A septic system has a limited lifespan, similar to other major home systems. Over time, the soil in the drain field (previously called leach field) develops a biological buildup called biomat, which reduces its ability to absorb wastewater and can eventually cause system failure.
Before a reputable installer can provide an accurate estimate for a septic system installation or system replacement, an engineered design with proper field sizing must be completed. The process is similar to building a new home, a contractor must first have blueprints before preparing a reliable estimate.
A new or replacement Onsite Wastewater Treatment System (OWTS) typically includes a new Soil Treatment Area (STA) and, a new septic tank (for replacement systems, a new tank may not be required). Several factors can affect the overall cost, including property location, existing landscaping, soil conditions, setback requirements, existing utilities, and the size and type of system required.
In addition to continual regulation updates, this often means that a replacement OWTS may differ significantly from the original or existing system.
It is nearly impossible to provide an accurate estimate until a licensed soils engineering firm completes a soil evaluation in the proposed location of the new or updated STA. This evaluation generally includes two test holes excavated approximately eight feet deep using a backhoe.
During the evaluation, engineers analyze and classify the soil as sand, clay, sandy clay, sandstone, claystone, or bedrock. The soil classification, along with the total number of bedrooms in the home — not bathrooms — is used to properly design and size the new or replacement septic system.
