13 Part2RadonReportCAVE042120FTC2.pdf

7881 Shaffer Parkway Littleton, CO 80127 Office: 720.283.8974 Fax: 720.283.8666

April 21, 2020

Mr. Jon H. Holbrook, AIA, LEEP AP

Associate Vice President | Senior Federal Program Manager

HDR

1670 Broadway, Suite 3400

Denver, Colorado 80202

Jon.Holbrook@hdrinc.com

Subject: REVISED - Radon Screening at Carlsbad National Caverns, Elevator Shafts 1 & 2.

Landmark Project No. 19117.001.001.

Dear Mr. Holbrook:

Landmark Environmental, Inc. (Landmark) is pleased to provide this report for a radon screening at

Carlsbad National Caverns (CAVE) Elevators 1 and 2 in Carlsbad, New Mexico.

Background Information

Radon is an invisible, odorless, tasteless, radioactive gas. Particularly high radon levels occur in regions where the soil or rock is rich in uranium. Radon can enter the indoor air and accumulate in confined air spaces, such as basements and crawl spaces, and be inhaled by a building’s occupants.

The resulting radiation dose increases the risk of lung cancer.

The National Park Service provided Landmark with a study completed by the National Institute for

Occupational Safety and Health (NIOSH) that was originally completed in 2014-2015 and revised in

20191. This study included long-term radon analysis. They placed the first set of samples for analysis from August 2014 to December 2014. They placed a second set of samples for December 2014 through

April 2015. The results from this study stated the average in the elevator shafts in the August through

December sampling event was 66.7 picocuries per liter air (pCi/L) and the December through April event was 21.7 pCi/L. Generally speaking, the visitor center levels were lower than those in the cavern.

The cavern levels were lower in the winter sample than in the sample that included summer months.

The reason the Cavern has higher radon levels in the summer is because air exchange rate in the cavern is very low in the summer, once every 18 days in July2 or ~5% of the air in the cavern per summer day. It is higher in the winter as the warmer air from the cavern rises out to the cooler outdoor air.

1 NIOSH [2019]. Exposure to radon and radon progeny in an underground tourist cavern and its connected buildings. By Zwack LM, Brueck SE, Anderson JL, Hammond DR. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Health Hazard Evaluation Report 2014-0158-3345, https://www.cdc.gov/niosh/hhe/reports/pdfs/2014-0158- 3345.pdf.

2 Cheng YS, Chen TR, Wasiolek PT, Van Engen A [1997]. Radon and radon progeny in the Carlsbad Caverns. Aerosol Sci Technol 26(1):74–92, https://doi.org/10.1080/02786829708965416.

Project No. 19117.001.001 2 of 3

Higher exchange rates lead to lower levels of radon daughter products in the air (unattached fraction) primarily through dilution from fresh air make-up.

The purpose of Landmark’s testing was to assess the radon levels within the elevator shaft to provide background information to contractors who will be working in the shaft. The Occupational Safety and

Health Administration (OSHA) established its radon limits shortly after the promulgation of the

Occupational Health and Safety Act and it is set to a 100 pCi/L average concentration over 40 hours in any consecutive seven days. This value is based on the 1969 version of Appendix B to 10 CFR Part

20. In 1996, OSHA updated the act to include the current Nuclear Regulatory Commission’s (NRC) limits on workers under the age of 18. Under OSHA, workers under 18 are not allowed to be exposed to over an average of 3 pCi/L averaged over a 40-hour workweek.

Field Activities

Landmark’s industrial hygienist, Mrs. Brandy Howard, met onsite with Joshua Appleton from the

National Park Service. Mr. Appleton operated the elevator car in service mode so radon samples could be set at the beam which is half-way down the elevator shaft between the two cars. Landmark also placed samples in the elevator pit (Cave Level) and in the elevator lobby on the service side (Visitor

Center Level).

Samples were collected using liquid scintillation vials. Sampling was performed in duplicate at each location. The vials were opened to begin sample collection at the subject property on March 17, 2020 and retrieved on March 19, 2020 approximately 48 hours after they were initially opened. The vials were then sealed and sent to the laboratory using appropriate chain-of-custody procedures. Radon data are presented in Attachment A.

Laboratory Activities

The radon samples were submitted for analysis under chain-of-custody to EMSL Analytical, Inc., located in Cinnaminson, New Jersey. EMSL is accredited for radon analysis by the National Radon

Safety Board (Lab Code ARL6006).

Radon analysis was performed by EMSL using a liquid scintillation radon detector and results were measured on a liquid scintillation counter using approved Environmental Protection Agency (EPA) testing protocols for Radon in Air testing. A copy of the laboratory results is included in Attachment

A.

Findings and Conclusions

As expected from historical results, the results were higher in the elevator pit (Cave Level) than in the elevator service lobby (Visitor Center Level). The elevator lobby on the service entrance (Visitor

Center Level) samples averaged 32.2 pCi/L. The sample taken half-way down the elevator shaft averaged 49.5 pCi/L. The sample from the elevator pit (Cave Level) averaged 54.0 pCi/L. All of these results are below the 100 pCi/L limit established by OSHA and are consistent with the previous studies

Project No. 19117.001.001 3 of 3 results. Staff working in the elevator shaft are expected to be below the OSHA radon limit during their construction activities.

In addition to the OSHA radon standard, people exposed to radon must also comply with the OSHA whole-body ionizing radiation dose limits. The whole-body ionizing radiation dose limit established by OSHA is 1.25 roentgen equivalent man (rem) per quarter. Landmark did not perform modeling or sampling for comparison against this standard. This is because the sample that Landmark collected only represents approximately two days of exposure and the NIOSH report indicates there are seasonal fluctuations in radon levels and whole-body ionization radiation.

Due to these seasonal fluctuations, the NIOSH study guidelines are more appropriate to use for developing administrative controls, such as worker rotations. During summer months, the NIOSH study indicated that personnel should not spend more than 225 hours in the cavern per quarter (about

5.5 weeks before rotating to another job at another location without elevated ionizing radiation exposure). These recommendations were based on an average radon concentration of 69.7 pCi/L in the cavern with an unattached fraction of radon daughter products of 0.60. The NIOSH study indicated that the elevator shaft during the summer had a similar average radon concentration of 66.7 pCi/L.

During the winter, the cavern averaged 25.0 pCi/L in the NIOSH study and they recommended no more than 665 hours per quarter be spent by workers in the Cavern. The 665 hours per quarter equates to essentially no restrictions since full-time work at 40 hours per week is approximately 500 hours per quarter. The same study listed the elevator shaft as averaging 21.7 pCi/L during the same period of time. These limits would be a conservative starting estimate for designing a worker rotation schedule for construction staff that are working full-time in the elevator shaft.

A valid alternative to worker rotation during the summer months when the hours are more restrictive would be to lower exposures within the elevator shaft by deploying ventilation for the duration of the project. The NIOSH report indicated that the outdoor air at the site averages 0.4 pCi/L in both the winter and the summer sampling events. If outdoor make-up air were supplied to the elevator shaft and ventilation arranged to ensure circulation throughout the elevator shaft, the resulting concentrations of radon and the unattached fraction of daughter products will likely be low enough not to require any additional controls (such as worker rotation schedules) during the project. We understand that shaft ventilation has been implemented previously on other projects and could be implemented again.

Limitations

Services performed by Landmark on this project were performed in a competent and professional manner in accordance with sound consulting and contracting practices and procedures. Landmark performed radon assessments in a manner consistent with the level of care and expertise exercised by members of the industrial hygiene profession using trained and experienced personnel. This report is intended only to provide an indication of the identified environmental conditions associated with the subject property. It is based only on the observations made and data collected at the property at the time of the assessment as well as on data obtained. This report is not to be considered a statement of clearance. Landmark provides no assurances and assumes no responsibility for property conditions or

Project No. 19117.001.001 4 of 3 activities that are outside the scope of the services, or for changes to property conditions, or regulatory requirements which may apply after completion of the services by Landmark.

Landmark appreciates the opportunity to assist HDR with this important project. If you have any questions or require any additional information, please do not hesitate to call me at 720.283.8974.

Respectfully, Landmark Environmental, Inc.

Brandy Howard, CIH, CSP

Project Manager

This report was reviewed by:

Thomas S. Norman, PE

Senior Program Manager

Attachment A – Radon Laboratory Analytical Results

Attachment A

RADON LABORATORY ANALYTICAL RESULTS