ASSOCIATED RADON SERVICES  a  subsidiary of:

AMERICAN TECHNICAL SERVICES  GROUP, Inc.

5136 SE Orange St.

Stuart, FL  34997

phone 772-219-4334  fax 772-287-1341

email  Kieron Levy, Radon Measurement Specialist internet   http://www.associatedradonservices.com

REPORT OF FINDINGS
RADON SOIL GAS EVALUATION,  GAMMA LEVEL SCREENING & RADIUM-226 SOIL SAMPLE COLLECTION & ANALYSIS
October , 2006
         18 Acre Proposed Apartment Development Site,  Polk County  FL               

SOIL  RADON GAS

A radon gas in soil screening test was conducted on October 16 & 17, 2006  at the above noted uncleared development property using a 24" soil probe and Niton Rad 7 and or William Johnson radon measurement instruments. There is no existing EPA or Florida DOH protocol for radon soil gas testing at this time, and the correlation to indoor radon levels in a completed building is not completely understood. The scope of these investigative services was limited to 2 days on-site data collection.

The un-cleared building site was tested at 15 test  points located  by pacing and reference to  existing soil boring stakes by others.   No horizontal survey control was provided or used and the location of the test point was estimated as representative relative to the supplied site plan. All radon soil gas test locations had normal to dry soil water saturation and the 24" probe was  able to be driven to full  penetration for all measurements. The results, contained in appendix I,  indicate radon soil gas levels that are not uniform with  wide variations from  27 pCi/l @ lake 5 location 1  to  179 pCi/l @ the building # 1 pad location. These radon soil gas levels are considered as moderate to high in relation to other areas of known elevated indoor radon levels in apartments constructed without radon resistant or radon reduction features or prior to radon reduction.

The dry soil conditions at the time of this investigation indicate good radon transport and possible radon soil gas dilution at the soil probe point depths. The underlying dense clay containing strata or any high lower level soil moisture content may also have a tendency to reduce the surface soil radon measurements taken by blocking the inter-granular soil transport of radon gas from strata at lower levels.

GAMMA SCREENING

A gross gamma radiation level screening at all test locations and several estimated building pad locations was conducted using a Ludlam surveyor R3 and model 44-10 2" Nal low level detector. Levels measured ranged from 6.0 µR to 7.5 µR which is at or just slightly above background. The gamma levels were scanned while walking the site with only unexpected minor variations observed.

RADIUM-226  SOIL SAMPLE ANALYSIS

26 hand augured soil samples were collected at radon soil gas test locations and other building pad locations for radium-226 analysis by Environmental Radiological Group Laboratory.

The analysis results for the collected samples are contained in Appendix I & II. There is expected wide variation and  only partial correlation with the measured radon soil gas levels at the same locations. There are no sample measurements in the Homesite Restricted (HR) classification noted below, however Lake 2  at 6’ is 4.79 pCi/g. 12 of the samples were in the Potential Resource (PR) classification.

The following guidelines are based on early research and work by Dr. E Bolch, and others at the University of Florida and EPA funded studies administered by Florida Department of Community Affairs in 1991. (see Appendix III for background & history)
Summary of Fill Materials Management Guidelines ( by others)

Restricted Use (RU): Materials exceeding 11 pCi/g radium.  Should not be used near the surface. Very high potential for elevated radon levels over such materials. Also concern for potential elevated exterior gamma radiation levels.

Homesite Restricted (HR): Materials exceeding 5 pCi/g radium. High potential for elevated indoor radon levels over such materials.

Potential Resource (PR): Materials exceeding 2 pCi/g but less than the HR levels of 5 pCi/g. Moderate potential for radon naturally in the first 10 feet of earth. Can be utilized as fill if diluted with low activity overburden to a level below 2.0 pCi/g radium.

Fill Material (FM): Fill materials imported from off site that are to be placed under any building shall have a radium concentration of less than 2 pCi/g.

Average Baseline (AB): Any near surface strata ( from 0 to 10 ft )with a weighted average radium concentration of between 1.0 and 0.44 pCi/g.

SOIL SURFACE RADON FLUX

The net radon flux for a given area of  soil surface was measured in 4 locations using calibrated E-Perm “H” chambers. These measurements represent the radon gas available at the soil surface per unit area per unit of time, about 20 hours in this investigation that utilized a Rad-Elec H E-Perm propriety test method..

Soil Surface Radon Flux

At this time there is no comparison data available for radon flux from soil measurements and indoor radon levels in a finished building.

CONCLUSIONS

Based upon the radon soil gas measurement results and radium 226 levels measured  this building site does exhibit a moderate to high potential for elevated levels of radon in buildings built according to normal good construction practices.

We recommend that Radon resistant construction features and a radon mitigation system installation be incorporated into the apartment building designs.

Fill material from the Lake 3 location below 3’ depths should not be used directly on building pads.  Only 1 soil sample was taken from 10’ depth, if fill material is to be taken from below the 6’ depth sampled further investigation may be considered.
 
We always recommend that indoor radon screening tests be performed when a new building is completed and prior to occupancy.

Field testing and sample collection was conducted  by  K. M. Levy, FL DOH Certified Radon Measurement Technician for  Associated Radon Services, 
 
William Levy, President
NRPP Listed and Approved Radon Measurement Specialist

Florida DOH Certified Radon Specialist

APPENDIX  I  DATA

 Radon Soil Gas Soil Radium-226 Investigations at  Pollk   County FL Apartment 20 Acre, by: Associated Radon Services

APPENDIX  II  DATA

APPENDIX III ( by others )

Materials Management Guidelines Background & History

Since 1975, the State of Florida has considered the problem of radon in private homes, schools, and other buildings.  There has been a long series of draft building codes, proposed land use restrictions, draft guidelines, draft standards, recommendations, research reports, state-wide surveys, regional and county surveys, and local agency proposals of codes, restrictions and standards.  Millions of dollars have been expended addressing this problem.  Much has been learned and the public has benefited from those expenditures.  Three main areas have received considerable attention: (1) prescriptive methods and materials necessary to construct a home with the maximum degree of radon resistance by the foundation and construction components; (2) designs and operational parameters for sub-slab depressurization systems; and (3) investigations and surveys of various types that clearly indicate that there are rather limited areas of Florida that require full radon protection expense at the construction stage.

On November 15, 1991 the Department of Community Affairs (DCA) published in the Florida Administrative Weekly proposed Rule 9B-51.001 through 52.004 which would incorporate the "Florida Standard for Radon Resistant Building Construction", into the Florida Administrative Code.  On the 29th of May 1992 the State of Florida, Division of Administrative Hearings declared the proposed rule invalid.  There were various aspects of the proposed "radon standard" that were found to be inconsistent with other State of Florida rules and standards.  In addition the Hearing Officer recognized that "there are areas of low radon potential as well as high radon potential in the State and … delineation of these low and high areas can be achieved based on geography and geology.  "The DCA"standard" would have required statewide application without provisions for variances for a low radon potential area that would not require the added expense of the prescriptive building codes and sub-slab depressurization systems.

In late March, 1994 DCA began to circulate for technical review a new draft entitled "Florida Standard for Radon-Resistant New Residential Building Construction."  This draft contains discussion of the new radon potential map being developed for the state, passive radon control techniques, and active radon control systems.  The first site specific measurement mentioned is a soil radium profile, but there are serious questions about the total effort in Section 602.  It does not, for example, address any excavation or earth moving on the site.

On March 21, 1994, the Environmental Protection Agency published "Model Standards and Techniques for Control of New Residential Buildings" in the Federal Register (Vol 59, No. 54, 13402-13416).  The rule addresses the EPA's Map of Radon Potential Zones and "unique radon potential that may exist in their local building areas."  Radium profiles are a prime indication of any "unique radon potentials."

In the Fall of 1994, DCA refocused much of its resources from single family homes to large buildings. The key research areas of importance for the large buildings have now been funded, but results are just beginning to become available.  Several demonstration projects are underway.  Some of the major passive construction techniques certainly apply to the foundations of larger buildings and there appears to be a higher potential for slab penetrations and joints that need to be sealed against radon transport.  Radium profiles before initial planning will be extremely important as excavations and below-surface structures are more common for the larger buildings.  At this time, it appears that the same indoor standards will be applied regardless of occupancy factors.

It is clear that some lands in Florida may require the maximum effort of radon resistant construction currently known as well as pre-construction installation of sub-slab systems.  It is also clear that land destined for development need to be evaluated at the earliest possible stage to determine if they have low, medium or high potentials for radon transport.  The intent of this type of investigation is to provide such decisions.  For those potential developments that plan earth moving for drainage retention basins; for first floor flood protection; for the creation of lakes and aesthetic contours; or for amenities such as golf courses and clubhouses, early knowledge of the radon potentials materials is an invaluable first line defense against future indoor radon problems.  The investigation described in this report provides such a defense and has proven to greatly reduce the indoor radon of the final developments.

Basically, the procedure is to simply add radium 226 (the source of radon) analyses to the valuable geotechnical investigations performed for a potential development site.  One addition parameter, after the expense of core drilling and interpretation, is a small added expense that provides an extremely important data set that can be used for engineering decisions well before the first ground is broken.

Developers, financing institutions, political units, zoning agencies, builders and potential homeowners need specific guidelines to apply to generated radium profiles.  One set of materials guidelines was developed by Dr. Bolch for presentation to Sarasota County in 1985.  The central question at that time was the eventual placement of materials excavated from artificial lakes.  Since radium concentrations often increase with depth, at what concentrations should there be changes in the management of this excavated fill?

Radium concentrations in excess of 11 pCi/g are certainly not acceptable fill where occupied structures will be constructed.  Since significant radon can migrate at least six feet, it is unwise to attempt to cover 11 pCi/g or higher activity materials with lower activity fill at potential home site pads.  In addition, surface materials with a 11 pCi/g or greater radium concentrations yield a measurable increment of external gamma radiation exposure to persons walking, playing or sitting over these materials.  For all these reasons, a material management guideline be considered for strata with radium in excess of 11 pCi/g as Restricted Use (RU).  Depending upon the site plan, recommendations for these materials include (a) restrictions against excavation, (b) reburial with low activity cover at non‑residential sites, (c) use as road base for paved and permanent roads, or (d) other case‑by‑case recommendations.

If the radium concentrations in a depth range exceed 5 pCi/g but are less than 11 pCi/g then this strata is still not acceptable for home sites or occupied structures.  There is, however, little radiological (external gamma) concern over its near surface placement in other areas.  For these reasons, the materials management guideline for strata having radium levels between 5 and 11 pCi/g became Homesite Restricted (HR).  If these materials were excavated, there would be no restrictions upon their direct use on golf courses, greenspace, berms, unpaved roads or trails, parks, or other areas where structures would not be placed directly over this source material.

No structure will have an indoor radon of zero, primarily because no soil or near‑surface strata will have a zero concentration of radium.  Thus, there is no baseline or cutoff concentration of radium.  A good comparative landmark is the "average" soil radium that is associated with the "average" indoor radon concentration.  The data is, of course, from existing homes and are not impacted by the new guidelines, codes, experience, or awareness.  The geometric mean indoor radon level in Florida is very near 1 pCi/l with different data sets producing values just above and just below that level.  The data sets are geometric means rather than simple averages.

The soil radium level associated with the indoor radon level of 1 pCi/l is somewhat more difficult to present, since concentrations change with each depth and some six to ten feet of strata may significantly contribute to radon influx to a structure.  One landmark, the normal surface soil (generally 0 ‑ 1 ft.) radium content in Florida is about 0.4 pCi/g (again a geometric mean).  Another landmark, is the Effective Radium Concentration (ERC) which attempts to express a complex radium depth profile in a single number related to the profile's contribution to radon flux at the surface.  A geometric mean ERC value for Florida is just above 1 pCi/g.

To put this discussion into a simple materials management format consider a materials classification labeled Average Baseline (AB) as being any near surface average radium of 0.44 to 1 pCi/g.  Any tract of land with this level of near‑surface radium would be expected to yield a near average or below indoor radon concentration in homes constructed over this strata.

As the radium level in near surface materials increases so also does the potential for increased indoor radon levels.  However, with current building practices and attention to eliminating penetrations, it should be possible to build upon lands having radium concentrations above this AB category.  One of the early proposed State radon resistant building code drafts limited offsite Fill Material (FM) to a radium concentration of 2 pCi/g or less.  The 1994 draft mentioned in the opening section above suggests that fill material be limited to 1 pCi/g or less.  This is a severe limitation and the authors believe that radon potential calculations for small layers of material less than 2 pCi/g will not exceed the naturally existing profiles that contain such levels.  The materials management recommendations of the authors will remain essentially the same, with some additional caution remarks when appropriate.

The following recommendations made by the authors has essentially been the same since 1985.  Radium profiles normally begin at levels less than 1 pCi/g at the surface and increase with depth, sometimes rather slowly and sometimes dramatically.  The materials management reports by this group have recommended that when lakes and DRAs are excavated, the mixed stockpile of materials from the surface down to the level at which the HR (5 pCi/g) strata is first encountered be considered separately.  At no time have the authors recommended building directly upon 5 pCi/g materials.  Mixed stockpile materials can be traced to their destination by manifest systems and tracked with properly calibrated (microR) gamma survey meters.

It now seems appropriate to recommend that strata falling between the HR and the FM criteria be assigned a separate title.  Materials between 2.0 and 5.0 pCi/g of  Radium 226 have an elevated radon potential, but have some development value as fill IF diluted with sufficient overburden to create a mixed stockpile of a lower concentration.  These strata are normally buried and only become of concern when excavated for the creation of lakes or drainage retention areas.  The strata having radium between 2.0 and 5.0 pCi/g will be categorized as Potential Resource (PR).  These materials are not suitable for direct use at house pads and should only be considered for excavations when the overburden plus the PR material have a predicted concentration of less than 2.0 pCi/g.  Mixed stockpiles should undergo some Quality Assurance testing before final placement.  This can be either random re-sampling or a (microR) gamma survey calibrated against surface radium concentration.  Any published local or state guideline or standard for fill material should be addressed before consideration of excavation and use of PR materials.