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Onsite Sewage Research Projects

IntroductionOngoing Research ProjectsUpcoming Research ProjectsPast Research Projects


The research program has many current and upcoming projects looking at how onsite sewage treatment and disposal systems impact public health and the environment.

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Ongoing Research Projects

The research program is currently working on the research projects listed below.

Florida Water Management Inventory (2015 – Ongoing)

An inventory of Onsite Sewage Treatment and Disposal Systems (OSTDS) is a needed first step to develop appropriate onsite wastewater management strategies. There is a strong interest in having an OSTDS inventory that includes all onsite systems in Florida described at parcel level that provides important information about each system and the location of these systems. This information is critical for disaster response activities, water resource management, wastewater treatment planning, human health protection and for other projects for which this dataset can be employed. A snapshot OSTDS inventory was completed in 2009 in response to a Legislative request. The original inventory had many unknown/estimated status of wastewater treatment methods for parcels and large data gap. The new inventory program – named Florida Water Management Inventory (FLWMI) started in 2015 and has since gone through three phases. The goal of the project is to provide an up-to-date centralized geographic data map linking each built property in the state with a drinking water source (public water or private domestic well) and wastewater treatment method (central sewer or onsite septic).

Continued Monitoring on Passive Nitrogen-Reducing Onsite Sewage Treatment and Disposal Systems (OSTDS) (2017 - Ongoing)

The Florida Onsite Sewage Nitrogen Reduction Strategy (FOSNRS) study conducted in 2009-2015 identified the passive nitrogen-reducing media systems as one of the most cost-effective systems for nitrogen control. Seven full-scale systems were constructed during 2012-2013, and monitored on a quarterly basis for almost two years (2013 through 2014). Results from the study demonstrated that passive nitrogen-reducing media systems can remove approximately 65% to more than 95% of the nitrogen in wastewater with limited maintenance efforts and low operating costs.

In early 2017, the department resumed monitoring on four remaining FOSNRS systems to evaluate their long-term performance as they become mature. Based on results from eight quarterly sampling events, more than six years after these systems were constructed, the systems continue to remove an average of more than 80% of the nitrogen in wastewater. The maintenance efforts and operating costs remained low. Department staff is planning to replace the denitrification media of one system and evaluate the improvement on the nitrogen-reducing efficiency. Some results from the monitoring can be found in a presentation given to the department’s Research Review and Advisory Committee (RRAC). A draft final report for the study has been prepared.

Development of Funding Mechanisms for OSTDS Remediation and Upgrade (2018 – Ongoing)

Each year, more than 15,000 OSTDS owners apply for repair permits to fix their malfunctioning OSTDS. The actual number of failed OSTDS can be significantly larger than this number. One factor that causes the delay of repair to failed systems is the lack of proper funding assistance. This project investigated possible funding sources in Florida and, specifically, focused on the mechanism that other states use to manage and distribute the Clean Water State Revolving Fund (CWSRF) loan to assist the repair, replacement, and upgrade of onsite wastewater systems. Department staff is preparing a report to summarize the findings from the investigation. Some results from the investigation can be found in a presentation given to the Research Review and Advisory Committee (RRAC).

Upcoming Research Projects

Two additional projects were prioritized by the Research Review and Advisory Committee (RRAC) in late 2017.

Correlation between Water Quality, OSTDS, and Health Effect

The goal of this project is to evaluate possible spatial and temporal relationships between regional distribution of OSTDS and their potential human health and environmental health effects, using geographic information system (GIS), statistical analyses approach and case studies. Using the regional spatial and temporal data sets to evaluate the impact of OSTDS on the water quality and human health condition can avoid the uncertainties associated with the site-specific studies and laboratory studies on the environmental and human health impacts from OSTDS, and provide more realistic and practical information on water resource and human health management.

Estimation of Failure or non-conformance rates of OSTDS

One approach to evaluate OSTDS environmental impact is to determine the frequency of OSTDS not functioning properly. Frequency of OSTDS “failure” is often used and determined by multiplying the frequency of repair permits by a number of years before the “failure” is identified. The accuracy of this approach has never been tested. In addition, failure is not the only way that a malfunctioning onsite system can impact the environment. Other non-compliance issues with OSTDS may also cause significant environmental concerns. The goal of this study is to collect and evaluate data from several OSTDS inspection programs, identify the type of OSTDS rule non-conformance and evaluate the frequency of the non-conformance. The information from the study will provide water resource manager with basic information to evaluate impacts from OSTDS. Data being collected and preliminary data analyses so far can be found in a presentation given to the Research Review and Advisory Committee (RRAC)

Last Modified:
September 21, 2022 - 9:27am

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