Walnut Creek, CA, United States
Walnut Creek, CA, United States

Time filter

Source Type

Locher H.,International Hydropower Association | Johannesson G.A.,National Energy Authority | Xuezhong Y.,China Institute of Water Resources and Hydropower Research | Phiri I.,Ministry of Energy and Water Development | And 11 more authors.
Water Alternatives | Year: 2010

The World Commission on Dams (WCD) has called for developers, governments, civil society, etc. to use its Strategic Priorities as a starting point for dialogue and initiatives to address issues regarding the development of dams. One very notable follow-up initiative has been led by the hydropower industry. The International Hydropower Association developed Sustainability Guidelines (IHA, 2004) and a Sustainability Assessment Protocol (IHA, 2006), and most recently has been involved in a two-year process with governments, NGOs and the finance sector to develop a broadly endorsed sustainability assessment tool based on review and update of the IHA Sustainability Assessment Protocol. This cross-sectoral process, known as the Hydropower Sustainability Assessment Forum (HSAF), has drawn on the knowledge base and many of the findings and recommendations of the World Commission on Dams, as well as a number of other developments in the last ten years. A fundamental premise of the work of the Forum is that an industry-driven and -owned initiative has far-reaching potential to influence performance in the hydropower sector. At the same time, the potential for the use of a broadly endorsed sustainability assessment tool for hydropower by those in other sectors is well recognised and aspired to by the Forum. This paper describes the work of the Forum up to August 2009 and the contents of the Draft Protocol released publicly in August 2009, and considers some of the commonalities and points of departure between this process and the WCD. The Forum's work on the Hydropower Sustainability Assessment Protocol is a work in progress, so this paper can describe but not give a full analysis of the work while it is in train.


Bedoya D.,MWH Global Inc. | Olander E.,MWH Global Inc. | Pisano W.,MWH Global Inc. | Carr D.,MWH Global Inc.
Journal of New England Water Environment Association | Year: 2015

Over the past 20 years, the city of Cambridge has taken a rigorous approach to combined sewer and stormwater management. In tandem with sewer separation, it is constructing drainage systems to relieve broad community flooding problems, address long-term operations and maintenance, and enhance water quality in local receiving waters. As a result, rivers are becoming cleaner, and in areas where stormwater management improvements have occurred, flooding has diminished measurably. In achieving this, Cambridge has met the Massachusetts Water Resources Authority's (MWRA) court-ordered start dates for the sewer separation work in the Alewife watershed area, exceeded the Massachusetts Department of Environmental Protection's (MassDEP's) expectations for removing illicit connections and common manholes, and become a regional leader in stormwater management. The city believes it has done this in a manner that, while at times unavoidably and extraordinarily disruptive, has been genuinely sensitive to and considerate of community needs. Since 1998, more than 20 large-scale infrastructure projects with a construction value of approximately $245 million were completed by the Cambridge Department of Public Works (CDPW) and a number of innovative, stormwater management approaches have been successfully implemented. Of the stormwater management projects executed by Cambridge, the Alewife Stormwater Wetland is the "gem." This project has won several engineering prizes for innovation, community enhancement, and flood attenuation, and is part of a larger sewer separation program in the Concord Avenue, Huron Avenue and Fresh Pond Parkway triangle, which is tributary to the CAM 004 combined sewer overflow (CSO) outfall at the Alewife Brook.


Collins D.R.,MWH Global Inc | Cain C.B.,MWH Americas Inc. | Poltorak M.R.,MWH Americas Inc. | Upson G.L.,MWH Americas Inc.
Remediation | Year: 2016

Site investigations at an oil and gas facility identified a highly acidic waste referred to as residual acid tar that resulted in the transport of dissolved nickel toward the point of compliance at concentrations that exceeded site environmental screening levels. Solidification/stabilization (S/S) via deep soil mixing was selected as the remedial approach and a mixture of ground granulated blast furnace slag cement and Portland cement was subjected to treatability testing to evaluate the reagent mix's ability to achieve treatment objectives. Results from the treatability test showed a cement mix dose of 21 percent was sufficient to raise the pH above the target of 6.0 and reduce dissolved nickel concentrations to below site screening levels in leachate from treated samples of residual acid tar and material impacted by residual acid tar. Cement mix doses of 21 percent or greater were sufficient to achieve target strengths in the unimpacted shallow overburden. However, none of the doses tested were able to achieve target strengths in the residual acid tar or peaty material impacted by the residual acid tar. Results showed soil strengths increased significantly when the pH in leachate from the treated samples approached 12, suggesting the presence of organic acids related to the peaty soils may interfere with the cement set. Recommendations from the study include additional treatability testing to evaluate pre-treatment with hydrated lime to satisfy acid neutralization requirements prior to dosing with the cement mix. ©2016 Wiley Periodicals, Inc. ©2016 Wiley Periodicals, Inc.


Cherchi C.,MWH Americas Inc. | Badruzzaman M.,MWH Americas Inc. | Oppenheimer J.,MWH Americas Inc. | Bros C.M.,MWH Global Inc | And 2 more authors.
Journal of Environmental Management | Year: 2015

Holistic management of water and energy resources is critical for water utilities facing increasing energy prices, water supply shortage and stringent regulatory requirements. In the early 1990s, the concept of an integrated Energy and Water Quality Management System (EWQMS) was developed as an operational optimization framework for solving water quality, water supply and energy management problems simultaneously. Approximately twenty water utilities have implemented an EWQMS by interfacing commercial or in-house software optimization programs with existing control systems. For utilities with an installed EWQMS, operating cost savings of 8-15% have been reported due to higher use of cheaper tariff periods and better operating efficiencies, resulting in the reduction in energy consumption of ~6-9%. This review provides the current state-of-knowledge on EWQMS typical structural features and operational strategies and benefits and drawbacks are analyzed. The review also highlights the challenges encountered during installation and implementation of EWQMS and identifies the knowledge gaps that should motivate new research efforts. © 2015 Elsevier Ltd.


Adelman M.J.,MWH Global Inc. | Weber-Shirk M.L.,Cornell University | Will J.C.,Agua Para El Pueblo | Cordero A.N.,Accenture | And 2 more authors.
Journal of Environmental Engineering (United States) | Year: 2013

Infrastructure for water treatment faces numerous challenges around the world, including the high failure rate of digital, electronic, pneumatic, and mechanical control systems due to their large number of components and their dependency on proprietary parts for repair. The development of more efficient, reliable, easily repaired water treatment controls that rely on simple fluidics rather than on complex systems has the potential to significantly improve the reliability of drinking water treatment plants, particularly for cities and towns in developing countries. A stacked rapid sand filter (SRSF) has been proposed as a more robust and sustainable alternative to conventional rapid sand filters because each filter can backwash at the same flow rate used for filtration without requiring pumps or storage tanks. While the concept of this filter has been demonstrated in previous studies, this paper presents a novel control system for the SRSF based on fluidics that eliminates the need for mechanized controls. The water level in the filter is regulated by a siphon pipe, which conveys flow during backwash and which contains an air trap to block flow during filtration. The state of the siphon pipe and the ensuing state of the filter are controlled by one small-diameter air valve. This fluidic control system was tested in pilot-scale experiments, which demonstrated its ability to set the mode of operation of the filter and served as the basis for the derivation of design equations. In addition, the first full-size SRSF was built at a municipal water plant in Honduras using this fluidic control system, which provided a full-scale demonstration of its effectiveness. This simple and robust control system shows promise as part of a sustainable rapid sand filtration process. © 2013 American Society of Civil Engineers.


PubMed | MWH Americas Inc., Johns Hopkins University and MWH Global Inc.
Type: | Journal: Journal of environmental management | Year: 2015

Holistic management of water and energy resources is critical for water utilities facing increasing energy prices, water supply shortage and stringent regulatory requirements. In the early 1990s, the concept of an integrated Energy and Water Quality Management System (EWQMS) was developed as an operational optimization framework for solving water quality, water supply and energy management problems simultaneously. Approximately twenty water utilities have implemented an EWQMS by interfacing commercial or in-house software optimization programs with existing control systems. For utilities with an installed EWQMS, operating cost savings of 8-15% have been reported due to higher use of cheaper tariff periods and better operating efficiencies, resulting in the reduction in energy consumption of 6-9%. This review provides the current state-of-knowledge on EWQMS typical structural features and operational strategies and benefits and drawbacks are analyzed. The review also highlights the challenges encountered during installation and implementation of EWQMS and identifies the knowledge gaps that should motivate new research efforts.


Jennings A.A.,Case Western Reserve University | Hanna A.,MWH Global Inc.
International Journal of Environment and Waste Management | Year: 2010

This manuscript describes a database of US state regulatory guidance values assembled to examine the guidance applied to the most commonly regulated surface soil contaminants. Guidance values were identified for 994 different contaminants, but there is considerable variability in the number of contaminants regulated by each state and in the values applied to contaminants. Guidance values for the 40 most-regulated organics vary by an average of four orders of magnitude. Details are presented for guidance applied to naphthalene, benzene, toluene, ethylbenzene, dimethylbenzene, Lindane, phenol, trichloroethylene, benz[a]anthracene, and methoxychlor to illustrate statistical properties of value variation. Copyright © 2010 Inderscience Enterprises Ltd.


Weng S.,Johns Hopkins University | Luo Y.,U.S. Department of Agriculture | Li J.,U.S. Department of Agriculture | Li J.,Huazhong Agricultural University | And 4 more authors.
Food Control | Year: 2016

For the fresh-cut produce industry, a critical area of concern is potential pathogen cross-contamination during wash operations when wash water is reused and re-circulated in wash systems continuously imputed with fresh-cut produce. However, little research has focused on the chemical properties of wash water. Organic input from residual soil and vegetable material deteriorates water quality and creates increasing chlorine demand within this wash water. This study evaluated the origins of chlorine demand input and chlorine decay kinetics of fresh-cut produce wash water. Using a model system, vegetable juice released per kg of processed produce for shredded romaine lettuce, shredded iceberg lettuce, shredded carrot and baby spinach was 82.1 mL/kg, 94.5 mL/kg, 158 mL/kg, and 2.26 mL/kg, respectively. Batch water analysis revealed a rapid reaction between constituents in the wash water and chlorine where over a 90 min observation period, 50% of chlorine demand occurred within first 5 min, underscoring the challenge for any water treatment process to reduce chlorine demand once vegetables are deposited into washing systems. Moreover, the results also showed sustained chlorine demand over 90-min periods, indicating an accumulative effect on chlorine consumption with continuous organic input. Additionally, HPLC-SEC analysis showed that the constituents contributing to chlorine demand are predominantly dissolved small molecules (<3400 Da), which will challenge water reuse treatment approaches. This study provides quantitative information of chlorine demand origins and chlorine decay kinetics in wash water and provides baseline data critical for integrating water reuse in the fresh produce processing industry. © 2015 Elsevier Ltd.


Morway E.D.,U.S. Geological Survey | Niswonger R.G.,U.S. Geological Survey | Triana E.,MWH Global Inc.
Environmental Modelling and Software | Year: 2016

Advanced modeling tools are needed for informed water resources planning and management. Two classes of modeling tools are often used to this end-(1) distributed-parameter hydrologic models for quantifying supply and (2) river-operation models for sorting out demands under rule-based systems such as the prior-appropriation doctrine. Within each of these two broad classes of models, there are many software tools that excel at simulating the processes specific to each discipline, but have historically over-simplified, or at worse completely neglected, aspects of the other. As a result, water managers reliant on river-operation models for administering water resources need improved tools for representing spatially and temporally varying groundwater resources in conjunctive-use systems. A new tool is described that improves the representation of groundwater/surface-water (GW-SW) interaction within a river-operations modeling context and, in so doing, advances evaluation of system-wide hydrologic consequences of new or altered management regimes. © 2016 Elsevier Ltd.


Newbery M.J.,MWH Global Inc. | Krause A.J.,MWH Global Inc.
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012

This paper provides an overview of the key design aspects of the $3.5 billion Panama Canal Third Set of Locks design-build project. The design of the project is being prepared by MWH as lead of the CICP Consultores Internacionales JV Design Team for Grupo Unidos Por el Canal (GUPC) the construction JV. The paper presents a summary of the concept design prepared by the Owner, the Panama Canal Authority (ACP), bid technical specifications, and the consequent tender design development that led to the highest-ranked technical proposal and lowest design-build price. Also described in detail are several of the critical design elements of the project, specifically: the lock filling and emptying studies, design of the lock concrete structures (lock chambers and lock heads), and design of the unique "rolling door" type lock gates. The paper concludes with a summary of design advances that are being incorporated into the Third Set of Locks. © 2012 ASCE.

Loading MWH Global Inc collaborators
Loading MWH Global Inc collaborators