PNM San Juan Generating Station BART Analysis

Modeling Analysis

Black & Veatch performed the initial and re fined modeling analyses using EPA’s default average annual natural visibility conditions. NMED needs an additional modeling analysis reflecting the 20 percent best and worst days vi sibility conditions. To support the additional study, NMED calculated the scaling factors (sho wn in Table 1). The scaling factors were calculated by solving the speci es components in the following light extinction equation:

b ext = (3) f (RH) [ammonium sulfate] + (3) f (R H) [ammonium nitrate] + (0.6) [coarse mass] + (4) [organic carbon] + (1) [soil] + (10) [elemental carbon] + b ray

where bracketed quantities represent background concentrations in ug/m 3

, values in parenthesis represent scattering efficiencies, f (RH) is the relative humidity adjustment factor (applied to hygr oscopic species only),

b ray is light extinction due to Rayleigh scattering (10 Mm -1 used for all Class I areas).

The levels of aerosol components at each Class I areas for the 20 percent best and worst days visibility conditions are then scaled using the scaling factor . The species’ concentrations calculated using the scaling factors are provide d in Tables 2 and 3. All data used in the

calculation is available in Tabl e A-3 and Appendix B of EPA’s Guidance for Estimating Natural Visibility Conditions under the Regional Haze Rule (EPA, 2003). For the additional modeling analysis, use 1 ppb background ammonia concentr ation because of excluding VOC and ammonia emissions from surrounding sources as well as the BART process. Ammonia Limiting Method (ALM) is not acceptable because EPA does not approve it for BART modeling.

Please provide modeling results focusing on the impact of each individual unit as well as combined visibility impacts for the SJGS BART sources at each Class I area reflecting the best and worst days visibility conditi ons. Please use the attached Excel spreadsheet for the results.Table 1. Scaling Factors for Calculating Species’ Concentrations for the 20% Best & Worst Days Natural Visibility Condition in Each Class I Area

Scaling Factors (unitless)
Class I Area 20% Best Days 20% Worst Days

Arches 0.37 1.82

Bandelier 0.37 1.82 Black Canyon of the Gunnison 0.38 1.80 Canyonlands 0.38 1.83 Capitol Reef 0.37 1.81 Grand Canyon 0.36 1.81

Great Sand Dune 0.38 1.79

La Garite 0.38 1.80

Maroon Bells Snowmass 0.38 1.80

Mesa Verde 0.39 1.84

Pecos 0.38 1.81

Petrified Forest 0.37 1.82

San Pedro Parks 0.38 1.82

Weminuche 0.38 1.82

West Elk 0.38 1.81

Wheeler Peak 0.38 1.80Table 2. Species’ Concentrations for the 20% Best Days Natural Visibility Condition in Each Class I AreaSpecies’ Concentration (μg/m3)Class I AreaAmmoniumsulfateAmmoniumnitrateOrganic carbonmass Elemental carbon Soil Coarse MassArches 0.044 0.037 0.174 0.007 0.185 1.108Bandelier 0.045 0.037 0.175 0.007 0.187 1.120Black Canyon of the Gunnison 0.045 0.038 0.177 0.008 0.188 1.130Canyonlands 0.045 0.038 0.176 0.008 0.188 1.125Capitol Reef 0.045 0.037 0.176 0.007 0.187 1.122Grand Canyon 0.043 0.036 0.170 0.007 0.181 1.086Great Sand Dune 0.0450.038 0.178 0.008 0.190 1.137La Garite 0.045 0.038 0.177 0.008 0.188 1.130Maroon Bells Snowmass 0.045 0.038 0.177 0.008 0.188 1.130Mesa Verde 0.046 0.039 0.182 0.008 0.194 1.162Pecos 0.045 0.038 0.176 0.008 0.188 1.126Petrified Forest 0.044 0.037 0.173 0.007 0.184 1.101San Pedro Parks 0.0450.038 0.176 0.008 0.188 1.125Weminuche 0.046 0.038 0.178 0.008 0.190 1.138West Elk 0.045 0.038 0.178 0.008 0.189 1.134Wheeler Peak 0.045 0.038 0.178 0.008 0.189 1.133Table 3. Species’ Concentrations for the 20% Worst Days Natural Visibility Condition in Each Class I AreaSpecies’ Concentration (μg/m3)Class I AreaAmmoniumsulfateAmmoniumnitrateOrganic carbonmass Elemental carbon Soil Coarse MassArches 0.218 0.182 0.854 0.036 0.909 5.451Bandelier 0.218 0.182 0.853 0.036 0.908 5.446Black Canyon of the Gunnison 0.217 0.180 0.848 0.036 0.902 5.415Canyonlands 0.220 0.183 0.861 0.037 0.916 5.495Capitol Reef 0.217 0.181 0.852 0.036 0.906 5.436Grand Canyon 0.217 0.181 0.851 0.036 0.905 5.429Great Sand Dune 0.2150.179 0.841 0.036 0.895 5.370La Garite 0.217 0.180 0.848 0.036 0.902 5.415Maroon Bells Snowmass 0.216 0.180 0.845 0.036 0.899 5.394Mesa Verde 0.220 0.184 0.863 0.037 0.918 5.506Pecos 0.217 0.181 0.852 0.036 0.906 5.436Petrified Forest 0.218 0.182 0.856 0.036 0.910 5.462San Pedro Parks 0.2180.182 0.854 0.036 0.909 5.452Weminuche 0.218 0.182 0.854 0.036 0.909 5.452West Elk 0.217 0.181 0.848 0.036 0.903 5.415Wheeler Peak 0.216 0.180 0.848 0.036 0.902 5.410Request for Additional Cost Evaluation and Additional Review of ROFA Technology

In Appendix Y of 40 CFR 51, Guidelines for BA RT Determinations under the Regional Haze Rule, EPA recommends methods for determining whether the options iden tified in Step 1 are technically feasible (Step 2), and ev aluating impacts analyses (Step 4).

EPA Guidelines offer the following guidance on determining whether a control technology

should be considered technically feasible: “Control technologies are technically feasible if either (1) they have been installed and operated successf ully for the type of source under review under similar conditions, or (2) the technology could be applied to the source under review. Two key concepts are important in dete rmining whether a t echnology could be appl ied: “availability” and “applicability.” As explained in more detail below, a technol ogy is considered “available” if the source owner may obtain it through commerc ial channels, or it is otherwise available within the common sense meaning of the term. An available technology is “applicable” if it can reasonably be installed and operated on the source ty pe under consideration. A technology that is available and applicable is technically feasible.” The analysis of the Mobotec ROFA and ROTAMIX technology did not include a demonstration that this technology is technically infeasible. EPA guidance directs this dem onstration to conclude that the control “option is either commercially unavailable, or that specific circum stances preclude its app lication to a particular

emission unit .” Absent an analysis prescribed in the EPA guidelines, NMED considers this technology both commercially available and appli cable, and NMED request s that the analysis include this technology throughout th e BART determination process.

Sections 4. and 5. of Part a. of Step 4: Met hods of Estimating Costs of Control, provides two options for documenting equipment cost estimates. The Part requires that “ The basis for equipment cost estimates should be documented, either with data supplied by the equipment

vendor” or “by a referenced source (such as the OAQPS Control Cost Manual, Fifth Edition, February 1996, EPA 453/B-96-001)”. This Part further states, “In order to maintain and improve consistency, cost estimates should be based on the OAQPS Control Cost Manual , where possible.”

In its BART analysis, PNM has provided its cost estimate using a third method, an engineering analysis based on Black &Veatch’s past experi ences with the technolog ies reviewed. Supporting data for the cost estimates was provided on a sing le sheet, one for each of the four boiler units listing major cost headings with their associated line item costs from “similar projects”, multiplied by a scaling factor to provide a cost estimate. No documentation was provided for the individual line item costs or supporting the scalin g factors. When told by NMED that the data provided was insufficient to allow for proper regulatory oversight, PNM’s response was to resubmit the same four single page spreadsh eets with modest increases in detail.

After its review of PNM’s second submittal a nd upon reviewing the Appendix Y procedures outlined above, NMED is requiring that an OAQPS Control Cost Manual , Fifth Edition, February 1996, EPA 453/B-96-001 co st estimate be performed. Op tionally, with prior approval of NMED to include a proposed submittal dead line, NMED may approve a submittal of the

vendor-based estimate method.