CONESTOGA & SUSQUEHANNA WATER TREATMENT PLANTS

Challenge
The City of Lancaster needed to upgrade its Conestoga and Susquehanna Water Treatment Plants in order to meet the stringent drinking water quality standards of the EPA's Stage 2 Disinfection Byproducts Rule and the Long-Term 2 Enhanced Surface Water Treatment Rule, both of which are scheduled to be promulgated in early 2006.

Solution
HRG, as a subconsultant to HDR Engineering, conducted an engineering study to reveal the most cost-effective treatment process to meet these stringent standards. Through this study, it was determined that high-performance, low-pressure membranes would be the most cost-effective alternative for the City of Lancaster.

With this established, the engineering team assisted the City of Lancaster in completing a detailed pilot study to evaluate seven different membrane systems. This study, one of the largest municipal low-pressure membrane tests ever to occur in North America , evaluated each of the various manufacturer's systems to determine which one would be the most cost-effective at meeting the city's technical and operational needs.

After procurement of the membrane system, the team initiated the design of the advanced filtration facilities. This presented a number of challenges. For example, portions of the plant's existing infrastructure dated back to the 1930s, so the goal of utilizing this existing infrastructure to meet the demands of modern water treatment practices was difficult with a limited project budget.

Additionally, the wastewater generated by low-pressure membrane systems is difficult to thicken and dispose of through conventional methods. Therefore, a ballasted flocculation process (one of the first applications of this type in the United States) is being installed at the Susquehanna Water Treatment Plant and a second stage membrane system is being installed at the the Conestoga Treatment Plant. This reduced project costs significantly and eased construction staging interferences.

One of the largest membrane filtration drinking water plants in the US …
The Conestoga Water Treatment Plant has a capacity of 12 million gallons per day, and the Susquehanna Water Treatment Plant has a capacity of 24 million gallons per day. By the time construction of the upgraded plants is complete, they will be among the 30 largest membrane filtration drinking water plants in the entire United States.

One of the most experienced membrane filtration experts in the region …
Before embarking on this project, the City of Lancaster believed that membrane filtration would be among the most cost-effective processes for the upgraded treatment plants. As one of the most experienced membrane filtration design firms in the region, HRG was a natural choice for this project.

Over the years, HRG has been involved in the planning, design, and construction of more than 14 membrane filtration plants, with construction costs in excess of $140 million dollars.

© 2008 Herbert, Rowland & Grubic, Inc.