Town staff is ready to move on a project to upgrade the water circulation system in Fountain Lake, but more expensive water storage and power control projects will have to wait for now.

Town Manager Grady Miller told the council at the conclusion of a special meeting Sept. 1, that the budget includes funds for upgrades and expansions to the in lake circulation equipment. That amount is about $200,000.

The council did not vote on a motion to move forward, but will vote on design and construction contracts as the project moves ahead.

Dr. Rick Amalfi, a water quality consultant the town uses for advice regarding the lake issues explained, as he has before, that the lake is a closed system that has high concentrations of nitrogen and phosphorus creating an excellent growing climate for algae.

The results of those conditions are odor issues and occasional fish kill incidents with the lake.

Amalfi said that the nitrogen and phosphorus are nearly impossible to filter out of the water, and there is additional contamination with irrigation runoff with fertilizers.

Community Services Director Mark Mayer told the council that in the past staff has had reasonable success with chemical treatment and the existing circulation. However, this summer, for reasons he could not specify, the problems grew worse. Chemical treatment and existing circulation equipment, plus increasing Fountain run times, were unable to keep up.

Mayer said strong windy conditions in late spring and early summer kept the Fountain run times to a minimum and may have contributed to additional contamination with dust.

The plan to upgrade the circulation includes replacement of the existing 12 aerators, adding 12 more similar aerators and adding an additional 10 horizontal circulators.

Amalfi explained that the improved circulation has a number of positive aspects including an increase in oxygen, which improves the decomposition of organic substances such as algae; it also prevents the formation of oxygen-poor cold spots in the lake that result in fish dying; it prevents the formation of toxic gases such as ammonia and sulfides; it prevents algae blooms and increases oxidation.

Amalfi said the circulation upgrades, plus chemical treatments and even the possibility of using dye to screen out UV rays, could significantly improve the quality of water, even for use in irrigation.

Mayor Linda Kavanagh asked Amalfi whether mosquito growth on the lake is a concern. He said the improved circulation should all but eliminate that, but he also added that the lake is large enough that even the air currents move the water enough to keep mosquitos away.

Control systems

With circulation a critical aspect of water quality the operation of the Fountain plays and important role and the discussion continued with information about upgrading the pumping and power controls for the Fountain.

The council was told by Patrick Keller, with Keller Electric, that the existing system is operating with 1970s technology and is not even compliant with new codes. He said it is showing its age and will need to eventually be replaced.

His estimate to replace the controls is about $700,000.

A new system with a processed controller would provide more flexibility regarding power use and Fountain display. It could also be remotely operated and would provide information on power use and weather conditions in real time.

The controller would provide variable frequency drive to the pumps which would greatly reduce power costs. Currently the pumps operate at full power or they are off with no options for variable speed in between.

Water storage

The Council also heard information about creating a storage facility for irrigation water. This would provide better quality water for irrigation and improved turf in the park. However, at the same time, separate storage would increase the standing time of the water in the lake, which is currently used for irrigation, potentially aggravating the water quality issues.

Coates Irrigation of Gilbert made a presentation on options for water storage. They stated that one option that had been discussed at length, a dike separating the irrigation water from the rest of the lake, is not feasible due to the amount of water needing to be stored.

An above ground steel storage tank that could be built within the confines of the pump house compound at the park would need to be about 77 feet in diameter and 24 feet high. It would cost just shy of $1 million.

An underground concrete storage area would need to be more than 70 feet square and 25 feet deep. That would cost about $1.3 million, according to Coates.

A third option of burying 16 interconnected fiberglass tanks would cost an estimated $1.1 million.

Miller said financing options for the water storage and controller upgrades would require further study and discussion. He added that he would have staff move forward on the lake water aeration improvements since the money is in the current budget.