Committee hears Sabey pledge of 'dry‑first' cooling; sewer permits and sampling required
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Summary
Sabey told staff its design is 'dry‑first' and uses adiabatic misting only above ~80°F; Butte‑Silver Bow pretreatment staff said industrial wastewater would require permits, separation of sanitary and industrial lines, and regular sampling — details on chemical composition and off‑site treatment remain outstanding.
The Sabey data‑center team and county staff told an ad hoc committee that the project’s cooling concept is designed to minimize water and wastewater impacts, but that firm permitting, sampling and off‑site treatment plans are required before any industrial discharge would be allowed.
Bob Morris read a statement submitted by Sabey that described a closed‑loop liquid cooling system for IT equipment, dry air heat exchangers and adiabatic misting enabled only above about 80°F. The statement said the project includes "a covered thermal storage" to buffer loads and reuse brief adiabatic drawdown; it also said routine adiabatic drains and any intermittent purge/blowdown are to be captured, monitored and managed rather than discharged uncontrolled.
County pretreatment coordinator Eric Onder told the committee: "We do have limits and levels on discharge... they would have to separate their sanitary line from their industrial line ... we would require regular ... sampling." Onder said industrial waste cannot be discharged without a permit and that the metro sewer program requires sampling to be sent to accredited labs for compliance verification. He also noted that typical vendor cleaning cycles for cooling equipment are often once or twice a year and that collected cleaning water is commonly sent to a chemical treatment facility rather than discharged directly.
What remains unresolved: Committee members asked Sabey whether any solvents/chemicals would be used during cleaning and where blowdown or maintenance waters would go. Sabey (remote) said vendor specifics were not finalized and that collected maintenance water would be routed to an off‑site chemical treatment facility when applicable; committee members asked staff to obtain vendor engineering and handling plans for the record.
Why it matters: separation of sanitary and industrial flows, required sampling and permit constraints define whether any water leaving the facility is treated to county standards and whether routine operational discharges could occur. The pretreatment rules and the county ordinance on discharge/exceedances (noted by staff) set the regulatory framework for approvals.
Next steps: the committee tasked staff to request detailed vendor engineering, cleaning protocols and any third‑party treatment arrangements from Sabey and to have metro sewer staff outline permitting steps for prospective county reviewers.
