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SINKHOLES, WARNING SIGNS
SOAKAWAY BED FAILURE DIAGNOSIS
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TOILETS, INSPECT, INSTALL, REPAIR
TRAPS on PLUMBING FIXTURES
TREATMENTS & CHEMICALS, SEPTIC
VIDEO GUIDES: Septic Videos
WASHING MACHINES & SEPTIC SYSTEMS
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This article provides a master list (links at Related Topics ) of all alternative septic system designs for difficult building sites such as wet sites, steep sites, rocky sites, limited space, bad soils with no percolation or sandy soils with too fast percolation, sites close to a lake, river or stream, and other difficult site conditions. We provide detailed articles about each alternative septic system design choice, listing its features, design requirements, inspection details, maintenance needs, product sources. We include links to septic design engineers, advanced septic system products and septic design books and building codes. This document is a chapter provides in our Septic Systems Online Book.
Examples of advanced septic designs discussed in this article series include aerobic septic systems, chemical, composting, incinerating & waterless toilets, evaporation-transpiration (ET) septic systems, septic media filters, greywater systems, holding tank septic systems, mound septics, peat filter septics, raised bed septics, pressure dosing septic systems, sand bed filters, peat beds, constructed wetlands, wastewater lagoons, constructed wetlands, and septic disinfection systems.
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Consultants in this field can be listed at our alternative septic designers page at no charge by contacting me. Also see The Septic System Information Website. Technical reviewers welcomed and are listed at Reviewers.
This article describes just about every type of alternative septic system design and provides links to detailed descriptions of these designs for onsite wastewater treatment. "Septic System Alternative Designs" refers to any onsite wastewater disposal method other than the widely used conventional septic tank and leach field. In the U.S. most states require that an "alternative septic system" be designed by a professional and submitted to the local health department for approval.
Alternative onsite wastewater disposal systems can reduce the soil absorption area or leach field size requirement substantially and can in fact in some cases reduce the needed area to zero. For problem sites where space or soil conditions make it difficult to install a conventional leach field or where an existing septic system has failed, these designs are very important alternatives.
The alternative septic system designer conducts the site and soil inspection and testing, prepares the system design and installation plan, supervises the septic system construction, and certifies that the system was installed as designed.
Alternative septic system designs are used for new or replacement septic systems on difficult sites where soil conditions (such as a rocky site, limited soil percolation rate, or high ground water level), or other terrain conditions (such as limited space for a septic system or steeply sloped sites) do not permit the installation of a conventional septic tank and drainfield system.
Examples of site conditions that lead to consideration of an alternative septic design include:
Because various texts provide so many different views of categorizing wastewater systems, I've made this simple list which groups wastewater treatment systems into a few major categories: [Readers should see our Master List of Septic System Types or our list of alternative septic system designs and products in the links at the left of these pages.]
Our Master List of Septic System and Wastewater Treatment Alternative Designs below offers a complete list of alternative septic system designs and major septic system component designs along with a description of each septic system/onsite wastewater treatment approach. For each system we link to articles providing more in-depth design, installation, repair, inspection, maintenance and product source information.
In case the above list of wastewater treatment categories is not enough, there are also various levels of degree of treatment of septic effluent achieved by different versions of these systems, by natural wetlands septic systems, or by use of septic effluent disinfection systems. For example, you may read about more than one type of gravity dosing or pressure-dosing sand filter beds system which look a lot alike but which achieve different degrees of effluent treatment.
Jantrania (see Alternative Septic Designers) describes eleven Onsite Wastewater Treatment Types in a confusing list (Table 1.3 in his text) since the same type of system may appear more than once (drainfields) depending on the level of treatment achieved by a specific implementation. In the same text the author proposes a Pollution Scale numbered from 0 Drinking Water) to 10 (Sewage). (p.36). An overall sewage treatment level of 50% would be 5.0 on this scale, and a treatment level of 100% would mean that the output of the system was equivalent to drinking water in purity.
Because over time the concentration of contaminants in incoming sewage and wastewater varies by type of use, level of building occupancy, changing soil moisture and temperature, and other factors, it is risky to assume that a regulation or a septic system design level requiring or claiming 90% treatment (pollution scale 1.0) is always producing effluent treated to exactly that level.
Awareness of the variation in level of contaminants in sewage arriving at a treatment system, as well as awareness of variations in site conditions (level of ground water, temperature, frequency of inspection and maintenance) is behind the very conservative standards adopted by many health departments regulating septic system installations.
The terms percentage of treatment and level of treatment of sewage or wastewater are used in different and perhaps confusing ways. A writer may say that "45% of the effluent treatment occurs in the septic tank".
I take this to mean that whatever the overall or final level of wastewater treatment that the whole system is going to provide, from input to the system to final discharge of effluent into the environment, 45% of it is occurring inside the septic tank. This does not necessarily mean that the effluent discharged from the septic tank is 45% of the way along the pollution scale or nearly half way to being pure drinking water.
The term "level of treatment" should be reserved to mean the overall or final degree of purity of the effluent which is discharged to the environment.
Sewage contaminants- what's in sewage, and typical sewage contaminant levels are discussed in more detail at Septic system contaminants.
Adding to the complexity of what to call various septic systems, there are also categories of methods of septic effluent dispersal (to the final treatment and soil absorption or other effluent disposal system) such as:
An individual septic system design may use a combination of these methods to treat, disperse, and dispose of septic effluent. For example, a sand filter bed septic system might be fed by gravity, by a gravity-operated dosing system, or by a pump operated pressure dosing system.
Keeping these types of of septic systems (treatment methods) and these types of wastewater dispersal systems (disposal methods) in mind when reviewing various off-the-shelf packaged septic systems or wastewater treatment systems with interesting but non-descriptive names (like the "magic bullet treatment box") will help you to understand the general approach which has been taken in any specific case and will help you choose among alternative septic system designs and products.
Further reading will be needed to understand the installation cost, maintenance cost, and level of management required of each type of septic system. I collect and publish here additional details on alternative septic system design, installation costs, and maintenance costs.
Links at the left of this page and most of our septic information website pages offer descriptions, design suggestions, product sources for each of these septic system types.
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Frequently Asked Questions (FAQs)
I was interested in a piece of property which I understand that cannot accommodate sumping. I am under the impression (because I have not gotten to the end of figuring out why just yet) that this is because it is a waterfront property and/or the water table is too close to the surface thus reducing the availability of sufficient drainfield without causing water contamination. So my question is; is there another approved alternative to the absorption field to effectively control liquid effluent retention? - D.M. 8/29/2013
From your email I think you need an onsite septic design engineer - there sounds like a confusion of terms, codes, and requirements, and in my own case I'm not sure what you mean by "sumping" nor "liquid effluent retention" - those terms are not ones I use for onsite wastewater disposal.
If you are asking about a holding tank (sewage is retained and periodically pumped and removed by a waste hauler) some communities permit that design along a waterway but many do not.
If you are asking about how sewage and (separated) effluent are handled at wet sites, there are some designs that can handle that case, sometimes combining treatment above ground with disinfection; but again, not all communities will approve them.
That's why you need an onsite expert who also knows local codes & officials.
Some options you might want to discuss can be found in the article link I give just below. Also take a look at Anish Jantrania's book listed in the references section of that article. Dr. Jantrania has described wastewater treatment systems that can function effectively entirely above ground, producing sanitary wastewater discharge.
Questions & answers or comments about septic system design specifications & solutions for difficult sites
Ask a Question or Enter Search Terms in the InspectApedia search box just below.
Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
Septic System Types & Onsite Wastewater Treatment Alternative Designs
Each of the links below presents a document with more in-depth information about each of these alternative septic system designs.
Design Manuals for Septic Systems
Onsite Wastewater Disposal Books