Distribution of effluent injected into the Boulder Zone of the Floridan aquifer system at the North District Wastewater Treatment Plant, southeastern Florida, 1997–2011

Scientific Investigations Report 2017-5145
Prepared in cooperation with the Miami-Dade Water and Sewer Department
By:

Links

  • Document: Report (14.8 MB pdf)
  • Data Release: USGS data release - SEAWAT Data Sets for Simulation of Effluent Transport in the Floridan Aquifer System at the North District Wastewater Treatment Plant, Southeastern Florida, 1997-2011: U.S. Geological Survey Data Release
  • Download citation as: RIS | Dublin Core

Abstract

Nonhazardous, secondarily treated, domestic wastewater (effluent) has been injected about 1 kilometer below land surface into the Boulder Zone of the Floridan aquifer system at the North District Wastewater Treatment Plant in southeastern Florida. The Boulder Zone contains saline, nonpotable water. Effluent transport out of the injection zone is a risk of underground effluent injection. At the North District Wastewater Treatment Plant, injected effluent was detected outside the Boulder Zone. The U.S. Geological Survey, in cooperation with Miami-Dade Water and Sewer Department, investigated effluent transport from the Boulder Zone to overlying permeable zones in the Floridan aquifer system.

One conceptual model is presented to explain the presence of effluent outside of the injection zone in which effluent injected into the Boulder Zone was transported to the Avon Park permeable zone, forced by buoyancy and injection pressure. In this conceptual model, effluent injected primarily into the Boulder Zone reaches a naturally occurring feature (a karst-collapse structure) near an injection well, through which the effluent is transported vertically upward to the uppermost major permeable zone of the Lower Floridan aquifer. The effluent is then transported laterally through the uppermost major permeable zone of the Lower Floridan aquifer to another naturally occurring feature northwest of the North District Wastewater Treatment Plant, through which it is then transported vertically upward into the Avon Park permeable zone. In addition, a leak within a monitoring well, between monitoring zones, allowed interflow between the Avon Park permeable zone and the Upper Floridan aquifer. A groundwater flow and effluent transport simulation of the hydrogeologic system at the North District Wastewater Treatment Plant, based on the hypothesized and non-unique conceptualization of the subsurface hydrogeology and flow system, generally replicated measured effluent constituent concentration trends. The model was calibrated to match observed concentration trends for total ammonium (NH4+) and total dissolved solids.

The investigation qualitatively indicates that fractures, karst-collapse structures, faults, or other hydrogeologic features may permit effluent injected into the Boulder Zone to be transported to overlying permeable zones in the Floridan aquifer system. These findings, however, are qualitative because the locations of transport pathways that might exist from the Boulder Zone to the Avon Park permeable zone are largely unknown.

Suggested Citation

King, J.N., and Decker, J.D., 2018, Distribution of effluent injected into the Boulder Zone of the Floridan aquifer system at the North District Wastewater Treatment Plant, southeastern Florida, 1997–2011: U.S. Geological Survey Scientific Investigations Report 2017–5145, 52 p., https://doi.org/10.3133/sir20175145.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Hydrogeologic Setting
  • Conceptual Model of Effluent Transport From the Boulder Zone
  • Simulation of Effluent Transport
  • Simulated Concentrations of TDS and Total Ammonium (NH4+) and Potentiometric Head
  • Boulder Zone Confinement
  • Simulated Extent of the Effluent Plume in 2011
  • Limitations
  • Summary and Conclusions
  • References Cited
  • Appendix 1. Summary of Simulation of Transport Duration and Path

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Distribution of effluent injected into the Boulder Zone of the Floridan aquifer system at the North District Wastewater Treatment Plant, southeastern Florida, 1997–2011
Series title Scientific Investigations Report
Series number 2017-5145
DOI 10.3133/sir20175145
Year Published 2018
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Caribbean-Florida Water Science Center
Description Report: vii, 52 p.; Data Release
Country United States
State Florida
Online Only (Y/N) Y
Additional Online Files (Y/N) Y