Common use of Emission-Estimating Methodology Development Clause in Contracts

Emission-Estimating Methodology Development. ‌ The EPA developed an EEM to estimate daily and annual NH3 emissions from swine and dairy lagoons. Section 5 describes the statistical methodology used to analyze the data and develop the EEMs. The EPA is currently developing EEMs for H2S emissions. Because VOC emissions data were not submitted to the EPA, EEMs for this pollutant were not developed. The EPA was unable to develop EEMs for VOCs, as the data for lagoon sources was not received. Sections 3 and 4 discuss the NAEMS data received by the EPA to date. The EPA used the continuous emissions, meteorological and lagoon data and categorical data collected under the NAEMS and SAS® statistical software to develop the NH3 EEMs for swine and dairy lagoons. In the NAEMS documentation, the terms “lagoon” and “basin” were used inconsistently to describe the impoundments at the various monitoring sites. Although the EPA acknowledges that there might be differences between a lagoon and a basin (e.g., the degree of microbial activity), the term “lagoon” is used throughout this report to refer to lagoons and basins. All of the NAEMS meteorological, lagoon and categorical data were assessed for data completeness and statistically evaluated to determine if they were reasonable predictor variables. In addition, the EPA evaluated whether the predictor variables that would be used in the EEM would be readily available to the growers, state and local agencies and other interested parties. The EEM input parameters based on the continuous data are the ambient temperature, relative humidity, solar radiation (represented by ▇▇▇▇▇▇ ▇▇▇) and wind speed. Due to the very limited amount of data received for the nitrogen concentration, solid content and pH of the lagoon liquid, these data were not included in the EEM. The limited number of sites monitored under the NAEMS also limited the number of categorical (i.e., static) variables that could be included in the EEM without compromising the performance of the methodology to two variables. The EPA developed three EEM variations to evaluate the paired combinations of the following three categorical variables that were expected to have the greatest influence on NH3 emissions from lagoons: animal type, farm size and lagoon surface area.