AWWA WQTC57164

Severe drought conditions during the year 2000 forced the City of Tampa Water Department to pump groundwater from Sulphur Springs into the Hillsborough River Reservoir at a historical maximum rate and duration. The addition of Sulphur Springs water to the river increased total hardness, calcium, chlorides and total dissolved solids. Finished water chloride levels were an order of magnitude higher than typically seen over the past ten years. Following these occurrences, many "red water" complaints were registered in certain portions of the distribution system over a period of a few months. After the use of the groundwater supply was discontinued and the pH in the distribution system was increased, the number of complaints decreased. Following a recommendation of an expert panel the city commissioned an experimental testing program with the objective of evaluating control strategies that, assuming the use of groundwater, may minimize the release of Fe and particles (turbidity) from the existing pipe walls and tubercles. The experiments were conducted in a closed-loop configuration. Fourteen identical testing apparatuses were constructed from selected pipe sections from the distribution system along with off-the-shelf materials. The results from these experiments were used to determine: the appropriate settings for pH to minimize scale and iron corrosion; and, the maximum total dissolved solids and chloride concentrations that could be used without causing significant corrosion. By operating the system with pH, total dissolved solids and chloride concentration within the limits established during testing, the city has been able to resume the blending of the ground and surface water sources without compromising the quality of water delivered to customers. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2002

Number of Pages:

11

File Size:

1 file , 280 KB