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Staff: 30‑inch tile is engineering response to flat grade, not new industrial demand
Summary
Residents asked whether a planned 30‑inch tile is tied to an ethanol plant; engineering staff said the upsizing addresses flat pipe grade and velocity needs so the system can achieve sufficient cover and flow, though the larger pipe could increase construction impact on fields.
At the Aug. 6 reconvened hearing, Terry Richardson asked whether the proposed 30‑inch tile was intended to accommodate an ethanol plant. Engineering staff and the surveyor’s office responded that the decision to upsize is an engineering response to watershed geometry and grade constraints rather than to industrial water use. "The tile is so flat from the ditch to where it goes up that hill in order to maintain 2 feet percent of velocity in the pipe, we had to upsize it to a 30 inch," the engineer said.
Staff explained that a 24‑inch pipe could handle capacity in places but, on the existing flat grades, would need steeper slopes and would be shallower near the outlet, reducing cover. Upsizing downstream allows crews to run a flatter grade and achieve deeper cover upstream, which can mean more excavation and temporary field disruption in some parcels.
