This definition appears very rarely
See other definitions of PSND
Samples in periodicals archive:
In both of these options, effluent continues to be treated as it is dispersed to the native soil. Because effluent from advanced treatment technologies contains very small amounts of solids and organic matter (food for bacteria), it is best introduced to the soil environment in the most biologically active, near-surface soils (tope soil) of a site, where existing soil microbes can further reduce pathogen counts and nutrient loads. Plants rooted in these shallow soils also help to remove nutrients from the effluent before it moves downward through the soils toward the water table. When dispersed into deeper, less active zones of the soil, there may not be enough organic matter (solids) in the effluent to sustain the beneficial bacterial community, and further treatment may not occur to the extent achieved in shallow dispersal. In Rhode Island, approved final dispersal technologies include pressurized shallow narrow drainfields.
Recirculating Sand Filter and Single Pass Sand Filter guidance relating to design, installation and O&M is available in this document. For the new Pressurized Shallow-Narrow Drainfield.