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Appendix 3.1

Responsiveness Summary

During the public comment period, the NDEQ received comments from the following interested 

parties: 

United States Environmental Protection Agency – Region 7

State of Colorado – Department of Public Health and Environment, Air Division

United States Department of the Interior – Air Resources Division 

United States Department of Agriculture – Forest Service 

Twin Platte Natural Resources District

National Parks Conservation Association

The following paragraphs summarize the comments received. Where appropriate, comments 

have been combined and responses consolidated. Any changes to the SIP document have been 

clearly identified in this summary document.

Comment 1: Interstate Consultation

The US Environmental Protection Agency- Region VII (EPA) asked that NDEQ provide 

confirmation that SO2 reductions are no longer needed from the Nebraska sources in order to 

achieve visibility goals in nearby States that host Class I areas and that NDEQ address the 

differences between the assumptions made by the states in estimating the visibility improvement 

needed to meet their reasonable progress goals (RPGs) and what is actually being proposed in 

the NDEQ State Implementation Plan.

Response to Comment 1:

NDEQ consulted with nearby states that host Class I areas at two important points during our SIP 

development process outside of the CENRAP process. First, because we understood that the 

BART determinations were different than what they may have been expecting for reductions 

from Nebraska, we provided an opportunity to comment on the BART permits for both OPPD 

NCS and NPPD GGS. The state of Colorado provided comments on the NPPD GGS permit for 

Nebraska to consider, which we evaluated. The second opportunity was during the proposal of 

the SIP. The state of Colorado provided further comment for NDEQ to consider. Those 

comments are addressed in this summary. No other states have provided comment or feedback. 

NDEQ thinks that it would be most appropriate to address whether nearby states are meeting 

their reasonable progress goals and whether additional measures are needed from Nebraska 

sources during the periodic reviews of the SIPs. 

Comment 2: Significance of Visibility Improvement as a Metric

The EPA made comments related to the use of a significance threshold. EPA noted that NDEQ 

argued that SO2 controls were not being required at Omaha Public Power District Nebraska City 

Station (NCS) and Nebraska Public Power District‟s GGS Station (GGS) in part because the 

visibility improvement gained by SO2 control at those facilities is not significant enough to 

warrant the cost of control. EPA is requesting explanation of the criteria used to determine 

significance (ex. single threshold, number of days the threshold can be exceeded, percent change 
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in improvement, or comparison of the number of days where the threshold is exceeded). The 

EPA also asked how the significance of the visibility improvement does or does not justify the 

level of control in the context of the BART determinations and the overall Long Term Strategy. 

Colorado commented on a similar issue with regard to the NPPD GGS NOx control analysis. 

They provided an example of how they determined significance. Colorado believed that LNB 

with OFA and SCR is cost effective given the tonnage of NOx reduced. Colorado used a NOx 

control cost criteria of <$5,000 per ton along with visibility improvement of 0.5 dv to inform 

the appropriateness of SCR controls. 

Response to Comment 2:

NDEQ agrees with EPA that a discussion regarding the decision making process should be 

included in the SIP. In preamble of the final Regional Haze Rule and BART Guidelines (July 6, 

2005), EPA discusses the flexibility provided to states in establishing such criteria for making 

such decisions:

“Because each Class I area is unique, we believe States should have flexibility to assess visibility 

improvements due to BART controls by one or more methods, or by a combination of methods, 

and we agree with the commenters suggestions to do so. We believe the maximum 24hour 

modeled impact can be an appropriate measure in determining the degree of visibility 

improvement expected from BART reductions (or for BART applicability). We have pointed out; 

however, that States should have flexibility when evaluating the fifth statutory factor. A State is 

encouraged to account for the magnitude, frequency, and duration of the contributions to 

visibility impairment caused by the source based on the natural variability of meteorology. These 

are important elements to consider as they would provide useful information on both the short 

term peak impact and long term average assessments which are critical in making the visibility 

assessment.

We agree with the suggestion that the use of a comparison threshold, as done for determining if 

BART-eligible sources should be subject to a BART determination, is an appropriate way to 

evaluate visibility improvement. However, we believe the States have flexibility in setting 

absolute thresholds, target levels of improvement, or de minimis levels since the deciview 

improvement must be weighed among the five factors, and States are free to determine the weight 

and significance to be assigned to each factor. For example, a 0.3, 0.5, or even 1.0 deciview 

improvement may merit stronger weighting in one case versus another, so one „„bright line‟‟ may 

not be appropriate.

In addition, comparison thresholds can be used in a number of ways in evaluating visibility 

improvement (e.g. the number of days or hours that the threshold was exceeded, a single 

threshold for determining whether a change in impacts is significant, a threshold representing an 

x percent change in improvement, etc.) Other ways that visibility improvement may be assessed 

to inform the control decisions would be to examine distributions of the daily impacts, determine 

if the time of year is important (e.g. high impacts are occurring during tourist season), 

consideration of the cost-effectiveness of visibility improvements (i.e. the cost per change in 

deciview), using the measures of deciview improvement identified by the State, or simply 

compare the worst case days for the pre- and post-control runs. States may develop other methods 

as well.”
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NDEQ added a general discussion to Section 10.4 describing the factors that informed the 

process and summaries in Sections 10.5 and 10.6 explaining how each source fit into that 

process. 

NDEQ also used a $5,000 incremental cost per ton threshold for determining cost effectiveness 

for incremental costs for SCR.

Comment 3: Use of the $/deciview ($/dv) 

EPA has concerns with NDEQ‟s use of the $/dv metric as follows:

Although the BART rules allow for States to use a $/dv metric in evaluating cost 

effectiveness, EPA is concerned that NDEQ is using this as the sole factor in making the 

BART determination.

EPA believes that the $/dv metric is less meaningful because it does not take into account 

visibility impacts at multiple Class I areas or ignores the total improvement. EPA 

contends that it only accounts for the “worst day” of improvement scenario instead of 

taking into consideration multiple days of improvement.

EPA believes the $/dv metric would be more meaningful if put into the context of 

significance of visibility improvement. The United States Forest Service (USFS) also 

provided this same comment. The USFS believes the $/dv should consider the total 

visibility benefit across multiple Class I areas. 

EPA provided a list of BART sources from Oregon, Wyoming, North Dakota, and South Dakota 

along with the BART cost information, visibility improvement and their $/dv analysis to put it 

into perspective. 

The NCPA and FLMs raised concerns with using cost per deciview as a metric of costeffectiveness. They believe there are several flaws in the use of this metric in NDEQ‟s BART 

determinations. First, incremental cost per deciview is almost exclusively emphasized as a 

metric of cost effectiveness. The total cost per deciview, instead, should be used as a supplement 

to cost per ton as a means of evaluating cost-effectiveness. Second, the fact that the potential 

control efficiency of the technologies evaluated is routinely underestimated (see above) will also 

lead to underestimated benefits as far as deciview reduction (visibility improvement). Third, as 

described below, costs are overestimated. The combination of overestimated costs and 

underestimated visibility improvement means that the cost per deciview metric is routinely (and 

significantly) inflated in NDEQ‟s calculation. All of the cost per deciview values cited by the 

draft BART determinations should be reevaluated and appropriately revised. 

Fourth, the cost per deciview metric is more appropriately evaluated in the context of the total 

improvement that the control measure is responsible for. Thus, it should take into account the 

cumulative benefit over all relevant Class I areas, not simply the most heavily impacted one. 

Additionally, the total improvement as far as frequency, magnitude, and duration of visibility 

changes should be taken into account when comparing cost per deciview metrics. 

Finally, once an accurate cost per deciview value is established, it can be compared to cost per 

deciview measures from other BART determinations. Around the country, proposed BART 

determinations have exceeded $50 million, with averages in the $14-18 million range. Based on 
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the issues listed above, we ask that NDEQ reevaluate the benefits associated with the control 

technologies proposed in its BART determinations, rerun modeling to reflect the higher levels of 

control that are achievable, and recalculate total cost effectiveness measures based on accurate 

cost estimates.

Response to Comment 3:

NDEQ understands the concerns raised and believes that the response to Comment 2 along with 

changes to the SIP document addresses the concerns raised. 

Additionally, NDEQ would like to clearly state that it did not rely solely on one factor in making 

its BART determinations, but rather, considered all of the statutory factors. Furthermore, the 

EPA‟s citation of the $/dv metric as only one factor is mistaken, since by definition, this 

calculated ratio includes both the cost and the benefit (degree of visibility improvement). The 

other factors (the energy and non-air quality environmental impacts of compliance, any existing 

pollution control technology in use at the source, and the remaining useful life of the source) 

were also considered in the analysis. Therefore, Nebraska has indeed considered all factors and 

has not relied on a single factor in its BART determinations.

The Clean Air Act, Section 169A (g) (2) states:

“in determining best available retrofit technology the State (or the Administrator in determining 

emission limitations which reflect such technology) shall take into consideration the costs of 

compliance, the energy and non-air quality environmental impacts of compliance, any existing 

pollution control technology in use at the source, the remaining useful life of the source, and the 

degree of improvement in visibility which may reasonably be anticipated to result from the use of 

such technology”

EPA‟s initial Regional Haze rules had directed states to set BART emissions limits based on 

only the first four factors listed in the above statutory language, after determining that a given 

source was “subject” to BART. Thus, EPA had initially left the visibility improvement factor out 

the BART determination step. In the case of American Corn Growers Assn v. EPA (291 F.3d 1; 

D.C. Cir., 2002), the court sided with the American Corn Growers Association, and ruled that all

five factors, including the “degree of visibility improvement” needed to be considered in the 

BART determination. EPA subsequently revised the Regional Haze rules accordingly, on July 6, 

2005. In the preamble, EPA clearly provides discretion to states: 

“As we noted in 2004, this estimate of visibility improvement does not by itself dictate the level 

of control a State would impose on a source; „„the degree of improvement in visibility which may 

reasonably be anticipated to result from the use of [BART]‟‟ is only one of five criteria that the 

State must consider together in making a BART determination. The State makes a BART 

determination based on the estimates available for each criterion, and as the CAA does not 

specify how the State should take these factors into account; the States are free to determine the 

weight and significance to be assigned to each factor...we believe the States have flexibility in 

setting absolute thresholds, target levels of improvement, or de minimis levels since the deciview 

improvement must be weighed among the five factors, and States are free to determine the weight 

and significance to be assigned to each factor. For example, a 0.3, 0.5, or even 1.0 deciview 

improvement may merit stronger weighting in one case versus another, so one „„bright line‟‟ may 

not be appropriate.”
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NDEQ evaluated all the factors and made its determination based upon taking each one into 

careful consideration. It is clear from the guidance provided in the preamble that decisions on 

BART were left to the States and that when making such decisions, individual circumstances can 

and should be taken into account. It is impractical for EPA to take such individual circumstances 

into account when developing a national rule that is the reason for State discretion to account for 

unique or special circumstances, such as: lack of attribution to a distant Class I area, significantly 

increased solid waste disposal requirements, and constraints on obtaining new water due to local 

restrictions, state law, moratoriums, multi-state compacts, and federal agreements. 

NDEQ also evaluated the information provided by EPA regarding the BART determinations in 

several other states. The evaluation was done to determine whether other states utilized the $/dv

metric in a manner contrary or comparable to Nebraska. NDEQ evaluated the benefit at the 

closest Class I areas, consistent with the Regional Haze rule, which were still >300 km away 

from the sources. NDEQ reviewed the proposed SIPs of the other states, to determine whether

the metric NDEQ used was consistent with that of the other states. NDEQ found that the $/dv

methodology utilized by NDEQ appeared to be consistent with that of the states in the table. 

NDEQ also found that the $/dv were significantly higher for the Nebraska sources than those of 

the other states. NDEQ attributes this difference to one of two reasons 1) sources being closer to 

Class I areas and thus having more impact/benefit or 2) cost to retrofit the source being lower 

than that of the Nebraska sources. The table detailing the comparison, Table 10.19, was added to 

Section 10.6.4.10. 

Comment 4: Control Efficiencies

EPA commented that NDEQ should evaluate feasible control technologies using the most 

reasonable control efficiency possible. They went on to state that it is their experience flue gas 

desulfurization units can operate as low as 0.02 lb SO2/MMBtu. 

The National Parks Conservation Association (NPCA) out of Knoxville, TN and Plains Justice 

(PJ) out of Billings, MT submitted a joint comment letter regarding the adequacy of the BART 

determinations . The NPCA/PJ believe that NDEQ did not follow the BART guidelines or 

otherwise meet the intent of the BART requirements because it did not evaluate the most 

stringent option available for reducing emissions from the state‟s EGUs from technologies such 

as Selective Catalytic Reduction and wet and dry scrubbers. 

They state that the NDEQ‟s evaluations assumed that SCR is capable of achieving 0.08 

lbs/mmbtu NOx. In reality, SCRs are being permitted at and can achieve levels of 0.05 

lbs/mmbtu or less on an annual basis and 0.06 lbs/mmbtu on a 30 day rolling average. 0.08 

lbs/mmbtu reflects no more than 83% reduction from current emissions; SCR is well known to 

be capable of control efficiency greater than 90%. 

Their review of recent SCR retrofits at other power plants they believe definitively proves that 

very high levels of NOx removal are being achieved by recent SCR retrofit installations. NOx

emission rates less than 0.05 lb/MMBtu are routinely achieved, and NOx removal efficiencies are 

typically at least 90%. Permitting agencies have required lower NOx limits in recent BACT 

determinations, with many proposed and required BACT limits of 0.05-0.06 lb/MMBtu. For 

example, the Plant Washington PSD permit, issued in April 2010, requires that unit to meet a 
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0.03 lb/MMBtu annual average NOx limit as BACT. The Desert Rock PSD permit includes a 

NOx BACT limit as low as 0.035 lb/MMBtu.

Likewise, the NPCA/PJ and USFS believe that NDEQ BART determinations underestimate the 

emissions levels achieved with SO2 controls, assuming control efficiencies no more than 87% 

and corresponding emission levels between 0.1 – 0.15 lbs/mmbtu. However, modern SO2

controls are capable of reducing emissions by more than 99% to less than 0.04 – 0.06 lbs/mmbtu, 

depending on the technology.

In addition, they believe the state provided no evidence that the emission levels set in association 

with the use of Low NOx Burners/Overfire Air (LNB/OFA) or each facility‟s existing particulate 

matter controls actually reflect the most efficient use of the technology, rather than simply 

presumptive BART (0.23 lbs/mmbtu) in the case of NOx and LNB/OFA, or the existing permit 

limits (0.10 lbs/mmbtu) in the case of PM and existing baghouses or electrostatic precipitators. 

At a minimum, they believe these limits should be set with knowledge of what current emission 

levels are being achieved as well as what emission levels have been achieved elsewhere.

Response to Comment 4:

States must identify the “best” system of continuous emission control technology for each source 

subject to BART taking into account the technology available, the costs of compliance, the 

energy and non-air quality environmental impacts of compliance, any pollution control 

equipment in use at the source, the remaining useful life of the source, and the degree of 

visibility improvement that may be expected from available control technology. NDEQ believes 

that EPA does not mean that a “maximum” level of control must be evaluated, but that when 

considering all of the factors, the State must select the best alternative for control, given the 

individual circumstances.

In the preamble to the final rule, EPA speaks to the issue of the level of emission control:

“We received a few comments expressing the belief that the presumptive limits should be more 

stringent, given that BART emission limits will not be fully implemented until 2013 or 2014. 

We recognize that while some scrubber units currently achieve reductions greater than 95 

percent, not all units can do so (emphasis added). The individual units that currently achieve 

greater than 95 percent control efficiencies do not necessarily represent the wide range of unit 

types across the universe of BART-eligible sources. An analysis of the Department of Energy‟s 

U.S. FGD Installation Database supports our belief that 95 percent removal efficiencies would 

be obtainable by all types of EGUs burning medium and high sulfur coal by 2014, including 

BART-eligible EGUs. In addition, we note that the presumption does not limit the States‟ ability 

to consider whether a different level of control is appropriate in a particular case. If, upon 

examination of an individual EGU, a State determines that a different emission limit is 

appropriate based upon its analysis of the five factors, then the State may apply a more or 

less stringent limit (emphasis added).”

It is difficult to ascertain the maximum efficiency the technology could achieve at the source 

until it is installed and optimized. However, NDEQ believes the point is to have the State 

consider other possible efficiencies the technology could achieve when determining whether 

something is cost effective. NDEQ did consider a lower lb/MMBtu than the presumptive level.
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To determine whether the levels at which NDEQ evaluated were appropriate for SO2 control, 

NDEQ retrieved data from the EPA database to determine how existing FGD systems performed 

at existing sub-bituminous coal fired EGUs. While units were found that performed at or below 

0.1 lb/MMBtu, NDEQ did not find where levels as low as 0.02 lb/MMBtu were being met, and 

several did not meet the 0.15 lb/MMBtu presumptive level. See table below.

2009 SO2 Emissions & Controls on Electric Generation Units

State Plant Name Unit SO2 TPY SO2

lb/MMBtu Boiler Type SO2 Controls

CO Craig C1 1,083.3 0.0615 Dry bottom Wet Limestone

CO Craig C2 1,125.5 0.0638 Dry bottom Wet Limestone

CO Craig C3 1,686.3 0.1161 Dry bottom Dry Lime FGD

CO Rawhide 

Energy Station 101 1,060.8 0.0875 Tangentially-fired Dry Lime FGD

KS Holcomb SGU1 1,948.3 0.1413 Dry bottom Dry Lime FGD

KS Jeffrey Energy 

Center 1 653.2 0.0280 Tangentially-fired Wet Limestone

KS Jeffrey Energy 

Center 2 4,092.6 0.1790 Tangentially-fired

Wet Limestone 

(Began Apr 01, 

2009)

KS Jeffrey Energy 

Center 3 1,286.9 0.0506 Tangentially-fired Wet Limestone

KS La Cygne 1 5,085.6 0.2022 Cyclone boiler Wet Limestone

KS La Cygne 2 16,243.4 0.7160 Dry bottom

MN Sherburne 

County 1 6,583.7 0.2635 Tangentially-fired Wet Limestone

MN Sherburne 

County 2 6,385.9 0.2631 Tangentially-fired Wet Limestone

MN Sherburne 

County 3 11,046.2 0.3317 Dry bottom Dry Lime FGD

MO Hawthorn 5A 2,016.0 0.0948 Dry bottom Dry Lime FGD

ND Stanton 1 2,188.6 0.5333 Dry bottom

ND Stanton 10 152.5 0.0693 Tangentially-fired Dry Lime FGD

OK Grand River 

Dam Authority 1 13,443.5 0.7313 Dry bottom N/A

OK Grand River 

Dam Authority 2 4,569.4 0.1978 Dry bottom Dry Lime FGD

OR Boardman 1SG 11,056.9 0.7018 Dry bottom N/A

WY Dave Johnston BW41 3,681.0 0.7657 Dry bottom N/A

WY Dave Johnston BW42 3,627.0 0.7736 Dry bottom N/A

WY Dave Johnston BW43 7,177.7 0.7588 Cell burner boiler N/A

WY Dave Johnston BW44 3,291.7 0.3293 Tangentially-fired Other

WY Neil Simpson II 1 555.77 0.1382 Dry bottom Dry Lime FGD

WY Wygen I 1 568.3 0.1306 Dry bottom Dry Lime FGD

WY Wyodak BW91 7,436.9 0.4694 Dry bottom Dry Lime FGD

Note: The lbs/MMBTU was figured by dividing the annual SO2tons values by the annual MMBTU values. NDEQ recognizes that 

short term periods (30 day) may show lower or high values.
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The table above shows has many sources not been able to meet the presumptive levels of BART 

(0.15 lb/MMBtu) for SO2 control over a 12-month period. Evaluating a 0.1 lb/MMBtu level

seemed to be a reasonable, yet aggressive level of control. Furthermore, while requiring a lower 

level of control, down to 0.02 lb/MMBtu would result in lower levels of emissions, it is likely 

more water and more lime would be required, increasing the costs of operating and possibly to 

install a scrubber to properly size for such levels of control. Therefore, it does not automatically 

follow that the cost effectiveness would make the project more reasonable. 

Comment 5: Water Resources

EPA commented that the BART determination should include a discussion as to whether stressed 

water resources are truly unique to the State of Nebraska, for purposes of visibility protection, 

and whether the visibility improvement meets the State‟s threshold of significance. EPA states 

that the arguments raised by NDEQ regarding water resources were more grounded in costs, not 

uniqueness or feasibility. 

Other commenters suggested that scrubbing was still cost effective despite the costs outlined in 

the proposed SIP. Other comments raised questions regarding the assumptions made in the 

impacts to the water resources of the state. 

The United States Forest Service (USFS) submitted comments regarding the statement made in 

the SIP about Nebraska‟s obligation to the Platte River Recovery Implementation Program 

(PRRIP). A review by the Nebraska Field office was done. The Field Office was asked to 

review and provide an opinion on: 1) the merit of NDEQ arguments and 2) any options for 

utilizing water while maintaining Endangered Species Act (ESA) protection. 

The USFS concluded that the arguments, statements about Nebraska water law, and the ensuing 

commitments Nebraska has under the PRRIP presented by Nebraska in the SIP are accurate and 

have merit, but may represent a worst-case scenario. They believe that the PRRIP inherently 

provides options to offset consumptive use that results in depletions to the river and jeopardizes 

endangered species. They believe that while, not inaccurate, the information tends to overstate 

implications of any new water use by NPPD. 

The USFS Field Office noted that achieving the ESA recovery objectives of the PRRIP will be a 

challenging endeavor and it is in the Service‟s interests to see Nebraska succeed. However, they 

believe that the figures and calculations used to describe offset needs and the comparison used 

when evaluating the offset versus other needs/obligations may portray a worst-case scenario. 

First, offset needs for the PRRIP and Integrated Management Plans (IMPs) may be able to be 

met concurrently or synergistically. They say the SIP fails to note that the majority of the 

remaining 50,000-70,000 Acre Feet (AF) of PRRIP 1st Increment water objective will likely be 

met by re-timing (re-regulating) existing water supply from times when target flows are 

exceeded to times of shortage (i.e. not solely by obtaining “new” water via conservation or 

acquisition of existing water rights). Further, any commitment of the parties to proceed toward

obtaining the estimates of water listed for a 2nd and 3rd Increment is speculative, at best. While

the Service has calculated an average annual shortage to targets of approximately 430,000 AF,

there is no certainty that future PRRIP increments will include an objective to achieve this

magnitude of reduction to shortages. If such commitments are made, undoubtedly the three states
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would each contribute; because the plan is silent on this, one might assume incorrectly that it 

would only be Nebraska‟s hardship to find the water.

The USFS goes on to say the example offset-driven acreage retirements provided by Twin Platte 

NRD likely do not represent the approach NPPD would take. The example uses an array of 

north/south sections immediately west of GGS so the stream depletion factors (SDF) vary widely 

(from 15 to 96%) and average 56%. There is no explanation or justification for this. Entities 

looking either to secure offsets (e.g. Central Platte NRD in their existing water banking program) 

or secure new supply for river flows (e.g. PRRIP as part of the 50,000-70,000 shortage reduction 

objective) are targeting irrigated land with higher SDFs. Presumably NPPD would use a similar 

approach, when possible, resulting in less acreage retired from irrigation. Accordingly, economic 

impacts from irrigated acreage retirements would be reduced proportionately. Finally, some of 

the statements about the economic impacts infer that NPPD would acquire the land in fee title, 

not just the water right for retirement (e.g. the $88,000,000 total cost for land acquisition).

The USFS suggests that the plan has not sufficiently considered all potential, feasible sources for 

this amount of water. It was suggested that the Nebraska parties could be taking the approach of 

“where there is a will there is a way”, similar to how new agricultural, commercial or industrial 

water users would investigate possible sources to accommodate their needs (e.g. ethanol plants). 

Response to Comment 5:

During discussions with EPA on the water resources issue, it was NDEQ‟s understanding that 

EPA wanted estimates on the „cost of water.‟ The SIP makes a good faith effort to do estimate 

such costs. However, all throughout the discussion on water, NDEQ clearly points out the 

moratorium that has been in place on the establishment of new uses of surface and groundwater 

in the Twin Platte Natural Resources District. The issue is whether it is appropriate to 

cause/contribute to another environmental problem for questionable benefit and high cost in 

another.

There is one ethanol plant in the Twin Platte NRD (TPNRD) that pre-dates the moratorium. 

Expansion plans for the plant were put on hold due, in part, to the difficulty in obtaining new 

water. The TPNRD is predominantly agricultural. The example provided regarding SDFs was 

that, an example to illustrate how not all wells would be considered equal for purposes of 

meeting offset requirements. If required to pursue the installation of a water intensive control 

measure such as dry or wet scrubbing, the actual strategy for NPPD would largely depend upon 

the willingness of irrigators in the area to sell land and their water rights. 

The NDEQ evaluated NPPDs water needs in terms of what dry and wet scrubbing would require 

and an industry average. Therefore, the offsets required by NPPD were not presented as a worst 

case scenario, but rather a „reasonable-case‟ scenario. 

It is critical to remember that NPPD GGS is located in an area where water is a real 

environmental issue. It is located in an area designated as over-appropriated. As demonstrated in 

the SIP, not all areas of Nebraska have an over-appropriated designation. NDEQ has an 

obligation to ensure that its decisions are made carefully so as to not exacerbate the issue. 
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Proper management of the water resources in Nebraska is an existing, unique environmental 

issue. The Natural Resource Districts (NRDs) are charged with water shed management and 

working with the State Department of Natural Resources to develop the integrated management 

plans to best respond to the local needs of their district. These 23 NRDs are unique to Nebraska 

and have been in existence since 1972. As explained in the proposed SIP, the area where GGS is 

located is “over-appropriated”. In 2004, the Nebraska Legislature enacted a law that mandated 

the State Nebraska Department of Natural Resources (NDNR) to make a determination of which

river basins, sub-basins or reaches are considered to be fully-appropriated or over-appropriated. 

The decision that a basin was “fully-appropriated” or “over-appropriated” would trigger a 

moratorium on new surface water and ground water uses and initiates a process with the affected 

local NRDs to develop an integrated management plan (IMP) to govern the apportionment of 

water resources in these basins. On September 15, 2004, the Director of NDNR issued an order 

designating portions of the North Platte NRD, South Platte NRD, Twin Platte NRD, Central 

Platte NRD and Tri-Basin NRD as “over-appropriated”. The GGS facility is located in the Twin 

Platte NRD within the area designated as “over-appropriated”. Most of these areas had already 

been determined to be “fully-appropriated” for surface water under the Nebraska system of prior 

appropriation of surface water rights and not available for new surface water appropriations. The 

2004 law mandated moratoriums on new water uses (surface and groundwater) to remain in 

effect unless removed as a result of implementation of an approved integrated management plan.

A basin is considered “fully-appropriated” if the current uses of hydrologically connected surface 

water and groundwater in a basin cause, or will cause in the reasonably foreseeable future, (a) the 

surface water to be insufficient to sustain over the long term the beneficial purposes for which 

the existing surface water appropriations were granted, (b) the stream flow to be insufficient to 

sustain over the long term the beneficial uses from wells constructed in aquifers dependent on 

recharge from the basin‟s river or stream, or (c) reduction in stream flow sufficient to cause 

Nebraska to be in noncompliance with an interstate compact or decree, formal state contract, or 

state or federal laws. Therefore, in “fully-appropriated” and “over-appropriated” basins, a plan 

for future water use must be put in place. The statutory definition of an “over-appropriated”

basin is very precise and related to conditions at a single point in time, July 16, 2004.

Areas that were designated as “over-appropriated” were required to develop a plan to reduce 

water use to the 1997 level of use within the next 10 years. In “over-appropriated” areas, the 

water demand already exceeds the current availability of water and the law requires steps be 

taken to mitigate the situation.

Therefore, there can be no new uses of water (surface and groundwater) without finding 

acceptable offsets in the area. The State and the Local agency responsible for water management 

must return the water shed to the appropriate balance, so that the availability of water meets the 

future demands for water. This responsibility goes beyond the agreements set forth in the Platte 

River Recovery Implementation Program. This system of water management is unique in the 

country and a responsible way to manage resources. To think of it in terms of air quality 

management, it is analogous to non-attainment. In a non-attainment area, before a new refinery 

or other large source of air pollution could be built, the source would be required to find offsets 

for pollution in that area before they would be issued a permit to build. Non-attainment areas do 

not exist everywhere, nor do they exist in all states. 
11

Comment 6: Cost Comparison to Other Facilities

EPA commented that NDEQ should ensure that GGS is compared to representative sources 

similar to GGS. EPA believes that the Kansas City Power & Light LaCygne and Westar Jeffrey 

Energy Center facilities are similar to GGS in that the visibility impact before control is similar 

and the cost to control is similar. 

Response to Comment 6:

Looking at Table 9.2 of the Kansas proposed SIP, NDEQ excerpted the following pre-control 

impacts from the KCP&L LaCygne and Westar Jeffrey Energy Center facilities:

Source CACR UPBU GRSA ROMO HEGL MING WIMO BADL WICA Total

Total Number of days during 2001-2003 with visibility impact >0.5 dv

KCP&L 

La Cygne 

Units 1 & 

2

204 249 17 21 278 233 142 46 38 1228

Westar 

Energy –

Jeffrey 

Units 1 & 2

150 161 27 28 182 158 165 82 55 1008

According to the Kansas proposed SIP; the lower than presumptive levels agreed to by KCP&L 

were done so to be consistent with an agreement with the Sierra Club and because of ongoing 

ozone issues in the Kansas City metro area. For the Westar Jeffrey Units 1 & 2, KDHE indicates 

that Westar plans to do this through rebuilding existing scrubbers on each unit. 

The predicted impacts from the NPPD & OPPD units on the 7 closest Class I areas were:

Source BADL GRSA HEGL MING ROCO WICA WIMO Total

Total Number of days during 2001-2003 with visibility impact >0.5 dv

NPPD GGS 

Unit 1 & 2 115 15 45 20 42 108 84 429

OPPD Unit 1 11 0 29 11 2 6 19 78

It is clear that the frequency of the impacts from the Nebraska facilities is less than half that of 

the Kansas facilities. Additionally, the circumstances for both of the Kansas sources are

different than the Nebraska sources. Neither of the Nebraska sources is located in an area with 

an ongoing ozone issue, nor is there an agreement in place for other purposes to meet certain 

levels of control. None of the 3 Nebraska units are currently fitted with a scrubber device to be 

rebuilt. Therefore, the Kansas facilities are not comparable to the Nebraska ones because 1) in 

the case of KCP&L, costs were being incurred anyway for purposes other than visibility; 2) in 

the case of Westar, costs of retrofitting and refiguring the source would be very different; 3) the 

frequency of impacts are much less for the Nebraska sources; and 4) Kansas does not apparently 

have an issue with availability of water in the area where these facilities are located. 
12

Comment 7: Visibility Improvement Calculations

EPA recommended that NDEQ consider calculating visibility improvement at multiple Class I 

areas. EPA noted that many other states had calculated visibility improvement over multiple 

Class I areas. 

Response to Comment 7:

See responses to previous comment related to $/dv. Nebraska confirmed the methodology used 

for $/dv was the same as that used by other states. See Table 10.19 of the SIP. 

Comment 8: Endangered Species

EPA commented that NDEQ should clarify and bolster its discussion related to endangered 

species if it intends to utilize the information for the SO2 BART determination. In its analysis, 

NDEQ suggested that low water availability could impact species such as piping plover, 

whooping crane, least tern and pallid sturgeon. In the proposed SIP, the NDEQ mentioned the 

Platte River Recovery Implementation Plan (PRRIP) reaching target water flows in the Platte 

River. EPA asked that NDEQ provide information on what the target flows are for the 

protection of these species and how increased consumptive water use by GGS would negatively 

impact meeting those target rates. EPA also noted that if endangered species are looked at, then 

the positive and negative impacts should be looked at, so such things as reduced mercury 

emissions should be looked at. 

Response to Comment 8:

Should EPA require the use of a water intensive device, a full endangered species evaluation and 

consultation with the Nebraska Game and Parks as well as the Federal Land Managers would 

need to occur in order to ascertain the impact to the Platte River as well as on the water resources 

of the State. Mercury is a known global issue and it is known to transport long distances. 

Mercury does naturally occur in environment, but is also emitted through the combustion of coal. 

According to EPA, current estimates are that less than half of all mercury deposition within the 

U.S. comes from U.S. sources. Coal-fired electric power plants account for about 50% of total 

U.S. manmade mercury emissions. While there may be some benefit to endangered species or 

habitats in other areas, evaluating the impacts of controls in an objective and quantitative manner 

to endangered species on the Platte River would be extremely difficult to measure and would not 

be practical. 

Comment 9: Other Non-Air Impacts

EPA commented that the NDEQ did not fully evaluate the energy and other non environmental 

impacts fully. EPA thinks it would be helpful to include in the analysis information regarding 

costs to build additional landfill facilities to handle the increased amounts of waste products and

the costs to build additional evaporator systems or disposal ponds. 

Response to Comment 9:

The impacts from energy were evaluated in the BART analysis.

The impacts due to whether landfills would need to be permitted and built were dependent upon 

pending decisions regarding whether the waste products could still be used for beneficial 

purposes and how this type of waste would be categorized. EPA had yet to decide the category 
13

of waste, which would impact the costs involved in disposal of waste. Regardless, there would 

be waste disposal costs. The costs involved would only result in an increase in operation and 

maintenance costs for the source. 

NDEQ did later evaluate DSI and included the costs involved. The life of the current landfill 

was expected to be greatly shortened due to the amount of sorbent involved to control sulfur. 

This evaluation was included. Again, to control SO2 in a non-water intensive manner resulted in 

another environmental issue related to waste disposal. 

Comment 10: Presumptive BART for Nebraska City Station (NCS 1)

EPA would like to affirm its belief that the NDEQ should consider at least the presumptive SO2

BART emission rate as appropriate for (NCS 1). EPA continues to assert that due to the unit‟s 

size, and based on EPA‟s interpretation of the Regional Haze Rule and Appendix Y to the 

Regional Haze Rule, that presumptive BART controls should be considered by the NDEQ for 

this unit and the basis for the determination fully explained. 

Response to Comment 10:

EPA has not presented any legal evidence to support their argument as to why NCS 1 should be a 

presumptive unit. The basis for the BART control decision is fully explained in the BART 

permit decision which is a part of the SIP. 

Comment 11: Emissions Inventory

EPA commented that NDEQ should address discrepancies in the SIP so that all data provided in 

its emission inventory summary are consistent with the data provided in the cited references or 

the NDEQ should explain any differences between the resource and the NDEQ‟s Regional Haze 

SIP. 

The discrepancies are noted below:

Comment 11a.

Response to 11a:

NDEQ agrees that the way the ammonia information was presented was not clear. The 

information related to ammonia emissions was taken from a different resource than the 

Refinement of CENRAP’s 2002 Emissions Inventories (August 31, 2005). There is still 

uncertainty with regard to ammonia emission inventory development. 
14

CENRAP commissioned a study by Sonoma Technology, Inc specifically for ammonia emission 

inventory development in the CENRAP state and tribal areas. It was a part of Appendix 8.3 of 

the proposed SIP (Research and Development of Ammonia Emission Inventories for the Central 

States Regional Air Planning Association; Final Report; STI-902501-2241-FR; October 30, 

2003). This report focuses on making enhancements to traditional ammonia emission inventory 

methodologies that were appropriate for the CENRAP area. Since this report looked more 

comprehensively at the ammonia inventory, and reported emissions overall that were higher for 

the state, that report was the basis for the ammonia values found in the proposed SIP, to be 

conservative. 

To make the information regarding NH3 more clear, NDEQ has created a new table detailing the 

ammonia inventory and has removed reference to ammonia from Table 8.1. The discussion 

regarding biogenic emissions and the contents of the Table 8.2 (now Table 8.3) remains 

unchanged. 

Summary of changes made to the tables below: NH3 Column Removed from Table 8.1. New

Table 8.2 created. Subsequent tables in Section 8 were renumbered. 

Table 8.1 2002 Nebraska Emissions Summary, by Pollutant and Source Category

Source Category VOC NOx SO2 PM10 PM2.5

Tons per Year

Point 1

7,274 58,619 73,487 13,105 4,638

Area 2

66,769 15,023 7,748 447,703 83,852

On-Road3

43,113 61,850 1,822 1,277 930

Non-Road4

24,882 119,568 11,011 7,491 6,785

Fires5

(Ag & 

Prescribed) 

3,204 679 268 5,057 3,956

Nebraska Total 145,242 255,739 94,336 474,633 100,161

 

1

Point Source Information taken from Table 2c Summary of Point Source Emissions by State and Pollutant Pechan, 

Refinement of CENRAP’s 2002 Emissions Inventories (August 31, 2005)

2 Area Source Information taken from Table 2b Summary of Area Source Emissions by State and Pollutant Pechan, 

Refinement of CENRAP’s 2002 Emissions Inventories (August 31, 2005)

3 On Road Information taken from Table 2e Summary of On Road Source Emissions by State and Pollutant Pechan, 

Refinement of CENRAP’s 2002 Emissions Inventories (August 31, 2005)

4 Non Road Information taken from Table 2d Summary of Non Road Source Emissions by State and Pollutant 

Pechan, Refinement of CENRAP’s 2002 Emissions Inventories (August 31, 2005)

5

Fire information taken from Table 2-1 and Table 2-2 of Research and Development of Planned Burning and 

Emission Inventories for the Central States Regional Air Planning Association (July 2004)
15

Table 8.2 2002 Nebraska Ammonia (NH3) Emissions Summary, by Source Category6

Source Category NH3

Tons per Year

Livestock 96,983

Fertilizer Application 64,443

Biogenics (Soil) 7,829

Point 800

On-Road 1,521

Non-Road 320

Miscellaneous 7,912

Nebraska Total 179,808

Comment 11 b. EPA believes the date for footnotes 2 – 6 for Table 8.1 is incorrect. The date in 

the proposed SIP is August 31, 2005; EPA believes the appropriate document date is April 28, 

2005. 

Response to Comment 11b:

The date and reference is correct. The document to which EPA is referring to is the 

Consolidation of Emissions Inventories Report which was also prepared by E.H. Pechan & 

Associates for CENRAP. The Consolidation of Emissions Inventories Report (April 28, 2005) 

was refined on August 31, 2005, with the Refinement of CENRAP’s 2002 Emissions Inventories. 

This document was contained in Appendix 8.3 of the proposed SIP. 

11c. EPA believes the VOC area source emissions noted in Table 8.1 are 3,197 tons per year less 

than what was referenced in the SIP. 

Response to Comment 11c:

Except as previously noted for ammonia (NH3), as can be seen from the Table 2b taken from the 

Refinement of CENRAP’s 2002 Emissions Inventories (August 31, 2005), the VOC emissions 

match those in the NDEQ proposed SIP. NDEQ also would like to note the typo in the EPA 

comments regarding the PM10 emissions. 

 

6 Ammonia information taken from Table B-1 Appendix B of Research and Development of Ammonia Emission 

Inventories for the Central States Regional Air Planning Association (October 2003)
16

Comment 11d. EPA was unable to verify the numbers for the “on-road” emissions in Table 8.1.

Response to Comment 11d:

Except as previously noted for ammonia (NH3), as can be seen from the Table 2e taken from the 

Refinement of CENRAP’s 2002 Emissions Inventories (August 31, 2005), the on-road emissions 

match those in the NDEQ proposed SIP. 
17

Comment 11e. EPA was unable to verify the numbers for the “nonroad” emissions in Table 8.1. 

Response to Comment 11e:

Except as previously noted for ammonia (NH3), as can be seen from the Table 2d taken from the 

Refinement of CENRAP’s 2002 Emissions Inventories (August 31, 2005), the non-road emissions 

match those in the NDEQ proposed SIP. 

Comment 11f. EPA noted that NDEQ should revise the SIP‟s Table 8.3 titled “2018 Nebraska 

Projected Emissions Summary, by Pollutant and Source Category (modeled)” and Table 8.4 

“2018 Percent Changes in Nebraska Emissions 2002 to 2018, By Pollutant and Source Category” 

to assure that the lack of SO2 control on NPPD and OPPD are properly accounted for. The 

United States Forest Service (USFS) also noted that the CENRAP Technical Document had 

presumed a certain level of SO2 reductions to be achieved through BART by 2018 (29%). The 

USFS believed that Chapter 8 should be revised to reflect the projected 2018 levels of SO2 with 

no EGU BART controls.

Response to Comment 11f:

NDEQ had included a discussion of the discrepancies between the predicted 2018 emissions and 

those to be achieved through the proposed SIP. To be clearer, NDEQ included tables showing 
18

what the EGU emissions have been for the last 10 years and what they are assumed to be in 2018 

as a result of all the measures discussed in the proposed SIP.

Actual SO2 Emissions from EGUs (Tons per Year)

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Gerald 

Gentleman 

Station

 

31,297 

 

32,152 

 

31,089 

 

32,035 

 

28,171 

 

31,135 

 

28,815 

 

31,362 

 

31,931 

 

29,741 

Whelan Energy 

Center

 

2,008 

 

2,007 

 

2,152 

 

2,352 

 

2,563 

 

2,330 

 

2,207 

 

2,229 

 

2,001 

 

2,301 

Lon D Wright 

Power Plant

 

1,088 

 

978 

 

1,017 

 

1,183 

 

1,332 

 

1,401 

 

1,708 

 

1,958 

 

1,250 

 

1,206 

Nebraska City 

Station

 

16,205 

 

12,820 

 

15,052 

 

15,593 

 

17,550 

 

14,994 

 

14,173 

 

17,498 

 

19,074 

 

14,296 

North Omaha 

Station

 

11,799 

 

11,509 

 

11,730 

 

16,125 

 

16,705 

 

14,315 

 

14,749 

 

15,012 

 

13,159 

 

10,515 

Platte

 

2,436 

 

2,250 

 

2,194 

 

2,158 

 

2,476 

 

2,637 

 

2,641 

 

3,086 

 

2,679 

 

2,365 

Sheldon

 

5,410 

 

5,624 

 

4,478 

 

4,768 

 

4,878 

 

4,403 

 

4,627 

 

4,552 

 

5,395 

 

3,758 

Total 70,243 67,340 67,712 74,214 73,675 71,215 68,920 75,697 75,489 64,182

Comment 12: Adequacy of the Long Term Strategy

The National Parks Conservation Association (NPCA) out of Knoxville, TN and Plains Justice 

(PJ) out of Billings, MT submitted a joint comment letter regarding the adequacy of the BART 

determinations and the Long Term Strategy in the proposed SIP. NPCA and PJ believe that 

NDEQ did not meet its responsibility for establishing a long term strategy to help achieve 

reasonable progress goals in Class I areas in other states. The United States Forest Service 

(USFS) also submitted comments stating similar concerns. The commenters note that in 

developing the Long-Term strategy, the State must consider all anthropogenic sources of 

visibility impairment and evaluate different emission reduction strategies beyond those 

prescribed by the BART provisions. At a minimum, the state must consider the following 

elements: 

Emission reductions due to ongoing air pollution control programs, including 

measures to address reasonably attributable visibility impairment; 

Measures to mitigate the impacts of construction activities; 

Emissions limitations and schedules for compliance to achieve the reasonable 

progress goal; 

Source retirement and replacement schedules; 

Smoke management techniques for agriculture and forestry management purposes 

including plans as currently exist within the State for these purposes; 
19

Enforceability of emission limitation s and control measures; and 

The anticipated net effect on visibility due to projected changes in point, area, and 

mobile emissions over the period addressed by the long-term strategy. 

Their concern is that during their review of Nebraska‟s proposed BART emission limits and 

controls, they believe that the state has not required emissions controls and limits that reflect 

BART for the state‟s BART-eligible sources. They are also concerned that the state has not 

required any source emission reductions or source retirements other than its proposed BART 

requirements to meet reasonable progress requirements in its Long-Term Strategy. They are 

concerned that the lack of reductions may impact the ability of nearby states to meet their Class I 

visibility goals. 

Response to Comment 12:

Each of the above elements were included and documented in the subsections of Section 11.3 of 

the SIP. 

Comment 13: Available Technologies or Upgrades were not Evaluated

The FLMs and NPCA commented that control options were not evaluated. In the instance of 

SO2, dry sorbent injection (DSI) was not evaluated for either facility. DSI does not require water, 

and can provide 50-80% emission reductions depending on the configuration of the facility and 

the system.

In addition, NDEQ‟s BART determinations did not consider upgrades to the existing PM control 

equipment at NCS (electrostatic precipitator (ESP)) or GGS (fabric filters). Each of these 

technologies could likely improve performance with upgrades, and this option should be 

evaluated as part of the BART determinations.

Response to Comment 13:

NDEQ did not evaluate upgrades for PM control because the attribution associated with PM 

from the sources was insignificant. NDEQ continues to believe that the current level of control 

is sufficient for purposes of visibility protection. 

NDEQ agrees that DSI should have been evaluated for GGS due to the potential for its impacts 

to the South Dakota Class I areas. NDEQ requested a BART analysis from NPPD and NDEQ 

conducted a subsequent evaluation of DSI, which has been included in Section 10.6.4 of the SIP.

Comment 14: Overemphasis of Incremental Costs

The NCPA commented that NDEQ overemphasized incremental costs when determining cost 

effectiveness. Cost effectiveness is the economic criterion used to determine whether a given 

control option has adverse economic impacts compared to controls at similar facilities. Cost, 

estimated using the total annual cost method, is measured in terms of annualized control costs, 

and cost effectiveness is measured in annual dollars per ton of pollutant removed. Two cost 

metrics can be considered: (1) total cost effectiveness and (2) incremental cost effectiveness. 

Total cost effectiveness, the metric most commonly used, is calculated by dividing annualized 

cost by the reduction in emissions. Incremental cost effectiveness compares the costs and 

emission performance with those of the next most stringent option. Incremental cost 

effectiveness should not be used to eliminate a top control option as BART if the total cost 
20

effectiveness is acceptable. As described in the NSR Manual, “undue focus on incremental cost 

effectiveness can give an impression that the cost of a control alternative is unreasonably high, 

when, in fact, the total cost effectiveness, in terms of dollars per total ton removed, is well within 

the normal range of acceptable...costs.” In this case, NDEQ highlights the incremental cost 

many times as a primary means of comparing one control technology to another. For instance, 

the incremental costs of adding SCR in addition to OFA/LNB is considered in all of the BART 

determinations. They believe the significant emphasis on incremental costs versus total costs for 

the technology is inappropriate. Incremental costs should be a secondary, not primary, 

consideration.

Response to Comment 14:

In the final preamble to the regional haze rules, EPA speaks to the use of incremental costs as a 

decision-making tool:

“We have finalized this section of the guidelines with some changes to how it was proposed. 

States have flexibility in how they calculate costs. We believe that the Control Cost Manual 

provides a good reference tool for cost calculations, but if there are elements or sources that are 

not addressed by the Control Cost Manual or there are additional cost methods that could be used, 

we believe that these could serve as useful supplemental information. 

In addition, the guidelines continue to include both average and incremental costs. We continue to 

believe that both average and incremental costs provide information useful for making control 

determinations. However, we believe that these techniques should not be misused. For example, a 

source may be faced with a choice between two available control devices, control A and control 

B, where control B achieves slightly greater emission reductions. The average cost (total annual 

cost/total annual emission reductions) for each may be deemed to be reasonable. However, the 

incremental cost (total annual cost A–B/total annual emission reductions A–B) of the additional 

emission reductions to be achieved by control B may be very great. In such an instance, it may be 

inappropriate to choose control B, based on its high incremental costs, even though its average 

cost may be considered reasonable. 

Finally, it is important to note that, while BART determinations are focused at individual sources, 

it is likely that in response to SIP requirements, States will be making BART determinations for 

many units in a subject source category all at the same time. In doing so, States are likely to 

compare costs across each source category as well as looking at costs for individual units in order 

to respond to SIP requirements in an efficient manner (from the State‟s perspective).”

NDEQ used both average and incremental costs consistent with the methods described above.

NDEQ did incorrectly use the term “incremental” in some places when average cost 

effectiveness was actually being evaluated. That was corrected in the SIP. 

Comment 15: Cost per Ton Metric is Down-played

The NCPA is concerned about how NDEQ determined cost effectiveness. Cost per ton of 

pollutant removed is a longstanding metric used to evaluate the cost-effectiveness of control 

technologies; in the regional haze context, cost per deciview can also be used to inform costeffectiveness evaluations, as a supplement to the cost per ton calculation. In this case, even 

without consideration of inflated cost estimates or discounted control efficiencies the cost per 

ton, both total and incremental, of all evaluated – and rejected – technologies is well within the 

range of cost-effectiveness of other BART determinations. Much higher measures of cost-
21

effectiveness than those rejected by the state have been used in both BART analyses and rulemaking instances, over $10,000/ton in some instances. NDEQ itself notes that $2,500 –

2,700/ton is “reasonable”; all of the total costs are at or below this level.

Response to Comment 15:

Cost per ton of pollutant removed is the metric used in the Prevention of Significant 

Deterioration Program when making a decision on the Best Available Control Technology for 

new sources. This program is designed to improve visibility. The decision is for the control 

technology on existing sources. In the Regional Haze Rules, and as a result of American Corn 

Growers vs. EPA, visibility improvement must be considered when making such decisions. In 

the final rules, EPA provided for $/dv as a metric States could use to evaluate cost effectiveness. 

The $/dv metric couples the visibility improvement to the investment, just as the $/ton removed 

does in the PSD program. NDEQ evaluated cost effectiveness as one of the metrics in the 

overall analysis. As discussed in previous comments, the State has discretion as to the weight to 

give each metric. NDEQ evaluated the $/dv metric consistent with the evaluation conducted by 

other States.

Comment 16: SCR Costs are Overestimated

The FLMs commented that the cost estimates are missing significant amounts of information that 

is necessary for the public or other agencies to be able to thoroughly review and comment on 

them. For instance, unsubstantiated vendor quotes underlie a large portion of the cost estimates. 

Nonetheless, it is clear that some of the relied on costs are overestimated. The capital costs for a 

retrofit of SCR at GGS Units 1 and 2, as reported on a $/kw basis, are significantly higher than 

those found by several industry studies of SCR installations. Those reports found a range of 

installed costs between $83 – 300/kw, the highest of which were highly complex retrofits with 

severe space constraints. 

Response to Comment 16:

Costs to retrofit an existing facility will vary widely from site to site depending upon the 

individual circumstances. The cost information provided by NPPD and OPPD was determined to 

be reasonable. In the case of NPPD there are severe space constraints on-site which would 

require unique retrofits causing an escalation in costs. According to a 2007 analysis conducted 

for LADCO, actual retrofits for SO2 and NOx controls were costing more than the estimates 

provided by EPA and other regulators. Actual FGD costs were about $200/kw higher and SCR 

costs were $25-$45/kw higher. 

The primary reason for not requiring SCR for control was due to the incremental effectiveness. 

The primary reasons for not requiring SO2 control for OPPD was the lack of significant visibility 

improvement as well as the cost effectiveness. The primary reasons for not requiring SO2 control 

for NPPD was due to other non-air quality impacts and the resulting effect on the environment as 

well as the cost effectiveness. 

Comment 17: CALPUFF versus CAMx

The USFS commented that in Section 10.2, Nebraska described the assistance received from 

EPA Region 7 with regard to modeling. The USFS justified how one may use CAMx modeling 
22

to inform visibility decision making in light of the framework provided by Appendix Y 

(Regional Haze Rules) and Appendix W (Guideline on Air Quality Models). 

Response to Comment 17:

The US EPA speaks to the issue of using CALPUFF versus a regional model such as CAMx in 

the final regional haze rule: 

“Theoretically, the CALPUFF chemistry simulations, in total, may lead to model predictions that 

are generally overestimated at distances downwind of 200 km. Again, States can make 

judgments concerning the conservativeness or overestimation, if any, of the results. The use of 

other models and techniques to estimate if a source causes or contributes to visibility impairment 

may be considered by the State, and the BART guidelines preserve a State‟s ability to use other 

models. Regional scale photochemical grid models may have merit, but such models have been 

designed to assess cumulative impacts, not impacts from individual sources. Such models are 

very resource intensive and time consuming relative to CALPUFF, but States may consider their 

use for SIP development in the future as they are adapted and demonstrated to be appropriate for 

single source applications. However, to date, regional models have not been evaluated for single 

source applications. Their use may be more appropriate in the cumulative modeling options 

discussed above.”

It was for the above reasons that NDEQ chose to use CALPUFF as a tool for decision-making 

purposes.

Comment 18: Emissions Impact Potential for NPPD on Nearby Class I Areas

The USFS provided information regarding the potential for emissions from NPPD GGS to 

impact Class I areas in adjacent states, particularly in South Dakota. The USFS believes that 

NPPD GGS plays a central role in haze formation at Badlands National Park and Wind Cave 

National Park for both nitrate and sulfates. The USFS provided CALPUFF and CAMx modeling 

results showing that NPPD GGS impacts for 2002 were greater than 0.5 dv on 15% of the days 

and 23% of the days, respectively. 

Response to Comment 18:

NDEQ addressed the potential for sulfates and nitrates from Nebraska sources to contribute to 

Class I area visibility in Section 11.2 of the proposed SIP. NDEQ believes that nitrates are a 

greater contributor than sulfates from Nebraska, and that the reductions in visibility due to NOx 

control will benefit the South Dakota Class I areas. 

Comment 19: Linkage Between PSD and Visibility Days

The USFS requested that NDEQ recognize the link between the Prevention of Significant 

Deterioration Program and the need to protect visibility. The NPS and FWS also requested a 

discussion about how the visibility improvement goals under the regional haze rule are 

incorporated in Nebraska‟s Prevention of Significant Deterioration program. 

Response to Comment 19:

NDEQ addressed the linkage between the PSD (NSR) program and the need to protect visibility 

in Section 11.3.2 of the proposed SIP.
23

Comment 20: Smoke Management Plans (SMPs)

The USFS requested that Nebraska not include a smoke management plan as an appendix to the 

Regional Haze SIP because in the event that the SMP is modified, a SIP revision may be 

necessary. 

Response to Comment 20:

NDEQ addressed the issue of smoke management under Section 11.3.4 of the proposed SIP. 

Comment 21: Reasonable Further Progress

The National Park Service and Fish and Wildlife Service provided comments regarding their 

concerns that they do not believe Nebraska met the requirement to address enforceable 

limitations, compliance schedules, and other measures necessary to achieve reasonable progress 

goals established by States with Class I areas. They point to information in the proposed SIP 

which shows that point source SO2 emissions account for 78% of total SO2 emissions in 

Nebraska‟s 2002 inventory of which, electric generating units (EGU) account for 92% of point 

source SO2 emissions. Section 8.3.1.3 indicates that the 2018 inventory assumes significant 

reductions in SO2 from electric generating units based on assumptions of the Integrated Planning 

Model. NDEQ does not document any actual SO2 controls. They infer that no reductions in SO2

emissions from point sources are expected and that, based on Tables 8.1 and 8.3, SO2 emissions 

from Nebraska in 2018 are underestimated by 21,218 tons, or 25% in the CENRAP and WRAP 

2018 modeling. They request that Nebraska require SO2 controls consistent with emission 

assumptions.

Response to Comment 21:

NDEQ recognized up front in the discussion on the emissions inventory in Section 8 of the 

proposed SIP that there was a discrepancy between what was modeled for 2018 and what the 

proposed SIP would require. To make it clearer, additional discussion has been added to Section 

8. 

Comment 22: Emissions Inventory for EGUs

The NPS and FWS requested that NDEQ include a description of the emissions for the BART 

eligible units. Appendix 10.1 indicates that Gerald Gentleman Units 1 and 2 combined have 

potential SO2 emissions of 79,200 tons/year and Nebraska City Unit 1 has potential SO2

emissions of 45,696 tons/year. They asked that NDEQ confirm and provide the actual annual 

SO2 emissions from the 2002 CENRAP inventory for these three units, similar to the nitrogen 

oxide (NOx) information in Table 8.5.

Response to Comment 22:

The proposed SIP directs the reader where to find a complete description of all BART eligible 

units. The complete actual inventories for all EGUs in the state (coal and natural gas fired) are 

included in Section 8 for the last 10 years. A projection for 2018 was included with an 

explanation. 

Comment 23: Five Factor Analysis

The NPS and FWS requested that NDEQ provide in Chapter 10, a summary of the five factor 

analyses for Gerald Gentleman and for Nebraska City. They suggested BART analyses be 
24

summarized in the SIP Narrative and reference the appropriate appendices for further 

information. 

Step 1: Identify the available retrofit technologies for SO2 and NOx. For SO2 this should 

include lime spray dryer and dry sorbent injection as control options with lower water 

use requirements than wet flue gas desulfurization. For NOx this should include 

selective non-catalytic reduction (SNCR) technology in addition to selective catalytic 

reduction (SCR). 

Step 2: Eliminate technically infeasible options. 

Step 3: Evaluate effectiveness of control options.

Step 4: Evaluate impacts and document results. 

Step 5: Select Best Available Retrofit Control 

Response to Comment 23:

Brief summaries are included as requested. Dry Sorbent injection was added. Dry and wet 

scrubbing were already evaluated, as well as SNCR and SCR. Full summaries are included in the 

Appendices for Section 10.

Comment 24: Controls for Nebraska City

The NPS and FWS believe that presumptive controls should be required at Nebraska City 

Station. They believe that the information EPA Region 7 provided to Nebraska in a letter dated 

January 23, 2009, required that the total plant capacity (BART plus non-BART units) be used to 

determine if an Electric Generating Unit (EGU) is greater than 750 MW and that any units in 

existence at the time of the BART determination are to be included in the total plant capacity. 

They note a typo in the text in Section 10.5 incorrectly referring to Unit 2 as BART eligible. The 

NPS and FWS asked for the MW capacity of Units 1 and 2. They believe it is unacceptable for 

Nebraska to provide the legal requirements for presumptive controls rather than discussing the 

BART analysis and visibility impacts from Unit 1. 

The Federal Land Management agencies believe that SO2 control on Unit 1 is cost effective and 

reasonable. They are concerned that NDEQ dismissed control due to high $/dv improvement for 

one Class I area. They, like others, believe that it is appropriate to consider both the degree of 

visibility improvement in a given Class I area as well as the cumulative effects of improving 

visibility across all of the Class I areas affected. They argue that if emissions from Nebraska 

City Station are reduced, the benefits will be spread well beyond only the most impacted Class I 

area, and this must be accounted for. 

The NPS and FWS recommended that OPPD obtain current cost estimates for all alternatives 

rather than simply scaling 2003 information to the present. Current vendor cost estimates may 

be quite different and the errors of scaling could be large. In an effort to make OPPD‟s results 

for all control alternatives comparable to the universe of other companies‟ BART 

determinations, cost calculations based on use of the most recent OAQPS Control Cost Manual 

should be performed. They believe the $/kw are too high. 

The FLMs suggest that OPPD consider upgrades/improved operation as a BART alternative for 

PM. 
25

The NPS and FWS express concerns that in OPPD‟s BART Analysis document, OPPD argues 

that certain visibility improvements are “well below the minimum perceptible dv change”. The 

FLMs believe it is incorrect to dismiss a control strategy on the basis that the resulting 

improvement is not perceptible or significant. 

Response to Comment 24:

See responses to comments 2, 10 and 13. Also see the Response to the OPPD BART Permit 

comments in Appendix 10.8.

Comment 25: Controls for Gerald Gentleman

The FLMs do not agree with the BART determination of no SO2 controls for Gerald Gentleman. 

Was dry sorbent injection considered? If not, why not? Nebraska provides an elaborate 

justification that limited water availability prohibits the application of wet flue gas 

desulfurization (FGD) at Gerald Gentleman without discussing the viable alternatives that are 

being used in western states. The economic factors influencing the economy of Nebraska are 

much greater than the possible retirement of irrigated acreage to obtain water rights for the 

power plant. 

The NPS and FWS provided substantial comment on the costs of controls provided by NPPD. 

Their main concerns were with the methodology utilized and their belief that the retrofit would 

not involve severe space constraints. In total, they believe the costs are overestimated. 

The FLMs expressed concern that NDEQ did not take into account the potential improvements to 

visibility in the other Class I areas where GGS is also causing or contributing to visibility 

impairment. They argue that if emissions from the BART source are reduced, the benefits will be 

spread well beyond only the most impacted Class I area, and this must be accounted for. While 

NDEQ presented data describing improvements to visibility at Badlands NP that would result 

from the various control scenarios it investigated, the FLMs would like an explanation of how 

NDEQ incorporated this information on impacts upon all Class I areas into its BART decision. 

The NPS and FWS expressed concern over the analysis of SCR. They believe that NDEQ 

should evaluate the cost-effectiveness of SCR in combination with combustion controls rather 

than evaluating the addition of SCR to LNB/OFA as an incremental cost. The FLMs provide 

data to support their position that NDEQ should determine SCR with LNB/OFA BART for 

NPPD GGS. They believe the cost information provided by NPPD overstates the costs involved 

for installation of an SCR system. They argue that the LNB/OFA burners currently on one of the 

GGS units were not in existence at the time the BART Guidelines were finalized and therefore 

cannot be separated from the LNB/OFA+SCR system evaluation. Likewise, with SO2 control, 

the FLMs present many of the same concerns over the costs. They believe the $/kw are too high. 

The FLMs also urge that NDEQ require emission limits significantly lower than the presumptive 

levels for both NOx and SO2. 

Response to Comment 25:

See the responses to comments 2, 5, 6, 13 and 16. Also see the Response to the NPPD BART 

Permit comments and Final Fact Sheet found in Appendix 10.8.
26

Comment 26: Baseline, Current, and Natural Visibility Conditions

The FLMs requested a summary of baseline conditions at key Class I areas (e.g. Badlands, 

Hercules Glade) impacted by Nebraska emissions to establish the relative contributions of 

pollutant species, seasonal trends in pollutant contributions, and priority for emissions controls. 

Because the Class I areas are geographically distant, the priority for emissions controls may 

differ among the Class I areas. 

Response to Comment 26:

Nebraska has no Class I Federal areas within its borders. Therefore, Nebraska does not have an 

obligation to include this information in its SIP.

Comment 27: Monitoring Strategy

The FLM noted that measurements at IMPROVE sites and from special studies are discussed but 

no results are presented. 

Response to Comment 27:

Nebraska has no Class I Federal areas within its borders. Therefore, Nebraska does not have an 

obligation to include this information in its SIP. While results were not presented, discussion 

was included as to how the information was used by CENRAP. 

Comment 28: Emissions Inventory

The FLMs asked for additional discussion on ammonia (NH3) emissions in Nebraska in 2002. 

The FLMs disagree with ignoring NH3 as a contributing pollutant, even if it is not a criteria 

pollutant. They also asked for a discussion of the change in NH3 in 2018 in Table 8.3 and Section 

8.3.1.5. 

The FLMs asked for additional information on the 2018 projections to provide better explanation 

of the source categories contributing to point source emissions of SO2 and NOx. This 

information was not presented in either Appendix 8.2 (SMOKE reports in Microsoft Access) or 

Appendix 9.1 (ENVIRON technical report). This information is critical to supporting an 

adequate reasonable progress analysis. 

Response to Comment 28:

See response to comment 11.

Comment 29: BART

The FLMs asked that NDEQ include the CENRAP BART Modeling Protocol in the Appendices 

as it has been referenced in the BART Modeling Protocol for Gerald Gentleman and Nebraska 

City. 

Response to Comment 29:

The CENRAP BART modeling protocol is a reference. It has been added as an Appendix 9.2. 

Comment 30: Reasonable Progress/Long Term Strategy

The FLMs stated that Table 11.1 reports the net improvement in Light Extinction at neighboring 

Class I areas based on source apportionment modeling and what appear to be incorrect 
27

assumptions for SO2 emissions in Nebraska. The FLMs conclude that if the emissions 

assumptions are invalid, Nebraska‟s demonstration of reasonable progress is also invalid. 

The FLMs noted that in Section 11.2: Colorado mentions in its regional haze SIP consultation 

with Nebraska on the BART determination for Gerald Gentleman due to the plant‟s impact to 

Rocky Mountain National Park, but Nebraska does not include Colorado in its summary. 

The NPS and FWS note that in South Dakota‟s SIP, a 36% reduction in Nebraska SO2 emissions 

were used in setting reasonable progress goals for Badlands and Wind Cave National Parks. 

They calculated this to be 23,623 tons lower than what a no EGU SO2 controls in Nebraska SIP 

would garnish. 

The NPS and FWS requested that Nebraska re-evaluate what reductions are necessary to support 

the reasonable progress goals of neighboring states. The regional haze rule requires that the 

State include in its long term strategy all measures needed to achieve its apportionment of 

emission reductions and to identify all anthropogenic sources of visibility impairment considered 

in developing the long term strategy. They are concerned about Nebraska demonstrating that its 

emissions sources are being controlled and that reasonable progress is being met in reducing 

anthropogenic emissions.

Response to Comment 30:

See response to previous comments 12, 18, 21 and 22. The FLMs are correct that Colorado did 

provide comments on the GGS BART permit as well as the proposed SIP. Section 11.2 has been 

revised accordingly. 

Comment 31: Water Demands on Nebraska

The Twin Platte Natural Resources District (TPNRD) provided comments regarding the impact 

SO2 controls may have on TPNRD. The TPNRD agreed with the May 11, 2011 Fact Sheet 

(BART & PSD Analysis For the NPPD GGS) prepared by the Nebraska Department of 

Environmental Quality (NDEQ), which states that there is a significant non-air quality 

environmental impact for NPPD regarding water use, if either Wet or Dry Flue Gas 

Desulfurization (FGD) control technology is required.

The TPNRD stated that the Platte River Basin in western Nebraska has been designated by the 

Nebraska Department of Natural Resources (NDNR) as Over Appropriated, as required by 

Nebraska law enacted in 2004. The designation that the Platte River Basin is Over Appropriated 

required the NE Department of Natural Resources (NDNR) and the TPNRD to jointly develop an 

Integrated Management Plan (IMP). The IMP provides that there are no new depletions to 

ground water or surface water, that the Platte River must be returned to 1997 flows within the 

first ten years following approval of the IMP which occurred in 2008, and the Platte River Basin 

in western Nebraska ultimately must be returned to Fully Appropriated. To accomplish the 

requirements of the IMP, since 2004, there can be no new depletions of water within the 

TPNRD, and the TPNRD must provide offset water to the Platte River in the amount of 7,700 

acre-feet within the first ten years and a yet undetermined amount of offset water to the Platte 

River to reach Fully Appropriated. 
28

They concluded that finding offset water in an area that is Over Appropriated is very difficult 

and very expensive, as described in the May 11, 2010 NE DEQ Fact Sheet. If NPPD were to 

have to find water for either Wet or Dry FGD, they would be competing with the TPNRD and 

the other Natural Resources Districts within the Platte River Basin.

Response to Comment 31:

NDEQ appreciates the feedback from the Twin Platte NRD and agrees with the conclusions.