Board authorizes bidding for Sweetwater Reservoir aeration and destratification project; staff estimates added usable supply

The Sweetwater Authority governing board voted unanimously April 9 to direct the general manager to issue a notice inviting bids for an aeration and destratification system at Sweetwater Reservoir.

Dr. Kim, who presented the design, said the system would introduce air via diffuser piping to vertically mix the reservoir, reduce stratification and lower algae growth. That mixing is intended to improve reservoir water quality, reduce treatment chemical needs and allow increased withdrawal from the reservoir. “With this, actually, it reduced the algae growth and it improved the water quality. Actually, that means we can have more volume that can be utilized for our production,” Dr. Kim said. The staff presentation cited an estimate that the system could increase available supply by roughly 1,790 acre-feet per year.

Staff explained permitting and schedule constraints: environmental permits are in progress with four agencies, two tentative approvals achieved and two permits expected in the first quarter of next year. The presentation noted a limited in-water construction window beginning in September to avoid bird-breeding season; staff said they were advertising for bids this fiscal year so a contractor could be ready to begin work when the window opens.

Budget: staff presented an engineer’s estimate of $2.9 million for construction and recommended a next-year construction budget of $3.3 million (staff included contingency and construction management allowances in the packet). The board approved the motion to advertise for bids; staff will return with bid results and a recommendation for award once bids are opened and evaluated.

Vote: the motion to direct the general manager to issue a notice inviting bids passed unanimously with Director Delgado absent.