Septic Systems

This year’s National SepticSmart Week is September 18-22, 2017. The Environmental Protection Agency (EPA) uses a week in September each year to focus on improved awareness of proper operation and maintenance of septic systems across the United States. The wastewater of approximately 25 percent of the population of the United States is treated by on-site or individual wastewater systems. In Nebraska, this statistic holds consistent with 25 percent of our state’s population being served by onsite wastewater systems on farms, acreages, suburbs and even some small communities.

Pump tank regularly. Have a professional inspect and pump the tank. Conserve water and spread usage over a period of time. Manage solids. Keep hazardous materials out. Let the system work naturally. Avoid drainfield compaction. Avoid introducing excess water to the drainfield. Maintain structural integrity of the drainfield.

Anaerobic bacteria begin to break down some wastes in the tank. Wastewater contains suspended solids. Heavy solids settle out and form sludge on the bottom of the tank.

A system typically has 3 parts: plumbing from the house, a septic tank, and an effluent treatment system.

The effluent is distributed through the pipes/gravel or chambers, then percolates down into the soil. Oxygen is present and aerobic bacteria break down the waste. Viruses are held by soil particles and die over time.

A septic tank must be watertight. The wastewater has not been fully treated, so it must be contained and prevented from escaping into the environment. Septic tanks can be made of concrete, concrete blocks, fiber-reinforced plastic, high-density plastic or fiberglass.

Problems sometimes occur. Some of the problems that occur include: sluggish drainage, contaminated drinking water, wastewater surfacing in the yard, odors, and pipes freezing.

An important soil characteristic, the percolation rate, measures how long it takes water to drop one inch in a saturated hole dug in soil. Fast: 1 inch in 3 minutes (sandy soil). Slow: 1 inch in 48 minutes (clay soil). If it takes less than 5 minutes for the water to drop 1 inch in a saturated hole, the effluent will move too rapidly to be treated properly, such as in sandy soil.

The ability of soil to accept water or for water to travel through soil is called soil permeability. Percolation is the movement of water through soil. A soil percolation test is designed to measure the rate of water movement in saturated soil (mimicking conditions that soil treatment systems have) so that one can decide the appropriate type and size of treatment system.