Onsite Wastewater Treatment Within The Shallow Soil Horizon

By Dennis F. Hallahan, P.E.

In the world of environmental engineering wastewater treatment, the name of the game is surface area. The more surface area provided, the more bugs (microbes) will inhabit the surface and consume waste. There are many complex, highly advanced mechanical devices designed to optimize surface area. With onsite wastewater systems, the answer (unlimited surface area) is right under our feet — literally. Regardless of its composition, soil is one of nature's most sophisticated purification tools. The soil can provide highly advanced, efficient treatment to purify water that then allows it to resupply and replenish groundwater and aquifer supplies, perpetuating the hydrologic cycle.

Decentralized wastewater treatment continues to evolve as scientists, engineers, regulators, and product manufacturers work to create system designs and applications that protect our fragile environment while responding to the call for sustainable, cost effective development. Homeowners, builders, and developers searching for reasonable land need wastewater treatment options that perform well under a variety of often less than ideal conditions. Even as land costs have lowered in many areas, easy-to-develop land in urban and suburban metro areas is in short supply and sewer hookups are often not readily available or cost effective. In addition, new technologies for onsite wastewater treatment are necessary to satisfy the desire to build in areas where there is limited or no centralized treatment available.

New systems are only part of the story. Regulation requiring system upgrades and the increasing number of systems needing repair are pushing the search for manufacturers that offer not only products but also alternative, cost-effective installation solutions.