Document ID: EPA-R09-OAR-2019-0528-0003
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2019-11-04T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            REGION IX AIR DIVISION

                          Technical Support Document
                                      for
                              EPA's Rulemaking
                                    for the
                     California State Implementation Plan
                                       
               Northern Sierra Air Quality Management District 
                                       
                Reasonably Available Control Technology (RACT)
                   State Implementation Plan (SIP) Revision
                                      for
                             Western Nevada County
                        8-Hour Ozone Nonattainment Area

                              
                           Prepared by: Stanley Tong

                                September 2019

RULE IDENTIFICATION 
Agency
Northern Sierra Air Quality Management District (NSAQMD or "District") 
SIP Approved Version
There is no previous SIP-approved NSAQMD RACT SIP for the 2008 8-hour ozone national ambient air quality standard (NAAQS) for Western Nevada County, but we previously approved the following document for the 1997 8-hour ozone NAAQS: 

"Reasonably Available Control Technology (RACT) State Implementation Plan (SIP) for Western Nevada County 8-Hour Ozone Non-Attainment Area" ("2007 RACT SIP"), adopted June 25, 2007.
  Submitted - February 7, 2008.
  EPA Approved  -  April 13, 2015 (80 FR 19544).

Subject of this Technical Support Document
"Reasonably Available Control Technology (RACT) State Implementation Plan (SIP) Revision for Western Nevada County 8-Hour Ozone Nonattainment Area" ("2018 RACT SIP"), adopted March 26, 2018.
  Submitted  -  June 7, 2018.

Completeness Finding
Determination of Completeness letter: November 29, 2018.

1. BACKGROUND  -  

This technical support document (TSD) relates to the Clean Air Act (CAA or the ACT) requirement for certain sources of air pollution to implement controls that are determined to be reasonable, also called Reasonably Available Control Technology or RACT. These requirements are found in title I, part D, subpart 2 of the Act and the U.S. Environmental Protection Agency's (EPA) implementing regulations addressing the State Implementation Plan (SIP) requirements for RACT for the 2008 ozone NAAQS at title 40 of the Code of Federal Regulations (CFR) part 51, subpart Aa, section 51.1112. This TSD will focus on the EPA's evaluation of whether the "Reasonably Available Control Technology (RACT) State Implementation Plan (SIP) Revision for Western Nevada County 8-Hour Ozone Nonattainment Area" adopted by the NSAQMD on March 26, 2018 and submitted to the EPA by the California Air Resources Board on June 7, 2018 ("2018 RACT SIP") meets CAA Section 182 RACT requirements.

CAA Section 182 requires that, for areas that are designated nonattainment for the ozone NAAQS and classified as a Moderate Area or above, States adopt RACT. CAA Section 182 specifies that RACT is required for volatile organic compound (VOC) sources covered by a control techniques guidelines (CTG) document and for all major stationary sources of VOC or oxides of nitrogen (NOx). States are required to submit a SIP revision providing for the implementation of RACT in such areas to the EPA for approval into their SIPs. 
	
Section III.D of the preamble to the EPA's final rule to implement the 2008 8-hour ozone NAAQS (80 FR 12264, March 6, 2015) discusses RACT requirements. It states in part that RACT SIPs must contain adopted RACT regulations, certifications where appropriate that existing provisions are RACT, and/or negative declarations that no sources in the nonattainment area are covered by a specific CTG. Id. at 12278. It also provides that states must submit appropriate supporting information for their RACT submissions as described in the EPA's implementation rule for the 1997 ozone NAAQS. See id. and 70 FR 71612, 71652 (November 29, 2005). 

The NSAQMD encompasses the California counties of Plumas, Sierra and Nevada. Western Nevada County (population approximately 78,000) is predominantly rural, with two small cities (Grass Valley and Nevada City). In 2012, Western Nevada County was initially classified as Marginal nonattainment for the 2008 8-hour ozone NAAQS. In 2016, Western Nevada County was reclassified to Moderate ozone nonattainment for the 2008 8-hour ozone NAAQS. In 2019, Western Nevada County was reclassified again, to Serious nonattainment, for the 2008 ozone NAAQS, effective September 23, 2019. As a result of the area's reclassification to Moderate, then Serious, nonattainment for the 2008 ozone NAAQS, stationary sources in the Western Nevada County ozone nonattainment area are subject to RACT, and the District was required to submit a SIP revision to address RACT requirements for the 2008 ozone NAAQS. 

The 2018 RACT SIP, including its negative declarations, provide NSAQMD's analysis of its compliance with CAA section 182 RACT requirements for the 2008 8-hour ozone NAAQS. At the time of the NSAQMD's adoption of the 2018 RACT SIP and its subsequent submittal by CARB to the EPA, the Western Nevada County ozone nonattainment area was classified as Moderate for the 2008 ozone NAAQS. However, in anticipation of the area's being bumped up to a Serious nonattainment classification, the NSAQMD's 2018 RACT SIP evaluated whether the District had any major VOC/NOx sources emitting at least 50 tons per year (tpy), which is the major source threshold for ozone precursors for Serious ozone nonattainment areas. The NSAQMD's 2018 RACT SIP noted that "[t]he largest stationary source of ozone precursors in the Western Nevada County ozone nonattainment area is currently a gas station that emits under 2 tons of precursors per year."
Shortly after the submittal to the EPA of the 2018 RACT SIP, on October 22, 2018, NSAQMD adopted the "Ozone Attainment Plan, Western Nevada County, State Implementation Plan for the 2008 Primary Federal 8-Hour Ozone Standard of .075 ppm" ("2018 Ozone Attainment Plan"). This SIP revision was submitted to the EPA by CARB on December 2, 2018 for approval into the California SIP. The 2018 Ozone Attainment Plan stated that the NSAQMD was requesting to bump up to a Serious nonattainment classification for the 2008 8-hour ozone NAAQS, and that it had structured the SIP revision to meet the CAA's Serious level requirements. 2018 Ozone Attainment Plan at 6, 9, 20.
The 2018 Ozone Attainment Plan noted that CAA sections 172(c)(1) and (c)(2) require the District to demonstrate that it has adopted all reasonably available control measures necessary to attain the 2008 8-hour Ozone NAAQS as expeditiously as practicable ("RACM"). Id. at 42. It stated that the District's stationary source NOx and VOC prohibitory rules had been addressed in the District's RACT SIP, noting that RACT is the minimum required level of RACM and applies to specific categories of stationary sources to which CTGs apply. Id. It also noted that the 2018 RACT SIP implements all applicable CTGs published by EPA through 2016. Id.

Because Western Nevada County is now classified as Serious nonattainment for the 2008 8-hour ozone NAAQS, and because NSAQMD's 2018 RACT SIP provided an analysis of RACT that addresses the requirements for a Serious area as well as a Moderate area in anticipation of this bump-up, we evaluated the 2018 RACT SIP submittal to determine whether it met RACT requirements for a Serious ozone nonattainment area as well those for a Moderate ozone nonattainment area.  Specifically, we evaluated NSAQMD's 2018 RACT SIP using the 50 tpy threshold for major stationary sources in Serious ozone nonattainment areas, including conducting a query of CARB's emissions inventory web site for stationary sources in Nevada County to determine if the District had any stationary sources emitting at least 50 tpy of VOC or NOx. 

2. SUBMITTAL SUMMARY  -  

As noted above, the District adopted its RACT SIP demonstration for the 2008 8-hour ozone NAAQS on March 26, 2018, and CARB submitted it to the EPA on June 7, 2018. The submittal acknowledged that the Western Nevada County ozone nonattainment area had an ozone nonattainment classification for the 2008 8-hour ozone NAAQS of Moderate, effective June 2016, and noted that the area would soon bump up again to a Serious ozone nonattainment classification. The submittal also stated that "...there are no major sources (that emit or have the potential to emit 50 tons or more per year) of ozone precursors located in the nonattainment area." The 50 tpy of VOC or NOx major source threshold cutoff used by NSAQMD corresponds to the threshold for a Serious ozone nonattainment area. CAA section 182(b)(2), (f) and 302(j).

The NSAQMD's 2018 RACT SIP analysis included the following elements:
 A short description of the counties and populations under the District's jurisdiction.
 A discussion of CAA RACT requirements, a summary of the District's efforts to demonstrate its stationary sources implemented RACT for the 1997 ozone NAAQS, and the steps taken to demonstrate RACT continues to be implemented for the 2008 8-hour ozone NAAQS.
 An applicability review of selected CTG documents where the District may have sources subject to the CTGs.
 Review of rules previously determined to meet current RACT requirements.
 Negative declaration determinations for the remainder of the CTGs.

3. EVALUATION CRITERIA  -  

The EPA evaluated the following elements of NSAQMD's 2018 RACT SIP: 
 RACT applicability determination for selected CTGs. 
 Determination concerning whether rules previously determined to meet RACT for the 1997 8-hour ozone NAAQS meet current RACT for the 2008 8-hour ozone NAAQS. 
 Negative declarations for all other CTGs and major VOC and NOx stationary sources.

The following documents were used to support our review of the 2018 RACT SIP and adopted rules: 

  :: "Final Rule to Implement the 8-Hour Ozone National Ambient Air Quality Standard  -  Phase 2" (70 FR 71612; November 29, 2005). 
  :: "Implementation of the 2008 National Ambient Air Quality Standards for Ozone: State Implementation Plan Requirements'' (80 FR 12264; March 6, 2015). 
  :: "State Implementation Plans, General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990" (57 FR 13498; April 16, 1992). 
  :: "State Implementation Plans; Nitrogen Oxides Supplement to the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990" (57 FR 55620, November 25, 1992) ("the NOx Supplement"). 
  :: 	Memorandum dated May 18, 2006, from William T. Harnett, Director, Air Quality Policy Division, to Regional Air Division Directors, Subject: "RACT Qs & As  -  Reasonably Available Control Technology (RACT): Questions and Answers." 
  :: 	EPA's CTGs and Alternative Control Techniques (ACTs): https://www.epa.gov/ozone-pollution/control-techniques-guidelines-and-alternative-control-techniques-documents-reducing  
  :: 	NSAQMD, CARB, and EPA Region IX databases of NSAQMD rules 
   	NSAQMD: http://myairdistrict.com/index.php/rules/ 
   	CARB: https://ww3.arb.ca.gov/drdb/nsi/cur.htm  
   	EPA: https://www.epa.gov/sips-ca/epa-approved-northern-sierra-air-district-regulations-california-sip

3.1 RACT applicability determination for selected CTGs. 

NSAQMD's 2018 RACT SIP states that for the 2008 ozone standard, it reviewed its permit files, performed an internet search, and consulted with knowledgeable District personnel and concluded that the negative declarations it adopted for the 1997 ozone NAAQS continue to be valid and applicable. This analysis is discussed below in Section 3.4.

The District also concluded that negative declarations should also be adopted for the following CTGs because either there were no sources in the Western Nevada County ozone nonattainment area subject to these CTG categories or all of the sources were below the CTGs' applicability thresholds.
	EPA 453/B16-001 Oil and Natural Gas Industry
	EPA-450/2-77-035 Bulk Gasoline Plants
	EPA-450/2-77-036 Storage of Petroleum Liquids in Fixed-Roof Tanks

Below are excerpts from NSAQMD's 2018 RACT SIP that discuss the District's review of whether it has stationary sources subject to these CTGs, and the EPA's evaluation of NSAQMD's submittal.
	
3.1.1 EPA 453/B16-001 Oil and Natural Gas Industry

NSAQMD's 2018 RACT SIP states that "[t]here are no oil or natural gas production or processing facilities in the western Nevada County ozone nonattainment area. There also are no pre-distribution processes involving storage tanks or vessels in the area. All oil and natural gas industry activity in the nonattainment area is part of the distribution process." The District further states that all of the nonattainment area's piped natural gas is supplied by the Pacific Gas and Electric Company (PG&E) and that there are no natural gas processing plants, well sites, oil wells, pipelines, and no place where rail tank cars are loaded or unloaded, and no ports in the ozone nonattainment area.

The District further clarified that all of the natural gas is part of the distribution process and verified this information through emails with PG&E.

3.1.1.1 The EPA's evaluation

On September 21, 2018, CARB released its staff report for the proposed submission of California's state-wide greenhouse gas emission standards for crude oil and natural gas facilities ("CARB Staff Report"). The CARB Staff Report provides a comparison of the State-wide rule to the EPA's 2016 CTG for the Oil and Natural Gas Industry. The CARB Staff Report states that of the air districts with nonattainment areas, only six have oil and gas operations subject to the EPA's CTG. Northern Sierra AQMD is not one of the six air districts listed by CARB as having sources covered by the 2016 Oil and Gas CTG. 

We also reviewed California's Department of Oil and Gas Well Finder, CARB's pollution mapping tool, and California Natural Gas Pipelines internet sites and did not find indications of oil or gas wells in Nevada County. We therefore agree that there do not appear to be any sources subject to the EPA's 2016 Oil and Natural Gas Industry CTG in the Western Nevada County ozone nonattainment area.

3.1.2 EPA-450/2-77-035 Bulk Gasoline Plants

NSAQMD's 2018 RACT SIP states:

   The CTG (Control of Volatile Organic Emissions from Bulk Gasoline Plants, EPA-450/2-77-035, December 1977) was addressed in the negative declaration submitted to EPA on 2/7/08, by stating that rules 219 and 220 were determined by CARB to meet RACT, but the negative declaration appears to never have been either approved or disapproved by EPA. This is probably because rules 219 and 220 are not in the SIP. Nonetheless, the NSAQMD reviewed its records and learned that the throughput reported by the only source of this type in the nonattainment area is below the CTG's applicability cutoff of 4,000 gallons per day.[] Thus, the CTG does not apply and the NSAQMD is proposing to adopt a negative declaration.

3.1.2.1 The EPA's evaluation

We reviewed our historical files and conducted an internet search for bulk gasoline fueling plants in the Western Nevada County ozone nonattainment area and identified the following three potential bulk gasoline plants. 

	Hunt and Sons Inc  -  720 S. Auburn St., Grass Valley, CA 95945
	Hunt and Sons Inc  -  335 Railroad Ave., Grass Valley, CA 95945
	Robinson Bulk Fuels & Oil  -  133 Lower Grass Valley Road, Nevada City 95959

Based on information provided by the NSAQMD, the facility at 335 Railroad Ave. was torn down and has not been rebuilt. Data previously provided by one of the bulk gasoline plants to the NSAQMD indicated that 2012, 2013, and 2014 throughput was well below the applicable CTG's 4,000 gallons per day (gpd) exemption threshold for each of the years. We requested updated throughput data for the two remaining bulk gasoline plants, and determined, based on data from 2015 - 2017 at one plant, and data from 2016 - 2018 at the other plant, that both bulk gasoline plants continue to be well below the CTG's applicability threshold. We therefore agree with NSAQMD's negative declaration for the bulk gasoline plant CTG.
 
With regards to Rules 219 and 220, the EPA searched its files and reviewed CARB's rules log database and agree that these rules are not in the SIP. We believe these two rules have not been submitted for SIP approval based on CARB's February 7, 2008 submittal of NSAQMD's RACT SIP for the 1997 8-hour ozone NAAQS, which states "...The supplemental documentation includes rules to implement RACT but are included as background information only. The rules will be formally submitted for incorporation into the SIP under separate cover." However, Rules 219 and 220 are not a required RACT submittal because NSAQMD has provided data showing it has no bulk gasoline plants exceeding the CTG's 4,000-gallon applicability threshold. 

3.1.3 EPA-450/2-77-036 Storage of Petroleum Liquids in Fixed-Roof Tanks

NSAQMD's 2018 RACT SIP states:

    In preparation for this submittal, the NSAQMD reviewed EPA-450/2077-036 [sic] Control of Volatile Organic Emissions from Storage of Petroleum Liquids in Fixed-Roof Tanks, December 1977 [] stationary source permits and records for non-permitted sources that have any relation to the petroleum product market and determined that there are no fixed roof petroleum liquid (having a true vapor pressure> 10.5 kPa) storage tanks exceeding 40,000 gallons [ . . .] [T]he CTG applicability cut-off volume is 150,000 liters, which equals 39,625.8 gallons, so 40,000 gallons is the volume commonly used in rulemaking and applicability analyses. The NSAQMD believes it is aware of all petroleum handling facilities in its jurisdiction. Thus, the CTG does not apply and the NSAQMD is proposing to adopt a negative declaration.

3.1.3.1 The EPA's evaluation

The CTG entitled "Control of Volatile Organic Emissions from Storage of Petroleum Liquids in Fixed-Roof Tanks" (EPA-450/2-77-036) applies to fixed roof storage tanks with capacities greater than 150,000 liters (approximately 39,626 gallons) with a true vapor pressure greater than 10.5 kilopascal (approximately 1.5 pounds per square inch (psi)). Underground tanks at retail gasoline stations generally range from 4,000 to 20,000 gallon capacities, which are below the 40,000-gallon applicability threshold for this CTG.

The District confirmed in a 2019 email to the EPA that neither of the operating bulk gasoline plants listed in section 3.1.2 above has petroleum storage tanks with a 40,000 gallon or greater capacity, and that the largest tanks these facilities have are 12,000-gallon capacity. We also reviewed CARB's emissions inventory database for facilities that may use petroleum storage tanks equal to or greater than 40,000 gallons and did not find any facilities. We therefore agree that NSAQMD's negative declaration for this CTG is appropriate. 

3.2 NSAQMD Review of Previously Adopted RACT Rules 

3.2.1 Rule 214, "Phase 1 Vapor Recovery" 

NSAQMD's 2018 RACT SIP states that Rule 214:

was amended on 4/25/2011 and approved into the SIP on 1/7/2013 (78 FR 898) as meeting RACT, and the District is not aware of other reasonably available technology capable of reducing emissions from this source category. Based on the NSAQMD's research, the requirements are comparable to most other nonattainment areas, differing mainly in details rather than key limits and exemptions. For example, Placer County, as part of the Sacramento Severe Nonattainment Area, has a similar rule (Rule 213, amended 2/21/13) but does not include the pump-out of storage tanks into mobile fuelers - only transfer into storage tanks. Ventura County APCD's similar Phase 1 rule (Rule 70, amended April 2009) also does not apply to gasoline transfer into mobile fuelers, whereas NSAQMD's rule does. 

3.2.1.1 The EPA's evaluation

As stated in NSAQMD's 2018 RACT SIP, the EPA approved Rule 214, "Phase I Vapor Recovery Requirements," into the SIP on 1/7/2013 (78 FR 898), finding that the rule met the applicable CTG as well as meeting RACT. The CTG that applies to this source category is entitled "Design Criteria for Stage I Vapor Control Systems  -  Gasoline Service Stations" (EPA-450/R-75-102).

The EPA's Issues Relating to VOC Regulation Cutpoints, Deficiencies, and Deviations (also known as "The Bluebook") indicates that the CTG exempts service stations with gasoline throughputs of less than 10,000 gallons per month (120,000 gallons per year). Based on communications with the California Energy Commission, there do not appear to be any retail automobile gasoline stations in the Western Nevada County ozone nonattainment area with throughputs of less than 10,000 gallons per month. Therefore, the CTG would apply to all retail automobile gas stations in the area. 

In determining that Rule 214 meets the CTG (i.e., EPA-450/R-75-102), we reviewed Rule 214 and compared its requirements to analogous rules, e.g., Sacramento Metropolitan AQMD Rule 448, "Gasoline Transfer into Stationary Storage Containers" (amended 2/26/09), Placer County APCD Rule 213, "Gasoline Transfer into Stationary Storage Containers" (amended 2/21/13), and South Coast AQMD Rule 461, "Gasoline Transfer and Dispensing" (amended 4/6/12). We conclude that Northern Sierra Rule 214 is generally consistent with analogous rules in these other air districts and continues to implement current RACT. 

NSAQMD's 2018 RACT SIP's Summary Table of All CTGs also lists Rule 214 as implementing the CTG entitled "Control of Volatile Organic Compound Leaks from Gasoline Tank Trucks and Vapor Collection Systems" (EPA-450/2-78-051). This CTG applies to gasoline tank trucks equipped with vapor recovery and requires that the gasoline tank trucks be vapor tight. Rule 214 Part 4.3.D, "Delivery Vessels", prohibits persons from operating gasoline delivery vessels unless the delivery vessels have been certified to CARB Certification Procedure CP-204 entitled "Certification Procedure for Vapor Recovery Systems of Cargo Tanks." CARB's certification procedure evaluates gasoline delivery vessels for vapor tightness. We agree that Rule 214 together with CARB's certification procedure implements this CTG. 

Recommendations
The following recommendations are provided to improve the RACT SIP; however, they are not approvability issues. For completeness, we are also including below recommendations we made previously in our action approving Rule 214:

1. Rule 214, section 4.2.B exempts gasoline service stations from the rule's requirements if throughput is less than 10,000 gallons per month for each month of the operation within a calendar year. We recommend Rule 214 be amended to require facilities using this exemption to maintain records of all gasoline delivered to the site for at least 5 years. 

2. Rule 214, Section 5.1 A., "Testing Procedures", should be updated to allow newer versions of test methods to be used (e.g., ASTM D2879-97 (2007) "Test Method for Vapor Pressure-Temperature Relationship and Initial Decomposition Temperature of Liquids by Isoteniscope," and ASTM D323-06 "Test Method for Vapor Pressure of Petroleum Products (Reid Method)," similar to Sacramento Metropolitan Air Quality Management District Rule 448 section 501.1.

3. The TSD for our 2013 approval of Rule 214 (amended 4/25/11) included the following recommendations for improvement the next time Rule 214 is amended: 

      Rule 214 Phase I Vapor Recovery Requirements:
:: To stay consistent with CARB's Certification Procedure for Vapor Recovery Systems at
Gasoline Dispensing Facilities (CP 201) section 3.1, we recommend the District revise
section 4.3C.ii and iii to increase the vapor recovery efficiency from 95% to 98%.
:: We recommend adopting the rule provisions currently applied to the federal ozone
nonattainment area for the attainment areas within the District as well. This would
further reduce emissions that may help the nonattainment area, and provide greater
fairness and consistency throughout the District and the State.
:: We recommend requiring sources to train at least one employee to be familiar with
Phase I equipment inspection and maintenance. See, for example, Antelope Valley
	AQMD Regulation 4, Rule 461, Section C(4)(a)(iv).

Technical Support Document for the EPA's Direct Final Rulemaking for the California State Implementation Plan- Northern Sierra Air Quality Management District, Rule 214, Phase I Vapor Recovery Requirements, July 2012, at 3, retrieved September 25, 2019, from https://www.regulations.gov/contentStreamer?documentId=EPA-R09-OAR-2012-0587-0016&contentType=pdf.

3.2.2 Rule 215, "Phase II Vapor Recovery System Requirements" 

NSAQMD's 2018 RACT SIP states that Rule 215:

was last amended 2/22/10 and approved into the SIP for the 1997 standard 7/26/11 (76 FR 44493). This 14-page rule contains many specific requirements and is difficult to compare with similar rules from other areas, which often combine requirements for Phase 1, Phase 2 and bulk gasoline facilities into a single rule. Using Ventura County APCD again for comparison, Ventura's similar rule (Rule 70, amended April 2009, which covers both Phase 1 and Phase 2 gasoline vapor recovery) was last amended earlier than NSAQMD's. They both require 95% control efficiency and defect-free, CARB-certified components. Ventura's rule exempts privately owned storage containers fueling a fleet with 95% ORVR equipped vehicles, whereas NSAQMD's rule only exempts non-retail facilities fueling a fleet with 100% ORVR-equipped vehicles, making NSAQMD's rule more stringent in this respect.

3.2.2.1 The EPA's evaluation

The EPA has not issued a CTG for refueling of motor vehicles, and, based on a review of CARB's emissions inventory for 2017, there are no gasoline stations that are major stationary sources in Western Nevada County. Therefore, Rule 215 is not currently required for the RACT SIP. Nonetheless, on July 26, 2011, at the request of the District, the EPA approved Rule 215 into the SIP, finding that it satisfied RACT requirements. The information provided in the 2018 RACT SIP shows that the rule also implements RACT for the 2008 8-hour ozone NAAQS.

Recommendations
The following recommendations are provided to improve the SIP and are not approvability issues. The TSD for our 2011 approval of Rule 215 (amended 2/22/10) included the following recommendations for the next time this rule is amended: 

      Rule 215 Phase II Vapor Recovery System Requirements 
      :: We recommend adopting the rule provisions currently applied to the federal ozone
nonattainment area for the attainment areas within the District as well.
:: We recommend requiring sources to train at least one employee to be familiar with
Phase II equipment inspection and maintenance. See, for example, Antelope Valley
	AQMD Regulation 4, Rule 461, Section C(4)(a)(iv).

Technical Support Document for EPA's Final Rulemaking for the California State Implementation Plan- Northern Sierra Air Quality Management District, Rule 215, Phase II Vapor Recovery System Requirements, November 12, 2010, at 3, retrieved September 25, 2019, from https://www.regulations.gov/contentStreamer?documentId=EPA-R09-OAR-2011-0042-0006&contentType=pdf.

3.2.3 Rule 227, "Cutback Asphalt" 

NSAQMD's 2018 RACT SIP states that Rule 227:

was approved into the SIP for the 1997 standard 10/30/09. The NSAQMD compared its rule with Ventura's Serious classification Cutback Asphalt rule (74.4, amended July 1983) and found that Ventura's [rule] is less stringent. Ventura's [rule] has an exemption for penetrating prime coat applications and doesn't include recordkeeping requirements. In addition, the rule that the NSAQMD modeled its rule after is still considered RACT for the Sacramento Severe Nonattainment Area. The District is not aware of other reasonably available technological or operational controls likely to significantly reduce emissions from this source category for the 2008 ozone standard.

3.2.3.1 The EPA's evaluation

The CTG entitled "Control of Volatile Organic Emissions from Use of Cutback Asphalt" (EPA-450/2-77-37) discusses the control of VOCs from paving asphalts that are liquified with petroleum distillate. The control technique discussed in the CTG involves the substitution of an emulsifying agent and water for the petroleum distillate to achieve VOC emission reductions.

The EPA's model VOC RACT rule defines cutback asphalt as an asphalt cement that has been liquefied by blending with petroleum solvents. The asphalt solidifies to form a hard surface when the solvents evaporate. Emulsified asphalt is an emulsion of asphalt cement and water that contains a small amount of emulsifying agent. The model rule generally prohibits the manufacture, mixing, storage, use or application of cutback asphalt during the ozone season except under certain conditions which include the approval of the Administrator. The model rule also prohibits the manufacturing, mixing, storage, or use of emulsified asphalt that contains any VOCs during the ozone season.

We reviewed the VOC emission limits in Rule 227 against the emission limits in analogous rules promulgated by other air districts such as Sacramento Metropolitan Rule AQMD Rule 453, "Cutback And Emulsified Asphalt Paving Material," (8/31/82), Placer County APCD Rule 217, "Cutback And Emulsified Asphalt Paving Materials" (10/19/93), and South Coast AQMD Rule 1108, "Cutback Asphalt" (2/1/85), and Rule 1108.1, "Emulsified Asphalt" (11/4/83), and conclude that Rule 227 has the same limits as the other districts' rules and implements current RACT. In 2008, the South Coast AQMD completed a detailed technology assessment for cutback asphalt and evaluated whether VOC emissions from cutback asphalt could be further limited during the ozone season by limiting its use to the fall and winter months when ozone formation is lowest or by replacing cutback asphalt completely with a surrogate water-based emulsion technology. South Coast AQMD included in its review an evaluation of rules adopted by other states, and concluded that SCAQMD Rule 1108 in tandem with Rule 1108.1 remain highly effective and did not recommend any changes to its rules for cutback asphalt. The EPA accepted the SCAQMD's evaluation.

We note that asphalt used for paving operations is composed of compacted aggregate and an asphalt binder. To be used for paving operations, the asphalt binder must be liquified using petroleum distillates (cutback asphalt) or with water and emulsifying agents (emulsified asphalt). The asphalt binder can also be liquified by heating to above 300 [o]F (hot mix asphalt) or, alternatively, by using a newer, different, technology that allows a lower manufacturing temperature (30  -  70 [o]F lower) called warm mix asphalt.[,]  Based on information compiled by Imperial County Air Pollution Control District and copied in Table 1 below, hot mix asphalt has a significantly lower emissions factor than cutback or emulsified asphalt. 

Table 1  -  Asphalt VOC Emission Factors (EF)

We note that today, roadway paving is generally performed using hot mix asphalt and that use of warm mix asphalt as an alternative to hot mix asphalt is expanding in some areas of the United States. The EPA has not revised its cutback asphalt CTG beyond limiting usage of cutback and emulsified asphalts, and the CTG does not mention hot or warm mix asphalts. Additional emission reductions may be possible if warm mix asphalt can be substituted for hot mix asphalt. However, based on a 2016 San Joaquin Valley Unified Air Pollution Control District report on its experiences with a warm mix asphalt pilot project, it appears that each asphalt paving operation will likely need to be evaluated on a case-by-case bases until paving contractors gain more experience with it.

Recommendations
The following recommendations are provided to improve the SIP and are not approvability issues. Our approval of NSAQMD's RACT SIP for the 1997 8-hour NAAQS included the following recommendations for the District to consider:

      Rule 227 Cutback and Emulsified Asphalt Paving Materials  -- 
:: We recommend adopting the rule provisions currently applied to the federal ozone
nonattainment area for the attainment areas within the District as well.
	:: The District may also want to consider the use of warm mix asphalt as appropriate.

For future RACT SIPs, the District may want to evaluate adopting a negative declaration for the cutback asphalt CTG if it can demonstrate that total cutback asphalt emissions in the ozone nonattainment area are less than 50 tpy,  the major source threshold for the District's current ozone nonattainment classification.

3.2.4 Rule 228, "Miscellaneous Metal and Plastic Parts Coating" 

NSAQMD's 2018 RACT SIP states that Rule 228:

was amended 4/25/11 and approved into the SIP for the 1997 standard 8/9/12. EPA has not taken action on the NSAQMD's September 27, 2011 negative declaration submittal for the plastic parts and heavier duty vehicle coatings portions of the CTG. Specifically, the District has no facilities that perform coating operations covered under the Miscellaneous Metal and Plastic Parts CTG (EPA-453/R-08-003) Table 3 Plastic Parts and Products, Table 4 Automotive/ Transportation and Business Machine Plastic Parts, or Table 6 Motor Vehicle Materials that equal or exceed the CTG's applicability threshold of 15 lbs./day actual emissions, or an equivalent level of 2.7 tons per 12-month rolling period, before consideration of controls. In addition, the District has no sources subject to this CTG under Table 5 Pleasure Craft Surface Coating operations. The NSAQMD still has no sources subject to the Tables 3  -  6 categories of the CTG for the 2008 NAAQS. For the metal parts coating portions, the only source in the nonattainment area that was originally subject (Serra Corporation on Bitney Springs Road) has closed. Nonetheless, the NSAQMD would like to keep the rule in the SIP for the 2008 standard in case a new source opens, as it is a fairly common source type in general. 

3.2.4.1 The EPA's evaluation

The EPA's 2008 CTG entitled "Control Techniques Guidelines for Miscellaneous Metal and Plastic Parts Coatings" (EPA-453/R-08-003) (MMPP) applies "at a facility where the total actual VOC emissions from all miscellaneous metal product and plastic parts surface coating operations, including related cleaning activities, at that facility are equal to or exceed 6.8 kg/day (15 lb/day), or an equivalent level of 2.7 tons per 12-month rolling period, before consideration of controls." We reviewed CARB's emissions inventory data for the years 2008  -  2017, and found that the two highest VOC emissions sources in the Western Nevada County ozone nonattainment area in this period emitted approximately 1.7 tpy, from 2008  -  2013 (Serra Corporation and Furniture by Thurston). We also note that consistent with NSAQMD's statement above that Serra Corporation has closed, we found that Serra Corporation has not appeared on CARB's emissions inventory database since 2012. Furniture by Thurston is also listed on CARB's emissions inventory website as emitting zero tpy since 2014. While CARB's 2017 emissions inventory shows Teichert Aggregate, in Truckee, California, emitting 1  -  2 tpy of VOC, this facility is outside of the ozone nonattainment area and therefore would not be subject to RACT. Also, CARB's emissions inventory database lists the Standard Industrial Classification (SIC) code for Teichert Aggregate as "1442", Construction Sand and Gravel. Based on its SIC code, we believe it is not likely to be subject to the MMPP CTG. 

In sum, we agree with the District's negative declarations for the source categories in Tables 3-6 of the MMPP CTG. Our evaluation also indicates that there are presently no sources in Western Nevada County that would meet or exceed the applicability threshold for the source category in Table 2 of the MMPP CTG. We therefore conclude that Rule 228 is not required for RACT at this time, and thus we believe that the District could elect to adopt a negative declaration for the entire 2008 MMPP CTG.

Nonetheless, since the District did not adopt a negative declaration for Table 2 of the MMPP CTG, we reviewed Rule 228, which is specific to Table 2 sources. We find that Rule 228 limits are generally consistent with or more stringent than the 2008 MMPP CTG, and that Rule 228 therefore implements RACT for the Table 2 source categories. Specifically, Rule 228's VOC limits for electric-insulating varnish (340 g/L or 2.8 lb/gal) and high performance architectural (420 g/L or 3.5 lb/gal) coatings are more stringent than the MMPP CTG's recommended limits (420 g/L and 740 g/L respectively). 

Recommendations
The following recommendations are provided to improve the SIP and are not approvability issues. The TSD for our 2012 approval of Rule 228 (amended 4/25/11) included the following recommendations for improvement the next time Rule 228 is amended: 

      Rule 228 Surface Coating of Metal Parts and Products  -- 
            :: Section 1.1 stipulates that this rule only regulates those portions of the District that are in nonattainment for any federal ambient air quality standard for ozone. We
            recommend that this rule regulate all sources of VOCs in metal coating operations in
            the District for equity in the District and to obtain additional VOC emissions reductions
            that may help the nonattainment areas.
            :: We recommend removing Section 1.2.6 and establishing VOC content limits for
            strippers such as contained in SCAQMD Rule 1107, Section (c)(3).
            :: The air dried VOC limits for Prefab Architectural Multi-Component and Prefab
            Architectural One-Component categories listed in Section 3.1 are consistent with the
            CTG values. However, SCAQMD's Rule 1107 has lower values for these categories,
            effective July 1, 2007. Please consider adopting these lower limits.
            :: The capture efficiency and control efficiency minimum of 90% required in Section 3.2.2 seems to be consistent with the overall efficiency of 90% suggested by the CTG.
            However, please consider clarifying the criteria in Section 3.2.2 to, "in lieu of complying
            with VOC content limits specified in Subsection 3.1 or the emission rate limitation in
            3.2.1, air pollution control equipment with an overall efficiency of 90% may be used..."
            Overall efficiency is defined as the product of capture efficiency and control efficiency.
            :: The work practices in Section 3.4 basically exempt the application of the work practices at facilities using control equipment as defined in Section 3.3.2, The CTG recommends that the work practices be applied to all controls affording a 90% overall efficiency. We suggest applying the work practices for solvent cleaning to those facilities that opt for the add-on control methods defined in Section 3.2.2.
            :: Please consider the following minor changes:
                   Change "does" to "do" in Section 1.2.1: ". . .VOC emissions (excluding exempt
            compounds) from all coatings do not exceed 2.7 tons..."
                   For consistency, add definitions in Section 2.0 for Airless Spray and Air-assisted
            Airless Spray which are listed in Section 3.3.
                   For clarity, provide the correct titles of ASTM E169 which is entitled "Standard
	Practices for General Techniques of [Ultraviolet-Visible Quantitative Analysis]."

3.3 RACT determination for major stationary sources 

As discussed above, RACT is required in all ozone nonattainment areas classified as Moderate or above for source categories covered by an EPA CTG document ("CTG sources") and for all sources that are not covered by a CTG document but which are "major sources", i.e., for NSAQMD, "non-CTG sources" that emit or have the potential to emit at least 50 tpy of NOx or VOC for a Serious ozone nonattainment area (or 100 tpy of NOx or VOCs for a Moderate ozone nonattainment area).

3.3.1 NSAQMD action

NSAQMD's 2018 RACT SIP states that "there are no major sources (that emit or have the potential to emit 50 tons or more per year) of ozone precursors located in the nonattainment area. The NSAQMD is therefore also adopting negative declarations that it has no major NOx or VOC sources in the ozone nonattainment area." NSAQMD's 2018 RACT SIP also states that "[t]he largest stationary source of ozone precursors in the Western Nevada County ozone nonattainment area is currently a gas station that emits under 2 tons of precursors per year."

3.3.2 The EPA's evaluation

As discussed above, the NSAQMD's 2018 RACT SIP evaluated whether the District had any major VOC/NOx sources emitting at least 50 tpy, and we evaluated it to determine whether it met the requirements for a Serious ozone nonattainment area as well as a Moderate ozone nonattainment area. We reviewed CARB's emissions inventory database for Nevada County for the years 2007  -  2017 and found there were no NOx or VOC stationary sources in the Western Nevada County ozone nonattainment area that approached the 50 tpy or 100 tpy thresholds for ozone nonattainment areas classified as Serious or Moderate, respectively. The highest NOx emissions sources during this period emitted 2.8 tpy (Vulcan Materials in 2007), and 3.8 tpy VOC (Furniture by Thurston in 2007). We also reviewed Nevada County's list of major employers and concluded that it did not have stationary source facilities that were generally expected to emit or have the potential to emit at least 50 tpy. We agree with the NSAQMD's statement that it has no major sources of VOC or NOx in the Western Nevada County ozone nonattainment area.

3.4 Negative Declarations

The preamble to the EPA's final rule to implement the 2008 ozone NAAQS states that "...RACT SIPs must contain adopted RACT regulations, certification where appropriate that existing provisions are RACT,[] and/or negative declarations that there are no sources in the nonattainment area covered by a specific CTG source category." In lieu of adopting RACT rules, Districts may adopt negative declarations for CTG source categories if there are no sources in the District's ozone nonattainment area covered by the CTG. A negative declaration is not required for ACTs or other non-CTG source categories.

3.4.1 NSAQMD action

Section 6.0 of the NSAQMD's 2018 RACT SIP states that "to the best of its knowledge and following a publicly noticed public hearing, []the District has no sources in the Western Nevada County Ozone Nonattainment Area subject to the CTGs listed as negative declarations in the following table. The District further declares that all negative declarations listed are current, adequate and applicable for the 2008 Ozone NAAQS."

3.4.2 The EPA's evaluation

We reviewed the District's table of CTGs and negative declarations. Based on our review of CARB's emissions inventory database, we agree there do not appear to be any stationary sources in the Western Nevada County ozone nonattainment area that are subject to those CTGs that NSAQMD annotated as "Negative Declaration for 2008 NAAQS" on pages 6-12 of its 2018 RACT SIP. Therefore, RACT is not required for the source categories corresponding to these CTGs.

4. SUMMARY and RECOMMENDATION

Table 2 below provides our summary listing of the CTGs and whether NSAQMD has rules or negative declarations addressing each CTG. Based on our evaluation of the NSAQMD 2018 RACT SIP, as discussed in detail above, we recommend approval of the NSAQMD 2018 RACT SIP as demonstrating that sources in the Western Nevada County ozone nonattainment area are subject to rules that implement RACT, satisfying this requirement under CAA Sections 182(b) and (f) for its current classification as Serious nonattainment area, as well as its previous classification as a Moderate nonattainment area.

Table 2: CTGs and NSAQMD Rules / Negative Declarations
     

CTG 
Title
                            Rule # claimed as RACT
                               Neg Dec submitted
                              New Rule submitted
                                Not addressed 
1
EPA-450/R-75-102

Design Criteria for Stage I Vapor Control  -  Gasoline Service Stations
214
78 FR 897

2
EPA-450/2-77-008

Surface Coating of Cans 

	X

3
EPA-450/2-77-008

Surface Coating of Coils 

	X

4
EPA-450/2-77-008

Surface Coating of Paper 

	X

5
EPA-450/2-77-008

Surface Coating of Fabric 

	X

6
EPA-450/2-77-008

Surface Coating of Automobiles and Light-Duty Trucks 

	X

7
EPA-450/2-77-022

Solvent Metal Cleaning 

	X

8
EPA-450/2-77-025

Refinery Vacuum Producing Systems, Wastewater Separators, and Process Unit Turnarounds 

	X

9
EPA-450/2-77-026

Tank Truck Gasoline Loading Terminals

	X

10
EPA-450/2-77-032

Surface Coating of Metal Furniture 

	X

11
EPA-450/2-77-033

Surface Coating of Insulation of Magnet Wire 

	X

12
EPA-450/2-77-034

Surface Coating of Large Appliances 

	X

13
EPA-450/2-77-035

Bulk Gasoline Plants

	X

14
EPA-450/2-77-036

Storage of Petroleum Liquids in Fixed-Roof Tanks

	X

15
EPA-450/2-77-037

Cutback Asphalt 
227
74 FR 56120
	

	
16
EPA-450/2-78-015

Surface Coating of Miscellaneous Metal Parts and Products 
228
77 FR 47536
	

17
EPA-450/2-78-029

Manufacture of Synthesized Pharmaceutical Products

	X

18
EPA-450/2-78-030

Manufacture of Pneumatic Rubber Tires

	X

19
EPA-450/2-78-032

Factory Surface Coating of Flat Wood Paneling 

	X

20
EPA-450/2-78-033

Graphic Arts-Rotogravure and Flexography

	X

21
EPA-450/2-78-036

Leaks from Petroleum Refinery Equipment

	X

22
EPA-450/2-78-047
Petroleum Liquid Storage in External Floating Roof Tanks

	X

23
EPA-450/2-78-051

Leaks from Gasoline Tank Trucks and Vapor Collection Systems
214
78 FR 897
	

24
EPA-450/3-82-009

Large Petroleum Dry Cleaners

	X

25
EPA-450/3-83-006

Leaks from Synthetic Organic Chemical Polymer and Resin Manufacturing Equipment

	X

26
EPA-450/3-83-007

Leaks from Natural Gas/Gasoline Processing Plants 

	X

27
EPA-450/3-83-008

Manufacture of High-Density Polyethylene, Polypropylene, and Polystyrene Resins 

	X

28
EPA-450/3-84-015

Air Oxidation Processes in Synthetic Organic Chemical Manufacturing Industry

	X

29
EPA-450/4-91-031

Reactor Processes and Distillation Operations in Synthetic Organic Chemical Manufacturing Industry

	X

30
EPA-453/R-96-007

Wood Furniture Manufacturing Operations

	X

31
EPA-453/R-94-032

61 FR 44050; 8/27/96
ACT Surface Coating at Shipbuilding and Ship Repair Facilities 
Shipbuilding and Ship Repair Operations (Surface Coating)

	X

32
EPA-453/R-97-004

59 FR 29216; 6/06/94
Aerospace MACT and Aerospace (CTG & MACT)

	X

33
EPA-453/R-06-001

Industrial Cleaning Solvents

	X

34
EPA-453/R-06-002
 
Offset Lithographic Printing and Letterpress Printing

	X

35
EPA-453/R-06-003

Flexible Package Printing

	X

36
EPA-453/R-06-004

Flat Wood Paneling Coatings

	X

37
EPA 453/R-07-003

Paper, Film, and Foil Coatings

	X

38
EPA 453/R-07-004

Large Appliance Coatings

	X

39
EPA 453/R-07-005

Metal Furniture Coatings

	X

40
EPA 453/R-08-003
Miscellaneous Metal Parts Coatings 
Table 2  -  Metal Parts and Products
228
77 FR 47536
	

41
EPA 453/R-08-003
Miscellaneous Metal Parts Coatings 
Table 3  -  Plastic Parts and Products

	X

42
EPA 453/R-08-003
Miscellaneous Metal Parts Coatings 
Table 4  -  Automotive/Transportation and Business Machine Plastic Parts

	X

43
EPA 453/R-08-003
Miscellaneous Metal Parts Coatings 
Table 5  -  Pleasure Craft Surface Coating 

	X

44
EPA 453/R-08-003
Miscellaneous Metal Parts Coatings 
Table 6  -  Motor Vehicle Materials

	X

45
EPA 453/R-08-004

Fiberglass Boat Manufacturing Materials 

	X

46
EPA 453/R-08-005

Miscellaneous Industrial Adhesives 

	X

47
EPA 453/R-08-006

Automobile and Light-Duty Truck Assembly Coatings

	X

48
EPA 453/B16-001

Oil and Natural Gas Industry 

	X

	
     

RACT for Major Non-CTG VOC/NOx Sources

Category
                           Rule(s) # claimed as RACT
                               Neg Dec submitted
                             New Rule(s) submitted
                                 Not addressed
Major non-CTG VOC sources

	
	X

Major non-CTG NOx sources

	X

5.0 REFERENCES 

 EPA Office of Air Quality Planning and Standards, "Issues Relating to VOC Regulation Cutpoints, Deficiencies, and Deviations," May 25, 1988 ("the Bluebook," revised January 11, 1990). https://archive.epa.gov/ttn/ozone/web/pdf/voc_bluebook.pdf. 
 EPA Region IX, "Guidance Document for Correcting Common VOC & Other Rule Deficiencies," August 21, 2001 ("the Little Bluebook").
 NSAQMD Reasonably Available Control Technology (RACT) State Implementation Plan (SIP) Revision for Western Nevada County 8-Hour Ozone Nonattainment Area, March 26, 2018. https://ww3.arb.ca.gov/planning/sip/planarea/wnc/2018ractsip.pdf. 
 Memorandum dated October 11, 1978 from G.T. Helms, Office of Air Quality Planning and Standards, U.S. EPA to EPA Regions I-X, Subject: "Questions and Answers on 1979 SIP Revisions," states the CTG limitations for cutback asphalt can be avoided in rural areas if it can be demonstrated that the total emissions from the use of cutback asphalt in the entire area does not exceed 100 tpy. https://www3.epa.gov/ttn/naaqs/aqmguide/collection/Doc_0032_VOC481011781.pdf. 
 Memorandum dated May 18, 2006, from William T. Harnett, Director, Air Quality Policy Division, to Regional Air Division Directors, Subject: "RACT Qs & As  -  Reasonably Available Control Technology (RACT): Questions and Answers." https://www.epa.gov/sites/production/files/2016-08/documents/ract_and_nsps_1dec1988.pdf.
 CARB, "Staff Report: Proposed Submission of California's Greenhouse Gas Emission Standards For Crude Oil And Natural Gas Facilities Into the California State Implementation Plan," September 21, 2018, ("CARB Staff Report") retrieved August 27, 2019, from https://ww2.arb.ca.gov/sites/default/files/2018-09/O%26G%20CTG%20-%20Staff%20Report.pdf. 
 California Department of Conservation, Division of Oil, Gas, and Geothermal Resources (DOGGR) Well Finder. https://maps.conservation.ca.gov/doggr/wellfinder/#openModal/-120.70916/39.29074/10. 
 CARB Pollution Mapping Tool. https://ww3.arb.ca.gov/ei/tools/pollution_map/#. 
 California Natural Gas Pipelines. Retrieved August 27, 2019, from https://ww2.energy.ca.gov/maps/infrastructure/Natural_Gas_Pipelines.pdf.   
 Letter dated March 22, 1979, from Walter C. Barber, Director, Office of Air Quality Planning and Standards, to Steven D. Jellinek, Chairman, Toxic Substances Priorities Committee, Subject: Regulation of Solvent Metal Cleaning Emissions under the Clean Air Act, retrieved August 27, 2019, from https://www3.epa.gov/ttn/naaqs/aqmguide/collection/Doc_0066_VOC150322791.pdf.
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 Memorandum dated August 17, 1979, from Richard G. Rhoads, Director, Director Control Programs Development Division, to Director, Air & Hazardous Materials Division, Regions I-X, "Evaluation of 10,000 gals/month Throughput Exemptions for Petroleum Marketing Operations," retrieved August 28, 2019, from https://www3.epa.gov/ttn/naaqs/aqmguide/collection/Doc_0081_VOC110817791.pdf. 
 Sacramento Metropolitan AQMD, Rule 448 Gasoline Transfer Into Stationary Storage Containers (2/26/09), retrieved August 28, 2019, from http://www.airquality.org/ProgramCoordination/Documents/rule448.pdf.
 EPA-453/R-08-003, Control Techniques Guidelines for Miscellaneous Metal and Plastic Parts Coatings, 3, retrieved August 28, 2019, from https://www3.epa.gov/airquality/ctg_act/200809_voc_epa453_r-08-003_misc_metal_plasticparts_coating.pdf.
 Natividad, Ivan, "Serra Corporation to close Nevada City manufacturing operations." The Union [Grass Valley], April 17, 2014, retrieved August 28, 2019, from https://www.theunion.com/news/business/serra-corporation-to-close-nevada-city-manufacturing-operations/.
 Natividad, Ivan, "Thurston Manufacturing to redistribute Grass Valley assets." The Union [Grass Valley], December 24, 2014, retrieved August 28, 2019, from https://www.theunion.com/news/local-news/thurston-manufacturing-to-redistribute-grass-valley-assets/. 
 CARB emission inventory site for Nevada County, retrieved August 28, 2019, from https://www.arb.ca.gov/app/emsinv/facinfo/faccrit.php?grp=1&dbyr=2017&all_fac=&sort=ROGHi&co_=29&ab_=&facid_=&dis_=&city_=&fsic_=&fname_=&fzip_=&chapis_only=&CERR=&dd=. 
 Major Employers of Nevada County, https://grassvalleychamber.com/wp-content/uploads/2014/08/GGVCC_RelocationPacket_MajorEmployers.pdf.
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 South Coast Air Quality Management District, "Technical Assessment for Rule 1108  -  Cutback Asphalt," June 2008.
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