DOCUMENT RESUME

ED 315 880 EA 021 607

TITLE Radon Reduction Techniques in Schools: InterimTechnical Guidance.

INSTITUTION Environmental Protection Agency, Washington, D. C.REPORT NO EPA-520/1-89-020PUB DATE Oct 89NOTE 54p.; For related document, see EA 021 602.PUB TYPE Guides - Non-Classroom Use (055) -- Reports -

Research /Technical (143)

EDRS PRICE MF01/PC03 Plus Postage.DESCRIPTORS Air Flow; Air Pollution; Climate Control;

*Educational Facilities Improvement; ElementarySecondary Education; Environmental Standards;*Facility Requirements; Government Publications;Guidelines; *Prevention; *School Buildings; *SchoolSafety; Ventilation

IDENTIFIERS *Radon

ABSTRACTThis technical document is intended to assist school

facilities maintenance personnel in the selection, design, andoperation of radon reduction systems in schools. The guidancecontained in this document is based largely on research conducted in1987 and 1988 in schools located in Maryland and Virginia.Researchers from the United States Environmental Protection Agency(EPA) adapted radon reduction techniques proven successful inresidential housing and installed them in eight schools. Resultsindicate that radon mitigation and diagnostic techniques developedfor houses can be applied successfully in these schools. Correctiveactions and costs for radon reduction will be school specific endwill depend on the initial radon level; the extent of the radonproblem in the school; the school design and construction; and thedesign and operation of the heating, ventilating, andair-conditioning (HVAC) system. Covered in the document arebackground information on radon and radon mitigation experience,important school building characteristics relative to radon entry andmitigation, problem analysis, radon diagnostic testing, and radonmitigation system design and installation. Appendices includetechnical information, case studies, and lists of State Radon Officesand EPA Regional Radiation Program Offices. (MLF)

*********************x*********************************%***************Reproductions supplied by EDRS are the best that can be made

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EPA 520/1.89-020

RADON REDUCTION TECHNIQUES IN SCHOOLS

BEST COPY AVAILABLE

Interim Technical Guidance

Office of Radiation ProgramsOffice of Air and Radiation

andAir and Energy Engineering Research Laboratory

Office of Research and Development

United States Environmental Protection AgencyWashington. DC

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October 1989

U.S. DEPARTMENT OF EDUCATIONOffice of Educational Research and improvement

EDUCATIONAL RESOURCES INFORMATIONCENTER (ERIC)

is document hell been reprOduced asreceived from the Person or organizationoriginating aMinor changes have been made to improvereproduction quality

Points of view Or opinion* Stated in this doCu-ment do not necessarily represent officialOERI position or policy

EPA DISCLAIMER NOTICE

The U.S. Environmental Protection Agency (EPA) strives to provide accurate, complete, and usefulinformation. However, neither EPA nor any person contributing to the prep..-stion of this documentmakes any warranty, impressed or implied, with respect to the usefulness or enecttveness of anyinformation, method, or process disclosed in this document.

Mention of firms, trade names, or commercial products in this document does not constituteendorsement or recommendation for use.

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ACKNOWLEDGMENTS

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The information contained in this technical document is based largely on research conducted inWashington County, Maryland, by the Air and Energy Engineering Research Laboratory (AEERL) ofEPA's Office of Research and Development and their contractor, INFILTEC The research wasconducted with the assistance of H. Winger of the Washington County Schools (Maryland).

A.B. Craig and KW. Leovic AEERL and D. W. Saum of INFILTEC contributed to authorship of thisdocument. F. L Blair in the Radon Division Jf EPA's Office of Radiation Programs (ORP) served asWork Assignment Manager for contractor support. J. Harrison also of ORP's Radon Division providedsubstantive information and comments. Of the contributors outside of EPA, we are particularly indebtedto T. Brennan of Camroden Associates and W. A. Turner of HIM= Associates for their input.Drafts of this document have been reviewed by a large number of individuals in the Government and inthe private and academic sectors. Comments from these reviewers in addition to those from theindividuals listed above have helped significantly to improve the completeness, accuracy, and clarity ofthe document. The following reviewers offered substantial input: A. Penny of the National Institute ofStandards and Technology; P.A. Giardina and L. G. Koehler of EPA Region 2; W.E. Bellanger of EPARegion 3; F. P. Wagner of EPA Region 4; R. Dye of EPA Region 7; L. Feldt, J. Hoornbeek, D.Murane, and L Salmon of ORP's Radon Division; J. Puskins of ORP's Analysis and Support Division;C. Phillips of Fairfax County Public Schools (Virginia); D. Shiftlet of Prince George's County Schools(Maryland); H. M. Mardis of Environmental Research and Technology, Inc.; R. J. Shaughnessy of theUniversity of Tulsa; T. Meehan of Safe-Aire; 0. Bushong and R. McNally of EPA's Office of ToxicSubstance's Asbestos Program. Technical editing was provided by W. W. Whelan of AEERL and I.McKnight of ORP.

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CONTENTS

PageACKNOWLEDGMENTS iii

1 "NTRODUCTION1.1 Purpose1.2 Additional Sources of Information1.3 Radon Facts 2

er,

2 RADON MITIGATION 5

2.1 Radon Entry 5 .2.2 Radon Variations Within Schools 62.3 Radon Mitigation Techniques 6

3 ANALYZING THE PROBLEM 9

4 CRITICAL SCHOOL BUILDING COMPONENTS 11

4.1 School Substructures 11 .4.2 HVAC Systems 124.3 Location of Utility Lines 14

5 DESIGN AND INSTALLATION OF SUBSLAB DEPRESSURIZATION(SSD) SYSTEMS IS

5.1 Application 155.2 Disgnostic Toting 155.3 Design and Installation 17

6 OTHER APPROACHES TO RADON REDUCTION 23

6.1 Classroom Pressurization6.2 Increasing Ventilation 246.3 Crawl Space Depressurization 24

7 SPECIAL CONSIDERATIONS 25

7.1 Building Codes 257.2 Worker Protection 257.3 Asbestos 25

REFERENCES 27

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APPENDIX A: TECHNICAL INFORMATION 29A.1 Using Construction Documents 29A2 Fan and Pipe Selection30A.3 Dispostic Measurement Tools 32A.4 Installation Tools33as School SSD Installation Variations 33

APPENDIX B: SCHOOL MMGA'T1ON CASE STUDIES 35School A: Prince Oeorge's County, MD 35School B: Washington County, MD 36School C: Washington County, MD 40School D: Washington County, MD 41School E: Fairfax County, VA42School F: Washington County, MD 44School 0: Arlington County, VA 45School H: Washington County, MD 46

APPENDIX C: STATE RADON OFFICES AND EPA REGIONAL RADIATION PROGRAlv:OFFICES49State Radon Offices49EPA Regional OM=53

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1. INTRODUCTION

1.1 PURPOSE

This technical document is intended to assistschool facilities maintenance personnel, Stateofficials, and other interested persons in theselection, design, and operation of radonreduction systems in schools. School officialsshould work in conjunction with a personexperienced in radon mitigation, preferably inschools, to diagnose the problem and determinewhich mitigation options are feasible. Schoolofficials can contact their State Radon Office orEPA Regional Office for guidance on selectinga qualified radon mitigation contractor. (SeeAppendix C.)

The guidance contained in this document isbased largely on research conducted in 1987 and1988 in schools located in Maryland andVirginia. In these initial efforts, researchersfrom the U.S. Environmental Protection Agency(EPA) adapted radon reduction techniquesproven successful in residential housing andinstalled them in eight schools. Results indicatethat radon mitigation and diagnostic techniquesdeveloped for houses can be applied successfullyin these schools. The applicability of thesemitigation approaches to other schools willdepend on the unique characteristics of eachschool.

Seca le school design, construction, andoperation patterns vary considerably, it is notalways possible to recommend 'standard'corrective actions that apply to all schools.Costs for radon reduction will also be schoolspecific and will depend on the initial radonlevel, the extent of the radon problem in theschool, the school design and construction, thedesign .dnd opetadoa of the besting, ventilating,and air-conditiosiag (HVAC) system, and theability of the Wind maintenallee personnel toparticipate in the diagnosis and mitigation ofthe radon problem. With the guidance of anexperienced radon mitigator, maintenancepersonnel may be able to install radon reductionsystems themselves.

This technical document covers backgroundinformation on radon and radon mitigation

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experience, important school buildingcharacteristics relative to radon entry andmitigation, problem analysis, radon diagnostictesting, and radon mitigation system design andinstallation. Appendices include technicalinformation, case studies of the Maryland andVirginia schools mitigated, and lists of SlateRadon Offices and EPA Regional RadiationProgram Offices.

It is important to understand that this ispreliminary guidance. A major researchprogram is under way in the Air and EnergyEngineering Research Laboratory in EPA'sOffice of Research and Development, andguidance on recommended radon reductionactions for schools will be updated as soon aspossible.

13 ADDITIONAL SOURCES OFINFORMATION

The publications listed below are available fromState Radon Offices or from EPA RegionalOffices. (See Appendix C.)

PUBLICATIONS ON RADON IN SCHOOLS

For guidance on how to measure radon levels inschools, you should consult "RadonMeasurements in Schools - An Interim Report"(EPA 520/1-89-010).

OThER PUBLICATIONS ON RADON

EPA has been studying the effectiveness ofvarious methods of reducing radonconcentrations in houses. Although this work isnot yet complete, considerable progress hasbeen made over the last several years, and anumber of EPA publications have been issued.A general familiarity with these publications onradon reduction in houses will be useful inunderstanding and reducing elevated radonlevels in school buildings.

'A Citizen's Guide to Radon: What It Is AndWhat To Do About It' (EPA OPA-86004)provides general background information for the

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homeowner on radon and its associated healthrisks. It should be noted that this guide isbeing updated, and the neat edition should beavailable in mic14990.

"Radon Reduction Methods: A Homeowner'sGuide' (Second and Third Editions)(OPA-87410 and OPA49-010) describe ingeneral terms the various radon reductionmethods available to homeowners.

"Radon Reduction Techniques for DetachedHouses: Technical Guidance" (Second Edition)(EPA/625/5471019) is a reference manualproviding information on the sources of radonand its health effects as well as detailedguidance on the selection, design, installation,and operation of radon reduction systems.

"Application of Radon Reduction Methods"(EPA/625/548/024) supplements the secondedition of the technical manual (above) as adecision guidance document directing the userthrough the steps of diagnosing a radonproblem and selecting a radon reductionapproach. Mitigation system design, installation,and operation are also detailed.

"Radon Reduction in New Construction, AnInterim Guide' (EPA °PA-81.009) and"Radon-Resistant Residential New Construction"(EPA400/8-88-087) provide information onradon prevention techniques for newconstruction.

1.3 RADON FACTS

1.3.1 81.4.211.2111

Radon Is a C0101141111, odorless, and tastelessradioactive gas which results from the decay ofuranium. Since =Man occurs naturally insmall quantities in most rocks and soli, radon iscontinually released into soil gm, undergroundwater, and outdoor air. Radon is chemicallyinert, and it moves freely without combiningwith other materials. In outdoor air the radonemitted from the soil is quickly diluted to verylow concentrations. However, relatively highconcentrations of radon can accumulate insidebuildings if radon-containing soil gas infiltrates

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into the building through openings such ascracks, building joints, and utility penetrations.Normal building ventilation may dilute theincoming radon gas, but depending on the sodgas radon levels and the amount of soil gasearl', the ranee oancec Jation in the buildingmay accumulate to high levels. Since radonsource suengths vary and radon entry routes areso unpredictable. testing each building is theonly practical way to determine the extent ofthe problem.

EPA currently recommends taking action toreduce radon levels in homes where the annualaverage concentration of radon exceeds 4picocuries per liter (pCi/L). (As a comparison.dverage outdoor radon concentrations tend torange from about 0.1 to 0.2 pCi/L.) The greaterthe reduction in Mon, the greater thereduction in health risk. Consequently, aneffort should be made to reduce radon levels inall buildings as far below 4 pCl/L as possible.It should also be noted that the 1988 IndoorRadon Abatement Act establishes as a nationallongterm goal that the air within buildings beas free of radon as the air outside of thebuildings.

1.3.2 Health

Radon differs from most other carcinogens inthat human epidemiological evidence linksradon to lung cancer, and this evidence is wellsupported by laboratory studies andexperimental research. Although uncertaintiesremain and considerable research is continuingin this geld, the health risks of radon have beenclearly recognized by the National Academy ofSciences, the U. S. Public Health Service, andEPA.

Lung cancer is the only health risk whichsignificant data clearly associate with radon.Radon gas decays into other radioactiveCements (often referred to as radon decayproducts or radon progeny) which can lodge inthe lungs. Bombardment of sensitive lung tissueby alpha radiation released from the decayproducts can increase the risk of lung cancer. Itis estimated that radon causes roughly 20,000lung cancers each year in the United States.

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It should be emphasized thDt estimates of thenumber of lung cancan resulting from radonvary widely, but ens the lowest estimaterepresents the largest 011161) of lung cancer fornon-smokers. Not everyone exposed to elevatedlevels of radon will develop lung cancer.However, most scientists believe that children

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are at an equal or greater risk from exposure toradon than adults and that smokers are at agreater risk from exposure to radon thannonsmokers. There is also consensus amongscientists that the risk of developing lung cancerincreases as the concentration and length ofexposure

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2. RADON MITIGATION

Since 1984, when elevated levels of indoorradon were discovered in the Reading Prongarea of Pennsylvania, many thousands of houseshave had radon reduction systems installed. Inmany areas of the United States, it is notuncommon to And a contractor with housemitigation experience. !n tact, many statesmaintain lists of radon mitigation contractors.(See Appendix C for a list of State RadonOffices.)

Radon mitigation experience in schools isrelatively recent. However, initial researchindicates that radon reduction technologiesproven successful in houses are applicable tosome schools, The applicability of thesemitigation approaches to other schools willdepend on the unique characteristic of eachschool.

2.1 RADQN ENTRY

Radon normally enters a building from soil gasthat is drawn in by pressure differentialsbetween the soil surrounding the substructureand the building interior. U the buildinginterior is at a lower pressure than the soilsurrounding the substructure and radon ispresent in the soil, the radon can be pulled inthrough cracks and openings that are in contactwith the soil. The amount of radon in a givenclassroom will depend on the level of radon inthe underlying material, the ease with Mild* theradon moves as a component of the soil gasthrough the soil, the magnitude and direction ofthe pressure differentials, and the number andsize of the radon entry routes.

2.1.1 causes e[ lt+aatnre Different1als

Pressure differestbis that contribute to radonentry can result from operation of an HVACsystem under °maims that cause negativepressures (in the building relative to the subslabarea), indooributdoor temperature differences(including the 'stack effect'), use of appliancesor other mechanical devices that depressurizethe building, and wind.

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HVAC systems in schools and other largebuildings vary considerably and tend to have amuch greater impact on radon levels than doheating and sir conditioning systems in houses.If the HVAC system induces a negative pressurein the building relative to the subslab area.radon can be pulled into the building throughfloor and wall cracks or other openings incontact with the soil.

Even if the HVAC system does not contributeto pressure differentials in the building, thermalstack effects can induce localized negativepressure at the base of the building causingmdonscontaining soil gas to be pulled into theschool. As air inside the structure is heated, itbecomes less dense, and rises, exiting outthrough openings in the top of the structure.Cooler air is drawn into the building to replacethe warm air leaving at the top of the structure.This phenomenom, which acts much like achimney, is referred to as the stack effect.

If the HVAC system pressurizes the building,which is common in many systems. it canprevent radon entry as long as the fan isrunning. However, school HVAC systems arenormally set back or turned off during eveningsand weekends, and even if the HVAC systempressurizes the school during operation, indoorradon levels may build up during setbackperiods. Once the HVAC system is turned backon, it may take several hours for radon levels tobe adequately reduced. Adjustment of thesetback timing may, in some cases, achieveaccepts le indoor radon levels during periods ofoccupancy. Measurements with continuousradon monitoring equipment in each classroomwith elevated radon levels are necessary todetermine the appropriate setback configurationin such situations.

2.1.2 Radon Entry Rout

Typical radon entry routes include cracks in theslabs and walls, fir dwell joints, porousconcrete block walls, open sump pits, andopenings around utility penetrations. Radonaccumulated in crawl spaces may also enter abuilding. In addition, many schools have other

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radon entry points such as slab pour joints(control joints) and subslab utility tunnels.These are discussed in more detail in Section4.3, Location of Udlitt Ling.

In houses, radon problems caused by radonemanations from building materials or by radonreleased from radon.comaminated water(normally well water) occur in !solacedinstances. We would expect few schools tohave this type of radon problem.

2.2 RADON VARIATIONS WITHINSCHOOLS

Experience has shown that there can be largedifferences between radon levels in classroomson the same floor. Causes for theseroom -to -room differences are thought to includevariations in the soil under the class rooms.variations in the construction between rooms,variations in the number and size of cracks indifferent rooms, and variations in the design andoperation of the HVAC system. Thisroom- to-room variability makes it difficult todetect and mitigate all the rooms with highradon levels unless every classroom on or belowground is tested.

2.3 MITIGATION TECHNIQUES

Although the selection of the most appropriateradon mitigation technique depends on theunique characteristics of each building, fivemitigation approaches have been common inhouse mitigation, either alone or incombination. These include: subslabdepressurization (SSD), submembranedepressurization (SMD) in crawl specs areas,sealing, pram:haiku, and natural andmechanical ventilation. (For additional detailson these and other mitigation techniques forhouses, refer to the technical manuals previouslyreferenced.)

These techniques and their applicability toschools are briefly discussed below. Becausecurrent radon mitigation experience in schools islargely limited to SSD, this guidance documentfocuses on that approach. Where available,

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guidance for other techniques is also given.The reader should review Sections 5 and 6 formore detail.

EPA feels that many of the radon reductionapproaches for houses will be applicable toschool mitigation, and research is in progress toconduct additional testing of these techniques inschool buildings. It should be understood thatin many types of schools there is little or noexperience in radon mitigation. Examples ofschools that may be difficult to mitigate include:schools with poor ...bslab permeability(explained under SSD); schools with subslabductworks; schools with exhaust fans to increasefresh -air infiltration (potentially causing largenegative pressures and increased radon entry);and schools constructed over crawl spaces.

2.3.1 Subslab Depressurization ISSD1

SSD has been the most successful and widelyused radon reduction technique in slab-on-gradeaid basement houses. Installation of an SSDsystem involves inserting pipes through theconcrete slab to Emu the crushed rock or soilbeneath. A fan is then used to suckradon-containing soil gas from under the slabthrough the pipes, 'teasing it outdoors. SSDworks by emetics a negative pressure fieldunder the slab relative to the building interior;this interior/exterior pressure relationshipprevents radon-oantaining soil gas from enteringthe building.

The material under the foundation slab must bepermeable enough to allow air movement underthe slab so that adequate suction can be inducedacross the entire slab. (Subslab permeability orair flow is often referred to as subslab"communication' or 'pressure field extension.")When subslab pressure field extension isinadequate, additional suction pipes may be ableto increase the area that can be depressurized.

Initial results indicate that SSD can successfullyreduce radon levels in some schools by over 90percent if crushed aggregate or other permeablematerial is under the slab to allow for adequatepressure field extension. However, schools withpoor subtle communication and those usingreturn-air ductwork beneath the slab may

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require an alternative mitigation approach toSSD.

2.3.2 iMillinkailLainginallililLiallalA variation of SSD, often referred to assubmembrane depressurization (SMD), has beenvery successful in redudng radon levels inhouses constructed over crawl spaces. Apolyethylene or rubber membrane is laid overthe earth floor and sealed to the crawl spacewalls and internal piers. Suction is applied tothe soil underneath the membrane and the soilgas is exhausted to the outdoors. EPA has notyet researched this method in schools; however,SMD may prove more difficult in many schoolcrawl spaces because of all the internalfoundation walls, the large areas to be treated.and the possible presence of asbestos.

2.3.3 leanThe effectiveness of sealing alone as a radonreduction technique is limited by the ability toidentify, access, and seal major radon entryroutes. Most building have so many radonentry routes that sealing only the obvious onesmay not result in a significant degree of radonreduction. Complete sealing of all radon entryroutes is often impractical. In some building,certain areas will be diflIcilt, if not impossible,to access and/or seal without significant expense.In addition, settling foundations and expandingfloor cracks continue to open new entry routesand reopen old ones. Typical initial radonreduction from extensive sealing in houses isusually about SO percent.

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2.3.4 Pressurizatign (Thumb Hypic System

A potential mitigation approach for schools isadjustment of the airhanding system tomaintain a positive pressure in the schoolrelative to the subsiab area, discouraging theinflow of radon. This technique, referred to aspressurization, has been shown to be aneffective temporary means of reducing radonlevels in some schools, depending on the designof the HVAC system. If pressurization throughthe HVAC system is under consideration as along-term radon mitigation solution in a givenschool, proper operation and maintenance ofthe system are critical. Responses to changes inenvironmental conditions and any additionalmaintenance costs and energy penaltiesassociated with the changes in operation of theHVAC system must also be carefully considered.There may also be potential moisture andcondensation problems if pressurisation isimplemented in very cold climates.

2.3.5 Inagninglallagynailima. MasaikIVAQ System Contr911

An increase in building ventilation rate, byopening lowerlevel windows, doors, and ventsOf by blowing outdoor air Into the building witha fin, reduces radon levels by diluting indoor airwith outdoor air and by minimizing the pressuredifferentials that draw radon into the building.However, EPA's preferred radon reductionstrategy has been to prevent radon entry intobuildings, rather than to reduce radon levelsonce it has entered. Experience has shown thatit is minify impractical to lower radon levels inhouses much more than SO percent throughincreased ventilation. Therefore, in mostclimates, reducing radon levels throughventilation should only be considered as atemporary measure.

3. ANALYZING THE PROBLEM

Understanding a school radon problem anddeveloping a mitigation strategy involves acareful review of all radon testing data, awalk- through audit, and a revieW of relevantbuilding documents. Applicable critical buildingcomponents (as discussed in Section 4) shouldbe examined. These Include the buildingstructure, the HVAC system, and the location ofutility lines. Special radon diagnostic tests willalso be useful These might include continuousmonitoring of radon levels during variousbuilding operating conditions, mapping ofsubslab radon, and measuring subslabcommunication and pressure field extension todetermine if SSD is applicable. Diagnostic testsare discussed in more detail in Section 5. Ageneral outline of the steps involved follows.

STEP 1: REVIEW RADON TESTRESULTS

Write down all radon test results on copies ofthe school floor plan so that rooms with highreadings can be correlated. Test data shouldinclude type of measurement device, length ofmeasurement period, HVAC operatingconditions, school occupancy, and weatherconditions during the test period. In developinga mitigation plan, emphasis should be on theconfirmatory measurements rather than thescreening measurements, as described in "RadonMeasurements in Schools An Interim Report'.(See Section 1.2, Additional Sources o(Information.)

STEP 2: WALK-THROUGH AUDIT

Thoroughly examine all parts of the building incontact with the soiL (In a basement school,examine both the basement and first floor.)Note the promos of possible radon entryroutes such as ficariwall cracb and otheropenings to the soil and determine if theycorrelate with arras having slanted radonlevels.

:, IEP 3: EVALUATE HVAC SYSTEM

Depending on the aesip and operation of theHVAC system, relatively strong indoor pressures

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(either positive or negative) can be exertedduring system operation. Where possible.obtain a complete description of the HVACsystem design and operation from the buildingfacilities personnel and determine if HVACoperation is causing any negative pressures inthe building relative to the subslab area. If theoriginal school has any additions, be sure tonote if there are different types of HVACsystems, as well as structural differences betweenthe additions. In some cases, consultation witha qualified firm experienced in HVAC systemdesign may be useful in understanding possiblesources of HVAC depressurization.

STEP 4: REVIEW BUILDING PLANS

Study the foundation plans and specificationsfor information on aggregate or gravel beneaththe slab, for the layout of footings and subslabwalls that could limit subslab communication inan SSD system. and for the presence of subslabductwork.

STEP 5: CONSULT EXPERIENCEDMITIGATORS

School personnel with little experience in radonreduction should use experienced or certifiedradon mitigation firms to pin the advantage oftheir experience and specialized knowledge oflocal problems. These firms may also be ableto provide specialized equipment such as

continuous radon monitors, core drills, andsensitive pressure gauges. Since radonmitigation in schools is a relatively new field, itis probable that mitigators in many parts of thecountry will be more experienced in mitigationof houses than schools.

Local and state health departments and EPAregional offices maintain lists of persons whohave attended EPA mitigation training courses.Several state* have initiated programs forcertification of radon mitigation companies, andseveral trade associations have been offeringmembership or educational courses forprofessionals in the field. In 1990, EPA willpublish a national list of mitigators who have

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met the requirements of the Radon ContractorProficiency Program.

STEP 6: PLAN MITIGATIONSTRATEGY

Radon mitigation is not an exact science. Inschools it is often best to przzeed In phases:install the simplest system that promises thebiggest payback and retest to determineeffectiveness; then use this information toproceed with subsequent phases, as necessary.The phased approach should be especially

helpful in schools because experience is limitedand the builelinp tend to be more complex thanhouses. Because we often do not know all theradon catty routes or forces drawing radon intothe building, the first phase of mitigation canusually provide valuable information. Thefollowing sections cover the critical buildingcomponents relative to radon entry andmitigation, the design and installation of SSDsystems, and other mitigation approaches. Thecase studies in Appendix B are examples of thephased approach to mitigation.

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4. CRITICAL SCHOOL BUILDING COMPONENTSFor help in understanding the causes of elevatedradon levels is roots and to better designschool mitigation systems, three buildingcomponents are of primary concern: thebuilding substructure(s), the design andoperation of the HVAC system(s), and thelocation of utility lines. This section discusseshow these aspects of school buildings relate tohouse mitigation experience, bow these buildingcomponents; tend to affect radon entry inschools, and how they may impact mitigationsystem design and operation.

An understanding of these critical t uildingcomponents and how they relate to a specificsituation are important when designing a schoolmitigation system.

4.1 SCHOOL SUBSTRUCTURES

The three basic substructure Types areslab-on-grade, basement, and crawl space. Themajority of substructures in the school districtsstudied thus far were slab-on-grade. Schoolsoften have one or more additions, and eachaddition may have a different type ofsubstructure.

Because of larger building and room sizes,schools often have interior footings and subslabfoundation elements. These may create subslabcomminicadon barriers between areas. Thelocation of subsist) barriers and their influenceon subslab cornmuniestigm will depend onbuilding size and configuration, and onarchitectural preferences for carrying goof load.The locations of these barriers may affect ttenumber and placement of SSD suction points ina slabonpads or besemeet structure, andfoundation plans, If available, should always bidexamined when Isistang suction point locations.This increases the opportunity for all areas withelevated radon levels to be adequately treated bythe SSD system.

4.1.1 Blab-cm-Graft

Since current research indicates that SSD is themost succeuful technique for reducing radon

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levels in slab -on -grade schools with goodsubslab communication, the constructiondocuments should be checked for informationon the type and amount of subslab gravel oraggregate. Even if aggregate is specified, theair-flow resistance of different aggregate typeshas been found to differ significantly. Subslabcommunication measurements and visualinspections are often necessary to effitientlydesign an SSD system.

Interior footings and rolled footings (gradebeams) may pose substantial barriers tocommunication between areas; therefore, it isnecessary to carefully examine the foundationplans when designing an SSD system.Depending no the type of subslab barrier andthe material underneath the barrier (e.g., clay.sand, gravel) there may be limitedcommunication, if any, across these bafflers.Often, it may be necessary to locate additionalsubslab suction points if areas to be mitigateddo not communicate across subslab barriers. Inother cases, coverage of the SSD system may beincreased if a larger fan and/or pipe diameterare used. Evaluation of subslab communication,as discussed in Section 5.7, will indicate theeffect that these subslab bafflers will have onSSD system design.

4.1.2 Basemen%

Schools with basements may present a difficultproblem because a large area is in contact withthe soil. Some school basements are completelybelow-grade and others are walk-out basements.Walk-out basements are commonly used asCiASSIVOMS or workspace. Many full basementsin older buildings have also been converted toclassroom space. Below-grade walls, the slab,and downfall cracks can be significant sourcesof radon entry. If there is adequate subslabcommunication, SSD is probably the mostdesirable approach to radon mitigation in mostbasement schools. All of the comments on SSDsystems in the above section on slab-on-gradeschools are applicable to basement schools. Inaddition, any asbestos in the basement shouldbe removed or encapsulated according to theAsbestos Hazard Emergency Response Act

(AHERA) before attempting any radonreduction activities in the basement.

4.1.3 CISELSIMEll

Most crawl space schools tend to be constructedon concrete slabs supported by periphery andinternal foundation walls, although schools withconventional wood joist and floor constructionover a crawl space and 'portable" classrooms doexist Crawl spaces are usually divided intocompartments that are all interconnected byopen passages allowing access to utility pipes.To avoid freezing of inadequately insulatedpipes, some school crawl spaces have no vents.As a result, high levels of radon may collect inthe crawl space. (Elevated levels of radon canaccumulate in a vented crawl space as well.)

Increasing natural ventilation by opening crawlspace vents may be a possible solution as longas the changes in temperature do not causeproblems such so freezing pipes, condensation,or cold floors. Whether this will adequatelyreduce radon levels will be school specific.Depressurization of the crawl space has beenmore effective in reducing radon levels inhouses than natural ventilation of the crawlspace; again, experience in schools has beenlimited. Submembrane depressurization (SMD)has also been successful in reducing radon levelsin houses built on crawl spaces. However, SMDhas not yet been researched by EPA in anyschools. It is possible that the application ofthis technique may be difficult in many schoolsbecause of the large area to be treated andcomplicating interior crawl space walls.

More detailed guidance on these approaches forschools will be available following furtherresearch. In any cue, any asbestos in the crawlspace area should be removed or encapsulatedaccording to AHERA before attempting anyradon reduction activities in the crawl space.

4.2 HEATING, VENTILATING, ANDAIR-CONDMONING (HVAC)SYSTEMS

Understanding the school's HVAC system oftenplays an important role in determining the

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source of, and the solution to, the radonproblem. American Society of Heating.Refrigemtirg and Air-Conditioning Engineers(ASHRAE) Standard 62.1981R 'Ventilation forAmeptable Indoor Air Quality'' should beconsulted to determine if the installed HVACsystem is designed and operated to achieverecommended minimum ventilation standardsfor indoor air quality. Sometimes schools andsimilar buildings were not designed withadequate ventilation, and in other instances,ventilation systems are not operated properlydue to factors such as increased energy costs oruncomfortable conditions caused by a design ormaintenance problem. It is advisable to achievethe recommended minimum ventilationstandards in a school in conjunction with or inaddition to installation of a system for radonreduction. Consultation with a qualified HVACfirm or a registered Professional Engineerexperienced in HVAC system design isrecommended for evaluating the HVAC systemboth in terms of radon mitigation options andindoor air quality.

HVAC systems in the school districts initiallyresearched by EPA include: central air-handlingsystems, room-sized unit ventilators, and radiantheat. Unit ventilator and radiant heat can existwith or without a separate ventilation system.Central air-handling systems and unit ventilatorstend to be most prevalent in newer schools,particularly if air-conditioned. Often, because ofadditions, schools may have more than one typeof HVAC. system.

4.2.1 Central-Air Handling Systems,

In many buildings with air-conditioning, theHVAC system contains some type of centralair-handling system. The systems can varywidely in size and configuration, and thedifferent types of systems will tend to haveunique effects on radon entry and subsequentmitigation. Three types of central air-handlingsystems common in schools are summarizedbelow: single-tan systems, dual-fan systems, andexhaust-only systems.

In lingie-face systems the air is distributed to therooms (normally under pressure) by theair-handling but, and the return air is brought

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back by the same fan. These systems are similarto forced-air systems in houses, except that freshair can usually be mixed with the return air.The air-handling faces may operate continuouslyduring the day, or they may operate only whenheated or cooled air is required, cycling on andoff throughout the day with thermostat controLIn any case, the systems are normally set backor turned off during evening' and weekends.These single-fan systems are normally designedto generate neutral or positive pressures in allrooms. In a single-fan system, stale air leavesthe building either through a separate exhaustsystem. by relief, or by adUtration throughcracks and openings due to overpressurizationby the fan (if fresh air is brought into thesystem).

Larger air-handling systems often employ adual-fan system: an air-disuibution fan and asmaller return-sir fan. The return -air fan allowsfor forced exhaust of return air. Louversregulate the amount of fresh air brought intothe air supply and the amount of return air thatis exhausted. Dual -fan systems are usuallydesigned so that they generate positive pressuresin all rooms when operating; however, if thereturn-air fan pulls more air from a room thanthe supply fan is furnishing, then the room canbe run under negative pressure causing soil gasto enter the room through openings to the soilbeneath the slab. The fans usually operatecontinuously during the day and are either setback or turned off during evenings andweekends.

Although single- and dual-fan systems arecommonly designed to operate at positive orneutral pressures, pressure measurements inschools have indicated that such systems cancause signifkant myths pressures in thebuilding. HVAC einem modifications (such asreducing the amount of freelt4ir intake), lack ofmaintenance (such Is dirty filters), unrepaireddamage, or other boon Can falla lasubstantial asthma pressures in some rooms,thus increasing soil ps entry.

The third type of central air-handling system isan exhaust-only rates in which no supply air isprovided mechanically. Such systems aregenerally used for ventilation in schools that

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heat with radiant systems or unit ventilators andhave no central air-handlers. The fans exhaustair through a central ceiling plenum above therooms or with roof mounted exhausts in many

These systems are designed to drawfresh air into the rooms by infiltration throughabove grade cracks and openings; however,radon can enter through below grade cracks andopenings. The fans in exhaust-only systemsusually are normally off at night but mayoperate continuously during the day. This cangenerate a negative pressure in all rooms and,consequently, Increase the potential for radonentry.

4.2.2 Unit Ventilatom

These self-contained units provide heatingand/or air-conditioning in individual rooms.They are usually installed on outside walls withan enclosure which contains finned radiatorsand/or coils. They can also be located overheadin each room and are sometimes above thedrop ceiling. Unit ventilators normally containone or more farm and a vent to the outdoors sothat fresh air can be pulled in by the fan(s).An adjustable damper allows a variation in themix of recycled room air arid fresh air fed tothe circulating fan. Fresh-air intake can beminimal because of obstruction of the outdoorvents due to poor maintenance or energyconservation practices. (Units that do notprovide any outdoor air by design are referredto as tan coil units, not unit ventilators.)

In some eases there is a central-buildingexhaust-fan system in schools with unitventilators, as discussed above. This exhaust fanis intended to provide ventilation by pulling airin through the unit ventilators (if their fresh-airvents are open), but it also creates a significantnegative pressure in the room. This negativepressure can pull radon into the rooms with thesoil gas. If &ed.& intakes in the unitventilators are blocked for any reason. operationof exhaust-only fans will increase the negativepressure in the building relative to the subslabVOL

Radon mitigation strategies in schools with unitventilators might include (1) opening thefresh-air vents to improve ventilation and

running the unit ventilator fans continuously topressurize the room, (2) replacing anexhaust-only vendladon systens with a systemthat operates under a slig1.6 vositive pressure, or(3) installation Of an SSD system that couldoverpower all negative pressures in the building.If the current HVAC system is providingadequate ventilation to the building or ifoptions (1) and (2) are not feasible, option (3),SSD, would be the most practical strategy ifthere is good subslab communication.

4.2.3 Radio' Heat System

Radiant heat systems in schools tend to be ofthree types: hot water radiators, baseboardheaters, or warm WSWr radiant heat within theslab. Schools heated with radiant systemsshould have a ventilation system to achieve thefresh air requirements recommended byASHRAE; however, many of these schoolsprovide no ventilation other than infiltration.In other schools. there are exhaust ventilatorson the roof. These can be passive, allowingsome ventilation through the stack effect, orthey an be powered Powered RoofVentilators (PRVs) on cause significantbuilding depruutization, particularly if a freshair supply is not provided. This can causeconsiderable radon entry into the building whilesuch exhaust systems are operating.

If SSD is under consideration as a mitigationoption in a school with intraslab radiant heat,the building plans should be carefully studied toavoid damaging any piping when placing theSSD points. An infrared sunning device can beused to help locate the cut position of subslabpipes. Satisfactory locations for SSD pipes maybe very limited in such schools.

4.3 LOCATION OF UTILITY LINES

The location of entry points for utility lines canhave a significant influence on radon entry in

schools since they can provide an entry routefrom the soil into the indoor air. Utility linelocations depend on many factors such assubstructure type, HVAC system, andarchitectural needs or practices. Utility lineslocated above grade should not cause significantradon entry problems.

In slab-on-grade and crawl spa schools, theutility penetrations from the subslab or crawlspace area to individual rooms aye frequentlynot completely sealed, leaving openings betweenthe soil and the building interior. For example.there is a potential for radon entry aroundplumbing penetrations and electrical conduits.

If utility lines, such as electrical conduits andwater and sewer pipes, are located under theslab, their exact locations should be carefullynoted from the plans, and caution should betaken when drilling holes through the slabduring diagnostic measurements. This isdiscussed in more detail in Section 5.

In some slab-on-grade schools, the utility linesare located in a subsists utility tunnel that tendsto follow the building perimeter or central hall.Utility tunnels often have many openings to thesoil beneath the slab-on-grade and,consequently, can ba a potential radon entryroute. In addition, risers to the unit ventilatorsfrequently pass through unsealed penetrations inthe floor so that soil gas in the utility tunnelon readily enter the roma If the surroundingsoil has elevated radon levels, a utility tunnelcould be a major radon catty route in schools.

It is possible that the utility tunnel could beused as a radon collection chamber for an SSDsystem, and this approach will be studied. Anyasbestos in the utility tunnel should be removedOf encapsulated according to AHERA beforeattempting any radon reduction activities in thetunnel.

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S. DESIGN AND INSTALLATION OF SUBSLAB DEPRESSURIZATION (SSD) SYSTEMS5.1 APPLICATION

Experience has shown that SSD is the mostsuccessful radon reduction technique in housesthat have aggregate or permeable soil beneaththe slab. There is much less experience withSW in schools; however, the results to date,although limited. have been promising inschools that have aggregate or clean, coarsegravel under the slab. Current guidance onradon reduction in schools is tucused ondesigning and installing SSD systems, sinceexperience in mitigating schools using othertechniques (Section 6) is very limited.

Experience to date has identified certain typesof schools where SSD may not be applicable.These include:

Schools that do not have crushedaggregate, coarse gravel, or permeablesoil underneath the slab. (Experiencchas shown that SSD systems performbest when the subslab material isapproximately 3/4 to 1414 inches indiameter, with few fines.) An SSDsystem may work in other situations ifenough suction points are installed tocreate a sufficient pressure field.However, in other cases an alternativemitigation approach will be necessary.

Schools with subslab ductwork Inhouse mitigation, the subslab ductworkis sometimes sealed off and replacedwith new aboveslab ductwork. Thiscould be difficult and expensive in manyschools, and impossible in others.

Schools with crawl space construction.Depending on crawl specs site andconflpiadon, increased crawl spaceventilation, crawl spiel depreaurizadon,Of subsembrane depressurisstion(SMD) may be applicable provided noasbestos is present.

Future school mitigation studies will researchradon reduction strategies for mitigating thesetypes of schools, and technical guidance will be

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published as soon as possible. If diagnostic testresults or other reasons indicate that an SSDsystem is not appropriate for a given school orif an SSD system can not be installed as soon asdesired, refer to Section 6, Other AQoroaches toRadon Reduction.

5.2 DIAGNOSTIC TESTING

Diagnostic measurements will help to betterunderstand the nature of the radon problem sothat an effective mitigation strategy can bedeveloped. Aggregate inspection and subslabcommunication testing are the simplest, leastexpensive, and most important diagnostics todetermine the applicability of an SSD system.Other diagnostics require more expensiveequipment and may be more difficult tointerpret, but they also may be required tounderstand the complex radon problemsassociated with larger buildings and HVACsystem operation. Diagnostics that have provenuseful in school mitigation are described below.

5.2.1 Evaluation of the rooting Structure

It is important to determine the types andlocations of potential subslab barriers, such asfootings, subslab walls, and grade beams andhow they may impact subslab communicationand mitigation system design. The presence ofbuilding walls does not necessarily indicate theposition of a footing or grade beam because notall walls are load-bearing. The building plans(foundation drawings) are the best source ofinformation on the location of footings. Notethat thickened areas of the slab (called "gradebeams") are sometimes found in schools tosupport a block wall. Their effect on subslabcommunication will depend on the depth ofaggregate or gravel under them.

Experience to date has shown that, in somecases, subslab communication will reach acrossthese barriers. However, in many cases, areassurrounded by footings, subslab walls, or gradebeams may each need at least one suction point.(This is why the subslab communication test,

which follows, is important in confirming thepresence. atent, and effects of subslab barrieis.)

5.2.2 Evaluation of Subslap communicatioa

The most important parameter in assessing theapplicability of SSD is subslab communicationr pressure field extension. PermeableAgregate, screened, coarse, and approximately3/4 to 1.1/4 inches In diameter, is preferable.Building plans and specifications have beenfound to be generally accurate in determiningthe presence of aggregate, but the aggregatequality must be determined by inspection. Ifaggregate is not mentioned in the specifications.it may not be present even though it is shownon the foundation drawings.

Subslab communication can be evaluated byusing a shoptype vacuum for suction at onelarger hole (normally located at the potentialSSD point) and pressure sensors at othersmaller holes. The suction hole should be atleast 1inch in diameter or larger. and the testholes should be approximately 318.inch indiameter and should be located at variousdistances and in various directions from thesuction hole, depending on building size andconfiguration. This approach will indicate thefeasibility of developing a pressure field undervarious parts of the slab and will also help toidentify the influence of subsists barriers such asgrade beams or below grade foundation walls.It will also help to indicate competing pressuresor excessive leakage from subslab ductworkwhich would inhibit pressure field developmentin an SSD system.

Experience has shown that the size of the areathat can be mitigated by each SSD point variesfrom a few hundred to several thousand squarefeet. The coverage will be dependent onsubslab communication, the flow capacity of thefan and pipe, the prensece of subsiab barriers,and on the Ur sa. of the building pressuresand leakage that the system must overcome. Ofcourse, if subslab permaebility is limited, thenthe pressure field may at ad only a few feetand many SSD points may be necessary toadequately treat the entire area.

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Pressures at the primary (1inch plus) suctionpoint are typically measured at suctions of about8, 6, 4, 2, and 0 inches WC. The pressures atthe test hole can be measured eitherqualitatively (with a smoke stick) orquantitatively (with a pressure gauge). Ifcommunication testing indicates a pressure of0.001 inch WC (0.25 Pascal) or lower at a giventest hole or if smoke stick rests show that airflows into the hole, it may be possible that anSSD system will be able to reach the area.

This procedure requires an electricpneumatichammer drill, a vacuum, and a sensitive pressurest.iaor. actor' drilling into th utilitypipes and conduits should ix no.ed from theplans and confirmed to avoid drilling throughthem. Refer to Section 7.2 on workerprotection for safety suggestions.

AggregAte quality can also be inspected bydrilling at least one hole in the slab, largeenough (at least 4- inches in diameter) to extracta sample. Holes larger than 4.inches will allowfor a better estimate of the depth and porosityof aggregate, but holes of this size may alsocause more damage to floor tiles and be moredifficult to repair. Again, proper precautionsshould be taken when drilling through the slab.Although this approach will indicate thepresence of subslab aggregate and the potentialfor subslab communication, it will not indicatethe anent of pressure field development that ispossible with the communication test.

5.2.3 evaluation of Pressure Differentials

If the radon tests were made with the HVACsystem or other ventilation fans on, it may beuseful to retest the rooms (at least the ones inquestion) with all fans turned off in order toisolate the major sources of radon and todetermine if HVAC operation is influencingradon levels. Changes in radon levels due toHVAC operation may indicate the significanceof the pressures (both positive and negative)generated by HVAC operation and the potentialfor mitigation by HVAC modifications (SeeSections 4.2 and 6). Pressure differendals andair flow measurements in classrooms can beused to identify any HVAC flow imbalances thatmay cause negative pressures in the building

relative to the subalab area. Thesemeasurements require sensitive pressure gaugesand/or air flow meters. Qualitative informationcan be obtained by using a smoke stick toindicate the direction of air flow.

If the HVAC system pressurizes the building, itcan prevent soil gas entry as long as theair - circulating fan is running. However,installation of an SSD system may still benecessary if radon levels build up tounacceptable levels inside the school when thefans are off and it takes too long to reduce theradon to acceptable levels when the system isturned back on.

If HVAC system operation or the natural stackeffect exerts a negative pressure in the buildingrelative to the subsiab area, then a successfulSSD system must overcome this negativepressure. Recent experience with SSD in alimited number of schools indicates that awell-constructed SSD system can provideconsiderable reductions in radon despite strongHVAC counter pressures. However, it may bedifficult for an SSD system to overcome thenegative pressures exerted by return-air ductslocated under the slab.

Continuous radon measurements (typicallyaveraged over 1hour intervals) collected forseveral days will show variations in radon levels.These variations can result from changes inHVAC operation, diurnal effects, weatherconditions, and occupancy patterns. These datamay lead to a greater understanding of thepressure dynamics in the building however, arelatively expensive continuous radon monitor isrequired. Continuous differential pressuremeasurements (inside/outdOottsubslab) collectedconcurrently with the continuous radonmet- laments, are also extremely useful inunderstanding HVAC system influence on radonentry.

5.2.4 hillia12111111.1111111111111.111ilaliedi

Subs lab radon monuments are used to mapradon source strengths so that the suctionpoint(s) can be placed near the major sources.The subslab radon measurements can becollected through the 1/4 -inch diameter holes

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drilled into the slab in the subslabcommunication test detailed above. To obtainthe most representative results, the substabradon levels should be measured prior to thecommunication test. This diagnostic techniquerequires a hammer drill and a continuous orgrab radon monitor that can pump air samplesinto a measuring chamber. Defore drilling intothe slab, utility pipes and conduits should benoted from the plans and confirmed to avoiddrilling through them.

5.3 DESIGN AND INSTALLATION

Installation of SSD systems is primarily a matterof plumbing because of the extensive use ofPVC pipe. Electrical work, concrete work, androof work are often also involved. Due to thenature of the work, it is important that theinstaller take into account all applicable codesthat may affect construction and/ormodifications to school building ;. Typically,these may include electrical, mechanical, fireprotection, plumbing, and building codes(Section 7).

A typical SSD system for a school is shown inFigure 1 and should be referred to throughoutthe section.

5.3.1 Suction Hole Locatioe

The location of the suction hole is selected oncean area or room to be treated has beenidentified based on radon measurements, subslabcommunication tests, and any other diagnosticmeasurements. For optimum mitigation itwould be best to locate the suction hole closestto the highest !mown radon source. Of course,if the moms with higher radon levels are widelyseparated, then they are probably independentand must be treated separately. Often, thesource may be widespread or unidentified or thesuction bole may need to be located in anout-of-the-way place that will cause minimumdisruption to the room occupants.

Another consideration when locating suctionpoints is the accessibility of the exhaust pipeand exhaust kn. In many cases the suction holeposition is chosen on the basis of aesthetics, fan

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22

location, or exhaust pipe routing. Often alocation equidistant from both outside walls,such as a hall or a closet on the hall side of aclassroom, is a good location if subslabcommunication h sufficient.

5.3.2 pipe and_ Fan Layout

In order to adequately depressurize school slabs.which may be much larger than house slabslarger fans and larger pipes to carry theincreased air flows are typically used. AppendixA contains information on fan and pipeselection which lists a number of fans with thecapability of drawing over 300 cubic feet perminute (dm) at 314-inch WC (which may bethree to four times the capacity of homemitigation fans).

The typical 4-inch pipe used in most homemitigation systems may have too much flowresistance when used with this larger fan;therefore, 6-inch pipe is often used. Thepiping used should be Are -rated (minimumSchedule 40 PVC).

If the permeability of the aggregate is high, thena single 6-inch suction point can be used withthe larger pipe and fan. However, with typicalaggregate permeability, a wider area can bemitigated by using two or three suction pointsmanifolded to one of the more powerful fans.The location for the SSD point(s) should beselected based on the results of the diagnosticmeasurements. A typical manifold system mightconsist of a 6-inch PVC pipe runninghorizontally within a dropped ceiling andextending 20- to 60-feet between vertical drops.Connected to the manifold would be an exteriormounted fan, and 4-indt PVC vertical pipeswhich penetrate the slab and transmit vacuumto that area of the door slab. This arrangementcan be used to Wiliam a long classroom wingwith the suction points located in the centralcorridor or on the corridor side of a classroom.Experience in schools has shown that locatingthe suction points remote from the outside wallwill help to reduce short circuiting (satisfyingfan demand for air) of the system.

If any of the pipe is either outside the buildingor in an unheated section of the building, then

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condensation may form inside the pipe becauseof the high moisture content of the exhaustedsubslab soil gas. The pipes should always beslanted so that this condensation can drain backinto the subslab cavity where it originated.(The in-line fans should be mounted verticallyto prevent water ac nimulation in thebeihaped housings.) Experience has shownthat SSD systems in homes can fail due to abuildup of condensation in improperly orientedfans and pipes. In humid climates, condensationwill also form on the outside of pipes inexposed areas, and insulation or boxing in maybe necessary. Rain entry into uncapped exhaustpipes has not been reported as a problem.probably because the volume of rain is smallcompared to the volume of condensation that iscontinually flowing back down the exhaust pipes.Ice buildup on the fan or on the exhaust stackhas not been reported as a significant problem.probably because the soil gas is warm enough tomelt any ice or to prevent it from forming.

5.3.3 Suction Point gnsl ape Installation

Once the location of a suction point isdetermined, a hole must be drilled through theconcrete slab. Typically, the slab hole diametercorresponds to the pipe's outside diameter.malty slightly larger than 4- to 6-inches. Thehole must be large enough to accommodate thesuction pipe and to allow the excavation of acavity beneath the slab. before drilling into the

utility pipes and conduits should be notedfrom the plans and confirmed to avoid drillingthrough them. Recommended concrete drilltypes are discussed in Appendix A.Alternatively, core drilling companies can behired to drill this type of hole. If a schooldistrict anticipates mitigating a large number ofschoob using SSD, they should considerpurchasing a drill. Worker protection shouldinclude respirators and eye protection, inaddition to ventilation of the work area todilute radon that is released by opening up thesubslab.

An open hole or cavity, as seen in Figure 1,should be excavated beneath the slab with adiameter of approximately 3feet and a depth ofabout 1-foot. Experience has shown that when1-foot diameter cavities have been enlarged to

2- to 3-feet and the depth increased to 1 -foot.the negative pressure fields have often doubledbecause of the declassed resistance. Althoughperformance improvements have been variable,this larger cavity sin has proven mostworthwhile in nonporous soils (where the mostimprovement is sought). Aggregate cansometimes be removed from the subslab eitherby hand or with a powerful shop vacuum. Ifthe aggregate is packed tightly, a crowbar andhand excavation may be necessary. Largesubslab cavities may require opening up a largerslab hole just for aggregate removal. This holewill have to be resealed with concrete.

The exhaust pipe should be well supported sothat it will not be knocked loose if it is jostled.In school environments it is advisable to enclosethe pipe for both security and aesthetics.

5.3.4 Fan Inotallatiou

The EPA recommends that SSD fans beinstalled outside the building because of thechance of leakage of highly concentrated radonfrom the fan or the pipe exhausting from thefan into the building interior (since the fan andexhaust pipe are under positive pressure).Figure I. shows two possible fan mounts. Inhouses the fans are usually placed in attics, butin schools they have been placed on the roof oron the upper sidewall of the building exterior.(See Appendix A for a discussion of SSD faninstallation variations.) Wall penetrations areusually preferable because roof penetrations maylead to roof leaks. Several fan configurationsare possible: in-line mounts that couple topipes, pedestal mounts with a vertical discharge,and pedestal mounts with a horizontaldischarge. However, the piping configurationand fan placement must be guided by buildingcodes in addition to practical considerations.

The system should exhaust above the maim toprevent high coaceatrations of radon fromre-entering the building. A location should bechosen which provides a reasonable distancebetween the discharge point and HVACfresh.* intakes, windows, doors, or any otheropenings to the building interior.

5.3.5 avlintsg Radon Entry Lutes

To enhance the performance of the SSD system.an effort should be made to seal as many radonentry routes as possible. This increases thestrength and extent of the negative pressurefield and also reduces the amount of treatedindoor air that will be drawn into the SSDsystem. Entry routes that should be sealedinclude cracks in the slab and walls, thefloor/waU joint, the surface of porous concreteblock Ina, and openings around utilitypenetrations. Fibrous expansion johns, that arecommonly used when the slabs are poured. canalso serve as radon entry routes. These and allother cracks and porous surfaces Mould beproperly prepared and sealed with a suitablesealant.

53-6 ililidliSfilliPtirl

Troubleshooting SST. 10.41IntiS may involvetaking a number of dtnenntic measurements. Ifradon levels are not adec,aady reduced, thesuction in the subslab cavity should bemeasured. Low pressure may indicate high airflow or poor fan performance; high pressureindicates poor subslab permeability or low airflow. The air flow in the pipe may have to bemeasured to determine whether the fan isoperating properly. The pressure field extensioncan be measured at various distances from thesuction hole(s) to determine the coverage of theSSD system.

5.3.7 Improving_ System Performance.

Some causes of insufficient subslab pressurefield development include: poor subslabpermeability, the presence of subslab barriers,competing pressures from cubslab return-airductwork, and sir leaks into the system (eitherair - supply ductwork or from cracks oropenings). If the performance of an SSDsystem is not adequate, a number of differentsteps can be attempted to improve systemeffectiveness. These include:

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Additional suction points can beinstalled to increase coverage area.(This approach is mat suitable when

common cation is poor or pressure andflow are low.)

Larger pipe diameter:, larger fans, andlarger subelab cavities have been shownto improve SSD system performance insome cases. (A larger fan and pipediameter are most appropriate when thepressure is low and the flow is high.)

Sealing of cracks and holes can alsoimprove the negative pressure fieldextension and, consequently, radonreduction. Sealing will also help toreduce the enemy penalty associatedwith the in -teased exhaust of indoor airinto the S.SL system.

Reductions in room depressurization (ifapplicable) may also improve radonmitigation.

Finally, it is possible that the suctionpoint has been located in a spot withsuch poor permeability that majorimprovements can only be made byabandoning the current hole and drillinga new hole in an area with betterpermeability.

5.3.8 System Maintenance and Monitoring

One of the chief advantages of SSD systems isthat there is relatively little maintenance

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required for their operation. and the fans havelong lives. Periodic system inspection andannual retesting of the radon levels may besufficient if fans with an expected service life of10-20 years are installed.

The SSD system pressure levels could bechecked and all measurements recordedroutinely, as is done with the inspection of fireextinguishers. A pressure gauge is the mostcommon type of monitoring device that is usedto evaluate the continued performance of a SSDsystem. Typically a dial pressure gauge (about$50) is used to monitor the subslab cavity orsuction pipe pressure. The gauge is usuallymounted on or near the suction pipe where itcan be checked to determine if the suctionpressure is adequate. Other devices thatcontain pressure switches to turn on a light orsound an alarm if the pressure falls below agiven value are also available and are thepreferred method.

Each SSD system should be labeled with itsinstallation date, nominal subslab cavity or pipepressure depending on monitoring system, andthe name and telephone number of the personsto contact in case of failure. Once the finalvstem is installed. p2pmitiation Won lever

should bi Mailed annggilvIdurIng, coldnargaigsagrujigLiktonaLlumplagdata

6. OTHER APPROACHES TO RADON REDUCTION

Other mitigation approaches, in addition toSSD. have been used in some schools. Theseapproaches may be implemented either as atemporary solution prior to installation of apermanent SSD system, or they be considered asthe first phase of a more extensive mitigationplan. In some cases, implementation of theseapproaches alone may adequately reduce radonlevels in the school. After confirming adequatereductions with short-term tests, follow up withlong-term measurements to ensure that thesystem continues to maintain an adequate levelof radon reduction.

Classroom pressurization, increasing ventilation,and crawl space depressurization are discussedbelow. It should be emphasized that theseapproaches have not yet been thoroughlyresearched by the EPA in school applications.and more definitive guidance will be publishedfollowing additional research. Other mitigationtechniques. such as extensive sealing andsubmembrane depressurization (SMD) in acrawl space will also require extensive testing.For technical details on how these techniqueshave been used in house mitigation, refer to themanuals on radon reduction listed in Section1.2.

6.1 CLASSROOM PRESSURIZATION

Maintaining a positive pressure in the building(relative to the subslab area) through HVACsystem operation has been used successfully fortemporary mitigation in a limited number ofschools. Whether pressurization is a feasiblelong-term mitiptioa solution depends uponfactors such as the proper operation of theHVAC system by asisteassa personnel,performance with cuffs= climatic conditions.and any additional ilidIneeence costs and energypenalties associated with the changes inoperation of the HVAC system. Any HVACmodifications should be made in cooperationwith a qualified HVAC system specialist.

Since central HVAC systems are normallydesigned to operate in a forced supply mode,the occupied spaces may be maintained under a

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slight positive pressure (relative to theoutdoors) deputing on the balance betweenthe supply and the exhaust in the building.These cysts= should be checked periodicallyfor proper operation to ensure that a positivepressure is maintained, and adjustments shouldbe made as necessary. HVAC modificationsthat reduce fresh air intake, reduce supply air.or increase return air in a given area. andimproper system maintenance can lead topressure imbalances, and, consequently increaseradon entry.

If positive pressures are not being achieved in asingle-fan system, the system should be checkedto ensure that the fresh -air intake meets designspecifications and that the intake has not beenclosed or restricted. Increasing the fresh-airintake and operating the fans for a sufficienttime prior to occupancy and continuously whilethe school is occupied will help to reduce radonlevels that accumulate during night or weekendsetback periods. This approach will maintainlow levels during occupied hours by maintaininga positive pressure to prevent radon entry andproviding fresh (dilution) air.

In dual-fan systems, the return-air fan can be setback or restricted so that all the rooms areunder a positive pressure with only the supplyfan operating. The fresh-air intake to thesupply fan can also be increased up to thedesign limit of the system. Another optionmight be to consult with a HVAC engineer toredesign a fresh-air intake or to add one to asystem. Diagnostic measurements made withcontinuous radon monitoring equipment in each,

ShilL9110L2fahAilidiallikULIELO can help todetermine the necessary fan operation schedulein such situations.

In schools with unit ventilators, increasing thefresh-air intake to the design limit andopted/4 the fans continuously while the schoolis occupied will help to maintain a positivepressure in the building. A central exhaust-onlyventilation system used in conjunction withunit ventilators or fan coil heaters might needto be modified or replaced with a system thatoperates War a slight positive pressure. For

schools with no active ventilation systems orexhaust-only fan systems, positive pressurizationwill probably require major modifications, suchas addition of a trash-air supply, as part of aHVAC strategy. For more detail on classroompressurization and how it would apply to aspecific type of HVAC system refer to Section4.2.

If these modifications to HVAC systemoperation are to be feasible long-termmitigation approaches in a given school, thenproper operation and maintenance of the systemis critical. Performance during various climaticconditions and any additional maintenance costsand energy penalties associated with the changesin operation of the HVAC system must also becarefully considered. In addition, there may bepotential moisture and condensation problems ifpressurization is implemented ii very coldclimates. The applicability of this approach willneed to be determined by qualified personnel ona caseby-cue basis. Changes made in HVACsystem design and/or operation should notreduce the ventilation rate below the minimumstandards in ASHRAE guidelines. In addition,any changes in HVAC controls should bedocumented, labeled, ants checked regularly.

6.2 INCREASING VENTILATION

Increasing ventilation by simply openingwindows, doors, or vents may be effective, butweather, security problems, the lack of operablewindows, and increased energy casts often makethis impractical as a permanent approach inmost schools. If the windows cannot be openedat night, it may be desirable to use a fan toblow fresh air into the building to lower theradon levels in the morning vitas the school isopened. Although this approach has beenshown to reduce Adores levels is some houses,its applicability 10 Kiwis has not yet beenstudied. Thereby, ventliadon should only beconsidered as a temporary approach to radonreduction until further research identifies itslimitations.

If an increase in ventilation is attempted. CraWispaces and unoccupied basements can sometimesbe sealed off from the rest of the building and

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treated separately. By treating these spacesseparately, ventilation reductions can beachieved in adjacent classrooms with smallerfresh air requirements and reduced energypenalty. However, the practicality of thisapproach in most climates will be limited due toincreased heating and/or cooling costs.

For reducing the energy costs associated with anincrease in ventilation, a heat recovery ventilator(HRV) may be cost-effective. HRVs allow freshair to be delivered indoors with reduced heatingor cooling costs (depending on season) ascompared to natural ventilation. Through aheat =hanger core, heat is transferred betweenexhaust and fresh air streams, without mixingthe two airstreams. However, for an HRV tobe a reasonable mitigation option, the savingsresulting from the reduced energy penaltyshould more than offset the initial cost of theHRV.

6.3 CRAWL SPACE DEPRESSURIZATION

In a variation of crawl space ventilation. anexhaust fan is installed in a crawl space ventand 111 other vents are closed. This is referredto as crawl space depressurization or forced airexhaust of the crawl space and can preventradon entry into the building interior bycreating a pressure barrier across the floor. Inhouses, this approach has been more effective inreducing radon levels than passive crawl spaceventilation. Experience with crawl spacedepressurization in schools is limited.

A diagnostic tan door test will indicate thesuitability of a crawl space for this mitigationtechnique. A fan-door (e.g., blower door) willmeasure the leakiness of the space and will helpto indicate the size of fan needed to adequatelydepressurize the crawl space. If radonmeasurements show that the crawl space is theprimary source of the problem, and if asbotosis not present in the crawl space, then thistechnique may be feasible for reducing indoorradon levels. More detailed guidance on thisapproach for schoo's will be available followingfurther research.

7. SPECIAL CONSIDERATIONS

7.1. BUILDING CODES

Building codes are typically written to reflectminimum design and construction techniquesthat must be adhered to by the constructionindustry. They are developed to ensure thepublic safety, health, and weibre. Buildingcodes are not only directed toward newconstruction but also apply to renovation ofexisting structures. They can be developed bythe national model code organizations or bylocal jurisdictions. In general, the model codespublished by such organizations as BuildingOfficials and Code Administrators International(BOCA), International Conference of BuildingOfficials (ICBO), and the Southern BuildingCode Congress International (SBCCI) areadopted by state or local jurisdictions or serveas the basis for locally amended building codes.

It is important that the installer take intoaccount all applicable codes and laws regardingqualifications for design and type of equipmentused when designing and installing radonmitigation systems in any building. Typically,this may include electrical, mechanical, fireprotection, plumbing, and building codes.However, since these codes can vary betweendifferent areas, the applicable codes for a givenlocality should be referred to when retrofitting aschool with a radon mitigation system. It isanticipated that specific additions oramendments to these mdes will be made in thefuture to address both retrofit of schoolbuildings for radon reduction and radonpreventative new construction.

7.2 WORKER PROTECTION

Worker protection during radon mitigationsystem installation is a legal, safety, and ethical

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consideration for all school administrators.Normal safety precautions must be observedwhen performing any type of construction orremodeling work. Exposure to radon gas andits decay products creates an additional healthrisk. Therefore, it is important to reduce thatexposure as much as possible. Specifically, thismay mean increasing ventilation in the workarea andior utilizing respirators in areas wherethe radon concentration is elevated. Attentionshould dui be given to other potential hazards.such as organic solvents in sealants and coatingsand potential biological hazards growing incrawl spaces or HVAC systems.

Before drilling into the slab, utility pipes andconduits should be noted from the plans andconfirmed to avoid drilling through them.(However, it should be mentioned that subslabplumbing and conduit are sometimes locatedwhere the installer finds i convenient and donot always conform to the plans.) Onesuggestion for avoiding an electrical shock inthis situation is to ground the case of the drill.If the tool itself is properly pounded, it willprevent the tool from becoming 'hot' andshould cause the breaker to disconnect theconduit that was hit. Shutting off the supply tothe drill will stop the drill but will not shut offthe subslab conduit that was hit unless theyhappen to be on the same breaker.

7.3 ASBESTOS

Any potential airborne asbestos fibers identifiedin a basement, crawl space, utility tunnel, boilerroom, or any other part of the school that maybe entered as pert of radon diagnostic ormitigation Mimi be removed or encapsulatedaccording to AHERA before attempting anyradon reduction activities.

REFERENCES

1. ASHRAE Draft Standard 62.1981R. Ventilation for Acceptable Indoor Air Quality. ASHRAE.Atlanta, Georgia, 1986.

2. Leovic, K. W., Craig, A. B. and Saum, D. The Influences of HVAC Design and Operation onRadon Mitigation of Existing School Buildings, presented at ASHRAE Conference IAQ 89.April 1989.

3. Leovic, K. W., Craig, A. B. and Saum, D. Characteristic of Schools With Elevated RadonLevels, In: Proceeding: The 1988 Symposium on Radon and Radon Reduction Technology,Volume 1, EPA-600/949-006a (NTIS PB 89-167430), March 1989.

4. McKelvey, W. F., Radon Remediation of Pennsylvania School Administration Building, In:Proceedings: The 1988 Symposium on Radon and Radon Reduction Technology, Volume 2.EPA-600/9-89-006b (NTIS PB 89-167498), March 1989.

5. Messing, M. and Saum, D. West Springfield Elementary School Report on Diagnostic Analysisfor Radon Remediation on The South Wing, Intl ken, Falls Church, Virginia, 1987.

6. Messing, M. and Saum, D. Worker Protection for Radon Mitiptors and Diagnosticians, In:Proceedings: The 1988 Symposium on Radon and Radon Reduction Technology, Volume 2,EPA-60019-89-006b (NTIS PB 89.167498), March 1989.

7. Saum, D. and Messing, M. Guaranteed Radon Remediation Through Simplified Diagnostics, In:Proceedings: The Radon Diagnostics Workshop, April 13.14. 1987, EPA- 600,9.89.057, June 1989.

8. Saum, D., Craig, A. B. and Leovic, K.W. Radon Reduction Systems in Schools, In: Proceedings:The 1988 Symposium on Radon and Radon Reduction in Technology, Volume 1, EPA- 600/9 -89-006a (NTIS PD 89.i67480), March 1989.

9. Witter (Leovic), K., Craig, A. B. and Saum, D. New-Construction Techniques and HVACOverpressurization for Radon Reduction in Schools, Proceedings of the ASHRAE ConferenceIAQ 88, 1988.

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I

INV

APPENDIX A: TECHNICAL INFORMATION

A.1 USING CONSTRUCTIONDOCUMENTS

The term 'construction documents' refers to theformally agreed upon construction drawings andspecifications (project manual), as well as allsubsequent addenda and change orders. Thedocuments are a complete pictorial depiction ofthe project and consist of the architectural,structural, mechanical, and electrical drawings.The specifications include the biddingdocuments, the conditions of the contract, andthe technical information that outlines materialsand workmanship for the entire project.

Both the specifications manual and the drawingsshould be obtained to aid in the understandingof the building's radon problem. Each of thesewill provide useful information. Table Alsummarizes the information provided in thesedocuments.

Document

A.1.1 Specifications,

The specifications will primarily aid themitigator in identifying subslab aggregatecomposition and soil compaction requirements.Both of these are usually found in the sectiondetailing concrete work and/or fill (typicallyDivision 3 Concrete). The mechanical section(Division 15) summarizes the heating,ventilating, and air-conditioning (HVAC)systems applicable to the building. This sectionwill give details on the mechanical equipmentand offer design information that may or maynot be found on the drawings. The electricalsection (Division 16) summarizes the electricalsystem.

Note: The specifications haveprecedence over the drawings if thereare contradictions. For instance, it isunlikely that aggregate was provided if

Table Al Radon Mitigation Information In Construction Documents

Information

Specifications:Concrete (Division 3)

Mechanical (Division 15)

Electrical (Division 16)

Drawings:Azchitecttual

Structural

Mechanical

lectrical

Subs lab composition;

HVAC system summary

Electrical system s

aggregate identification

equipment identification

=nary: equipment identification

'Typical wall sections

Foundation plan; footing locations and communicationhurlers, subslab All and material thicknessHVAC system design; including duct system design, duct runlength; supply/return flow design:, fresh-air introduction;exhaust systemsElectrical equipment design and location; conduit location

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the specifications do not call for it, evenif the drawinp show aggregate underthe slab.

A.I.2 Drawing

The drawinp provide a wealth of informationthat may be useful for radon mitigation. Thearchitectural drawinp usually show a typicalwall section. Subs lab fill Information is usuallyshown and labeled on this section. Thestructural drawinp include a foundation planwhich locates footings of load-bearing walls andcolumns. This is useful when identifyingpotential barriers to subslab. The mechanicaldrawinp should include all plumbing andHVAC drawinp. Supply and return duct runsshow the amount of supply and return air flowserving a room or area. By simply addingtogether all of the flows, it can be determined ifthe room was designed to be under positive ornegative pressure. Most sophisticated HVACsystems are designed to be balanced orpressurized in most, if not all, rooms. Thedrawinp should note whether or not fresh air isintroduced into the mechanical system and ifroom air is removed by exhaust fans.

The electrical drawings should be consulted toensure that no unusual conduit routes (e.g.,under the slab) are present in areas where theslab may be drilled (either for placement ofsuction points or for communication testing).

A.2 FAN AND PIPE SELECTION

SSD systems in houses and schools require fansthat are quiet, long-lived, energy efficient,resistant to moisture, and that have good airflow at pressures around 1 inch WC A numberof centrifugal duct fans manufactured by variouscompanies have the performance characteristicsrequired for mom radon mitigation with anexpected service Ws of 10 to 20 years. Fansthat utilize the vammial fan blade whichsurrounds the MOW can be mounted in avariety of enclosures. Specifications of sometypical in-line and pedestal fans used in radonmitigation are shown in Table A.2.

The In-line fans are designed to be mountedbetween two sections of pipe. The fan and pipe

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are usually coupled with the black rubber pipecouplings fined with stainless steel hose clampsthat are used for plumbing pipe connections.These coupling are available in a wide varietyof sizes so that pipes and fans of various sizescan be coupled. Pedestal fans are designed to bemounted on a square base that can beconstructed of pressure-treated wood. This baseis attached over a pipe penetration on a roof ora wall, and the fan is screwed onto and seatedto the base.

In houses, mitigatory often attempt to install thesmallest, quietest, least obtrusive, lowest powerSSD system possible. Pipes are generally 4inches in diameter or smaller, fans are ratedgenerally less than 100 watts power consumptionand move less than 150 cfm air at 0.75-inch WCpressure. In schools, however, theconsiderations of noise, energy loss, and size arenot as important. Larger fans and pipes shouldbe considered If they produce simpler and moreeffective mitigation. It Is recommended thatfire -rated PVC piping, Schedule 40 PVC as aminimum, be used.

Mitigation experience in schools, althoughlimited, has shown that it is advisable to usefans that are at least twice as large (200 W and300 cfm at 1 -inch WC pressure) and pipes thatare 6-inches in diameter. The higher air flowrequires larger pipe diameters so that theincreased fan capacity is not lost in piperesistance. For example, these larger pipes canbe used to provide s low restriction manifold tothe fan that is connected to two vertical 4-inchpipes penetrating the slab. The 6-inch pipe cancatty 300 cfm to the fan while each of the two4-inch pipes carries about ISO cfm. If the largerfans are attached directly to 4-inch pipes. then alarge part of the increased fan performance willbe loss to flow resistance of the pipe. Insummary, the larger slab areas found in schoolsnormally require larger fans and pipes for themost effective SSD installations.

Table A.3 shows the flow resistante for 100-feetof pipe with diameters from 2- to 6-inches. Thelength of pipe that would produce theequivalent resistance of a system that containspipe, pipe fittings, and subslab flow resistance isassumed to be about 100-feet, although typical

Fan'Type

Table Al

ElecPower(W)

'Typical Fans Used for Radon Mitigation

Noise Flow' Press. Max WidthLevel (chit) @No Flow Max.(songs) (in. WC) (in.)

PipeDiem.(in.)

PipeLength(In.)

In-line 40 2.1 25 0.8 8.00 4.0 8.50In-line 40 2.1 45 0.7 8.00 5.0 8.60In-line 40 2.1 45 1.0 8.00 5.0 7.50In-line 90 2.8 140 1.7 11.50 6.0 9.05In-line 80 2.8 140 2.0 11.50 6.0 7.50In-line 110 3.2 180 2.0 13.25 8.0 8.25In-line 110 3.2 180 2.0 13.25 8.0 9.37In-line 160 4.5 310 2.0 13.25 8.0 9.37In-line 160 4.5 310 2.0 13.25 8.0 8.25In-line 200 4.5 456 2.0 16.00 12.0 12.60In-line 280 5.6 470 2.0 16.00 12.5 10.25In-line 250 5.6 470 2.5 13.25 10.0 9.64Pedestal 90 2.7 75 0.7 na us 11111

Pedestal 90 na 90 1.4 12.50 na 8.00Pedestal 90 na 110 1.4 14.00 na 10.00Pedestal 120 na 200 1.6 16.00 na 12.50Pedestal 150 na 200 2.4 12.S) na 8.00Pedestal 150 na 300 2.8 16.00 na 12.50Pedestal 175 na 530 1.5 16.50 na 13.00

flow measured at 0.75 inch WC pressureINFILTEC measured value

Table A.3 Air Flow Resistance in 100 Feet of Round Pipe

Flow(cfm)

2-in. Pips(in. WC)

3 in. Pipe(in. WC)

4 in. Pipe(in. WC)

6 in. Pipe(in. WC)

0.34 0.04 0.01 0.0010.72 0.08 0.02 0.0021.80 0.24 0.06 0.0076.30 (..tre 0.20 0.030

2200 2.90 0.69 0.09078.00 10.30 2.40 .0.300164.00 21.60 5.10 0.670276.00 36.40 8.60 1.100414.00 55.40 13.00 1.700

These values show the approximate cows for each pipefor which the resistance is closest to 0.75-inch WC.

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mitigation systems usually do not have pipe runsof more than 40-feet. For example, if aparticular fan dnris 310 dm at 0.75-inch WCand 100 feet of 4-inch pipe has a resistanceclose to 5.1-inches WC at a flow of 300 cfm, itwould be advisable to use 6-inch pipe to avoidwasting most of the fan power on piperesistance. However, large pipe is unnecessaryif little or no subslab air flow due to lowsubslab permeability. Pressure drops caused bybends (e.g., elbows) in the pipes should also beconsidered when designing the SSD pipingsystem.

A.3 DIAGNOSTIC MEASUREMENTTOOLS

Several types of tools are useful in gatheringdiagnostic data in schools. They include anelectricpneumatic hammer drill, a large shopvacuum, a continuous or grab-sample radonmonitor, a sensitive pressure measurementdevice, an air-flow indicator, and an air-flowmeter.

Depending on the number of schools to bemitigated in a given district, it may becost-effective to purchase some of thisequipment or it may be more practical toemploy the services of an experienced radonmitigator. It may be possible to purchase someof this equipment from experienced mitigatorin the area or they may be able to recommend alocal source for purchase or rental of radonmitigation supplies.

A.3.1 111111111immEildli

Drills capable of drilling boles through concreteslabs of at least 3/11- to 1 -inch in diameter areuseful for subslab pressure, communication, andradon measureaMM. The suction hole shouldbe 1-inch or last it diameter, and thecommunkadon tart bole are usually 1/4- to 3/8-inch in diameter. The inexpeashv hemmerdrills sold in hardware stores are oftenincapable of drilling through concrete which hashard aggregate embedded in it Professionalquality, lightweight hammer drills with splinebits are recommended. This type of drill costsapproximately 5250.

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A.3.2 Alum

Most of the shop -type vacuum systems can drawa vacuum of 60- to 120-inches WC and have amaximum air flow of about 100 cfm. This isquite adequate for inducing flow through drilledholes approximately 1 1/2-inches in diameter forcommunication tests. These vacuums areavailable for $40 to S250.

A.3.3 Continuous Radon Monitor

Continuous radon monitoring (typicallyaveraging at 1-hour intervals) is very useful inevaluating the effects of HVAC interactions onschool radon levels. Pylon, Femto Tech, and AtEase are types of continuous monitorscommonly used. A number of school systemshave purchased continuous radon monitors toaid in their school mitigation work. Acontinuous monitor allows each stage to beevaluated quickly when mitigation is performedin stages or a number of rooms need to bemeasured.

A.3.4 Grab-Sample Radon Monitor

In order to map sub-slab radon, a radonmonitor is needed that can pump a sample intoits measurement chamber and hold it longenough for a measurement. It is veryconvenient to use a Pylon AB-5 monitor whichhas a built-in pump and scintillation counteralthough a separate pump, Lucas cell, andscintillation counter can be used. Thisinstrument can be used to take grab samplesfrom boles for subsequent counting, or it can beused for continuously 'sniffing' from a series ofholes. The Pylon system costs about $4500.

A.3.5 Pressure Gauge

A sensitive pressure gauge is necessary tomeasure the pressure fields generated by SSDsystems. Pressure differentials as low as 0.001-

inch WC are common. The most sensitiveDwyer Maipsahelic pressure gauge, which costsabout $50, is sensitive only to about 0.01-inchWC. The slant-tube manometer is difficult toreed, to set up, and to transport. It costs about$100 and has a sensitivity of about 0.001-inchWC. The best type of pressure pup for these

33

measurements is the electronic digitalmicromanometer which can read from 0.001. to20inches WC. These micromanometers costabout S1500.

A.3.6 AirFlow Indicator%

The direction of pressure or air flow in a teathole can provide an indication of systemperformance even if it cannot be measured.Smoke pencils or guns are most commonly usedas now or pressure indicators. The smoke isgenerated by a chemical reaction with themoisture in the air and has an acrid odorbecause of its high acid content. Chemicalsmoke is used because it is not associated withheat; therefore, it will respond .inore accuratelyto minimal air flows. The smoke pencils costabout S3 to S4 each and can last a couple ofhours if they are used carefully. A refillablesmoke gun is also available for about S70.

A.3.7 AirFlow Meters,

Measuring air flow through HVAC registersrequires a 'flow hood' which costs from 51500to S4000. These devices are most commonlyused to balance air flows in large buiWinp. Forair flow measurements in ducts or pipes, a Picottube (about SW) can be used in conjunctionwith a sensitive pressure pug& Alternatively, ahot wire or hot film anemometer. costing about5700 to $1.500. can be used. Pinwheelanemometers, vortex shedder:, and mass flowsensors are examples of other air-flow metersthat can also be used.

A.4 INSTALLATION TOOLS

Most of the tools used for installing radonmitigation systems are conventional tools usedby home improvement contractors. The onlyspecialized tool that any be required is a drillto cut 4 to 6Indk boke through the concretefloor slab. The follOwine options are available:

Use a large rotary hammer drill, costingabout $400, which has a chisel actionand regular drill bits. Experience showsthat in about 20 Manus this drill canmake a large hole by drilling a circular

pattern of smaller holes and punchingthe core out with the chisel.

Use a hammer drill with a carbide corebit. The carbide core bits are expensive(as much as $800) and may not beavailable for your drill in larger sizediameters. They can drill a neat hole inabout 10 minutes.

Use a core drill with diamond bits andwater cooling. This equipment costs asmuch as $2000 and is very heavy andbulky. However, it is the fastest way todrill precise holes in concrete.

AU of these toots can usually be rented fromtool rental shops. It may be economical to hirea core drilling company to come to yourlocation with a diamond core drill if you have anumber of holes to drill.

A.S SCHOOL SSD INSTALLATIONVARIATIONS

All SSD installations should have the exhaustpipe exiting the building shell. The fan shouldbe mounted on the pipe outside the buildingshell to avoid leakage of the radonladen airfrom mks in the Di or from the exhaust endpipe which is under positive pressure. EPArecommends that the system exhaust point beinstalled above roof level and be situated toavoid any possible human exposure to highradon levels from the SSD vented soil gas. Forany type of fan mount, extreme care should betaken to prevent high concentraticns of radonfrom reentering the building through HVACfresh-air intakes, windows, doors, or any otheropening to the building interior. Followingare the types of installations and theiradvantages and disadvantage, which have beenused in schools.

A.5.1 Pedestal Fan on Roof

In this type of installation the pipe penetratesthe roof and connects to a pedestal fan.Disadvantages of this type of installation are theneed to construct and seal a pedestal on theroof for the tall to be mounted on and the need

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to cut a hole in the root (This may lead toroot leaks or may invalidate warranties on theroof.) Advantages are a vertical pipe runwithout high miaow bends, and the lowvisibility (aesthetics) of the installation.

A.5.2 ItkLine Fan on Side Walt

In this type of installation the pipe penetratesthe side wall and an in-line fan is mountedvertically on the pipe. Disadvantages of thistype of installation are the necessity of securingthe fan and the pipe and the potential fordamage or injury if someone climbs the pipe.Advantages are the ease In venting above theroof line and the fact that the roof is notpenetrated.

A.5.3 pedestal Fain on Side Walt

In this type of installation the pipe penetratesthe side wall and discharges horizontally with a

t.

34

pedestal fan mounted on the wall. A significantdisadvantage of this type of installation is thepossibility of someone coming into contact withthe discharge if the fan is not mounted highenough or radon from the discharge leakingback into the building through HVAC freshairintakes, windows, doors, or any other openingsto the building interior. An advantage is thelack of root penetration.

A.5.4 in-Line Fan Above Suspended Ceiling

In this type of installation the pipe penetratesthe roof and connects to a fan which ismounted inside the building above thesuspended ceiling. This is generally notacceptable because of possible leakage from thefan or adt pipe inside the building. Any radonleakage could be distributed throughout thebuilding it the area above the suspended ceilingis a return plenum for the HVAC system.

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APPENDIX 8: SCHOOL MITIGATION CASE STUDIES

These case studies illustrate the staged approachthat characterizes many radon mitigationprojects in large buildings and complex houses.Instead of eying to solve the radon problem inan initial step, most of these projects consistedof multiple stages where one solution wasattempted and then the results were evaluatedbefore initiating the next stage. The casestudies show examples of the step-by-stepprocedure for radon reduction in schools. Someof these projects (Schools A, B, C, D, E, F, 0,and H) were previously documented in thetechnical paper 'Radon Reduction Systems inSchools" (Saum, Craig. and Leovic).

School A: Prince Georee's County. MD

This school had a sophisticated dual-fan HVACsystem that produced unbalanced flow andexacerbated a radon problem in several rooms.Sealing of cracks and replacement of the HVACfan were tried without much effect on the radonlevels. SSD systems will be installed in therooms with the highest radon levels since theproblem of room depressurization could not bereadily eliminated.

A.1 School Description

The school building, which was built in 1969, istwo-story, slab-on-grade construction. It uses alarge dual-fan air handling system for HVAC.Each room has separate supply and returnlouvered vents in the suspended ceiling, TheHVAC system is designed to operatecontinuously during occupied hours and toprovide positive pressurization in all rooms.

A.2 Initial Radon Tests

Radon levels in la school were initiallymeasured in February OIL One classroomtested above 40 KUL, a teachers' lounge testedabove 20 pCVL, and several other classroomstested between 4 and 20 pC1/1.

A.3 Building Plan Inspection

The foundation drawings all for a 4-inch gravelbed and a 6-mil plastic vapor barrier under a

35

4-Inch slab. A vrinch expansion joint runsacross the entire building. The footings runbelow virtually all interior and exterior walls.Square footings support columns.

The HVAC system fans have a rated capacity of51,000 cfm of air supply and 34.000 cfm ofreturn air. This would result in positivepressure in all rooms if the system wereproperly balanced.

A.4 Walk-Through Building Inspection

Examination of the airhandling system showedthat the air supply fan had been damaged andpart of the housing cut away; this resulted in agreat loss of capacity. It was determined thatthe distribution fan was actually supplying lessair than the return air fan was removing; thisMilted in a negative pressure in many rooms.

The room with the highest radon level had thegreatest negative pressure and also had a verylarge floorto-wall crack along one wall. Thisparticular Doorto-wall crack was an expansionjoint where two parts of the building werejoined. The expansion joint had disintegratedand the two building sections appeared to haveseparated an additional leaving a full1-inch gap between the floor and wall. This gapwas concealed by an aluminum angle ironinstalled when the building was built. Theexpansion joint and the angle iron continuedvertically up both corners so that they wereserving as an expansion/contraction jointbetween the two parts of the building.

AS PreMitigation Diagnostics

Pressure measurements indicated that many ofthe rooms were under negative pressure whenboth the supply and return fans were inoperation. The room with the highest radonlevel measured 0.060-inch WC negative pressure(relative to the subelab). There was a goodcorrelation between negative pressure and radonlevels in all rooms, with the highest radon levelsin the rooms with the highest negativepressures. All rooms in the school with anyamount of positive pressure had low radon

367;

levels, Subs lab radon levels were about 500pCi/L in all rooms. When the return air fanwas turned off, the pressure in all roomsbecame positive and radon levels decreased toless than 2 pCi/L.

A.6 Temporary Mitigation

As a temporary solution to reduce radon levels,the return air fan was left off and the HVACsystem operated with only the air distributionfan. Under these conditions all rooms showedpositive pressure and had radon levels below 2pCi/L.

A.7 First - Stage Mitigation

The floor-to-wall building evansion crack wassealed with a backer rod and polyurethanecaulking. This sealing decreased radon levelsonly slightly when both fans were off, whichindicated that there were other soil gas entrypoints in the room. This poor result fromsealing a major crack was surprising becausethis crack was about 1-inch wide and soil gaswith SOO pCi/L flowed out of it when thepressure was negative.

A.8 Second-Stage Mitigation

Little effect was seen on the negative pressuresin the problem rooms although the damagedsupply fan was replaced. Building personnelhave attempted to identify the cause of the flowimbalance to these rooms. This will be furtherinvestigated.

A.9 Third-Stage Mitigation

A decision was made to install SSD systems inthe two rooms with the highest radon levelssince an HVAC modification was not found tosolve the negative prows problem in therooms. Installed= of SSD systems would alsoreduce radon any when the air handlers arenot operating daring night or weekend setbacks.T3B fans were instilled on 6-inch pipes in thetwo rooms with the highest radon levels. Thereturn air grill was permanently disconnectedfrom the return air duct in the teacher's loungeto alleviate the problem there. Since the loungeis used for smoking, it is probably not a good

4,)

. , _ _

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3;

idea to recirculate the air. The return grill isnow directly vented to the outdoors.Post- mitigation tests from this stage are not yetavailable.

A.10 Conclusions

Although mitigation of this school is not yetcomplete, SSD in this case appeared to be amore reliable solution to the radon problemthan crack sealing or HVAC modifications.SSD should solve the radon problem bothduring the day while the HVAC system isturned on and during the night when it isturned off.

School B: WashIngto Comm MD,

This is an trample of a school with a complexradon problem that was mitigated in multiplesteps. A large number of SSD suction pointshad to be used because of the school's complexfooting structure and poor aggrepte. Themitigation performance was evaluated byretesting as each suction system was installed orimproved with a larger fan, larger pipe, orlarger subelab cavity. With hindsight it is clearthat some of these steps could have beenconsolidated; radon mitirtion is not an exactscience and it is often. nelicial to try a simplesolution and evaluate the results beforecontinuing. In this case, the simplest solutionwas installing a single suction point in thecenter of the basement slab near the highestconcentrations of subslab radon. Although thissingle suction point did provide considerableradon reduction in the basement, it wasnecessary to install several other suction pointsaround the edges of the slabs to bring the levelswell below 4 pCi/L.

B.1 School Description

This is a small school, 80 by 150 feet, built onthe side of a hill. The school has a 21 by 150foot walk-out basement along its lower side.The unesmvated area is slab.on-grade, with theslab extending over the basement area andresting on steel-bar joists. The foundation wallsare contracted of concrete blocb. The interiorwalls of the basement support the end of the

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bar joists and the slab. This wall is not paintedor waterproofed on either side. Separatesingle-fan, roof-mounted HVAC systems withceiling-mounted duct work are provided for thebasement and upstairs.

5.2 Initial Radon Tests

Charcoal canister measurements taken over aweekend in March 1988 averaged 10.5 pCi/L inthe basement and 43 pa/L on the first floor.It is unknown how the air handlers wereoperating during the test. All rooms wereretested over a weekend in May 1988 with airhandlers turned oft Measurements ranged from78 to 82 pCi/l. in the basement and from 18 to33 pa/L on the first floor.

B.3 Building Plan Inspection

The building pins indicate that the first floorand unfinished easement were constructed in1971. In 1976 the basement was converted intoclassrooms and a slab-on-grade greenhouse wasadded. The foundation plans show a complexfooting structure upstairs that would limit theextent of pressure Das from SSD ststems.There are, however, basement footings at theperiphery of the slab which would allow anybasement SSD pressure fields to be limited onlyby the aggregate porosity. One specificationnotes that 'completed Mt prior to laying offloor slabs, shall have density and compressivevalue of not leas than 95% of the normalundisturbed soil value....The fill directly underconcrete slabs on grade shall be clean crushedlimestone; 1/2 in. minimum, 1 in. maximum sizeleveled, compacted to 4 in. minimum thicknessor as shown on drawings.* No soil test resultsare provided.

B.4 Wa ik-Throngh Building Inspection

The upstairs and domain are mostly openareas subdivided by movable low partitions.The HVAC supply and return pills arepositioned so that there are only a few officesand storage areas where the HVAC systemcould cause depreourization. No major radonentry routes were noted other than typical small(1/8-inch) credo between the walls and the floorslabs and expansion joints.

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B.5 Pre-Widation Diagnostics

Radon mapping was conducted by drilling smallholes in the floor and walls and "sniffing" with Jcontinuous radon monitor. These tests resultedin measurements of about 1500 pCi/L in thefloor and block walls around the central stairwell. Other floor and wall samples were below500

Hourly continuous radon monitoring overseveral weeks; showed that radon levels were lowwhen the HVAC systems were operating.During nights and weekends when the systemwas in a 'setback' mode, radon levels rose quiterapidly to as high as 150 pCi/L downstairs and80 pCUL upstairs. Pressure measurementsthrough holes in the slab showed that theHVAC systems resulted in small positivepressures within the building that providedcomplete remediation as long as they wereoperating. However, the HVAC fans onlyoperated when heating or cooling wasdemanded; during mild weather they seldomoperated. The March charcoal measurementswere made during cold weather that probably=gutted more HVAC operation than the Maytests which showed much higher radon levels.Communication tests showed that a trace ofsuction could be measured across 20-feet of thecenter of the basement floor and in the nearbywalls. This suction confirmed that someaggregate was present, that the permeability wasmarginal, and that an SSD system might be ableto produce significant mitigation.

B.6 Temporary Mitigation

When the radon problem was discovered inMatch, the students were moved out of thebasement classrooms where the levels were thehighest. Tests in May showed the levelsincreasing upstairs, probably because of thediminished cycling of the HVAC system in mildweather. For temporary mitigation, until theschool recessed for the summer, the HVAC fanswere turned on continuously both upstairs anddownstairs when the building was occupied.Although this provided complete mitigationunder spring conditions, it was not consideredan acceptable permanent solution because of theincreased wear on the HVAC fans and the

unknown level of performance in the winter.Even with closed fresh-air dampers, a very slightpositive pressure which produced completeremedlation was generated in the building. IfHVAC mitigation had not been possible, oneoption might have been to install a largeportable fan which would have been used toblow air in through an open door while classeswere In session, or the school might have beenclosed early for the summer.

8.7 First-Stage Mitigation

A 4-inch diameter suction hole was drilledthrough the slab in a centrally located basementcloset near the highest subslab radonmeasurements. The aggregate exposed by thishole was about 4-inches deep; it contained finematerial which limited its permeability. A1-foot diameter cavity was excavated in theaggregate and a 4-inch diameter suction pipewas installed across a dropped ceiling, out aback wall on the downhill side, and vented upabove the roof line. Larger 6-inch diameterpipe would have been installed to allow moreair flow and a bigger fan, but the clearanceabove the suspended ceiling was too low. AKanalflakt T2 in -line fan was coupled to thepipe to provide about 1-inch WC of suction inthe subsiab cavity. After several days ofoperation, a continuous radon monitor showeda drop in the basement radon to about 40pCi/L These tests had to be made during theweekend when the temporary mitigation schemeinvolving the HVAC system could bediscontinued without exposing the students tohigh radon levels. The upstairs levels droppedto about 20 pCi/L (All air-handlers were off.)These results suggested that the SSD system hada significant effect on the major radon source inthe building, but other sources remained to bemitigated and/or the main source was notcompletely mitipMaL

0.8 Seinad-Seaga Mitigation

is order to improve the performance of thesingle suction-point system, the subslab cavitywas expanded from about 1-foot in diameter toabout 2 by 3 feet. This significantly increasedthe air flow as indicated by a drop in cavitypressure from about 1- to 0.5-inch WC. It also

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doubled the pressure field under the slab asindicated by the fact that the pressures in a hole13-feet from the suction point increased from0.012 to 0.025-inch WC. Radon levels upstairsand downstairs also decreased slightly.

8.9 Third-Stage Mitigation

In the next attempt to increase the performanceof the single point SSD system in the basement.the fan was increased from a ICanalilakt T2 to aT38. This increased the suction in the cavityfrom 0.S to 0.7-Inch WC which was not as largeas might be expected since the T3B is capableof moving more than twice the air flow of theT2 at the same pressure. The increase that wassmaller than expected its subsiab pressure isprobably due to the flow restriction andpressure loss in de 4-inch diameter pipe. Aslight decrease in raison levels was noted, butthe levels downstairs and upstairs were stillabout 20 and 15 pCi/L, respectively, after theHVAC fans were off for 24 homy

B.10 Fourth-Stage Mitigation

Since some radon was thought to be comingfrom under the first door slab, a suction systemwas installed near the woodsorldng shop wherethe highest upstairs subslab air measurementshad been taken. A T2 fan and 4-inch pipe wereinstalled and a or Duns was coupled to thepipe and sealed so that a second suction pointcould be added to this system. The subslabaggregate was found to be only 2 inches deepand full of fine material, limiting itspermeability. Continuous radon measurementsshowed very little change after the system wasturned on.

8.11 Fifth-Stage Mitigation

To improve the performance of the upstairssystem, a second suction point was installedabout 20 feet away from the first. In addition,the fan was replaced with a ne and the pipenear the fan was replaced with 6-inch diameterpipe to handle the increased flow from the twosuction pipes. The initial suction point Cavitybeneath the slab was increased from 1-foot indiameter to 3 by 2 feet to increase the subslab

air flow. A slight decrease in the upstairs radonlevels was observed.

8.12 Sixth-Star Mitigation

In order to complete the mitigation systemdownstairs, two more suction systems wereInstalled at the ends of the basement. Thesesystems used 4-inch pipe and 17 fans, withabout 1-foot cavities in the aggregate beneaththe slab. In addition, all three downstairssystems had "T" fittings installed in the pipeabout 6-feet above the floor; horizontal 4-inchpipes penetrated the hollow concrete blockwalls. Unfortunately, the wall suction createdso much air flow in the pipes that the subslabcavity pressures in all the systems fell to about0.2-inch WC, and the continuous radon monitorin the basement showed that the net result wasa significant increase in basement radon.

B.13 Seventh-Stage Mitigation

When the wall suction pipes were cut andsealed, the subslab cavity pressures in all thesystems rose to about 0.7-inch WC and thebasement continuous radon monitor showedlevels below 2 pCUL Pressure fieldmeasurements in the basement showedmeasurable depressurization under all of theslab.

B.14 Eighth -Stage Mitigation

The upstairs radon levels were still observed torange from 4 to 10 pCUL, so three more subslabsuction points were installed along the uphillside of the upstairs slab. These systems wereseparated by about 30 feet and consisted of6-inch pipe with two points maidfolded to a T2fan and a third connected to a 0V9wall-mounted fa that discharged horizontallyabout 10 feet off the pound.

B.13 Ninth-Stage Mitigation

Continuous radon measurements showed thatsome peaks above 4 pCUL wetre associated withthe greenhouse area which had twin of the threenew suction points. After the fan on thesepoints was increased to a T4, the radon levelsremained below 2 pCUL.

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8.16 Cost Estimates

The cost estimates given below are higher thanthe actual expenses because of the researchnature of this project, but the followingbreakdown may be useful:

1. Labor for SSD installations:

6 SSD Systems @ 2 person days persystem 12 person days.

2. Parts cost for SSD installations (fans.pipe, electrical):

6 SSD Systems @ 1500 per system$3,000.

3. Labor for post-mitigation testing:

9 stages @ 0.5 person day fordistribution and pickup in 4.5 persondays

4. Charcoal canisters for post-mitigationtesting at each stage:

9 stages with 10 canisters each @ SIOper canister S900

5. Pre - mitigation diagnostic work byexperienced home mitigator:

2 days @ MO per day $1000

6. Continuous radon monitoring byconsultant to monitor progress:

30 days @ $100/ per day $3000

The total is 16.5 person days of labor and$7,900 in parts and consultant tees. Sincecontinuous radon monitors are available forabout $3000, it may be cost effective for schoolsystems with extensive radon problems topurchase their own monitors.

B.17 Conclusioa

Houses with marginal subslab porosity can oftenbe mitigated with SSD if enough suction pointscan be installed. This school required a similar

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mitigation system. Winter testing with longterm alpha-track monitors measure/I blow 4pCUL with most of the rooms measuring below2 pLUL. Pressure pages were placed on mostof the suction pips so that the fan performancecan be quickly checked.

school C: Washington County. MD

This successful school mitigation project is anexample where large SSD fans can be used tomitigate large slab areas with 6-inch diameterpipe used as a manifold to connect the fan toseveral 4-inch diameter pipes that penetrate theslab.

C.1 School Description

This entire school building is slab -on -grade withblock walls and no utilities below grade exceptsanitary sewers. The original building wasconstructed in 1956 and has four area airhandlers for heating and ventilating with acentral boiler room. A classroom wing wasadded in 1968 and unit ventilators were used ineach room. No pan of the building isair-conditioned.

C.2 Initial Radon Tests

Elevated radon levels were found in the lockerrooms on each side of the gymnasium in theoriginal building and in the new classroom wing.The April 1988 screening tests with charcoalcanisters showed that 21 of 72 tests were above4 pCUL: 7 were above 8 pCUL, and 1 was above20 pCUL (26.7). The highest levels were in thenew classroom wing.

C.3 Pre-Mitiption Dimmed=

Although the locker rooms and gymnasium areon the same air hemeer, the gymnuiummeasured LS pall, whereas the OW lockerroom measured 4.9 to 63 pa& and the boys'locker room measured 5.3 co 19 pCIIL Furtherexamination Mimed that each locker momarea had a large exhaust fan to remove odorsand shower steam. Differential pressuremeasurements (using a micromanometer), withthe air handler and exhaust tans operating,

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correlated with the radon levels showing thatthe gym pressure was slightly positive, the girls'locker room area slightly negative, and the boys'locker room area significantly negative.

In April 1988 weekend charcoal canistermeasurements were made in the new classroomwing with the unit ventilators turned off. Allrooms but one We above 4 pCUL.; a room inthe northeast corner of the building measured26.7 pCIIL Radon levels decreased from northto south in this wing as did subslab radonlevels. A continuous radon monitor was placedin the mom with the highest radon levels.When the unit ventilator was off, levels above20 pCUL, were reached nightly but remainedbelow 2 pCi/L when the unit ventilator wasoperating continuously. Pressure measurementsmade with a micromanometer confirmed thatthe unit ventilator was pressurizing the roomslightly.

C.4 First -Stage Mitigation

Construction plans showed that each lockerroom area was a continuous slab with aggregatebeneath it. As a result, a 6-inch subslab suctionpoint was placed in each of the two lockerroom areas with a lefoot diameter subslab holeand a Kanalflakt OV-9 fan (rated at 200 cfm at0.75 inch static pressure). Both locker roomareas measured less than 4 pCUL with theexhaust fans and the subslab depressurizationsystems operating.

In the new wing, the unit ventilators are turnedoff at night except in extremely cold weatherwhen they are cycled. It was decidid to install

subslab depressurization points in this wingto provide miciption when the unit ventilatorswere not muted. The two inch pipes wereinstalled is the hall and manifokkd with anaboveceiling 6-indt pipe running to aKusalflakt OV-12 fan (rated at 510 cfm at OAinch static pressure) at the north end of thebuilding. One suction point was installed with a3-foot diameter subslab bole about 20 feet fromthe lust end of the hall. The other suctionpoint was Walled with a 1-foot diametersubslab bole about 60 feet from the end of theWI. Pressure field amnion measurementsindicated that the two fields overlapped: all slab

C.

areas of the wing, except the most southernclassrooms, were depressurized to the outsidewalls.

C5 Second-Stage Mitigation

Since the new wing pressure field =tensionaround the 1foot diameter suction hole was notas great as around the 3-foot suction hole, the1foot sulwiab suction hole was increased to 3feet in diameter. This extended the measurabledepressurization area by 10 feet to the south,which was sufficient to reach the last twoclassrooms. The amount of depressurization inthe test holes in all directions around thesuction point was doubled. With the subslabdepressurization system operating, radon levelswere below 4 pCUL in all classrooms with theunit ventilator fans off.

C.6 Conclusion

This school was relatively simple to mitigateand, although the subslab communication wasnot very good due to low quality aggregate, thethree SSD systems performed adequatelybecause of large fans, large diameter pipe, andlarge subslab suction pits.

School Di Wuhirwton County. MQ

This successful school mitigation showed thatschools with radiant heating coils in the slabcan be mitigated with SSD if a deep layer ofaggregate is under the slab. The project wasexpected to be difficult because of the limitednumber of places where the slab could bepenetrated without the danger of drillingthrough a hot water pipe. A newer section ofthe school, heated with unit vendlators, wasmitigated with two aulti-point SSD systems.

D.1 School Demipdos

The original building of this school was built in1958 and is boated with hot water radiant heatin the slab. In 1978 a kindergarten room wasadded in an of set to the original building, anda separate building (Building B) was built whichcontains four classrooms, a library, a teachers'

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workroom, a conference room, and restrooms.The kindergarten room is heated with hot waterradiant heat, and the new building is heatedwith unit ventilators. Office space in theoriginal building is air-conditioned with awindow unit. No other area of either buildingis air-conditioned.

The original building has two 3600 cfmroof-mounted fans that can be used to exhaustair in plenums over the ball ceiling. Each roomhas a ceiling vent which connects to these hallplenums. However, the exhaust fans are neverused. Consequently, the building has no activeventilation system.

D.2 Initial Radon Tests

All rooms in both buildinp were tested withcharcoal canisters over a weekend in midAprilOf 24 tests, 21 were over 4 pCUL. 16 were over8 pCUL, and 3 were over 20 pCUL. The eightrooms in Building B measured between 17 and20 pa/L. It is believed that the unitventilators were off during the testing weekend.but this could not be confirmed. Seven tests inthe classrooms, library, and multipurpose roomin the original building measured between 12and 23 pCUL

Di Building Plan Inspection

Plans showed that the initial building andkindergarten addition had 6 inches of aggregateunder a 6inch thick slab containing hot waterpipes for heating. Building B had 4 inches ofaggregate under a 4-inch slab.

D.4 Pre-Midgation Diagnostic

A continuous radon monitor was placed in oneof the classrooms in Building B to meascre theeffect of unit ventilator operation on radonentry. It was found that radon levels would riseovernight to above 20 pCUL with the ventilatoroff but would remain below 2 pCUL with theventilators operating. Again, this shows that aunit ventilator can reduce radon levels bypressurizing the room slightly. When runcontinuously this type of unit ventilator canprevent radon entry.

D.5 First-Stage Mitigation

Since the Building B ventilators are off duringnight setback a fanr-pdint, two -fan subslabdepressurization system was installed to redtceradon entry. The risen are 4inch pipesconnected to two 6-inch manifold pipes abovethe dropped ceiling. (No risen are manifoldedto each pipe.) A Kanalflakt OV9 fan (rated at200 cfm at 0.75inch static pressure) is used toexhaust each system. Pressure field emulsionmeasurements indicated that subslabdepressurization extended 50 feet, the minimumdistance necessity to reach all pans of the slab.

With the Building B subslab system operatingand the unit ventilators off, all Eooms .emainedbelow 4 pCiiL. However, based on thepressure field extension measurements, thesystem may be of marginal value during coldweather. If radon levels rise above 4 pCi/L it isbelieved that subslab depressurization can beimproved by sealing the floorto-wall opening.A Ypinch expansion Joint around all of the slabsin the building is deteriorating, leavingsignificant opening to the subslab. Thisprobably leads to some short-circuiting of thesubslab depressurization system.

D.6 Second-Stage Mitigation

Subs lab suction on this original building (theintraslab radiantheat building) was a challengesince construction plans showed that the hotwater pipes in the slab were separated by nomore than 15 inches over the entire building.As a result, it was diffladt to locate an areawhere a 6inch subslab suction point could beput through the slab without running the risk ofdamaging a hot water pipe. Building plansidentified a 3-foot square area without waterpipes in each roll. A hole was successfully cutthrough one of thus areas. The plans indicatedthat the wave was a minimum of 6 inchesdeep, much deeper than at any other schoolexamined. A 6-inch Suction point was installedwith a Moot diameter bole with a ICanalflaktKTR15048 fin (rated at 510 can at 0.75-inchstatic pressure). Pressure field egression was fargreater than expected; depressurization could bemeasured as far as 90 feet from the suctionhole. These results were surprising since the

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aggregate appeared to be some type of 'crusherrun' aggrepte with a certain amount of fines.However, in leveling the aggregate beforepouring the concrete, it is probable that most ofthe fines had sifted to the lower portion of theaggress, a bed leaving a fairly thick area oflarge-diameter aggregate immediately under theCOnante. It is believed that this layer of coarsestone enhanced pressure field extension; thiswill be studied further. It appears that this onesuction point will solve the problem in theoriginal building. If this one suction point ismot sufedent to treat the entire building, it maytake a second point, operated on a separate fan,to completely mitigate the building.

Since the kindergarten room is an addition, thesubslab area does no communicate with theoriginal building. Consequently, a suction pointwas put in a closet adjacent to a restroomwhere the hot water pipes were spaced 24inches apart to clear the commode's sewer line.A Kanalflakt fen (rated at 140 dm at 0.75inch static pressure) installed on this pointlowered rube levels to below 2 pCitl. Nopressure field extension measurements weremade for fear of damaging a heating water pipe.

This school has been retested over the winter todetermine if the SSD systems continue tomitigate during cold weather conditions; resultsshould be available soon.

D.7 Conclusion

The ease of mitigating several thousand squarefeet with one SSD suction point in the oldersection of this school was an encouraging result.Building B was a standard installation with twosuction points on each of two SSD systems.

Scheel Es Fairfax County. VA

This successful school mitigation project showedthat radon problems can be aggravated byexhaust-only ventilation systems that producecontinuous negative pressures in all rooms(relative to the subslab am). However, it wasalso shown that, with sufficient subslabpermeability, SSD systems can achieve successful

radon mitigation under these adverse conditionsof negative pressure.

E.1 School Description

This slabongrade building is L-shaped," andeach wing has a central hall with classrooms oneach side. The rooms are heated by hot waterfin heaters along the outside walls. Each roomhad ceiling exhaust vents into a plenum over themoms and halls. Since there was no supply airfan, the roil-mounted exhaust fans in thisplenum caused severe depressurisation (0.060Inch WC negative pressure) of the entirebuilding, and any makeup air entered thehuildins only through infiltration induced by thedcpmsurizstion.

The building was designed so that eachclassroom would be ventilated adequately only ifone of the windows was left open.Unfortunately, the severe depressurization wasalso drawing subslab soil gas containing radoninto the building.

E.2 Initial Radon Tests

Tests during the fall of 1967 in this school werethe first to suggest that radon levels inclassrooms varied widely from room to room.and that the test results were difficult to predictfrom room location and construction. Initially,charcoal screening tests were conducted in a fewclassrooms with the highest test showingapprotdmately 6 pCUL. Subsequent tests in allclassrooms by the PTA showed severalclassrooms over 20 pa/L, The nvo endclassrooms of the southwest wing had levels of22 and 17 pCUL with three other rooms above4 pCUL The southeast wing had three roomswith moderately elevated levels of 5, 6, and 7pCi/L

E.3 Building Pin Inspection

The building plans Gad specifications called for4 inches of aggregate under the slab. Thefoundation plans showed that the slab wasthicker along the hall between the classrooms.

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E.4 Temporary Mitigation

The students were moved out of the rooms withthe highest radon levels until the problem couldbe corrected. Since there was little experi,..;nrewith school radon mitigation in Fairfax Countyat this time, it was not known how long (twould take to EX the proolott.

E.3 PreMitigation Diagnostics

Subslab communication tests and radon testswere performed to locate the radon sources andto determine whether SSD was a possibility.Radon kwels from 25 to 2000 pCifi., were foundunder the slab and were consistent with thelocation of rooms with highest screeningmeasurements. The subslab communication wasfound to be good, except in the thickened areaof the Slab. Separate suction points would haveto be placed on each side of the hell. Therewas good communication under the interiorwalls that art; pap:W.101u to the hall. Thiswas consistent with the foundation plans thatshowed that these walls were nonloadbearing.

E.6 First-Stage Mitigation

A number of mitigation strategies wereconsidered, including reversal of the exhausttans to create pressurization, drilling ventilationholes through the walls behind the radiators toprovide mote fresh air, and replacing the entireHVAC system with a positive pressurizationsystem. Before these expensive solutions wereattempted, it was decided to try the simpletechniques recommended by the EPA for housemidpdos: eliminadag depressurization, sealingcracks, sal SSD. For eliminatingdepressurization, the HVAC exhaust fans wereturned off and the rooms were retested todetermine if the building could be mitigated bysimply removing the nepte pressure.Surprisingly, some of the moms were still above10 pCUL under these conditions. It seems thatthe lower prom probably reduced radon entryrates, but it also reduced the entry of fresh airthat was diluting the radon.

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E.7 Second-Stage Mitigation

The rooms with the highest radon levels werefound to have cradle beteeen the floor and wallthat varied from to a inch wide. These crackswere carefully sealed and re-testing of the roomindicated a reduction of radon levels from 0 to50 percent.

It is not unusual to get marginal mitigationresults from crack sealing in houses. This isthought to be due to the difficulty in sealing allthe radon entry Touts such as porous hollowblock walls. In addition, the radon levels oftenbuild up behind effective sealants, so that anyunsealed leaks may provide more radon.

E.8 Third-Stage Mitigation

Subslab suction points were put in the two endrooms of the southwest wing. The subslabsuction points were manifolded overhead andconnected to one Kanalflskt CiD9 fan (rated at310 dm at 0.75-inch static pressure). Subslabexcavation revealed that the aggregate waspresent and that it did not have significant finematerial that would impede air flow. With thisSSD system in operation there was goodpressure field extension to at least three roomson each side ..f the hall. In addition, all of thefloorto-wall joints were carefully sealed in all ofthe rooms of both wings. Following sealing andinstallation of the two suction points, all of therooms in both wings tested below 4

E.9 Fourth-Stage Mitigation

During December 1988, shortterm testsrevealed that radon levels we= spin above 4pall. (despite the previous sealing work) in thesoutheast wing that did not have an SSDinstalled. Althoeik tap term tests indicatedthat the long-tem swage, "ere below 4 paiL.school personnel decided to install an SSDsystem in this wing. This work has beencompleted, and all classrooms are below 4pCUL

E.10 Conclusion

Mitigation of this school showed that, sincesubslab permeability was good, SSD was

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applicable despite the large size and complexventilation system. Sealing and the reduction oidepreuurization were marginally effective, butSSD was very effective despite thedepressurization of the building by the HVACexhaust fans.

School": Washineton County. MD

This ongoing, initially unsuccessful schoolmitigation project shows that mistakes can bemade easily in selecting an appropriate radonmitigation method. In this case, an attempt touse SSD to overcome subslab return air ductleakage was a failure; a more expensive solutionwill probably be MOSSary.

F.1 Initial Radon Tests

In April 1988, 39 charcoal canister radon testsshowed that 28 were above 4 pCi/L, 8 wereabove 8 pail., and none were above 20 pa/L.All of the screening and confirmation tests weremade when the building was unoccupied and theHVAC system was turned off.

F.2 Building Plan Inspection

The original school was built in 1954, andadditions were made in 1964. Both areslabon-grade construction. The additions havean HVAC system with return air ducts that areunderneath the slab. The foundation plans andspecifications all for 4 inches of aggregateunder the slabs.

F.3 PreMitigation Diagnostia

Radon grab samples showed about 20 pCl/L inthe HVAC supply sir when the system wasturned on. This indicated that the return airducts under the slab were drawing in soil gasand recirculating it through the school. Subsiabpressure measurements indicated a pressure fieldthat ranged from 0.1- to 0.001inch WC ofnegative pressure. The largest pressures werenearest the return air exhaust vent that went upto the root mounted fan system. Thesemeasurements suggested that if a SSD systemwere installed which would produce a largercompeting pressure under the slab, the soil gas

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could not enter the cracks in the return airpiPes.

F.4 Fist-Stage Mitigation

A Kanalflakt OV9 fan was mounted on theroof, =fleeted by a 6-Inch manifold pipe totwo 4-inch diameter pipes. Suction points forthese smaller pipes were drilled though the slabnear the return exhaust suck in order tomaximize the suction where diagnostics hadindicated that the return air subslab suction wasthe highest. These slab penetrations uncoveredgood aggregate without excessive fine materiaL

However, it soon became obvious that this SSDsystem could not overcome radon entry into thereturn air ducts. The diagnostic measurementsof the return air pressure field had been madethrough holes drilled through the slab and notthrough holes drilled through the actual returnair pipe under the slab. When this pipe wasexposed through the holes drilled for the 4-inchpipe, pressure measurements showed 0.8.inchWC inside the pipe. The diagnostics hadconfused the small subelab negative pressurethat was caused by duct leakage with the muchlarger negative pressure in the pipe. It is veryunlikely that a SSD system could realisticallydepressurize all areas of the slab to a level(approximately 0.8-inch WC in this case) thatwould be required to prevent soil gas fromentering any cracks in the pipe. Subsequentradon tests indicated that the installed systemhad a negligible effect on the radon levels inthe schooL

F.5 Conclusion

Schools with subsoil) HVAC ductwork create aMajor problem that may require an alternativemitigation approach to SSD. Although it isgenerally a good Mu to ay a simple,inexpensive taftlallea tedudque Mare tryingthe more compile mid expensive techniques,there should be some opulence or theory thatprovides some confidence that the techniquewill work.

A new overhead air-return system is now beinginstalled in this school, and follow up diagnosticmeasurements are planned.

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GLArlinieten County. VA

This successful school mitigation project showedthat schools with minor radon problems in afew rooms may be mitigated by crack sealing orcorrection of HVAC imbalances. However, it isunlikely that these measures would be effectiveflat radon levels significantly over 8 pCl/L sincereductions from these approaches are usuallyabout 50 percent.

0.1 School Description

Half of this older school building is one -storyslab-on -grade the other half is two-story with awalk-out basement. The walls are constructedof hollow blocks and the exterior of the schoolis brick veneer. The HVAC system combinesunit ventilators with a single-fan air handlingsystem with overhead duct work.

0.2 Initial Radon Tests

Initial and follow-up charcoal canister testsshowed only two basement rooms between 4and 8 pCIA., All other rooms were below 4pCl/I. The measurements were made duringunoccupied periods.

0.3 Wallabrough Building Inspection

The HVAC supply vent in one of the problemrooms was found to be inoperative and theother room was found to have a 1/2-inch widebuilding expansion crack that was looselycovered by baseboard molding.

0.4 Pre-Mitigation Diagnostics

Subelab radon levels of 500 to 1000 pCi/L weremeasured in the basement area. A negativepressure in the room with the inoperativesupply vent could be detected by air movementinto the roots when the HVAC fan wasoperating

0.5 First- Stage Mitigation

An HVAC contractor was called in to correctthe HVAC supply deft problem, and thebuilding separation auk was sealed with apourable polyurethane caulk. Atter these

mitigation efforts were complete. continuousradon monitoring and short-term charcoal testsshowed that the MOM with supply ventproblems was below 2 pCi/L, but the room withthe building open** crack still had dailypeaks above 4 pCi/l. Further examination ofthe slab in this room showed an additional ainch wide and 30-foot long crack between thefloor and the wall underneath a unit ventilatorsystem along one wall.

0.6 Second -Stage Mitigation

The unit ventilator coven in the remainingproblem room were removed to pin emus tothe crack and pourable polyurethane caulk wasused to seal it. Continuous monitoring andcharcoal canister tests showed that the radonlevels were now consistently below 4 pa/L.Both problem rooms will be retested over thewinter to determine if the mitigation continuesto be effective.

0.7 Conclusion

When radon levels are slightly elevated (lessthan 8 p0.4.), then mitigation solutions such ascrack sealing and elimination of gross HVACdepressurization may be effective. However, inmany cases these techniques fail to reduce radonlevels by as much as SO percent, and theproblem may recur during the winter. Sealingmay not be very effective because many entryroutes such as porous hollow block wails arehard to seal. Effective sealing causes a higherconcentration of radon to build un behind theseal so that the few remaining entry routes mayleak soil gas with higher radon concentrations.When HVAC depteuurindon is eliminated,there is still a slight depressurization of theupper surface of the slob due to the buoyancyof warmer air in the building (natural stackeffect). The mote auxin and dependablemitigation tecludiple rely on positivepressurization above the stab, or negativepressurization beneath the slab.

a1pllitaLt1011011S9111152611M

This ongoing school mitigation project isattempting to mitigate a combination

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crawl-space/slab-on-grade school. A largeexhaust fan has been installed in the crawl spaceand the radon levels in the crawl space and thebuilding have been slightly reduced. Futureplans call for InaeaFed sir sealing of the crawlspace, retesting of the pressure and radon levels.evaluation of the mitigation effects of theHVAC system, and installation of a subslabsuction system under the slab-on-grade sectionof the school.

H.1 School Description

Half of this single story building is over a crawlspace and the other half is slab-on-grade. TheHVAC system is a single-fan system withoverhead duct work. The exterior of the schoolis brick veneer. All exterior entrances to thecrawl space appear to be sealed.

H.2 Initial Radon Tests

In April 1988, 35 charcoal canister radon testsshowed that 34 were above 4 pCi/L, 15 wereabove 8 pCi/L, and 1 was above 20 pall (23.5pCVL). The radon levels were generally higherin the rooms over the crawl space. All of thescreening and confirmation sew were madewhen the building was unoccupied and theHVAC system was turned off.

H.3 Building Plan Inspection

The original school, which is appradmately150,000 square feet in area, was built in 1936over a crawl space. In 1967 a slab-ongradeaddition was built onto two sides of the oldbuilding. The crawl space has a din floor andthe wooden floor joists rest on a mare ofmasonry walls. The foundation plans andspecifications tor the slab all for 4 inches ofaggregate under the slabs. The addition wasconstructed so that its floor would be at thesame level as the crawl space floor. Retainingwalls were built and shale fill was used to raisethe level.

H.4 Walk - Through Building Inspection

The crawl space is accessible through hatches inthe floor, but the crawl space sire and maze ofsupport walls do not appear to offer good

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access for laying down a ground cover forsubmembrane depressurization (SMD), as Isoften done in hoses built over crawl spaces.Some plumbing pipes are in the crawl space andall Merlin vents appear to have been sealed forsecurity anti to prevent the pipes from freezing.

H.5 PreMitigation Diagnostic

Since there is little experience with radonmitigation of large crawl spaces, there are noguidelines for diagnostic analysis. Blower doortesting of the crawl space was considered, butthe installation of a 500 dm exhaust fan wassimpler to evaluate. Radon grab samp;es takenbefore the fan installation showed about 30pCVL in the crawl space.

H.6 FirstStage Mitigation

A Kane Iflakt OW fan was mounted on one ofthe wooden panels that covered the crawl spacevents. This fan can move 510 dm at 0.0pressure. It was mounted so that it wouldexLaust air from the crawl space. No crawlspace sealing was done before evaluation of thesystem's performance.

The fans were turned off over the Christmasholiday weekend, and continuous radonmonitors were placed in the crawl space and themain office to determine if the crawl spaceexhaust fan was reducing the radon. Themonitoring showed that the crawl space levelsdropped slightly when the fan was running. Inaddition, the office radon seemed to be wellbelow 4 pCVL when school was in scuba andthe HVAC fans were operating. Pressuredifferentials in the crawl space did not changemeasurably (less than 0.001 inch WC) due tocrawl space exhaust fan operation. Calculations

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of these results estimate that there is at least 10square feet of leakage in the crawl spaceenvelope.

Hi Second-Stage Mitigation

The school will be retested with the HVACsystem operating to determine the mitigationeffect. If the HVAC system induces a positivepressure in all parts of the building, then theradon problems may be mitigated while theHVAC fans are operating. Further investigationwill be required to determine if the HVACmitigation can be relied on under all operatingconditions, and whether there is a remainingradon exposure problem to those who use theschool outside of normal operating hours whenthe HVAC fans are off. The crawl spaceexhaust fan seems to be lowering the radonlevels slightly, but it does not seem to becreating much of a pressure barrier to preventsoil gas from moving into the building. Toincrease the depressurization, several large holesbetween the crawl space and the boiler roomwill be sealed.

A SSD system will be installed in theslab-on-grade part of the school. This systemwill be mounted externally by drilling a 6-inchdiameter hole in the retaining wall, Just belowthe slab leveL A ICanalflakt T38 in-line fan willbe mounted on a 6-inch stack that exhaustsabove roof level.

H.8 Conclusion

Several more mitigation stages are anticipated inorder to obtain an effective radon mitigationsystem for this complex school. The finalmitigation system will probably combine anumber of methods due to the school's complexsubstructure.

APPENDIX C: STATE RADON OFFICES AND EPA REGIONALRADIATION PROGRAM OFFICES

C.1 STATE RADON OFFICES

Radiological Health BranchAlabama Department of Public HealthState Office BuildingMontgomery, AL. 36130(205) 261.5313

Alaska Dept. of Health and Social ServicesP.O. Box H-06FJuneau, AK 99811.0613(907) 586.6106

Arizona Radiation Regulatory Agency4814 South 40th StreetPhoenix, AZ 85040(602) 2554845

Div. of Radiation Control and EmergencyManagementArkansas Department of Health4815 Markham StreetLittle Rock, AR 72205.3867(501) 661.2301

Indoor Quality. ProgramCalifornia Department of Health Services2151 Berkeley WayBerkeley, CA 94704(415) 540.2134

Radiation Control DivisionColorado Department of Health4210 East 11th AvenueDenver, CO saw(303) 331.4812

Connecticut Deportment of Health ServicesToxic Hazards NMI150 Washington SerestHanford, Cr 06106(203) 566-3122

Division of Public HealthDelaware Bureau of Environmental HealthP.O. Box 637Dover, DE 19903(302) 736-4731

DC Dept. of Consumer and Regulatory Affairs614 H Street, NW, Room 1014Washington, DC 20001(202) 727.7728

HRS Office of Radiation Control/Radon1317 Witmer' BoulevardTallahassee, FL 32399-0701(904) 488-1525(800) 543-8279 (Consumer inquiries only)

Georgia Dept. of Natural ResourcesEnvironmental Protection Division205 Butler Street, NEFloyd Towers East, Suite 1166Atlanta, GA 30334(404) 6564905

Environmental Protection and Health ServicesDivisionHawaii Department of Health591 Ala Moans BoulevardHonolulu, HI 96813(808) 548.4383

Bureau of Preventive Medicine450 West State StreetFourth FloorBoise, ID 83720(208) 3344927

Illinois Department of Nuclear SafetyIllinois State Board of Health301 Knotts Street

Springfield, IL. 62703(217) 7866399(800) 225.1245

Division of Industrial Hygiene and RadiologicalHealthIndiana State Board of Health1330 W. Michipn StreetP.O. Box 1964Indianarolls, IN 46206-1964(800) 272-9723

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Bureau of Envtonmental HealthIowa Department of Public HealthLucas State Oface BuildingDes Moines, IA 5031943075(800 383.5992

Bureau of Air Quality and Radiation ControlAttention: RadonForbes Field, Building 740Topeka, KS 66620.0110(913) 296.1560

Radiation Control BranchCabinet for Human Resources275 East Main StreetFrankfort, KY 40621(502) 564.3700

Louisiana Nuclear Energy DivisionP.O. Box 14690Baton Rouge, LA 70898.4690(504) 925-4518

Division of Health EngineeringMaine Department of Human ServicesState House Station 10Augusta, ME 04333(207) 2894826

Division of Radiation ControlMaryland Dept. of Health and Mental Hygiene201 W. Preston StreetBaltimore, MD 21201(301) 631-3300(800) 8724666

Radiation Control ProgramMassachusetts Department of Public Health23 Service CenterNorthhampton, MA 01060(413) 5864525(617) 7274214 (Boston)

Michigan Dalmatian of Public HealthDivision of Radio Ilbilad Health3500 North LavaP.O. Box 30035Lansing, MI 48909(517) 335-8190

41$63Y411`:

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Section of Radiation ControlMinnesota Department of HealthP.O. Box 9441717 SE Delaware StreetMinneapolis, MN 55440(612) 623-5348(800) 652.9747

Division of Radiological HealthMississippi Department of HealthP.O. Box 1700Jackson, MS 39125-1703(601) 3546657

Bureau of Radiological HealthMissouri Department of Health1730 E. Elm, P.O. Box 570Jefferson City, MO 65102(800) 669.7236 (Missouri only)

Occupational Health BureauMontana Dept. of Health and EnvironmentalSciencesCogswell Building A113Helena, MT 59620(406) 444.3671

Division of Radiological HealthNebraska Department of Health301 Centennial Mall SouthP.O. Box 95007Lincoln, NE 68509.5007(402) 471-2168

Radiological Health SectionHealth DivisionNevada Department of Human Resources505 East King Street, Room 203Canon City, NV 89710(702) 685-5394

New Hampshire Radiological Health ProgramHealth and Welfare Building6 Hazen DriveConcord, NH 030014527(603) 271.4588

New Jersey Dept. of Environmental Protection380 Scotch Road, CN-411Trenton, NJ 08625(609) 5304030/4001 or (800) 648-0394 (in state)or (201) 879-2062 (Northern NJ Radon FieldOffice)

New Mexico Environmental Improvement Div.Community Services Bureau1190 St. Francis DriveHarold Runnels BuildingSanta Fe, NM 87503(505) 827.2948

Bureau of Environmental Radiation ProtectionNew York State Health Department2 University PlaceAlbany, NY 12203(800) 342-3722 (NY Energy Research atDevelopment Authority)

Radiation Protection SectionNorth Carolina Department of HumanResources701 Barbour Drive'Weigh, NC 27603.2008(919) 733-4283

Division of Environmental EngineeringNorth Dakota Department of Health andConsolidated LaboratoryMissouri Office Building1200 Missouri Avenue, Room 304P.O. Box 5520Bismarck, ND 58502-5520(701) 224.2348

Radiological Health ProgramOhio Department of Health1224 Kinnear Road, Suite 120Columbus, OH 43212(614) 644-2727 or(800) 523-4439 (lima only)

Radiation awl Spill limrds ServiceOklahoma State Department of HealthP.O. Box 53551Oklahoma City, OK 73142(405) 271-5221

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Oregon State Health Department1400 S.W. 5th AvenuePortland, OR 97201(503) 2295797

Bureau of Radiation ProtectionPennsylvania Department of EnvironmentalResourcesP.O. Box 2063Harrisburg, PA 17120(717) 787.2480 or(800) 237.2366 (in state only)

Puerto Rico Radiological Health DivisionG.P.O. Call Box 70184Rio Piedras, PR 00936(809) 767-3563

Division of Occupational Health and RadiationControlRhode Island Department of Health206 Cannon Building75 Davis StreetProvidence, RI 02908(401) 277.2438

Bureau of Radiological HealthSouth Carolina Department of Health andEnvironmental Control2600 Bull StreetColumbia, SC 29201(803) 734-470014631

Office of Alt Quality and Solid WasteSouth Dakota Department of Water andNatural ResourcesJoe Foss Building, Room 41653 E. CapitalPierre, SD 57501.3181(605) 773.3153

Division of Air Pollution ControlCustom House701 BroadwayNashville, TN 37219-5403(615) 741.4634

Bureau of Radiation ControlTams Department of Health1100 West 49th StreetAustin, TX 767564189(512) E35 -7000

Division of Environmental HealthBureau of Radiation Control288 North 14E0 WonP.O. Box 16690Salt Lake City, UT 84116.0690(801) 538.6734

Division of Occupational and RadiologicalHealthVermont Department of HealthAdministration Building10 Baldwin StreetMontpelier, VT 05602(802) 828.2886

Bureau of Radiological HealthDepartment of Health109 Governor StreetRichmond, VA 23219(804) 786.5932 or(800) 468-0318 (in state)

Environmental Protection SectionWashington OM* of Radiation ProtectionThurston Airdustrial CenterBuilding 5, LE-13Olympia, WA 98504(206) 753-5962Radon Hotline (800) 3234727

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Industrial Hygiene DivisionWest Virginia Department of Health151 11th AvenueSouth Charleston, WV 25303(304) 348-3526/3427(800) 922.1255

Division of HealthSection of Radiation ProtectionWisconsin Department of Health and SocialServices5708 Odaca RoadMadison, WI 53719(608) 273.6421

Radiological Health ServicesWyoming Department of Health and SocialServicesHathymy Building, 4th FloorCheyenne, WY 82002-0710(307) 777.7956

C.2 EPA REGIONAL OFFICES

&Au Mitasatashat1

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U.S. Environmental Protection AgencyAPT-2311John F. Kennedy Federal BuildingBoston, MA 02003(617) 565-3234

U.S. Environmental Protection Agency2AWM;RAD26 Federal PlazaNew York. NY 10278(212) 264-4418

U.S. Environmental Protection Agency3AM12841 Chestnut StreetPhiladelphia, PA 19107(215) 5974320

U.S. Environmental Protection Agency345 Court land Street, N.E.Atlanta, OA 30365(404)347-3907

U.S. Environmental Protection Agency5AR-26230 South Dearborn StreetChicago, IL 60604(800) 572-2515 (Mina's)(800) 6214431 (other states in region)

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States in Region

Connecticut, Maine, Massachusetts.New Hampshire, Rhode Island,Vermont

New Jersey, New York, Puerto Rico.Virgin Islands

Delaware, District of Columbia,Maryland, pennsylvanis, Virginia,West Virginia

Alabama, Florida, Georgia, Kentucky,Mississippi, North Carolina, SouthCarolina, Tennessee

Illinois, Indiana, Michigan,Minnesota, Ohio, Wisconsin

U.S. Environmental Protection Agency6TAS1445 Ross AvenueDallas, TX 75202.2733(214) 655.7208

Arkansas, Louisiana, New Mexico,Oklahoma, Texas

7 U.S. Environmental Protection Agency Iowa, Kansas, Missouri, Nebraska

726 Minnesota AvenueKansas City, KS 66101(913) 2362893

S U.S. Environmental Protection Agency Colorado, Montana, North Dakota.

8HWM-RP South Dakota, Utah, Wyoming

999 18th Street, Suite 500Denver, CO 80202.2405(303) 293.1709

9 U.S. Environmental Protection Agency American Samoa, Astons, California.

A-1.1 Guam, Hawaii, Nevada

215 Fremont StreetSan Francisco, CA 94105(415) 9744378

10 U. S. Environmental Protection Agency Alaska, Idaho, Oregon, Washington

AT-0821200 Sixth AvenueSwam, WA 98101(706) 442.7660

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