Water Quality in a Changing Environment

Stormwater Sampling, Water Quality Monitoring and Active DOT Construction Sites: Lessons Learned from Two Years of Data

Authors: Melissa Serio (Iowa DOT) , Rebecca Kauten (University of Northern Iowa)

Abstract

In December 2009, the U.S. Environmental Protection Agency (EPA) proposed effluent limitations guidelines (ELGs) to regulate the volume of sediment suspended in water discharging from construction sites. The proposed numerical standard for effluent discharge concentrations of sediment may result in regular water monitoring requirements and other qualitative analysis of stormwater-driven discharges from construction sites.

To date, no numerical standard exists as federal law for effluent discharge of sediment-laden water from an active construction site. After subsequent injunctions filed by the National Homebuilders Association and other stakeholder groups, EPA withdrew the numerical limit of 280 NTU (nephelometric turbidity units) from the administrative rule. However, all non-numerical guidelines remain intact. In 2012, Iowa DOT embarked on a water quality monitoring project with the University of Northern Iowa. The objective was to:

• Identify, perform and recommend water quality monitoring protocols to be used as a means of gathering site-specific data from active construction sites during and following rainfall events of .25 inches or more.
  • Initial literature review and update of existing information.
  • Identify monitoring sites for 2012 and 2013 construction seasons based on Iowa DOT project plans.
  • Collect soil and water samples and record data from sites following .25 inch rainfall events.
• Develop appropriate documentation to allow for broad-scale reproduction on an agency-wide basis.
  • Compare turbidimeter measurement data with manual transparency measurements.
  • Establish distribution curve numbers based on a range of soil types.
  • Document evidence accordingly.
• Produce instruction materials on proper techniques, data management and basic analysis.
  • Present initial and final results to TAC for further evaluation.
  • Summarize data and TAC conclusions.
  • Produce reference materials for Iowa DOT and subcontractor use during future event-based monitoring and data collection.
  • Share information with contracting agency and subcontractors as necessary.

The case study presented as a result of this project recommends methods for basic water quality monitoring, and addresses concerns regarding ongoing sampling on active construction sites.

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How to Cite: Serio, M. & Kauten, R. (2014) “Stormwater Sampling, Water Quality Monitoring and Active DOT Construction Sites: Lessons Learned from Two Years of Data”, National Hydraulic Engineering Conference 2014. 1(2014).