Preston resident Thane Corbridge addressed the City Council during the public-comment portion of the meeting to raise long-running concerns about groundwater, stormwater infrastructure and a 30-by-30-foot landslide that he says occurred in September 2023 along the east edge of his property.

Corbridge said his family has lived on the site for decades and that groundwater in the area has historically been high. He told the council he had taken measurements and drilled monitoring holes following the 2023 slide; he reported finding groundwater as much as 44 inches below the surface in one hole the following spring. Corbridge said pressure irrigation, removal of open canals, and new subdivision drainage had changed how water moves across the plateau and that groundwater appears to be channeling in unexpected ways.

Corbridge said he had discussed the issue with city staff and with developers and that he had submitted photographs and a written packet to the council. He described an installed surface drain pipe along Fourth that he said sometimes discharged water and at other times did not; he said water was observed escaping around the pipe’s gravel bedding. Corbridge said some grates were not sited at the low spot in nearby fields, causing surface water to pond and percolate into the ground.

Council members and staff asked detailed questions about location, how water flows across the area and whether irrigation practices, pressurized irrigation and removal of open ditches contributed to subsurface saturation. Councilors noted historical slides in other parts of the hollow and asked whether Corbridge had discussed the matter with the state Department of Environmental Quality (DEQ). Corbridge said he had been told (by a third party who contacted DEQ) that DEQ considers groundwater issues to be the local municipality’s responsibility; Corbridge said he had no direct DEQ documents to present to the council.

Councilors asked Corbridge to point to specific features on his packet’s maps. He indicated an easement in the southwest corner of his parcel that his family says was intended to convey water away from the field. He suggested that different road and subdivision alignments could have reduced the volume of surface run-off and that if the neighboring subdivisions had connected to an existing storm drain instead of relying on swales and retention, some of the current problems might have been mitigated.

Council members said they appreciated Corbridge’s work gathering photos and drilling holes to measure groundwater. Several councilors also said that detailed groundwater mapping and forensic engineering would be expensive and that the city’s engineers reviewed developers’ stormwater studies for other subdivisions and found them acceptable. Councilors discussed whether additional drainage or road realignment would be feasible and whether retention-pond sizing might be altered on future plats.

No formal action was taken. Council members asked staff to keep Corbridge informed and to continue reviewing drainage and stormwater implications for proposed development in the area. Councilors and staff noted that some items — such as subterranean flow paths and gravel layers that guide groundwater — are geologic in nature and that resolving disputes about cause and responsibility often requires specialized, and costly, technical studies.