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Oakland, CA, United States

Prashar Y.,East Bay Municipal Utility District | McMullin R.,East Bay Municipal Utility District | Irias X.,East Bay Municipal Utility District | Flores M.,HDR | Khatri K.,Langan Inc.
Pipelines 2014: From Underground to the Forefront of Innovation and Sustainability - Proceedings of the Pipelines 2014 Conference | Year: 2014

The East Bay Municipal Utility District (EBMUD) is major water utility providing water to more than 1.3 million people on the eastern side of the San Francisco Bay Area. The EBMUD has approximately 4,200 mi of treated water distribution and transmission pipelines within a 331 sq mi customer service area. Approximately 360 mi of this system are large-diameter pipelines consisting of 20 in. and larger welded steel pipe, 36-in. and larger reinforced concrete cylinder pipe, 16-in. and larger diameter cast-iron pipe, and 20-in and larger pretensioned concrete cylinder pipe. System data are managed using a comprehensive geographic information system (GIS) geodatabase of pipeline characteristics, location, and seismic hazard. Due to the proximity to active faults such as the Hayward Fault, Calaveras Fault, San Andreas Fault, and Concord Fault, the EBMUD service area is very susceptible to earthquakes. Previous studies have suggested that water pipelines are damaged during earthquakes when settlements impose high stresses on the pipeline and its components. Permanent ground deformation is estimated from seismic hazards such as a landslide, fault offset, or liquefaction-induced settlements. A service area that represents this scenario is the City of Alameda, where soil is highly liquefiable in the event of an earthquake. The geology of the city is compromised predominantly by artificial fill and Holocene alluvial fan deposits, with the artificial fill being the most vulnerable to liquefaction. Using 212 cone penetration tests (CPT) soundings located throughout the City of Alameda and geographic information systems (GIS), a pipeline fragility study is performed to determine pipeline segments that have the potential for failure or some level of damage during an earthquake event. In addition, a pipeline map similar to the United States Geologic Survey (USGS) ShakeMap will be created to identify damaged pipeline segments and their corresponding level of damage. After identifying pipeline segments with potential for failure, a repair program is outlined by the authors. The researchers generate the prediction model for the pipeline fragility study for the EBMUD service area, the City of Alameda, based on settlement values obtained by peak ground acceleration values (PGA) and a M7.0 earthquake magnitude. Estimated liquefaction-induced settlement values are verified using the program software SHAKE2000. © 2014 American Society of Civil Engineers. Source


Geng X.,New Jersey Institute of Technology | Boufadel M.C.,New Jersey Institute of Technology | Lee K.,Commonwealth Scientific and Industrial Research Organization | Abrams S.,Langan Inc. | Suidan M.,University of Cincinnati
Water Resources Research | Year: 2015

The aerobic biodegradation of oil in tidally influenced beaches was investigated numerically in this work using realistic beach and tide conditions. A numerical model BIOMARUN, coupling a multiple-Monod kinetic model BIOB to a density-dependent variably saturated groundwater flow model 2-D MARUN, was used to simulate the biodegradation of low-solubility hydrocarbon and transport processes of associated solute species (i.e., oxygen and nitrogen) in a tidally influenced beach environment. It was found that different limiting factors affect different portions of the beach. In the upper intertidal zone, where the inland incoming nutrient concentration was large (1.2 mg N/L), oil biodegradation occurred deeper in the beach (i.e., 0.3 m below the surface). In the midintertidal zone, a reversal was noted where the biodegradation was fast at shallow locations (i.e., 0.1 m below the surface), and it was due to the decrease of oxygen with depth due to consumption, which made oxygen the limiting factor for biodegradation. Oxygen concentration in the midintertidal zone exhibited two peaks as a function of time. One peak was associated with the high tide, when dissolved oxygen laden seawater filled the beach and a second oxygen peak was observed during low tides, and it was due to pore oxygen replenishment from the atmosphere. The effect of the capillary fringe (CF) height was investigated, and it was found that there is an optimal CF for the maximum biodegradation of oil in the beach. Too large a CF (i.e., very fine material) would attenuate oxygen replenishment (either from seawater or the atmosphere), while too small a CF (i.e., very coarse material) would reduce the interaction between microorganisms and oil in the upper intertidal zone due to rapid reduction in the soil moisture at low tide. © 2015. American Geophysical Union. All Rights Reserved. Source


Geng X.,New Jersey Institute of Technology | Boufadel M.C.,New Jersey Institute of Technology | Lee K.,Oceans and Atmosphere Flagship | Abrams S.,Langan Inc. | Suidan M.,University of Applied and Environmental Sciences
Water Resources Research | Year: 2015

The aerobic biodegradation of oil in tidally influenced beaches was investigated numerically in this work using realistic beach and tide conditions. A numerical model BIOMARUN, coupling a multiple-Monod kinetic model BIOB to a density-dependent variably saturated groundwater flow model 2-D MARUN, was used to simulate the biodegradation of low-solubility hydrocarbon and transport processes of associated solute species (i.e., oxygen and nitrogen) in a tidally influenced beach environment. It was found that different limiting factors affect different portions of the beach. In the upper intertidal zone, where the inland incoming nutrient concentration was large (1.2 mg N/L), oil biodegradation occurred deeper in the beach (i.e., 0.3 m below the surface). In the midintertidal zone, a reversal was noted where the biodegradation was fast at shallow locations (i.e., 0.1 m below the surface), and it was due to the decrease of oxygen with depth due to consumption, which made oxygen the limiting factor for biodegradation. Oxygen concentration in the midintertidal zone exhibited two peaks as a function of time. One peak was associated with the high tide, when dissolved oxygen laden seawater filled the beach and a second oxygen peak was observed during low tides, and it was due to pore oxygen replenishment from the atmosphere. The effect of the capillary fringe (CF) height was investigated, and it was found that there is an optimal CF for the maximum biodegradation of oil in the beach. Too large a CF (i.e., very fine material) would attenuate oxygen replenishment (either from seawater or the atmosphere), while too small a CF (i.e., very coarse material) would reduce the interaction between microorganisms and oil in the upper intertidal zone due to rapid reduction in the soil moisture at low tide. © 2015. American Geophysical Union. All Rights Reserved. Source


Bedison J.E.,University of Pennsylvania | Bedison J.E.,Langan Inc. | Scatena F.N.,University of Pennsylvania | Mead J.V.,Drexel University
Forest Ecology and Management | Year: 2013

This study investigated the landscape characteristics that influence C and N in unsaturated surface soils of riparian zones along 1st to 3rd order streams in the Atlantic Coastal Plain of the Delaware River Basin. Unsaturated surface soils (0-30cm) were sampled in forested and non-forested sites at 29 locations throughout S New Jersey and SE Pennsylvania. Overall, the soil %C and %N in forested and non-forested riparian sites studied in this investigation were comparable to similar riparian zone soils in eastern North America. However, the soil C and N contents of these Atlantic Coastal Plain soils were 3 to 8-fold greater which underscores the value of these riparian soils as C pools. Soil C content (100.3±15.0Mgha-1) in forested riparian sites was consistently higher but not statistically different (P>0.05) from soil C content (90.6±12.1Mgha-1) in non-forested riparian sites. Likewise, neither soil N storage or the C:N ratio were different between the contrasting land covers but forested sites with forest floor organic horizons had significantly greater (82%, P=0.004) soil C storage than the non-forested sites. Of the forested sites, 70% did not have organic horizons. All of the forested sites without organic horizons had abundant earthworms and comparisons of sites with and without forest floor suggests that earthworms and the removal of native forest cover may be responsible for a loss of 75-93Mgha-1 of soil C from these riparian zones. Multivariate regression tree analysis was able to explain ≥50% of the variability in soil C and N and as much as 68% of the variability in the C:N ratio. The analysis indicated that watershed-scale land cover, local soil series, and elevation above the active channel had the greatest influence on C and N storage. Moreover, this analysis indicated that a combination of easily measured, reach-scale characteristics and GIS-based watershed-scale variables can be used to estimate regional riparian soil C pools and identify restoration sites with the potential to store soil C. © 2013 Elsevier B.V. Source


Lee A.,Langan Inc. | Abrams S.H.,Langan Inc. | Moskal E.,ARS Technologies Inc | Ciambruschini S.,Langan Inc. | Moss D.,Brixmor Property Group
Remediation | Year: 2013

This article presents a case study of the source-area treatment of tetrachloroethene (PCE) in a low-permeability formation using zero-valent iron (ZVI). Evidence of the stimulation of biological reduction processes within the treatment zone occurred. Pneumatic fracturing and injection of microscale ZVI slurry in the overburden and weathered bedrock zones was performed at a commercial brownfields redevelopment site in Maryland. A 20,000-square-foot source area impacted with PCE at concentrations greater than 15,000 μg/L was treated at depths ranging from 10 to 70 feet bgs. An average ZVI dosage of 0.0024 iron-to-soil mass ratio within the overburden zone led to a 75 percent decrease in PCE mass in less than one year. For the weathered bedrock zone, an average 0.0045 iron-to-soil mass ratio resulted in a 92 percent decrease in PCE mass during the same period. The reducing environment and hydrogen generated by the ZVI may have stimulated Dehalobacter populations, as evidenced by concentrations up to 104 cells per milliliter measured within the treatment area despite a groundwater pH as high as 9. The biological reductive dechlorination of the chlorinated ethenes explains the temporary increase in trichloroethene and cis-1,2-dichloroethene concentrations. © 2013 Wiley Periodicals, Inc. Source

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