Bedford County advisory committee reviews decentralized "step" wastewater systems and agrees to draft local standards

The Bedford County Wastewater Advisory Committee on March 12 heard detailed presentations about decentralized "step" wastewater systems — technologies that use on-site pre-treatment, pressurized collection lines, recirculating-media treatment trains and drip-field effluent dispersal — and agreed to develop local rules for the planning commission to review.

Mark Lee, a consultant who helped develop early step-system guidance, described the systems’ four components and said they can allow higher lot yield where soils are suitable. "We call them step systems because of the septic tank and it's got an effluent pump in there," Lee said, explaining that designers begin by mapping usable soils with NRCS surveys and a registered soil scientist to size drip fields and determine lot yield.

The presenters emphasized conservative design assumptions. Lee and Matt Nicks of Edge Wastewater said residential design flow is set at 300 gallons per day (gpd) per lot, a number they called conservative compared with measured community averages. "Historically you're looking at 165 to 175 gallons a day of flow on average across a community," Lee said, a point Matt Nicks reiterated when discussing rental housing: "We're doing a rental community ... we're going to increase that" to allow for…