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rolls. They design, construct, operate, and maintain such facilities to meet Virginia wastewater treat^ ment performance requirements. They involve people who have been trained, tested, and certified or licensed, and who monitor the performance of the system. Centralized systems cost big bucks. The homeowner or business pays a significant “connection” or “tap” fee to hook up to them. Customers also pay a monthly or quarterly usage fee. Onsite/Decentralized Versus Centralized
Wastewater
Treatment
Now we come to the second kind of wastewater treatment facility, the “onsite/ decentralized” systems. The basic form is the traditional septic tank and its drainage field, handling about 300 gallons of wastewater per day.
It is a passive system, no moving parts. It just sits there underground, doing its thing. Flush the toilet and the stuff does not travel miles away via sewer pipes to be treated. Everything happens in your backyard, including the dispersal of the effluent.
Usually, liquid from the septic tank drains downward into your property via an underground drainage system, to seep through the soil, called an absorption field, to be cleansed. All that is called primary treatment.
But over the last 25 years there has been a movement to add secondary, even tertiary, treatment capabilities to some septic tanks. They make use of units with a mix of pumps, filters, alarms, stirrers, drip or spray units, disinfection units, chemicals, etc. Called alternative or innovative , treatment devices, their purpose is to further cleanse effluent.
These units can be used for the remediation of failed or failing septic systems. EPA estimates that between
95.6%