Hydrologic Balance, Water Quality, Chemical-Mass Balance, and Geochemical Modeling of Hyperalkaline Ponds at Big Marsh, Chicago, Illinois, 2016–17

Scientific Investigations Report 2019-5078
Prepared in cooperation with the U.S. Environmental Protection Agency, Brownfields Program, and in collaboration with the City of Chicago’s Park District
By: , and 



Hyperalkaline (pH greater than 12) ponds and groundwater exist at Big Marsh near Lake Calumet, Chicago, Illinois, a site used by the steel industry during the mid-1900s to deposit steel- and iron-making waste, in particular, slag. The hyperalkaline ponds may pose a hazard to human health and the environment. The U.S. Geological Survey (USGS), in cooperation with the Environmental Protection Agency (EPA) and in collaboration with the City of Chicago’s Park District, completed a study to evaluate the hydrologic balance, water quality, and chemical-mass balance of hyperalkaline ponds at Big Marsh and geochemical modeling used to evaluate remediation options for water quality at the site based on data collected in 2016–17.

Synoptic measurements of surface-water and groundwater elevations were used to determine flow directions and to enable a preliminary estimate of the hydrologic balance for the ponds. Water-quality samples also were collected and analyzed for selected constituents including major anions and cations, nutrients, metals, and trace elements. The results of the water-quality analyses were used to develop a geochemical model to evaluate concentrations, factors affecting pH, and the state of equilibrium between surface waters and atmospheric carbon dioxide. The geochemical model was used to evaluate remediation scenarios using riprap, spillways, or active aeration. The results indicate that active aeration will decrease the pH to near 7.5 in about 8 hours, the fastest rate of the scenarios. Passive aeration, such as riprap or spillways, also can be effective at decreasing the pH in about 45 hours, but spatial obstacles limit their implementation. Seasonal variations in temperature also affect the rate of equilibration, where colder temperatures may have a lower pH than warmer temperatures and may affect the timing and frequency of remediation.

Suggested Citation

Gahala, A.M., Seal, R.R., and Piatak, N.M., 2019, Hydrologic balance, water quality, chemical-mass balance, and geochemical modeling of hyperalkaline ponds at Big Marsh, Chicago, Illinois, 2016–17: U.S. Geological Survey Scientific Investigations Report 2019–5078, 31 p., https://doi.org/10.3133/sir20195078.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Methods
  • Hydrologic Balance
  • Water Quality of Hyperalkaline Ponds and Groundwater at Big Marsh
  • Chemical-Mass Balance
  • Geochemical Modeling
  • Implications for Remediation
  • Summary and Conclusions
  • References Cited
  • Appendix 1. Quality-Assurance and Quality-Control Implications of High-pH Waters
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Hydrologic balance, water quality, chemical-mass balance, and geochemical modeling of hyperalkaline ponds at Big Marsh, Chicago, Illinois, 2016–17
Series title Scientific Investigations Report
Series number 2019-5078
DOI 10.3133/sir20195078
Year Published 2019
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Eastern Mineral and Environmental Resources Science Center, Illinois-Iowa-Missouri Water Science Center, Central Midwest Water Science Center
Description Report: vi, 31 p.; Data Release
Country United States
State Illinois
County Cook County
City Chicago
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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