The selected consultant will prepare a work plan and execute the work plan to apply aluminum sulfate and sodium aluminate to Lake Fenwick. The selected consultant shall employ staff with experience to safely and effectively implement the alum treatment. The application shall occur in October 2023 unless otherwise directed by the City Engineer. The selected consultant shall apply the aluminum sulfate and sodium aluminate only when the lake water temperature is above 5.5C (42 F) throughout the water column and only when the wind speed is less than 15 mph at the lake surface. The effective dose of aluminum to be applied to Lake Fenwick shall be 11.7 mg Al/L within the water column of the entire lake during the application. The selected consultant shall employ a treatment barge (boat) with on-board chemical storage tanks and applicator, equipped with a GPS-linked computer system for barge (boat) guidance that is integrated with real-time bathymetric measurements and provides chemical dosing control for both aluminum sulfate and sodium aluminate pumping rates based on real-time depth as well as maps/documents areas of the lake already treated. The selected consultant shall complete the application from start to finish within 2 working days, with one additional day for mobilization and another additional day for demobilization. To be awarded this project, the Proposer shall provide satisfactory evidence that his/her firm has conducted buffered, whole-lake alum treatments in a minimum of three lakes that are 50 surface acres or more in size, within the last five years. Chemical application experience on these projects shall include application of alum as the nutrient inactivation and sodium aluminate as the buffering agent. Any questions regarding this project should be directed to Rowena Valencia-Gica at (253) 856-5585 or rvalencia@kentwa.gov.
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