United States Environmental Protection Agency Air and Energy Engineering Research Laboratory Research Triangle Park NC 27711 Research and Development EPA/600/S8-88/084 Nov. 1 988 x°/EPA Project Summary Preliminary Diagnostic Procedures for Radon Control B. H. Turk, J. Harrison, R. J. Prill, and R. G. Sextro Analytical procedures for diagnosing radon entry mechanisms into buildings are described. These diagnostic methods are generally based on the premise that pressure-driven flow of radon-bearing soil gas into buildings is the most significant source of radon in houses with elevated concentrations, although procedures to determine the contributions of other potential sources (e.g., building materials and potable water) to indoor airborne concentrations are also included. Flowcharts are presented that develop a logical se- quence of events in the diagnostic pro- cess, including problem diagnosis, selection and implementation of mitiga- tion systems, and post-mitigation evalua- tion. The initial problem assessment pro- cedures rely on an organized set of measurements to characterize the struc- ture, the surrounding soil, and the like- ly entry pathways from the soil into the building. The measurement procedures, described in detail, include radon grab sampling under both naturally and mechanically depressurized conditions, visual and instrumental analyses of air movement at various substructure loca- tions, building leakage area tests, and soil characterization methods. Post- mitigation evaluation procedures are also described. Samples of various data forms and test logs are provided. This Project Summary was developed by EPA's Air and Energy Engineering Research Laboratory, Research Triangle Park, NC, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction With the discovery of high indoor radon (Rn-222) concentrations in a significant number of houses since the late 1970s, it has become important to develop a better understanding of the mechanisms of radon movement into and accumulation in buildings and suitable methods for control- ling or eliminating the accumulations. In general, earlier research has found that the most significant source of indoor radon is the soil surrounding the building shell from which radon migrates into the building, transported by the pressure-driven flow of soil gas. Factors influencing the radon en- try rate include indoor-outdoor air temper- ature differences, wind loading, soil characteristics, construction details of the building superstructure and substructure, and the coupling between the soil and the substructure. To further investigate radon control techniques, the U. S. Environmental Pro- tection Agency (EPA), the Department of Energy (DOE), and the New Jersey Depart- ment of Environmental Protection (NJDEP) funded an intensive study in 14 northern New Jersey houses. The research was con- ducted by the Lawrence Berkeley Laboratory (LBL) in seven houses and col- laboratively by Oak Ridge National Laboratory and Princeton University in the remaining seven houses. The following overall objectives were established for the project: - Extend the understanding of the fun- damentals of soil gas flow and radon entry into buildings and improve the basic knowledge of factors that in- fluence the entry rate. - Refine and develop analysis pro- cedures for diagnosing radon entry mechanisms and selecting appropriate control systems. - Develop and demonstrate practical radon mitigation techniques for selected basement/crawl space houses. ------- The research plan to meet the above ob- jectives had four main components: 1) house and site characterization measurements, 2) baseline and continuous monitoring of environmental and building parameters, 3) diagnostic procedure development, and 4) installation and opera- tion of selected mitigation techniques. Diagnostic Procedures This report focuses primarily on the se- cond objective: i.e., the preliminary development of diagnostic procedures. Diagnostic procedures are defined here as organized and logical measurements, tests, and observations that are necessary for identifying the specific means by which radon enters and accumulates in a par- ticular structure. These procedures should point the way to a suitable system or techni- que for controlling indoor radon levels. These procedures may also be applied as follow-up measurements, tests, and obser- vations useful in optimizing mitigation system performance. This development ef- fort builds on the previous, on-going, and generally unpublished work of others, in- cluding Scott, Tappan, Ericson, and Bren- nan, as well as on the basic scientific understanding developed by Nazaroff, Nero, Tanner, and others. This report pro- vides a format for refinement, reduction and interpretation of the measurements and observations necessary for selecting an ap- propriately designed, effective, and economical system for controlling indoor radon concentrations in single-family detached houses. Table 1 lists the diagnostic research measurements and procedures discussed in this report. The premise for many of the diagnostic procedures developed and discussed here is that the pressure-driven flow of radon bearing soil gas is the most significant source of radon in houses with elevated concentrations. However, other potential sources of radon, such as water and building materials are also included in the diagnostic procedures. Figure 1 outlines the mitigation process framework govern- ing the use of diagnostic measurements. The procedures described here rely on individual site-specific observations and short term measurements of air flow, pressure differentials, radon concentrations and near-building material characteristics. The measurements are then used to iden- tify primary radon sources (water, building materials, soil) and most probable radon entry points and mechanisms. Tools and in- struments listed in Table 2 are necessary to conduct the diagnostic procedures discussed in this report. The report Table 1. Project Measurements and Procedures > Visual Inspection of House • Alpha Scintillation Cell Radon Grab Samples ' Sub-slab and Wall Air Flow Communication Tests < Air Infiltration Leakage Tests ' Appliance Depressurization Effects < Soil Characterization < Radon in Water < Radon Flux from Building Materials Problem Diagnosis • Measure heating season indoor radon concentrations • Evaluate non-soil sources 9 Characterize structure and soils and identify entry points Selection and Implementation of Mitigation Systems • Consider results of diagnostic measurements • Review options for mitigation • Develop and implement mitigation plan Post-Mitigation Evaluation • Monitor indoor air concentrations • Measure mitigation system operating parameters Successful — ~ — (Improve System Efficiency) Figure 1. General plan for radon control assumes that the reader has prior ex- perience with flow and pressure measur- ing devices, and alpha particle counting techniques. The full report describes the Unsuccessful (Modify System] — or (Install Additional Options) diagnostic procedures forms used for data recording and a sample application of diagnostics in a house studied as part of the aforementioned comprehensive study. ------- Table 2. Instruments and Equipment Radon Grab Sampling: Air Leakage and Flow Measurements: Soils Characterization: Inspection Equipment: Tools: Miscellaneous: Alpha scintillation cells Portable photomultiplier tube counting station Hand pump with sample tube and 0.8 cm filter Compressed air or nitrogen for cell flushing Vacuum pump for evacuating cells (70 cm, 27 in. Hg vacuum) Calibrated-flow blower door (6800 m3fr', 4000 cfm @ 5 Pa) Pitot tubes (electronic or liquid-filled manometers: 1-50 kPa) Hot wire anemometer (with temperature sensing element) Smoke tubes Industrial vacuum cleaner (170 m3fr', 700 cfm @ 2 m HzO pressure) 1.5 m (5 ft) flow sections of: 7.6 cm (3 in.) PVC with coupler 15 cm (6 in.) galvanized duct Non-toxic tracer gas (SFe, Freon-12) Tracer gas detection instrument Soil core and auger samplers 3/4 in. reversible electric drill Soil air permeability device Sliding hammers Various diameter drill bits, include some attached 1.5 m (5 ft) long extensions 1.5 m (5 ft) long probe pipes Stiff wires Telescoping mirrors Portable gamma spectrometer Fiber optics scope 3/8 in. variable-speed hand drill Masonry bits 1/2 in. hammer drill Impact bits Pocket flashlights Hand sledge Pry bar Pipe wrench Locking pliers Adjustable wrenches Portable lights Step ladders Long blade screwdriver Forms Inspection hole plugs Epoxy-based mortar patch or hydraulic cement Duct tape Duct seal 0.3, 0.6, 1 cm (1/8, 1/4, 3/8 in.) diameter tubing Various-sized hypodermic needles Plastic film Thermometers: electronic and mercury-filled glass Silicone sealant have been developed for identifying the sources of indoor radon problems and selecting systems for controlling radon. In houses where the recommended remedial measures have been installed, based on the diagnostic measurements, radon con- centrations have fallen below the guideline of 4 pCi/L However, a rigorous process for selecting successful, optimized systems has not yet been developed for widespread use by technicians and contractors. Three new, and largely unvalidated techniques are presented that may assist in determining contributions to indoor radon levels from the domestic water supply and building materials and the approximate distribution of air infiltration leakage area in a structure. This document reports on progress in research still underway. Addi- tional data and observations are being made that may support, augment, or in some cases invalidate, some of the conclu- sions discussed here. Other diagnostic techniques and tools under invesitgation in this and other studies include: use of tracer gases to quantify en- trainment of building air into subsurface ventilation systems; creating flow and pressure maps for hollow block foundation walls; quantifying and apportioning subsur- face ventilation from below slabs and from within block walls; estimating outside air ventilation that enters along the soil/house interface; and development of a radon "snif- fer" with faster recovery time between samples taken from test holes, entry points, and indoor air. Another new method will at- tempt to challenge an installed mitigation system by using a depressurization fan to gradually increase substructure depressuri- zation and thereby determine the system failure point. The report discusses details of the various diagnostic methods, techniques, and procedures currently under develop- ment, and provides in flowchart form a logical sequence of steps that will guide the reader through the measurement and evaluation mitigation process. The em- phasis of this system of diagnosis is for research purposes and is intended to serve as the basis for development of approaches for general commercial applications. The report provides a house-specific ex- ample of the above diagnostic procedures with the purpose of demonstrating and evaluating their utility in the mitigation pro- cess. Preliminary diagnostic procedures ------- B. Turk, J. Harrison, R. Prill, and R. Sextro are with the University of California, Berkeley, CA 94720. David C. Sanchez is the EPA Project Officer (see below). The complete report, entitled "Preliminary Diagnostic Procedures for Radon Control," (Order No. PB 88-225 115/AS; Cost: $14.95, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 U.S. OFFICIAL MAIL" Environmental Protection Agency Information Cincinnati OH 45268 [ NOV30'83 "~ V , . . - — . -v^t; l-f \\j^f ^PENALTV U.S.POSIAGE 1- IPRIVATE ™ /ri;3* - 0.25 ~: 6251! 03 1 L Penalty for Private Use $300 EPA/600/S8-88/084 0000329 PS W S Efl¥IR PROTECTION AGENCY REGION 5 LIBRARY ^30 S OEARBORK STRfET CHICAGO IL 60604 ------- |