Soil Testing & Design
What is soil testing and when do I need it?
Before purchasing a vacant property, you should complete a soil test to determine what type of system can be installed. A soil test and sanitary permit must be on file with the county before a building permit can be issued.
A soil test is also required when replacing an existing septic system where an alternate site has not been previously determined.
Soil tests are needed to determine what type of septic system, also known as wastewater treatment system (POWTS), is required for a residence or business. The soil test tells us the type of septic system (conventional or mound), the size and location. Wisconsin law states that a certified soil tester (CST) must perform this test. Before any soil testing is done, we discuss the needs of the property owner. Then, after viewing the property and discussing the homeowner's needs our soil tester will typically dig what is called soil pits into the ground. The pits allow the soil tester to identify the characteristics of the soil and determinee the soil's drainage capability, the average high groundwater mark and any signs of bedrock.
The characteristics; structure, type of soil and high ground water features, determine how well the soil will drain. The characteristics also will determine what type of septic system is needed to treat domestic wastewater derived from ordinary living conditions such as toilets, sinks, dishwashers, laundry, etc. When a septic system disperses household waste water or effluent into the ground it must be three feet above the limiting factor. Loose soils do not allow adequate time for treatment to take place. And if the soil is impermeable you will create a pond of sewage in your yard. If an in-ground system can not get three feet of separation, an at-grade or mound is installed. Mottling, bedrock, structure and texture are all limiting factors.
Mottling or mottles are colors in soil caused by the presence of water in soil. The tester will look for irregular coloring in the soil (mottling) which are the result of chemical reactions in the soil as the seasonal water table rises and falls. A determination of the highest point at which mottling is observed will estimate the property's high groundwater level.
The soil tester documents the horizons or different layers of the soil. The tester analyzes the consistence, the type of boundary between the horizons and the size and quantity of the roots in the soil. A site map is also made during the soil test. The map shows where the pits or borings are on the property, the location of the current structures or proposed structures, the well, the slope of the tested area and the legal description of the lot. All this information is needed to determine the type and location of your system.
Then, after the soil test, the tester will fill out a Soil and Site Evaluation Report. The report includes the site map and a detailed description of the soils. This report also has the information needed for a septic system installer to design the system and to pull the necessary permits. The tester then submits the report to the agency which regulates septic systems in the county in which the property is located.