
Tuesday, December 4, 2007 : 1:40 p.m.
Laboratory-Scale Modeling of Fouling of Dam Drains
Two model drain systems have been constructed and operated with circulating water to induce biofouling and mineral buildup. These systems approximate the cross-sectional scale of functioning drains. One system (the Ohio model) uses relatively coarse matrix media and has been maintained as an intermittently flowing aerobic system. The second (the Denver model) uses a more complex and finer matrix around the drain pipe. Flow rate, cross-sectional head and water quality have been recorded over the months and years of operation.
The Ohio model has experienced biofilm development, including aerobic filamentous and nonfilamentous heterotrophs, but not iron-related or sulfate-reducing microflora. Although the stock water (local well water) used has a high iron content, the predominant mineral deposited in the matrix is calcite, resembling clogs in many Reclamation dam drain systems. There has been minimal head build up due to clogging in the Ohio model, but sampling ports have clogged. The matrix also efficiently removes iron and alkalinity from water within 30 min of recharge with new stock water.
The Denver model, also stocked with local well water, has clogged more quickly, developed iron biofouling, and altered water chemistry during operation.
The model systems have demonstrated that field-type dam drain clogging phenomena and responses can be recreated at the “bench” scale, much as they have been with wells. The clogged models are now available for cleaning tests. Such models can be reproduced to resemble specific drain situations, and used to calibrate mathematical modeling of such systems.
Denise M. Hosler, Bureau of Reclamation Denise Hosler in an environmental scientist with the Environmental Applications and Research Group, Bureau of Reclamation, Denver, CO. She holds a BA in Biology and MBS in Plant Sciences from the University of Colorado. She previously worked in ground water remediation and in hazardous chemical management. Reclamation activities include ground water sample management, invasive species and integrated pest management, dam safety and clogging activities, and natural hydrology function in urban areas. In addition to biological clogging research, she is currently assisting with research on the presence and spawning patterns of Dreissena spp. found in waters of the western states.
Stuart A. Smith, M.S., CGWP, Smith-Comeskey GW Science LLC Stuart Smith has been active in the ground water industry for over 27 years, since 1996 with Ground Water Science (www.groundwaterscience.com), where he specializes in well troubleshooting, maintenance, and rehabilitation. He holds CGWP designation, and MS and BA degrees from The Ohio State University (more than a men’s football team) and Wittenberg University (ditto), respectively. Mr. Smith is the author or coauthor of numerous studies and publications on well and drain biofouling, well maintenance and rehabilitation and well construction. He is active in national and state-level water supply and ground water organizations, including NGWA’s Microbial Interest Group.