NEW-Project to Address Water Taste Concerns

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City Approve

s Phase One of Project to Address Water Taste Concerns

The City has experienced taste and odor issues in its water for many years.  This issue is caused by algae in the lake that releases geosmin, an naturally occurring molecule that contributes to the earthy taste and odor and is detectable at very low levels.  While geosmin levels are generally detectable year-round, levels historically spike in the late summer and then again during the winter.  The current treatment at the water purification plant uses an advanced filtration process that consistently meets regulatory requirements for safe drinking water.  However, it is less effective at removing the geosmin.  Although this is not a health concern, it does affect the aesthetic quality of the treated water that is distributed to our customers.

In 2017, the City hired an engineering consultant to evaluate treatment alternatives to improve the taste of our water.  At the conclusion of that study, the consultant recommended the addition of granular activated carbon (GAC), commonly used to absorb taste and odor compounds.  The City then approved a contract to design the new GAC filtration units (phase two) at the water purification plant to achieve these goals.  The design phase is currently ongoing, and construction is anticipated to begin later this year and be completed in early 2021.

Phase one includes a similar improvement, on a smaller scale, to replace filter media in the City's existing filter units with the same GAC.  The City approved construction of phase one, referred to as the GAC Trident Retrofit project, at its regular meeting on January 24th and will begin construction in March 2019.  Construction is expected to be completed by May 2019.  This intermediate improvement is part of the overall strategy and will reduce geosmin levels by approximately 20%.  The second phase, which includes construction of the GAC filter units, is projected to further reduce geosmin levels by 90% or more.  While no treatment strategy can guarantee performance, these projects should significantly improve the taste of our water.

Originally the City planned to construct these improvements during the next plant expansion that is scheduled to occur in the next 5-10 years, but the City requested the Water Utility Department to investigate options for implementing those improvements sooner due to the taste and odor events.

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