Water Service - Water Resources

Cahaba Watershed Study Jefferson County Wet Weather Permitting

Client:

Jefferson County
Location:

Cahaba, Alabama
Budget:

$300,000
Hurdle:

Water quality model calibration and negotiations with state and federal regulators. A transient water quality calibration was required that addressed in-stream dissolved oxygen, e.coli and phosphorus.

The Cahaba Watershed Study provided Jefferson County with a comprehensive and defensible strategy supporting a tiered waste load permitting structure for the Cahaba River. Additionally the study provided the initial framework for developing appropriate Total Maximum Daily Loads (TMDLs). To achieve these goals, an integrated water quality assessment program was developed. This program was designed to integrate an analysis of a number of wastewater treatment facilities with all aspects of water quality and quantity on a watershed basis.

 

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The major components of the project work plan included:

 

  1. The development and implementation of comprehensive field program addressing river characteristics, point source loads, and nonpoint source loads during wet and dry weather conditions. In addition to extensive wet weather event sampling, this field program included the installation and operation of several Datasondes for the collection of continuous river water quality and flow information.
  2. The development of a dynamic river water quality and flow model. This model was then under development and based on a recently updated version of the U.S. Corp. of Engineers model CEQUALRIV1. As part of this modeling task, detailed model calibration and verification work was completed.
  3. The development and assessment of variety of wastewater treatment plant (WWTP) operational scenarios in order to establish the technical basis for a tiered WWTP permit.
  4. The calibrated model was expanded to include 120 river miles. The TMDL was based on this enlarged model.
  5. Training was provided to the Alabama Department of Environmental Protection in model development and use.