Solar Mixing Proves Effective for THM Reduction and More

April 1, 2012
By Fred Rouse, Chief Environmental Engineer at Stanley Consultants, and Kathleen Carroll, City of Yuma Water & Wastewater Treatment Manager

As the effective date for the Stage 2 Disinfection Byproducts Rule under subpart V approaches, the City of Yuma was concerned with rising trihalomethanes (THM) concentrations in its water storage facilities. The City's water quality had always met regulatory requirements, but an upward trend in THM concentrations had been noted.

Yuma has one 1.5 million gallon elevated storage reservoir located in Friendship Park and three 3 million gallon ground storage reservoirs located at 16th Street. While researching methods to reduce THM production, the City's water system staff realized that its storage reservoirs were experiencing stratification, short-circuiting, and stagnation especially during the hot summer months where temperatures could easily reach 115°F for weeks at a time.