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Town staff say Hampton Green yard flooding followed rare back-to-back storms; culvert adequate, repairs done to pipe
Summary
A hydrologic study presented May 27 found the culvert under Whitefriars Lane is sized for a 200-year storm and recommended no dredging of the downstream pond to mitigate the May 2024 flooding; staff said back-to-back large storms and saturated ground caused localized flooding that overwhelmed low-lying yards.
Town staff updated the Board of Commissioners May 27 on a hydrology and hydraulics study of Hampton Green following flooding in 2024.
Public Works staff explained the study found the culvert under Whitefriars Lane was adequately sized for a 200-year storm and that recent on-site repairs addressed identified structural issues. The consultant concluded the most likely cause of the flooding was a sequence of unusually large, back-to-back storms that exceeded the 25-year and in one instance the 100-year event while the ground was already saturated, producing more runoff than the low-lying areas could accommodate.
Staff tested several potential responses. Dredging the downstream pond would increase storage but would not materially reduce the flooding experienced in the yards where water overtopped banks, the consultant told the board. Redefining tributary channels would also have limited benefit: "Streams tend to carve out what they need, and it has already dropped the stream bank by about 3 feet at the bottom of the stream," the consultant said, so the channel had already widened to carry the flows seen.
Sanitary-sewer cleanouts that were observed under water in the incident were raised as a health concern. Staff told residents any detection of fecal coliform or sewage indicators should trigger immediate contact with town utilities for inspection and testing; elevated manhole covers and sealed cleanouts can reduce risk. The town also pointed residents to a potential state-administered stream-bank restoration program through the county conservation district that may be able to help restore eroded private stream banks on eligible properties.
Staff said much of the erosion and bank instability is on private property, limiting what the town can unilaterally do; staff said they will coordinate with residents and the conservation district to pursue mitigation grants and best-practice solutions.
Ending: Staff committed to follow up with Hampton Green residents, coordinate further testing if sanitary systems are compromised, and to notify property owners of options through conservation programs and potential private fixes that avoid creating downstream impacts.
