Locating septic leach field

[seapea]

Does anyone know how to locate a leach field? I know around where it is, but want more precise location information because we may be putting up a structure close by. I know the direction the line runs out from the septic tank. I also know it intersects the corner of the leach field at a 135 degree angle.

I suppose I could start trenching with a backhoe around 30 feet away from the septic tank until I hit gravel, and then follow the gravel until I reach the corner of the leach field. However, I was hoping for something less intrusive. Is there any way to detect the presence of the leach field (please, no divining for water suggestions).

 

[Junkman]

Depending on how old your system is, your local health department might have the original plans of file. If that isn't a viable alternative, then try to borrow a metal detector and see if you can locate the distribution box. Usually they have a handle on top made of rebar, so the metal detector will pick it up. You can also look for the area that the weeds or grass appear to be greener in color than the surrounding area, since they are nourished by the water from the system. Also, you might ask the neighbors who the local installer is that was used when it was installed. A little detective work will save you a lot of digging if you approach this with a open mind.

 

[DKinWA]

You can use a smooth metal rod to probe the ground to find the gravel in the drainfield. If the ground is really hard, you can water the day before or drive the rod in with a hammer. I've got a couple that I use made of 3/8" stainless steel rod with handles welded on them. Around here, gravity systems are typically 18-30 inches deep, so they aren't too hard to find. It helps if there's a point on the end of the rod that isn't too sharp but slightly larger in diameter than the rod itself (less friction when pulling the rod out).

It helps if you use some string and paint to lay out a grid and start probing. Our laterals are 36" wide so a grid on 18-24" usually works fine. It's a lot of work, but it's doable.

On edit:
Junkman has some good suggestions and I'd try them first. I outlined what I do as a last resort if I don't come up with anything using his suggestions.

 

[seapea]

I should have mentioned that the leach field 6' or more deep, so there is no way to probe for it, and there are no visible signs of it terms of faster growing vegetation. Also, I doubt a metal detector would work that far deep when trying to locate the distribution box.

There are few reasons it is so deep. First, the house was originally built for a person in a wheelchair, so it is very low to the ground. There are no steps into the house, even from the garage. Rather than grading up to the house, they just kind of dug a hole for it. Makes for a very wet and cramped crawlspace. Also, the house is very long, with a bathroom on one side and the septic tank on the opposite corner. As a result of all this the septic tank if quite far below ground, and the pipe that drains out of the septic tank to the leach field is out 3' to 4' below grade. Add to this a slightly uphill slope to the leach field and about 100' of distance, and I figure the leach field must be at least 6' deep.

I do have the original plans to the house, which do show the leach field and septic tank. However, the builder deviated quite a bit from the plans in terms of how things are positioned. The house was moved, the septic tank ended up much closer to the house, the utilities are on the opposite side of the house than shown in the plans, and the well is about 10' off. Because of all this, I doubt the leach field is exactly as show, although it is in the general area.

I'll contact the county and see if they can help. The house was built in 1976.

 

[Junkman]

I can't imagine a leach field that was approved being 6' below ground. 2 - 3 feet below the surface is the norm. In fact, with the leach field that far below grade, I can't see how there can be any evaporation from the system at all and the water has to be just filtering down into the rest of the aquifer, which isn't a desirable condition. Have you had your well tested for coliform bacteria recently??????

 

[seapea]

</font><font color="blue" class="small">( I can't imagine a leach field that was approved being 6' below ground. 2 - 3 feet below the surface is the norm. In fact, with the leach field that far below grade, I can't see how there can be any evaporation from the system at all and the water has to be just filtering down into the rest of the aquifer, which isn't a desirable condition. Have you had your well tested for coliform bacteria recently?????? )</font>

Well, it is what it is. I just called the county and they have records for both leach field installations: the original in 1977 and the 2nd field put in 1992. I'm waiting now for them to be faxed.

I know exactly where the newer field is because it has inspection pipes at the corners (4" capped drain pipes that stick up out of the ground about 18"). I've dropped a tape measure into them. The nearest one hits some muck at a bit over 6' (not counting the 18" sticking up). The ones that are furthest up the grade are closer to 7'. I'm assuming the pipe is at least another foot below them, so that's why I've been saying they are 6' to 8' deep.

As for leaching into the aquifers, wells around here are about 100' deep. Also, I think no matter how deep your leach field is, the presumption is that it leaches into the aquifer. If it didn't, that would imply that the flow of water in the area is up towards the surface, not down towards the aquifer. I don't think upward flow is typical except in very dry regions.

I've never had the tank tested for coliform. I've also never heard of having this done. If it did have coliform, I would assume there is no way to get rid of it. Also, it seems like coliform would readily spread to pretty much ever septic tank in the area via the septic pumping service, unless they sanitize their equipment between each service.

 

[erich]

I'll probably get in trouble for this but here goes. I am not sure what your aversion to divining for water is but as a born again believer I had problems with divining for water schemes also. As a mechanical engineer with a master's degree I had problems with divining for water schemes. As a Second Lieutenant Air Force Civil Engineeering Officer I watched the senior civilian plumber on base accurately locate underground pipes with two bent brazing rods....not steel, not two willow stiks or a willow crotch but two bent brazing rods. I pulled his chain about being so old he was there when the dirt that covered those pipes was made so of course he knew where the pipes were. That's when he handed the rods to me and told me to see for myself. Considering my reservations both scientific and biblical I really did not think it would work. It did. I have used bent rods to locate pipes and electric lines since then. Don't ask me how it works, I don't know and I have had enough science to have a pretty good clue about most things. I thought that it might have something to do with magnetism but considering the brazing rods it couldn't be that. Another weird thing is once you locate the pipe you can use one rod to determine the direction of flow in a pipe. I cannot determine depth but only horizontal alignment. I do believe that divining for treasure or to determine the future is not biblical but I am not convinced that finding pipes or electric lines is witchcraft. It is like the difference between astrology and using the signs in the heavens to plant by. The Lord gave us the signs in the heavens as an aide to time keeping and as a calander, read the Hebrew scriptures (AKA Old Testament). I think at some point there will be a rational explanation for the phenomena. I think that the current flow in electric lines may have something to do with it and the water flow in a pipe over time may have an effect on something in the pipe. I have not tried it on PVC pipe so I can't make any correlations between that and steel or cast iron. If your reasons for not using it are not biblical, don't scoff at it, it works. I don't know if works for all people but it has for me.

Eric

 

[seapea]

</font><font color="blue" class="small">( Depending on how old your system is, your local health department might have the original plans of file.)</font>

This worked out. Got the approvals for both plans. The old field wasn't located quite where I thought. I figured the line ran out from the septic tank about 70' before the field started, but it's only about 8'. This is actually good news. Should make it easier to place the barn we are considering building.

 

[RobertN]

County probably sent you "As Built" plans? That is what we got for our house. I guess there's the usual building plan, and then As-Built plans showing where things moved for whatever reasons.

 

[Junkman]

</font><font color="blue" class="small">( I've never had the tank tested for coliform. I've also never heard of having this done. If it did have coliform, I would assume there is no way to get rid of it. Also, it seems like coliform would readily spread to pretty much ever septic tank in the area via the septic pumping service, unless they sanitize their equipment between each service. )</font>

I was referring to having your water well tested, not the septic tank. If you don't have coliform bacteria in your septic tank, there is a bigger problem than you realize... /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[seapea]

</font><font color="blue" class="small">( (I've never had the tank tested for coliform. I've also never heard of having this done. If it did have coliform, I would assume there is no way to get rid of it. Also, it seems like coliform would readily spread to pretty much ever septic tank in the area via the septic pumping service, unless they sanitize their equipment between each service.)

I was referring to having your water well tested, not the septic tank. If you don't have coliform bacteria in your septic tank, there is a bigger problem than you realize... /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif)</font>

Ah yes, I see now you did say "well" and not "tank". I thought it was kind of a strange question. /forums/images/graemlins/blush.gif. Yes, I had it tested for E. Coli and Coliform about a year ago. They both turned up negative. The only risk of biological contaminents in the well water (with our geology) is via the well head. There's no way they could survive 100 feet of leaching.

 

[_RaT_]

<font color="blue"> The only risk of bioligical contaminents in the well water (with our geology) is via the well head. There's no way they could survive 100 feet of leaching. </font>

Thats my understanding to. I am having a percolation and mantle test for two areas at my place on August 3. It will basically tell me if I need a conventional, pressure dosing or sand filter system. I am obviously hoping for a conventional because of costs.

 

[Highbeam]

"I can't imagine a leach field that was approved being 6' below ground. 2 - 3 feet below the surface is the norm. In fact, with the leach field that far below grade, I can't see how there can be any evaporation from the system at all and the water has to be just filtering down into the rest of the aquifer, which isn't a desirable condition."

Standard septic drainfields do NOT utilize evaporation for primary disposal. The effluent is supposed to go down into the earth to be recycled into the aquifer eventually. This is how they are engineered/designed. Drink your pee. On it's way through the shallow soil, the oxygen in the soil allows bacteria to eat some more of the nutrients providing a secondary treatment after the septic tank has had its shot. This is why a deep drainfield is a problem, not much oxygen that far down. So Junkman and I agree that 6 feet is too deep. Not saying that the local approval authority didn't allow it for this special home.

Witching for pipes isn't what I would call a religion. It is physics, flow through a conduit creates a magentic field. Think about how an electromagnet works. Well the magnetic field is aligned with the pipe. Flowing water is pretty much a big electromagnet and the witching rods can react. Many respected folks use the rods.

 

[erich]

Highbeam,

I thought it was magnetism at first too but how do explain the brass rods reacting to it? /forums/images/graemlins/confused.gif Like I said, I have a pretty good science background as an engineer.

Being in the construction business and working mostly on existing structures I would be a little cautious of depending on design drawings. Unless they can be verified as "as builts", drawings only show the intent of the designer. Unforeseen site conditions can cause field changes that often are not documented. I ran into a major problem on the campus last week with incorrect drawings. Thats where locating equipment comes in. In this case we used electronic gear to find the water lines by hooking a transmitter to a fire hydrant and tracing the line with the receiver. There is no doubt that I would try the bent rods on a septic system if I had no access to more sophisticated locating equipment.

 

[Highbeam]

It's got to be the flux or magnetism. I can only guess that the brass rods were an alloy of some sort with a magnetic material. I wouldn't guess it would work with wood either.

We use the locating system you speak of regularly. Hook onto a hydrant or trace wire. Sometimes we have asbestos water mains and we just have to pothole for it. The huge vac trucks can suck a hole right down to the pipe with the help of a little water.

I agree that it is the norm to construct a project different than the plans. As-builts, especially those of a septic system, are very approximate.

 

[turnkey4099]

Erich: re: witching.

It works for me but I am still skeptical. I have found some things (old water lines, neighbors leach field, water) and have also had failures. Mosst of the things I did find and proved out where in the logical place, i.e., leach field. It was in the only spot available. Water - in this country you will hit water anywhere you drill so my 2 shots at it didn't prove anything.
Water line - had a break in a 1/4 mile line. Traced it out all the way to the well head and terminus in an abandonded school house. Great. Only problem was when I tore down the school house the water line actually entered the school 90 degrees away from where the rods said. Did dig in one indicated spot to try to find the pipe - no luck.

As to material. Any metal works for me. I have even used hunks of barb wire taken off a fence. Mostly use the welding rods.

Depth. When my well was dug the witcher gave me a quick lesson. May not do it for you. As I walk along the rods cross, I mark the spot, continue in same line. Rods cross again somewhere out there, mark spot. Count paces back to original mark, multiply by 5 gives depth in feet. That was checked against another witcher. Without either watching the other we both came up with the same figure and yes that is where they struck.

Bottom line. It is fun to play with but I don't trust it.

Harry K

 

[seapea]

Well, it seems my initial request to leave out dowsing/diving has been ignored. I've been holding off my urge to reply/debunk, hoping the responses would just stop if I kept quite. I know many of you believe, but I don't, which is why I was hoping to focus answers to ones I would find useful.

In any case, if you know someone who can dowse, there's $1,000,000 reward waiting to be claimed by this person. Related to this reward, you may also want to read </font> Randi on dowsing. You might also be interested in the following excerpt from skeptic FAQ

<font color="red"> Unfortunately careful tests of dowsers have revealed absolutely no ability to find water or anything else by extra-sensory perception. Dowsing success stories can be explained by noting that wherever you dig you will find water. You just have to dig deep enough. It has also been suggested that dowsers may unconsciously use clues in the environment.</font>

You can respond with your numerous reports of successes and with stories of "studies" done to prove dousing works. I will just let them be. I suggest you don't let anecdotal evidence sway you. I also will suggest that you don't be swayed by studies that are not truly scientific and have been reproduced by at least an one disinterested group (there have been none).

 

[slowrev]

One drastic method that will work, pour about 5 gallons of brushkiller down the toilet and see where stuff dies /forums/images/graemlins/smile.gif


Disclaimer: Don't try this at home.

 

[NevadaSmith]

ok...leaving the paranormal out of this....

I have an engineering background and am not a scientist...but in regards to dowsing, I would believe it to work (and have seen it) using brass rods. Why? well.... borrowing on my experience in the Navy, and learning about "degaussing' I learned some things that I thought would be science fiction. First...the earth consists of a magnetic field. Second...items passing thru this field distort and bend it, and become magnetised themselves. These principals are used in maritime warfare in many areas....finding submarines and activating mines. Finding submarines are as easy as finding shifts in the fields using a "dowser" ... yup...a dowser (albeit really sophisticated). Knowing this, submarines us a "degaussing coil" to realign the field and throw off the 'dowsers'. Second, ships eventially become "magnetized" as they pass through the magnetic field and develop a unique fingerprint. Every so often, they will wrap ships up in big coils and shoot electricity thru them. Why? because advanced 'dowsers" have been developed to detect the magnetism and activate weapons, and even to identify certain ships. So....ships must be "demagnitzed" every so often.

Now why do I believe dowsing can work? By the same principals as applied above. You hold two brass rods (good conductors) parallel to each other and the earth natural magnetic field will tend to hold them parallel (and induce a very small current when you hold them). When the field is disrupted by items under ground, the rods register the anomolly in the magnetic field by deflecting.

I mgiht be on crack....but it sounds better to me than Uri Gellar and bending spoons. Your links only explain "paranormal" dowsing using sticks, intuition etc.... I'll ignore that and opt for the scientific explanation, which I believe exists. Matter of fact, I do believe underground locating services not only use RF detectors, but magnetic ones as well (again...advanced dowsers).

My two drachmas...so can I have my $1000 now? /forums/images/graemlins/smile.gif

 

[slowrev]

I have also seen dowsing work. You can't convince me otherwise.

I can't make it work, but others can.

Just because it cannot be fully explained does not make it untrue, take gravity for instance......

Ben