New York State Septic System Design Regulations 75-A.4 - Soil and site evaluation for septic system design InspectAPedia® -
Specification for soil testing to evaluate land for septic system installation
Soil percolation tests perc tests perk tests for septic systems
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Soil Percolation Tests or Perc Tests: Section 4 of the septic design regulations discusses the procedure for evaluating site and soil conditions in preparation
for the design of a private septic system to handle onsite wastewater disposal. For the installation of a conventional
septic tank and leach field, minimum useable soil depth, percolation rates, leach field clearance distances,
and the requirement for a future repair or expansion area are reviewed, and a table of separation distances
from septic components to other site and building features is provided.
This document uses the New York State wastewater treatment standard for individual household septic systems
(Appendix 75-A) to provide an example of state regulated design and installation of both conventional
tank and leach field septic systems and alternative septic system
designs, including raised septic systems, septic mound systems, intermittent sand filter septic systems,
and evaportion-transpiration septic systems. Readers needing to know more about soil percolation tests or who want to see other examples of soil perc test specifications should also see Perc Tests: Soil Percolation & Soil Depth Requirements for Septic Absorption Systems / Septic Drainfields
Also see SEPTIC CODES & REFERENCES and SEPTIC CONSULTANTS. 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."
Effective Date: 12/01/90
Title: Appendix 75-A.4 - Soil and site appraisal
(a) Site Investigation.
(1) Areas lower than the 10 year flood level are unacceptable for
on-site systems. Slopes greater than 15% are also unacceptable.
(2) There must be at least four feet of useable soil available above
rock, unsuitable soil, and high seasonal groundwater for the
installation of a conventional absorption field system (75-A.8(b)).
(3) Soils with very rapid percolation rates (faster than one minute per
inch) are not suitable for subsurface absorption systems unless the site
is modified by blending with a less permeable soil to reduce the
infiltration rate throughout the area to be used.
(4) Subsurface treatment systems and components of the sewage system
shall be separated from buildings, property lines, utilities and wells,
to maintain system performance, permit repairs and reduce undesirable
effects of underground sewage flow and dispersion. The minimum
separation distances are shown in Figures 1 and 2. Reduced separation
distances may be approved upon request when the site evaluation by a
design professional or soil scientist clearly establishes there will be
no adverse environmental impact and will not interfere with the
satisfactory operation and maintenance of the system. Table 2 shows the
acceptable minimum separation distances from the various components of
treatment systems.
(5) Once the required infiltration area is determined by daily flow,
percolation tests and soil evaluation, the required useable area of the
property for subsurface treatment can be found. An additional useable
area of 50 percent shall be set aside for future expansion or
replacement whenever possible.
(b) Separation Requirements for septic system components from buildings and other site features:
TABLE 2 - SEPARATION DISTANCES FROM WASTEWATER SYSTEM COMPONENTS
TO STREAM, LAKE
WELL OR WATERCOURSE (b) PROPERTY
SYSTEM COMPONENTS SUCTION LINE OR WETLAND DWELLING LINE
House sewer 25'if cast iron 25' 10' 10'
(watertight joints) pipe
50'otherwise
Septic tank 50' 50' 10' 10'
Effluent line to
distribution box 50' 50' 10' 10'
Distribution box 100' 100' 20' 10'
Absorption field 100' (b) 100' 20' 10'
Seepage pit 150' (b) 100' 20' 10'
Dry well
(roof and footing) 50' 25' 20' 10'
Raised or
Mound system 100' 100' 20' 10'
Evapotranspiration-
absorption system 100' 50' 20' 10'
Composter 50' 50' 20' 10'
NOTES to the table
(a) When sewage treatment systems are located in coarse gravel or
upgrade and in the general path of drainage to a well, the closest part
of the treatment system shall be at least 200 feet away from the well.
(1) The highest groundwater level shall be
determined and shall include the depth to the seasonal high groundwater
level and the type of water table -- perched, apparent, or artesian.
(2) If a subsurface treatment unit such as an absorption field is
planned, at least four feet of useable soil shall be available over
impermeable deposits (i.e., clay or bedrock). Highest groundwater level
shall be at least two feet below the proposed trench bottom. Where
systems are to be installed above drinking water aquifers, a greater
separation distance to bedrock may be required by the local health
department having jurisdiction.
At least one test hole at least six feet deep shall be dug within or
immediately adjacent to the proposed leaching area to insure that
uniform soil and site conditions prevail. If observations reveal
differing soil profiles, additional holes shall be dug and tested.
These additional holes shall be spaced to indicate whether there is a
sufficient area of useable soil to install the system.
Treatment systems shall be designed to reflect the most severe
conditions encountered. If the percolation tests results are
inconsistent with field determined soil conditions, additional
percolation tests must be conducted and the more restrictive tests must
be the factor used for the system design.
(3) Specifications for soil percolation septic test holes: Test holes for seepage pits shall extend to at least mid-depth and
full depth of the proposed pit bottom. At least three feet of useable
soil shall exist between the pit bottom and rock or other impermeable
soil layer and the highest groundwater level. This shall be confirmed
by extending at least one deep test hole three feet below the deepest
proposed pit.
(4) Alternatives to soil percolation tests: A local health department may accept or require other soil tests in
lieu of the percolation test when such tests are conducted or observed
by local health department personnel.
(d) Soil Percolation Test Detailed Specifications
(1) At least two percolation tests shall be
made at the site of each proposed sewage treatment system.
(2) For seepage pits, one test shall be conducted at the bottom depth,
and the other at half the pit depth. If different soil layers are
encountered when digging the test pit, a percolation test shall be
performed in each layer with the overall percolation rate being the
weighted average of each test based upon the depth of each layer. The
local health department having jurisdiction may adopt an alternative
procedure for determining the permeability of soil for the installation
of seepage pits.
(3) A percolation test is only an indicator of soil permeability and
must be consistent with the soil classification of the site as
determined from the test holes.
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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.
AEROBIC SEPTIC SYSTEMS
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. (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
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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