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Soil Contamination & Remediation

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Presentation on theme: "Soil Contamination & Remediation"— Presentation transcript:

1 Soil Contamination & Remediation
Bioremediation Technology for the Remediation of Persistent Organic Pollutants (POPs): Toxaphene & Dichlorodiphenyltrichloroethane (DDT) Siti Jariani Mohd Jani SWS 6262 : Soil Contamination & Remediation

2 Selected Contaminated Site : Remediation Technology:
Outline Selected Contaminated Site : Woodbury Chemical Company Superfund site, Commerce City, Colorado Contaminants: Toxaphene DDT Remediation Technology: Applied Recommended

3 Contaminated Site History
Pesticide formulation facility 1965 Fire destroyed the main building Soil, debris, bags of water soaked pesticides were dumped 1976 First site sampling by Health Department 1983 Superfund National Priorities List (NPL) 1986 Starts of remediation works in May 1992 Completion of remediation works 1993 Removal from NPL (no further operation activities & maintenance are needed)

4 Population / Residential area
Site Information Site details Woodbury Chemical Company Superfund Site, Commerce City, Colorado Size Total area: 15 hectares Wells: downgradient (West- Northwest) of Woodbury site, between South Platte and the conyaminated site 30 industrial or residential wells 11: Groudwater from bedrock aquifer 19: Surface aquifer (downgradient well, DGW) The nearest DGW 0.5 miles away the South Platte municipal drinking water Water for irrigation Population / Residential area Within 1 mile: 3000 0.3 mile: Mobile home park

5 Site Information (cont.)
Groundwater Unconfined aquifer conditions in the alluvium and semi-confined aquifer conditions in the underlying bedrock Depth: 30 feet. Water table: feet below the ground surface. water flow: to the west and northwest, towards the South Platte River. Surface water Runoff off-site via 3 major drainage channels on the site drain to the north and west. Discharges into a drainage ditch that runs along the northern boundary of the site in a westerly direction for about 3,000 feet before emptying into a retention pond. Evaporation and infiltration lead to water loss from the pond. Major waterways: To the South Platte River EPA Superfund Record of Decision, 1985 (EPA/ROD/R08-85/003)

6 Contaminated Site 2.2 acre of disposed rubble and debris
Contaminated land size 2.2 acre of disposed rubble and debris Disposable site: flat (550 ft long X 175 ft wide) Disposable rubble and debris piles: 4 ft height Major source of contaminants Toxaphene DDT Types of media treated & quantity Rubble & debris piles: 250 cubic yards Soils: 5470 cubic yards Remediation Technology Excavation Incineration Remediation plan To achieve cleanup concentration value of 3 ppm for total pesticides = 5kg of total pesticides remaining in the 2.2 acre site EPA Superfund Record of Decision, 1985 (EPA/ROD/R08-85/003)

7 Contamination at each Medium
Medium/characteristic Descriptions Soil: Pesticide contamination discovered at different depth from soil boring of installed monitor well MW3: toxaphene (12ppm) – Upper 10 feet RSO-8: total pesticide level of ppm (60% is toxaphene) – 10 feet RSO-10: total pesticide level of 4 ppm at feet (toxephene the only contaminants to exceed 1 ppm) Sediments In 1984 & 1985: on and off-site in sample of drainage ditch sediments. Groundwater July 1984: total pollutants concentration of ug/L – in 2 of 5 monitored wells. November 1984: No concentration of pollutants was found. Surface water 1979: DDT, highest concentrations at 25.3 ug/L EPA Superfund Record of Decision, 1985 (EPA/ROD/R08-85/003)

8 Contaminants POPs Toxaphene DDT Chemical Structure Characteristic
Insecticide Persistent in the environment and can be transported in the environment over very long distances. T1/2: 100days -12 years Insecticide: kill weeds and vector-borne diseases like typhus and malaria Persistency leads to bioaccumulate and biomagnification effect on organisms in the environment. T1/2: 2-15 years Toxicity Probable human carcinogen (USEPA possibly carcinogen to humans (USEPA Maximum clean up level (MCL) Drinking water: 0.003mg/L Maximum contaminant level goal: 0 Drinking water: 0.007mg/L Maximum contaminant level goal: 0.007mg/L ASTDR, 2010

9 Applied Technology Excavation Incineration
Removal of 250 cubic yards (cy) to EPA permitted incineration facilities. > 100 ppm total pesticides. Ex-situ incineration at EPA permitted facilities: The excavated materials burned in a furnace designed for burning hazardous materials in a combustion chamber at high temperatures Excavated using backhoes and excavator track hoes. Loaded into trucks. Total of 2500 loaded truck. Sent for incineration The soil was covered with tarps Excavation is complete when test results show that the remaining soil around the hole meets established cleanup levels. Large rocks and debris and excess water was removed. The materials are then placed in the combustion chamber heated to an extremely high temperature for a specified period of time. Excavated area filled with clean soil. After an excavation was filled in, the area was covered with landscaped How long? Start in May 1986 and remediation completed in 1992 Total Cost : $2,471,000 EPA Superfund Record of Decision, 1985 (EPA/ROD/R08-85/003)

10 Advantages Can treat most contaminants and address large volumes of contaminated material Hazardous Waste MGM facilities that is well established and reliable A fast clean up method Disadvantages Potential environmental and health effects: Combustion of POPs Dioxins and furan: human carcinogens and can leads to serious human health problem (USEPA)

11 Applicable Technology
Remediation Technology Description Thermal desorption clean up soil that is contaminated with VOCs and SVOCs at depths shallow enough to reach through excavation. Faster and provide better cleanup than other methods, particularly at sites that have high concentrations of contaminants. Thermal desorption is being used or has been selected for use at over 70 Superfund sites across the country. Thermal chemical degradation : Gas phase Chemical reduction (GPCR) GPCR is a thermal-chemical degradation technology that combines high temperature and hydrogen gas to treat POPs. Based on available information, the technology has treated DDT, HCB, PCBs and dioxin in contaminated soil, sediments, and liquids. Due to the high temperature requirement of this technology, GPCR could potentially treat other POPs. Physical-chemical treatment Physical-chemical treatment includes soil vapor extraction, solidification/stabilization, soil flushing, chemical oxidation, and electrokinetic separation. Bioremediation Using natural microorganism (such as bacteria, Fungi, biopolymers) and plants (phytoremediation) to degrade hazardous organic contaminants or convert hazardous inorganic contaminants to environmentally less toxic or nontoxic compounds of safe levels in soils, subsurface materials, water, sludges, and residues. Phytoremediation Uses plants to clean up contaminated environments. Can clean up many types of contaminants including metals, pesticides, explosives, and oil. However, they work best where contaminant levels are low because high concentrations may limit plant growth and take too long to clean up. Plants also help prevent wind, rain, and groundwater flow from carrying contaminants away from the site to surrounding areas or deeper underground. USEPA

12 Recommended Technology
Anaerobic Bioremediation using Blood Meal Soil Phytoremediation using Aquatic Plants Surface water (Allen et. al., 2002 and EPA, 2007) Iowa State University (Iowa State University)

13 Soil : Anaerobic Bioremediation of Toxaphene using Blood Meal
What is it? Biostimulation of native anaerobic with amendment Developed by US EPA’s Environmental Response Team (ERT) Successfully implemented in several sites Full scale cleanup cost: $130 - $271 per cubic yards (EPA, 2007)

14 Materials & Methods Dosages of Blood Meal & Phosphates
Biological Amendment Blood Meal: dried & powdered animal blood (nutrient) Phosphates: added to the contaminated soil as pH buffer Dosages of Blood Meal & Phosphates 1% by weight of contaminated soil 1% by weight of starch (to establish rapid anaerobic conditions Standard recipe (pH 6.7): Equal proportion of monobasic & dibasic phosphates salts (1:1) Low phosphate/starch recipe: Monobasic:dibasic (1:3)

15 Procedures Soil – amendment mixture Transferred to a lined cell
Mix contaminated soil with water Method: Blending in a dump truck, mechanical mixing in a pit or mixing in pug mill Transferred to a lined cell Add water to produce slurry To maintain anaerobic condition, up to a foot of water is recommended above the settled solid Covered lined cell with a plastic sheet Isolate the cell from the environment Incubated for several month Sampling Procedures

16 Performance Data Sites Site Name Treated soil (cy)
Cell dimensions (ft) Initial contaminants concentration (mg/kg) Final concentration (mg/kg) Period (Days) Percent Reduction (%) Cost (USD) total/ per (cy) Navajo Vats Chapter Laahty Family Dip Vat 253 73:30:4 29 4 31 86 $75,000/ $296 Henry O Dip Vat 23 75:35:5 65:30:5 8 68 67 65,000/ $98 Gila River Indian Community (Cell 1) 875 178:43:7 59 2-4 272 87-98 $793,000/ $226 (Cell 2) (Cell 3) (Cell 4) 211 total 3500 Sources: Allen et al., 2002 and US EPA, 2007. Notes: cy = cubic yard mg/kg = Milligram per kilogram

17 Maintenance Measures Maintenance of water level: Periodic addition of water to treatment cells. Maintenance of treatment cells from leaks Maintaining cover integrity Gas build-up monitoring Odours monitoring Monitoring remedial progress by soil sampling Waste/Residuals Low chlorinated chlorobornane congeners Chloride ions Gaseos waste: CO2, methane, hydrogen sulphide

18 Surface water: Phytoremediation of DDT using aquatic plants
What is it? Phytoremediation is an innovative technology that uses plants to get rid of contaminants from soil, groundwater, air, sediments, and surface. Comprised of several different techniques that utilize vegetation, its related enzymes, and other complex processes. Collectively, these processes are able to isolate, destroy, transport, and remove organic and inorganic pollutants from contaminated media. Study done by Iowa State University (Metalochlor & Atrazine) Reduced in the concentration of contaminants

19 Remediation Plant Ceratophyllum demersum (coontail, hornwort)
Elodea canadensis (American elodea, Canadian pondweed) Lemna minor (common duckweed)

20 Performance Data: Concentration of pollutants remain after 16days
Ceratophyllum demersum Elodea canadensis Lemna minor Metolochlor 1.44 % 4.06% 22.7% Atrazine 41.3% 63.2% 85% Sources: Rice et al., Iowa State University

21 Limitations Anaerobic bioremediation (blood meal)
Temperature. Not to extremely cold climates. Best operation periods: Spring and summer. Bench scale test: to determine applicability at a given site, and to estimate duration of treatment. Minimal duration for treatment: Five weeks Treated low-strength waste contaminated with toxaphene (EPA, 2007) Phytoremediation (Aquatic Plants) Pilot test: select the most effective species of aquatic plant that can remediate the contaminants. (EPA, 2008) Plants that absorb contaminants from the water do not biodegrading them to non-toxic compounds and commute them to their stems or leaves could potentially harm herbivores (Frazar, 2000).

22 Conclusions Incineration: Effective but high risk to human health
Bioremediation & Phytoremediation has been seen as an innovative alternative with great potential that should be explored and developed (Frazar,2000) Despite its limitations; minimal exposure of contaminants to human environmentally safe cheap

23 Thank You Q&A Session

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