United States Department of the Interior NATIONAL PARK SERVICE Carlsbad Caverns National Park 3225 National Parks Highway IN REPLY REFER TO: Carlsbad, NM 88220 505-785-2232 TRANSMITTED VIA ELECTRONIC MAIL - NO HARDCOPY TO FOLLOW August 29, 2016 Memorandum To: Paul Murphy, Project Lead, Bureau of Land Management, Carlsbad Field Of?ce From: Doug Neighbor, Superintendent, Carlsbad Caverns National Park Subject: National Park Service Comments on the Chevron U.S.A., Inc. Hayhurst Master DeveIOpment Plan, Environmental Assessment DOI-BLM-NM-P020-2016-1434-EA The National Park Service has reviewed the referenced Environmental Assessment (EA) completed in support of the Chevron U.S.A., Inc. Hayhurst Master Development Plan (MDP). We appreciate the opportunity to comment on this MDP and discuss the potential impacts to park resources in Carlsbad Caverns Nation Park. The western boundary of the project area is located approximately 17 km from the eastern boundary of Carlsbad Caverns National Park (NP), a Clean Air Act Class I area administered by the NPS. As such, we have a number of comments regarding the potential air resource impacts to resources in Carlsbad Caverns NP as a result of this proposed development. We also have a number of concerns associated with cumulative night sky impacts to this park. In summary: 0 The NPS concludes that as prOposed, the project will result in signi?cant adverse effects to the desert ecosystems in Carlsbad Caverns NP due to excess nitrogen deposition (associated with 744 TPY additional emissions from oil and gas drilling and production equipment). As a result, we do not believe the project impacts are congruent with the issuance of a Finding of No Significant Impact. 0 We would like to explore emission mitigation options that may be feasible for this project to eliminate the signi?cant impacts to park resources. I We have signi?cant concerns regarding the cumulative impacts to night skies. We recommend the BLM implement additional BMPs to further mitigate existing and future impacts to night skies in Carlsbad Caverns NP. I In the future, we recommend that similar projects, particularly ones in proximity to NFS areas followr the collaborative process outlined in the Bill I Air Quality Memorandum of Understanding Among the LLS. Department of Agriculture, LLB. Department of the Interior and the U.S. Environmental Protection Agency Regarding Air Quality Analyses and Mitigation for Federal Gil and Gas Decisions Through the National Environmental Policy Act Process'. These comments are discussed in greater detail below. Background Carlsbad Caverns National Park is located in the Guadalupe Mountains, a mountain range that extends from west Texas into southeastern New Mexico, and is situated in the northern portion ofthe Chihuahuan Desert, the largest and wettest of the North American deserts. Carlsbad Caverns was set aside as a unit of the National Park System in port to preserve and protect the Chihuahuan Desert ecosystem it contains. In addition, other primary porposes of the park are to preserve and protect the world?class cave resources and portions ofthe Captain Reef, which provides opportunity to experience extraordinary scenic vistas (Carlsbad Caverns General Management Plan, 1996]. Elevations within the park rise from 3,595 feet {1395 meters) in the lowlands to 15,53] feet (1,93? meters] atop the escarpment, with scattered woodlands in the higher elevations and a variety of grassland and desert shrubland habitats covering the remaining majority of the park. The park spans two different ccoregions: the ?Temperate Sierras? and the ?North American Deserts." Much of the park?s backcountry is designated Wilderness, over acres, providing outstanding opportunities for solitude and primitive recreation. As such, the park provides a diverse and remote range ofhabitats. [n 1995, the park became a Heritage Site. demonstrating the outstanding universal value of the park?s natural resources? The park is also a designated Ciass 1 area under the Clean Air Act, giving the federal [and manager (FLM) for these areas an ?affirmative responsibility" to protect the air quality and AQRVs in this park from the deleterious effects of air pollution. Nitrogen Degosition Imgnettr Based on a CALPUFF modeling analysis using one year of meteorological data, the MDP would result in annual nitrogen deposition of?illBE?il?l?g kgfhaiyr over a ten year period. This nvaitahle al: Uindexr I'm. 1 in considering inclusion ofCarlsbad Caverns NP as a world heritage site. the UNEECD advisory body sum mary notes: ?Vegetation cont munitics range ?'om desert to coniferous forest- Some Bil-t} plant species have been identi?ed. of which th me are internationally threatened: Snead pincushion cactus, Lee pincushion cactus and Lloyd?s hedgehog cactus. The faunal inventory includes ?d mammals, 331 bird and 44 herpetofauna species. The caves are noted for their migratory bat species, especially the Mexican free-tailed bat whose population is estimated at one million individuals. 1 tiarious species of fungi and bacteria growing in the caves are of particular scienti?c and medical interest." The advisory bod also identi?ed potential oil and gas development along the park?s boundaries as a ?serious threat" to the site. amount of annual deposition is roughly talc-229% oi' the NPS Deposition Analysis Threshold a threshold used to determine signi?cancctinsigni?cance of new sources oliernissions. n?er year 1 of the project, the deposition would drop to kgthatyr for the remaining lite of the project [representing production emissions alone), a level which is just over the NPS DAT. We have concluded that this constitutes a signi?cant adverse effect to park resources based on the current modeledtmonitored estimates of' cumulative annual deposition loading in Carlsbad Caverns NP and the presence of vegetation types within park which published science indicates are highly sensitive to excess nitrogen deposition, the magnitude of predicted additional nitrogen deposition as a result of the project emissions, {Ii} the other site- speei?c factors outlined under Contexthriteriofor Evaluating a DATErceeo'onee? below (cg, the proximity of the project to the park, the duration of the impact). As discussed here and elsewhere, we recommend NCix mitigation is necessaryr to address the signi?cant impacts. Pork Ecosystems oner Current Conditions The Chihuahuan Desert is the most biologically diverse desert in the Hemisphere and one of the most diverse in the world. Carlsbad Caverns is ecologically signi?cant in that it contains one ofthejew protected portions ofthe northern Desert ecosystem (6MP, i995) Many plant and animal species located in the part: are at the limits oftheir geographic range and the park?s biodiversity Is quite high. However, these systems are threatened by external stresses, including nitrogen deposition. Woodland, and grassland vegetation types in the North American Deserts Ecoregion, such as those found in Carlsbad Caverns, are known to be highly sensitive to deposition. Nitrogen deposition in these ecosystems may increase the presence ofnon?native plant species and alter ?re regimes. Critical loads are a tool established by scientists to assist the NPS and other land managers in determining annual levels of cumulative deposition below which park ecosystems would be protected from undesirable change or damage. Critical loads are cumulative deposition thresholds speci?cally linked to the plant and animal communities or species present in a given area or ecosystem indicators). A critical load is de?ned ?the quantitative estimate ot?an exposure to one or more pollutants below which signi?cant harmful effects on speci?ed sensitive elements of the environment do not occur according to present knowledge.? The current estimated annual level of total nitrogen deposition at Carlsbad Caverns National Park (CAVFJ ranges from 2. legihat'yr to 3. 5 ltgl'hat'yr,4 which is at orjust over the minimum critical load for increases in invasive and lichen community shifts {31} kgr?hatyr) in these ecorcgionsi. When current deposition levels are at or near the critical load, it indicates that negative ecosystem changes may already be occurring in the park. Consequently, the NPS is concerned about additional deposition inputs. i-[erhaceous vegetation critical loads in arid areas are generally based on the potential spread of invasive grass Species due to excess nitrogen. Brornns rtthens {red brome}, and Mp?wnmv?ilgmessneuw National Atmospheric Elli-'1. I'o-tnl Deposltton Maps. {version}. It Il:tp ti'parlpL 1.111., palm. [accessed I11tp; ttutvw mumps. icnll- ?gs-reg 3 Avenafatua (Wild Oats), are two species of invasive grass found within Carlsbad Caverns NP. Research studies have demonstrated that both species grow faster under conditions of excess nitrogen deposition. Fertilization studies to show change through arti?cially increasing levels of and gradient studies show change across the landscape as deposition increases (Brooks 2003, Allen et al. 2009, Rao et al. 2011). Research at Joshua Tree National Park and in the Mojave Desert has shown that at a deposition rate of 3.0 ng/ha/yr and above, the excess nitrogen can stimulate additional biomass growth from B. rubens suf?ciently to increase ?re risk through the desert ecosystem which is not adapted to large wild?res (Rao et al. 2010). The growth of invasive grasses also has a direct impact on the richness and diversity of native vegetation (Brooks 2000, Allen et a1. 2009competition for space and nutrients. Maintaining native plants and natural biodiversity is important when considering the park?s status as a Class I area, maintaining the wilderness character of backcountry areas designated as wilderness (which are dif?cult to treat for non-native invasives) and in maintaining habitat that is crucial to the species diversity which is noted in the park?s initial consideration as a UNESCO World Heritage site. Additionally, the invasive grass Cenchrus ciliaris, buffel grass, is present in counties adjacent to CAVE, but has yet to be found within the park boundaries. C. ciliaris is an aggressive invader and has been shown to have a positive growth response to increased soil N, allowing it to spread faster into disturbed areas (Lyons et al. 2012, Marshall et al. 2012) when excess nitrogen deposition occurs. Finally, increased atmospheric concentration and deposition can have a toxic effect on sensitive lichen species accustomed to low nitrogen levels, and lead to an increase in species of weedy lichens adapted to higher nitrogen levels (Pardo et al. 2011, Root et al. 2013). The change in lichen composition removes and/or provides lower quality of food and nesting material for small mammals and birds that inhabit the region. This is important as the park provides habitat for numerous bird species. The park?s draft Natural Resource Condition Assessment states: ?The unique ecosystems and physical formations in Carlsbad Caverns NP provide bird species with a wealth of habitat types and food sources. While the park is most notable for its expansive cave formations and habitats, a habitat type that is heavily utilized by cave swallows (Petrochelidon?tlva?, the park is also home to several stretches of grassland habitats as well as the desert riparian oasis in the Rattlesnake Springs Unit. Of particular note are the rugged and remote high elevation mesic vegetation communities in Carlsbad Caverns NP (West 2012). The park has con?rmed the presence of 362 bird species within the park and another ?ve species have been identi?ed as probably occurring in the park (NPS 2016). Among the con?rmed Species are several birds designated as species of concern by at least one agency. Four bird species in park are listed under the Endangered Species Act (BSA) as either threatened or endangered: the southwestern willow ?ycatcher (endangered), yellow?billed cuckoo (Coccyzus americanus; threatened), lesser prairie chicken (threatened), and the Mexican spotted owl (Strix occidentalis lucida; threatened). The Rattlesnake Springs area of CAVE is of particular importance to several bird species of conservation concern, especially riparian obligate Species such as the Bell?s vireo (Vireo bellii; state-threatened species) and the yellow?billed cuckoo. The southwestern willow ?ycatcher has also been observed in this habitat type, and may potentially breed there {Powell assay." (2) Deposition Doc to Project Emissions IGiven the proximity of tlte proposed development area to Carlsbad Caverns NP and the magnitude of tlte anticipated annual NU): emissions, the modeled deposition from this proposal significantly exceeds the NPS DAT, indicating that this project may exacerbate existing deposition impacts to park ecosystems resulting from an estimated of the critical load. It is important to note that the DAT is a tool for evaluating the signi?cance of a project?s contribution to deposition in a given area. A project contribution to deposition that is below the DAT is considered insignificant. A project contribution to deposition that is above the DAT is scrutinised more closely. (3) Evaluating a DA Exceedonce Factors such as the magnitude of the enceedance, any proposed mitigation, the rcsource(s} impacted and their significance to park protection, regional changes in emissions and other considerations speci?c to the area impacted are all considered when determining whether an enceedance of the DAT is adverse'i. Speci?cally, in this circumstance: I Regional air quality modeling analyses {including the recently completed Carlsbad analysis] predict that air quality is unlikely to improve in near? term within the life of this project) and that cumulatively, oil and gas development makes a significant contribution to air quality and AQRV impacts in this region. I As demonstrated above, the HPS believes that the ecosystems in Carlsbad Caverns NP may he at a tipping point for harmful effects associated with nitrogen deposition it is estimated that deposition is at the CL value for this region). I Carlsbad Caverns is ecologically signi?cant in that it contains one oftne?-rw protected portions oftnc northern Cninnonnon Desert ecosystem (UMP, 1996). As such, ecological impacts from deposition in this park are given signi?cant weigh. I The magnitude of the annual DAT esceedances due to MDPwassociated activities are signi?cant, the predicted project?caused deposition is almost two and a halftimes the DAT threshold. in addition, as described below, if any potential N?s sources are missing front the inventory, the deposition impacts may be underestimated. I The duration of DAT is projected to last many years [at least a decade or more) '5 For more information on how the MPH cvaitlatcs deposition impacts, see the Federal Land Managers' Interagcney Guidance for Nitrogen and Sulfur Deposition Analyses {November ll, Natural Resource Report Jill 4165, available at: tinidancc 2t}l Let! The proximity of the project to the park. In this circumstance, considering all of these factors, we recommend that additional mitigations are necessary to avoid signi?cant impacts associated with nitrogen deposition in Carlsbad Caverns NP from activities approved under this EA. N0x Emissions Mitigation Equipment associated with the drilling, completion and production operations are anticipated to emit 744 TPY of in the maximum emission year, which is estimated to be project year 9. Of these NOX emissions, roughly 70% are attributable to the drilling operations (including drilling and completion), 15.5% are attributable to the compressors (7 total) and roughly 13.7% are attributable to the separator heaters located at centralized tank batteries (the remainder is other miscellaneous small equipment). We have provided a list of potential mitigation measures that primarily target emissions from drilling and compression engines and separator heaters, and would like discuss the feasibility of implementing these measures with the BLM and the Operator. We recommend that any mitigation measures implemented to avoid signi?cant impacts are implemented at Conditions of Approval (COAs) through this EA and in subsequent applications for permits to drill (APDS). Finally, we have questions regarding the emission inventory assumptions that we would like to discuss with the BLM and the operator. (1) Reduction Options for Drilling and Completion Engines: These engines constitute the majority of the project emissions, therefore, our recommendations focus on these sources. Currently, the MDP proposes to use Tier II engines for drilling and completion operations. These engines would emit an estimated 522.7 TPY of NOX in the maximum drilling years. We would like to discuss the feasibility of the following options for reducing emissions with the BLM and the operator: 0 Use of all Tier 4 compliant engines: It is important to clarify that we are speci?cally requesting the BLM and operator consider the feasibility of using Tier 4 compliant generator sets for all drilling and completion operations, this would require the use of generator sets in conjunction with electric motors to power equipment, rather than mechanical engines/rigs]. If this option were implemented, engines would meet the 0.5 NOx/hp~hr and would reduce drilling and completion emissions by roughly 90%. This option was deemed feasible by the four corners air quality task force. We recognize that fleet turnover would likely need to occur to fully implement these types of engines; however, due to the large reduction in emissions, we recommend that this Option be considered. 0 Retro?t of Tier 2 engines with Selective Catalytic Reduction (SCR): We note that the addition of SCR systems to generator sets has been successfully demonstrated in the Jonah-Pinedale ?eld in Wyoming, achieving 80% to 7 Mechanical engines have a NO): emission factor of 2.6 g/hp?hr. 6 upwards ef QD?i?a reductions in HOE emissiens frem these enginess. Hills reductien requirements were implemented in respense te eencems regarding visibility impairment in the nearby Wind River Wilderness, a Class 1 area managed by the USPS. Ups-raters and central system manufacturers have been able te everceme difficulties asseeiated with installing SCR an engines used fer drilling eperatiens, including ?uctuating leads and exhaust temperatures, extreme swings in weather eenditiens and pertability. This eptien was deemed feasible by the fear centers air quality task farce and we recen'tmend that this teehnelegy be eensidered as part ef a Nils reducticn strategy. I Use gas??red er deaf??rei engine's: Beth natural gas-fired and dualv fuel engines have preven te be feasible. eest effective eptiens fer drilling eperatiens in varieus basins threugheut the United States and Canada.? We nete that publicly available data shaws that EQT. Apache Carperatien. Chesapeake Energy, Stateil, Eneana Cerperatien, Cabet Oil and Gas, r?tntere Resources, Energy and Seneca Reseurees have all successfully empleyed natural gas-fired er dual?fuel engines fer drilling aperatierts. Lique?ed Natural Gas (LNG) and dual-fuel engines have alse been successfully empleyed in eempletien {hydraulic fracturing} eperatiens.H '2 This is must clearly highlighted by Chesapeake Energ ?s meve in 20] i te transitien all efits hydraulic fracturing equipment to LNG. The use of natural gas-?red and dual- fuel engines can achieve upwards ef an 35% reductien in N01: emissiens {relative ?in Tier 1 engines) .14 We recognize that H?fm'?f gets-fired and duel??re! engines may net be suitable fer all eperatienal circumstances; hewever, given that they have been successfully implemented by ntuncreus eperaters in a variety ef areas and eperatiens, we strongly that their use be censiderecl. I Electrifieetien efrt't'iifing This eptiett weuld virtually eliminate ?Git emissions from the drilling phase and has been used successfully in the a See intenneunlain Oil and Gas BMP Prejeet, available at: the Fear Cemers Air Quality Task Ferce Repert ef Mitigatien Gptiens fer the Gil and Gas Industry. available at: Decaf-1C AGTF Rc pert FINAL Giland? aspdt'. 9 David HillT ?Eneana Initiative Undersceres Envirenmenlal. Eeenemie Bene?ts Peivering Rigs Dn Natural Gas.? The American 01'! if: Gas Reperter, Aug. 20] l. in Charlie Riedl. IrIl's'atural Gas Gaining Greund As Fuel.? The Gt! Gas Reperter. Get. 20 i d, 1' '1 David G. Gallagher1 ?Bl?teling IEtig Step In Fracturing Future.? The American Oil all Gas Reperter, July. 2(113. future. '1 Kulkami, P. Gas?Driven Hydraulic Fracturing and Drilling Cut Casts. Reduce Envirenmenlal Impact. Gulf Publising Cempany. resI'ZU Ett'i'fgasdrivc Chesapeake Energy. (EDI Chesapeake energy eerperatien unveils beld plan te transferm LLB. transpertatien fuels market and reduce ail imparts [Press release]. Retrieved frem mall)?- See l-?eur Centers Air Quality Task Force Rupert ef Mitigatien Gptiens fer the Gil and Gas Industry, available at: DilandGas.ndf. 1 Marcellus shale by CONSOL Energy. '5 We recommend that electri?cation of drilling operations be considered for the Hayhurst project given that electric power may be available in the MDP area. 0 Phased drilling approach: One remaining option is to limit the number of drilling and/or fracturing operations that can occur simultaneously to a level that eliminates the signi?cant adverse effects of nitrogen deposition, as demonstrated through modeling. (2) Reduction Options for ompressors: As proposed, the compressors are well controlled at 0.5 for the small compressors (1,380 bhp/unit) and 0.3 g/bhp-hr for the large compressors (5,000 bhp/unit). As such, we believe the only remaining option to reduce emissions from the compressors would be to electrify the compression. Based on the EA, the operator is already proposing to build a substation to power gas lift pump systems and chemical injectors. We request that BLM consider whether electri?cation of the compressors is feasible for this MDP area. (3 N0x Reduction Options for Separator Heaters: In addition, we recommend that using the minimum temperature necessary and insulating separator heaters (heater treaters) can minimize emissions through reduced fuel usage for this equipment. We recognize that quanti?cation of emission reduction from this recommendation is dif?cult; however, this recommendation would be relatively easy to implement and likely cost neutral as a result of reduced fuel usage. (4) Additional Mitigation Measures: As noted, we would like the BLM and the operator to address these recommendations and speci?cally, their feasibility for operations in the MDP area. We welcome input regarding any additional options for NO): emission reductions (or combination thereof) that may achieve the same level of control necessary to reduce the signi?cant adverse effects. (5) Conditions of Approval: We believe any emission reductions identi?ed and agreed to would need to be implemented through COAs in the ?nal EA and subsequent APDS. If a ?mitigated? ?nding of no signi?cant impact (FONSI) is the ?nal decision document, the COAs should also be referenced in and incorporated into the FONSI associated with the MDP to ensure they are carried into subsequent APDs. (6) Emission Inventory Assumptions: We have several questions regarding the emission inventory assumptions for fuel usage for drilling operations, and whether completion ?aring should be included in the inventory. These assumptions impact the estimated emissions from drilling rigs and completion operations. We note that while this is important for determining the level of impact, we do not anticipate that the answer to this question will affect the mix of sources we should focus on to achieve reductions. ?5 Timothy Puko. ?Consoi Energy to reduce air pollution of airport drilling with electric engines,? Pittsburgh Tribune?Review, Dec. 2013, 8 The emissions inventory assumes that Drill Rigs operate 355 hours per well (or roughly 15 days assuming 24-hr operation) and that completion rigs will operate 261 hours per well (or roughly 11 days assuming 24-hr operation). However, page 2-15 of the EA states: well is expected to require 24 to 60 days to drill and an additional 34 to 47 days to complete.? We request two points of clari?cation regarding these assumptions: (1) The operating hours assumed in the inventory are calculated based on the fuel consumption for each engine type (gal/well). The footnotes in the inventory state that the gal/well estimates are based on ?historical fuel consumption records provided by Chevron.? Are the historical fuel consumption records speci?c to this area not part of a national or regional average) and for similar well types unconventional multi-lateral wells rather than conventional wells)? Please provide the additional information that was used to develop the fuel consumption estimates. (2) Recognizing that there will be some downtime during drilling, please explain the large discrepancy between the estimates disclosed on page 2-15 of the BA for drilling and completion time and those assumed in the emissions inventory. 0 The emissions inventory does not include any emissions associated with completions ?aring. Please clarify whether ?are devices will be used for any period of time during completion operations, or whether gas produced during completions will be routed to a gas gathering system. Other A UK VI tripacts If additional reductions were to be obtained, we believe that these could address other regional AQRV concerns, such as visibility impairment and increased ozone levels (recognizing that CALPUFF does not simulate ozone). In our recent review of the administrative DEIS for the Carlsbad F0 (CFO) RMP, we noted that we have signi?cant concerns regarding the predicted cumulative ozone, nitrogen deposition and potential visibility impacts in Carlsbad Caverns NP. We have raised these concerns, and the need for associated mitigation, in previous communications including comments on the CFO RMP air quality technical support document (2013 through 2014). Additional reductions from this project will also address ongoing concerns regarding other adverse effects to AQRVs from cumulative oil and gas development. We would like to note that very little information regarding the visibility analysis methods for the Hayhurst project is provided in the EA. Additional time is necessary for the NPS to review the visibility modeling analysis, and note that generally, it is preferable to work through these steps well before the EA is released for public comment (see MOU comments below). As stated in our comments on the RMP, the FLMs do not agree with the visibility analysis methods utilized in the RMP assessment.?5 It is unclear at this time whether similar deviations from FLM '6 It appears the reported visibility results in table 4.2-1 [5 of the RMP ADEIS were arbitrarily reduced, and do not re?ect the actual magnitude of modeled visibility impacts according to FLM recommended analysis procedures. Page 4-236 states: "The absolute total number ofdays of signi?cant visibility changes (greater than 0.5 delta-dv and greater than l.0 delta-dv) calculated 9 recommend methods were used in the MDF analysis. As such, we cannot conclusively comment on the predicted visibility impacts from MOP-related activities. Air Quality; MDU As noted above, this project falls under the scope of the MOD among the LLB. Department of Agriculture, LLB. Department of the Interior and the LLB. Environmental Protection Agency Regarding Air Quality Analyses and Mitigation for Federal Gil and Gas Decisions Througlt the National Environmental Policy Act Process. We appreciate that BLM is now reaching out to the NPS regarding this project, and working to resolve NPS concerns. We believe that Blel?s recent efforts are consistent with the goals of the MGU. However. for future projects that may impact Carlsbad Caverns [or any other NPS unit}, we recommend that a technical workgroup is convened and the MGU procedures are implemented ?early in the planning process," pre- scoping or well before the public comment period as speci?ed in the MGU. The MGM establishes a collaborative process for analysing and mitigating impacts to air resources for federal oil and gas planning, leasing and development. implemented, we holieve the process can facilitate the resolution of many issues in advance of the public comment period. Night Sky Intgnets We greatly appreciate Blel's inclusion of dark night skies in the affected environment, section 3.14, as well as the discussion ofcumulative impacts and proposed mitigation measures. Given the number of proposed wells {up to 436 wells on It]? well pads) and the existing impacts from oil and gas development in the area of in?uence, we are concerned about cumulative impacts to night skies. Publicly available data show that sky glow in the area is growing. and more effective BMPs with mitigation of gas ?aring may be needed. The image below from the New World Atlgs of Artificial Sky Brightness shows extensive existing sky glow impacts from nearby oil and gas development extending across Carlsbad Caverns National Park and into Guadalupe Mountains National Park. The light sources from oil and gas development are very substantialm; light from this development essentially dwarfs light from the town ofCarlsbad [See Figure in Attachment 1 the large orange area northeast of Carlsbad Caverns National Park). tor base year seas, base case 2m and future altem olives is 366 days [every day leap year}. to show relative impacts among the alternatives with respect to the base case emissions scenarios, the calculated delta-(iv {change in visibility] was divided by 15 For each day before counting and reporting the number of days above the thresholds. This essentially equates to evaluating impacts for thresholds of 15 chIa-dv and ii delta-dv." '1 At} MDU Section preparing an Environmental Assessment for a Federal oil and gas decision where air quality or are issues wamtnting Hlii'A analysis. the Lead Agency will consider following the procedures established in this MDU and the Appendix." in Section the MDU list criteria for determining when air quality or AQRVs may be affected {and thus modeling should be implemented}. [line of these criteria is "proximity? to it Class I or sensitive Gloss ll area. For more infonnalien on oil and gas impacts to night shins in the Fennian Basin see Upgraded Rig Lighting Improves blight Time 1 itisibility While Reducing Stray Light and the Threat In Dark Skies in West Texas. 1015. Summary at: ittlno?t?u ghtin ens-ni it] While ideally it is true that in the absence of existing impacts, "implementation of BMPs for light ?xtures would minimize the potential for sky glow and glare," as stated in the Cumulative Impacts section, this may he questioned in areas where sky glow and glare are already extensive. impacts on the bat population of Carlsbad Caverns National Park should be addressed. There is growing evidence of arti?cial light impacts on wildlife, as documented in a new RPS publication: ?Artificial night lighting and protected lands: Ecological effects and management approaches" We would appreciate addition of this reference to the EA. See also: Stone, E. L., S. Harris, and G. Jones. 2015. Impacts ofarti?cial lighting on bats: a review of challenges and solutions. Mammalian Etiology- ?ir Sangetiertrunde 8th? 3419. "Therefore, we are concerned that more substantial BMPs may be necessary for both existing and future operations to minimise cumulative impacts that are already substantial. We respect?slly recommend that full cutoff shielding is incorporated in the list oflighting mitigation measures, as follows: I Chevron will use minimal tight necessary for site safety, security, and operations. I Light will be directed downward or only where needed. I l.oW?pressure sodium lamps, such as yellow LED lighting or equivalent, will be used to reduce sky glow and wildlife impacts. I Properly shielded {full cutoff preferred) and mounted light ?xtures would be used to reduce sky glow front upward pointing light, as well as trespass from light falling outside of desired area ofillumination. The need for more effective Bl'les also applies to gas ?aring. When tlterc are hundreds of wells, even a few exposed gas flares can produce signi?cant impacts for miles. Letters by private citizens indicate that looking to the east from Carlsbad Caverns National Park, 25 or more exposed gas flares can now be seen lighting up the sky on any given night. As noted above, it is unclear whether completions flaring will be implemented. lfflaring will be utilised in the area, we strongly recommend the following BMP for new and existing operations: I Produced or recycled gas will not he llared at night except for instances where ?aring is necessary to protect operating personnel or to ensure the safe operation of surface facilities. Options to avoid nighttime flaring of gas may include storage. In those instances when nighttime flaring of gas is required, a visual screen or enclosed combustion chamber [?combustor") will he used to prevent adverse impacts on nearby national parks. In closing, thank you for reaching out to the NPS regarding the proposed project and the predicted deposition impacts in Carlsbad Caverns NF. We believe the opportunity to discuss and ultimately implement N?x and night sky mitigation options is invaluable to protecting resources at Carlsbad Caverns NP, a park that has been identi?ed as having numerous outstanding world-class resources through its international recognition. As stated previously, we do not believe the air resource impacts from the proposed project are congruent with the issuance ofa We also have significant concerns regarding the cumulative impacts to night skies. We look forward to ?nding mutually,' agreeable solutions to resolve these issues, and recognize that such solutions should address the planning needs as well as the NPS concerns regarding signi?cant adverse effects. It'you have any questions regarding these comments, please contact Andrea Stacy with the NPS Air Resources Division at 303-969-2316 or Randy Stanleyr with the interrnountain region's night sky program at or Rodney,I Horrockc with Carlsbad Caverns HP at Sincerely, Doug Neighbor, Superintendent, Carlsbad Caverns National Park Cc: Collin Campbell, Deputy Regional Director, Chief of Clperations, Interrnountain Region, National Park Service A (to clone-nits: Maps and Figures 2. Citations l2 Attachment 1: "Irlaps In)? - - 5 5:5:me {imperial Lani - urn-ml - ll?sdu?llna?l] - Bambi-Md 11.0 - MI I .. - '3".aniu Purl: having I'cgclalinll types Ella r?ctcrind by of plant cummunilici to he must scnsilivc In dlpu?liun. h?i-Ell an nulricnt critical load vnlucs compiled by Allen and Gciscr Ni?m Arti?cial 3d a 1. Elm b1 Lemnd khaki-v?? ?3 0 Map 1: Sky glow impact-5 frum nearby nil and 2M Park and inm Guadalupe Munnlnins Park. Attachment 2 Citations Allen. E. 13.. L. E. Rae. R. J. Steers, A. thnerowitca. and M. E. Fenn. E??ii. Impacts of atmospheric nitrogen deposition on vegetation and soils in Joshua Tree National Paris. Pages in R. H. Welsh. L. F. I-?cnstermaker. J. S. l-Ieaton. D. L. Hoghson. E. McDonald, and D. M. Miller. editors. The Mojave Desert: Ecosystem Processes and Sustainability. UniversityI of Nevada Press. Las Vegas. Brooks. M. L. Competition between alien annual grasses and native annual plants in the Mojave Desert. American Midland Naturalist Brooks. M. L. REDS. Effects of increased soil nitrogen on the dominance of alien annual plants in the Mojave Desert. Jonmal of Applied Ecolog}.r moss-353. Lyons. K. (3., B. G. Maldonado-Lea]. and Gwen. 20H. Commonity and Ecosystem Effects of Buffelgrass (Pennisetum ciliate] and Nitrogen Deposition in the Sonoran Desert. invasive Plant Science and Management ti:tiS-T3. Marshall, v. M. M. M. Lewis. and B. Ustendorf. EDIE. Buffel grass tCenchrus ciliaris) as an invader and threat to in arid environments: A review. Journal of Arid Environments 73:142. Pardo. L. H.. M. E. Fenn, C. L. Goodale. L. H. Geiser. C. T. Driscoll, E. E. Allen. J. S. Baron. It. Bobbittk. W. D. Bowtnan, C. M. Clark. B. Emmett. F. S. Gilliam. T. L. Grca?ver. S. J. Hall. E. A. Lillesltov, L. Lin. J. A. K. J. Nadelhofi'er. S. S. Feral-tie, M. J. Robin- Abbott. J. L. Stoddard. K. C. and R. L. Dennis. It'll 1. Effects of nitrogen deposition and empirical nitrogen critical loads for ecoregions ofthe United States. Ecological Applications Rae. L.. R. Steers. and E. Allen. 2011. Effects of natural and anthropogenic gradients on native and exotic winter annuals in a southern California Desert. Plant Ecology Rae. L. E.. E. E. Allen. and T. Meisner. Risk-based determination of critical nitrogen deposition loads for ?re spread in southern California deserts. Ecological Applications 2?1132?-1335. Root, li.T.. L.l-i. Geiser, M.E. Penn. 3. Jovan. MA. i-luttcn. S. Altuja. K. Dillrnan. D.Schirokauer. 5. lJt. McMurray. E?ll A simple tool for estimating Iltroughfail nitrogen deposition in forests of western North America using lichens. Forest Ecology.r and Management ass: