Q786. How should I report substitute data for the annual volume of landfill gas collected and/or the annual average methane concentration of the landfill gas collected?

A786. If a continuous monitoring system is in place for both methane flow and concentration, and a whole day or more is missed, then the value for substitute data for both the annual volume of landfill gas collected and the annual average methane concentration would be reported as 1+ in the range of 1 to 365 (or 366 in a leap year).  If a small number of measurements were missed in a day for a continuous monitoring system, the procedures in 98.345(a) and (b) should be used to calculate the missing values for that day, but there is no need to report this as substitute data.  If a continuous monitoring system is not in place for methane concentration, and a whole month or more is missed when determining the annual average methane concentration, then the value for substitute data used to determine the annual average methane concentration would be 1+ in a range of 1 to 12. Please note that per section 98.343(b)(2)(ii), there must be at least 14 days between measurements of methane concentration if only one measurement is made each calendar month. The webform and XML schema have changed in RY2013 to reflect the change from the weekly to the monthly monitoring requirement for this parameter. Per section 98.343(b)(2)(i), landfill gas flow must be continuously monitored. Per section 98.343(b)(2)(i), annual average methane concentration in the landfill gas may be monitored either continuously, if such a monitoring system is in place, or monthly.  [See the 2013 Revisions to the Greenhouse Gas Reporting Rule, published in the Federal Register on November 29, 2013, which revised the monitoring requirements for methane concentration to allow for monthly instead of weekly monitoring.]  The annual volume of landfill gas collected and the annual average methane concentration are used in Equation HH-4 to calculate the amount of methane recovered with the landfill gas collection system