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How to find the soakaway bed, leaching bed, drainfield or drywell for a septic system or seepage pit - method 5: ruling out certain locations. If you can't find the septic tank or drainfield this article helps direct your search by describing visual inspection of the site that will show areas where you can pretty much rule out expecting to find a buried septic tank or drainfield.
A Guide to Finding the Drainfield - Part 5: unlikely septic system component locations
What areas are least likely to contain the drain field, or if they contain a drainfield, are likely
to be a problem?
This article series and our accompanying septic system location videos explains how to find the leach field or drainfield portion of a
septic system. We include sketches and photos that help you learn what to look for, and we
describe several methods useful for finding buried drainfield components. (
Septic drain fields are also called soil absorption systems or seepage beds.) Also see How to Find the Septic Tank.
The septic system video#4 at right describes walking a homesite by a lake in order to reason that the drainfield, which must be not only uphill from the lake but in this case uphill from the septic tank too, cannot be located in the front yard, even though that looks attractive for a drainfield. In the center of the yard we spot the well casing - end of story.
The septic field should not be located here.
A septic pumping system will be needed and the drainfield will have to be located elsewhere on the site, and at a good distance from the well. More videos on septic system location & maintenance are at SEPTIC VIDEOS.
Site areas too close to a drinking water well cannot be used for septic drainfields. See Table of Required Septic Tank, Drainfield, & Well Clearances if you need to reference typical septic component clearance distance guidelines. Our video at the top of this page demonstrates how we discover where the well is located and why that should preclude finding the septic fields in an area that otherwise looked pretty attractive.
Uphill areas, areas that are higher than the elevation of the septic tank are not a first choice to contain the drainfield or leaching beds. Unless a septic pump or effluent pump system are installed (you'd find wiring, and perhaps alarms)
the drain field is going to be at or below the elevation of the septic tank. In other words, down hill
from the septic tank since effluent has to enter a conventional drainfield by gravity..
Naturally nothing prevented the installer from burying the leach lines very deeply in an area which
is, on the surface "uphill" from the tank, but this would be an extra costly installation (more excavation) and
also it would violate good design (leach trenches too deep).
Rocky areas like this should not contain a septic drainfield but sometimes they do - even though a conventional septic system won't work on rock: such as the failed septic system shown at left, and areas where bedrock is exposed on the surface won't make a normal absorption
field.
But beware, we've found non-functioning systems installed in just such a location as the
rocky, steep site shown in the photo at left. The wet marks were water from the septic system leaking
across the hillside.
At the upper center of this photo you can see straw that the owner's contractor piled atop of the septic tank in anticipation that any problems would be hidden from view.
All we had to do was walk downhill at this steep rocky site to see these signs of a totally inadequate septic system installation
Septic effluent running over bare rock
Bare bedrock so close to the soil surface that no working septic drainfield could be installed here without considerably more fill
A septic tank overflow pipe that spills directly onto the soil surface - visible at the bottom center of the straw pile
Swamps or low wet areas, unless the site is using a constructed wetlands for
effluent treatment (such as we show in this area of Mexico in our photo at left) should not contain conventional drainfields.
If the septic fields are too close to a wet area like this the property may be disposing of septic effluent but a conventional tank and drainfield spilling untreated wastewater effluent into a swamp, stream, or lake, is not properly treating it and is contaminating the environment.
Areas with Trees: thickly forested areas are unlikely to contain a drainfield, first
because of the tree root-drain-clog problem and second because the backhoe operator would have a heck of
a time manipulating the excavation equipment in such a tight area. If there is no room to operate
a backhoe it is unlikely that there is a recently-installed drainfield in that area.
This area on a homesite in the Northern U.S. is an unlikely spot to place a drainfield - certainly the presence of trees close together means a backhoe has not been in here digging in many years.
But don't rule out
a very old, overgrown, and ruined drainfield in such a spot at an older property.
Site areas too close to a drinking water well cannot be used for septic drainfields, as we demonstrate in our site-walking septic-locating video at the top of this page.
Our septic search photo at left shows that some well locations are pretty obvious - we don't expect to find the septic tank or drainfield within 75' to 100' of this spot - but we might, depending on the age and size of the building site.
Sites too close to a lake or stream should not contain the septic tank and certainly not the drainfield - but they might
Especially at older, unsupervised, or remote rural properties, the temptation to
simply route effluent leaving the septic tank to a stream, lake, pond is sometimes
overwhelming (though unsanitary and illegal).
This is particularly true at sites
where the soils into which one would have to put the drainfield are rocky, wet,
or where the drainfield has previously failed. We discuss this problem installation further at SURPRISING DRAINFIELD LOCATIONS.
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Frequently Asked Questions (FAQs)
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Questions & answers or comments about how we can rule out certain areas as plausible locations for a septic tank, drainfield, drywell, cesspool, or soakaway bed by examining terrain features and location of a nearby well, stream or pond..
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
Percolation Testing Manual, CNMI Division of Environmental Quality, Gualo Rai, Saipan provides an excellent English Language manual guide for soil percolation testing. Original source: www.deq.gov.mp/artdoc/Sec6art108ID255.pdf
Soil Test Pit Preparation, fact sheet, Oregon DEQ Department of Environmental Quality, original source www.deq.state.or.us/wq/pubs/factsheets/onsite/testpitprep.pdf The Oregon DEQ onsite water quality program can be contacted at 811 South Ave, Portland OR 97204, 800-452-4011 or see http://www.oregon.gov/DEQ/
Thanks to reader Michael Roth
for technical link editing 6/29/09.
Septic Tank/Soil-Absorption Systems: How to Operate & Maintain [ copy on file as /septic/Septic_Operation_USDA.pdf ] - , Equipment Tips, U.S. Department of Agriculture, 8271 1302, 7100 Engineering, 2300 Recreation, September 1982, web search 08/28/2010, original source: http://www.fs.fed.us/t-d/pubs/pdfimage/82711302.pdf.
Pennsylvania State Fact Sheets relating to domestic wastewater treatment systems include
Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
Document Sources used for this web page include but are not limited to: Agricultural Fact Sheet #SW-161 "Septic Tank Pumping," by Paul D. Robillard and
Kelli S. Martin. Penn State College of Agriculture - Cooperative Extension, edited and annotated by
Dan Friedman (Thanks: to Bob Mackey for proofreading the original source material.
Advanced Onsite Wastewater Systems Technologies, Anish R. Jantrania, Mark A. Gross. Anish Jantrania, Ph.D., P.E., M.B.A., is a Consulting Engineer, in Mechanicsville VA, 804-550-0389 (2006). Outstanding technical reference especially on alternative septic system design alternatives. Written for designers and engineers, this book is not at all easy going for homeowners but is a text I recommend for professionals--DF.
Builder's Guide to Wells and Septic Systems, Woodson, R. Dodge: $ 24.95; MCGRAW HILL B; TP;
Quoting from Amazon's description: For the homebuilder, one mistake in estimating or installing wells and septic systems can cost thousands of dollars. This comprehensive guide filled with case studies can prevent that. Master plumber R. Dodge Woodson packs this reader-friendly guide with guidance and information, including details on new techniques and materials that can economize and expedite jobs and advice on how to avoid mistakes in both estimating and construction. Chapters cover virtually every aspect of wells and septic systems, including on-site evaluations; site limitations; bidding; soil studies, septic designs, and code-related issues; drilled and dug wells, gravel and pipe, chamber-type, and gravity septic systems; pump stations; common problems with well installation; and remedies for poor septic situations. Woodson also discusses ways to increase profits by avoiding cost overruns.
Country Plumbing: Living with a Septic System, Hartigan, Gerry: $ 9.95; ALAN C HOOD & TP;
Quoting an Amazon reviewer's comment, with which we agree--DF:This book is informative as far as it goes and might be most useful for someone with an older system. But it was written in the early 1980s. A lot has changed since then. In particular, the book doesn't cover any of the newer systems that are used more and more nowadays in some parts of the country -- sand mounds, aeration systems, lagoons, etc.
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