PNM San Juan Generating Station BART Analysis 

Modeling Analysis 

Black & Veatch performed the initial and refined 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 visibility conditions. To support the additional 

study, NMED calculated the scaling factors (shown in Table 1). The scaling factors were 

calculated by solving the species components in the following light extinction equation: 

bext = (3) f (RH) [ammonium sulfate] + (3) f (RH) [ammonium nitrate] + (0.6) [coarse mass] + 

(4) [organic carbon] + (1) [soil] + (10) [elemental carbon] + bray

where 

 bracketed quantities represent background concentrations in ug/m3

, 

 values in parenthesis represent scattering efficiencies, 

 f (RH) is the relative humidity adjustment factor (applied to hygroscopic species only), 

 bray 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 provided in Tables 2 and 3. All data used in the 

calculation is available in Table 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 concentration 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 conditions. 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 1.80 
Table 2. Species’ Concentrations for the 20% Best Days Natural Visibility Condition in Each Clas

Species’ Concentration (μg/m3) 

Class I Area 

Ammonium 

sulfate 

Ammonium 

nitrate 

Organic carbon 

mass Elemental carbon S

Arches 0.044 0.037 0.174 0.007 0.Bandelier 0.045 0.037 0.175 0.007 0.Black Canyon of the Gunnison 0.045 0.038 0.177 0.008 0.Canyonlands 0.045 0.038 0.176 0.008 0.Capitol Reef 0.045 0.037 0.176 0.007 0.Grand Canyon 0.043 0.036 0.170 0.007 0.Great Sand Dune 0.045 0.038 0.178 0.008 0.La Garite 0.045 0.038 0.177 0.008 0.Maroon Bells Snowmass 0.045 0.038 0.177 0.008 0.Mesa Verde 0.046 0.039 0.182 0.008 0.Pecos 0.045 0.038 0.176 0.008 0.Petrified Forest 0.044 0.037 0.173 0.007 0.San Pedro Parks 0.045 0.038 0.176 0.008 0.Weminuche 0.046 0.038 0.178 0.008 0.West Elk 0.045 0.038 0.178 0.008 0.Wheeler Peak 0.045 0.038 0.178 0.008 0.
Table 3. Species’ Concentrations for the 20% Worst Days Natural Visibility Condition in Each Cla

Species’ Concentration (μg/m3)

Class I Area 

Ammonium 

sulfate 

Ammonium 

nitrate 

Organic carbon 

mass Elemental carbon S

Arches 0.218 0.182 0.854 0.036 0.Bandelier 0.218 0.182 0.853 0.036 0.Black Canyon of the Gunnison 0.217 0.180 0.848 0.036 0.Canyonlands 0.220 0.183 0.861 0.037 0.Capitol Reef 0.217 0.181 0.852 0.036 0.Grand Canyon 0.217 0.181 0.851 0.036 0.Great Sand Dune 0.215 0.179 0.841 0.036 0.La Garite 0.217 0.180 0.848 0.036 0.Maroon Bells Snowmass 0.216 0.180 0.845 0.036 0.Mesa Verde 0.220 0.184 0.863 0.037 0.Pecos 0.217 0.181 0.852 0.036 0.Petrified Forest 0.218 0.182 0.856 0.036 0.San Pedro Parks 0.218 0.182 0.854 0.036 0.Weminuche 0.218 0.182 0.854 0.036 0.West Elk 0.217 0.181 0.848 0.036 0.Wheeler Peak 0.216 0.180 0.848 0.036 0.
Request for Additional Cost Evaluation and Additional Review of ROFA Technology 

In Appendix Y of 40 CFR 51, Guidelines for BART Determinations under the Regional Haze 

Rule, EPA recommends methods for determining whether the options identified in Step 1 are 

technically feasible (Step 2), and evaluating 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 successfully 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 determining whether a technology could be applied: “availability” 

and “applicability.” As explained in more detail below, a technology is considered “available” 

if the source owner may obtain it through commercial 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 type 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 demonstration to conclude that the control “option is either 

commercially unavailable, or that specific circumstances preclude its application to a particular 

emission unit.” Absent an analysis prescribed in the EPA guidelines, NMED considers this 

technology both commercially available and applicable, and NMED requests that the analysis 

include this technology throughout the BART determination process. 

Sections 4. and 5. of Part a. of Step 4: Methods 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 experiences with the technologies reviewed. Supporting 

data for the cost estimates was provided on a single 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 scaling 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 spreadsheets with modest increases in detail. 

After its review of PNM’s second submittal and 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 cost estimate be performed. Optionally, with prior approval 

of NMED to include a proposed submittal deadline, NMED may approve a submittal of the 

vendor-based estimate method.