Difference between revisions of "Soak Pit"

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{|style="float: left;"
<!-- table at top of page with logo, picture, Application level, Management level, and input-output tables -->
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|{{Language-box|english_link=Soak_Pit|french_link=Puisard|spanish_link=Pozo_de_Absorción|hindi_link=coming soon|malayalam_link=coming soon|tamil_link=coming soon | korean_link=coming soon | chinese_link=Coming soon | indonesian_link=Coming soon | japanese_link=Coming soon}}
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{|width="100%"
 
{|width="100%"
 
|style="width:50%;"|{{santable_new|
 
|style="width:50%;"|{{santable_new|
 
sys1=[[Single Pit System|1]]|
 
sys1=[[Single Pit System|1]]|
 
sys2=[[Waterless System with Alternating Pits|2]]|
 
sys2=[[Waterless System with Alternating Pits|2]]|
sys3=[[Pour Flush System with Twin Pits|3]]|
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sys3=[[Pour Flush Pit System without Sludge Production|3]]|
 
sys4=[[Waterless System with Urine Diversion|4]]|
 
sys4=[[Waterless System with Urine Diversion|4]]|
sys5=[[Blackwater Treatment System with Infiltration|5]]|
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sys5=[[Biogas System|5]]|
 
sys6=|
 
sys6=|
 
sys7=|
 
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ManShared=XX|
 
ManShared=XX|
 
ManPublic=|
 
ManPublic=|
Input1=Effluent |Input2=Greywater |Input3=Urine | Input4= Anal Cleansing Water|Input5=|
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Input1=Effluent |Input2=Greywater |Input3=Urine | Input4= Anal Cleansing Water|Input5=Stored Urine|
Output1=- |Output2= | Output3= | Output4= | Output5=
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Output1=Stored Urine |Output2=Anal Cleansing Water | Output3= | Output4= | Output5=
|english_link=Soak_Pit
 
|french_link=Puisard
 
|spanish_link=Pozo_de_Absorción
 
 
}}
 
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|[[Image:Soak-pit.png |right|300px]]
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[[Image:Icon_soak_pit.png |right|80px]]
 
[[Image:Icon_soak_pit.png |right|80px]]
'''A Soak Pit, also known as a soakaway or leach pit, is a covered, porous-walled chamber that allows water to slowly soak into the ground. Pre-settled effluent from a Collection and Storage/Treatment or (Semi-) Centralized Treatment technology is discharged to the underground chamber from where it infiltrates into the surrounding soil.'''
+
 
 +
'''A soak pit, also known as a soakaway or leach pit, is a covered, porous-walled chamber that allows water to slowly soak into the ground. Pre-settled effluent from a Collection and Storage/Treatment or (Semi-) Centralized Treatment technology is discharged to the underground chamber from which it infiltrates into the surrounding soil.'''
  
 
<br>
 
<br>
The Soak Pit can be left empty and lined with a porous material (to provide support and prevent collapse), or left unlined and filled with coarse rocks and gravel. The rocks and gravel will prevent the walls from collapsing, but will still provide adequate space for the wastewater. In both cases, a layer of sand and fine gravel should be spread across the bottom to help disperse the flow. The soak pit should be between 1.5 and 4m deep, but never less than 1.5m above the ground water table.
+
As wastewater (greywater or blackwater after primary treatment) percolates through the soil from the soak pit, small particles are filtered out by the soil matrix and organics are digested by microorganisms. Thus, soak pits are best suited for soil with good absorptive properties; clay, hard packed or rocky soil is not appropriate.
  
As wastewater (pre-treated greywater or blackwater) percolates through the soil from the Soak Pit, small particles are filtered out by the soil matrix and organics are digested by micro-organisms. Thus, Soak Pits are best suited to soils with good absorptive properties; clay, hard packed or rocky soils are not appropriate.
+
===Design Considerations===
 +
The soak pit should be between 1.5 and 4 m deep, but as a rule of thumb, never less than 2 m above the groundwater table. It should be located at a safe distance from a drinking water source (ideally more than 30 m). The soak pit should be kept
 +
away from high-traffic areas so that the soil above and around it is not compacted. It can be left empty and lined with a porous material to provide support and prevent collapse, or left unlined and filled with coarse rocks and gravel. The rocks and gravel will prevent the walls from collapsing, but will still provide adequate space for the wastewater. In both cases, a layer of sand and fine gravel should be spread across the bottom to help disperse the flow. To allow for future access, a removable (preferably concrete) lid should be used to seal the pit until it needs to be maintained.
  
 
<br>
 
<br>
 
{{procontable | pro=
 
{{procontable | pro=
- Can be built and repaired with locally available materials. <br> - Small land area required. <br> - Low capital cost; low operating cost. <br> - Can be built and maintained with locally available materials. <br> - Simple technique for all users. | con=
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- Can be built and repaired with locally available materials <br>
- Pretreatment is required to prevent clogging, although eventual clogging is inevitable. <br> - May negatively affect soil and groundwater properties.
+
- Technique simple to apply for all users <br>
 +
- Small land area required <br>
 +
- Low capital and operating costs
 +
| con=
 +
- Primary treatment is required to prevent clogging <br>
 +
- May negatively affect soil and groundwater properties
 
}}
 
}}
  
===Adequacy===
+
<br>
A Soak Pit does not provide adequate treatment for raw wastewater and the pit will clog quickly. A Soak Pit should be used for discharging presettled blackwater or greywater. Soak pits are appropriate for rural and peri-urban settlements. They depend on soil with a sufficient absorptive capacity. They are not appropriate for areas that are prone to flooding or have high groundwater tables.
+
===Appropriateness===  
 +
A soak pit does not provide adequate treatment for raw wastewater and the pit will quickly clog. It should be used for discharging pre-settled blackwater or greywater. Soak pits are appropriate for rural and peri-urban settlements. They depend on soil with a sufficient absorptive capacity. They are not appropriate for areas prone to flooding or that have high groundwater tables.
  
===Health Aspects/Acceptance===
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===Health Aspects/Acceptance===  
As long as the Soak Pit is not used for raw sewage, and as long as the previous Collection and Storage/Treatment technology is functioning well, health concerns are minimal. The technology is located underground and thus, humans and animals should have no contact with the effluent. It is important however, that the Soak Pit is located a safe distance from a drinking water source (ideally 30m). Since the Soak Pit is odourless and not visible, it should be accepted by even the most sensitive communities.
+
As long as the soak pit is not used for raw sewage, and as long as the previous Collection and Storage/Treatment technology is functioning well, health concerns are minimal. The technology is located underground and, thus, humans and
 +
animals should have no contact with the effluent.Since the soak pit is odourless and not visible, it should be accepted by even the most sensitive communities.
  
===Maintenance===
+
===Operation & Maintenance===  
A well-sized Soak Pit should last between 3 and 5 years without maintenance. To extend the life of a Soak Pit, care should be taken to ensure that the effluent has been clarified and/or filtered well to prevent excessive build up of solids. The Soak Pit should be kept away from high-traffic areas so that the soil above and around it is not compacted. When the performance of the Soak Pit deteriorates, the material inside the soak pit can be excavated and refilled. To allow for future access, a removable (preferably concrete) lid should be used to seal the pit until it needs to be maintained.
+
A well-sized soak pit should last between 3 and 5 years without maintenance. To extend the life of a soak pit, care should be taken to ensure that the effluent has been clarified and/ or filtered to prevent the excessive build-up of solids. Particles and biomass will eventually clog the pit and it will need to be cleaned or moved. When the performance of the soak pit deteriorates, the material inside the soak pit can be excavated and refilled.
 
 
Particles and biomass will eventually clog the pit and it will need to be cleaned or moved.
 
  
 
===Field experiences===
 
===Field experiences===
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===References===
 
===References===
* Ahrens, B. (2005). [http://cee.eng.usf.edu/peacecorps/5%20-%20Resources/Theses/Sanitation/2005Ahrens.pdf A Comparison of Wash Area and Soak Pit Construction: The Changing Nature of Urban, Rural, and Peri-Urban Linkages in Sikasso, Mali]. Peace Corp, USA. Detailed construction instructions.
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* Ahrens, B. (2005). [https://www.mtu.edu/peacecorps/programs/civil/pdfs/brooke-ahrens-thesis-final.pdf A Comparison of Wash Area and Soak Pit Construction: The Changing Nature of Urban, Rural, and Peri-Urban Linkages in Sikasso, Mali]. Peace Corps, US. (Detailed construction instructions)
 +
 
 +
* Mara, D. D. (1996). Low-Cost Urban Sanitation. Wiley, Chichester, UK. pp. 63-65. (Book; Dimensioning calculations)
  
* Mara, DD. (1996). [http://books.google.com/books/about/Low_cost_urban_sanitation.html?id=WOgeAQAAIAAJ Low-Cost Urban Sanitation]. Wiley, Chichester, UK. pp 63–65. Dimensioning calculations.
+
* Oxfam (2008). [https://policy-practice.oxfam.org/resources/septic-tank-guidelines-126711/ Septic Tank Guidelines]. Technical Brief. Oxfam GB, Oxford, UK. p. 4.
  
* Polprasert, C. and Rajput, VS. (1982). [http://docs.watsan.net/Scanned_PDF_Files/Class_Code_3_Sanitation/323.2-82SE-884.pdf Environmental Sanitation Reviews: Septic Tank and Septic Systems]. Environmental Sanitation Information Center, AIT, Bangkok, Thailand. pp 31–58.
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* Polprasert, C. and Rajput, V. S. (1982). [https://www.susana.org/en/knowledge-hub/resources-and-publications/library/details/2995 Environmental Sanitation Reviews. Septic Tank and Septic Systems]. Environmental Sanitation Information Center, AIT, Bangkok, TH. pp. 31-58.
  
 
===Acknowledgements===
 
===Acknowledgements===
 
{{:Acknowledgements Sanitation}}
 
{{:Acknowledgements Sanitation}}

Latest revision as of 03:46, 25 April 2021

English Français Español भारत മലയാളം தமிழ் 한국어 中國 Indonesia Japanese
Applicable in systems:
1, 2 , 3 , 4 , 5
Level of Application
Household XX
Neighbourhood X
City

 

Inputs
Effluent, Greywater, Urine, Anal Cleansing Water, Stored Urine


Level of management
Household XX
Shared XX
Public

 

Outputs
Stored Urine, Anal Cleansing Water
Soak-pit.png




Icon soak pit.png

A soak pit, also known as a soakaway or leach pit, is a covered, porous-walled chamber that allows water to slowly soak into the ground. Pre-settled effluent from a Collection and Storage/Treatment or (Semi-) Centralized Treatment technology is discharged to the underground chamber from which it infiltrates into the surrounding soil.


As wastewater (greywater or blackwater after primary treatment) percolates through the soil from the soak pit, small particles are filtered out by the soil matrix and organics are digested by microorganisms. Thus, soak pits are best suited for soil with good absorptive properties; clay, hard packed or rocky soil is not appropriate.

Design Considerations

The soak pit should be between 1.5 and 4 m deep, but as a rule of thumb, never less than 2 m above the groundwater table. It should be located at a safe distance from a drinking water source (ideally more than 30 m). The soak pit should be kept away from high-traffic areas so that the soil above and around it is not compacted. It can be left empty and lined with a porous material to provide support and prevent collapse, or left unlined and filled with coarse rocks and gravel. The rocks and gravel will prevent the walls from collapsing, but will still provide adequate space for the wastewater. In both cases, a layer of sand and fine gravel should be spread across the bottom to help disperse the flow. To allow for future access, a removable (preferably concrete) lid should be used to seal the pit until it needs to be maintained.


Advantages Disadvantages/limitations
- Can be built and repaired with locally available materials

- Technique simple to apply for all users
- Small land area required
- Low capital and operating costs

- Primary treatment is required to prevent clogging

- May negatively affect soil and groundwater properties



Appropriateness

A soak pit does not provide adequate treatment for raw wastewater and the pit will quickly clog. It should be used for discharging pre-settled blackwater or greywater. Soak pits are appropriate for rural and peri-urban settlements. They depend on soil with a sufficient absorptive capacity. They are not appropriate for areas prone to flooding or that have high groundwater tables.

Health Aspects/Acceptance

As long as the soak pit is not used for raw sewage, and as long as the previous Collection and Storage/Treatment technology is functioning well, health concerns are minimal. The technology is located underground and, thus, humans and animals should have no contact with the effluent.Since the soak pit is odourless and not visible, it should be accepted by even the most sensitive communities.

Operation & Maintenance

A well-sized soak pit should last between 3 and 5 years without maintenance. To extend the life of a soak pit, care should be taken to ensure that the effluent has been clarified and/ or filtered to prevent the excessive build-up of solids. Particles and biomass will eventually clog the pit and it will need to be cleaned or moved. When the performance of the soak pit deteriorates, the material inside the soak pit can be excavated and refilled.

Field experiences

The following project(s) utilize soak pits.

Akvorsr logo lite.png
RSR Project 644
Rwenzori Integrated School WASH Project


References

  • Mara, D. D. (1996). Low-Cost Urban Sanitation. Wiley, Chichester, UK. pp. 63-65. (Book; Dimensioning calculations)

Acknowledgements

Eawag compendium cover.png

The material on this page was adapted from:

Elizabeth Tilley, Lukas Ulrich, Christoph Lüthi, Philippe Reymond and Christian Zurbrügg (2014). Compendium of Sanitation Systems and Technologies, published by Sandec, the Department of Water and Sanitation in Developing Countries of Eawag, the Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.

The 2nd edition publication is available in English. French and Spanish are yet to come.