Silt Seperator

Discussion in 'Irrigation' started by Dirty Water, Sep 6, 2006.

  1. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    We have a client with a system on a VERY dirty feed.

    They have a 100 mesh spin down screen. I went up there and the screen was completely clogged. I cleaned it, and it was clogged again within 5 minutes. The water coming in is literally brown.

    Its silt and small organic material. The feed is from a ditch about 100' away and piped in 4" to a pump.

    I don't think installing a solenoid valve on the filter purge will be enough, as it took me literally scrubbing the screen to get it clean.

    I'm wondering if there is a silt seperation system I could use with a regular spindown that wouldn't need daily maintenance?
  2. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    Ok, browsing the net I found this:


    I think the concept is that the water has to into the lower outlet of the Y, and the silt sits on the surface and slowly settles.

    The feed in the irrigation ditch is a concrete catchbasin with a stormdrain on the top, its placed in the bottom of the ditch, so water flows over it.

    If its as simple as glueing a 4" Y to the outline line inside the catchbasin, that would be great.
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,367

    Is it not possible to convert the system to a dirty-water type, with heads and valves to match?
  4. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    Not really, the system is old, this water feed is new.

    Replacing all the valves and heads would be spendy.

    Besides that, with the amount of silt going through the lines, I doubt even a scrubber valve wouldn't have trouble. The stuff going through the strainer is already plugging up Rainbird 1800 filters.

    We would have to switch entirely to impacts.
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,367

    What happened to the old source? I suppose it is possible to get so fouled a water supply that you'd have to have a catchbasin or even a small pond, and to pump water from it.

    Rainbird used to sell backwash strainer systems, for continuous water supplies from crummy sources, but they were very big bucks. You'd change all the heads first.

    How can a 100-mesh-strained water supply clog a strainer under a 1800 spray? Maybe for the smallest nozzles, with their finer-mesh stariners.
  6. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    The old feed is a now defunct well.

    Theres enough crap getting through the strainer to clog up the blue nozzles. I don't know how, but it is.

    So you don't think a silt trap like the one in the picture will help?

    We've talked about installing a large catchbasin (500 gal or so) and pumping from it, except the water will still be filthy.
  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,367

    I would revisit the strainer. You could live with less than 100 mesh. How many GPM? How many acres is the property?
  8. sildoc

    sildoc LawnSite Silver Member
    Messages: 2,925

    The silt is the easy part. It will settle out quicker than the Organic matter of which usually remains in suspension much longer than the silt. Not only that I believe that the reason you are scrubbing is because of the organic matter. Silt usually just washes out fairly easy with house hose bib pressure.
    I have a couple of customers that have the very problem that you have and the way they were approached when they installed it 10 years ago was two small settling ponds of roughly 100' round give or take with 1/4" screen placed between the two to screen large organic to the second pond.
    Now this may help you if they have large property. These props are 10 acres or larger so they had the room when the irr guy did it. On a residential property I would pass it up to one of the older guys and try to learn from them as I have very little experience with dirty water systems.
    what does your supplier have? any thing? I am guessing price is a big factor here as the did not have you revamp the system for DW.

    By the way what is the source? County or city Irrigation district? If so they might have some thought as to how to clean up the water some. Just a thought as most of our irrigation canals are screened to all the non Ag receivers.
  9. bdb

    bdb LawnSite Member
    Messages: 74

  10. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    We have a huge Lakos sand/debris filter on one of our pumps that supplies water to four sites. Kind of spendy for the average homeowner but it does the trick. :)

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