Building on 20+ Years of Corrosion Control Optimization with Inhibitor Pre-qualification in Pinellas County Florida

摘要

This paper presents a corrosion inhibitor pre-qualification study for the Pinellas County Water System (PCWS). Pinellas County owns and operates an extensive water distribution network comprising approximately 2,000 miles of water piping, six booster pump stations, ground storage reservoirs, pressure reducing valves and elevated storage tanks that serves nearly 800,000 customers along Florida's central west coast. The sheer size and complexity of the County's system, combined with the use of chloramine disinfection, multiple distribution system points of entry, and variable blend of ground, surface and desalinated sources, makes for a challenging system to monitor and maintain. One of the County's longstanding successes has been their optimized corrosion control program. The success is highlighted by numerous corrosion investigations to resolve corrosion problems that first became apparent through reports of leaking copper pipes in homes and apartment complexes in the early 1970's. Since that time, the County determined a combination of pH control and proprietary orthopolyphosphate corrosion inhibitor addition is the best available practice for controlling lead and copper release. This methodology has remained effective for their regional blended ground, surface and desalted water supply that is disinfected with chloramine. Water supply is provided by the regional water authority, Tampa Bay Water. In light of escalating water treatment chemical costs, the County embarked on a program to pre-qualify alternate products for competitive bidding. This followed prior formal tests of alternative products to the original product in 1994 and 2003. The subsequent testing and competitive bids lead to contract extensions with the original vendor when products with comparable performance were not found or when the price of competitive products was higher.