Case Study: The LDAR Alternate WorkPractice: An AWP Primer and Guide to Practical implementation and AWP Cost-Effectiveness

摘要

EPA recently released its final rule for the Alternative Work Practice (AWP), allowing facilities subject to federal leak detection and repair (LDAR) regulations to perform optical imaging as an alternative leak detection work practice. Under the rule, facilities electing to implement the AWP must conduct a combined program with both optical imaging and the standard leak detection method, EPA Reference Method 21. An LDAR program based on optical imaging in place of Method 21 promises equal if not better emission reductions by finding the large leaks sooner than Method 21. However, because the final AWP rule still requires Method 21 monitoring and associated repairs of smaller leaks once per year, maintenance cost savings in the LDAR program are greatly reduced. In this paper, the authors explore the advantages of optical imaging over existing, Method 21-based LDAR programs, provide a brief overview of major AWP requirements, and summarize the results of a 9-month field AWP implementation study. Finally, a detailed analysis of AWP program costs is performed. Based on the field AWP-implementation study and LDAR program cost simulations, AWP programs were determined to be cost-effective in programs where quarterly monitoring was required for most program components, optical imaging was performed at rates at least 3 times greater than Method 21 monitoring rates, and optical imaging instrument costs could be shared with other facilities when the program required less than 100% instrument utilization. If optical imaging costs were not shared, cost-effectiveness could only be demonstrated in the scenarios tested if quarterly monitoring was required 5:1 over annual monitoring in the existing program, and when imaging rates exceeded Method 21 rates by at least 4 times. In an evaluation of program design variables, AWP program cost-effectiveness was greatest when the maximum possible imaging distance (and therefore maximum imaging speed) at the lowest imaging frequency allowed under the AWP was selected.