Coatings Management Program for a Large Wastewater Treatment Plant
By Mike A.Oriol, Coatings Division Manager and Manuel Najar, P.E.
Sacramento Regional Wastewater Treatment Plant (SRWTP), built in 1980, handles 160 million gallons per day. The plant has various treatment processes operating simultaneously. Within those treatment processes, there is steel and concrete exposed to corrosive environments, which can quickly reduce the life expectancy of a structure and increase maintenance costs. As part of an overall corrosion control assessment of the plant, V&A conducted a survey of some of the coated and uncoated structures within the SRWTP in order to create a Coatings Management Program. The following article will provide an overview of the efforts made to provide SRWTP with the information needed to implement a Coatings Management Program.
IDENTIFICATION OF COATING NEEDS
V&A conducted several walk-through assessments in different parts of the plant ranging from the influent junction structure, primary sedimentation tanks, digesters, secondary clarifiers, and chlorine contact basins. Some structures were coated. However, the majority were uncoated below the wastewater surface. Photos 1 and 2 show some of the conditions observed at the SRWTP.
Photo 1: Small exposed aggregate on floor of bar screen channel.
Photo 2: Delaminated PVC liner in a secondary clarifier tank.
V&A noted the type of coated substrate (steel or concrete), the exposure (submerged or above wastewater surface), and any defects observed. Some structures, like the digesters, could not be shut down for observation. In these cases a previous 1994 report was used to identify the existing coating system and estimate the remaining life. V&A also reviewed SRWTP's existing painting specification and rewrote a new master coating specification for steel and concrete exposed to wastewater environments. Based on the available data, the coating with the greatest need of replacement was the coal tar epoxy on the digesters and the secondary clarifier effluent channels. With all of the coating information collected, V&A proceeded with making recommendations on how to implement a coatings program, including methods, materials, budget, and schedule.
IMPLEMENTING THE COATINGS PROGRAM
V&A created a priority list of structures to be coated that was based on the condition of the existing coating, remaining life, and SRWTP's recommendations. Groups of structures to be coated were created with the greatest coating needs at the top of the list (highest priority). There was a total of 25 coating groups to be recoated or replaced over a period of 25 years. SRWTP provided V&A with the dimensions of the structures and tanks so that the cost to coat each structure could be estimated. The cost per year of coating a group of structures ranged from $151,200 to $2.3 million.
The success of a Coatings Management Program often hinges on the support received from a treatment plant’s Board of Directors, General Manager, Chief Engineer, Chief Operations and Maintenance Manager, and line workers. A Coatings Management Program cannot be successful without the support of all of the parties impacted. Therefore, the selection of a responsible professional to manage the Coatings Management Program is a critical factor that all public agencies must evaluate if they are considering implementing a Coatings Management Program. V&A has seen Coatings Management Programs stall primarily because no single individual was responsible for the program. A Coatings Management Program will evolve as projects are planned, designed, operated and maintained.
For the first few years, V&A recommended that an outside consultant help run the Coatings Management Program with the assistance of an SRWTP engineer. V&A also recommended that SRWTP consider a competitive bid for 1-year to 3-year coatings procurement contracts in order to reduce costs and provide consistency in the coating systems being used at the plant.
V&A's Experience with Coatings Management Programs
V&A has assisted public agencies and private companies with creating coating standard details and specifications and implementing Coatings Management Programs. V&A has extensive experience in conducting condition assessments of existing protective coating systems. V&A engineers have completed C-1 (Fundamentals of Protective Coatings for Industrial Structures) and C-2 (Specifying and Managing Protective Coatings Projects) training by SSPC, The Society for Protective Coatings. Contact V&A at the number below if any further information or guidance is needed with respect to these services.
Jim Eggenberger Joins V&A Oakland
Jim Eggenberger is a NACE Level IV Cathodic Protection Specialist with over 27 years of experience in corrosion control. His work has focused on cathodic protection system design; corrosion investigations, post-installation testing, cathodic protection system installation, stray current studies, supervision and construction project management; for a wide variety of structures—water, wastewater and transit systems. He has an extensive background in transit system testing and project management and has worked on a wide variety of transit projects for the Santa Clara Valley Transportation Authority in Santa Clara, CA, for the Bay Area Rapid Transit District (BART) in the San Francisco Bay Area and Sound Transit projects in Seattle, WA.
His water and wastewater projects have included such structures as water storage tanks, piers and piling, wastewater treatment facilities, pipelines, water pipelines, locks and dams, underground utilities at military installations, and above ground storage tank facilities.
Jim Eggenberger
Photo 2: Exposed 42 Inch Water Transmission Pipeline Connection
