PROJECT SUMMARY
The Layfield construction group supplied and installed two custom-sized 45 mil Reinforced HypaFlex CSPE baffle curtains in a 6.8 million-gallon (25.7 million-liter) tank for municipal potable water storage operated by Kern County in Bakersfield, California. The HypaFlex CSPE Baffles replaced two 45 mil reinforced polypropylene (RPP) baffles that had shown premature degradation and tearing due to inadequate chemical resistance to chlorine used as a disinfectant. The reinforced 45 mil HypaFlex CSPE was selected based on its 50-year performance history in water treatment, excellent chemical resistance to chlorine, NSF-61 potable water certification, and durability.
SOLUTION
Two 28’ x 156’ (8.5 m x 47.5m) baffle curtains were custom-fabricated at Layfield’s Lakeside, California, geosynthetic operation. The fabricated baffles included a ¼” stainless steel cable hemmed into the top edge and 6” x 4” stainless steel mounting plates designed for attaching the baffles to the tank’s roof structure. The two side walls and bottom edges of the curtain had a reinforced rope, which supported the baffles, being mechanically connected to vertical steel columns and the concrete floor. The baffle curtains improved water treatment by directing water to flow in a longer, serpentine path through the tank, increasing its residence time with chlorine used as a disinfectant.
CHALLENGES & RESULTS
There were several installation challenges while working inside the steel tank, including tight access, confined space, and internal lighting. Many components, including the two baffles and mounting hardware, were custom-fabricated in Layfield’s production plant in Lakeside, CA, to address these challenges. This eliminated the need for field welding, helping reduce the required installation time. To address the high vertical steel walls, scissor lift equipment with safety harnesses was required to assist the technicians with hosting the material and mechanically connecting the 28’ high curtains.
Another key challenge was preventing galvanic corrosion between stainless steel hardware used for the mechanical connections of the baffle curtains and the tank’s carbon steel structure. Since chlorine and water accelerate corrosion, stainless steel bolts, cables, and bars were required for the installation. To prevent electrochemical reactions and galvanic corrosion, Layfield used special non-metallic plastic insulators that were used with all stainless steel bolts, washers, bars, and brackets to isolate the dissimilar metals and prevent electrochemical reactions.
The total time needed to install the new curtains was 16 days, and they were completed on time and within budget. With over 48 years of experience in the manufacturing, fabricating, and installing geomembrane liners, floating covers, and baffle curtains, Layfield ensured proper materials selection and installation methods were used in this potable water application. Layfield’s prior experience with steel tanks, including the impacts of bimetallic separation, provided the knowledge required to supply corrosion-resistant components for this installation.
