Site Requirements, Design Criteria, & Construction Details for Gravelless Septic Systems InspectAPedia® -
Design manual for gravelless or no rock septic fields
No-rock or chamber septic drainfield site requirements
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This chapter discusses the site requirements, design criteria, and construction details of a gravelless or "no gravel" or "no rock" septic
drainfield systems, offering installation specifications. Drainfields, also called leach fields, absorption
beds, soil absorption systems, and leaching beds, perform the functions of septic effluent treatment and disposal
in onsite wastewater treatment systems, conventionally called "septic systems".
Typical gravelless septic systems use a plastic chamber,
a geotextile-wrapped pipe, or a polystyrene-wrapped pipe to distribute effluent into the soil. The necessary soil absorption area is provided
by the perforated surface of the gravelless septic system components (or by soil at the bottom of a chamber) themselves rather than by the gravel and
trench walls of a conventional septic drainfield.
Advanced septic treatment methods are discussed in separate chapters. 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. Technical review by industry experts has been performed and is ongoing - reviewers welcomed and are listed at "References."
This article is part of our series: Inspecting, Testing, & Maintaining Residential Septic Systems an online book on septic systems.
Site Requirements & Design Criteria for Gravelless Septic Absorption Systems
Site Requirements:
These systems shall be used on sites that have
been classified as having a design percolation rate of one to 45 minutes
per inch, and meet the vertical and horizontal separation distances in
Table 2 (of the New York State Standard - for example) shown in 75-A.4 Soil and site appraisal for Septic Systems.(2)
Chamber systems provided by Infiltrator Inc. (links below) have been approved for use in some states, including New York,
at perc rates up to 60 minutes/inch, and in some other states, at percs up to 120 minutes/inch. Approval letters are
available from that company.
Design criteria:
The local health department having jurisdiction shall be contacted prior to construction regarding the acceptability of
specific products for use as a gravelless distribution system. (3)
As we described above when discussing Geotextile-Wrapped Perforated Pipe systems for onsite wastewater treatment and
disposal, the total lot area in square feet which is required for a given alternative treatment system will vary not only
depending on the anticipated daily flow, flow rates, soil and site conditions, but also on what spacing requirements the local
or state code officials will require.
So although a number of alternative treatment systems including these gravelless
methods are capable of working in a smaller total square foot area than a conventional drain field, depending on what the
local authorities require in spacing, more area may be required than the minimum. For example, many states require that
space be set aside to allow for future absorption line replacement in between the planned lines.
Construction of gravelless septic absorption systems
Gravelless distribution systems shall be installed in
conformance with the manufacturer's instructions because of the
proprietary design of some products.(4) The length, width, and depth of the
required excavation will vary by individual product.
The essential difference between
a gravelless wastewater treatment system and a conventional perforated-pipe and gravel-trench drainfield
is the use of a special product to distribute and release effluent (sketches above) and the absence of
gravel in the trench where the distribution system is buried.
The special gravelless products used
are designed to avoid soil-clogging right at their surface or they would have a short life. This
concern is addressed by use of special materials (such as geotextiles) which resist soil clogging,
and by a design that provides an adequate total area in square feet for soil contact.
Each product manufacturer should be expected to provide an installation manual for the product
that you are going to use. The list below is generic and incomplete as site specific and product
specific details can't be provided here.
Perform a site survey to determine the size, layout, and materials needed. The manufacturer
indicate the disposal area provided by the product (per linear foot, for example) but your engineer
and installer need to evaluate your soils and daily wastewater usage to determine the amount
of leaching area needed for your site. (Tables of field sizing and soil percolation test
procedures are provided at this website).
Obtain local building code or board of health requirements
As with any wastewater disposal field, never drive equipment in or over the trenches. Compacting
the soil (or after installation, damaging the drainage components) will reduce the absorption
system capacity or may destroy it completely.
Some systems such as Infiltrator Inc. chambers,
have been tested to meet an H-10 engineering rating (16,000 lbs / axle), so occasionally if a
system built using some chamber products are driven over it won't necessarily be an issue. But
Infiltrator Inc. 's technical experts do not recommend constant vehicle traffic over anything but
their heavier duty H-20 chambers.
These disclaimers notwithstanding, it remains a better practice
to keep all traffic off of septic fields. And even where
septic equipment has been described as rated for vehicle traffic, heavy equipment
traffic can cause some surprising
collapses that can be costly to repair as shown in this photo.
Some sites may need a curtain drain or other special measures to redirect surface or subsurface
runoff away from the effluent/wastewater absorption area.
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Additional technical contributors & reference sources for this article are listed below.
Crumpler Plastic Pipe, Inc. Crumpler provides fabric-wrapped drainage piping 800-334-5071 Roseboro NC USA - "No-Rock TM Septic-Leachate drainpipe systems" are available in 8" and 10" systems.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
How Big Should the Leach Field Be? includes a practical example using sample calculations and a table of soil percolation rate vs. field size Design Basics for Septic Systems: Choosing Septic Tank Size, Leach Field Size - basic septic system volume and absorption system design guides. Components of a Septic System- the Basic Parts of a Conventional Septic Tank and Leachfield, a chapter in the Home Buyers Guide to Septic Systems Sketches of the Septic System Components Private Sewage Disposal Systems - Septic Drawing Library Cesspools for more in-depth information about those systems. DRYWELL DESIGN & USES for more in-depth information about those systems.] SEPTIC SYSTEM DESIGN ALTERNATIVES
(1) (2) (3) (4) APPENDIX 75-A to Public Health Law, 201(1)(1) NEW YORK STATE WASTEWATER TREATMENT
STANDARDS - INDIVIDUAL HOUSEHOLD SEPTIC SYSTEMS. Portions of
the text of this web page (using paragraphs identified by parenthetical numbers (1)-(4)) are quoted from this document,
expanded with edits and additions by this author
"Gravelless Drainfields, Recommended Standards and Guidance for Performance, Application, Design and Operation & Maintenance",
Washington State Department of Health, an MS Word .doc file available at: www.doh.wa.gov/ehp/ts/WW/Gravelless2004.doc
Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow, calculating required septic tank size, calculating septic tank volume from size measurements
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.)
...
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
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), Advanced Onsite Wastewater Systems Technologies.
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 we 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 Manua [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)
"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. 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.
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
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
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
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