The purpose of the Guideline Manual is to provide recommendations for the application of combined gas reburning-sorbent injection (GR-SI) technologies to pre-NSPS boilers. The manual includes design recommendations, performance predictions, economic projections and comparisons with competing technologies. The report also includes an assessment of boiler impacts. Two full-scale demonstrations of gas reburning-sorbent injection form the basis of the Guideline Manual. Under the U.S. Department of Energy's Clean Coal Technology Program (Round 1), a project was completed to demonstrate control of boiler emissions that comprise acid rain precursors, specifically oxides of nitrogen (NOX) and sulfur dioxide (S02). Other project sponsors were the Gas Research Institute and the Illinois State Department of Commerce and Community Affairs. The project involved demonstrating the combined use of Gas Reburning and Sorbent Injection (GR-SI) to assess the air emissions reduction potential of these technologies.. Three potential coal-fired utility boiler host sites were evaluated: Illinois Power's tangentially-fired 71 MWe (net) Hennepin Unit W, City Water Light and Power's cyclone- fired 33 MWe (gross) Lakeside Unit #7, and Central Illinois Light Company's wall-fired 117 MWe (net) Edwards Unit #1. Commercial demonstrations were completed on the Hennepin and Lakeside Units. The Edwards Unit was removed from consideration for a site demonstration due to retrofit cost considerations. Gas Reburning (GR) controls air emissions of NOX. Natural gas is introduced into the furnace hot flue gas creating a reducing reburning zone to convert NOX to diatomic nitrogen (N,). Overfire air is injected into the furnace above the reburning zone to complete the combustion of the reducing (fuel) gases created in the reburning zone. Sorbent Injection (S1) consists of the injection of dry, calcium-based sorbents into furnace hot flue gas to achieve S02 capture. At each site where the techno!o@es were to be demonstrated, petiormance goals were set to achieve air emission reductions of 60 percent for NO. and 50 percent for SO2. These performance goals were exceeded during long term demonstration testing. For the tangentially fired unit, NOX emissions were reduced by 67.2% and S02 emissions by 52.6%. For the cyclone-fired unit, NOX emissions were reduced by 62.9% and SOZ emissions by 57.9%.