Wastewater Subsurface
Drip Distribution

Research Project

Drip Distribution Dosed with Septic Tank Effluent versus Secondary Quality Effluent

Overview

The project will include a pair of identical drip dispersal systems that will share the same location and wastewater supply. One system will apply septic tank effluent and the second will apply water that has been treated to secondary water quality standards. Each system will consist of a control system (with appropriate filtration), dose tank and approximately 1000 feet of drip tubing. Before installation, the emitters will be checked for uniformity, and the soil will be analyzed to determine the saturated hydraulic conductivity and any redoximorphic features will be documented. Wastewater will be applied at the design rate. The major parameters that will be analyzed are BOD, COD, TOC, nitrogenous compounds, and total Phosphorous.

The major benefit of the research will be the determination as to whether secondary treatment is needed before wastewater is applied to the soil by a drip dispersal system. By not having to invest in advanced treatment technologies, the cost of building new homes and businesses in economically depressed areas will be reduced. A secondary benefit is a better understanding of the benefits and problems of using drip irrigation techniques to apply wastewater to the soil. The lessons learned during this project will be addressed during training sessions sponsored by the CDWM.

Project Update

The project is now underway. A site has been selected for the installation of the two drip dispersal systems. The Consolidated Utility District is allowing the installation of the two drip systems in a subdivision located near Murfreesboro, TN. The subdivision is using a recirculating sand filter and a drip dispersal field to treat and dispose of its wastewater.

The site has been surveyed and is awaiting a soil survey. The next step will include installing a weather station at the site and to utilize ground penetration radar (GPR) technology to conduct an initial survey of the subsurface.

The CDWM staff is currently in the laboratory measuring the uniformity of the emitters that will be installed at the site. Once the project has begun, on a monthly basis, a small segment of dripperline will be removed and replaced. The emitters will be taken back to the laboratory and evaluated for any reduction in emission rate.