The Leesburg Wastewater System serves 37,300 residential customers and 2,000 commercial customers in Leesburg, Florida, and the surrounding area. The wastewater system includes 161 lift stations, 81 miles of sewer force mains, and 169 miles of sewer gravity lines. Gravity sewer lines range from 4 to 21 inches in diameter, and force mains range from 4 to 24 inches in diameter.
The city’s 161 lift stations have received upgrades in that time. This case study is on Lift Station 6C, a new 20-foot-deep, 8-foot-diameter sewage lift station installed in 1995. The new precast wet well was lined with a new concrete protective liner system by AGRU America to eliminate microbial-induced corrosion (MIC) in the concrete. The spray-on coating system in the existing wet well had failed.
Problem
Before the 1995 upgrade, the existing Lift Station 6C had a significant wall deterioration and needed a major upgrade. The main cause of failure was MIC in the concrete, which compromised structural integrity, and interrupted service. Station 6C’s three incoming force mains caused water aeration and promoted bacterial growth from increased oxygenation.
Prior solutions were temporary, commonly turning to spray coatings. These coatings need to be inspected annually for cracking, peeling, and separation from the concrete. If repairs are needed, the system has to be shut down, bypassed, and sanitized. Since spray coatings come off with back pressure, leaks must be stopped prior to the application of the spray coating and the surface must be prepared according to the manufacturer’s guidelines.
Solution
The city bought a new precast wet well lined with a permanent concrete protective liner (CPL). The design life of SureGrip concrete protection liners will exceed the structure’s design life under normal operating conditions. SureGrip, manufactured by AGRU America, was selected as the CPL for its longevity, performance history, resistance to corrosion, and long service life.
Outcome
Turner Lining Company has made periodic inspections since installation to monitor the lift station annually. Since 1995, no significant repairs have been needed, and only pressure washing for the inspection has been required.
Since being in service for more than 25 years, the lift station has worked flawlessly with its SureGrip upgrade. “We are pleased with the upgrade to Station 6C and have used AGRU CPL on many of our new lift stations in our collections system,” says city official.
The lift station and liner have held up for 25 years and will likely last another 75. “At this point, the only risk to the system comes from pump replacements that may require minor liner repair around new forced main pipe entries. But if resealed properly, the liner will hold up for another 75 years,” says Wayne Turner of Turner Lining Company.
For more information, contact Cody Miles, Marketing Director for AGRU America at (843) 546-0600 or visit www.agruamerica.com.