The pond was drawn before it was sized

Anyone who has drawn a detention pond on a preliminary plat knows it went where there was room. The numbers come later, after the comment letter, when the lots beside it are counted. And the big storm rarely sets the size.

One case on our Try page: a detention pond, which Yesper sized against the Eastern Washington manual. It holds the 25-year storm but fails the 2-year release limit, and needs at least 181 ft, not the 170 on the plat. The culvert under the state route fails on WSDOT's minimums, not on flow.

The pond gets its size while the plat can still move, not in the stormwater report after it's gone out. Same for the neighbouring jobs on the Try page: a work plan for a culvert, a settlement calculation check, an earthwork balance with the contaminated soil counted.

Try it yourself →