LCRA used an evaluation matrix that incorporates the volume of wastewater, soils, the distance from systems to waters, the number of system failures, and the age of the systems, to rank the risk of failure of various on-site systems in the region and the likelihood that they could be remedied with new and innovative technologies. Blessing was ranked 11th out of 16 sites that were reviewed, signifying that there were opportunities to develop a demonstration site there. System Design and Construction Both constructed wetlands in Blessing have a similar design. An effluent meter on each pump line measures the volume of wastewater being generated. Primary treatment is provided by a septic tank.
Effluents flow from the septic tank to the first of two wetlands cells that are operated in series.
Each cell is 5' wide x 2' deep x 20' long. A small berm surrounds each cell to prevent rainfall runoff from entering the wetlands. The system was designed to operate mainly under gravity flow conditions. The only pumping that is required is to lift effluents from the septic tank into the first cell because of the lack of slope at the sites. Following treatment in the wetlands cells, effluents are routed to two drainfields.