Get Full Government Meeting Transcripts, Videos, & Alerts Forever!
Get email alerts on the Plant Expansion topic
No spam. Unsubscribe anytime.
Staff outlines Hazen alternatives and wide cost range for treatment-plant expansion; board cautions pending TDEC sign-off
Summary
Hazen presented six alternatives for the treatment-plant expansion, with staff favoring conversion to plug flow or an oxidation ditch with biological phosphorus removal; estimates are planning-level (class 5) with a wide +/- range and an example Phase 1 planning cost cited at $80 million. Hazen expects to submit a TDEC permit application in about 12 months, though board members urged caution until formal approvals arrive.
Staff updated the board on alternatives analysis completed by Hazen for a planned expansion of the Stone River water-treatment facility. Speaker 2 summarized six technology pathways: oxidation ditch with chemical phosphorus removal; oxidation ditch with biological phosphorus removal; oxidation ditch plus hydrocyclones; conversion to plug flow; plug flow with densification; and a mobile organic biofilm option.
Speaker 2 said the analysis applied weighted criteria—reliability, flexibility, lifecycle cost and operational familiarity—and that the two highest-scoring alternatives were conversion to plug flow and an oxidation ditch with biological phosphorus removal. Hazen identified additional hydraulic measures (additional post aeration and submersible aerators) and potential UV or effluent adjustments to meet hydraulic goals.
Staff emphasized the planning-level nature of cost estimates: Hazen provided class 5 estimates with a wide range (roughly minus 35% to plus 65%), making the figures directional rather than definitive. Speaker 2 noted illustrative phasing options, including a Phase 1 planning number of about $80 million that would not achieve the most aggressive near-term allocation goal (the transcript cites scenarios that could defer $23 million to $40 million into later phases depending on the approach). Staff suggested phasing to buy time and reduce initial capital exposure while maximizing use of existing infrastructure.
Board members asked about the TDEC permitting timeline. Speaker 2 said Hazen expects to prepare and submit a permit application within roughly 12 months and conveyed the consultant’s confidence about eventual approval; at least one board member said the board prefers caution and will wait for signed permit documentation before assuming approval.
No formal action was taken; the update was informational and staff will continue refining phasing, costs and design details before returning with specific budgetary requests.
