A soil test is performed to determine the size, location and type (conventional or mound) of wastewater treatment system that will be installed at your home. After viewing the property and discussing the homeowner’s needs, the soil tester typically digs three to five holes with a backhoe to view and handle the soils to determine the soil’s drainage capability, the average high groundwater mark and signs of bedrock.
The characteristics of the soil determine what type of septic system is needed to treat domestic wastewater. When a septic system disperses household waste water or effluent into the ground it must be three feet above the limiting factor. 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 quantity, size, contrast and color of the mottles give an indication of how often and how long water is present. Bedrock is a limiting factor because it either prevents effluent from dispersing into the ground or allows it to get into ground water before treating it. The structure and texture determine how well the soil will drain. If the soil is impermeable you will create a pond of sewage in your yard. Loose soils do not allow adequate time for treatment to take place.
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 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.
After the soil test, the tester will fill out a Soil and Site Evaluation Report. The report includes the site map and describes the characteristics of the soil and 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 county or agency which regulates septic systems.