I live in a small neighborhood of 26 home owners in Goochland County.  Our neighborhood has a small 9 acre community lake.  The VA Department of Conservation and Recreation (DCR) informed us last year that we must comply with state regulations under the Dam Safety Act.  We have hired an engineering firm to help us understand our obligations and to help design and oversee mitigation activities.  So far, we have spent $31,000.  We are not yet sure what the final cost will be to our home owners, but it is likely to be in excess of $100,000.  This is a lot of money for 26 families to bear.

While I cannot fault the DCR or the intent of the Dam Safety Act, what is troublesome is the assumption of the Probable Maximum Precipitation (PMP) upon which the analysis, and thus the resulting mitigation, is based.  The PMP was determined by a 2015 study found here: https://www.dcr.virginia.gov/dam-safety-and-floodplains/document/pmp-final-report.pdf.

Our dam is required to withstand a Probable Maximum Precipitation rainfall event of 28.9 inches within a 6 hour period.  This enormous amount of rain would overtop our dam and possibly cause damage to VA State Route 6 downstream, according to the analysis done thus far.

While I am sympathetic to DCR’s obligations for dam safety, I do think the Probable Maximum Precipitation assumptions should be reasonable.  I think 28.9 inches in a 6 hour period is not reasonable, nor probable.

And I wonder if Goochland gets 28.9 inches of rain within 6 hours,  what possible difference our 9 acre lake could make, whether the dam withstands the event or totally collapses.