MacBroom J.G.,Milone and MacBroom Inc.
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012
Scour analysis is a critical part of many river restoration and rehabilitation projects located in the vicinity of existing bridges, retaining walls, and subsurface utility infrastructure. The removal of grade control systems, fish passage barriers, and abandoned or unsafe dams may result in altering riverbed stability or creating upstream headcuts that could influence bridges. Other types of physical restoration projects to renaturalize rivers may alter bed gradients, revise channel alignment, change flow velocities, or modify sediment transport. Careful hydraulic studies are required to assess the potential for short-term scour and long-term degradation or aggradation. Traditional methods developed for the design and evaluation of transportation bridges such as Federal Highway Administration guidelines (HEC-18) are also applied at restoration sites. However, there has been concern about erratic scour depth predictions, so supplemental techniques should be used to check results. They include use of U.S. Geological Survey bridge scour field data, regional performance of similar bridges and substrates, and sediment transport models. Immediately following Hurricane Irene, post disaster river restoration assistance included inspecting 50 bridges in three states, leading to 12 closures largely due to scour and sediment problems. Several interesting cases were assessed, including a dam removal situation, a braided channel, and aggradation at bridges. © 2012 ASCE.
MacBroom J.G.,Milone and MacBroom Inc. |
MacBroom J.G.,Yale University
World Environmental and Water Resources Congress 2011: Bearing Knowledge for Sustainability - Proceedings of the 2011 World Environmental and Water Resources Congress | Year: 2011
The practice of river management and restoration is a complex field that requires knowledge drawn from hydrology, hydraulics, fluvial morphology, sediment processes, water chemistry, and aquatic ecology. River restoration is increasingly applied at a watershed scale, rather than small reach scales, and involves public participation and community involvement. As a result, river restoration practitioners need to have broad interdisciplinary training to supplement what has historically and traditionally been an emphasis on only empirical experience and narrow scientific disciplines. Examples of various river restoration educational programs are provided below. © 2011 ASCE.
Schiff R.,Milone and MacBroom Inc. |
Benoit G.,The New School |
Macbroom J.,Milone and MacBroom Inc.
River Research and Applications | Year: 2011
Stream rehabilitation and enhancement projects in the Norwalk River (urban-forest watershed) and Merrick Brook (agriculture-forest watershed) were evaluated. Instream structure installation, streambank stabilization and meander re-creation were performed 2-5 years before monitoring. Physical, chemical and biological variables were monitored at control, enhanced (treatment sites originally controls), impaired and rehabilitated (treatment sites originally impaired) sites for three field seasons to evaluate the projects and formulate monitoring strategies. Small improvements in local habitat and macroinvertebrate assemblages were observed at rehabilitated sites on the Norwalk River however control conditions were not attained. Changes to stream health were less evident at the reach scale suggesting that watershed processes that form and maintain habitat were too altered for more widespread recovery. A localized sediment source from a failing streambank was eliminated from Merrick Brook protecting the abundant nearby quality habitat, yet fining occurred at the rehabilitation site due to hydraulic changes leading to localized shifts in macroinvertebrate assemblages. Single-season sampling created a useful snapshot to compare enhanced and rehabilitated sites to control and impaired sites. We recommend a tiered sampling strategy where effectiveness monitoring may include a detailed effort at many sites over a short time (as performed here), a relatively low level of detail (e.g. a rapid assessment) at an intermediate number of sites over a short time, and a detailed long-term monitoring at few sites (e.g. before-after-control-impact, BACI). More research is needed to continue the trend of increased project evaluation to advance the science and application of stream restoration. © 2010 John Wiley & Sons, Ltd.
Jiang Z.,Front Street Consulting |
Kim S.J.,Keimyung University |
Plude S.,Milone and MacBroom Inc. |
Christenson R.,University of Connecticut
Smart Materials and Structures | Year: 2013
Magneto-rheological (MR) fluid dampers can be used to reduce the traffic induced vibration in highway bridges and protect critical structural components from fatigue. Experimental verification is needed to verify the applicability of the MR dampers for this purpose. Real-time hybrid simulation (RTHS), where the MR dampers are physically tested and dynamically linked to a numerical model of the highway bridge and truck traffic, provides an efficient and effective means to experimentally examine the efficacy of MR dampers for fatigue protection of highway bridges. In this paper a complex highway bridge model with 263 178 degrees-of-freedom under truck loading is tested using the proposed convolution integral (CI) method of RTHS for a semiactive structural control strategy employing two large-scale 200 kN MR dampers. The formation of RTHS using the CI method is first presented, followed by details of the various components in the RTHS and a description of the implementation of the CI method for this particular test. The experimental results confirm the practicability of the CI method for conducting RTHS of complex systems. © 2013 IOP Publishing Ltd.
MacBroom J.G.,Milone and MacBroom Inc. |
Schiff R.,Milone and MacBroom Inc.
GSA Reviews in Engineering Geology | Year: 2013
The removal of obsolete and unsafe dams for safety, environmental, or economic purposes frequently involves the exploration of sediments trapped within the impoundment and the subsequent assessment of sediment management needs and techniques. Sediment management planning requires a thorough understanding of the watershed's surficial geology, topography, land cover, land use, and hydrology. The behavior of sediments is influenced by their age, consolidation, and stratigraphy. All watersheds have a history that helps forecast sediment loads, quality, gradation, and stratigraphy. Impounded sediment deposits may include coarse deltas and foreset slopes, fine or coarse bottom deposits, cohesive or organic matter, and wedge deposits immediately behind the dam. Some watersheds have anthropogenic pollutants from agricultural activities, mining, industries, or urban runoff. The volume and rate of sediment release during and after small dam removal can be limited by active management plans to reduce potential downstream impacts. Management strategies include natural erosion, phased breaches and drawdowns, natural revegetation of sediment surfaces, pre-excavation of an upstream channel, hazardous waste removal or containment, flow bypass plans, and sediment dredging. © 2013 Geological Society of America. All rights reserved.