United States Environmental Protection Agency Office of Air and Energy Engineering Research and Research Laboratory Development Research Triangle Park, NC 27711 EPA/600/9-91/005 March 1991 Radon Mitigation Research Update Introduction Project Highlights 1 • Indoor Radon Research Program • Florida Radon Program • Measurements in Previously Mitigated Houses • Manual Updates • New Technical Manual 1991 International Symposium on Radon and Radon Reduction Technology _„„__„„—_...„ • AEERL Papers Update of RMB Papers and Reports .... EPA Regional Offices Response Form ».._.»«„.«......«««.......„. The Radon Mitigation Research Update is the second in a series of research summaries intended to provide recent information about EPA's radon mitigation research activities by the Air and Energy Engineering Research Laboratory (AEERL) and to compile a list- ing of recent Radon Mitigation Branch (RMB) research findings. AEERL plans to publish future updates ap- proximately two times a year. If you would like more information about specific research activities or programs, you may contact the appropriate RMB project officer at MD-54, U.S. EPA, AEERL, Research Triangle Park, NC 27711, or at the number listed below. RMB Contacts Mike Osbome, Branch Chief (919)5414113 • EPA radon mitigation research and development program A.B. "Chick" Craig (919)541-2824 • Senior Physical Scientist - Radon Tim Dyess (919)541-2802 • Radon resistant new construction Bruce Harris (919)541-7807 • Radon diagnostics and measurement tech- nology Bruce Henschel (919)541-4112 • Radon mitigation in existing houses Kelly Leovic (919)541-7717 • Radon mitigation in schools Ron Mosley (919)541-7865 • Radon data analysis John Ruppersberger (919) 541-2432 • Radon barriers and block permeability David Sanchez (919)541-2979 • Mechanisms of radon entry and Florida Radon Research Program Project Highlights Indoor Radon Research Program—Strategic Plan AEERL first embarked on an aggressive radon mitigation develop- ment and demonstration research program in 1984. Since that time, research has evolved from a program which focused on demonstrat- ing mitigation techniques in houses with highly elevated radon levels, to a multi-faceted research, development, and demonstration program concerned with reducing radon to near-ambient levels (less than 1 pCi/L) in existing houses, new houses, and schools across the coun- try. This expanded effort responds to EPA's public health mission and the 1988 Indoor Radon Abatement Act's mandate to reduce radon- related health risk by reducing indoor radon to near-ambient levels. To meet the demands of this expanded effort, AEERL has recently developed a 3-year Strategic Plan for the Indoor Radon Research Program that integrates the activities of five otherwise separate program areas—1) innovative and supporting technology, 2) existing attached and unattached houses, 3) new houses (including pollution prevention), 4) schools, and 5) technology transfer—into one com- prehensive research effort. An increased emphasis has been placed on innovative/supporting research in an effort to accelerate improvements in technology, lower 1 the cost of technology, and facilitate the delivery of this technology to a larger and broader audience. The Indoor Radon Research Program has five areas of major empha- sis: 1) developing new and improved radon reduction methods through a better understanding of fundamentals, 2) de-emphasizing the demonstration of currently available radon mitigation technology in existing and new houses, 3) increasing the emphasis on mitigation system durability assess- ments and operating cost analyses, 4) continuing to identify, develop, and demonstrate radon mitiga- tion options for schools and non-residential child care facilities, and 5) supplying a greater variety of audience-specific technology transfer products. Utilizing this integrated approach, concepts developed in the Inno- vative and Support Technology area will be demonstrated in existing houses, new houses, and/or schools and other large buildings. Prod- ucts resulting from each of these efforts will then be incorporated into technical guidance documents. Printed on Recycled Paper ------- Florida Radon Research Program RMB has coordinated and completed the delivery of recommenda- tions and draft technical support documents to the Florida Depart- ment of Community Affairs for Standards for Radon-resistant Con- struction and Mitigation. The results of this effort will be published in 18 reports covering recommendations for 1) improved floor barriers, 2) subslab depressurization systems, 3) HVAC specifica- tions, 4) fill material specifications, and S) performance criteria. Data gathered by the Florida Radon Research Program is available through a central Geographic Information System (CIS) data base maintained by the Geoplan Center of the University of Florida. Program and project planning for continuation of the EPA/Florida interagency research agreement has also begun. These plans include the initiation of a 2-year research effort to enhance the technical basis for the five task areas listed above, and to begin work on the development of a radon potential mapping basis for application of construction and mitigation standards. Work in all task areas will be undertaken in unoccupied research houses with development verified in newly constructed houses. Problem assessment and building characterization studies for large buildings will start in FY 91. (For additional information on this program contact D. Sanchez, Project Officer.) Measurements In Previously Mitigated Houses RMB is conducting measurements in previously mitigated (18 months or longer) test houses in an effort to establish the long-term effective- ness and durability of various mitigation systems. Researchers have placed 6-month Alpha Track Detectors (ATDs) in a number of basement and slab-on-grade houses, mitigated by EPA or EPA contractors, to gather data on post-mitigation radon levels. Plans are under way to initiate similar activities in a large number of houses mitigated by private sector companies. The results of this study will allow RMB researchers to identify radon mitigation systems/strategies that are not effectively maintaining indoor radon levels below 4 pCi/L- Study findings will also help identify mitiga- tion systems/strategies which show the greatest potential for reduc- ing indoor radon levels to near-ambient levels. Follow-up research will focus on identifying equipment and installa- tion problems as well as house and soil characteristics which may have contributed to system failure. Research findings will be made available through AEERL publications and in future issues of Radon Mitigation Research Update. (For additional information contact B. Harris, Project Officer.) Update of Technical Manuals AEERL is currently updating a number of EPA technical guidance manuals to better assist in the dissemination of the most timely and accurate radon reduction research information. These updated manu- als are scheduled for release later this year and include Radon Reduction for Detached Houses (Technical Manual), and Radon- Resistant Construction Techniques for New Residential Construction (Technical Guidance). New Technical Manual AEERL will also publish the first edition of EPA's Radon-Resistant New School Construction Manual. This new manual will be based largely on RMB's recent experience in existing schools and previous experience with radon-resistant new house construction techniques. It will provide the most up-to-date information available on the design of radon-resistant/easy-to-mitigate new school buildings. 1991 International Symposium on Radon and Radon Reduction Technology Final plans are being made for the 1991 International Symposium on Radon and Radon Reduction Technology "A New Decade of Progress" to be held April 2-5 at the Adam's Mark Hotel in Philadelphia, PA. EPA will co-sponsor the event with the Conference of Radiation Control Program Directors (CRCPD). This is the third such confer- ence to serve as a forum for the exchange of technical information. The program includes 77 oral and 52 poster presentations in addition to 13 invited papers. Over 600 representatives from radon mitigation companies, local, state, and federal governments, equipment manufacturers, academia, and research and development firms are expected to attend. The following agenda provides a summary of the conference's four session days: Tuesday, April 2 Session I: Government Programs and Policies Relating to Radon Session II: Radon-Related Health Studies Poster Session: All Posters Relating to Sessions I, n, and in Wednesday, April 3 Session HI: Measurement Methods Session IV: Radon Reduction Methods Session V: Radon Entry Dynamics Session VI: Radon Surveys Poster Session: All Posters Relating to Sessions IV, V, VI, and Vn Thursday, April 4 Session VII: State Programs and Policies Relating to Radon Session VDI: Radon Prevention in New Construction Session DC: Radon Occurrence in the Natural Environment Poster Session: All Posters Relating to Sessions VHI. IX, and X Friday, April 5 Session X: Radon in Schools and Large Buildings If you would like more information about the symposium, please contact Pat Heightchew, CRCPD, Inc., 205 Capital Avenue, Frank- fort, KY 40601, (502) 227-4543. On-site registration will be avail- able from 4 to 9 pjn. Monday, April 1, and from 7 a.m. to 5 p.m. Tuesday through Thursday. ------- AEERL Papers This section lists and briefly describes the 18 RMB oral papers and poster papers which will be presented at the 1991 International Symposium. RMB Project Officers and lead authors are listed for each paper. For addi- tional information on these research activi- ties, please refer to the symposium pre-prints (available with symposium registration) or contact the appropriate RMB Project Officer listed on page 1. Measurement Methods Predicting Long-term Indoor Radon Lev- els from Short-term Measurements: Evaluation of a Method Involving Tem- perature Correction; R.B. Mosley, Project Officer, and T.A. Reddy. Oral Paper Daily averages of year-long continuous radon measurements in three houses were used to present a method for temperature-correcting single short-term measurements of indoor radon in order to predict long-term averages. The thermal stack effect was demonstrated to have the most important single influence on radon concentrations. The method was found to reduce the uncertainty in estimated annual averages of radon concentrations sig- nificantly in one house, moderately in the second, and marginally in the third. Correlation Between Short-term and Long-term Indoor Radon Concentrations in Florida Houses; D.C. Sanchez, Project Officer, and S.E. McDonough. Poster Pa- per Eighty study homes, representative of typical Florida housing construction, with indoor radon concentrations in the 2-20 pCi/L range, are being simultaneously monitored using long-term and short-term monitors. Data have been analyzed to isolate system- atic seasonal variations and to derive confi- dence limits for predicted long-term (annual) averages from single or multiple short-term measurements. Thresholds have been deter- mined below which a single short-term mea- surement can provide specific confidence that the long-term average radon level does not exceed 4 pCi/L. These results have been incorporated into Florida's draft building standards. Soil Gas Measurement Technologies; D.C. Sanchez, Project Officer, and H.E. Rec- tor. Poster Paper This paper discusses soil-based radon and radium measurement technologies capable of providing useful information for evaluat- ing land radon potentials. Findings indicate that, while the use of soil gas measurements to estimate radon potentials is still evolving, both radium- and soil-gas-based measure- ments can help identify land areas warrant- ing special attention and consideration for radon-resistant construction. Radon Reduction Methods Causes of Elevated Post-mitigation Radon Concentrations in Basement Houses Hav- ing Extremely High Pre-mitigation Val- ues; D.B. Henschel, Project Officer, and A.G. Scott. Oral Paper Forty Pennsylvania basement houses with 1985-87 pre-mitigation radon levels in the 50 to 600 pCi/L range were reevaluated in 1989-90. The primary single cause of re- sidual (post-mitigation) elevated radon lev- els in houses using active soil depressuriza- tion (ASD) was found to be reentrainment of high-radon fan exhaust In houses using block wall depressurization systems, inadequate sub-slab depressurization appeared to be the major cause of problems. For other than ASD systems, inherent limitations within the systems are commonly the primary single cause of residual levels. Airborne radon re- sulting from radon in well water was an important secondary contributor in some houses. Natural Basement Ventilation as a Radon Mitigation Technique; R.B. Mosley, Project Officer, and A. Cavallo. Oral Pa- per The effectiveness of natural ventilation in reducing indoor radon levels was studied in two basement houses. The study found that a factor of two increase in the ventilation rate (opening basement windows) corresponded to as much as a factor of eight reduction in radon concentration. The researchers found a corresponding, but much smaller, decrease in the pressure differentials (radon driving forces) across the basement slabs. Control Of Radon Releases in Indoor Commercial Water Treatment; B. Harris, Project Officer, and A.B. Craig. Poster Paper Municipal treatment facilities, industrial process facilities, and other water treatment facilities may be at risk for high indoor radon levels. Water laden with relatively low levels of radon (400 to 600 pCi/L), when used in high volume commercial operations, may release enough radon to result in indoor levels in excess of 100 to 300 pCi/L in treatment rooms and adjoining offices. Elevated radon levels identified in the Fish and Wildlife Service's National Fish Hatch- eries were controlled by vacuum-stripping the incoming water and exhausting the radon outdoors. Hooding and exhausting air from immediately around discharge points also proved to be successful in reducing indoor levels. Radon Mitigation Failure Modes; D.B. Harris, Project Officer, and WM. Yeager. Poster Paper Residential mitigation systems fail for a va- riety of reasons and some failures may not be immediately recognized by residents. This study identified three primary failure catego- ries (design flaws, component problems, and occupant activities) and reviewed examples of failure modes in each category. Results indicate that some failures could be avoided if mitigators would design systems to mini- mize failures, install system monitors, and instruct homeowners on continued system maintenance. Radon Entry Dynamics Radon Entry into Dwellings Through Concrete Floors; D.C. Sanchez, Project Officer, and K.K. Nielson. Oral Paper Porosities, radon diffusion coefficients, and air permeability coefficients were measured for typical Florida slab-on-grade housing ce- ment mixes. Findings suggest that radon dif- fusion through an intact slab may account for indoor radon concentrations of 2 pCi/L if greater than 3,000 pCi/L exists in the sur- rounding soils. Radium concentrations of 5 pCi/g in the concrete similarly may account for more than 1 pCi/L of indoor radon. Dif- fusion measurements also exhibited a corre- lation with the water/cement ratio of the concretes. Model Calculations of the Interaction of a Soil Depressurization System with the Radon Entry Process; R.B. Mosley, Project Officer. Poster Paper This study uses a simplified analytical model of radon transport and entry into houses to estimate the influence of a mitigation system on the entry process. Modifications of the diffusive flux and the entry rate into the building by the action of the mitigation sys- tem are estimated in order to determine the total effect on emission of radon to the atmo- sphere. A Modeling Examination Of Parameters Affecting Radon and Soil Gas Entry into Florida-style Slab-on-grade Houses; D.C. Sanchez, Project Officer, and R.G. Sextro. Poster Paper The influence of soil, backfill, and construc- tion characteristics on radon and soil gas entry is examined using a two-dimensional finite difference model employing cylindri- cal symmetry. At a constant building depres- surization, steady state pressure, flow, and radon concentration fields were predicted. The model predicts that changes in backfill permeability will have significant effects on radon entry, while changes in block wall permeability are somewhat offset by in- creased flow and entry through other struc- tural gaps. Soil Gas and Radon Entry Potentials for Slab-On-Grade Houses; D.B. Henschel, Project Officer, and B.H. Turk. Poster Paper A simple model is used to address the impor- tance of subslab communications testing, in- cluding measurements of radon concentra- ------- dons and soil gas flows through slab test holes, in determining the number and loca- tion of active subslab depiessurization (ASD) suction holes. Findings suggest that pipes for ASD systems should be located along the perimeter of slabs and only at areas of rela- tively high radon entry potentials. The model also suggests that three or fewer properly placed suction points will often reduce in- door radon levels to below 2 pCi/L, even in problem houses. Radon Prevention In New Construction Building Radon Mitigation into Inacces- sible Crawlspace New Residential Con- struction; B. Harris and A.B. Craig, Project Officers, and J. Haynes. Oral Pa- per Single, duplex, and quadruple* buildings were constructed utilizing a below-grade wood floor construction over an inaccessible crawl space due to highly expansive soils. Initial studies demonstrated the need for complete sealing of the floor system until a negative pressure could be maintained under each comer of the floor (at least 2.5 Pa). Early measurements indicated radon levels of about 100 pCi/L in the unmitigated crawl space. Tests in the first buildings completed showed all units below 25 pCi/L except for one unit where the depressurization fan had been turned off. This unit measured 16 pCi/L and dropped to below 25 pCi/L when the fan was activated. The Effect of Subslab Aggregate Size on Pressure Field Extension; A.B. Craig, Project Officer, and K. Gadsby. Oral Pa- per The effects of particle size and particle size distribution on sub-slab pressure field exten- sion (PFE) were evaluated using laboratory tests simulating conditions existing under slabs. Findings indicate that PFE is propor- tional to the average stone size (the smaller the stone size, the less the PFE), the stone size distribution (the narrower the stone size distribution, the greater the void volume and hence the PFE), and the shape of the stone (the smoother the shape of the stone, the lower the void volume and hence the PFE). Preliminary Results Of HVAC System Modifications To Control Indoor Radon Concentrations; TJV1. Dyess, Project Offi- cer, and T.M. Brennan. Poster Paper Preliminary testing in one energy-efficient house indicates that residential forced-air furnaces can be used to pressurize basements and prevent radon entry. By adding a supply air duct in the basement and modifying the HVAC unit to run continuously on low speed, 300 cfm of air was supplied to the basement maintaining +4 Pa relative to outdoors. The average radon levels dropped from 143 to 1.2 pCi/L. Further research will analyze the economic impact of these modifications and determine their viability as a low cost alter- native to sub-slab depressurization in new construction. Radon In Schools HVAC System Complications and Con- trols for Radon Reduction in School Buildings; K.W. Leovic, Project Officer. Oral Paper Initial data collected in four schools in Colo- rado, Maryland, Virginia, and Washington State confirm that, when outdoor air supply is increased using HVAC systems (forced air or unit ventilator), radon levels can be re- duced. Depending on HVAC system design and initial radon levels, this approach may or may not be able to reduce levels to below 4 pCi/L. Table 1 illustrates reductions achieved by pressurization of classrooms (using exist- ing HVAC systems) in one Washington State school. Note that the classroom-to-hall doors had to be kept closed for the unit ventilators to reduce average levels to below 4 pCi/L, al- though radon spikes (as high as 25 pCi/L) still occurred. TabU 1. Average Radon Levels In Waikington School During One Week Normal Operation Test Operation Average Radon Location pCUL (max) Room 139 2.6 Room 140 S3 Room 141 4& Average 42 (27) (29) (32) (29) Time Door Closed 97 92 88 92 Average Radon pCUL (max) 12 32 2J 22 (17) <7) (25) (16) Time Door Closed (*) 76 74 75 75 Subslab Radon Sniff. August 90 pCUL 400 500 700 533 Research over the next year will be focused on determining optimal HVAC system op- erations and limitations of pressurization. Long-term research will include a compari- son of HVAC modification and active subslab depressurization in the same schools. Design of Radon-Resistant and Easy-To- Mitigate New School Buildings; A.B. Craig, Project Officer, and K.W. Leovic. Oral Paper Recent experience in existing schools, new house construction, and limited experience in new school construction indicates that radon resistant features can and should be incorporated into new school buildings in high risk areas. Radon-resistant features work by reducing the potential for radon (soil gas) entry and facilitating cost effective post-con- struction mitigation. Pre-construction features include: designing, installing, and operating the HVAC system to pressurize the building providing adequate makeup air for building exhausts; laying down a minimum of 4 in. of clean, coarse subslab aggregate; limiting subslab barriers to air movement; and rough- ing in subslab depressurization points. Design and Application of Active Soil De- pressurization Systems in School Build- ings; K.W. Leovic, Project Officer. Poster Paper Recent research on active subslab depres- surization (ASD) systems in two Kentucky and two Maine schools indicates that: 1) schools with low permeability material (i.e., sand) under the slab may require higher suc- tion fans to adequately depressurize the subslab area; 2) utility tunnel depressurization may be an effective and relatively inexpen- sive technique if the tunnels are not too leaky and do not contain asbestos; 3) ASD systems are typically preferred to passive systems in existing schools to maximize radon reduc- tions; and 4) subslab pressure field extension (based on measurements conducted in one school) is greater when suction is applied to an interior point rather than from the building exterior. A Comparison of Radon Mitigation Op- tions for Crawlspace School Buildings; K.W. Leovic, Project Officer, B.E. Pyle. Poster Paper Research in one Tennessee school constructed over a crawl space indicates that sub-mem- brane depressurization is the most effective technology for reducing radon levels in both the classrooms and the crawl space. Crawl space depressurization was effective in re- ducing levels in the classrooms but increased levels in the crawl space by a factor of two to three. Both pressurization and natural venti- lation of the crawl space were found to be less effective technologies than sub-mem- brane depressurization or crawl space de- pressurization. ------- RMB Papers and Reports Since Last Update Reports Since Last Update: "Testing of Indoor Radon Reduction Tech- niques in Central Ohio Houses: Phase 2 (Winter 1988-89)," Findlay, W.O., A. Robertson, and A.G. Scott, submitted to EPA by Acres International Corp., EPA-600/8- 90-050, May 1990 (NTIS No. PB90- 222704).* 'Testing of Indoor Radon Reduction Tech- niques in 19 Maryland Houses," Gilroy, D.G., and W.M. Kaschak. submitted to EPA by COM Federal Programs Corp., EPA-600/8- 90-056, June 1990 (NTIS No. PB90-244393). "Radon Mitigation Studies: Nashville Dem- onstration," Pyle, B.E., and A.D. Williamson, submitted to EPA by Southern Research In- stitute, EPA-600/8-90-061, July 1990 (NTIS No. PB90-257791). "Interim Radon-Resistant Construction Guidelines for Use in Florida—1989," Pugh, T.D., submitted to EPA by Florida A&M University, EPA-600/8-90-062, August 1990 (NTIS No. PB90-265349). "Engineering Design Criteria for Sub-slab Depressurization Systems in Low-perme- ability Soils," Fowler, C.S., et aL, submitted to EPA by Southern Research Institute, EPA- 600/8-90-063, August 1990 (NTIS No. PB90- 257767). "Investigation of Radon Entry and Effective- ness of Mitigation Measures in Seven Houses in New Jersey," Dudney, C.S., et al., submit- ted to EPA by DOEADak Ridge National Laboratory, EPA-600/7-90-016, August 1990 (NTIS No. DE89016676). "Identification of Candidate Houses for the North Florida Portion of the Florida Radon Mitigation Project," Roessler, G.S., et al., submitted to EPA by University of Florida, EPA-600/8-90-070, September 1990 (NTIS No. PB90-274077). "Summary of EPA's Radon Reduction Re- search in Schools During 1989-90," Leovic, K.W., prepared in-house by EPA, EPA-600/ 8-90-072, October 1990 (NTIS No. PB91- 102038). 'Testing of Indoor Radon Reduction Tech- niques in Basement Houses Having Adjoin- ing Wings," Messing, M., submitted to EPA by Infiltec, EPA-600/8-90-076, November 1990 (NTIS No. PB91-125831). "Follow-Up Annual Alpha-Track Monitor- ing in 40 Eastern Pennsylvania Houses with Indoor Radon Reduction Systems (Decem- ber 1988-December 1989)," Scott, A.G., and A. Robertson, submitted to EPA by American ATCON, EPA-600/8-90-081, November 1990 (NTIS No. PB91-127779). Symposia Presentations: "Building HVAC/Foundation Diagnostics for Radon Mitigation in Schools: Part 2," Leovic, K.W., D. B. Harris, and A. B. Craig, pre- sented at Indoor Air 1990, Toronto, Canada, August 1990. "Planning for Quality in Radon Mitigation," Ford, J. S., and B. Harris, presented at Indoor Air 1990, Toronto, Canada, August 1990. "Radon Diagnostics for Schools," Leovic, K.W., A. B. Craig, and D. B. Harris, pre- sented at 83rd Annual AWMA Meeting, Pittsburgh, PA, June 24-29, 1990. * All reports with NTIS members are available (prepaid) from the National Technical Informa- tion Service, 5285 Port Royal Road, Spring- field, VA 22161 (phone 703/487-4650). EPA Regional Offices Region 1 (CT,ME,MA,NH,R1,VT) JFK Federal Building Boston, MA 02203 (617) 565^1502 Region 2 (NJ, NY) 26 Federal Plaza New York, NY 10278 (212) 264-4418 Region 3 (DE, DC. MD, PA, VA, WV) 841 Chestnut Building Philadelphia, PA 19107 (215) 597-8320 Region 4 (AL, FL, GA, KY, MS, NC, SC, TN) 345CourtlandSt.N.E. Atlanta, GA 30365 (404) 347-3907 Region 5 (IL, IN. MI, MN, OH. WI) 230 South Dearborn St. Chicago, IL 60604 From IN, MI. OH, MN, and WI (800) 621-8431 FromIL (800)572-2515 Region 6 (AR.LA.NM.OK.TX) 1445 Ross Avenue Dallas, TX 75202 (214) 655-7223 Region 7 (IA, KS, MO. NE) 726 Minnesota Avenue Kansas City. KS 66101 (913)551-7020 Region 8 (CO, MT, ND, SD, UT, WY) 999 18th Street Denver Place, Suite 500 Denver, CO 80202-2405 (303) 293-1709 Region 9 (AZ,CA,HI,NV) 75 Hawthorne San Francisco, CA 94105 (415) 744-1045 Region 10 (AK, ID, OR, WA) 1200 Sixth Avenue Seattle, WA 98101 (206)442-7660 EPA Headquarters 401 M Street S.W. Washington, D.C. 20460 (202)475-9605 Radon Hotline Number 1 (800) SOS-RADON ------- Response Form AEERL welcomes your comments and suggestions regarding its programs and reports. To forward your remarks or to be included on our mailing list for future publications, please complete the following information and return it to: Kelly Leovic, MD-54, U.S. EPA, AEERL, Research Triangle Park, NC 27711. Name Business/Profession Mailing Address City State ZIP Type of Business/Profession G I would like to be included on AEERL mailing list Comments United States Air and Energy Engineering FIRST CLASS Environmental Protection Research Laboratory MD-54 POSTAGE & FEES PAID Agency Research Triangle Park. NC 27711 EPA PERMIT NO. G-35 Official Business Penalty for Private Use $300 EPA/600/9-91/005 V ------- |