Tricky Drainage Situation with SRW

Discussion in 'Hardscaping' started by JimLewis, Jan 27, 2011.

  1. JimLewis

    JimLewis LawnSite Fanatic
    Posts: 6,835

    So we are often working in fairly tight sub-division like neighborhoods, where houses are packed in tight very close to one another. Also, in the areas we work in there is often quite a large elevation change even from your front yard to your back yard. But even more elevation change from your property to your neighbors property, in a lot of cases. Sometimes the neighbor's house just 50' behind you can be 10-20' lower in elevation.

    So a common challenge for us in this situation is; Where do we outlet the drain pipe when we are installing an SRW for the upper property and the person in the lower property doesn't want anything to do with the job? That is, they don't want us to tie into their drainage system. So then the problem is how do I build the SRW when you can't outlet the drain pipe anywhere? I can't dump it onto the neighbor's property and they don't want me tying into their drain system. So how would you build this, then? Normally, I like to include a 3" or 4" drain pipe at the bottom of the gravel drain behind the wall. But in this case, I don't see a purpose for installing the pipe if there's nowhere to outlet it to.

    Let's keep it simple. Say we're talking about a basic 4' tall SRW with not much of a slope or surcharge above it. (See attached image).

    Would you just install a nice big gravel drain behind the wall and fore-go the ADS drain pipe? Is a gravel drain behind an SRW by itself enough to keep hydrostatic pressure from building up behind the wall? Keep in mind we have a LOT of rain here in the NW. So hydrostatic pressure is always a big concern when building these.

    SRW Diagram.jpg
     
  2. JimLewis

    JimLewis LawnSite Fanatic
    Posts: 6,835

    Actually, a more common scenario would be more like this diagram......


    .

    SRW Diagram2.jpg
     
  3. Danscapes

    Danscapes LawnSite Senior Member
    Posts: 331

    Drain it out of the block on the ground. Use a piece of sch 40 to get through the block, cut flush with the front of the block and put a screen on the end. I don't see a problem really.......the runoff would be the same with just the slope of the yard right? Only difference is, now they are get filtered water.Thumbs Up
     
  4. JimLewis

    JimLewis LawnSite Fanatic
    Posts: 6,835

    I would agree. Except that drainage is already such a huge problem around here that people freak out when you even think of dumping an additional drainage onto their property. They won't go for it. We'd have some major problems if we tried to do that with most people around here. So that's really not an option. There isn't really an option in this case to outlet a pipe anywhere. That's what I am saying. So in that scenario - where you can't outlet a pipe at all - do you just build it without any drain pipe?
     
  5. zturncutter

    zturncutter LawnSite Bronze Member
    Posts: 1,308

    Could you build a 2nd dry well up slope from the wall with perforated pipe filled with gravel, sunk vertical and hide it as part of a landscape feature.
     
  6. Swampy

    Swampy LawnSite Bronze Member
    Posts: 1,435

    Could you have it dump into a "Aqua block"?
     
  7. JimLewis

    JimLewis LawnSite Fanatic
    Posts: 6,835

    You could. That's what I did on the last one of these - but I was just doing it to make the homeowner happy. They really don't work here. They get totally full and overwhelmed first big rain storm of the season.

    Every dry well, NDS Flo-well system, underground basin, etc. I've ever installed has never worked. First time we get a heavy rain in the fall the customer calls back and says it isn't working. I go check it out and sure enough it is totally full - in less than 1 day. Last one this happened to was a series of 4 NDS flo-wells in a hole we made with a backhoe that was about 12' deep and 5' wide. It had several hundred gallon capacity and filled up first big rain. We ended up digging it up, abandoning it, and re-routing the drain pipes to a lower place on that property a long ways away.

    Anyway, long story short, those don't work here. Only way they work is if create a flo-well and then install a sump pump inside it and pump it back up to a drainage outlet higher up on the property. But this is less than ideal.
     
  8. zturncutter

    zturncutter LawnSite Bronze Member
    Posts: 1,308

    The only other option I could see would be to install danscapes suggestion, build the wall back about a foot off the property line and install a border of gravel on the outside of the wall to cover the pipe ends. Like he said they are not getting any water they would not have gotten anyway and this way they don't see the pipe and the water gets dispersed a bit better.
     
  9. silverado212

    silverado212 LawnSite Senior Member
    Posts: 373

    I know where I live there are no codes as far as drain lines go. So I would agree with the above if you can. Build the wall back a foot from the propertyline and dump out through the block. I don't know what your codes are but if nothing else the drainage would still be on the owner of the walls property.
     
  10. mrusk

    mrusk LawnSite Gold Member
    Posts: 3,260

    Just dig a 4x4 hole. Line with filter fabric and fill with clean stone.
     

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