5) There is a superfund site (a former dumping ground for toxic chemicals) off o
ID: 931854 • Letter: 5
Question
5) There is a superfund site (a former dumping ground for toxic chemicals) off of Douglas road near Grape road in Mishawaka. The report by the EPA is on the following page. Read the description and the Remedy section and answer the following questions: a) What methods would you suggest using to determine what gases are present in the landfill? Suggest a possible method for collecting the gases. Rationalize your decision. b) What method would you suggest for monitoring the groundwater samples? Be specific in your choice of analysis. Rationalize your decision.
Site Name: DOUGLAS ROAD UNIROYAL INC LDFL EPA ID: IND980607881Operable Unit: 01 ROD ID: EPA/ROD/R05-95/288 ROD Date: 07/13/95Contaminant: Methyl ethyl ketone, acetone, tetrahydrofuran, toluene, hexane, and xylene. The Douglas Road Landfill site is located in St. Joseph County just north of Mishawaka, Indiana. The site is approximately 16 acres in size and is located near the northwest corner of Douglas and Grape Roads. The site is bound to the north by the Indiana State Toll Road, to the east by a shopping center and an apartment complex, to the south by residential properties and to the west by agricultural land. In the early 1950s, the property was excavated and gravel on site was used for the construction of the interstate highway. Uniroyal Plastics, Inc. (Uniroyal) leased the gravel pit and used it as a repository for plant wastes between 1954 and 1979. From 1954 to 1971, solvents, fly ash, paper, wood stock, rubber and plastic scrap were disposed of at the landfill. Only fly ash was disposed of from 1971 to 1979. In December 1979, the site was closed to compliance with impending RCRA regulations pertaining to the operation of a landfill. According to the information provided by Uniroyal, approximately 302,400 gallons of RCRA hazardous waste were disposed of at the landfill. Liquid wastes include methyl ethyl ketone, acetone, tetrahydrofuran, toluene, hexane, and xylene. Historical aerial photographs of the landfill indicate several pits containing liquid that may have been used for disposal; the largest (and longest used) was in the central area of the landfill. The landfill was proposed for inclusion on the NPL on March 31, 1989, and placed on the NPL on June 10, 1989. In September 1989, the State of Indiana and Uniroyal signed a consent decree, in which Uniroyal agreed to perform a RI/FS at the site. Before completion of this work, Uniroyal filed for bankruptcy and discontinued work at the site. A RI/FS was performed including activities to determine the nature and extent of contamination at the site and evaluating the feasibility of various remedial alternatives to clean up the site. The RI/FS determined that soil and waste materials and area groundwater had become contaminated because of past disposal activities at the Site. This Record of Decision (ROD) addresses contaminated soil and waste materials. These areas were determined to pose risks to human health and the environment due to dermal contact or incidental ingestion of site surface soils. Remedy: The selected remedial action for this site includes several components. The first component is to install a Composite Barrier Cap with a GCL Soil Barrier Layer. The second component is to collect and dispose of landfill gas. The third component is to dig perimeter ditches to collect surface water drainage. The fourth component is to establish groundwater and source monitoring to ensure that the goals of this action are met.
Explanation / Answer
a) Landfill gas contains many different gases. Methane and carbon dioxide make up 90 to 98% of landfill gas. The remaining 2 to 10% includes nitrogen, oxygen, ammonia, sulfides, hydrogen and various other gases. Landfill gases are produced when bacteria break down organic waste. The amount of these gases depends on the type of waste present in the landfill, the age of the landfill, oxygen content, the amount of moisture, and temperature. For example, gas production will increase if the temperature or moisture content increases. Though production of these gases generally reaches a peak in five to seven years, a landfill can continue to produce gases for more than 50 years.
typical landfill gases, components and characteristics:
Usually LFG(landfill gases) is collected using a system of wells or trenches. These wells or trenches are connected, through piping, to a large industrial fan or other vapor moving unit which maintains a negative pressure on the whole gas collection system. Negative pressure means that the fan is always pulling gases out of the system, never pushing gases into the system. In this way, LFG is vacuumed out of the landfill.
Landfill gas can be collected by either a passive or an active collection system. :
Passive Gas Collection Systems : The collection wells are typically constructed of perforated or slotted plastic and are installed vertically throughout the landfill to depths ranging from 50% to 90% of the waste thickness.
If groundwater is encountered within the waste, wells end at the groundwater table. Vertical wells are typically installed after the landfill, or a portion of a landfill, has been closed. A passive collection system may also include horizontal wells located below the ground surface to serve as conduits for gas movement within the landfill.
Active Gas Collection : Well-designed active collection systems are considered the most effective means of landfill gas collection. Active gas collection systems include vertical and horizontal gas collection wells similar to passive collection systems. Unlike the gas collection wells in a passive system, however, wells in the active system should have valves to regulate gas flow and to serve as a sampling port. Sampling allows the system operator to measure gas generation, composition, and pressure.
b) ground water samples monitoring generally refers to collection of all samples of contaminants present in ground water. For this purpose one general method is used which is small diameter groundwater monitoring(sampling) wells are installed by direct push. Sampling wells can be installed by using a bailer or by using a pump.
sampling wells using a bailer : Bailers are only acceptable for purging and sampling wells where the static water level in the well is 30 feet or less from grade, or in extremely slow recharging wells.
sampling wells using a pump : Pumps can be used to sample any well with sufficient recovery. If recovery is so slow that a satisfactory water column height (for normal pump operation) is not reached in a reasonable amount of time, a bailer can be used for sample collection.
component percentage by volume characteristics Methane 45-60 Methane is a naturally occurring gas. It is colorless and odorless. Landfills are the single largest source of U.S. man-made methane emissions Carbon dioxide 40-60 Carbon dioxide is naturally found at small concentrations in the atmosphere (0.03%). It is colorless, odorless, and slightly acidic nitrogen 2-5 Nitrogen comprises approximately 79% of the atmosphere. It is odorless, tasteless, and colorless oxygen 0.1-1 Oxygen comprises approximately 21% of the atmosphere. It is odorless, tasteless, and colorlessRelated Questions
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