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The 2008 Legislature appropriated $1.0 million for Phase 1 of an
anticipated 3-5 year project to develop passive nitrogen
reduction for onsite sewage treatment and disposal systems
(OSTDS). The 2010 Legislature appropriated $2.0 million
for Phase 2 of the study. The 2012 Legislature appropriated
$1.5 million to fund the first part of Phase 3 of the project.
The original 2008 legislative
direction identified three areas of concern: (1)
Quantification of life-cycle costs and cost-effectiveness of
passive nitrogen reduction treatment technologies in comparison
to more active technologies and to convention treatment systems;
(2) Characterization of nitrogen removal from effluent in the
soil underneath the drainfield and in shallow groundwater;
and (3) Development of simple models to describe the fate and
transport of nitrogen from onsite sewage treatment and disposal
systems. The study contract was awarded on January 2009 to
a Project Team led by Hazen and Sawyer, P.C., and was based upon
an anticipated budget of $5 million over a 3-5 year project
status report was submitted to the legislature and the governor on February 1, 2013. Additional
funding has been requested for fiscal year 2013-2014.
As of February 2013 the contractor, in coordination with the RRAC and DOH, has successfully completed parts of
Tasks A, B, C, and D, including literature reviews; ranking of nitrogen reduction technologies for field testing;
design and construction of a test facility for further development of passive technologies; development of quality
assurance documents for the test facility work, groundwater monitoring, field testing, and nitrogen fate and
transport modeling; installation of nitrogen reducing systems at two home sites; completion of several sampling
events of passive systems at the test facility and field sites; design and construction of a soil and groundwater
test facility; and field sampling of the soil and groundwater under OSTDS at residential homes throughout Florida
and at the test facility.
Current efforts and work remaining for the 2012-2013 fiscal year includes: system installation and field sampling
at additional home sites throughout Florida for the testing of passive systems and to test the soil and groundwater
under OSTDS; sampling at the soil and groundwater test facility; and continuing with development of a nitrogen fate
and transport model. RRAC supports concluding this study as originally scoped.
To adequately fund the final phase of the project, $700,000 cash is required to fund the completion of scheduled tasks.
Further testing and analysis is required to confirm the results to date with field data and to provide data for
development of the engineering specifications for full system designs. The funds will be used to complete monitoring
and other field activities, perform additional testing as deemed appropriate by the Legislature, and for final
reporting with recommendations on onsite sewage nitrogen reduction strategies for Florida’s future.
Specific progress for this fiscal year, by task, is as follows:
The technology evaluation included a total of 7 sample events at the passive nitrogen test facility, measuring 14
different analytes at over 40 sampling points in 11 systems, as well as a final report on the pilot passive nitrogen
removal study at the Gulf Coast Research and Education Center (GCREC).
Current Status as of December 2012: All sample events at the test facility have been completed.
Test results are encouraging after 12 months of testing, showing a reduction in total nitrogen of over 95%, with a
final effluent concentration of 2.6 mg/L or less for several of the systems. Analysis of the results from the 11
systems and report writing is underway. Two additional, drainfield-based systems have been installed and have had
three monitoring events.
For field testing of technologies, the quality assurance project plan has been finalized. The research design
proposes that seven onsite systems, utilizing various nitrogen removal technologies, will be installed at home
locations throughout the State of Florida. It is anticipated that a total of seven field system performance
monitoring events will be conducted on each these systems with the current funding level, measuring 16 different
analytes at 2-8 different sampling points. A report providing a technical description of nitrogen reduction
technologies will be written, as well as a report providing a template and user guidelines for system life cycle
Current Status as of December 2012: Eleven homeowners residing at locations across Florida have
agreed to participate in the study to date for Task B. Home sites have been identified in Wakulla County, the
Wekiva area, and several other areas throughout the State. At least one of the home sites will have a gravity-fed
system installed. Construction has been completed for two systems. Six out of seven sample events have been
completed for the first system and one sample event has been completed on the second system. The design work has
begun for the next three systems, which are located in Seminole County.
To evaluate nitrogen reduction provided by soils and shallow groundwater, a soil and groundwater test facility
has been constructed to show how groundwater fate and transport of nitrogen occurs in multiple soil treatment unit
regimes. Six of the thirteen total sampling events will be completed with the current funding level, sampling three
of the four sites, and sampling six different locations at each site, and measuring multiple parameters in the
effluent, soil, and groundwater. The existing OSTDS mound system at the University of Florida’s Gulf Coast Research
& Education Center (GCREC) in Wimauma, Florida was instrumented to study how nitrogen behaves in the soil and
groundwater. Four sampling events that examine multiple parameters have been completed at the existing OSTDS mound
system at GCREC. At least three soil and groundwater monitoring events will occur at up to three home sites to
evaluate nitrogen movement in the soil and groundwater in the field, measuring multiple parameters in the effluent,
soil, and groundwater.
Current Status as of December 2012: Tasks that have been completed thus far are the testing of
media components per 381.0065(4)(m) F.S., two tracer tests to determine existing groundwater flow characteristics,
and construction of the soil and groundwater test facility. Three of six monitoring events have been completed at
four groundwater test areas at the soil and groundwater test facility to show how groundwater fate and transport of
nitrogen occurs. Instrumentation of the existing OSTDS mound system at GCREC has been completed and four sample
events have been conducted. Six homeowners have agreed to participate in the study to date for Task C. Four home
sites have been selected and instrumented. One sample event has occurred at the first of these sites, however, the
groundwater flow direction could not be delineated, and no additional sampling events will occur at that site.
Sampling is complete at the second instrumented site, and the third and fourth sites are currently being monitored.
The third and fourth sites have completed one sample event.
To address nitrogen fate and transport modeling from onsite systems in Florida a simple tool will be developed in
Task D to assist in evaluating nitrogen loading from these systems. This will include development of a soil model to
show how nitrogen is affected by treatment in Florida-specific soils, and a groundwater model to evaluate the movement
of nitrogen down gradient from these systems. A final quality assurance project plan has been completed and the first
steps will include the development of a soil model to show how nitrogen is affected by treatment in Florida-specific
Current Status as of December 2012: Work has focused primarily on soil modeling under the current
budget. Soil models are currently being developed and refined, and the project team has met several times to
discuss and finalize model conditions. Groundwater modeling is underway with conceptual model development
started. These models will be utilized to generate a simple tool for prediction of nitrogen fate, transport, and
removal in Florida soils and groundwater.
The resulting contract, March 2010
amendment, October 2010
January 2012 amendment,
January 2012 renewal, and January 2012
amendment to the renewal split
the study into five main tasks:
Task A: Technology Evaluation for Field Testing: Review, Prioritization, and Development
Task B: Field Testing of Technologies and Cost Documentation
Task C: Evaluation of Nitrogen Reduction Provided by Soils and
Task D: Nitrogen Fate and Transport Modeling
Task E: Project Management, Coordination, and Meetings
Progress Reports to Legislature:
contact the Onsite Sewage Program office with any questions or comments.
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