pdr
01-21-2012, 12:02 PM
We just set up the sugarhouse in portion of my father's old dairy barn. A small stream flows past the barn and then immediately under the highway through a 60" outside diameter corregated steel culvert. When the County installed that culvert over a decade ago, they also raised the highway in that area several feet. Unfortunately, that highway fill now acts as a dam with the barn/sugarhouse on the wet side. And you guessed it: stormwater from the 400 acre watershed has backed-up 3' deep in the barn a couple of times in subsequent/recent years. Because the road "dam" had always been lower than the barn/driveway, flooding had never occurred there.
I'm embarrassed I didn't consider it much of a problem - having attributed the likely cause of the flooding to tree debris blocking the culvert. (I did not live in the area at the time and only witnessed the muddy aftermath of those storm events)
Now it turns out, according to my father who did witness the flooding, debris was NOT the problem. He swears the pipe was conducting H2O full-bore. Thanks to Table 5.7a on page 79 of the N.A. Maple Syrup Producers Manual, I'm sure his observation was right on the money.
According to that table, a 60" diameter pipe can only drain up to 160 acres! (the minimum diameter for draining 350 acres is 78" - the highest acreage listed on the chart)
I notified the County Highways Dept. engineers of the problem Wednesday PM and they were on site evaluating the situation first thing Thursday morning. They said they will "redo the hydrology" asap, but added that the cost of redoing the culvert would be in the $600,000 range. (I'm hoping that the current engineers aren't the same ones who engineered the structure in the first place!)
Anyway, I'm passing this along for several reasons:
First, I've had a difficult time finding any other culvert size/drainage area tables - and the hydrology formulas are too darn complex for my pea-brain. I want to be fore-armed for addressing the County's engineering results, so I'm wondering if anyone (Dr. Perkins?) can source pg. 79 table - or steer me towards any other drainage/acreage data for that matter.
Second, I am sure that hundreds of culverts have been replaced throughout New England the past few months - and that many will be replaced soon. Just offering a word of caution, a reminder to be vigilant - not all engineers are necessarily created equal ...
Lastly, it's not possible to rewire/replumb/relocate the vac pump, ro, evaporator, wood, etc., so we'll go ahead with sugarin' this year - thankful for lighter-than-average snow pack and hoping for no significant T-storms, hurricane remnants, etc.
Thanks for listening, and any thoughts most welcome.
I'm embarrassed I didn't consider it much of a problem - having attributed the likely cause of the flooding to tree debris blocking the culvert. (I did not live in the area at the time and only witnessed the muddy aftermath of those storm events)
Now it turns out, according to my father who did witness the flooding, debris was NOT the problem. He swears the pipe was conducting H2O full-bore. Thanks to Table 5.7a on page 79 of the N.A. Maple Syrup Producers Manual, I'm sure his observation was right on the money.
According to that table, a 60" diameter pipe can only drain up to 160 acres! (the minimum diameter for draining 350 acres is 78" - the highest acreage listed on the chart)
I notified the County Highways Dept. engineers of the problem Wednesday PM and they were on site evaluating the situation first thing Thursday morning. They said they will "redo the hydrology" asap, but added that the cost of redoing the culvert would be in the $600,000 range. (I'm hoping that the current engineers aren't the same ones who engineered the structure in the first place!)
Anyway, I'm passing this along for several reasons:
First, I've had a difficult time finding any other culvert size/drainage area tables - and the hydrology formulas are too darn complex for my pea-brain. I want to be fore-armed for addressing the County's engineering results, so I'm wondering if anyone (Dr. Perkins?) can source pg. 79 table - or steer me towards any other drainage/acreage data for that matter.
Second, I am sure that hundreds of culverts have been replaced throughout New England the past few months - and that many will be replaced soon. Just offering a word of caution, a reminder to be vigilant - not all engineers are necessarily created equal ...
Lastly, it's not possible to rewire/replumb/relocate the vac pump, ro, evaporator, wood, etc., so we'll go ahead with sugarin' this year - thankful for lighter-than-average snow pack and hoping for no significant T-storms, hurricane remnants, etc.
Thanks for listening, and any thoughts most welcome.