Soil test pits or soil mantles are excavations done with a backhoe to verify effective soil depth. Effective soil is considered soil that will treat or filter sewage. For a standard sewage disposal system (in our counties) a minimum 6 feet of effective soil is required, 4 feet of effective soil below the trench bottom. The standard trench depth is 24-inches.
Percolation test are used to determine how fast or slow water will filter through the soil. A perc hole is dug to the anticipated trench bottom or to the limiting horizon. The hole is pre-soaked to simulate winter time or wet weather conditions. Readings of how quickly water leaves this hole are taken the following day. These reading are then averaged to calculate your average percolation rate.
For more informaiton about Perc & Mantles, visit our Perc & Mantles Services Page.