Storm water runs downhill. Making sure it doesn't cause damage can be expensive.
That's the gist of a storm water drainage plan presented to Bayfield town trustees on Oct. 21.
The plan was done by the town's contract engineer. It includes an inventory of drainage routes, drainage features, which ones can handle five-year and 100-year storm events, and which ones meet current town infrastructure standards.
Town Manager Chris La May gave a run-down of the plan and cited costs estimated at $1.7 million as some of the things that will be paid out of an additional 1 percent of town sales tax if voters approve it on Tuesday, Nov. 4.
Mayor Rick Smith commented, "It's just another reason why we really need that sales tax."
Sixty-four percent of culverts surveyed did not meet design standards for drainage from a five-year storm, and those plus one more culvert don't meet standards for a 100-year storm, La May said. He reported that 36 percent of storm drain pipes do not meet standards for a five-year storm, and 52 percent don't meet standards for a 100-year storm.
The survey lists 21 ponds that would overflow in a five-year storm plus two more that would overflow in a 100-year storm.
La May said the estimate of $1.7 million includes $600,000 for culvert replacement, $400,000 to extend a dead-end storm drain from the west end of the Dove Ranch subdivision under County Road 501 to the river, and $700,000 to replace other drainage infrastructure. The Dove Ranch extension will be the biggest single project.
La May gave a cost estimate of $225,000 to upgrade ponds, which are privately owned and maintained.
The study recommends consideration of regional runoff detention ponds "if we can get property owners to work together," La May said. This would mainly affect future developments, especially land currently outside town limits.
The study is based on topographic maps with two-foot contours. Actual engineering will need to be based on one-foot contours, La May said.