Challenge

Avon Lake Water Filtration Plant was built in 1926 to serve the city with the capacity of 2 million gallons per day (mgd), producing water for 1,200 people. The city strives to make their drinking water system among the most progressive in the country. Over time the plant’s treatment processes has evolved to improve drinking water quality. The maximum water production capacity recently increased to meet demand of growing population reaching 40 mgd in summer time and providing high quality water to over 200,000 people living within 680 square-miles of a sevencounty area.

In 2013 the decision was made to expand the plant and increase its capacity from 40 to 50 mgd to provide enough drinking water for the growing population over years to come. Increasing the plant’s output meant that the existing chlorine gas disinfection system needs expansion too. The previous installation was supplied by Wallace & Tiernan, Inc. over 45 years ago and operated without any issues. However in 2013, it was decided to couple the disinfection system upgrade with the plant expansion, to further improve site performance and safety to the employees and surrounding community. An additional factor which prompted plant management to invest in re-designing of the disinfection system was to automate the chlorinator control, and switch from full vacuum feed to a pressurized header to allow for better operation with the additional ton containers that needed to be brought online.

Solution

The plant needed expansion of 10 mgd which also required the chlorination system to be expanded in order to supply sufficient amount of chlorine that guarantees sufficient primary and residual disinfection in the drinking water delivered to customers. The higher chlorine output required a completely new design for chlorine gas dosing, metering and control. The Wallace & Tiernan® representative proposed a solution which converted the old manually operated installation into modern and fully automated system.

The installation was converted from full vacuum with dedicated vacuum regulators to each ton container to pressurized system which benefited from pair of 3,000 ppd auto switchover vacuum regulators. The old style chlorinators were replaced with automatic Wallace & Tiernan equipment – V2000™ models – representing the latest technology in chlorine gas metering and control. The automatic chlorinators allow for flow paced control which means that the chlorine dose is adjusted to the plant flow rate. The new control guarantees that the exact amount of chlorine is delivered to drinking water matching the water flow through the plant, without wasting chemical or running the risk of not providing inadequate disinfection dosage.
 

Results

The result is that water is safely and sufficiently disinfected, free from any waterborne pathogens making it fit for drinking and potable use. Additionally, chlorine consumption is optimized thereby reducing the overall plant operating cost. The disinfection system has been converted to the modern, cost efficient, state of the art installation providing highest quality drinking water to over 200,000 consumers.