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28 expensive than the other options available. Some agencies do overlay, epoxy-coated rebars, and fiberglass-reinforced poly- not have the requisite expertise and a few others find the tech- mer reinforcing bars. Although not included as an option, nology too complicated. Of the agencies that have never epoxy-coated reinforcing bars are also a corrosion control used or have not used cathodic protection in the last 5 years, system and are primarily used in new structures; however, a 18 responded in the affirmative that they would consider it in few agencies indicated it is the other option for both new and the future, whereas 7 responded in the negative. existing structures. Wyoming also uses crack healers and sealers on existing structures. CORROSION MITIGATION TECHNOLOGIES IN USE IMPLEMENTATION OF CATHODIC PROTECTION SYSTEMS The survey also tried to identify what other corrosion miti- gation technologies the respondents are using. Table 13 sum- As indicated in Table 14, only six agencies have standards marizes the various kinds of corrosion control systems that for design and/or construction specifications governing the agencies use on new and existing structures. Sealers and use of cathodic protection on reinforced concrete structures. concrete overlays are used by a majority of the agencies on Designs of cathodic protection systems are generally per- both new and existing structures. Waterproofing with asphalt formed by agency staff and some of the respondents obtain overlay is primarily used on new structures and waterproof- assistance from a consultant. Some of the agencies that indi- ing membranes are used on both. Admixed corrosion inhi- cated that they use in-house staff to design cathodic protec- bitors, galvanic cathodic protection, and surface-applied tion systems may not have staff with sufficient qualifications, inhibitors are used by a decreasing number of agencies, espe- and at least one has indicated that all systems they have cially for new structures. Impressed current cathodic protec- installed have failed. A NACE-certified Cathodic Protection tion is used by a single agency as a prevention technology. Specialist is involved in the design of the cathodic protection On existing structures, localized zinc point anodes, galvanic system through a consultant only for a few agencies and some cathodic protection, impressed current cathodic protection, agencies use consultants who work in conjunction with the admixed corrosion inhibitors, and surface-applied corrosion material manufacturer or supplier. Rarely is a consultant inhibitors are used by a decreasing number of agencies. The asked to design a system based on Agency Standards and trend indicates that agencies are choosing the simplest options Construction Specifications or a contractor/installer charged with minimal or no monitoring and maintenance require- with design responsibilities. For cathodic protection systems ment. Electrochemical chloride extraction is used by five to perform as desired it is imperative that the design be per- agencies. Four technologies were listed in the "Other" category formed by qualified and experienced personnel using current for new structures: polyester concrete overlay, thin-bonded recommended or standard practice. NACE has a Standard Practice, NACE SP0290-2007, available and it recommends that such activities be performed under the direction of a reg- istered professional engineer or a certified NACE corrosion TABLE 13 specialist or cathodic protection specialist. It is important that CORROSION CONTROL SYSTEMS USED BY RESPONDENTS No. of Respondents Used on Used on TABLE 14 New Existing DESIGN PROTOCOLS AND DESIGN RESPONSIBILITY Corrosion Control Technologies Structures Structures Yes No Waterproofing Membranes 16 18 Does your agency have any standards for design 6 18 Waterproofing with Asphalt Overlay 17 and/or construction specifications governing the use of cathodic protection on reinforced concrete Sealers 27 28 structures? Concrete Overlays 23 29 Design of cathodic protection systems are Specialty Concrete 9 normally performed by: Coatings on Rebars in Repair Areas 12 Agency Staff 13 Admixed Corrosion Inhibitors 12 13 Consultant--Engineering Firm with Access to 6 Surface Applied Corrosion Inhibitors 6 10 NACE-Certified Cathodic Protection Specialist Localized Zinc Anodes (hockey pucks) 19 Consultant--Engineering Firm with Assistance 8 from Manufacturer and/or Installer Impressed Current Cathodic Protection 1 13 Consultant--Engineering Firm Based on Agency 1 Galvanic Cathodic Protection 7 15 Standards and Construction Specifications Electrochemical Chloride Extraction 5 Contractor or Installer 1 Other 4 2 Agency Staff in Conjunction with Consultant 8 Note: Table based on results of Questions 16 and 17 of the survey. Note: Table based on results of Questions 23 and 24 of the survey.
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29 the designer's professional experience include suitable expe- TABLE 16 rience in cathodic protection of reinforced concrete struc- QUALITY CONTROL DURING INSTALLATION tures. Although manufacturers and installers of the systems Performed By Ye s have an intimate knowledge of their products, design by third Agency Staff 18 parties is preferred to allow for a more robust analysis of the Consultant--Engineering Firm with NACE-Certified 4 suitability of the various systems available for the subject Personnel project and the avoidance of any conflict of interest issues. Consultant--Engineering Firm 1 As is the practice in the design of civil structures, it is impor- Contractor, Manufacturer, Installer 8 tant that the manufacturer's and installers be consulted and Independent NACE-Certified or Qualified Cathodic 3 their assistance used by the third-party designers to ensure Protection Inspector that the full knowledge of the system is brought to bear on the No One 0 design. Note: Table based on results of Question 27 of the survey. All cathodic protection systems on bridge structures in Washington State (a total of 3) have been installed using Connecticut, Florida, Indiana, Vermont, and Prince Edward design-build contracts. Colorado, with six reported systems, Island monitor all cathodic protection systems under their has used design-build contracts on 50% (3) of them. One of jurisdiction as depicted in Table 17. The California, Missouri, the major users of this technology, New Brunswick, uses Ontario, and Oregon DOTs monitor a majority of the sys- such contracts on 20% of its projects and another large user, tems. New Brunswick indicated that it does monitor its Florida, uses it on 2% of its projects. This survey result cathodic protection systems, but did not indicate how many appears to be in contrast to the responses received from the of its systems it does monitor. All other responding agencies industry, which indicated that 50% of the cathodic protection do not monitor the cathodic protection systems they have. projects are design-build. In general, the design-build con- Monitoring of the systems is absolutely imperative to its con- tracts are awarded to general contractors with cathodic pro- tinued performance, as unmonitored systems essentially mean tection materials supplier and/or installer as a subcontractor non-performing systems. (Table 15). To obtain the desired performance it is impera- tive that the design-build contractor be required to possess or Table 18 suggests that the majority of the agencies that mon- have access to the skill sets and experience described by the itor their cathodic protection systems use agency staff for that NACE SP0290-2007 Standard Practice. purpose. In some agencies, agency staff and a contractor mon- itor the systems. Nine agencies have at least one trained per- Table 16 shows that the responsibility for quality control son to monitor and maintain their systems and seven agencies during installation is often carried out by the agency staff and believe that they have sufficient personnel to perform the job less frequently by the contractor, manufacturer, or installer. An (Table 19). Seven agencies have a program in place to moni- independent NACE-certified or a qualified inspector or a tor and maintain their cathodic protection systems and five NACE-certified inspector hired through a consultant is used use consultants on a regular basis. Remote monitoring units infrequently. Agency staff performing the quality control is are used by eight agencies. The frequency of remote monitor- most desired; however, agency staff must have the requisite ing; that is, remotely connecting to the system and obtaining qualification and experience to do the job. Quality control by a a status report, might be performed at least once a month for contractor, manufacturer, or installer is not desirable unless impressed current cathodic protection systems. The remote they are required to provide an independent qualified and monitoring system is to be set to obtain system parameters at experienced inspector who can certify that the project was installed in accordance with the project specifications. TABLE 17 NUMBER OF BRIDGES BEING MONITORED TABLE 15 No. No. of FREQUENCY OF DESIGN-BUILD CONTRACTS Agencies Monitored Systems Prince Edward Island, Canada 2 2 Yes No New Brunswick, Canada N/A 85 Cathodic Protection Projects Bid Out as Design-Build 5 19 California 10 20 Projects Generally Awarded to: Connecticut 13 13 Cathodic Protection Materials Provider 0 Florida 71 71 and/or Installer Indiana 15 15 General Contractors with Cathodic Protection 6 Missouri 96 167 Materials Supplier and/or Installer as Subcontractor Ontario, Canada 40 60 General Contractor with an Independent Cathodic 1 Oregon 9 11 Protection Consultant Vermont 1 1 Other 2 N/A = not available. Note: Table based on results of Questions 25 and 26 of the survey. Note: Table based on results of Question 32 of the survey.
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30 TABLE 18 TABLE 20 CATHODIC PROTECTION MONITORING FREQUENCY OF MONITORING Performed By Yes No Remote Monitoring Site Visits Agency Personnel 14 22 Once a week 2 Once every three months 0 Contractor 1 35 Once a month 1 Once every six months 5 Both 6 30 Twice a year 1 Once every year 5 Note: Table based on results of Question 33 of Once a year 4 Once every two years 8 the survey. Once every five years 1 Note: Table based on results of Questions 39 and 40 of the survey. least once a day. The results in Table 20 show that only three agencies meet this criterion. The frequency for galvanic sys- DP-34. These systems were based on the Caltrans design of tems can be as little as once a year. The recommended fre- the same era. Two engineers in the Missouri DOT (MDOT) quency for site visits to ascertain the condition of impressed became familiar with the technology. One of them special- current systems is once a year and galvanic cathodic protection ized in the construction/electrical area and the other in the systems about once every 5 years. Ten agencies meet the materials engineering field. The success of these first instal- impressed current criteria. lations sufficiently impressed the DOT's Bridge Engineer to champion the use of this technology. The department's pol- icy was modified to include the use of cathodic protection CASE HISTORIES technology. At present, there are 167 bridge structures in the state with operational cathodic protection systems. The oldest Several agencies have adopted cathodic protection technol- operating system in the state, slotted with platinumniobium ogy as one of several bridge preservation tools. Five case wire anode, is 23 years old. studies are presented in this section. These case studies high- light various mechanisms that agencies have used to success- MDOT created a formal team to handle cathodic protec- fully implement corrosion mitigation technologies, not just tion technology under their Materials Group. This team was cathodic protection, thereby reducing their maintenance charged with the selection, design, installation, and operation costs and increasing the average service lives of their bridge of all cathodic protection systems in the state. For training structures. purposes, the DOT sent personnel to a cathodic protection training course conducted by a private organization. The DOT Missouri staff also received in-house training and additional training from workshops conducted under the SHRP Showcase Pro- In Missouri all bridge decks and 35% of substructure ele- gram and Demonstration Project 84. In 2000, as the districts ments are exposed to deicing salt. The state's corrosion prob- acquired many of the required skill sets in the use of this lem is characterized as moderate and its average salt usage technology, the formal team was dissolved. The Research rate is the range of 0 to 5 tons per lane-mile per year. Their Group and the Central Bridge Design Office now have one initial experience with cathodic protection technology was expert each in this technology area. In the districts, there are gained in the 1970s during the installation of three conduc- approximately 12 full-time dedicated personnel for moni- tive coke breeze cast iron anode cathodic protection systems. toring the installed systems. Personnel from diverse techni- These cathodic protection systems were installed during cal backgrounds such as Traffic Signal Electricians, Traffic ongoing regular construction projects and were funded by Engineers, Bridge Maintenance Engineers, and Construction Inspectors have acquired cathodic protection expertise. The Traffic Engineers and Signal Electricians use electrical and TABLE 19 RESOURCES FOR MONITORING AND MAINTENANCE electronic systems quite similar to those used in impressed OF CATHODIC PROTECTION SYSTEMS current cathodic protection systems and, therefore, are easily Yes No trained to perform monitoring and maintenance tasks. The Does your agency have any personnel trained to 9 15 Bridge Maintenance Engineers handle the regular mainte- monitor and maintain cathodic protection systems? nance required on the systems and the Construction Inspec- Does your agency have sufficient trained personnel 7 17 tors provide quality control and assurance during installation. to monitor and maintain all cathodic protection This philosophy has allowed MDOT to use their available in- systems under your jurisdiction? house resources to implement the cathodic protection tech- Does your agency use consultants on regular basis to 5 19 nology. Funding for all cathodic protection work comes from monitor and maintain cathodic protection systems? the general maintenance fund and all research on cathodic Does your agency have a program in place to monitor 7 17 protection is performed in-house. and maintain the cathodic protection systems? Are remote monitoring units used to monitor some or 8 16 Design of all cathodic protection systems is also done in- all of the cathodic protection systems? house. The state has developed Standard Specifications based Note: Table based on results of Questions 34 to 38 of the survey. on the AASHTO Guidelines. Design and installation specifica-