Tài liệu International conference on sustainable infrastructure 2017 technology

Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. International Conference on Sustainable Infrastructure 2017 TECHNOLOGY Proceedings of the International Conference on Sustainable Infrastructure 2017 > New York, New York > October 26–28, 2017 EDITED BY Lucio Soibelman, Ph.D. Feniosky Peña-Mora, Sc.D. Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. INTERNATIONAL CONFERENCE ON SUSTAINABLE INFRASTRUCTURE 2017 TECHNOLOGY PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON SUSTAINABLE INFRASTRUCTURE 2017 October 26–28, 2017 New York, New York SPONSORED BY Committee on Sustainability of the American Society of Civil Engineers EDITED BY Lucio Soibelman, Ph.D. Feniosky Peña-Mora, Sc.D RESTON, VIRGINIA Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Published by American Society of Civil Engineers 1801 Alexander Bell Drive Reston, Virginia, 20191-4382 www.asce.org/publications | ascelibrary.org Any statements expressed in these materials are those of the individual authors and do not necessarily represent the views of ASCE, which takes no responsibility for any statement made herein. No reference made in this publication to any specific method, product, process, or service constitutes or implies an endorsement, recommendation, or warranty thereof by ASCE. The materials are for general information only and do not represent a standard of ASCE, nor are they intended as a reference in purchase specifications, contracts, regulations, statutes, or any other legal document. ASCE makes no representation or warranty of any kind, whether express or implied, concerning the accuracy, completeness, suitability, or utility of any information, apparatus, product, or process discussed in this publication, and assumes no liability therefor. The information contained in these materials should not be used without first securing competent advice with respect to its suitability for any general or specific application. Anyone utilizing such information assumes all liability arising from such use, including but not limited to infringement of any patent or patents. ASCE and American Society of Civil Engineers—Registered in U.S. Patent and Trademark Office. Photocopies and permissions. Permission to photocopy or reproduce material from ASCE publications can be requested by sending an e-mail to [email protected] or by locating a title in ASCE's Civil Engineering Database (http://cedb.asce.org) or ASCE Library (http://ascelibrary.org) and using the “Permissions” link. Errata: Errata, if any, can be found at https://doi.org/10.1061/9780784481219 Copyright © 2017 by the American Society of Civil Engineers. All Rights Reserved. ISBN 978-0-7844-8121-9 (PDF) Manufactured in the United States of America. International Conference on Sustainable Infrastructure 2017 Preface THE CHALLENGE Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. The 2017 International Conference on Sustainable Infrastructure focused on developing roadmaps to address the UN Sustainability Goals of developing Sustainable cities and building resilient infrastructure as well as the NAE Grand Challenge to "restore and improve urban infrastructure," all while supporting the ASCE Grand Challenge of "how we can work together towards the shared goal of reducing life cycle costs by 50% by 2025 and foster the optimization of infrastructure for society." THE ASCE The American Society of Civil Engineers (ASCE) is respected worldwide for bringing to the forefront new ideas and critical concepts and technical knowledge on subjects of importance to the civil engineering professions and the public and private clients that civil engineers serve. Specialty conferences of the ASCE, such as ICSI2017, bring together, educate and inform the diverse civil engineering community, including practitioners, public and private infrastructure owners, policy makers, researchers, graduates and engineering students. The workshops, keynote lectures, panel discussions and tours broadened our understanding of research underway and best practices in the field. THE CONFERENCE The International Conference on Sustainable Infrastructure for an Uncertain World addressed what we know about an uncertain future, and probed the edges of what we do not know. Uncertainty prods engineers to go deeper, seek higher, and initiate research collaborations to assure that the best efforts can be brought together to combat the impact of climate change and energy unpredictability. THE GOALS These proceedings fulfill a primary purpose of the ICSI2017 conference: to assemble, deliver and disseminate a cogent and comprehensive assessment of he current state of sustainable infrastructure in an uncertain world. Local and global decision-making on energy policy, infrastructure maintenance, enhancement and replacement and investments in hydrology and transit were discussed and debated by experts from around the world. Those working to maintain and improve infrastructure performance in a rapidly changing operating environment face difficult and unprecedented challenges pertaining to lack of predictability, both fiscal and political. Civil engineers and allied professionals working for progressive public and private clients are able to take the long view in regards to the systems and public space that helps define the success of world class cities, from New © ASCE iii International Conference on Sustainable Infrastructure 2017 York to Paris, and Shenzhen to Montreal. To constructively provide infrastructure solutions to emerging needs, and responses that transcend electoral vicissitudes or geographic determinants, a broad, more long-ranging perspective becomes the cornerstone of the civil engineering profession's values and value. Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. THE SPEAKERS This conference began with an emphasis on the role of cities and metropolitan areas, with keynote speakers that included some of the most distinguished luminaries from the civil engineering academic and professional communities. They were complemented by two strong and pragmatic voices for grand visions and reinventing the possible: New York City's First Deputy Mayor Anthony Shorris and Paris Deputy Mayor Jean-Louis Missika. THE TECHNICAL SESSIONS The technical sessions address issues of methodology, technology, finance, policy and education while describing case studies, projects, research and lessons learned about sustainability, resilience and social equity. THE PUBLICATION This publication includes all papers presented by the authors in the plenaries, the technical sessions and concurrent poster sessions. The technical papers range from five to twelve pages and describe in significant detail the results and findings from both research and practice-oriented projects of broad interest to the civil engineering community. Case studies are also included. Each of the papers accepted for podium or poster presentation received a detailed review and evaluation by members of the Steering and Advisory Committees. The papers published in this proceeding are organized on 3 main areas: (1) Technology, (2) Policy, Finance, and Education, and (3) Methodology. Acknowledgments The editors of this publication, on behalf of the American Society of Civil Engineers and the ICSI2017 Steering Committee, Advisory Committee and Technical Committee, wish to acknowledge and thank all those who presented from the conference podium or at the poster session. The editors also thank those who served on the conference committees, including those at the NYC Metropolitan Chapter of the ASCE. Reviewing papers, moderating and introducing panel discussions and organizing site visits and tours are often thankless tasks which individually and collectively made this conference possible and these Proceedings a reality. © ASCE iv International Conference on Sustainable Infrastructure 2017 2017 International Conference on Sustainable Infrastructure Organizing Committee Conference Chair Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Feniosky Peña-Mora, ScD, FCIOB, NAC Technical Chair/Proceedings Editor Lucio Soibelman, PhD Sponsorship Chair Paul Zofnass Local Organizing Committee Chair Art Alzamora Conference Steering Committee Feniosky Peña-Mora (Chair), Rick Bell, Lucio Soibelman, John Crittenden, Bill Wallace, Doug Sereno, Michel Khouday, Katherine Sierra, Elizabeth Ruedas Conference Advisory Committee Stephen Ayres, Rick Chandler, Kathryn Garcia, Lorraine Grillo, Hank Hatch, Michael Horodniceanu, Bryan Jones, Benjamin Prosky, Vincent Sapienza, Mitchell Silver, Ponisseril Somasondaran, James Starace, Maria Torres-Springer, Polly Trottenberg , Vilas Mujumdar, Richard Anderson Conference Technical Committee Lucio Soibelman (Chair), Samuel Ariaratnam, David Ashley, Patrick Askew, Gina Bocra, Mikhail Chester, Glen Daigger, Cliff Davidson, John DeFlorio, Reginald DesRoches, Christine Flaherty, Jack Fritz, Theresa Harrison, Dan Hoornweg, Arpad Horvath, Beatrice Hunt, Chris Hendrickson, Marie Jean-Louis, Bill Kelly, John Lazzara, Angela Licata, Ray Palmares, Rosa Rijos, Encer Shaffer, Gina Bocra, Marie Jean-Louis, Mikhail Chester, Thewodros Geberemariam © ASCE v International Conference on Sustainable Infrastructure 2017 Contents Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. A Case Study and Recommendation for Large Scale Floating Wetlands ............. 1 M. McCarty, J. Ceci, and C. Streb A Novel Method for Laying Sustainable Separate Sewer Systems ...................... 13 Alaa Abbas, Felicite Ruddock, Rafid Alkhaddar, Glynn Rothwell, and Robert Andoh A Practical Engineering Approach to Interpreting Measurement Data in Uncertain Contexts...................................................................................... 26 Ian F. C. Smith and Sai G. S. Pai A Sustainable Foundation for Doyle Drive IJKL Outfall, San Francisco, CA .................................................................................................... 39 Mahmood Momenzadeh and Tim Pokrywka A Systems Approach to Water Infrastructure Planning in Urban Watersheds .................................................................................................... 53 Mark R. Norton Accounting for the Co-Benefits of Green Infrastructure ...................................... 65 Matthew Jones, John McLaughlin, and Sandeep Mehrotra Adaptive Risk Management for Future Climate/Weather Extremes .................. 76 Bilal M. Ayyub, Richard N. Wright, Ana P. Barros, J. Rolf Olsen, Ted S. Vinson, and Daniel Walker An Assessment of Benefits of Using BIM on an Infrastructure Project .............. 88 Bimal Kumar, Hubo Cai, and Makarand Hastak An Information System for Real-Time Critical Infrastructure Damage Assessment Based on Crowdsourcing Method: A Case Study in Fort McMurray ......................................................................................................... 96 Yuan Faxi, Liu Rui, and Mejri Ouejdane Application of Corrosion Potential as a Tool to Assess Sustainability of Indigenous Concrete Mixes in Bangladesh .................. 104 T. Manzur, B. Baten, Md. J. Hasan, and B. Bose Behavior of Sustainable Prefabricated Bamboo Reinforced Wall Panels under Concentrated Load .......................................................................... 116 Vishal Puri and Pradipta Chakrabortty © ASCE vi International Conference on Sustainable Infrastructure 2017 Building Smart and Accessible Transportation Hubs with Internet of Things, Big Data Analytics, and Affective Computing .................... 126 Jie Gong, Cecilia Feeley, Hao Tang, Greg Olmschenk, Vishnu Nair, Zixiang Zhou, Yi Yu, Ken Yamamoto, and Zhigang Zhu Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Case Study: Canal de Navarra Irrigation Infrastructure Sustainability; A Balanced Economic, Social and Environmental Assessment at Regional Scale ......................................................................................................... 139 Jose E. Arizón, Jose A. Alfaro, and David Fernández-Ordóñez Comparison of Resilient Modulus of Unbound Layers Obtained from Clegg Hammer and Laboratory Test .................................................................... 152 Md. Mehedi Hasan and Rafiqul A. Tarefder Decentralized Urban Composting ......................................................................... 162 Leah Retherford, Gregory P. McCarron, and Marguerite Manela Delivering Safe, Cost-Effective, Sustainable Civil Infrastructure Projects under Conditions of Non-Stationarity ................................................... 171 Bill Wallace, Dave Ellison, and Ryan Daugherty Design, Simulation, and Assessment of BIPV: A Student Accommodation Building in Australia .............................................................................................. 187 Rebecca J. Yang and Andrew Carre Evaluation of Rutting and Stripping Potential of WMA with Different Additives .................................................................................................................. 201 Biswajit K. Bairgi, Ivan A. Syed, and Rafiqul A. Tarefder Experimental Studies on Effects of Steel Studs in Composite Slabs .................. 213 S. K. Eshwari, G. J. Chandrashekar, Ahamed Maaz, N. Mohith, T. N. Manjunath, and T. Raghavendra Hydraulic Performance of Pervious Concrete Systems: Eastern Washington .............................................................................................................. 225 Liv Haselbach and Brandon Werner Identifying and Addressing Gaps for Resilient Infrastructure: A Case of Combined Stormwater Systems ........................................................... 234 Jyoti Kumari Upadhyaya, Mirandi McDonald, Nihar Biswas, and Edwin K. L. Tam New Standards for Infrastructure Delivery: California High-Speed Rail ........ 247 Margaret Cederoth, Melissa DuMond, Julie Sinistore, and Annika Ragsdale Numerical Modeling of Early Bio-Contamination in a Water Distribution System and Comparison with Laboratory Experiments .................................... 258 S. Tinelli and I. Juran NYC DEP Green Infrastructure Research and Development Project: Monitoring Strategy and Protocols ....................................................................... 270 John McLaughlin, Miki Urisaka, Franco Montalto, Fernando Pasquel, and Valentina Paiva Acosta © ASCE vii International Conference on Sustainable Infrastructure 2017 Performance Evaluation of Retrofitted Low Impact Development Practices in Urban Environments: A Case Study from London, U.K. .............. 282 Mohamad El Hattab, Dejan Vernon, and Ana Mijic Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Promoting Environmentally Sustainable Infrastructure Construction in Latin America and Caribbean ............................................................................... 295 Robert H. Montgomery and Francesc Beni Risk Assessment for Early Water Leak Detection............................................... 306 Wilmer P. Cantos, Ilan Juran, and Silvia Tinelli Refinements of GI Models in New York City Based on Post-Construction Monitoring Data to Estimate GI Performance Citywide .................................... 319 Pinar Balci, Margot Walker, Jerry Kleyman, Sri Rangarajan, and Sarah Teevan Significance of Scale in Spatial Dependencies of Urban Human Mobility and Energy Use: A Decision-Making Perspective ............................................... 328 Neda Mohammadi and John E. Taylor Spatial and Geographic Patterns of Building Energy Performance: A Cross-City Comparative Analysis of Large-Scale Data .................................. 336 Sokratis Papadopoulos, Bartosz Bonczak, and Constantine E. Kontokosta Resilience of Road Infrastructure in Response to Extreme Weather Events ....................................................................................................................... 349 Yvainne B. Valenzuela, Raphael S. Rosas, Mehran Mazari, Mark Risse, and Tonatiuh Rodriguez-Nikl Sustainable Pre-Stressed Concrete from Seawater ............................................. 361 Dan Millison and Scott Countryman Time Domain Reflectometry (TDR) Sensor for Detecting Groundwater Contamination......................................................................................................... 373 M. Hashim Pashtun and Shad Sargand Thermal Performance of Autoclaved Aerated Concrete (AAC) and (CMU) Beams Strengthened with Inorganic Basalt Composites .................................... 384 Alaa Abd Ali, Husam Najm, and P. N. Balaguru Ultra High Performance Concrete-Sustainable Solution for the Next Generation Infrastructure ..................................................................................... 397 Harshith Gowda and B. B. Das Using Big Data and Cutting Edge Tools to Optimize the Sustainability of Linear Buried Water Assets...................................................... 406 A. Vanrenterghem and P. Kraft © ASCE viii International Conference on Sustainable Infrastructure 2017 A Case Study and Recommendation for Large Scale Floating Wetlands M. McCarty, P.E., S.E., M.ASCE1; J. Ceci2; and C. Streb, P.E.3 1 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Senior Project Manager, McLaren Engineering, 100 Snake Hill Rd., West Nyack, NY 10994. E-mail: [email protected] 2 Director of Landscape Architecture Studio, Ayers Saint Gross, 1040 Hull St., Suite 100, Baltimore, MD 21230. E-mail: [email protected] 3 Bioworks Practice Leader, Biohabitats, Inc., 2081 Clipper Park Rd., Baltimore, MD 21211. E-mail: [email protected] Abstract The urban waterfronts in the United States are largely characterized by hard shoreline walls of steel, concrete, timber, and stone. Though this construction maximizes area of usable property, it impairs natural ecosystems and further separates urban communities from the natural environment. On behalf of the National Aquarium (USA), and in collaboration with other design consultants, the authors are working to transform the highly urbanized canal between two piers in Baltimore, Maryland into a floating wetlands habitat. When complete, the installation will be the first floating wetlands system of this scale in the United States. The 15,000 square foot floating wetland will provide habitat for numerous native species including crabs, mussels, wading birds waterfowl, eels, and other fish species, while allowing visitors a unique perspective of the salt marsh habitat of the Chesapeake Bay. Though small-scale floating wetlands have been installed in the Baltimore harbor in the past, their maintenance and short service lives have been hindrances to their widespread use. This floating wetland design facilitates maintenance activities and extends the service life of the wetland indefinitely through use of inert plastic materials and an adjustable buoyancy system to counteract the accumulation of marine growth. This design solution blurs the boundaries between natural and structured urban environments, showing they can coexist and flourish together. INTRODUCTION The National Aquarium is in the process of reinventing the area surrounding its main waterfront campus, located at the Inner Harbor in downtown Baltimore, Maryland. The aquarium’s waterfront campus, which helped lead the urban renewal of the Inner Harbor in the early 1980s, is now over 35 years old. The reinvention of the area around the aquarium will create a free, accessible, environmental public space, developed in partnership with Baltimore city organizations. The central tenet of the project is to encourage community engagement with the environment, build a vision of a sustainable future, and inspire conservation action, as well as potentially building a model for other urban waterfronts in the United States to follow. A centerpiece of the reinvention project is a large, 15,000 square feet, floating wetland and floating visitor platform as shown in Figure 1. © ASCE 1 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. International Conference on Sustainable Infrastructure 2017 Figure 1 – Aerial Project Rendering – Courtesy of ASG The project’s design, led by Ayers Saint Gross (ASG) and supported by McLaren Engineering Group, Biohabitats, and Kovacs Whitney & Associates, will transform the highly-urbanized canal between Piers 3 and 4 into a floating wetlands habitat. Beyond the aesthetic and educational platform the system will support, floating wetlands are expected to enhance the ecological function of the canal by providing valuable habitat, food and refuge for native species of crabs, mussels, wading birds, waterfowl, eels, and other fish species, while allowing visitors a unique perspective of the salt marshes of the Chesapeake Bay watershed. The proposed system will yield improvements to the ecosystem services supported by the site, including increasing biodiversity, nutrient cycling, attenuating wave energy, reducing the incidence or severity of low dissolved oxygen events, and providing cultural, educational and recreational opportunities. Recreating functional salt marsh habitat in an urban setting provides an educational opportunity for exposure to a much larger audience than those currently visiting natural salt marshes. “Bringing the salt marsh to the city” will allow large numbers of people to experience and learn about this vital habitat and the critical role it plays in the health of the Chesapeake Bay’s ecosystem. When complete in 2019, the installation will be the first floating wetlands system of this scale in the United States. The project is currently in the final stages of design and entering a oneyear prototype phase prior to full scale construction. REVIEW OF FLOATING WETLANDS Floating wetlands are constructed buoyant planting mediums which use the concept of biomimicry to mirror the beneficial processes of natural wetlands. Typical designs for small scale floating wetlands involve porous growing media, either plastic or © ASCE 2 International Conference on Sustainable Infrastructure 2017 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. natural, injected with closed cell foam for buoyancy, or growing media supported around the perimeter or below by air-filled polyvinyl chloride (PVC) pontoons or recycled plastic bottles. A number of manufacturers offer preassembled small floating wetland islands falling in these categories. Baltimore's Inner Harbor offers an ideal place to use these islands, as the entire shoreline has been converted to manmade structures, with very limited opportunities to restore a natural shoreline. The Baltimore Inner Harbor is home to at least three floating wetland installations since 2009, due in part to the efforts of the National Aquarium, the Waterfront Partnership of Baltimore, and Biohabitats. The National Aquarium is already familiar with floating wetland technology. In 2010, the Aquarium assembled, planted, and launched its first floating wetland island in the Inner Harbor. Since installation, the Aquarium has monitored the 200 square foot island's plant species and animal colonization, performed nutrient uptake experiments, managed the island’s vegetation, removed invasive plant species and serviced the island’s mooring. The Aquarium’s existing wetland is shown in Figure 2. Figure 2 – Photo of Existing National Aquarium Floating Wetland Island – Courtesy of McLaren Engineering One of the most significant lessons learned from the first small floating wetland island is that the wetlands tend to accumulate marine growth (fouling) over time. Though the marine growth is beneficial and desired from an environmental standpoint, the accumulated weight eventually overcomes the wetland’s buoyancy and sinks the island. Other implications are that the wetland must be easily accessible by maintenance personnel for maintaining plants and collection of washed-up litter. © ASCE 3 International Conference on Sustainable Infrastructure 2017 The flexible mooring system of synthetic rope tethered to mushroom anchors was also found to be maintenance prone in part due to the harbor’s very soft bottom, and any larger scale island would need to have a more robust and durable anchorage system to hold it in position. Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. PROJECT DESCRIPTION The floating wetland project is only phase one of the master plan to reinvent the waterfront campus. Though the floating wetland is the most distinguished feature of phase one, the phase will also include updates to transform a large fountain on Pier 4 into a freshwater marsh, new landscaping and plantings, as well as new coordinated schemes of benches, lighting, and signage to improve the visitor’s visual experience and wayfinding. The layout of the wetland contains actually three separate islands: the main central wetland island, a long, slender island to the north, and a crescent shaped section to the east, which surrounds the eastern half of the Visitor Dock. The main floating wetland island is over 250 feet long and 80 feet across at its widest. The serpentine shape of the wetlands and the channels were chosen to mimic the gentle “S” curves of a natural tidal wetland marsh. The floating wetland system will be layered; native salt marsh plants will be grown on a mesh of polyethylene (plastic) fibers. The growing medium will be supported by structural framing and dynamic pontoon buoyancy systems. Airlift pipes provide constant water flow to the topside’s shallow channels create running streams atop that run through the wetland similar to the shallow channel microhabitats found in natural tidal salt marsh habitat. An additional aeration system located under and around the perimeter of the floating wetland will constantly mix, destratify, and increase the dissolved oxygen levels in the upper six feet while improving water quality by increasing dissolved oxygen levels and destratification of the water column below. A floating Visitor Dock extends out into the wetland and is accessed by a pair of Americans with Disabilities Act (ADA) accessible gangways extending out from Pier 4. The Visitor Dock allows the public an up-close look and an immersive experience into wetland habitat. Though the wetlands and Visitor Dock had to be kept as two independent structures, architectural and flotation details give the appearance that the two are joined, providing for a more immersive experience, as shown in Figure 3. © ASCE 4 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. International Conference on Sustainable Infrastructure 2017 Figure 3 – Rendering of Floating Wetland and Visitor Dock – Courtesy of ASG WETLAND SYSTEMS Aerators and Airlifts A system of aerators will be positioned within and surrounding the wetland. The aerators force compressed air down into the water column via pneumatic hoses, air stones, and air diffusers, and let it bubble back to the surface. The aeration is targeted to improve the dissolved oxygen levels within the water in the slip and to constantly mix the upper two meters of the water column. Fish kills resulting from low dissolved oxygen, created by a reoccurring cycle of harmful algal blooms, commonly occur on an annual basis in the Inner Harbor. The often stagnate, nutrient rich surface waters of the slip create the ideal environmental conditions for an algal bloom to occur. This new aeration system, aims to prevent algal blooms from occurring by constantly mixing the upper two meters of the water column and eliminating stagnate surface water, idea for rapid growth and population explosions of several planktonic algae species. A system of air lift pipes will be located within the wetlands and provide moving, oxygenated water to small pools and shallow channels located on the topside of the floating wetland. Primarily intended to prevent stagnation of water within the wetland, these airlifts have the added beneficial effects of promoting circulation of water through and around the wetland which increases its ability to reduce the harmful overabundance of nutrients in the surrounding water. The circulation of cooler water from two meters below the floating wetland helps to moderate the temperature of the shallow channel water in summer and boost dissolve oxygen levels. These shallow channels provide refuge, feeding and spawning habitat for small fish species, juvenile fish and molting crabs. This vital microhabitat is currently non-existent in the urban waters of the slip. © ASCE 5 International Conference on Sustainable Infrastructure 2017 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Growing Medium The top surface of the wetland is constructed with unwoven polyethylene terephthalate (PET) growing media. The media, made from adhered strands of plastic, resembles a stiff scouring pad. The PET comes in sheets and are stacked together in layers to create 1 ½ to 18 inches of total thickness to achieve the desired terrain contours and marsh microhabitats, as shown in Figure 4. Locations of 1 ½ inches of media correspond to the bottom of wetland shallow wetland channels, while 18 inches occurs at areas of high marsh. Changes in contour elevations are accomplished by removing layers of PET sheets, giving the appearance of stepped contours until the vegetation develops enough to cover the media. Holes are cored vertically through the PET at regular intervals and plantings inserted. The PET sheets are laminated together and mechanically attached to the structure below via threaded rods. The highest wetland contours only extend 6 inches above the water level. The growing medium drains of water quickly and is not capable of providing capillary action to carry water upwards. Therefore, planting pocket bottoms must be located low enough that the roots can easily extend down below the waterline to provide root contact with water. Contact with the nutrient rich slip water typically results in rapid plant growth and root spread throughout the PET material. Unfortunately, floating litter in the harbor is a common problem and its removal a significant source of maintenance costs. The edges of the wetland are contoured steeply to prevent trash from beaching on the edges. The outlets of the wetland streams will be temporarily screened with a wire mesh fence, which may become permanent depending on prototype trash accumulation levels. Following initial installation of the wetland, the mesh fence is primarily intended to keep waterfowl off the wetland while the plantings mature, spread and get well established. Otherwise, waterfowl have a tendency to pluck out the plantings to create open, non- vegetated areas of roosting habitat. Figure 4 – Section through Wetland Growing Media and Structure – Courtesy of Biohabitats Dynamic Flotation System The flotation challenges of the project are numerous. The first two hurdles encountered by the design team was the very low freeboard required by the plantings. The highest marsh levels only extend 6 inches above water. Furthermore, the PET material is incredibly porous and almost entirely void space. Floating structures gain © ASCE 6 International Conference on Sustainable Infrastructure 2017 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. their stability from freeboard, which is the distance of the edge above the waterline and represents the amount of additional buoyant restorative force that can resist overturning or sinking forces. The low levels of stability constraining the design required that the wetlands be structurally integral (i.e., no joints) to the greatest extent possible. Hydrostatic and stability analyses were performed using naval architecture design software Orca3D as well as non-linear finite element analysis in SAP2000 software. The large plan area of the main wetland, engaged correctly, compensates for the design’s low freeboard. For the smaller wetland islands to the north and east, design personnel loads had to be limited to a 400 lbs concentrated load, simulating two maintenance workers only, to prevent swamping of the islands. A lesson learned from the National Aquarium’s and the design team’s previous experience with small scale floating wetlands is that the weight of marine growth accumulates overtime and will eventually sink a conventional floating wetland. However, the large scale floating wetland is a major, long-term investment and required to have a minimum service life of 30 years with minimal maintenance. The most prudent and cost-effective solution was determined to be adding a controllable ballast system to the wetland to counteract the effects of added marine growth weight. Sufficient additional static buoyancy could not be added to the design to compensate for the marine growth weight without violating the low freeboard requirements dictated by the plantings. Utilizing inflatable airbags or regularly depositing additional foam buoyancy elements under the wetland via divers was considered but eventually ruled out due to concerns with longevity and practicality. By calculating the rates of sinking of the small scale floating wetland installations already present in the harbor, the design team arrived at an estimated fouling load of 1.5 pounds per square foot per year. This rate was conservatively extrapolated 10 years out, resulting in a total design fouling weight of 15 pounds per square foot. The team anticipates that the actual rate of fouling will be initially high and then gradually taper off to near zero before year 10. The design controllable ballast system utilizes high density polyethylene (HDPE) 30 inch diameter pontoons with adjustable water fill, referred to as the “dynamic buoyancy” system. Figure 5 shows the layout of HDPE pontoons. In the unlikely event that the actual weight of fouling exceeds the design team’s predictions, the floating wetland structure is designed to easily accommodate additional pontoons being floated under the wetland, attached, and then pumped full of air to provide supplemental buoyancy. Each pontoon will be outfitted with a pneumatic air hose at the top and ballast water hose at the bottom. The hoses are run to the perimeter of the wetland where an operator can open and close valves as necessary to push air into the pontoon or bleed air outwards, thereby controlling the water level in the pontoon and the floating elevation of the wetland. A portion of the HDPE pontoons will be filled with closed cell marine foam, and will therefore provide an unchanging buoyant force, referred to as the “static buoyancy system.” This foam fill and static buoyant force are calibrated to match the weight of the wetland’s structural components, PET, and plantings. © ASCE 7 International Conference on Sustainable Infrastructure 2017 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Reserve Flotation System The PET and plantings are the only features of the wetland which extend above the surface of the water. The PET is over 95% void space, i.e., for every cubic foot of PET submerged, only 0.05 cubic feet of water is displaced. As buoyancy is directly related to the weight of water displaced, the wetland has very little buoyancy in reserve to counteract the added weight of maintenance workers and waves. In response, at contour locations above the waterline, cavities within the PET will be filled with spray applied closed cell marine foam. This foam embedded within the PET is referred to as the “reserve buoyancy system,” and is engineered to provide the added buoyancy and stability to allow people to stand on the edge of the wetland without it swamping. The foam cavities are carefully spaced in linear strips to not interfere with plantings. As the PET colonizes with biological material overtime and void space reduces, the wetland is predicted to become more stable, and its ability to support persons and wave loads will improve. The foam cavities in the PET are attached to the wetland structure below using threaded rods with oversize washer plates spaced frequently along their length. As the foam has a natural tendency to float upwards and away from the structure below, the threaded rods are required to restrain the foam and transfer the resulting buoyant forces into the structural frame. Figure 5 – Rendering of Floating Wetland Structure and Flotation – Courtesy of McLaren Engineering Structural System Over the course of design, the structural frame evolved from a grillage of carbon steel wide flange beams with high performance coating to a system utilizing the HDPE pontoons as structural beams in the long direction and aluminum wide flange beams © ASCE 8 International Conference on Sustainable Infrastructure 2017 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. in the short direction. The original steel beams were able to accommodate higher loads from tour groups walking on the wetland. However, use of carbon steel structural members was ultimately determined to be incompatible with the required 30 year low maintenance design life of the wetland. Carbon steel is more susceptible to corrosion in marine environments compared to plastics and aluminum. Passive cathodic protection systems, i.e., replaceable sacrificial anodes, can be used to mitigate corrosion, similar to those used on steel ship hulls. However, the large surface area of steel combined with difficult underwater access made replacing these sacrificial anodes at regular intervals over the wetland’s design life cost prohibitive. In exchange for reducing tour group loading, the structure was able to be switched to the more flexible, but much more environmentally inert, HDPE and aluminum materials. The HDPE pontoons run continuously in the long direction of the wetland. The pontoons are connected at their ends with bolted flange connections at approximately 45 feet intervals. These rigid connections allow the separate pontoon segments to act as single long beams. The aluminum beams run at a 90 degree angle over top of the pontoons and are connected via bolts to a HDPE connection plate fusion welded to the pontoon pipes, as shown in Figure 6. The top structural layer consists of 2 inch thick fiberglass grating. The grating is environmentally inert, light weight, and provides easy means of fastening the PET and fiber reinforced polymer (FRP) threaded rods above to the structure. The fiberglass grating also provides a sufficiently rigid base to support laminated PET layers with foot traffic and not cause damage. The wetland is designed to accommodate FEMA 100-year flood levels, resist winds, waves, and currents from a 100-year storm, locally support 40 pounds per square foot of personnel loading, and be able to withstand the catastrophic loss a pontoon’s buoyancy without structural failure. © ASCE 9 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. International Conference on Sustainable Infrastructure 2017 Figure 6 - Isometric Section through Floating Wetland Structure and Flotation – Courtesy of McLaren Engineering PROTOTYPING Prior to construction of the full-scale wetland, a one year prototyping phase is being undertaken, starting in Spring 2017. Construction and testing of the prototype will help reduce the risks inherent with designing and building a first of its kind floating wetland system. The prototype is intended to allow the project team to determine best detailing practices and operational limitations of the floating wetland before making large construction investments. The prototype design is 15 feet by 20 feet in plan and anchors to two sets of existing guide pipe piles previously used for a water taxi landing, as shown in Figures 7 and 8. On this limited footprint, nearly all of the construction details to be used on the fullscale 15,000 square feet wetland will be tested. Full scale construction will follow the prototype phase and is scheduled to begin in 2018 and finish in early 2019. © ASCE 10 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. International Conference on Sustainable Infrastructure 2017 Figure 7 – Prototype Plan Showing Terrain Contours – Courtesy of ASG Figure 8 – Prototype Section – Courtesy of McLaren Engineering CONCLUSIONS & RECOMMENDATIONS Floating wetlands are an innovative way of re-introducing natural wetland ecosystems into dense urban waterfronts. Floating wetlands have recently seen © ASCE 11