Maki I.P.,GEI Consultants |
Boulanger R.W.,University of California at Davis |
DeJong J.T.,University of California at Davis |
Jaeger R.A.,GEI Consultants
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2014
Interpretation of experimental and field cone penetration test (CPT) data from across a broad range of stress conditions requires defining the dependence of the measurements on overburden stress and other influencing factors. This paper examines three possible methods for overburden normalization of CPT tip resistance in sand at the same state parameter or same relative state parameter. The three methods for determining state-based normalized tip resistance at a reference overburden stress of 101.3 kPa (1 atm) are evaluated against calibration chamber test data for four well-studied clean sands. The CPT data from the calibration chamber tests are corrected for chamber boundary effects using two different methods to illustrate the effect this step has on derived relationships. The CPTdata are further normalized to a common lateral earth pressure coefficient to illustrate the effect of this step. The three methods for state-based overburden normalization were evaluated for bias and dispersion against the calibration chamber data, including their dependence on the applied chamber correction relationship. The dependence of state-based overburden normalized tip resistances on the crushing behavior of the clean sand was evaluated by examination of onedimensional limiting compression curves for these four sands. Finally, correlations for estimating the state parameter or relative state parameter from the state-based overburden normalized tip resistance were developed and evaluated based on the examined data. © 2013 American Society of Civil Engineers.
DeJong J.T.,University of California at Davis |
Jaeger R.A.,GEI Consultants |
Boulanger R.W.,University of California at Davis |
Randolph M.F.,University of Western Australia |
Geotechnical and Geophysical Site Characterization 4 - Proceedings of the 4th International Conference on Site Characterization 4, ISC-4 | Year: 2013
The characterization of sedimentary soil, and specifically 'intermediate' soils such as silty sands, non-plastic silts, clayey silts, and fine grained tailings are often challenging due to difficulties in sampling and testing and in interpretation of in-situ data. Cone penetrometer testing where the penetration rate is varied to control drainage conditions has been explored recently. The penetration rates required for undrained and drained conditions are proportional to the coefficient of consolidation, and a two order of magnitude change in penetration rate is generally required to move from one limiting condition to another. This paper utilizes experimental, analytical, and numerical research to examine practical implementation issues as well as theoretical details for proper analysis of variable penetration rate test data. Specifically, normalized relationships are presented to relate cone tip and pore pressure measurements to penetration rate. It is shown that partial consolidation during cone penetration at the standard rate of 2 cm/s exists if the t 50 from pore pressure dissipation test is less than 100 seconds. The errors induced by partial consolidation during penetration on interpretation of both soil behavior type charts and pore pressure dissipation data are then examined; a new solution for estimation of the coefficient of consolidation from pore pressure dissipation is presented. A new two-stage automated hydraulic control system capable of penetration rates from 20 cm/s down to 0.002 cm/s is then presented. A practical framework and chart for selection of penetration rates required to obtain drained or undrained measurements for a given soil is discussed. Finally, numerical cavity expansion results using a modified MIT-S1 constitutive model within FLAC indicate that the initial state, in-situ stress, limiting compression curve reference stress, and stress-dilatancy characteristics are the primary factors affecting the ratio of drained to undrained cone tip resistance.
PubMed | Windward, GEI Consultants and EcoTox
Type: Journal Article | Journal: Integrated environmental assessment and management | Year: 2016
We evaluated the use of biokinetic models to predict selenium (Se) bioaccumulation into model food chains after short-term pulses of selenate or selenite into water. Both periphyton- and phytoplankton-based food chains were modeled, with Se trophically transferred to invertebrates and then to fish. Whole-body fish Se concentrations were predicted based on 1) the background waterborne Se concentration, 2) the magnitude of the Se pulse, and 3) the duration of the Se pulse. The models were used to evaluate whether the US Environmental Protection Agencys (USEPAs) existing acute Se criteria and their recently proposed intermittent Se criteria would be protective of a whole-body fish Se tissue-based criterion of 8.1 g g(-1) dry wt. Based on a background waterborne Se concentration of 1 g L(-1) and pulse durations of 1 d and 4 d, the Se pulse concentrations predicted to result in a whole-body fish Se concentration of 8.1 g g(-1) dry wt in the most conservative model food chains were 144 and 35gL(-1), respectively, for selenate and 57 and 16gL(-1), respectively, for selenite. These concentrations fall within the range of various acute Se criteria recommended by the USEPA based on direct waterborne toxicity, suggesting that these criteria may not always be protective against bioaccumulation-based toxicity that could occur after short-term pulses. Regarding the USEPAs draft intermittent Se criteria, the biokinetic modeling indicates that they may be overly protective for selenate pulses but potentially underprotective for selenite pulses. Predictions of whole-body fish Se concentrations were highly dependent on whether the food chain was periphyton- or phytoplankton-based, because the latter had much greater Se uptake rate constants. Overall, biokinetic modeling provides an approach for developing acute Se criteria that are protective against bioaccumulation-based toxicity after trophic transfer, and it is also a useful tool for evaluating averaging periods for chronic Se criteria.
DeForest D.K.,Windward |
Gensemer R.W.,GEI Consultants |
Van Genderen E.J.,ZINC Inc |
Gorsuch J.W.,Copper Development Association Inc
Integrated Environmental Assessment and Management | Year: 2011
Copper (Cu) can impair olfaction in juvenile Pacific salmon (as well as other fishes), thus potentially inhibiting the ability of juveniles to avoid predators or to find food. Because Cu is commonly elevated in stormwater runoff in urban environments, storm events may result in elevated Cu concentrations in salmon-bearing streams. Accordingly, there is concern that existing Cu criteria, which were not derived using data for olfactory-related endpoints, maynot be adequately protective of juvenile salmon. However, a modification of the US Environmental Protection Agency (USEPA) biotic ligand model (BLM) for deriving site-specific Cu criteria was recently proposed, which accounted for the sensitivity of olfactory endpoints. The modification was based on olfactory inhibition in juvenile coho salmon (Oncorhynchus kisutch) exposed to Cu in various combinations of pH, hardness, alkalinity, and dissolved organic carbon (DOC) concentrations. We used that olfactory-based BLM to derive 20% inhibition concentrations (IC20) values for Cu for 133 stream locations in the western United States. The olfactory BLM-based IC20 values were compared to the existing hardness-based Cu criteria and the USEPA's BLM-based Cu criteria for these representative natural waters of the western United States. Of the 133 sampling locations, mean hardness-dependent acute and chronic Cu criteria were below the mean olfactory-based BLM IC20 value in 122 (92%) and 129 (97%) of the waters, respectively (i.e.,<20% olfactory impairment would have been predicted at the mean hardness-based Cu criteria concentrations).Waters characterized by a combination of high hardness and very low DOC were most likely to have hardness-based Cu criteria that were higher than the olfactory-based BLM IC20 values, because DOC strongly influences Cu bioavailability in the BLM. In all waters, the USEPA's current BLM-based criteria were below the mean olfactory-based BLM IC20 values, indicating that the USEPA's BLM-based criteria are protective of olfactory impairment in juvenile salmon. © 2011 SETAC.
Jeffries M.K.S.,Miami University Ohio |
Claytor C.,GEI Consultants |
Stubblefield W.,Oregon State University |
Pearson W.H.,Pacific Northwest National Laboratory |
And 2 more authors.
Environmental Science and Technology | Year: 2013
Phototoxicity occurs when exposure to ultraviolet radiation increases the toxicity of certain contaminants, including polycyclic aromatic hydrocarbons (PAHs). This study aimed to (1) develop a quantitative model to predict the risk of PAH phototoxicity to fish, (2) assess the predictive value of the model, and (3) estimate the risk of PAH phototoxicity to larval and young of year Pacific herring (Clupea pallasi) following the Exxon Valdez oil spill (EVOS) in Prince William Sound, Alaska. The model, in which median lethal times (LT50 values) are estimated from whole-body phototoxic PAH concentrations and ultraviolet A (UVA) exposure, was constructed from previously reported PAH phototoxicity data. The predictive value of this model was confirmed by the overlap of model-predicted and experimentally derived LT50 values. The model, along with UVA characterization data, was used to generate estimates for depths of de minimiz risk for PAH phototoxicity in young herring in 2003/2004 and immediately following the 1989 EVOS, assuming average and worst case conditions. Depths of de minimiz risk were estimated to be between 0 and 2 m deep when worst case UVA and PAH conditions were considered. A post hoc assessment determined that <1% of the young herring population would have been present at depths associated with significant risk of PAH phototoxicity in 2003/2004 and 1989. © 2013 American Chemical Society.
Liao Y.,Kleinfelder , Inc. |
Meneses J.,GEI Consultants
NCEE 2014 - 10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering | Year: 2014
This paper presents the results of a study on characterizing site amplification of ground motions during the 2010 Mw 7.2 El Mayor-Cucapah earthquake using horizontal-to-vertical (H/V) spectral ratio method. The H/V spectral ratio shows peaks at about 0.2, 0.5, and 0.9 seconds for 2012 International Building Code (IBC) Site Classes B, C and D, respectively. The H/V spectral ratio technique predicts mean Fa=1.3 and Fv=1.7 for Class D sites and mean Fa=1.1 and Fv=1.3 for Class C sites. The two site classes show slightly smaller short-period amplification factors but substantially greater mid-period amplification factors compared with 2012 IBC code values. Sites with shear wave velocity in the upper 30 m (Vs30) between 180 and 250 m/s show similar amplification factors as 2012 IBC code values. These findings indicate that current 2012 IBC code may generally overestimate site amplification for both Site Classes C and D.
Jansen P.,GEI Consultants |
Sabulis M.,GEI Consultants |
Remediation | Year: 2016
In situ solidification (ISS) is a proven technology for remediation of upland site soils, but has not been thoroughly demonstrated for use in impacted underwater sediments. This article describes the first successful use of ISS techniques to solidify underwater sediments containing manufactured gas plant non-aqueous-phase liquid (NAPL). The techniques consisted of mixing cementitious grout with the sediments in situ to create a monolith that immobilized the contaminants, significantly decreased the hydraulic conductivity, and also vastly decreased contaminant leaching potential of the sediments. The success of this pilot demonstration project suggests that ISS may be a viable alternative for: sites requiring deep dredging; large volume projects on urban waterways where staging and amending areas are limited; sites with NAPL impacts that cannot be controlled during dredging; and sites where eventual NAPL breakthrough is anticipated if reactive caps are employed. The potential economic, environmental, and operational benefits of this technology will be discussed. This article focuses on the primary objectives of the pilot demonstration: to meet quantitative performance criteria for strength and hydraulic conductivity; to assess the leach performance of the solidified sediments; and to satisfy water quality parameters for turbidity, pH, and sheen. Approach/activities: The pilot study utilized a customized marine platform (modular floats, tug boats, etc.) and full-scale ISS equipment (auger rig, silos, etc.) and varied operational parameters to provide a range of data to assist in evaluating the feasibility and efficacy of the technology for use in similar environments and in planning future ISS projects on the water. Water quality controls and monitoring were implemented during the operation, and the study documented and evaluated the environmental disruption (short-term impacts) and costs of the application of the ISS process to contaminated aquatic sediments. © 2016 Wiley Periodicals, Inc.
Dela Cruz R.,Southern California Edison |
Blevins B.,Southern California Edison |
Karam C.,GEI Consultants
Association of State Dam Safety Officials, Dam Safety 2015 | Year: 2015
As dams across the United States are ageing, the risk of failure increases. Failures continue to happen due to natural and man-made events. When a failure occurs, it can be impossible to recover from. According to the Insurance Information Institute, up 40% of businesses affected by a natural or human-caused disaster never reopen. While there are programs at both Federal and State levels of government to help ensure the continuous safe operation of dams, it is important that a dam owner takes a holistic approach to Dam Safety Emergency Management and develop a program that will prevent and protect dams from all hazards that threaten them, as well as, ensure that the owner and community are fully able to respond to, and recover from, any incident that may occur. A comprehensive Dam Safety Emergency Management Program should include the five components of emergency preparedness as established by the Federal Emergency Management Association (FEMA). These components are prevention, protection, mitigation, response, and recovery. How much should be invested in an emergency program depends upon many factors such as regulatory requirements, business design, and how much risk a business is willing to tolerate. Since not all risk can be insured, an emergency program is a good way to manage those risks. One way to quickly buy down risk is to invest in improving a dam owner's Situational awareness. The U.S. Coast Guard defines situational awareness as "the ability to identify, process, and comprehend the critical elements of information about what is happening. More simply, it's knowing what is going on around you." Having improved situational awareness will reduce the time it makes to make a decision, improve the accuracy of that decision, and ensure that whatever strategies are being made before, during, or after an emergency event are made taking into account all the information at hand. Because of the importance of situational awareness when managing dams in remote locations across an expansive region, Southern California Edison (SCE) has developed on a pilot platform called a " Dam Information Management System" (DIMS), a web-based information sharing system that integrates available data from stakeholders and multiple emergency management partners to enable processing and displays of real-time disaster related data. DIMS will serve as a decision making tool to timely detect and evaluate emergency conditions for each dam to categorize the appropriate emergency response level. It leverages Geographic Information System (GIS) technology to allow visualization and analysis of relevant information to enable a more integrated operational approach during normal operations and emergency conditions. While the emphasis is primarily on emergency management, it also includes a document retrieval system that allows users to easily access the most up-to-date dam safety documents, inspection reports, and other activity related information for a specific dam. This paper aims to present to the dam safety community the: importance of situational awareness in emergency management, available situational awareness tools and resources from governmental and nongovernmental partners, and need for a collaborative partnership in sharing of information for effective situational awareness.
Finno R.J.,Northwestern University |
Arboleda-Monsalve L.G.,California State University, Long Beach |
Sarabia F.,GEI Consultants
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2015
Ground movements observed during foundation installation and basement construction of a residential 53-story RC tower are presented. The One Museum Park West building is located in Chicago, Illinois, and was developed using a combination of bottom-up methods, used for the construction of a central concrete core of the building, and top-down methods to build five levels of basements. The excavation extended 13-15 m below grade and was made through soft to medium-stiff clays. The building was supported by drilled shafts and a perimeter wall formed by secant piles that transitioned to tangent piles below the bottom of the cut. The system was laterally braced with RC floor slabs structurally connected to the secant pile walls and the RC core. Field performance data were collected by means of settlement points and inclinometers located close to the walls on two sides of the excavation. The construction sequence and attendant ground movements during each main activity are summarized. As much as 160 mm of settlement was recorded in the adjacent streets throughout construction. Wall and foundation installation accounted for approximately 35% of the total settlements during construction, whereas top-down construction of the basement resulted in approximately 40% of the total settlements. These data emphasize the importance of considering all construction activities when making predictions of ground movements adjacent to deep supported excavations. © 2014 American Society of Civil Engineers.
Iezzoni H.M.,GEI Consultants |
McCartney J.S.,University of California at San Diego
Geotechnical Testing Journal | Year: 2016
This study investigates how temperature affects the response of capacitance sensors used to measure the dielectric permittivity of unsaturated soils. The dielectric permittivity is strongly correlated with the volumetric water content, an important variable in understanding water flow processes in unsaturated soils. Although capacitance sensors have been used widely in laboratory and field applications, they have only recently been used to characterize thermally induced water flow in unsaturated soils during geothermal heat exchange processes. To date, no studies have characterized the effects of temperature on capacitance sensor output for dense, compacted soils. This paper describes a calibration methodology that was used to isolate the effects of temperature on the response of capacitance probes in compacted soils having different initial conditions (i.e., compaction water content and dry density). It was observed that changes in temperature of 26°C can lead to an increase in the measured dielectric permittivity of up to 24 % with no changes in volumetric water content of the soil. In addition to defining a soil-specific calibration equation to relate volumetric water content and dielectric permittivity under ambient temperature conditions, a correction equation was proposed for temperature effects. The capacitance sensor's response to changing temperatures was observed to be sensitive to both the initial volumetric water content and the initial density of the soil, and parameters were defined for both of these terms in the correction equation. Copyright © 2016 by ASTM International.