Denver, CO, United States
Denver, CO, United States

Time filter

Source Type

Guo J.C.Y.,University of Colorado at Denver | Blackler G.E.,University of Colorado at Denver | Earles T.A.,Wright Water Engineers Inc. | MacKenzie K.,Master Planning and Criteria Development
Journal of Environmental Engineering | Year: 2010

In practice, the challenge of storm-water low-impact-development (LID) design is often related to how to quantify the effectiveness of a LID layout. In this study, the watershed imperviousness was chosen as a basis to evaluate the performances of various LID designs. Often, LID designs apply cascading planes to drain the runoff flow from the upstream impervious area to the downstream pervious area. In this study, the conventional area-weighting method is revised with a pavement-area-reduction factor (PARF) to produce the effective imperviousness. PARF is employed as an incentive index to quantify the on-site runoff volume reduction and cost savings from downsized sewers. Two sets of PARF are derived: conveyance-based and storage-based LID designs. The conveyance-based LID approach is to drain runoff flows on various porous surfaces while the storage-based LID approach is to temporarily store runoff flows in an on-site basin. For a specified LID layout, the PARF provides a consistent basis to translate the infiltration and storage effects into the reduction on the area-weighted imperviousness. The nondimensional governing equation derived in this paper indicates that the PARF depends on the ratio of the soil infiltration rate to rainfall intensity, the ratio of receiving pervious area to upstream impervious area, and the on-site storm-water storage capacity. The PARF serves as a basis for the engineers, planners, and/or developers to select a LID design and also for regulatory agencies to assess meritorious credits for cost savings. © 2010 ASCE.

Guo J.C.Y.,University of Colorado at Denver | Jones J.E.,Wright Water Engineers Inc. | Earles A.,University of Colorado at Denver
Journal of Irrigation and Drainage Engineering | Year: 2010

As recommended, culvert entrances in urban areas should be protected with a rack or a grate because urban flood flows are quick, concentrated, and fast. Safety around storm-water facilities is an increasing concern for the public. Many forensic cases indicate that a trash rack at the entrance can prevent a human body from being washed into the culvert pipe, but on the other hand, a trash rack increases the flow velocity and results in a pinning force on the human body landed on the rack. While having a trash rack at a culvert entrance has the potential to result in a pinning force and to accumulate trash/debris, the public safety benefit of a trash rack in preventing a person from being drawn into an underground conduit outweigh the risks of the potential pinning force and/or trash/debris blockage. The conventional approach can only provide the total external force acting on a culvert-rack system, including the reaction forces from the wing walls and the rack with or without blockage. This study presents a new method of superimposition that can solve the external forces one by one progressively. Results from the case study indicate that the hydrostatic force due to the high headwater in front of the culvert entrance is mostly balanced by the reaction force from the wing walls. The pinning force on the submerged trash rack is mainly the response to the change in the flow momentum force. In comparison, the pinning force is much smaller than the total external force. A pinning force is a normal force on the rack surface. The effort to escape from being pinned on the trash rack is to overcome the friction along the rack surface. © 2010 ASCE.

Guo J.C.Y.,University of Colorado at Denver | Jones J.,Wright Water Engineers Inc.
Journal of Irrigation and Drainage Engineering | Year: 2010

The high design standards for the preservation of the urban water environment result in more detention basins in residential areas. The steep channel and outfall pipe from a detention basin can be hazardous to children and small animals. During an event, a trapped person may flow with water toward the outfall entrance. When the outfall pipe is gradually blocked, the flow force acting on the blocking body can be pinning at the beginning to eventually deadly. It is not clear as to how to quantify the pinning force on the block during the closure of flow because the number of unknown forces is greater than the number of equations for force balance. This paper presents a new approach using the method of superposition to calculate the pinning force with and without a blockage at the culvert entrance. The analysis conducted in this paper verifies that the pinning force on the clogging block is dominated by the flow dynamic force until the flow becomes discontinued. As soon as the hydrostatic force is developed, the pinning force can be lethal. This study confirms that an outfall pipe shall be protected by a trash rack with its surface area 4 times the culvert opening area. As long as the continuity of flow is sustained by the blocked rack, the hydrostatic force will not be developed or a chance for survival remains. © 2010 ASCE.

Pitt R.,University of Alabama | Clary J.,Wright Water Engineers Inc.
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012

Stormwater bacteria data are challenging to analyze for several reasons:•highly variable observation levels (more so than for any other commonly monitored stormwater constituent)•frequent right-censored data (very high levels can exceed the upper limit of the method being used)•non-conservative behavior can cause unusual observations and storage problems during sample collection•sensitive to environmental conditions (especially temperature)•most analytical methods have a limited range in bacteria levels that can be quantified In addition, traditional bacteria data reporting is usually expressed as a geometric mean in order to moderate the effects of periodic very high observed bacteria levels (most bacteria standards or criteria are expressed using geometric means, for example), which hinder statistical analyses of existing information. These issues therefore hinder the types of statistical analyses that can be conducted using most stormwater bacteria data. However, many of these problems can be overcome by careful sampling and proper selection of the analytical method, as noted below. Sampling plans must consider the sampling locations appropriate for the project objectives. Bacteria sources vary greatly in urban areas, but high levels can be observed in many locations. Roof runoff water can have very high levels during summer and spring months if heavily covered by trees, due to the increased numbers of birds and squirrels that can reside above the roof surfaces. During colder months, many of these animals may migrate, hibernate, or become inactive, resulting in significantly decreased bacteria levels in the roof runoff. Soil bacteria levels can remain high in areas where urban wildlife or pets defecate, with runoff bacteria levels dependent on the amount of erosion occurring. Bacteria levels in runoff from paved areas can also be high in areas where pets are "walked." Residential areas and park pathways usually have larger bacteria levels than industrial areas, for example. Outfall stormwater samples are affected by the relative contributions of flows from the different areas which vary mostly according to rain characteristics. Therefore, an experimental design for bacteria sampling must consider these varying sources and seasonal conditions, requiring many samples over an extended period. © 2012 ASCE.

Clary J.,Wright Water Engineers Inc. | Quigley M.,330 Beacon St. | Poresky A.,55 SW Yamhill St. | Earles A.,Wright Water Engineers Inc. | And 3 more authors.
Journal of Irrigation and Drainage Engineering | Year: 2011

Low impact development (LID) strategies are being encouraged in many communities as an approach to reduce potential adverse impacts of development on receiving streams. Many questions exist regarding how well various LID strategies perform in different settings, just as similar questions have been raised regarding performance of traditional stormwater best management practices (BMPs). Whereas historical focus on BMP performance has been water quality concentrations or loads, characterization of volume reduction benefits for both conventional and LID practices is increasingly an objective of researchers and stormwater managers. More than a decade ago, Urban Water Resources Research Council (UWRRC) members worked to develop a set of standardized monitoring and reporting protocols for traditional BMPs and to establish a master database for the purpose of evaluating BMP performance and the factors affecting performance. This effort culminated in the International Stormwater BMP Database (, which contains data for more than 360 BMPs and continues to operate as a clearinghouse for stormwater BMP data and performance analyses. During 2008-2009, the International Stormwater BMP Database project expanded to better integrate LID into the database and develop a set of metrics that can be used to characterize BMP performance with regard to surface runoff volume reduction. This paper provides a condensed overview and progress report on the LID-focused effort, including the following topics: (1) monitoring guidance for LID at the overall site development level, (2) an overview of recent changes to the International Stormwater BMP Database to better accommodate LID studies, (3) a summary of LID studies currently included in the database, and (4) a proposed approach for evaluating performance of LID studies with regard to reducing surface runoff volumes. © 2011 American Society of Civil Engineers.

Wolfram P.J.,Los Alamos National Laboratory | Lorenz W.F.,Los Alamos National Laboratory | Lorenz W.F.,Wright Water Engineers Inc
International Journal for the History of Engineering and Technology | Year: 2016

Ancient Roman engineers are famous for their use of arcades, or arched bridges, to elevate roads and aqueducts across valleys. The Romans first designed and built arches using stone blocks and then later changed to special concrete construction. In this paper, we illustrate how early unmortared arches could have been built using geometric design principles. This simplified analysis is sufficient to demonstrate, via retrospective analysis, the need for reconstruction efforts for arches violating these design criteria. Well-preserved remnants at the Simian Bridge and Vallon des Arcs arcades, located in southern France near Arles, are excellent examples of Roman arch engineering and are used as case studies to understand geometric arch design in practice. These arcades are vital parts of a larger aqueduct system used to provide the waterpowered industrial Barbegal Mill and city of Arles with water in the first century A.D. Analysis of currently standing arches implies that Roman engineers may have relied extensively upon geometrical rules of thumb for design of these structures. In particular, modern stability analysis demonstrates the effectiveness of geometrical rules of thumb in determining structural failure requiring reconstruction at the Simian Bridge. The reconstruction that exists at the Simian bridge shows a shift from stone blocks to concrete. This shift may have occurred as a result of the Roman engineers' increased awareness of geometrical criteria for arch design. © 2016 The Newcomen Society for the Study of the History of Engineering & Technology.

Keyes J.,Wright Water Engineers Inc.
41st International Erosion Control Association Annual Conference 2010 | Year: 2010

This presentation is a nuts-and-bolts account of the benefits and requirements of a successful auditing program for stormwater from construction sites. Covered topics include: what deficiencies in Stormwater Management Plans and BMP implementation are commonly cited by regulators; samples of fines levied; the key components and considerations of an audit program; and regulatory requirements for a construction site stormwater auditing program. Case studies from various industries are described. Copyright © (2010) by the International Erosion Control Association.

Wright K.R.,Wright Water Engineers Inc.
Practice Periodical on Structural Design and Construction | Year: 2013

The remarkable construction skills of the Inca are manifested in the superb site preparation, foundation design, and drainage of Machu Picchu. Decade-long field studies at the pre-Columbian archaeological site of Machu Picchu revealed that the Inca possessed the ability to prepare for structures that endure. This is evident in the vast amount of Inca construction that still exists for engineers to study and admire. Inca construction was sustainable because of their high standard of care, even in the absence of a written language, use of the wheel, or availability of iron or steel. This paper contains examples of good ancient site preparation, foundations, and drainage at Machu Picchu and details of a foundation failure and an ancient landslide. These examples serve to illustrate the site's challenging conditions for construction and the remarkable skills of the Inca engineers in addressing these difficulties. © 2013 American Society of Civil Engineers.

Keyes J.,Wright Water Engineers Inc.
43rd International Erosion Control Association Annual Conference 2012 | Year: 2012

This presentation will cover the main changes in the proposed EPA CGP and strategies for achieving and maintaining compliance with the permit. Main topics that will be discussed include buffer protection, stabilization, water quality and required BMPs.

Lorenz W.F.,Wright Water Engineers Inc. | Wolfram P.J.,Stanford University
Journal - American Water Works Association | Year: 2012

The Wright Paleohydrological Institute (WPI) studied the Barbegal water system, France, to study of its mineral deposits in rocklike layers formed over millennia, providing a knowledge of the quality of ancient water sources and how early engineers designed and operated public works water systems. The results of the water quality analyses show that the total hardness of the spring water ranges from 310 to 320 mg/L as CaCO3, indicating a fairly high degree of hardness. Measurement of water source signatures in the detrital layers indicate that at first the aqueducts in the Barbegal system were operated separately, with the north aqueduct supplying Arelate's domestic uses and the south aqueduct powering the mill complex. The study also found that water that would have originally been delivered to Arelate was redirected for industrial use in the Barbegal water mill as a result of changing water uses.

Loading Wright Water Engineers Inc. collaborators
Loading Wright Water Engineers Inc. collaborators