Replies

1. 
   JimB | Dec 13, 2008 07:54pm | #1

   Having a stream of water flow over a drainfield is just an all-around bad idea, even if it is only seasonally, because it's likely to cause drainfield failure even if the failure is only seasonal.  If it were me, I'd be looking at moving the drainfield as a first choice and as a second choice diverting the water flow around the drainfield.

   I'm curious:  how did the df wind up in such a poor landscape position?

    

1. 
   CoconutMan | Dec 13, 2008 08:56pm | #2

   Options were extremely limited, believe me! The first main drain field was located on an elevated area of the back lawn, but due to the contractors poor slope of the lawn all the roof water had no where to go but into that field. The rest of the property behind the house where the drain field we put it is now, is basically all the same but planted to a small vineyard (i.e slope and drainage being poor)
   The only other choice we could have done would have been to completely rip up the back lawn and do a whole new drain field. Even that would have been next to impossible because it had already failed so the earth was completely saturated.
   I'm stuck with what I'm stuck with.

1. 
   JimB | Dec 14, 2008 04:47am | #4

   My sympathies.  Sounds like a tough situation.  Putting a repair drainfield in the same area as the failing drainfield can be just throwing away money. 

    You definitely want to avoid a second drainfield failure.  Where does the stream originate?  Is there any way to divert it around the df rather than crossing it?

   Incidentally, protect the old drainfield.  It may be usable again in a few years if necessary.

    

1. 
   CoconutMan | Dec 14, 2008 05:04am | #5

   Okay, time for some clarification here.Old drain field is in the "back" lawn. New drain field is about another 30 feet beyond it in the swale (lawn slopes down then back up to property line) between the back lawn and the back property line. New drain field was connected with a diverter valve just past the septic tank thereby maintaining (in the future) a sort of redundant leach field area. Yes, I've been told the same thing. Wait about 3-5 years and the original leach field should "recharge" itself to about 80% of initial capacity. BTW- the next project is to build a french drain around the back patio to capture the roof water runoff and divert it around the back lawn "old" leach field.
   New drain field is high capacity infiltrator "tubes". Three of 'em 60 feet long. The so called "seasonal" stream that goes over the top of the initial 3-5 feet extensions comes from natural drainages in the area. Mother nature, guys! Diverting it would probably entail pumps, probably like a sump pump type of thing- which, I guess, could be done (a dry well??)............
   I'm still not hearing any input on my initial plan of plastic, drainage hoses, and rock. Anyone? Like I said before, I'm stuck with what I'm stuck with. I don't have $40K to build a state of the art leach field......

1. 
   KFC | Dec 14, 2008 06:32am | #6

   your original idea has some hope, if well executed.  you'd be diverting the water over the DF rather than around it, so your margin for error is less.  I'd use multiple layers of poly and round rather than angular stone if I had no other options.  i might be tempted to use pond liner, actually.

   someone who knows more about septic systems than me (that'd be pretty much everyone) may weigh in on the effects of sealing the surface of a leach field with plastic.

   a non-permeable sump and pump is probably a surer bet. 

   k

2. 
   rlaggren | Dec 14, 2008 07:00am | #7

   > trench...Well... Water runs down hill. So anything you do needs a "downhill". If you got a place for it to go, you can get it there; if you _don't_ have a place for it to go... Do you have any "exit" off you property for the water or do you have a marsh?It's not clear if your problem is mostly the house roof drainage, the local surface run off from a rain storm, or if you're receiving a _constant_ flow from "upstream" off your property all during the "rainy" season; if the latter, just how much water do you have to deal with, say in acre feet or thousands of gallons or something. The options vary depending.Regardless of where it comes from your neighbor may have issues with how/where you deliver it to _him_. In that case you need to incorporate some social engineering as well as the hydraulic type. Also, be careful of the local "administrative authority". And if you manage to dump a lot of water onto a road somewhere, you may hear about it big time.But assuming your property isn't the bottom of a water shed, you can probably figure something out - but details rule. If it's just house run-off, you can probably channel that fairly easily. If it's rain storm water, you may be able to dig a "cattle tank" below your field to draw and hold the run off until it seeps into the ground. Think tax credits from creating wetlands! If it comes in acres all season then you need to pass it on to the next guy right away in a way that won't get you into trouble.Just remember that water is one of nature's most powerful and persistent forces. Water _moves_ things so be thoughtful about how you channel it, what it might do to your land or somebody else's over the next 5 years or so - and longer. Trench: Hard pipe flows _much_ better than the corrugated stuff. It's more work, but it's a lot stronger too and it does flex a little. If you do much of it you might want to incorporate to way to rod it out later. Don't run the plastic up the walls of the trench or you'll just keep out the water in the top layer of saturated soil - which is part of what you want to get rid of I _think_ (not sure about the rules about draining the leach field). If the thing drains well, it'll want to suck water into itself from anywhere above it.Rufus

3. 
   CoconutMan | Dec 14, 2008 08:00pm | #9

   Well, it's a combination of both roof runoff and being in the middle of a watershed area so I have two issues to deal with. The watershed issue being the more urgent problem here at this moment.
   You talk about pipe vs corrugated. Is that the stuff that is rigid PVC with the holes in it? I actually thought about it also but I would actually buy the pipe "whole" and drill 3/4" holes in the top half thereby creating a "channel" for the water after it perks down through the rock/gravel. The leach field pipe you can buy has holes around the whole circumference.
   Yes, the trench does slope. The usual 3/4" to three feet or so (I don't have a laser beam, just my eyeballs).
   Anyone have a lead on where I can find 20 mil or so plastic in a 10 X 100 foot configuration in California? I can find back east, but the freight kills the deal- it's almost as much as the plastic is.
   I'm also considering (although not looking forward to actually doing it)a concrete open trough- last resort!

4. 
   JimB | Dec 15, 2008 04:35am | #10

   I wish I had a better understanding of the source of the water and the topography of the property.  A picture is certainly worth a 1000 words, especially on the Internet.

   Any surface water flowing over the drainfield that you can keep on the surface will help.  The problem, though, is that typically shallow groundwater (i.e., in the first couple of feet at least) usually flows in the same pattern as surface water.  So just putting it surface water in a channel over just the drainfield may not solve the problem.  (I'm not saying it won't help at all). 

   Although I don't endorse your idea, I'd think you'd be able to find pond-liner somewhere locally.

5. 
   Snort | Dec 14, 2008 07:10pm | #8

   If, by infiltrator system, you mean the snap together plastic inverted u lines in a graveless trench, you need to be pretty careful about weight like rocks or equipment on top of the lines.With that in mind, you might explore something like a water feature sluice with an epdm liner and thoughtfully placed ballast.Another way to control water is with grass or other water sucking vegetation... amazing how much water that will stop. Now you see this one-eyed midget

   Shouting the word "NOW"

   And you say, "For what reason?"

   And he says, "How?"

   And you say, "What does this mean?"

   And he screams back, "You're a cow

   Give me some milk

   Or else go home"

2. 
   McDesign | Dec 13, 2008 09:28pm | #3

   I remember growing up hating the winter rains, because we couldn't flush the toilets during a rain on soggy ground . .

   Probably injured me psychologically; and why I have seven bathrooms now!

   Forrest