Are you sure it's not an infiltration system for stormwater runoff. These systems are becoming more popular since they require less land to deal with runoff. Highbeam is right about the requirements here in washington. I'm a licensed installer in our county and in most cases burying a drainfield more than 24 inches will result in the dept of Health disapproving your installation.
leech field
- Thread starter par4thecourse
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DKinWA,
What county are you licensed for? I'm up in Snohomish County. A few months ago I got my permit for a gravity system. designed by licensed engineer. Trench depth is 3 feet. 2 inches of gravel in the bottom and then 4inch pipe. That will put my drainfeild at 30 inches below grade. So I guess my question is; what is the deciding factor when the engineer or county sets the trench depth? I figure it must be the soil type?
What county are you licensed for? I'm up in Snohomish County. A few months ago I got my permit for a gravity system. designed by licensed engineer. Trench depth is 3 feet. 2 inches of gravel in the bottom and then 4inch pipe. That will put my drainfeild at 30 inches below grade. So I guess my question is; what is the deciding factor when the engineer or county sets the trench depth? I figure it must be the soil type?
Luremaker
Veteran Member
Highbeam, my septic system is 33 yrs old and the top of the tank itself is 6' below grade and the leech field is between 3' and 5' below grade. My leech field is located on a sloped front lawn. We have never had any problems with the system. The tank is pumped every 2 yrs and inspected and has always passed. I know of a number of leech fields around here which are below 3 feet. They all seem to work.
8561
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Absolutely positive. I used to adjust insurance claims and saw it while it was dug up. There was an issue with it (not at all related to design or location) and they were claiming the damages against their policy.
In Washington state, residential systems are typically permitted by the local government. Larger systems fall under the jurisdiction of the Dept of Ecology. I had to do some digging online, but I found the EPA onsite wasterwater manual . This was required reading when I tested for my installers license in GH county. I've got the printed copy and it's almost 2 inches thick and I fell asleep many times trying to get through it /forums/images/graemlins/grin.gif
I refer to it fairly regularly, but section 4.4 has design guidelines they recommend all systems meet and folks might find it interesting. Other parts of the manual go into very specific design criteria, but soil type is probably the primary factor in determining the design.
I'm far from being a designer (I just put'em in the ground), but I'm surprised they can make a drainfield work under a paved parking lot. I'm not even sure I understand how it'd work in this instance /forums/images/graemlins/confused.gif
I talked to another installer about burying the drainfield deeper than installed and we came to the following conclusion. The plumbing fixtues in the home will most likely drain as intended for many many years. The only question left in our mind was, "since it will be more difficult for the excess water in the drainfield to evaporate, is there a greater chance of contaminating groundwater?".
I refer to it fairly regularly, but section 4.4 has design guidelines they recommend all systems meet and folks might find it interesting. Other parts of the manual go into very specific design criteria, but soil type is probably the primary factor in determining the design.
I'm far from being a designer (I just put'em in the ground), but I'm surprised they can make a drainfield work under a paved parking lot. I'm not even sure I understand how it'd work in this instance /forums/images/graemlins/confused.gif
I talked to another installer about burying the drainfield deeper than installed and we came to the following conclusion. The plumbing fixtues in the home will most likely drain as intended for many many years. The only question left in our mind was, "since it will be more difficult for the excess water in the drainfield to evaporate, is there a greater chance of contaminating groundwater?".
Egon
Epic Contributor
</font><font color="blue" class="small">( I'm not even sure I understand how it'd work in this instance )</font>
It dosen't work properly. The effluent just drains into the exsiting soil with no anerobic action.
Egon
It dosen't work properly. The effluent just drains into the exsiting soil with no anerobic action.
Egon
OP
par4thecourse
New member
Well... Thank you all for the info. All things considered I'll add as little depth to the leech field area as possible to allow for mowing.
par4thecourse
par4thecourse
Highbeam
Super Member
"It dosen't work properly. The effluent just drains into the exsiting soil with no anerobic action." Bingo. Not that the toilet won't flush, you just run the chance of ruining your/my well.
DKinWA, you being an installer and me being a PE..... I've gotten a few systems through the approval process and really enjoy it. The problem is that as an engineer my price can be undercut by a "designer" working out of his garage.
Septic systems are amazingly simple to design, we don't use perc tests anymore but instead rely on textural analysis to determine what type of soil is in the hole and then printed tables tell us what rate of infiltration to use. Assume a flow rate based on bedrooms and bang, the length of trench falls out. The rest is just layout and standard details. When you get into sand filters, recirculating gravel filters, or mound systems things get more interesting.
DKinWA, you being an installer and me being a PE..... I've gotten a few systems through the approval process and really enjoy it. The problem is that as an engineer my price can be undercut by a "designer" working out of his garage.
Septic systems are amazingly simple to design, we don't use perc tests anymore but instead rely on textural analysis to determine what type of soil is in the hole and then printed tables tell us what rate of infiltration to use. Assume a flow rate based on bedrooms and bang, the length of trench falls out. The rest is just layout and standard details. When you get into sand filters, recirculating gravel filters, or mound systems things get more interesting.
HammerFour
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Don't most systems have a septic tank where the anerobic action takes place? I would think you would want the tank to be the place where the breakdown if the wastes takes place with the leach field being where the fluids go after the tank to soak into the soil, right?
Or are there systems that have the toilets hooked directly to the leech fields? I would think those leach fields would shortly plug and be unusable....
Or are there systems that have the toilets hooked directly to the leech fields? I would think those leach fields would shortly plug and be unusable....
