Increasing population and development in the Table Rock Lake watershed threatens water

resources by increasing sources of nutrient pollution, not the least of which is failing septic

systems. The largely rural population uses onsite wastewater treatment systems (OWTS) to treat

wastewater, although these systems are often not suitable to the thin existing soils in the region

to effectively treat wastewater. The Table Rock Lake National Demonstration Project tested

different types of advanced technology for OWTS. The Demonstration Project also utilized the

Environmental Protection Agency’s (EPA) management models for proper maintenance of

OWTS. This project planned to find solutions to the many failing and inadequate OWTS in the

Table Rock Lake area. Three main goals were:

A number of excellent decentralized treatment technologies including advanced OWTS (systems

with pre-treatment components before dispersal into soil) had been field-tested elsewhere and

were commercially available. The focus of the Demonstration Project was to compare

technology and test performance in treating wastewater and phosphorus removal using FAST,

RetroFAST, ZABEL or ZABEL SCAT treatment systems in the Table Rock Lake area.

With advanced OWTS regular maintenance is needed to ensure proper functioning. Advanced

OWTS had received a bad reputation nationwide due to failures from lack of maintenance by

system owners. A responsible maintenance entity (RME) was needed to remove maintenance

responsibilities from real estate developers or homeowners.

In the past advanced OWTS technologies have not been widely accepted as feasible or practical

and most contractors in the area were unfamiliar with such systems. The few installers that had

experience with advanced OWTS, such as drip dispersal, did not generally recommend these

systems or install them due to maintenance concerns. With adoption of renewable operating

permits requiring maintenance, an answer to this concern would be presented.

Twenty five sites were installed or remediated through this Demonstration Project. Criteria for

acceptance into the project included environmental need, installation feasibility, cost share

potential and the owner’s willingness to cooperate with project goals. Different types of

advanced OWTS installed included constructed wetlands, aeration/fixed film, media filters using

foam cubes and peat moss and recirculating sand filters. All of these systems effectively pre-treat

wastewater before dispersal into surface stream or soil.

Monitoring systems were installed on four sites to measure treatment success. Samples were

taken from septic tank effluent (raw sewage), treatment effluent (pre-treated, filtered liquids) and

sub-surface liquids (after passing by drip irrigation through the soil). Analysis of samples

produced evidence of successful treatment with effluent BOD5 (biochemical oxygen demand)

and TSS (total suspended solids) values from three of the monitored systems consistently below

20 mg/L. The fourth monitored system was a much higher restaurant-strength waste, which had

median treatment BOD5 and TSS of 59 and 32 mg/L respectively. Median sub-surface

phosphorus concentrations ranged from 0.5 to 1.2 mg/L demonstrating the soil’s capacity for

phosphorus removal.

The major results from the Demonstration Project are:

Data from this project will provide regulatory agencies with scientific evidence necessary to

accept advanced OWTS as standard systems removing them from experimental status. Project

partners and participants gained applied knowledge of advanced OWTS and alternative treatment

technology to help protect water quality resources. Education and outreach through numerous

local, statewide and national meetings helped to focus attention on the potential water quality

implications of failing wastewater systems and successful remediation systems in the Table Rock

Lake watershed. An outstanding benefit of the Demonstration Project includes a change in the

way OWTS are installed in southwest Missouri, along with a change in the public’s perception of

advanced OWTS. Another applied achievement of the project was the formation of OCWC

which will continue to grow and provide service to benefit residents of Missouri particularly

residents of the Table Rock Lake watershed. This project may serve as a national action model

for other lake communities facing similar problems and needing effective solutions.