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Council orders review of water/wastewater master plans after consultant flags modeling and capacity issues
Summary
Consultant Dave Stewart told council he found calculation errors and omissions in the city’s water and wastewater master‑plan work and recommended the city recover and reuse a 2015 WaterCAD model and run a focused technical review. Council directed the city manager to convene experts and report back within weeks.
Counsel and staff moved quickly after a technical presentation from consultant Dave Stewart, who told the Lago Vista City Council that portions of the city’s water and wastewater master plans contain calculation errors, missing modeling artifacts and capacity assumptions that city staff should verify.
Stewart told council that a WaterCAD hydraulic model created for the city in 2013–2015 exists and that city engineers should obtain and update it rather than re‑creating baseline data from scratch. He said key growth‑and‑capacity assumptions in the adopted master plan appeared inconsistent in several places: the per‑LUE (land use equivalent) water demand used in one calculation (50 gallons per day per LUE) appears to be a groundwater figure, while surface‑water and distribution modeling referenced a lower 20‑gallons per LUE calculation; pump sizing and the presence or absence of a hydropneumatic pump building for new tanks would change the practical service capacity, and some proposed transmission mains and large diameter installations were specified without clear documentation of the necessary on‑system transmission line work to move water from new tanks to the distribution grid.
Stewart urged the council to retrieve the existing WaterCAD model and the supporting CAD files and as‑built records from the engineering firm that prepared the work and to commission a short technical verification. He said the city’s lidar and drainage mapping would help update the model quickly, and that professional fees for an updated model would likely be less expensive and faster than recreating all data.
Council voted unanimously to direct the city manager to convene a meeting with Stewart and staff and to report back with verification notes; the motion calls for city staff to meet with Stewart within roughly three weeks to assess the claims and propose remedial steps.
Ending: Council directed the city manager to convene Stewart and staff for a technical review within weeks and return to council with findings and recommended next steps; staff will also determine what existing model assets can be recovered from prior consultants.
