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Sand filter septic design details: this document discusses design and use of septic media filters using sand. When using a septic media filter system, effluent treatment is by both actual filtration and ultimately by a biochemical process as the
filter "matures" and includes its own biomass. This is particularly true of sand-bed filter septic systems which also
often use a recirculating sand bed design to move septic effluent multiple passes through the sand filter system.
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Septic Media Filters Using Sand
The septic tank which receives
waste from the building should have either two compartments, or two tanks in series are used.
A gas baffle on the tank outlet
is recommended (NY State Wastewater Treatment Standards) to reduce the chances of a periodic bolus of gas
forming in the bottom of the tank and forcing solids into the sand media.
When a sand filter system is used, effluent is periodically distributed out of the septic tank and
over the surface of a constructed
bed of sand through a network of perforated pipes. Collector pipes below the sand pick up effluent after it
has filtered through and been treated by (the biomat formed on) the sand filter.
Effluent dosing is by pressure-fed perforated lines of 1.5" to 3" diameter, or by siphon dosing
using a 3" to 4" diameter effluent line. New York requires that the system is dosed at least three times
daily. Dosing should not exceed 1.15 gallons/day/sq. ft. of media area.
Various texts cite the critical importance of selecting the proper sand for a septic media filter. New York's standard
specifies a sand grain size of 0.25 to 1.0 mm; if nitrification is required (which may be specified by
the local health department), the grain size is larger, 0.5mm to 1.0 mm., and all sand is passed through
a 1/4" sieve and must be uniform to a coefficient of 4.0.
The effluent collector pipes below the sand bed discharge the treated effluent to an absorption system
such as a drain field placed below the original ground level or possibly into a raised bed or mound system.
The raised bed or mound receiving the treated effluent may itself be constructed of sand or other
fill material with a percolation rate of not faster than 5 minutes per inch.
Typical sand filter construction (NY State Wastewater Standards) involves an excavated bed area which is filled
in layers of material as follows (bottom up):
- Collector pipe system set in gravel sized 3/4" to 1.5" aggregate.
- 4" of aggregate above the collector pipes
- 3" of crushed stone or clean gravel sized 1/8 to 1/4" atop the aggregate.
- 24" of approved sand. Jantrania points out that a geotextile fabric should not be placed
below the sand and atop the gravel. Though some installers think that's a great idea to keep the
sand out of the gravel, he points out that the fabric is likely to clog and lead to early
sand filter bed failure.
- Distribution pipes placed in a layer of aggregate providing 4" or more across the whole surface
of the sand filter and with aggregate of at least 2" underneath and above the distribution pipes.
- A geotextile, 2" of hay or straw, or untreated building paper is placed atop the bed to keep
soil fines out of the filter.
- 6" to 12" of topsoil is placed atop the sand filter bed system, mounded to encourage surface water
runoff to drain off of the system. The topsoil is seeded to grass.
Sand filter problems: keep deep rooting plants, surface runoff, and heavy traffic (that could
compact the media) off of the system. Don't block air movement over the surface of the system with
buildings or plantings.
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Technical Reviewers & References
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More Reading on Sand Filter Systems
Using a Sand Bed Effluent Disposal System as a Component of Alternative Septic Systems for Difficult Sites.
This document includes the NYS Appendix 75-A section on sand filter beds (next citation) as well as sand filter bed
design comments and advice from other experts
SAND FILTER SEPTIC DESIGN SPECIFICATIONS -
New York State Appendix 75-A Design Details for Intermittent Sand Bed Filter Septic Systems
References for this Septic Media Filters Discussion
- Measuring Septic Sludge & Scum Levels in Septic Tanks - Measuring the Level of Accumulated Solids, Sludge and Floating Scum in Treatment Tanks
- Septic Contaminants, identifying - what are the Nitrogen contaminants produced by septic systems and what can be done about them if they escape initial treatment?
- Safety: Septic System, Septic Tank, & Cesspool Safety Warnings for Septic Inspectors, Septic Pumpers, and Homeowners
- Sewage & Septic Backups and what to do about sewage spillage in buildings
- SEPTIC SYSTEM FLOOD DAMAGE REPAIR when and what to do to a septic system after area flooding
- "Septic Tank/Drainfield System Fact Sheet", Utah Department of Environmental Quality, Division of Drinking Water, Source Protection Program - (801) 536-4200 Division of Water Quality - (801) 538-6146 Sonja Wallace, Pollution Prevention Coordinator - (801) 536-4477 Environmental Hotline - 1-800-458-0145 - Original source: http://www.drinkingwater.utah.gov/documents/spec_services/pollution_prevention_septic_tanks.pdf
- New York State Wastewater Treatment Standards - Individual Household Systems, Appendix 75-A (1990),
Public Health Law 201(1)(1).
- New York State Alternative Septic System Design Regulations, Wastewater Treatment Standards - Individual Household Systems, Appendix 75-A, of Public Health Law 201(1)(1) 1990.
- Advanced Onsite Wastewater Systems Technologies, Anish R. Jantrania, Mark A. Gross, CRC Taylor & Francis, 2006 ISBN 0-8493-3029-7
order a copy from the InspectAPedia bookstore (Amazon.com)
- Anish Jantrania, Ph.D., P.E., M.B.A., Consulting Engineer, Mechanicsville VA, 804-550-0389
- The Septic System Owners's Manual, Lloyd Kahn, Blair Allen, Julie Jones, Shelter Publications, 2000. ISBN 0-936070-20-X - order a copy from the InspectAPedia bookstore (Amazon.com)
- Onsite wastewater
treatment systems, Bennette D. Burks & Mary Margaret Minnis. Textbook and reference manual on all aspects of onsite treatment. This is one of the best books we've reviewed on the subject, with an excellent balance of clear simple explanation and solid engineering. Topics: Soil & Site Selection, Hydraulics, System Selection & Design, Wastewater Biology, History & Mythology of Onsite Wastewater
Treatment. $49.95, Hogarth House, Ltd., 800-993-2665 x327 order a copy from the InspectApedia bookstore (Amazon.com) or order by telephone 800 -993-2665 x327 (Univ. Wisc. Bookstore)
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. 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
- 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