Steep slope septic drainfield systems. This article describes the installation of septic drainfields or leach lines on difficult terrain such as on steep slopes where a property disposes of wastewater using a septic tank and drainfield.
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Guide to Septic Installations on Steep Slopes
Also see Sewer or Septic Line Installation at Steep Sites, and for people conducting a septic system inspection or test, also see DIFFICULT SEPTIC SITES. Technical reviewers are welcome and are listed at "References." Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. Use of this information at other websites, in books or pamphlets for sale is reserved
to the author.
Our photo (left) illustrates terracing used by the excavator during a septic drainfield installation. In addition to the text of this article (below), readers concerned with septic installation advice for steeply sloped or rolling sites should see these articles:
- Sewer or Septic Line Installation at Steep Sites which describes sewer piping between a building and septic tank or sewer main at steep sloped sites which slope down significantly between the building and the septic tank.
- DOSING SYSTEMS PRESSURE which describes pressure dosing systems that may be useful for disposing of septic effluent at steep sites where the drainfield must be located either uphill or downhill from a septic tank or building.
- GRAVELLESS SEPTIC SYSTEMS- some gravelless systems can handle gentle curves necessary to follow rolling slope lines
- Pumps Septic pumps, sewage ejector pumps, grinder pumps, effluent pumps, sump pumps, & septic pumping stations, septic pump alarms - systems that will be needed if a building or septic tank are lower than the drainfield or sewer main.
- STEEP SLOPE DESIGNS (text located just below) which describes installation of septic drainfields on steep or rolling sites.
Guide to Installing Steep Slope Septic Drainfield Systems
Installing Septic Drainfield Piping on Steep Slopes Located Downhill from the Septic Tank - Uniformly Sloped Land
The sketch at page top shows an installation approach for septic drainfields across a steep or rolling slope.
- D-box for septics on steep slopes: Clarified septic effluent leaves the septic tank (or an effluent pumping station) and flows into a large distribution box. This D-box will need to be larger and have more connecting ports than those used for a conventional flat-area drainfield: each effluent line to be located across the hillside needs to connect directly to the D-box.
- Individual effluent lines for steep slope septics: Connected to the distribution box are individual septic effluent drain lines, each of which is routed to an individual gravel trench and perforated drainfield
- Effluent line feeder pipes for steep slope septic systems: Piping between the distribution box and the drainfield trench is solid, not perforated.
- Effluent lines for hillside or rolling land drainfields: Each of the drainfield lines is installed along the slope, not uphill or downhill, sloping gently (1/8" to 1/4" per linear foot) from the inlet end of each drainfield trench to its lowest point.
Installing Septic Drainfield Piping on Steep Slopes Located Downhill from the Septic Tank - Rolling Land
- Flexible distribution piping or gravelless systems for steep slope septics: Where land is rolling or contoured, flexible piping may be easier to install than rigid pipe systems since flexible effluent lines can be routed in a trench which needs to curve in order to remain parallel to the fall line of the slope of rounded hilltops or rolling land.
- Pressure dosing for steep slope septic systems: Other septic effluent handling systems such as pressure distribution systems may be more tolerant of installation on steep or uneven sloped land and can employ either rigid or flexible perforated piping.
- Drip lines which also use flexible distribution piping for septic system effluent dispersal may also work on some hilly sites.
Why Drainfield Effluent lines need to be properly sloped
Septic drainfields that treat and dispose of clarified wastewater effluent using gravity need to be properly pitched and never sloped too steeply. Otherwise effluent will run too quickly to the low end of the drainfield line and gravel trench where it is likely to simply break out to the property surface.
If you have to install a conventional perforated pipe and gravel trench drainfield on a steep slope you'll need to run the trenches along the slope or parallel to the fall line, stepping down the slope from trench to trench.
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Technical Reviewers & References
Publisher's Google+ Page by Daniel Friedman
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
- Inspecting Septic Systems: Online Book, Inspection, Test, Diagnosis, Repair, & Maintenance: our Online Septic Book: Septic Testing, Loading & Dye Tests, Septic Tank Pumping, Clearances, details of onsite waste disposal system inspection, testing, repair procedures.
- 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.
Design Manuals for Septic Systems
US EPA Onsite Wastewater Treatment Systems Manual [online copy, free] Top Reference: US EPA's Design Manual for Onsite Wastewater Treatment and Disposal, 1980, available from the US EPA, the US GPO Superintendent of Documents (Pueblo CO), and from the National Small Flows Clearinghouse. Original source http://www.epa.gov/ORD/NRMRL/Pubs/625R00008/625R00008.htm Onsite wastewater treatment and disposal systems,
Richard J Otis, published by the US EPA. Although it's more than 20 years old, this book remains a useful reference for septic system designers.
U.S. Environmental Protection Agency, Office of Water Program Operations; Office of Research and Development, Municipal Environmental Research Laboratory; (1980)
- Eco John® Innovative Toilet Solutions, Global Inventive Industries, Fountain Valley CA, PDF, product brochure
- "International Private Sewage Disposal Code," 1995, BOCA-708-799-2300, ICBO-310-699-0541, SBCCI 205-591-1853, available from those code associations.
- "Manual of Policy, Procedures, and Guidelines for Onsite Sewage Systems," Ontario Reg. 374/81, Part VII of the Environmental
Protection Act (Canada), ISBN 0-7743-7303-2, Ministry of the Environment,135 St. Clair Ave. West, Toronto Ontario M4V 1P5 Canada $24. CDN.
- Manual of Septic Tank Practice, US Public Health Service's 1959.
Onsite Wastewater Disposal Books
- Onsite Wastewater Disposal, R. J. Perkins;
Quoting from Amazon: This practical book, co-published with the National Environmental Health Association,
describes the step-by-step procedures needed to avoid common pitfalls in septic system technology.
Valuable in matching the septic system to the site-specific conditions, this useful book will help you install a reliable system in
both suitable and difficult environments. Septic tank installers, planners, state and local regulators, civil and sanitary engineers,
consulting engineers, architects, homeowners, academics, and land developers will find this publication valuable.
- Onsite Wastewater Treatment Systems, Bennette D. Burks, Mary Margaret Minnis, Hogarth House 1994 - one of the best septic system books around, suffering a bit from small fonts and a weak index. (DF volunteers to serve as indexer if Burks/Minnis re-publish this very useful volume.)While it contains some material more technical than needed by homeowners, Burks/Minnis book on onsite wastewater treatment systems a very useful reference
for both property owners and septic system designers. We refer to it often.
While Minnis says the best place to buy this book is at Amazon (our link at left), you can also see this book at Minnis' website at http://web page .pace.edu/MMinnisbook
- 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
- Soil Percolation Tests soil perc testing guide and instructions
- Percolation Testing Manual, CNMI Division of Environmental Quality, PO Box 501304, Saipan, MP 96950
- Planting Over Septic System Component", Daniel Friedman (author/editor, InspectAPedia.com), The Innovator, Winter/Spring 2008, BCOSSA, British Columbia OnSite Sewage Association, 201-3542 Blansard St., Victoria BC V8X 1W3 Canada
- Save the Septic System - Do Not Flush These Items Down the Toilet, Daniel Friedman, InspectAPedia.com - PDF document, printable
- SEPTIC STANDARDS
- SEPTIC MAGAZINES
- Septic System Owner's Manual, Lloyd Kahn, Blair Allen, Julie Jones, Shelter Publications, 2000 $14.95 U.S. - easy to understand, well illustrated, one of the best practical references around on septic design basics including some advanced systems; a little short on safety and maintenance. Both new and used (low priced copies are available, and we think the authors are working on an updated edition--DF.
Quoting from one of several Amazon reviews: The basics of septic systems, from underground systems and failures to what the owner can do to promote and maintain a healthy system, is revealed in an excellent guide essential for any who reside on a septic system. Rural residents receive a primer on not only the basics; but how to conduct period inspections and what to do when things go wrong. History also figures into the fine coverage.
- Test Pit Preparation for Onsite Sewage Evaluations, State of Oregon Department of Environmental Quality, Portland OR, 800 452-4011. PDF document. We recommend this excellent document that offers detail about soil perc tests, deep hole tests, safety, and septic design. Readers should also see Soil Percolation Tests and for testing an existing septic system, also see Dye Tests
- Grass is Always Greener Over the Septic Tank, Bombeck, Erma: $ 5.99; FAWCETT; MM;
This septic system classic whose title helps avoid intimidating readers new to septic systems, is available new or used at very low prices.
It's more entertainment than a serious "how to" book on septic systems design, maintenance, or repair. Not recommended -- DF.
- US EPA Onsite Wastewater Treatment Systems Manual Top Reference: US EPA's Design Manual for Onsite Wastewater Treatment and Disposal, 1980, available from the US EPA, the US GPO Superintendent of Documents (Pueblo CO), and from the National Small Flows Clearinghouse. Original source http://www.epa.gov/ORD/NRMRL/Pubs/625R00008/625R00008.htm
- Water Wells and Septic Systems Handbook, R. Dodge Woodson. This book is in the upper price range, but is worth the cost for serious septic installers and designers.
Quoting Amazon: Each year, thousands upon thousands of Americans install water wells and septic systems on their properties. But with a maze of codes governing their use along with a host of design requirements that ensure their functionality where can someone turn for comprehensive, one-stop guidance? Enter the Water Wells and Septic Systems Handbook from McGraw-Hill.
Written in language any property owner can understand yet detailed enough for professionals and technical students this easy-to-use volume delivers the latest techniques and code requirements for designing, building, rehabilitating, and maintaining private water wells and septic systems. Bolstered by a wealth of informative charts, tables, and illustrations, this book delivers:
* Current construction, maintenance, and repair methods
* New International Private Sewage Disposal Code
* Up-to-date standards from the American Water Works Association
- Wells and Septic Systems, Alth, Max and Charlet, Rev. by S. Blackwell Duncan, $ 18.95; Tab Books 1992. We have found this text very useful for conventional well and septic systems design and maintenance --DF.
Quoting an Amazon description:Here's all the information you need to build a well or septic system yourself - and save a lot of time, money, and frustration. S. Blackwell Duncan has thoroughly revised and updated this second edition of Wells and Septic Systems to conform to current codes and requirements. He also has expanded this national bestseller to include new material on well and septic installation, water storage and distribution, water treatment, ecological considerations, and septic systems for problem building sites.
- The NSFC Products List has an excellent list of design manuals/modules available from their website or by telephone 800-624-8301
- Submissions welcome. send us a suggested document link or request an exchange of website links