Agenda Information Sheet
DEPARTMENT: Water Production
CM/ ACM: Howard Martin
Date: August 22, 2016
SUBJECT
Title
Receive a report, hold a discussion and give staff direction regarding the "Manual for the Control, Operations and Maintenance of Zebra Mussels" for design, construction and installation of key improvements to control and monitor zebra mussels for both Lake Ray Roberts and Lake Lewisville raw water sources and supply lines.
Body
BACKGROUND
In 2015, Arcadis consulting engineers were selected to perform a study on the zebra mussel issue for both raw water sources and develop zebra mussel management approaches that balance the risk of future infestations with capital spending and potential unintended downstream consequences.
Zebra mussels have major impacts on potable water facilities by attaching to surfaces of pipes, trash rack, screens, gates, valves, pumps; constricting flows and fouling of support infrastructure. Zebra mussel infestation adversely affects the ecosystem and water quality such as decrease turbidity and increase algal and cyanobacteria growth. Increased water clarity allows for greater light penetration and may stimulate growth of blue-green algae increasing taste and odor issues and also increasing the potential for Microsystin that can produce neurotoxins in the source water.
Management, operation and maintenance approaches in the manual considered the following: source water quality including seasonal water quality changes, physical characteristics of each structures to assess the susceptibility to fouling and the potential impact of fouling, hydraulics including pipeline velocities, capacities and detention times, operational impacts including required labor hours, capital costs and O&M costs, public perception including the selection of publicly accepted technologies. Operation of downstream water treatment plants, zebra mussel biology and ecology, planned future improvements, current and future regulations and risk redu...
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