Thank you for the very informative web site.
I looked through the reports. Most of the recommendations such as purchasing property in the flood plain and future development restrictions will have little effect. The one recommendation that will have significant, almost immediate flood mediation is the replacement of the Beatties Dam with a modern dam with flood control gates. (I would prefer getting rid of the dam period. If I did not exist, it would never get the authorization to be built today. Many older dams throughout the USA are being removed with federal funding)
In looking at flood guages:
· The Pine Brook datum is 149.26'. The 5% low flow gauge is 12.5' Therefore, the 5% low flow elevation above sea level is 161.76' (149.26 +12.5)
·The Two Bridges datum is 155.0'. The 5% low flow gauge is 3.8' Therefore, the 5% low flow elevation above sea level is 158.8'' (155.0 + 3.8)
· The Beatties Dam elevation is 158.3'
· The difference in low flow elevation from Pine Brook to Two Bridges is 2.96' (161.76' - 158.8'). The river is about 10 miles from Pine Brook to Two Bridges. So the grade is about 0.3' per mile (which is why it takes so long to drain the river after a flood.)
· The difference in low flow elevation from Two Bridges to Beatties Dam is is 0.5' (158.8'- 158.3). The river is about 2 miles from Two Bridges to Beatties Dam. So the grade is about 0.25' per mile - almost nonexistent. The grade is grossly inadequate to handle the flow of both the Passaic and Pompton Rivers during a flood.
· The dam is 8.3' high. So, the natural river elevation at the dam is 150.0'. If the dam did not exist, the grade from Two Bridges to the Beatties Dam would be 2.9' ((158.8' - 150.0') / 2) per mile. The dam severly restricts the natural river flow and the result is catastrophic to Fairfield, Wayne and Lincoln Park floods.
· At a Little Falls Township Council Meeting on April 29, 2010, it was stated that a replacement Beatties dam would lower peak flood elevations by 3.5' at the Route 23 Bridge in Wayne. Imaging how a 3.5 drop in peak flood levels would mitigate Fairfield's flood damage? it was noted that downstream flows would increase by 1-2 inches . Note: it is much easier to mitigate 1-2 inches than 3.5'
My Recommendation: We do not need more studies. The Corps of Engineers 1989 cost estimate to replace Beatties Dam is 38.5 M$. Today's cost is probably about 100M$. This is a relatively low cost. Compare it to the State's 500M$ increase in Abbott School Funding this year. Defunding the Federal Corporation for Public Broadcasting for two months would more than pay the entire cost of the project. With any new project, we must also look at the unintended consequences. If opening the new Beatties Dam flood gates caused a severe problem downstream, the gates could just remain closed during high water flow- no permanent harm done. However, if we had the new dam in place, we could have drained the Fairfield flood basin in anticipation of tropical storm Lee (with no adverse impact to downstream communities) and this action would have mitigated today's damage. Also, opening the flood gates at the end of the flood would hasten the lowering of flood waters in our town.
Beatties Dam looking upstream.
Beatties Dam looking downstream.