What Lies Beneath: A Practical Guide to Understanding Percolation Tests
For those who have built their homes, they know there are two ways to deal with wastewater and fluids. It’s either a municipal water treatment system or you build a septic tank to store the wastewater and clean it up more often. For the people who use the municipal water treatment facilities, it largely remains out of sight and hence out of mind. But for people who use the septic system, they must understand that how their soil and ground absorb water and waste is crucial. Soil has to be tested to determine whether it can absorb wastewater should the occasion arise. Percolation tests make such a determination of the soil’s absorption capacity.
What is a Percolation Test?
Percolation tests, or perc tests, determine how quickly the soil can absorb water or any liquid. Such tests are required to evaluate whether the soil is suitable for making a septic system or a drainage solution. In simple terms, it’s to figure out how fast water disappears into the soil. Perc tests are standard procedure in land development, construction, and sometimes adherence to the laws and regulations of the area. The absorption rate is expressed as the time (in minutes) taken for the water level in the soil to drop by one inch.
Firstly, the land was dug into small holes, 6 to 12 inches deep and 4 to 5 inches wide. The soil is presoaked in water to make it saturated, mimicking the conditions for a heavy downpour or waste discharge. Then the water is added and the measured how long it takes for the water level to drop one inch. The result is called the perc rate and measured as minutes per inch (mpi). Every soil types have different perc rates; for instance, sandy soil has a lower perc rate, which means it drains water faster. While clay soil has a perc rate higher than average, which means it drains soil more slowly.
The Science Behind the Soak: How It Works
Percolation is based on hydrology and soil science. Percolation is the downward movement of fluid or water through the soil due to gravity. Soil is a mixture of different materials such as sand, clay, silt, and organic matter. The porosity of the soil depends on the ratios of the different components. For instance, if the soil has more components of sand, it is more porous. Some of the factors affecting percolation rates are as follows:
Soil moisture: Soil percolation rate is dependent on soil moisture. If the soil is wet and saturated, the percolation would be low as existing water would stop the fluid from outside from penetrating the soil.
Soil structure: The arrangement of soil molecules also impacts the percolation rate. Porous soil with lots of empty spaces allows water to seep through, while more clustered soil will lead to low percolation.
Groundwater Table: The percolation ability of soil also depends on the groundwater levels. A high groundwater level prevents the soil from absorbing water. A lower groundwater level helps the water within the soil to penetrate and flow freely.
Soil compaction: Soil compaction is the process of soil particles being pressed together, reducing spaces and pores. Fewer pores means the soil won’t be able to absorb water as easily as soil particles with more pores. More compacted soil leads to slower percolation.
Why You Should Care Even If You’re Not a Contractor
Understanding the percolation test is beneficial even if you are not a contractor or managing a real estate project:
Buying Property: You need to know about the perc test if you are buying property in a place that does not have access to municipal water treatment. A failed perc test can vastly jeopardize the plumbing system of the house. It can be potentially expensive to repair or replace the septic system.
Gardening and Landscaping: If you are engaged with gardening and landscaping, understanding the perc test can help gauge whether the soil is suitable for growing plants. A perc test can determine if the soil allows sufficient absorption of water and nutrients for the plant to thrive.
Stormwater Management: The Perc test also helps in stormwater management. Understanding the soil absorption rate, you can understand how effective your drainage system is, especially during a storm. Based on the perc tests, contractors and developers can arrange to improve the drainage system to avoid any plumbing problems.
Common Myths and Misunderstandings
Myth: A perc test is a one-time thing.
Reality: Soil conditions change with time and weather conditions. It can also change with population changes, infrastructure changes, and construction. Therefore, perc needs to be conducted frequently. Perc tests can differ significantly from the original one as time goes by.
Myth: You can improve a failing perc test by adding sand.
Adding soil can impact the immediate vicinity of the soil during a perc test, but it does not impact the underlying soil composition. Improving the soil drainage system involves soil amendment measures and a change in the drainage system infrastructure.
Myth: All perc tests are the same.
Perc tests differ from location to location, depending mainly on local authorities, rules, and regulations. Variation can be seen from the size of the hole, presoaking procedures, additional technologies, and measurement units.
Myth: A perc test guarantees a septic system will work perfectly.
The perc test is only one aspect of a septic system. Other factors contribute to the functioning of a healthy septic system, such as installation, system design, and maintenance. A well-designed septic system can still fail even with a perfect perc score.
Conclusion
Percolation test is an effective method of testing the soil’s absorption capabilities, which is essential for building a septic system and forms an important part of real estate development. Perc test knowledge can be beneficial whether you are a homeowner or contractor. Perc helps you to fix and adjust your septic system and improves drainage quality. Follow the procedure for perc as per the rules and regulations for your area. Call trusted and certified experts for performing the perc and do not DIY this test as it can reveal manipulative results.
FAQs
Q: How much does a percolation test cost?
A perc test cost is measured by rate per hour. A standard rate can cost your $300 per hour with more challenging can fetch you even more expenses. The cost is also calculated based on the area of the land as well. Rates are at an average of $900 per acre of land.
Q: Who can perform a percolation test?
Percolation tests can only be performed by experts and licensed professionals. These people can include soil scientists, engineers and local contractors. Hiring unlicensed professionals can prove to be risky.
