Cristiane Q. Surbeck

Ecological Control of Fecal Indicator Bacteria in an Urban Stream

Fecal indicator bacteria (FIB) have long been used as a marker of fecal pollution in surface waters subject to point source and non-point source discharges of treated or untreated human waste. In this paper, we set out to determine the source(s) of elevated FIB concentrations in Cucamonga Creek, a concrete-lined urban stream in southern California. Flow in the creek consists primarily of treated and disinfected wastewater effluent, mixed with relatively smaller but variable flow of runoff from the surrounding urban landscape. Dry and wet weather runoff contributes nearly 100% of FIB loading to Cucamonga Creek, while treated wastewater contributes significant loading of nutrients, including dissolved organic carbon (DOC), phosphorus, nitrate, and ammonium. FIB concentrations are strongly positively correlated with DOC concentration in runoff (Spearmans rho >or= 0.66, P <or= 0.037), and microcosm studies reveal that the survival of Escherichia coli and enterococci bacteria in runoff is strongly dependent on the concentration of both DOC and phosphorus. Below threshold concentrations of 7 and 0.07 mg/L, respectively, FIB die off exponentially (die-off rate 0.09 h(-1)). Above these thresholds, FIB either grow exponentially (growth rate 0.3 h(-1)) or exhibit a periodic steady-state in which bacterial concentrations fluctuate around some mean value. The periodic steady-state pattern is consistent with a Lotka-Volterra predator-prey oscillation model, and the clearance rate (20 microL predator(-1) h(-1)) obtained by fitting the model to our data is consistent with the hypothesis that predacious protozoa regulate FIB concentrations in runoff at high DOC concentrations. Collectively, these results indicate that FIB impairment of Cucamonga Creek is best viewed as an ecological phenomenon characterized by both bottom-up and top-down control.

Progress and Recommendations for Advancing Performance-Based Sustainable and Resilient Infrastructure Design

AbstractIncreasing variability in climate and environmental degradation call for an infrastructure design paradigm that considers both sustainability and resilience using performance-based metrics. This paper discusses recent progress in this direction, including recent and emerging infrastructure rating systems, design technologies and tools, and examples of sustainable and resilience infrastructure projects. Recommendations are made for new research, development of new technologies and tools, and policy changes needed to further advance progress towards integrating performance-based approaches across the entire design cycle. These include a call for improved models and tools to better evaluate the full suite of infrastructure costs and benefits, both internally and externally; multicriteria design to assess tradeoffs among all costs and benefits at multiple scales; and an iterative design cycle based on measurable performance criteria.

A multi-variate methodology for analyzing pre-existing lake water quality data.

Environmental agencies are given the task of monitoring water quality in rivers, lakes, and other bodies of water, for the purpose of comparing the results with regulatory standards. Monitoring follows requirements set by regulations, and data are collected in a systematic way for the intended purpose. Monitoring enables agencies to determine whether water bodies are polluted. Much effort is spent per monitoring event, resulting in hundreds of data points typically used solely for comparison with regulatory standards and then stored for little further use. This paper devises a data analysis methodology that can make use of the pre-existing datasets to extract more useful information on water quality trends, without new sample collection and analysis. In this paper, measured lake water quality data are subjected to statistical analyses including Principal Component Analysis (PCA) to deduce changes in water quality spatially and temporally over several years. It was found that the lake as a whole changed temporally by season, rather than spatially. Storm events caused the greatest shifts in water quality, though the shifts were fairly consistent across sampling stations. This methodology can be applied to similar datasets, especially with the recent emphasis by the U.S. EPA on protection of lakes as water sources. Water quality managers using these techniques may be able to lower their monitoring costs by eliminating redundant water quality parameters found in this analysis.

Girls Go Green, Girls Go Global!

Demographic data suggests that the number of students who will enroll in engineering programs at U.S. universities will decline in the near future. One way to offset the potential reduction in the number of future engineers in this country is to increase the number individuals from currently under-represented groups in STEM majors. For example, women make up more than one-half of all college students in this country but are less than one-fourth of the engineering student body. There are initiatives at all levels to increase the number of women studying engineering, and this paper describes two grass-roots level initiatives at the Missouri University of Science and Technology in Rolla, Missouri. The Missouri S&T geological engineering program and the Womens Leadership Institute teamed to develop two new programs intended to attract rising junior and senior high school women. Girls Go Green and Girls Go Global share many attributes including a focus on hands-on activities, contemplative activities, structured recreational activities, and interaction with undergraduate and graduate students who act as potential role models. Each camp includes theme-specific activities. For example, a multi-part Girls Go Green activity is the erection of a 1 kW wind turbine on a 50 ft guyed tower that requires the girls to learn basic surveying, the use of scratchpad math software (and trigonometry knowledge), and the ability to work together during the wind turbine assembly and erection. In Girls Go Global, female faculty from Brazil and Guatemala led country-specific activities such as a Guatemalan fashion show and a sing-along in Portuguese. Both programs are relatively new, but preliminary data are available that show meaningful direct and indirect yields associated with these efforts.

Social Sustainability and Important Indicators in Infrastructure

Sustainability is commonly described as the intersection of environmental, economic, and social spheres, where the intersection represents that the three spheres are in balance in a project or activity. While the environmental and economic aspects of projects are commonly addressed by engineers and scientists when working on a project, the social aspects are less quantifiable and therefore somewhat neglected. The term “social sustainability” is used to represent the social, societal, and human engagement, impact, and vulnerablities in a project. This concept is gaining attention and is being addressed by the Integrated Network for Social Sustainability (INSS), an inter-disciplinary research network funded by the National Science Foundation. As part of the many INSS activities, a web-based repository is being developed to list and evaluate many social sustainability indicator tools that currently exist. The purpose of this paper is to describe the advantages and shortcomings of several of these tools, as well as to call for the need for such an assessment for civil, environmental, and water resources infrastructure. Tools to be assessed include the social categories of the U.S. Green Building Council’s LEED system and the Institute for Sustainable Infrastructure’s Envision TM Sustainable Infrastructure Rating System. Further, social Life Cycle Assessment and the Environmental Protection Agency’s Recovery Potential Indicators for watersheds will be evaluated.

Storm Water Runoff from an Urban Watershed in Southern California: Top-Down Approach for Characterizing and Modeling Pollutant Loading Rates

In southern California, storm water runoff from urban watersheds impacts coastal water quality. At the present time, coastal water quality impairments are usually managed through the development and implementation of a total maximum daily load (TMDL) plan, for which waste load allocations (WLA) and load allocations (LA) are developed, respectively, for the primary point and non-point sources of pollution in the watershed. The WLA and LA values are developed after weighing different pollutant source management scenarios, typically with the help of a distributed model of the watershed — for example, the geographical information system (GIS) model called BASINS. Because of challenges associated with this approach, we explore an alternative paradigm for modeling pollutant flow out of large watersheds that we term top-down , as opposed to the bottom-up approach employed by distributed models described above. In this alternative approach, the emphasis is on developing scaling relationships for pollutant loading rates that apply at the scale of large sub-drainages and the watershed as a whole. These scaling relationships could, in principle, be used for engineering calculations (e.g., for the design phase of storm water treatment facilities), to assess the contribution of individual watersheds to coastal pollution, and as a benchmark against which distributed models can be compared and tested. To this end, a series of studies were carried out at three sites in the Santa Ana River watershed, a large urban watershed encompassing in southern California. From the data, fecal indicator bacteria loading rates appear to scale as a power law with volumetric flow in a manner that varies by site, but is robust within, and between, storms at a single site. The physical basis for these scaling relationships, as well as the relationship between contaminants and particles eroded during storm events, are explored and developed.

Fecal Indicator Bacteria Entrainment from Streambed to Water Column: Transport by Unsteady Flow over a Sand Bed.

Storms cause a substantial increase in the fecal indicator bacteria (FIB) concentrations in stream water as a result of FIB-laden runoff and the release of FIB from stream sediments. Previous work has emphasized the association between FIB and bed sediments finer than sand. The objectives of this work were to elucidate the effect of various velocities on the entrainment of bed-dwelling coliforms in sand-bed streams and to refine methodologies for quantifying sandy streambeds as sources of FIB. Pump-induced hydrographs were created using a stainless steel nonrecirculating flume. Experiments consisted of simulating four storm hydrographs and collecting water samples upstream and downstream of a sand bed at selected intervals. Bed sediment samples were collected before and after each event. The highest concentrations of total coliform and suspended sediments generally occurred in the downstream samples during the rising limb of the hydrographs as a result of entrainment of coliforms and sand from the bed to the water column. There was a first flush effect in the system, as the upper layer of sand was influenced by a rapidly increasing velocity at ∼0.2 m s. Coliforms downstream of the sand bed increased rapidly as velocity exceeded this threshold but then declined even as velocity and discharge continued to increase. This likely reflects the depletion of coliforms as the more densely populated sediment layer was flushed out. There is evidence that streams with sand beds harbor enough FIB that development of total maximum daily loads (TMDLs) should include consideration of them as a source.

Ultrasonic measurements of suspended sediment concentrations at Harris Bayou, Mississippi

The use of ultrasonic acoustic technology to measure the concentration of fine suspended sediments has the potential to greatly increase the temporal and spatial resolution of sediment measurements while reducing the need for personnel to be present at gauging stations during storm events. In collaboration with the USGS, a customized field deployable system was installed to monitor fine sediment particles, less than 100 micron in diameter, in suspension at Harris Bayou near Alligator, MS. Calibration measurements show good agreement between laboratory grade equipment and the new prototype system. The field unit consists of two immersion ultrasonic transducers measuring attenuation of 20 MHz acoustic signals propagated through suspended particles. The results of field prototype will be presented here.

Engaging International Perspectives through EWRI for a Global Profession

The diverse range of global water and environmental issues must be acknowledged to deal effectively with the challenges facing their management in the decades ahead (McDonald et al. 2011; Postel 2010). Nationalistic attitudes are giving way to international collaborations to resolve such problems. These issues require productive interaction among professionals in different parts of the world to most efficiently share approaches and collaborate on innovative developments. One role that professional societies can play is providing opportunities for such collaboration through their activities, including conferences. However, due to imbalances in income and resources in different countries, it can be difficult for colleagues in developing countries to attend meetings in more developed countries. The Environmental and Water Resources Institute (EWRI) of ASCE has been increasing international collaboration in global issues, such as water availability, climate change, and pollution control, by partially supporting competitively selected international fellows from developing countries through the Visiting International Fellowship (VIF) program to attend EWRI’s annual World Environmental and Water Resources Congress. Since the program was established, it has successfully increased participation of water resources and environmental professionals from developing countries in EWRI conferences and promoted sustained professional and cultural exchange. Since 2001, 30 fellowships have been awarded to professionals and students from 19 different countries. One of the reasons for the program’s success is that each fellow has a United Statesor Canada-based host who is an ASCE or EWRI member who often shares common research and professional interests. The VIF program focuses on the annual EWRI congress, where fellows give technical presentations in sessions specific to their area of expertise, providing the best possible opportunity for technical exchange and networking with their global peers. To take advantage of the range of global perspectives represented by the fellows as an educational opportunity for the EWRI community, each year the fellows have been featured in a panel discussion to compare their countries’ water issues. All fellows also participate in networking and intellectual exchange outside of the congress through seminars, meetings, other professional visits, and cultural tours, often arranged by their hosts, to promote sustained professional and cultural exchange. Through these activities the fellow and host explore opportunities for joint collaboration with appropriate partners, including research projects, coauthored papers or books, or extended visits in either country. The program requires some specific activities at the EWRI congress but otherwise offers flexibility to tailor an itinerary that serves the interests of the fellow. In preparation for the 10-year anniversary of the VIF program, the VIF committee administered a survey of past fellows and hosts to learn how the experience affected them professionally, whether they continued to collaborate, and whether they returned to additional ASCE events. After 12 weeks, survey responses were retrieved from 72% of fellows and 46% of hosts contacted. The results of the survey help assess the success of the VIF program. Almost 20% of fellows reported attending EWRI congresses beyond the one initially attended. This is substantial, given the expenses involved in attending such conferences for participants from developing countries. Survey results also indicated that the program’s other major objective of promoting sustained cultural and professional exchange is being met. Most past fellows and hosts remain in contact by exchanging information about projects or activities being developed in their organizations, maintaining contact for collaboration on publications, visiting each other’s countries since the fellowship, and becoming close friends with people met during the fellowship. The feedback from the fellows and hosts regarding their experiences with the program has been overwhelmingly positive. A few highlights from the survey responses regarding international collaborations follow: • Academic and career growth after receiving the fellowship. Most of the fellows reported publishing numerous research articles, receiving invitations to present at conferences, and receiving awards due to collaborations strengthened by the fellowship. One of the fellows is now a member of parliament in her country, influencing decisions made for managing water, health, and the environment. Another fellow noted that the fellowship provided a very positive introduction for him to a new president at his university shortly after he received the fellowship. One fellow was awarded a fellowship from the United Nations Industrial Development Organization to participate in a group of experts regarding water supply in postcrisis situations. Another fellow noted that the visits during his fellowship solidified his decision to focus his career on urban water supply management. Several of the fellows mentioned having been promoted at their institutions since receiving the fellowship. • Collaborations within ASCE/EWRI. Several of the fellows joined EWRI committees after attending the congress with the fellowship, and three of the fellows indicated they had attended other EWRI congresses after receiving the fellowship.

Response to Comment on “Coastal Water Quality Impact of Stormwater Runoff from an Urban Watershed in Southern California”

Field studies were conducted to assess the coastal water quality impact of stormwater runoff from the Santa Ana River, which drains a large urban watershed located in southern California. Stormwater runoff from the river leads to very poor surf zone water quality, with fecal indicator bacteria concentrations exceeding California ocean bathing water standards by up to 500%. However, cross-shore currents (e.g., rip cells) dilute contaminated surf zone water with cleaner water from offshore, such that surf zone contamination is generally confined to < 5 km around the river outlet. Offshore of the surf zone, stormwater runoff ejected from the mouth of the river spreads out over a very large area, in some cases exceeding 100 km2 on the basis of satellite observations. Fecal indicator bacteria concentrations in these large stormwater plumes generally do not exceed California ocean bathing water standards, even in cases where offshore samples test positive for human pathogenic viruses (human adenoviruses and enteroviruses) and fecal indicator viruses (F+ coliphage). Multiple lines of evidence indicate that bacteria and viruses in the offshore stormwater plumes are either associated with relatively small particles (< 53 microm) or not particle-associated. Collectively, these results demonstrate that stormwater runoff from the Santa Ana River negatively impacts coastal water quality, both in the surf zone and offshore. However, the extent of this impact, and its human health significance, is influenced by numerous factors, including prevailing ocean currents, within-plume processing of particles and pathogens, and the timing, magnitude, and nature of runoff discharged from river outlets over the course of a storm.