Second Tier Review Recommendation Document for Emergency Engine Project Washington Department of Corrections Coyote Ridge Corrections Center Connel, Washington February 5, 2018

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Summary and Purpose This document presents Washington State Department of Ecology’s (Ecology’s) review and summary of the health risks from toxic air pollutants emitted by a new emergency diesel engine at the Deparment of Corrections’ (DOC) Coyote Ridge Correction Center (CRCC) in Connell, WA. Ecology concludes health risks are acceptable and recommends approval of the project. DOC submitted a permit application to Ecology’s Eastern Regional Office to replace an older 750 kW emergency generator at CRCC with a new 800 kW emergency generator. The generotor will be powered by a 1214 horsepower (905 kW) diesel engine that will be limited to no more than 50 hours of operation per year for maintenance and testing. Estimated diesel engine exhaust particulate (DEEP) emissions from this engine occur at a rate that causes ambient impacts in excess of a regulatory trigger level called an acceptable source impact level (ASIL). Therefore, a second tier review under WAC 173-460-090 was necessary to quantify the health risks posed by DOC’s increased emissions of DEEP. Ecology reviewed emissions and ambient impact estimates to conduct an assessment of lifetime increased cancer risks and chronic non-cancer hazards to individuals potentially exposed to DOC’s project-related DEEP emissions. Conclusions:

• The highest increased risk, approximately three in one million, occurs at location approximately 60 meters northeast of the proposed generator exhaust stack.

o The risk is likely overestimated as it assumes continuos lifetime exposure in an area where continuous exposure is unlikely.

• Chronic non-cancer hazards attributable to DOC’s increased DEEP emissions are not likely to result in adverse non-cancer health effects.

Recommendation:

• Because the increase in cancer risk attributable to the new diesel generator emissions alone is less than the maximum risk allowed by a second tier review, which is 10 in one million, and the non-cancer hazard is acceptable, the project is approvable under WAC 173-460-090.

This summary document presents Ecology’s assessment of DOC’s proposed emissions and other requirements under WAC 173-460.

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1. Streamlined Second Tier Review Processing and Approval Criteria

Ecology developed a streamlined second tier review process for smaller emergency engine projects (e.g., engine sizes ranging from 500-2000 bhp). Ecology recognized that these projects typically cause a minimal toxic air pollutant ambient impact. In the streamlined process, Ecology evaluates information submitted by the applicant and quantifies risks to determine if they are approvable under WAC 173-460-090. This evaluation satisfies the intent of WAC 173-460-090 without requiring an extensive and costly review. Under the streamlined second tier review process, Ecology may recommend approval of a project only if:

(a) The permitting authority has determined that other conditions for processing the NOC Order of Approval have been met, and has issued a preliminary approval order.

(b) Emission limits contained in the preliminary NOC approval order represent at least best available control technology for toxics (tBACT).

(c) The increase in emissions of TAPs is not likely to result in an increased cancer risk of more than one in one hundred thousand.

(d) Ecology determines that the noncancer hazard is acceptable.

2. DEEP health effects evaluation Diesel engines emit very small fine (<2.5 micrometers [µm]) and ultrafine (<0.1 µm) particles. These particles can easily enter deep into the lung when inhaled. Mounting evidence indicates that inhaling fine particles can cause or contribute to numerous adverse health effects. Studies of humans and animals exposed to diesel exhaust (measured as DEEP) indicate that diesel exhaust can cause both acute and chronic health effects including cancer. Ecology has summarized these health effects in “Concerns about Adverse Health Effects of Diesel Engine Emissions” available at <http://www.ecy.wa.gov/pubs/0802032.pdf>.

2.1. Toxicity reference values To quantify noncancer hazards and cancer risk from exposure to DEEP, quantitative toxicity values must be identified. Ecology identified toxicity values for DEEP from two agencies: the U.S. Environmental Protection Agency (EPA) (EPA, 2002; EPA, 2003), and California EPA’s Office of Environmental Health Hazard Assessment (OEHHA) (CalEPA, 1998). These toxicity values are derived from studies of animals that were exposed to a known amount (concentration) of DEEP, or from epidemiological studies of exposed humans, and are intended to represent a level at or below which adverse noncancer health effects are not expected, and a metric by which to quantify increased risk from exposure to a carcinogen. Table 1 shows the appropriate DEEP noncancer and cancer toxicity values.

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EPA’s reference concentration (RfC) and OEHHA’s reference exposure level (REL) for diesel engine exhaust (measured as DEEP) was derived from dose-response data on inflammation and changes in the lung from rat inhalation studies. Each agency established a level of 5 µg/m3 as the concentration of DEEP in air at which long-term exposure is not expected to cause adverse noncancer health effects. National Ambient Air Quality Standards (NAAQS) and other regulatory toxicological values for short- and intermediate-term exposure to particulate matter have been established, but values specifically for DEEP exposure at these intervals do not currently exist. OEHHA derived a unit risk factor (URF) for estimating cancer risk from exposure to DEEP. The URF is based on a meta-analysis of several epidemiological studies of humans occupationally exposed to DEEP. In these studies, DEEP exposure was estimated from measurements of elemental carbon and respirable particulate representing fresh diesel exhaust. The URF is expressed as the estimate of the plausible upper limit (i.e., the 95th percentile upper confidence interval) of cancer risk, assuming continuous lifetime exposure to a substance at a concentration of one microgram per cubic meter (1 µg/m3). It is expressed in units of inverse concentration [i.e., (µg/m3)-1]. OEHHA’s URF for DEEP is 0.0003 (µg/m3)-1 meaning that a lifetime of exposure to 1 µg/m3 of DEEP results in an increased individual cancer risk of 0.03 percent or a population cancer risk of 300 excess cancer cases per million people exposed.

Table 1. Toxicity Values Used to Assess and Quantify Non-cancer Hazard and Cancer Risk Pollutant Agency Noncancer Cancer

DEEP U.S. Environmental Protection Agency RfC = 5 µg/m3 N/A1

California EPA–Office of Environmental Health Hazard Assessment

Chronic REL = 5 µg/m3

URF = 0.0003 per µg/m3

1 EPA considers DEEP to be a probable human carcinogen, but has not established a cancer slope factor or URF.

2.2. Emissions and dispersion modeling Ecology estimated emissions of DEEP from the 905 kW emergency engine assuming:

• Fifty hours per year of engine operation for maintenance and readiness testing purposes • 4.7 hours per year of power interruption

o Based on Avista Energy’s System Average Interruption Duration Index (SAIDI) of 2.35 hrs per year with a safety factor of two applied.

• DEEP emitted at a rate of 182 g/hr consistent with particulate emission reqirements (0.2 g/kW-hr) for Tier II certified engines.

DOC’s consultant, Spring Environmental, used AERMOD with five years (2011-2015) of meteorological data from Pasco, WA to model dispersion of pollutants from the diesel engine exhaust stack. Spring Environmental submitted air dispersion modeling files to Ecology for review.

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2.3. Affected community/receptors

CRCC is a correction center located in an area surrounded largely by vacant and agricultural land. Air dispersion modeling indicated that DEEP emissions result in impacts above an ASIL over a small area of the CRCC facility (Figure 1). Potential recurring exposures are possible for inmates and DOC staff at CRCC.

2.4. Consideration of background diesel particulate exposures Chapter 173-460-090 WAC states, “background concentrations of TAPs will be considered as part of a second tier toxics review.” The word “background” is often used to describe exposures to chemicals that come from existing sources, or sources other than those being proposed. Ecology determined a background DEEP concentration in the CRCC area (census tract 53021020800) of about 0.185 ug/m3 based on EPA’s 2011 national-scale air toxics assessment (NATA).

2.5. Increased cancer risk Current regulatory practice assumes that a very small dose of a carcinogen will give a very small cancer risk. Cancer risk estimates are, therefore, not yes/no answers but measures of chance (probability). Such measures, however uncertain, are useful in determining the magnitude of a cancer threat because any level of a carcinogenic contaminant carries an associated risk. The validity of this approach for all cancer-causing chemicals is not clear. Some evidence suggests that certain chemicals considered carcinogenic must exceed a threshold of tolerance before initiating cancer. For such chemicals, risk estimates are not appropriate. Guidelines on cancer risk from EPA reflect the potential that thresholds for some carcinogenesis exist. However, EPA still assumes no threshold unless sufficient data indicate otherwise. Cancer risk is estimated by determining the concentration of DEEP at each receptor point and multiplying it by its respective unit risk factor (URF). Because URFs are based on a continuous exposure over a 70-year lifetime, exposure duration and exposure frequency are important considerations. EPA guidance (EPA, 2009) recommends use of the following formula to determine cancer risk from inahalation exposure:

Risk = CAir x URF x EF1 x EF2 x ED AT

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Where:

Parameter Description Value Based on Receptor Type Units Worst-case (continuous)

DOC Worker

CAir Concentration in air at the receptor

maximum = 0.011 μg/m3

URF Unit Risk Factor 0.0003 (μg/m3)-1 EF1 Exposure Frequency 365 250 days per year EF2 Exposure Frequency 24 8 hours per day ED Exposure Duration

70 40

years

AT Averaging Time 25550 days Table 2, shows the estimated DOC-specific and cumulative cancer risk per million at the maximally impacted receptor. The highest increase in risks attributable to DOC’s emissions is 3 per million1 and occurs at a 60 meters northeast of the engine exhaust stack. The increased lifetime risk posed by DOC’s proposed emissions is relatively low compared to the existing “background” risk of about 56 per million from existing on- and non-road diesel particulate sources in the area.

Table 2. Estimated Increased Cancer Risk Attributable to Project- related DEEP Emissions and Background Exposures

Attributable to:

Risk Per Million from DEEP Exposure at maximally impacted receptor

Worst-case continuous exposre DOC worker

DOC Project (800 kW emergency generator)

3.4 0.4

Background 55.5 7.2

Cumulative 58.9 7.6

2.6. Noncancer hazard 1 Number per million represents an upper-bound theoretical estimate of the number of excess cancers that might result in an exposed population of one million people compared to an unexposed population of one million people. Alternatively, an individual’s increase in risk of one in one million means a person’s chance of getting cancer in their lifetime increases by one in one-million or 0.0001 percent.

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In order to evaluate the potential for non-cancer adverse health effects that may result from exposure to air pollutants, exposure concentrations at each receptor location are compared to relevant non-cancer toxicological values (i.e., RfC, REL). If a concentration exceeds the RfC or REL, this indicates only the potential for adverse health effects. The magnitude of this potential can be inferred from the degree to which this value is exceeded. This comparison is known as a hazard quotient (HQ) and is given by the equation below: HQ = concentration of pollutant in air (µg/m3) RfC or REL A HQ of one or less indicates that the exposure to a substance is not likely to result in adverse non-cancer health effects. As the HQ increases above one, the probability of human health effects increases by an undefined amount. However, it should be noted that a HQ above one is not necessarily indicative of health impacts due to the application of uncertainty factors in deriving toxicological reference values (e.g., RfC and REL). Ecology evaluated chronic noncancer hazards associated with long-term exposure to DEEP emitted from DOC’s engine (Table 3). Hazard quotients were lower than unity (one) for the maximally impacted receptors’ exposure to DOC -related and cumulative DEEP. This indicates that chronic noncancer hazards are not likely to occur as a result of exposure to DEEP at and near the CRCC.

Table 3. Non-cancer hazard quotients (HQs) Attributable to Project- related DEEP Emissions and Background Exposures

Receptors

Maximum Annual Avg. DEEP Concentration (µg/m3)

DEEP Chronic REL

(µg/m3)

HQ

DOC Project -related

NATA 2011 estimated ambient

concentration census tract 53021020800 Total

DOC Project -related

NATA 2011 Total

Maximimally Exposed Receptor

0.0104 0.185 0.196 5 <0.01 0.04 0.04

3. Conclusions and Recommendation Conclusions:

• The highest increased risk, approximately three in one million, occurs at location approximately 60 meters northeast of the proposed generator exhaust stack.

o The risk is likely overestimated as it assumes continuos lifetime exposure. • Chronic non-cancer hazards attributable to DOC’s increased DEEP emissions are not

likely to result in adverse non-cancer health effects.

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Recommendation:

• Because the increase in cancer risk attributable to the diesel generator emissions alone is less than the maximum risk allowed by a second tier review, which is 10 in one million, and the non-cancer hazard is acceptable, the project is approvable under WAC 173-460-090.

4. References CalEPA, California Environmental Protection Agency: Air Resources Board and Office of

Environmental Health Hazard Assessment, Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant, 1998, Available at: <http://www.arb.ca.gov/toxics/dieseltac/staffrpt.pdf>.

EPA, United States Environmental Protection Agency, Health Assessment Document for Diesel

Exhaust, EPA/600/8-90/057F, May 2002, Available at: <http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060>.

------, United States Environmental Protection Agency, Integrated Risk Information System

record for Diesel Exhaust, last revised February 28, 2003, Available at: <http://cfpub.epa.gov/ncea/iris/index.cfm?fuseaction=iris.showQuickView&substance_nmbr=0642>.

------, United States Environmental Protection Agency, Risk Assessment Guidance for Superfund

Volume I: Human Health Evaluation Manual (Part F, Supplemental Guidance for Inhalation Risk Assessment), EPA-540-R-070-002, January 2009, Available at: <https://www.epa.gov/sites/production/files/2015-09/documents/partf_200901_final.pdf>

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Figure 1. Estimated annual DEEP concentrations relative to the ASIL in the area impacted by emissions from DOC”s proposed 800 kW generator at Coyote Ridge.