Soak pit is an important component of the overall sanitary unit of a building. It may be defined as a closed porous chamber that is connected to the primary treatment unit of a residential as well as a commercial building that permits the passage of wastewater through it.
In other words, it allows the wastewater collected from the septic tank of the building to soak into the underlying ground. It is also referred to as soak way or leach pit.
Soak pit is a relatively efficient construction that allows the infiltration of wastewater collected from a septic tank or even a certain type of latrine deep into
the ground when the wastewater is not intended for reuse. It is a commonly used
technique of discharging wastewater and also helps in recharge of groundwater.
As the wastewater penetrates the ground, smaller particles get filtered by the matrix of the soil itself while the organic waste present in the wastewater are decomposed and digested by the micro-organisms present in the soil. On account of this, leach pit is most suitable at places where the soil is highly porous. A well-constructed soak pit can last for a period of 3 to 5 years.
NEEDS OF SOAK PIT
The wastewater is also known as greywater that is obtained from the primary treatment unit of building such as septic tank, settler, twin-pit latrine etc is impure and thus cannot be allowed to percolate directly into the ground. A certain degree of treatment must be provided to the collected wastewater before it is allowed to settle. For such partial treatment, a soak pit is generally provided. The wastewater infiltrated from the soak pit can be used for recharge of groundwater.
DESIGN OF SOAK PIT
1. The design of a typical soak pit generally consists of a pit of approximately 1 cubic meter with a depth of 1.5m to 4m.
2. It must not be constructed nearby a drinking water source as it can pose contamination of the drinking water source.
3. It must be constructed at least 30m away from such a source.
4. It can be provided with a lining of porous material for additional support.
5. It must be noted that the soak pit is not constructed in an area subjected to the high volume of traffic as it may cause compaction of the pit.
6. A thin layer of sand and gravel may be provided at the bottom of the pit to disperse the flow of wastewater.
7. A lid preferably concrete lid must be constructed to cover the soak pit.
FUNCTIONS OF SOAK PIT
1. It serves the function of a receiver and collects the wastewater from the primary treatment unit.
2. It allows the collected wastewater to get purified to some extent.
3. It thus allows non-harmful water to infiltrate into the ground.
4. It thereby helps in the recharge of groundwater.
ADVANTAGES OF SOAK PIT
1. It is a relatively simple and easy technique.
2. The construction is simple and locally available materials can be used for its
3. It requires only a small area.
4. The initial cost, as well as the operation cost, is affordable.
5. It helps in the recharge of groundwater bodies.
DIS-ADVANTAGES OF SOAK PIT
1. It is applicable only in areas where the soil is porous and allows percolation
2. It is not suitable for highly congested areas.
3. There is a high risk of clogging in the absence of primary treatment.
4. It is not suitable for cold climatic conditions.