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The City of Columbus, Ohio is developing their Long Term Control Plan. A portion of the work consisted of a large, intensive data collection effort, gathering information about the local rivers, stormwater system, combined sewer system, separate sewer system, and wastewater treatment plants. Data collected ranges from mussel surveys on the local rivers to flow monitoring in the combined sewer system. One of the particularly challenging aspects of the projects was achieving stability in the dissolved oxygen calibration for water quality measurement devices installed at 34 locations in area rivers. The dissolved oxygen calibration would drift toward saturation, and then above saturation, during deployment. Tests were conducted to determine the source of the calibration error using aerated tap-water baths. In the end, thicker membranes and longer burn-in time before calibration helped solve this problem and reduce drift in the sensors during deployment. Bacteria concentration was also a parameter of concern. It was found that stormwater was a major bacteria contributor to local streams, and helped increase the stream concentrations above State of Ohio water quality standards, even upstream of the combined sewer system. This immense data collection effort will help the City characterizing the receiving streams in Central Ohio and developing their Long Term Control Plan for CSOs.

With a number of different sources being subjected to many different tests, an intelligent database was needed in order to store all the data so that it would be readily accessible to quality assurance personnel and modelers. The Malcolm Pirnie developed Time Series Analyzer (TSA) program was used to import, check, modify, graph and export the data. An important feature of TSA is that it records any changes to the data, along with the date, time, reason, and individual who made the changes. This maintains the integrity of the original values while recording any changes and their source. This application also adds value to the data because it makes the data more readily accessible, more organized, and in the end provides an electronic deliverable for the City to incorporate with their current database.

Document Type: Research Article


Publication date: 2005-01-01

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