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About jcirish

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    Water Resources
  1. Theoretical Limit of lift to siphon by physics and bernoulli equation (and in most published sources)is about 32.8 ft, decreases with altitude with lower density air. YET in practical life, said lift is about 20 ft at sea level and drops 1 ft per 1000 ft of altitude. Why the great difference? You can NOT lose 12 ft to pipe losses or friction........ I do not think???? thanx, john
  2. Roger. Have hired local engr firm. Scour would be from when water stages high enough and causes flow in submerged pipe on pond bottom. Plus, Scour is from outfall of the pond, 2 stage weir with no baffles or vel. dissipators....... at end of stilling pond is gully that has been carved into soils at treeline..... or end of stilling pond. Water was supposed to sheetflow but gully opened in spot right in line with middle of weir notch, deepest point of weir opening and source of highest vel. of flow. thanx, john
  3. Fl and county just 4 laned road by me. If permanent pool of wet detention pond extends way back into the inlet pipe..... inlet pipe of Pond 1 for SR 415 is 2.2 ft submerged always. It's top elev is 5.5 ft (invert is at 6 inches and pipe is 5 ft diam) and permanent pool elev is 8.7. I believe a backwater is created in the inlet pipe up to the 8.7 ft elevation... way upstream in the pipes feeding this pond. I think, this is HUGE problem cause flat inlet drain on SR 415 S side has 54 in or 4.5 ft inlet pipe whose invert is ONLY 3 ft, thus top of pipe is 7.5. This pipe is thus ALWAYS full due to perm pool elevation of pond 1. When design storm of 8.6 in in 24 hrs hits.... this pipe will not be able to handle all the inflows due to high tailwater induced by pond perm pool. Issues: water stagnates in inlet pipe, breeds mosquitoes (zika and other dangers); drainage from SR 415 will NOT work properly due to high tailwater behind curb inlets..... pipes close to pond are 100% full for quite a distance BACK from pond (due to backwater of the perm pool.) And the design calculations reports did NOT state that they addressed a high tailwater condition for the pipes close to pond 1 or inlet pipe of same pond. I think there will be slow/little drainage in some curb inlets and high risk of hydroplaning. They reused a borrow pit for pond 1 should have put it further N at higher elevation and used exfiltration trenches in low spots near Reed Ellis rd like they did in flood plain of river. I suspect under 25yr/24 hr storm water may bubble up out of some flat inlets on side of sr 415. Am I off mark...... what other issues are there..... scour on pond bottom and turbidity? thanx, john
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