Layfield completed supplying and installing HypaFlex™ CSPE liner and floating cover system as part of a refurbishing and upgrade project for Pittsburgh Water & Sewer Authority’s (PWSA) Lanpher Reservoir. The Lanpher Reservoir is a double reservoir, potable water storage system (East & West reservoirs) with a total capacity of 146 million gallons. The reservoir has a long history and was originally constructed in 1913. It was one of the first water reservoirs in the region to use chlorine for disinfectant.
Solution and Insatllation
This reservoir system upgrade included concrete restoration repairs and a newly designed liner and floating cover system. The material selected for the new geomembrane liner and the floating cover was a 60 mil (1.5 mm) thick reinforced HypaFlex™ CSPE (Chlorosulfonated Polyethylene) product.
The installation was performed over a 2-year period and faced a number of site challenges, including unseasonably wet and cold weather conditions. The two reservoirs were also quite deep at 40′ (12.2m) with a steep 2:1 slope, creating challenges for material deployment and welding during installation. The project scope also included demolishing and removing an older liner and cover material.
To help expedite the installation during poor weather conditions, Layfield relied on using larger prefabricated factory-made panels, which significantly reduced the amount of field welding required on site. In total, the project included the installation of 1,600,000 square feet (148,644 m2) of 60 mil reinforced grade HypaFlex™ CSPE liner and cover material. This included 900,000 ft2 (83,612 m2) in the West reservoir and 700,000 ft2 (65,032 m2) in the East reservoir. The floating cover was mechanically anchored to a concrete perimeter edge located at the top of both reservoirs.
Floating covers are designed to eliminate evaporation and protect water from outside debris and contamination. Open top reservoirs with floating covers provide an economical solution for storing large quantities of water and reduce water treatment costs, including the required amount of disinfectant in the treatment process.
All project stakeholders were satisfied with the quality of the installation and materials selected. PWSA made the decision to invest in HypaFlex™ CSPE to ensure the long-term protection of Pittsburgh water and provide proven performance value to the citizens of Pittsburgh.
Fraser B., Roades S., and Neil M., (2019) “CSPE Performance and History in long term Potable Water Storage Applications” Geosynthetics 2019, Houston Texas, IFAI
Los Angeles Department of Water & Power (LADWP) Upper Stone Canyon Reservoir Returns to Service with Newly Installed CSPE Floating Cover. (Los Angeles Department of Water & Power. 2019)