Large System Water Pressure Discussion

Discussion in 'Irrigation' started by Irrigation Contractor, Sep 16, 2012.

  1. Irrigation Contractor

    Irrigation Contractor LawnSite Senior Member
    Posts: 380

    First a little history and site description:

    We are currently installing and maintaining a system that at this point is 516 - 45 - 75 gpm zones. 7 - Rainbird LXD and 2 - Tucor RKD controllers with 17 water meters and 5 water wells.

    This is a large residential community growing very fast (150 - 175 homes a year) so the city water lines (West Side) come in from both sides of the community. One 12" city main comes from the newly developed side and another 10" city main comes into the other end of the community (East Side) after is supplies 10 year old plus neighborhood.

    Water pressure on the west side is around 90 psi and the east side is 50 psi which is where our issues are coming. Now, we have spoken with the utility and physically check all of the city isolation valves to verify they are open. I have the city main as-builds that show the water line crossing the major blvd in this community and we have at times a 40 psi difference literally crossing this blvd. There is a elevation change that we estimate is 35' from one 2" meter reading 89 psi to another 2" reading 51 psi.

    ***Now that I have put all of you to sleep:hammerhead: Seriously, I just wanted to put it all out there and provide all the details:
    Several RB 5505 zones run #8 to #12 at 65-70 gpm and for this discussion we had 2 zones going at the same time. Meter A had static pressure of 91 psi and meter B has 49, but meter B was moving 10 gpm and A was ripping at 120 gpm.

    I am assuming the back pressure from meter A is keeping B meters volume down since 5505's are nozzled to operate at 50 psi. We have plenty of water to run 3 zones technically, but meter B operating at an even lower dynamic pressure really affects the larger rotor zones.

    I have dealt with pressure problems over the last 15 years and if I am right the only solution is going to be installing a booster pump for meter B.

    I really want to know your thoughts and if I am seeing this the wrong way I definitely want to know! Sorry for the long post and boring read, but I need to address this problem with management and I really want to be prepared and be able to present solutions. Thank you in advance for your replies and assistance:clapping:

    Side note: This is happening with several areas in this community, so do not get hung up with the scheduling of the zones. Our biggest issue with all of this right now is the water window.
     
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,003

    is the planning and infrastructure adequate? Are the towns and utilities making effective plans for water consumption?
     
  3. Irrigation Contractor

    Irrigation Contractor LawnSite Senior Member
    Posts: 380

    I spoke with the Civil Engineer who stated the line size is correct for the community we are working in, but I cannot confirm anything out side of the community more than a half a mile out that is no shown on the drawings I have got my hands on. The water department tied in a 8" line on the east side a year ago that heads down towards a part of town that is not so developed yet.

    I just cannot understand how literally across the street we have such a variance in pressure. The water department is NO help at all and when it comes down to answering the tough questions, the quote state law which is "They only only required to provide 25 psi at the curb stop or meter".

    This is not only a pain for the common area, but try being contacted to install homes where some are 50 and others 90. Low Pressure = Irrigation Contractors Nightmares:confused:
     
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,003

    Hello, Maxipaws :p
     
  5. hoskm01

    hoskm01 LawnSite Fanatic
    Posts: 5,690

    Upsell time to pumps. $$$
     
  6. Irrigation Contractor

    Irrigation Contractor LawnSite Senior Member
    Posts: 380

    That is where I am at right now since I feel we have exhausted any options. Since the community is growing so rapidly, I was hoping once a couple of key "sections" water lines were installed that completed a loop the pressure would increase, but that happened long ago.

    The site is just to big to deal with smaller zones or nozzle adjustments, we already submitted the pricing for the booster pumps.

    I just was hoping others have seen this situation and could provide some details. The water department sucks to deal with and I could easily see them being able to increase the city pressure on purpose or once more infrastructure is put in place.
     
  7. mitchgo

    mitchgo LawnSite Silver Member
    Posts: 2,769

    Must be a PRV on the city somewhere they aren't telling you about.

    I got a street that on one side it's 80 PSI and the other side it's 40 PSI. Same water tower. On a hill top.
     
  8. 1idejim

    1idejim LawnSite Fanatic
    Posts: 9,131

    Or leaks. Leaks won't be acknowledged without the cooperation of the water gods though. Corralation would seem to be a sensible approach.
    Posted via Mobile Device
     
  9. stebs

    stebs LawnSite Senior Member
    Posts: 368

    Any chance you can sweet talk the city water gods into letting you shut this section of line down long enough to run a camera down through it?
     
  10. 1idejim

    1idejim LawnSite Fanatic
    Posts: 9,131

    Noise/vibration corralators don't require systems to be shut down.
    Posted via Mobile Device
     

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