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  1. SMIAH

    Combined sewer - Clarification

    Does sewer network separation increase peak flow rate? e.g. Installing a new stormwater sewer next to an existing sanitary (combined) sewer. More precisely, if and only if the existing combined sewer is not able to carry a certain peak flow, installing a stormwater sewer that has the capacity...
  2. SMIAH

    Submersible Mixer

    We're looking for a submersible mixer to install in a water tower (submersible, powered, recirculation equipment for potable water reservoir). The overall volume of the tank is 1 000 000 US GAL and the maximum water level is 120 ft from ground. The area of the tank is 1200 square feet. Thing...
  3. SMIAH

    I am reviewing a detention pond (Sk

    I am reviewing a detention pond (Sketch attached). The designer determined 2 WSE : 1 for the detention pond maximum water level and 1 for the manhole with control structure maximum water level. Thing is, there's almost 1' between the 2 water levels. I'm guessing intuitively that there is...
  4. SMIAH

    Distance between pipes

    We have a project where we have to place 2 pipes parallel on a water distribution network. The pipe will be made of PVC DR-18 with diameters of 8'' and 6''. What would be the different considerations as to determine the distance between these two pipes? I was thinking of specifying at least...
  5. SMIAH

    Insulation under culvert?

    I recently had to debate with a technician about insulation of culvert. From my perspective, we try to put styrofoam above (horizontal) or as an inverted U around the pipe when we know that we're near the depth of penetration of frost. The technician says that they only put styrofoam under...
  6. SMIAH

    Check valve u/s Air Release Valve

    We have an old sewer force main (6 inches CPV). There is an high point/manhole with a check valve placed upstream the air release valve. It doesn't seem to be working. I would like to know what is advantage of placing a check valve before the air release valve? Should we replace both or just...
  7. SMIAH

    PVC SDR 35 or 28

    Some regulators here ask for wastesewer pipe to be SDR35 PVC while drainage has to be SDR28 PVC. I saw both to be SDR28 and some other ask for SDR28 for wastesewer and 35 for drainage. I'm not sure to see where this all comes from. Any clues?
  8. SMIAH

    1H:1V 300-500 mm rip rap

    I'm reviewing a plan showing 1H:1V rip rap that is about 2 m high. The plan show that rip rap is "Crushed stones 300-500 mm (it can be dynamited rock)" No filter (granular or textile) behind it. I am skeptical about the fact that anything steeper than 1.5H:1V will be stable. Am I wrong?
  9. SMIAH

    N-Impeller Clog

    thread378-310492 I am reviewing a N-Impeller Clog proposed pump where it was clearly stated that solids this pump is capable of passing has to be 4 inches. Wondering why Xylem can't claim that their Neva Clog impeller are capable of passing x inches debris. Can someone provide more...
  10. SMIAH

    HDPE corrugated/profile vs RCP

    I am reviewing a detention basin (low earth-dam) proposed with HDPE corrugated pipe as the evacuation system. It will have to work with max 4 ft of water over the top of the pipe. We normaly accept these with an RCP pipe and I say that corrugated HDPE is not a equivalent to RCP. But what if...
  11. SMIAH

    Sewer separation projects

    I am trying to find a way to estimate the equivalent population of a combined sewer separation. Well it's not my idea but I have to do it :) Using : Area (road) = 1000 m length x 10 m wide. Rainfall = 10 mm of rain on a 3-hour duration Chicago storm CN = 98 (road) Initial abstraction Ia =...
  12. SMIAH

    Rising main

    Im am having an argumentation with a colleague about 2 options for a discharge line. Option 1 = actual design (discharge line ending up at the hill point, then gravitary). Option 2 = design modified (discharge line ending up to the downstream point). He's pretending that the pumping flow...
  13. SMIAH

    HDPE to stainless steel 316L transition

    What flexible fitting should be used for a transition from HDPE (8" DR-17) to a 8" Stainless steel 316L pipe in a corrosive environment?
  14. SMIAH

    Critical duration under TC

    Might be an easy one (yes or no) : When seeking a volume from the Modified Rational Method,the calculation is performed at multiple durations with corresponding intensities to produce a series of trapezoidal hydrographs. Once the allowable discharge is subtracted the hydrograph with the...
  15. SMIAH

    Valve on a biogas vacuum line

    Looking to install a valve to put on a HDPE pipeline vacuum biogas. There will be a valve chamber and we're looking for the best product in terms of maintenance and ease of use. Diameter are ranging from 3/4 inches to 8 inches.
  16. SMIAH

    Slab-on-grade

    Building my first house with a slab-on-grade (3 1/2'') + frost walls (4'-6'' min) and a footing (30'' x 10''). The excavation works has been completed yesterday evening. I was hoping for a rock foundation but instead I got a sandy-silt. Asked to add a drain tile near the footing but the...
  17. SMIAH

    Modified rational formula

    Isn't there something with this particular method about the fact that the duration of the storm has to match or be near the time of concentration of the watershed ? Calculating small detention basin, I see that the duration that control the required volume is sometimes way more than the time...
  18. SMIAH

    Deadend waterline

    A water pipe will be installed with a check valve so that the flow from network #1 can come in support to network #2 if the pressure drops (e.g fire protection). Under normal conditions, the static pressure in network 1 = 68 PSI and the static pressure in network 2 = 129 PSI. When network 2...
  19. SMIAH

    NPSH dry-well submersible installation

    We're in the process of replacing old conventional (dry well) pumps with submersible pumps and I was wondering if NPSHa could be an issue.
  20. SMIAH

    Similitude of events + outlet device

    I'm working on a retention basin proposal for a 75 acres semi-urban development. The design criteria is Qpeak pre = Qpeak post-conditions for 2-year to 100-year (usual day at the office there). The basin outlet has to be in stream draining a watershed of approx. 750 acres. And the slope...

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