GHD Inc.

Raleigh, NC, United States
Raleigh, NC, United States
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Syachrani S.,Oklahoma State University | Jeong H.S.,Oklahoma State University | Chung C.S.,GHD Inc.
Journal of Pipeline Systems Engineering and Practice | Year: 2011

One of the key components in successfully implementing asset-management programs is to have accurate and reliable deterioration models for the assets because the deterioration models are the core computational basis for predicting and prioritizing future maintenance, rehabilitation, or replacement activities of the assets. Many large and advanced utilities have put extensive efforts into collecting condition assessment data of their assets since the late 1990s. This change has posed new challenges in developing deterioration models. This paper presents a framework for developing dynamic deterioration models that can avoid the uniform treatment of the entire sewer pipe network by using the clustering and filtering process on the basis of location-related attributes and operational conditions. The dynamic deterioration models are dynamic because they are dual models for a single sewer network; one model is for individual prediction and the other for group prediction. The performance and benefits of the dynamic deterioration models are discussed with the conventional deterioration models developed in this study for comparison purposes. More realistic and reliable decisions can be made by using the dynamic deterioration models, which can translate into accountable short-term and long-term funding strategies for sustainable infrastructure asset management. © 2011 American Society of Civil Engineers.


Syachrani S.,GHD Inc. | Jeong H.S.,Iowa State University | Chung C.S.,GHD Inc.
Journal of Performance of Constructed Facilities | Year: 2013

Asset management provides a managerial decision-making framework for public agencies to monitor, evaluate, and make informed decisions about how to best maintain vital civil infrastructure assets. Among many steps required for implementing asset management, developing an accurate deterioration model is one of the key components because it helps infrastructure agencies predict remaining asset life. The accuracy of deterioration models highly depends on the quality of input data and the computational technique used in data analysis. Among many options of computational techniques, a decision tree offers the combination of visual representation and sound statistical background. The visual representation enables the decision maker to identify the relationship and interdependencies of each decision and formulate an appropriate prediction. This study developed a decision tree-based deterioration model for sewer pipes. The performance of the new model is then compared with conventional regression- and neural networks-based models that are also developed using the same data sets. The result shows that the decision tree outperformed other techniques in terms of accuracy (error rate). The paper also discusses different deterioration patterns of different categories of pipes. © 2013 American Society of Civil Engineers.


Syachrani S.,GHD Inc. | Jeong H.D.,Iowa State University | Chung C.S.,GHD Inc.
Water Science and Technology | Year: 2013

For effective management of water and wastewater infrastructure, the United States Environmental Protection Agency (US-EPA) has long emphasized the significant role of risk in prioritizing and optimizing asset management decisions. High risk assets are defined as assets with a high probability of failure (e.g. soon to fail, old, poor condition) and high consequences of failure (e.g. environmental impact, high expense, safety concerns, social disruption). In practice, the consequences of failure are often estimated by experts through a Delphi method. However, the estimation of the probability of failure has been challenging as it requires the thorough analysis of the historical condition assessment data, repair and replacement records, and other factors influencing the deterioration of the asset. The most common predictor in estimating the probability of failure is calendar age. However, a simple reliance on calendar age as a basis for estimating the asset's deterioration pattern completely ignores the different aging characteristics influenced by various operational and environmental conditions. This paper introduces a new approach of using 'real age' in estimating the probability of failure. Unlike the traditional calendar age method, the real age represents the adjusted age based on the unique operational and environmental conditions of the asset. Depending on the individual deterioration pattern, the real age could be higher or lower than its calendar age. Using the concept of real age, the probability of failure of an asset can be more accurately estimated. © IWA Publishing 2013.


Singh A.,GHD Ltd | Lutchman R.,GHD Ltd | Ponce I.,0 Peel Center Dr | Motala I.,0 Peel Center Dr
Pipelines 2016: Out of Sight, Out of Mind, Not Out of Risk - Proceedings of the Pipelines 2016 Conference | Year: 2016

Growth projections indicate that the Regional Municipality of Peel (the Region) will need to supply over 2.5 million residential and commercial customers with a reliable and high quality supply of drinking water over the next 20 years. In order to achieve these customer levels of services while balancing cost and risk of service, the Region utilized a risk based approach to managing its transmission and sub transmission pipes (water supply pipes) to inform decisions related to maintenance, renewal and capital programming activities with the end goal of achieving established customer level of service targets for water supply. The outcomes of the risk assessment allowed the Region to identify critical water supply pipes; support business justification for short, medium and long term expenditures; use net present value (NPV) economic analysis to identify the lowest cost mitigation options; and develop a consistent and transparent risk based approach to managing its transmission and sub transmission mains. © 2016 ASCE.


Grabow G.L.,North Carolina State University | Ghali I.E.,North Carolina State University | Huffman R.L.,North Carolina State University | Miller G.L.,North Carolina State University | And 2 more authors.
Journal of Irrigation and Drainage Engineering | Year: 2013

Increasing competition for water and the desire for high-quality turfgrass require sound irrigation water management. The main objective of this study was to evaluate two types of commercially available irrigation control technologies: one based on evapotranspiration (ET) estimates and the other based on feedback from a soil-moisture sensor (SMS). Irrigation treatments were combinations of controller technology: a timer-based standard controller system (TIM), an add-on (1 set point) SMS system (SMS1), and an evapotranspiration (ET)- based system (ETB), and watering frequency: weekly, twice per week, and daily (1, 2, and 7 days per week, respectively) plus a 10th treatment of an on-demand (2 set point) SMS system (SMS2). Both irrigation efficiency and adequacy were best for the SMS2 treatment when averaged over all three years. The SMS1 treatment provided good irrigation efficiency, but irrigation adequacy suffered, most noticeably with the twice per week treatment. The ET treatment provided good irrigation adequacy, but had the poorest irrigation efficiency. SMS treatments resulted in average water savings of 39% in SMS1 treatments and 24% in the SMS2 treatment compared to the timer-based treatments, whereas the ET treatments applied 11% more water, on average, than the timer-based treatments. The weekly SMS1treatment applied the least amount of water (10 mmweek-1), whereas the twice per week ET treatment applied the most water (26 mmweek-1). © 2013 American Society of Civil Engineers.


Siemers-Kennedy L.C.,GHD Inc.
Pipelines 2015: Recent Advances in Underground Pipeline Engineering and Construction - Proceedings of the Pipelines 2015 Conference | Year: 2015

An extended period calibration was performed for Sydney Water Corporation in Australia, a regional utility which serves 4.6 million people and manages 13,000 miles of water mains. The purpose of the project was to calibrate existing models to maintain an accurate representation of the water distribution system, customer demand patterns, and controls. The calibrated models would then be able to be used by the utility for many purposes including future growth planning, operations optimization, water quality modeling, and incident management. The calibration process consisted of updating models based on the most recent geospatial data of the network assets, updating the demands from the customer usage database, and updating the controls from the SCADA system. The calibration tolerance of +/-1 m difference between observed and measured hydraulic grade over a 24-hour period was achieved for the majority of calibration points. In order to achieve calibration, the boundary conditions and initial settings were updated based on measured data, the control settings were updated, and the demands were updated to match the demand patterns observed on the calibration day. In some cases additional modifications were needed to achieve the calibration tolerance, such as: pump curve adjustment, valve diameter adjustment, pipe roughness coefficient adjustment, and valve operational status. Identifying these operational issues as a result of the calibration process provided a benefit to the utility and allowed them to focus field efforts on particular areas, such as underperforming pumps and water mains with potential closed valves or other restrictions. © 2015 ASCE.


Drainville M.R.,GHD Inc. | Wong K.,GHD Inc.
Journal of New England Water Environment Association | Year: 2013

The Chatham Water Pollution Control Facility (WPCF), became one of the first wastewater treatment facilities permitted to remove nitrogen to the limit of technology in Massachusetts. Upgrades were started in early 2010 to achieve an effluent annual average total nitrogen (TN) of 3 mg/L based on the total maximum daily loads (TMDLs) set for the surrounding coastal estuaries by the Massachusetts Department of Environmental Protection (MassDEP). Along with the WPCF upgrade, the collection system was expanded as part of the town's Comprehensive Wastewater Management Plan (CWMP) implementation. Both the WPCF and collection system projects received funding from the American Recovery and Reinvestment Act (ARRA) of 2009. Sustainability concepts and practices were incorporated into the WPCF and the pump station designs Construction of the WPCF improvements reached substantial completion in mid-April 2011, and the facility has been achieving an average of less than 3 mg/L effluent TN since steady state operation was achieved.


McGovern T.,Hampton Roads Sanitation District | Sullivan B.,GHD Inc.
AWWA/WEF Utility Management Conference 2013 | Year: 2013

Implementing, sustaining, and improving a Computerized Maintenance Management System (CMMS) or an Enterprise Asset Management System (EAMS) is a continual process that requires many factors to achieve excellent results and benefits. This continuous process can be similar to a long journey that involves significant advanced planning and the ability to make adjustments along the way. Throughout this presentation, specific steps will be highlighted that were taken by the Hampton Roads Sanitation District (HRSD) during this journey to keep their CMMS evolving to meet their changing needs. The results HRSD has achieved along the way in the journey towards CMMS excellence will also be discussed. © 2013 American Water Works Association.


Lewis C.,GHD Inc. | Serrahn C.,GHD Inc.
Ports 2016: Port Planning and Development - Papers from Sessions of the 14th Triennial International Conference | Year: 2016

The objective of the fender system upgrade at a raw sugar offloading terminal was to replace the dock's existing antiquated and damaged fendering system with a new and more effective fendering system. This improvement provides the means to preserve, protect, and extend the useful life of the existing dock; provide greater protection of facility's structural integrity; allow for safer cargo ship berthing and protection of vessel hulls; and improve water quality. This dock facility serves as a berthing, mooring and loading/off-loading facility for bulk sugar vessels. Over time, the size of bulk sugar vessels has increased, creating greater kinetic energy demands on the existing fendering system and making a berthing overload more likely. GHD performed structural condition assessments of the dock, performed berthing analyses and design for the design cargo vessel. The structural concrete repairs and replacement fender system were designed to be installed within the short periods available between cargo vessels calling at the dock. © ASCE.


Apparatuses and methods for anaerobic digestion of high-solids waste and the removal of hydrogen sulfide from a biogas are provided. The methods may include and the apparatuses may be used for moving the solid waste in a corkscrew-like fashion through a closed container. The method may further include moving the high-solids waste into contact with a heating device to facilitate the corkscrew-like movement. Other methods and apparatuses may use at least one of a partition and a conduit from which liquid or gas is discharged. The invention also relates to methods and apparatuses for reducing the amount of H_(2)S in a biogas produced from an anaerobic digester.

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