FREE ELECTRONIC LIBRARY - Dissertations, online materials

Pages:     | 1 || 3 |

«Signature: _ April 13, 2012 Vijay Selvan Ram A Deterministic and Probabilistic Analyses of the Carbon Tetrachloride Contaminant Plume in Groundwater ...»

-- [ Page 2 ] --

33 organic compounds, of which 64% were reliably identified, were found at the former UCIL formulation plant. Among the compounds identified were four isomers (alpha-, beta-, delta- and gamma-) of hexachlorocyclohexane (HCH), which were all

–  –  –

products in the production process at UCIL. 400 meters north of the main UCIL site are the Solar Evaporation Ponds (SEPs), which collect waste after they have been neutralized and treated, and with the exception of mercury, the concentrations of other heavy metals were below background. An organic analysis found 15 compounds of which approximately 20% were identified; yet only a few organic compounds were identified reliably when compared with other sites (Labunska et al. 1999).

They collected groundwater samples from twelve drinking water wells both to the north and south of the UCIL site (Figure 3) and detected high levels of chloroform, carbon tetrachloride and chlorinated benzenes in wells close to the northern boundary of the plant (Labunska et al. 1999). A later study carried out in 2004 also found similarly high levels from a drinking water hand-pump located near the southern boundary of the plant (Labunska et al. 2004).

Pollution Monitoring Laboratory (PML) In 2009, scientists from the Pollution and Monitoring Laboratory (PML), in association with the Centre for Science and Environment (CSE) collected soil and water samples from inside and outside the UCIL factory. These samples included water samples collected from handpumps, borewells and dugwells from residential areas around the UCIL plant, and from as far as 3.5 km away. Waste samples from waste storage sheds, soil samples from within the factory premises, the SEPs, and surface water samples show contamination of HCH isomers and heavy metals. They found results similar to Greenpeace, with groundwater samples being heavily contaminated with chlorinated benzene compounds and organochlorine pesticides (Johnson et al., 2009).

–  –  –

NEERI, an institute devoted to the intersection of environmental concerns and human public health, performed three rounds of sampling and geophysical investigations on UCIL premises to determine the extent of contamination in both soil and groundwater.

Soil sampling within UCIL premises, outside the UCIL premises, and groundwater sampling within and outside UCIL premises reveal a contamination profile that is less alarming than the two previously described studies. The geophysical investigations reveal the possibility of chemical contamination at three sites (Site I, Site III and Site V) (Figure 4). From the analysis of groundwater sampled from borewells within the UCIL premises and outside, pesticide contamination was found in 5 wells in the vicinity of UCIL premises along a Northeast axis (NEERI 2010).

Study Objectives This study will attempt to characterize the contaminant plume for CCl 4 in groundwater and create future projections for the contaminant plume at sites along the axis of the direction of groundwater flow. More specifically, the aims for the study will be to 1) characterize the hydrogeology of the site as reported in the literature 2) estimate the source concentrations of CCl 4 3) run a deterministic model using single-point estimates to project the contaminant plume out in space and time, and 4) run a probabilistic model to project a range of likelihoods that the concentration of CCl 4 will exceed drinking water standards set by the World Health Organization (WHO) and the United States Environmental Protection Agency (US EPA).

As Labunska et al. report in their 1999 Greenpeace report, the groundwater under the site flows in the northeast direction. There is an abundance of human settlements

–  –  –

groundwater for those populations that draw their drinking water from this source. The studies outlined above indicate a lengthy profile of contamination of both the soil and groundwater, which includes a number of pesticides and their production intermediates.

However, for the purposes of this study, CCl 4 will help to elucidate some measure of exposure-risk for those residents who drink from this groundwater.

CCl 4, a volatile organic compound (VOC) was chosen because of its reported distribution in the groundwater along the northeast axis. According to Labunska et al., CCl 4 is found in high concentrations in wells along the northern plant boundary, while those concentrations in wells along the southeast corner of the site are lower, though still significantly elevated (Labunska et al. 1999). In addition, the toxicological profile of carbon tetrachloride is well characterized, providing a good justification for assessing their risk.

In order to evaluate the behavior of CCl 4 and its’ associated levels in the groundwater, the software Analytical Contaminant Transport System (ACTS) will be used to study the steady state and time dependent behavior of CCl 4. The ACTS software utilizes environmental models commonly found in the literature for analytical purposes.

It can be used as a screening-level tool for environmental managers and policy-makers to obtain some general knowledge of the system and its behavior. In order to utilize ACTS, hydrogeologic parameters and contaminant properties must be measured, in addition to characterizing the aquifer and contaminant plume. Because this study relies on values from the literature regarding Bhopal and the UCIL site, where uncertainty exists or

–  –  –

methods, producing a range of possible outputs (e.g. a range of contaminant levels at a specified distance after a specified period of time) (Anderson et al., 2010).

Chemical and Contaminant Properties of Carbon Tetrachloride Chronic exposure to CCl 4 can have an adverse effect on liver functioning.

Breakdown products have been shown to attack cell proteins, and in severe cases liver cells can be destroyed leading to a decrease in liver function. If exposure is short-term, these effects can be reversed. Kidneys are also sensitive to CCl 4. It can cause a buildup of water and waste products in the body with potentially fatal consequences if the exposure is too high. There are also neurological symptoms associated with high exposure to CCl 4.

In the most severe cases, coma and permanent damage to nerve cells can result. Animal studies by the Department of Health and Human Services (DHHS) have shown CCl 4 to be possibly carcinogenic. IARC classifies CCl 4 in Group 2B (possibly carcinogenic to humans), while the EPA classifies CCl 4 as a probable human carcinogen (ATSDR 2005).

The World Health Organization (WHO) has set maximum contaminant level guidelines for drinking water for a range of chemical contaminants. The guideline for carbon tetrachloride is 0.004mg/L (WHO 2011). The EPA has set 0.005 mg/L for carbon tetrachloride as the maximum contaminant level (EPA 2011).

–  –  –

Modeling Approach and Assumptions The aquifer under the UCIL pesticide manufacturing facility and the surrounding area was characterized within ACTS as a confined, two-dimensional, saturated, infinite model with constant dispersion coefficients. In order to define the modeling domain, the

–  –  –

Southwest to Northeast, with a maximum length of 2 kilometers, and the y-axis centered on the UCIL facility, extended to include the whole facility with a width of roughly 500

meters. The following assumptions were made for modeling purposes:

1. The contaminant plume will be characterized as flowing in the reported direction of groundwater flow (Labunska 1999, NEERI 2010), with the location of the source remaining constant. Groundwater flow is assumed to be steady and uniform.

2. The surficial aquifer is characterized as infinite, meaning the boundaries of the aquifer are assumed to be far enough away that they do not affect the dispersion coefficient.

3. Because of the limited amount of data regarding soil and groundwater properties specific to the site, certain hydrogeologic parameters (porosity, bulk density of soil, etc) were estimated based on their typical values as reported in the literature.

4. It is assumed that the concentration of CCl 4 is constant and no source remediation has been performed. This is due to the high level concentrations of the contaminants found at the site approximately 15 years after the closing of the site (Labunska et al. 1999) Model Input Parameters and Source Definition for Deterministic Simulations Parameters pertaining to groundwater flow and contaminant characteristics are obtained from a variety of sources including relevant literature articles, existing site field data and measurements taken remotely through Google Earth (Table 1). All of the values for the deterministic analysis are shown in Table 2. The model was calibrated by manual adjustment of input parameters, which most closely approximated the measured concentrations found in field measurements generally located along the axis of

–  –  –

In order to estimate the source concentration of CCl 4, the model was calibrated by varying the concentration at the inflow boundary, assuming the source originated in 1984.

By varying the concentration at the inflow boundary, and adjusting the field and chemical constants, it was determined that 4,000mg/L most closely approximated the concentration measured at the monitoring well used for calibration (Labunska et al. 1999). 4,000mg/L is approximately 5% of the solubility limit of CCl4.

Following calibration, a deterministic scenario was simulated using a constant source scenario under the assumption that there has been no source removal or remediation of the site.

Model Input Parameters for Probabilistic Simulations In order to conduct probabilistic analyses of contaminant transport, two-stage Monte Carlo simulation was performed by generating probability density functions (PDFs) for three input parameters. In the first stage, PDFs were generated for each parameter that had a degree of uncertainty, in other words, the values were recorded in the literature or cited in field measurements as ranges. 10,000 realizations were simulated to characterize the variability in the parameters. In the second stage, another 10,000 realizations of the model were run within ACTS using the inputs of the PDFs for each parameter, thereby creating a range of probabilities of contaminant concentrations in the groundwater for specified times and distances.

The two parameters chosen for two-stage Monte Carlo simulations are the Darcy groundwater velocity and the retardation coefficient. The Darcy groundwater velocity underwent Monte Carlo simulations by varying proxy parameters that are required to

–  –  –

parameters and their distributions are presented in Table 3. Probabilistic simulations will be run for three points of interest, 500m, 1000m and 2000m northeast of the center of the UCIL site for three different time periods. These areas represent dense population centers.

–  –  –

Calibration Results In order to determine the parameters that best estimates measured concentrations of carbon tetrachloride, the model was calibrated by varying the input parameters that achieved results that most closely matched concentrations found in a well roughly 300 meters northeast of the center of the production facility. The concentration at the inflow boundary that most closely matched the concentration measured at IT9030 and IT9032 was 4,000mg/L (Table 4, Figure 3).

Deterministic Model Simulations After having calibrated a set of parameters to appropriately model the system, simulations were conducted using single-value and distributed-value inputs to model the contaminant plume at a maximum distance of 2000 m with different time end-points.

Given the initial source concentration, the deterministic model output shows a normalized concentration of 3.80 x 10-22, which is 1.52 x 10-15mg/L at a location 2000 meters from the source concentration in 2084. To put the results in context, the outcome of interest was the location of the plume, which approached the U.S. EPA MCL, which is represented in the figure as a normalized concentration of 1.25 x 10-6 (Figure 5a-c).

The model was run to simulate the plume at 10, 30 and 50 years since the closing

–  –  –

of the level that represents the EPA level MCL is at a distance of approximately 850 meters from the source. Given a constant source scenario, after 10, 30 and 50 years, distances beyond roughly 850m are not projected to contain concentrations of CCl 4 above 0.005mg/L.

Probabilistic Model Simulations The results for the probabilistic scenario include two histograms showing the probabilistic distributions for the two input parameters that underwent Monte Carlo simulations. Descriptive statistics of each of those input parameters are presented in Table 3 and Figures 6a – 6b.

Three different locations (500m, 1000m and 2000m) were chosen because of their central location in densely populated areas to the northeast of the site. The results of probabilistic simulations for each location show the likelihood of exceeding certain concentrations, particularly the WHO MCL of 0.004mg/L (C/C 0 = 1x10-6) at specified points in space and time. For all simulations (500m, 1000m and 2000m), there is a 100% probability that the concentration of CCl4 exceeds the WHO MCL. For concentrations higher than this, the probabilities drop (Figures 6 – 9).

–  –  –

Contaminant Plume The EPA and WHO have both set drinking water standards for CCl 4, 0.005mg/L and 0.004mg/L, respectively. The model simulations were run in order to determine at what locations and times this concentration is exceeded, and as a result, pose a health risk for the populations exposed to the groundwater. Deterministic simulations show that

–  –  –

be exposed to concentrations of 0.005mg/L. Deterministic simulations show reduced concentrations for populations living further out than 850 meters.

In the probabilistic model simulations, for all distances and times simulated, there is a 100% probability that the concentration of CCl 4 will exceed the WHO MCL of

Pages:     | 1 || 3 |

Similar works:

«when co-administered with other serotonergic agents (including triptans, HIGHLIGHTS OF PRESCRIBING INFORMATION tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, These highlights do not include all the information needed to use Savella buspirone and St. John’s Wort). If such symptoms occur, discontinue safely and effectively. See full prescribing information for Savella. Savella and initiate supportive treatment. If concomitant use of Savella with other serotonergic drugs is...»

«SUBURBAN REVISIONS A Thesis Presented to The Academic Faculty By Alyssa Shank Durden In Partial Fulfillment Of the Requirements for the Degree Master of Architecture I Georgia Institute of Technology August, 2005 SUBURBAN REVISIONS Approved by: Richard Dagenhart, Advisor College of Architecture Michael Dobbins College of Architecture Michael Gamble College of Architecture Date Approved: May 16, 2005 ii to my grandmother, Mary Ellen Shank, who inspired me to write and encouraged me to draw since...»

«Online Password Manager for Workgroups Getting Started Guide Passpack Administration Introduction Browser Requirements Things to Have On-Hand Payments & Billing Getting Acquainted Shared Users, Groups & Permissions Your Password List The Entry Window Creating Your Company Account Setting Up Shared Users Getting Your Team Connected Creating Groups Import Your Passwords Sharing Passwords One By One Bulk Sharing More Popular Features Auto-Login to Websites with Passpack It! Letting Staff Save...»

«Cloud Computing Frameworks for Food Recognition from Images by Sri Vijay Bharat Peddi Thesis submitted to the Faculty of Graduate and Postdoctoral Studies In partial fulfillment of the requirements For the degree of Masters of Applied Science in Electrical and Computer Engineering Ottawa-Carleton Institute for Electrical and Computer Engineering School of Electrical Engineering and Computer Science University of Ottawa © Sri Vijay Bharat Peddi, Ottawa, Canada, 2015 Abstract Distributed cloud...»

«Medications List ANTIARRHYTHMICS Amiodarone: Amiodarone is used for treatment of atrial fibrillation, Ventricular tachycardia and other arrhythmias. It is mainly used as Rhythm control therapy and tries to change abnormal heart rhythm to normal sinus rhythm and maintains it. This medication must be taken with meals as it is better absorbed with food. It is important to have regular checkups, blood tests including thyroid function tests and liver function tests, chest X-Rays and eye exams before...»

«Verification Technology Transfer R. P. Kurshan Cadence Design Systems, Inc., New Providence, NJ 07974 Abstract. In the last quarter century computer-aided verification – especially in the form of model checking – has evolved from a research concept to a commercial product. While the pace of this technology transfer was anything but rapid, the new technology had almost insuperable hurdles to jump on its way to the market place. Hurdle number one was a required significant change in...»

«Suburbs for Sale: Buying and Selling the Great Australian Dream Fiona Allon Centre for Cultural Research, University of Western Sydney Introduction In January 2005, a so-called ‘cultural terrorist’ group from western Sydney released a manifesto announcing its plan to wreak havoc and revenge on the building of oversized homes on standard blocks of land. The houses they planned to target are of course those that have been dubbed ‘McMansions’: large, two or sometimes even three storey...»

«HIGHLIGHTS OF PRESCRIBING INFORMATION Wean patients slowly from systemic corticosteroids if transferring These highlights do not include all the information needed to use to ASMANEX HFA. (5.4) ASMANEX HFA safely and effectively. See full prescribing  Hypercorticism and adrenal suppression: May occur with very high information for ASMANEX HFA. dosages or at the regular dosage in susceptible individuals. If such changes occur, discontinue ASMANEX HFA slowly. (5.5) ASMANEX® HFA (mometasone...»

«Brno Studies in English Volume 38, No. 2, 2012 ISSN 0524-6881 DOI: 10.5817/BSE2012-2-10 Reviews Carol Berkenkotter, Vijay K. Bhatia and Maurizio Gotti (eds.): Insights into Academic Genres. Bern: Peter Lang, 2012. ISBN 978-3-0343-1211-0, 468 pp. Over the eleven years since its establishment in 2001, the series “Linguistic Insights” has won very positive recognition among scholars in various disciplines of linguistics. The series, issued by the publishing house Peter Lang and under the...»

«Paediatric Ocular Disease Simon Barnard Paediatric ocular disease Notes to accompany lecture to 2nd Year City University undergraduates Dr Simon Barnard PhD BSc FCOptom FAAO DCLP Table of Contents Trauma The red eye Eyelids Proptosis Leukocoria EOM anomalies Nystagmus Congenital abnormalities and syndromes Systemic disease and the eye Neurological disease Paediatric neurodevelopmental disorders Further reading Multiple Choice Questions MCQ Answers. do not view till you have attempted all...»

«OXYCHEM C AUSTIC S ODA H ANDBOOK Occidental Chemical Corporation (OxyChem) is a leading North American manufacturer of polyvinyl chloride (PVC) resins, chlorine and caustic soda, key building blocks for a variety of indispensable products such as plastics, pharmaceuticals and water treatment chemicals. Other OxyChem products include caustic potash, chlorinated organics, sodium silicates, chlorinated isocyanurates and calcium chloride. For every product it makes, OxyChem’s market position is...»

«Media Kit Photo: Matt Clarke 1 Table of Contents Photo: Matt Clarke Message from Premier Christy Clark 1 Welcome from Andrew Jakubeit, Mayor of the City of Penticton 2 British Columbia Fact Sheet 3 Overview of Penticton 5 Okanagan Wine Country 7 Media Tours 9 Tour Partners 13 Monday Evening Reception Partners 28 Tuesday Evening Reception Partners 30 Our Sponsors 32 A Message from Premier Christy Clark As Premier of the Province of British Columbia, I am pleased to welcome everyone to Penticton...»

<<  HOME   |    CONTACTS
2016 www.dissertation.xlibx.info - Dissertations, online materials

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.