from http://soils.usda.gov/technical/technotes/note6.html
Unsaturated hydraulic conductivity
AGVISE Laboratory. Unsaturated Hydraulic Conductivity. Retrieved October 4, 2009, from AGVISE Laboratory. Website: http://www.agvise.com/tech_art/unsathy.php
Australian Government Connected Water. Hydraulic Conductivity Measurement. Retrieved October 4, 2009, from Australian Government Website: http://www.connectedwater.gov.au/framework/hydrometric_k.php
Daniel, D.E. & Trautwein, S.J. (1994). Hydraulic Conductivity and Waste Contaminant Transport in Soil. Philadelphia, PA.
Perkins, K.S., & Winfield, K.A. (2007). Property-Transfer Modeling to Estimate Unsaturated Hydraulic Conductivity of Deep Sediments at the Idaho National Laboratory, Idaho. Retrieved October 4, 2009, from U.S. Geological Survey. Website: http://pubs.usgs.gov/sir/2007/5093/pdf/sir20075093.pdf
U.S. Geological Survey. (2001). Steady-State Centrifuge Method. Retrieved October 4, 2009, from USGS Science for a changing world. Website: http://www.rcamnl.wr.usgs.gov/uzf/ssc.html
U.S. Geological Survey. (2001). Unsaturated-Zone Flow Project. Retrieved October 4, 2009, from USGS Science for a changing world. Website: http://www.rcamnl.wr.usgs.gov/uzf/
Organic Matter Content
Washington State University. Tree Fruit Research & Extension Center. (2004). Cation-Exchange Capacity (CEC). Retrieved September 28, 2009 from: http://soils.tfrec.wsu.edu/webnutritiongood/soilprops/04CEC.htm
Soil Microbial Activity
Hyman, M. & Dupont, R.R. (2001) Groundwater and Soil Remediation: Process Design and Cost Estimating of Proven Technologies. Reston, VA: American Society of Civil Engineers (ASCE Press).
Hyman, M. & Dupont, R.R. (2001) Groundwater and Soil Remediation: Process Design and Cost Estimating of Proven Technologies. Reston, VA: American Society of Civil Engineers (ASCE Press).
Environmental Site Clean Up
Kandy Van Meeteren
What would a buyer looking at commercial property want to know when purchasing? The knowledge of knowing who owned the property before, hazardous sites are not just for industrial or abandoned buildings anymore. The buyer needs to be aware of what could be on the site that may be detrimental to development of that property.
Understanding the procedures of a Phase I ESA is the buyer responsibility in knowing what is being purchased on that parcel of land. With the current federal laws the owner is responsible for all contaminations on the property even if the owner did not create the problem. The Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) or the Superfund Law makes the owner responsible for clean up if contamination is found. Clean up for a spill or hazard can cost in the millions of dollars and time some business do not have or can afford.
According to Western States Environmental, INC., the cost of a Phase I assessment could cost a small retail parcel from $1,000 to $2,000. An industrial site could cost up to $10,000 or more. This would be used to determine who the liability and the cost associate with the cleanup of the site if there were a hazard found. This report does not guarantee that the property has no hazards or contamination because this is merely an assessment from trained inspectors what they observed on the property.
References
www.spillcleanup.com/Environmental%20Site%20Assessments.htm
Fundamentals of Site Remediation John Pichtel 2nd edition, Government Institutes. 2007. pgs: 105-142.
Kandy Van Meeteren
What would a buyer looking at commercial property want to know when purchasing? The knowledge of knowing who owned the property before, hazardous sites are not just for industrial or abandoned buildings anymore. The buyer needs to be aware of what could be on the site that may be detrimental to development of that property.
Understanding the procedures of a Phase I ESA is the buyer responsibility in knowing what is being purchased on that parcel of land. With the current federal laws the owner is responsible for all contaminations on the property even if the owner did not create the problem. The Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) or the Superfund Law makes the owner responsible for clean up if contamination is found. Clean up for a spill or hazard can cost in the millions of dollars and time some business do not have or can afford.
According to Western States Environmental, INC., the cost of a Phase I assessment could cost a small retail parcel from $1,000 to $2,000. An industrial site could cost up to $10,000 or more. This would be used to determine who the liability and the cost associate with the cleanup of the site if there were a hazard found. This report does not guarantee that the property has no hazards or contamination because this is merely an assessment from trained inspectors what they observed on the property.
References
www.spillcleanup.com/Environmental%20Site%20Assessments.htm
Fundamentals of Site Remediation John Pichtel 2nd edition, Government Institutes. 2007. pgs: 105-142.
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