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Nature's Response to Land Contamination
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
VOCs are also released directly onto the ground surface through leaks or spills at or near the surface. Sources of these leaks include underground storage tanks, service stations, refineries, and pipelines. Because of these surface and shallow subsurface releases, VOCs are common groundwater contaminants and have been detected in the groundwater of numerous aquifers in the United States (USGS 2006a). A study of groundwater in the United States detected VOCs at a concentration of 0.02 ug/L in more than 50% of approximately 3,500 samples collected from 100 different groundwater aquifers across the country (USGS 2006a). The VOCs detected most often included: bromoform, bromodichloromethane, chloroform, chloromethane, 1,1-dichloroethane, dichlorodifluoromethane, methylene chloride, dibromodichloromethane, MTBE, TCE, PCE, 1,1,1-TCA, trans-1,2-dichloroethene, toluene, and trichlorofluoromethane. This same study indicates the vulnerable nature of many aquifers of the United States, and their location corresponds with many urban areas. In fact, of the 28 major urban areas of the United States, 27 have detectable concentrations of VOCs (only Kansas City is missing) and represent a population of 125.4 million—over 41% of the entire US population. Figure 4.14 shows the locations where VOCs were detected (USGS 2006a).
Chemistry of Contaminants
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
VOCs are also released directly onto the ground surface through leaks or spills at or near the surface. Sources of these leaks include underground storage tanks, service stations, refineries, and pipelines. Because of these surface and shallow subsurface releases, VOCs are common groundwater contaminants and have been detected in the groundwater of numerous aquifers in the United States (USGS 2006a). VOC contaminant degradation rates vary widely and depend on many factors, including: (1) the nature of the release; (2) the physical chemistry of the contaminants themselves; (3) the geological environment where the contaminants are released; and (4) the presence, type, and distribution of microorganisms (Howard et al. 1997; USEPA 1998a, 1998b; McKone and Enoch 2002; USGS 2006a).
The Science of Contamination
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
VOCs are also released directly onto the ground surface through leaks or spills at or near the surface. Sources of these leaks include underground storage tanks, service stations, refineries, and pipelines. Because of these surface and shallow subsurface releases, VOCs are common groundwater contaminants and have been detected in the groundwater of numerous aquifers in the United States (USGS 2006a). A study of groundwater in the United States detected VOCs at a concentration of 0.02 ug/L in more than 50% of approximately 3,500 samples collected from 100 different groundwater aquifers across the country (USGS 2006a). The VOCs detected most often included: bromoform, bromodichloromethane, chloroform, chloromethane, 1,1-dichloroethane, dichlorodifluoromethane, methylene chloride, dibromodichloromethane, MTBE, TCE, PCE, 1,1,1-TCA, trans-1,2-dichloroethene, toluene, and trichlorofluoromethane.
Experimental investigations of soil fluidization by an upward water leak jet
Published in Urban Water Journal, 2023
Sara Ghorbany, Vahid Hamedi, Masoud Ghodsian
Few studies have been conducted to investigate leakage effects on the surrounding soil. Underground pipelines are usually buried in granular materials. When a leak occurs in a pressurized pipe, water (or other liquid) escapes into the surrounding soil, often causing local fluidization of the soil. Recent studies have shown that in the presence of a significant flow rate, leakage in distribution pipes can cause internal fluidization of the soil adjacent to the leak. When inter-particle interactions become insignificant, and the particles are free to move with the pore fluid, fluidization of the granular material occurs.
CFD-based simulation of accidental fuel release from LNG-fuelled ships
Published in Ships and Offshore Structures, 2022
During the initial stage of a leak, the source of the leakage must be identified. LNG mostly comprises a mix of methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), and higher hydrocarbons. Nitrogen is often added as an inert gas component. Table 2 summarises the LNG mixture used in this study, and Table 3 lists its thermo-physical properties.
Review on Liquid-level Measurement and Level Transmitter Using Conventional and Optical Techniques
Published in IETE Technical Review, 2019
Yadvendra Singh, Sanjeev Kumar Raghuwanshi, Soubir Kumar
Another type of sensors commonly used is pressure transducer, which finds application in liquid measurement system too. The basic concept here is that the pressure of fluid increases as depth increases. These sensors are mostly developed using low-temperature coffered ceramic (LTCC). Ceramic MEMS are very practical as they are highly stable even in harsh conditions and high temperatures [5–11]. There are basically two types of pressure sensors that are used in liquid-level measurement-piezo-resistive strain gauge pressure sensor and capacitive pressure sensor. Their design and performance in terms of operation in presence of disturbance like electromagnetic interference, parasitic capacitance has been discussed in Ref. [12]. They have inferred that even though piezoelectric pressure sensor has high power consumption; the implementation is easy, noise and signal conditioning demand is low, compared to capacitive pressure sensor. Also, the environmental impact on sensor is low in the earlier one. LTCC-based pressure sensor in water-level measurement techniques has been studied in depth in Refs. [13,14]. This papers verified that LTCC-based sensors have high durability and are hardly affected by the environmental changes. However, regular calibration is necessary to maintain the accuracy and it is preferred that an additional protective coating is added to the sensor [13]. Another application of pressure sensor is monitoring the water flow in distributed pipeline system [15]. The selection was based on the fact that it was easy to install in pipes and cost-effective. Measurement of pressure has been used for leak detection. To improve accuracy of the sensor calibration, different algorithms are used. Such as SCADA system for real-time data and after appropriate processing, the location of leakage can be found out. The performance of measuring device dips with liquid variation as well as change in pipeline dimension, increasing noise amplitude in the liquid-level measurement system. A solution to tackle this problem has been presented in Ref. [16], based on wavelet transform. The same system can be used for water quality monitoring using algorithms for contamination detection, readings taken using microcontrollers [17].