Q. How can I contact the manufacturer of the Envirol quick test kits?
A. It appears that Envirol is out of business, or bought by another company. However, information on a number of their kits is now available from SDI (for example, as "SDI Quick Tests"). A contact at SDI is Karen Peluso at 315-699-5526 or 315-727-4064 (mobile).

Q. Names of companies providing field XRF services.
A. Information of various XRF vendors already is posted on this web site. Please go to X-Ray Fluorescence then "Vendor/Instrument Information."

Q. Do you know why LIF and ROST are less expensive than MIP? Is it the longevity of the probe itself? It is just hard for me to conceptualize because the LIF systems are only found on CPT rigs that are much larger and less mobile than the hammer rigs MIPs are found on.
A. In many or most cases, LIF or ROST is more cost effective than MIP. However, they both have very different applications and either could be more cost effective for a particular project. For heavier TPH constituents, PAH compounds, and NAPLs, the LIF or ROST is the preferred option. In contrast, MIP can only detect volatile compounds, but is effective for a broader range of contaminant classes than LIF or ROST. BTEX and halogenated solvents are important contaminant classes where MIP is effective while LIF/ROST is not. In addition, whereas LIF and ROST are preferred for detecting NAPLs, MIP is more effective for detecting lower concentrations of contaminants dispersed in soil and groundwater.

MIPs are still generally deployed from smaller direct push rigs (for example, rotary hammer platforms) that have a high relative level of mobility and are less expsensive to operate. However, LIF or ROST deployed from a heavier CPT rig would be able to achieve greater push depths than a rotary hammer MIP and this can provide better coverage in sites with deep contamination or DNAPLs. Even this generalization may be too broad as many vendors, like Veronex, are making MIP available on larger rigs.

In short, whether LIF or MIP is more cost effective depends on your specific project needs. It is also important to realize that data generated from LIF/ROST and MIP are semiquantitative and, therefore, have limitations. Quantitation of individual compounds of concern usually requires supplemental data (for example, discrete samples submitted for offsite or on-site analysis using GC or GC/MS).

Q. I am searching for a field screening technique to determine the presence of arsenic in soils. Are there any existing technologies/protocols to achieve +/- results in the field, perhaps colormetric?
A. We are not aware of colorimetric techniques for arsenic that have achieved wide use, particularly in soil. X-ray fluorescence (XRF) is likely your best option, without knowing more about your site. Use of XRF on undisturbed, in-place soil would give you qualitative to semiquantitative data, whereas actually collecting a sample and homogenizing it (say, in a sandwich bag or other plastic bag) before analysis may yield semi-quantitative to quantitative data. Other sample processing steps (for example, sieving, grinding, drying) could further improve data quality.

Lead is a potential interferent for arsenic analysis by XRF which, if present at the site, would need to be compensated for in the XRF method--a vendor can help with this. Also, optimal reporting limits for arsenic by XRF are in the 40-60 mg/kg range and are very matrix-specific. Actual reporting limits attained for a given project may be considerably higher. Actual sensitivity, as well as other aspects of method performance (precision and accuracy), should be evaluated for a specific project through initial "pilot testing" of the method and assessed relative to project action levels and data quality objectives.

Q. I have a site with lead impacted soils. We have been directed by the MPCA to excavate, stablilize (when exceedance of TCLP) and haul. My question is, is there a field TCLP analysis that can be used to facilite the excavation? My concern is that the 16 hours required for TCLP would slow the whole process down.
A.To the best of our knowledge, there is no way around the TCLP extraction time. The problem is not from the lead analysis but rather the TCLP extraction that simulates leaching in acidic conditions. A weak acid (Acetic acid) is added to a weighed sample and the solid sample is spun for 18 + 2 hours in an appropriate container (depending on the analyses proposed on the extract). The 18-hour spin time is crucial to the extraction and can't be avoided.

A question we would pose is why not use x-ray flourescence (XRF) to guide excavation in near real-time and then segregate waste piles based on the "20 times rule." The "20 times rule" is a way to correlate a totals concentration with a worst-case TCLP concentration. A description is attached. The 20 times rule concentration for lead is 100 mg/kg, where the total lead concentration is 20 times the TCLP limit of 5 mg/L. Use of this could expedite the excavation.

If lead is the only TCLP constituent of concern and the form is consistent (an oxide, metallic, other) it could be possible to make a correlation between XRF and a technology such as graphite furnace atomic absorption (GFAA) spectroscopty or fixed lab analyses. However, under most circumstances lead comes in many different forms and abundances, and making a sound correlation between total XRF or fix lab GFAA analyses will not work. We would suggest that excavation be guided by XRF and then the material stockpiled on site and segregated to the degree possible based on concentration. If the total metals concentration does not exceed the 20 times rule (100 mg/kg) then further characterization is not necessary. If the waste exceeds the 20 times rule by several orders of magnitude (>10,000 mg/kg) then TCLP would once again not be required because TCLP results would exceed the TCLP limit of 5 mg/L and the soil would be simply disposed of as a hazardous waste. For the soil with concentrations above the 20 times rule, but less than two orders of magnitude above the 20 times rule, the material should be stock piled and a single 5to 10 point composite collected and analyzed for TCLP lead. You can bring TCLP instrumentation to the field for lead and it can work effectively, but only if there are not any other constituents of concern because bringing ICAP to the field is not yet practicable.

To provide you with the best guidance, we really need more information about conditions at the site. For example,

(1) What is the action level for lead at the site? We need to know this because if the site action level is 400 ppm then all excavated soils will likely fail TCLP. If the site action level is 40 then soil removed will likely have TCLP values that both pass and fail. In this case we would recommend pile segregation and TCLP analyses.

(2) How is the excavation efficiency being monitored? (for example, using a fixed laboratory, GFAA or ICAP, Field XRF and so forth). We need to know what analytical methods are being employed at the site so we can recommend a comprable approach or at least a method that can be used collaboratively with existing results.

(3) What are the requirements for disposal of lead? We need to know the disposal requirments so we can determine the effectiveness of the TCLP 20 times rule discussed above.

Q. On a project I am working on, a community group has asked me to answer two questions. First, whether there is a continuous air monitoring system that can speciate VOCs, and whether there is a continuous air monitoring system for total VOCs. I am hoping that some one might be able to provide an answer. We have a problem with TCE in an area, and so far, all of the work is focused on grab samples using SUMMA canisters. Every so often we get a high reading of TCE. We want to know whether there's another method for monitoring on a continuous basis. Also, the monitor has to be pretty sensitive, as the Region IX provisional PRG for TCE is between 1.7 - 0.017 ppbv. If there is any information you have, it would be much appreciated. Thanks very much.
A. In answer to your first question (speciation of VOCs), Fourier Transform Infrared Spectoscopy (FTIR) technologies could be used to address the issues at your site. I have attached a list of potential FTIR technology vendors and suggest you contact them directly to get specific answers on the perfomance of the various types of available equipment. FTIR has low reporting limits in the parts per billion by volume (ppbv) range, and can speciate a broad range of VOCs. Unfortunately, FTIR is still somewhat challenging and expensive to apply in the field. In addition, useful information on FTIR and other "open path" air monitoring technologies can be found at cluin.org/programs/21m2.

Portable gas chromatographs (GC) may also be useful for VOC speciation at your site. A number of companies market portable units with air pumps and pre-concentrators that can be used for continuous ambient air monitoring. Examples are the Scentograph sold by Inficon and the FM2000 sold by O.I. Analytical. Their company websites are www.hapsite.com and www.oico.com. With pre-concentrators and a range of sensitive detectors, these units can measure a broad range of VOCs and acheive reporting limits in the ppbv range. In addition, there are some new sensor technologies emerging, but these are still experimental and not widely available.

In answer to your second question, a broad range of continuous monitoring equipment is available that can report concentrations of total VOCs. Examples include personal health and safety monitors that are based on photoionization detectors (PIDs) and flame ionization detectors (FIDs); refer to a safety supply house for additional information. However, such systems may not be sensitive enough or respond to a broad enough range of VOCs to meet your needs. For example, many total VOC meters respond well to hydrocarbons, such as benzene, but less well to halogenated solvents such as TCE. Thus, the technologies noted above that can speciate VOCs at low concentrations may also be your best bet to report total VOC concentrations of concern for your site.

Q. In your training module: Inorganic Chemical Characterization Techniques ... slide MV-7 you state "carbon monoxide and sulfur compounds ... pass directly through the units internal filters ... " Can you provide a reference that will substantiate this claim? It is contrary to my experience, and I would like to clear this up.
A. We have contacted several vendors of mercury vapor analyzers (MVA) regarding the instruments' sensitivity to carbon monoxide and sulfur compounds. Based on the most current information we collected, it appears that carbon monoxide has no effect as an interference and gaseous sulfur compounds generally have no effect. Sulfur dioxide (SO₂), aromatic organics, and other organics such as acetone may cause potential interferences, but must be present in extremely high concentrations to saturate the instrument before you can see a noticable effect. Sulfur particulates that can pass through internal filters (for example, 0.2 microns) can cause interferences by depositing on internal sample lines and scavenging mercury. Some instruments allow for the filters to be analyzed and any interferences can be subtracted from detected mercury concentrations. However, given the types of applications in the environmental industry (ambient air monitoring), it is highly unlikely that today's instruments will have problems with interferences. The slide from which you pulled this information is from training developed in May 2002. Since then, this information has been updated.

Q. What percentage of metals in dirt and or water constitutes it as a hazardous waste?
A. The percentage of a metal in a soil does not determine if it is a hazardous waste under the Resource Conservation and Recovery Act (RCRA). A soil or liquid is classified as a hazardous waste under RCRA if the concentration measured in a weak acid extract of the soil or water exceeds the regulatory threshold limit values provided in 40 CFR part 261.24. US EPA method 1311, which can be downloaded at the following web address http://www.epa.gov/epaoswer/hazwaste/test/pdfs/1311.pdf is used to prepare the extract from a soil or water sample. The method is equally applicable to waters or multiphasic liquids. The regulatory threshold limit values are provided as a liquid concentrations and can be found at 40 CFR 261.24. You can calculate a conservative estimate of when a total metals concentratration for a water or soil is likely to exceed the specified TCLP threshold limit values by dividing the concentration measured by 20 and comparing that concentration to the threshold limit values. If the concentration does not exceed the threshold limit value then doing a TCLP test is not required. If it does then you may need to do the test to make sure the extract will exceed. The twenty times rule is just based on complete extraction of all contaminants and is therefore very conservative, actual leachability will likely be much lower depending on the mineral species present.
For more information you can download the final TCLP rule by going to http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=10003POD.txt pressing "control F" and searching for document number oswfr89026.

Q. I have been trying to access the "hot Topic" hotlink to the http://www.frtr.gov; the federal remediation treatment roundtable matrix. It has not been accessible for 2 days now- is it no longer supported, or is the site down? Do you know who a POC for that site would be?
A. I was able to access the FRTR web site; however, I noticed that I had to type the "www..." portion of the address for the site to load (in addition to the ...frtr.gov portion of the address).

Q. Do you know of anyone who is familiar with using a forensic investigation to conduct isotopic analysis of TCE? The concept is to differentiate between two TCE sources in ground water based on a "fingerprint" of their isotopes. We have a site in Minnesota that we are considering using this type of analysis on.
A. The isotopes of chlorine fractionate poorly over a very narrow range. Carbon, on the other hand, has a good deal of fractionation over a broader range. End member product isotope ratios will need to be established to determine if the technique will be viable. There are numerous consulting firms in addition to EPA's Brownfield Technical Support Center (BrownfieldsTSC.org) which specialize in forensics. Geomega (Andy Davis, 303-443-9117) http://www.geomega.com/contact.htm and Ian Kaplan's firm, which is associated with UCLA. Randy Basset, formally with the U of A. and the staff at the University of Texas. Bruce Darling with LBG Guyton and associates guytonl@bellsouth.net. Another useful resource can be found at http://www.zymaxforensics.com/.

Q. Hi, I am interested to know what would be the accuracy on determination of Ca in cement by XRF (Philips 2404 WD). We intend to use pressed powder pellets. Is this the best sample preparation method? What should be done to achieve accurate results?
A. We have contacted the German laboratory that manufactures the instrument you will be using to run your analysis, but have not been successful in connecting with them. Our recommendation is that you continue to attempt to contact this laboratory concerning their default laboratory precision and bias numbers for the method and instrument to be used. This is the normal initial step in identifying the potential limits on accuracy, which can be expected and the adequacy of the measurement for the intended use. These default limits are generally based on the analysis of standards or a Compton scattering calibration. Regardless of the calibration used, the point in finding out what the initial instrumental performance limits are is to begin to evaluate if the total uncertainty associated with a measurement is too great such that the data cannot be reliably used for the intended purpose or decision.

Total measurement variability (bias and precision = accuracy) will determine the accuracy of a measurement. To more fully understand the expected variability in results from the true state, standard statistical methods should be used to analyze the variability/uncertainty associated with any set of measurements as the data is collected or early in the data collection process. A demonstration of methods applicability should be considered where two comparable methods for analysis are used to arrive at information, in this case CA concentrations in concrete. Results can then be compared to further understand or identify any potential bias created by the sampling process, analytical instrument, or matrix sampled. Total uncertainty can be evaluated by analyzing a series of additive factors, which range from sampling uncertainty through analytical uncertainty. Each of these sources of uncertainty can be measured using specific types of quality control samples, which can be introduced during the sampling and analysis process. William Ingersoll's work can help practitioners begin to learn to quantitate total measurement uncertainties. This type of sophisticated analysis is generally only needed when low-level concentrations are expected and decision criteria are close to the method reporting limits.

With respect to your specific problem, the high concentration of CA can pose some challenges and potential benefits to the overall accuracy of your measurements. At high concentrations, most x-ray fluorescence (XRF) units are accurate to within several percent, which is usually much more than sufficient to support construction materials decision-making. An 55Fe (iron) source for a radioactive source type XRF unit is preferred based on the activation coefficient for CA, but this would limit any trace element capabilities.

Using an X-ray tube instrument, interferences can arise as a function of concentration when K shell configurations overlap. The total chemistry of the material being analyzed will control the need for inter-element corrections and the presence of interferences, an X-ray tube unit would facilitate this type of analysis and you should contact a vendor like Niton or Innov-x for more information on x-ray tube instruments (see table below).

Bottom line, is that you should not have a problem, in our opinion, but without a better understanding of the instrument you are planning to use and the chemistry of the concrete in question we cannot provide any definitive information to you. We suggest you perform a demonstration of methods applicability using a handful of samples and perform analyses using both XRF and inductively coupled argon plasma spectroscopy (ICP) to ensure that the results you are going to obtain will be sufficiently reliable to support decision making. Even in this regard, without knowledge of your decision criteria we cannot be sure that any additional work is required. If default precision and bias are sufficiently low versus expected concentrations and related tolerances to support decision making no action other than tracking results statistically using a probability plot, may be all that is needed (see EPA G-9 for better discussion of the use of probability plots (http://www.epa.gov/quality/qa_docs.html).

Q. Can you please tell me what electromagnetic radiation are used in each of the technologies? e.g gas chromatography- is it infrared?
A. Here are the types of electromagnetic radiation associated with analyte detection for the analytical technologies we have listed:

• XRF -- X-rays
• Test kits (colorimetric and IA) -- UV or visible spectrum
• FOCS -- UV or visible spectrum
• LIF -- UV or visible spectrum
• GFAA -- Visible spectrum
• FTIR -- Infrared (IR)
• GC -- although some detectors use electromagnetic radiation for detection (there are IR and atomic emission detectors, for example), most GC detectors use some form of current for detection (that is, they use an ionization process of some type to set up a measurable electical current). In some cases, however, the ionization source itself is radioactive (e.g., the Nickel-63 beta source used in electron capture detectors).
• Mass Spec -- this again generally uses ionization (along with magnetic fields), as opposed to EM radiation.

Q. Are any innovative technologies for measuring BTEX, MTBE, TBA contamination in shallow soil and wheathered shale bedrock to determine hot spots or contaminant gradient?
A. The best technology for measuring BTEX, MTBE, and TBA in the fields is a gas chromatograph/mass spectrometry (GC/MS) system equipped with a purge and trap sample sparging unit. Portable GC/MS systems, such as the Inficon Hapsite system, can be equipped with a head space sample preparation unit or a purge vessel. The headspace option is less desirable for use because of the relatively high water solubility of MTBE and TBA. Even when a purge vessel is used and MTBE or TBA are primary targets, method performance can be improved by salting the water (usually mixed with soil) before analysis in a purge vessel. This step is performed to improve extraction efficiency and the purge vessel is also often heated to 40 degrees centigrade. A gas chromatographic system can also be used with an optimized extraction system using a purge vessel equipped with a photo ionization detector (PID) or a dual detection system with a flame ionization detector (FID). However, this type of instrument configuration is best used when matrix interferences are known to be minimal, which is rarely the case for most petroleum sites. There are no specific test kits that are available for these analytes specifically.

Q. What are the chemical constituents of diesel fuel? Are PAHs present in diesel or are they products of combustion.
A. Usually diesel fuels are a complex mixture or unsaturated aliphatic and aromatic hydrocarbons. Poly nuclear aromatic hydrocarbons (PAH) are present in most refined hydrocarbon fuels as a result of the cracking process. They are a product of the combustion process, like that used in refining or during the burning of petroleum products. Heavier hydrocarbon fuel products such as jet fuels may have higher contents of PAH as might heavy oils, but the relative concentration of PAHs is also dependant on the cracking process used during refining and the nature of the feed crude being processed. In general, PAHs can make up between 1 and 10 percent of a refined petroleum product with lighter end products having lower relative percentages than heavier end products. Spent or burned hydrocarbonsiduals can have even higher PAH contents.

Q. Trying to locate companies that provide training services on EPA methods such as 625?
A. Try the following web links www.pacslabs.com and www.lab-data.com or also contact a local certified laboratory in your area who has an experienced gas chromatography/mass spectrometer group, they might be willing to show you their lab and discuss their procedures with you. Make sure, regardless of the trainer you select that they depend heavily on the method itself where necessary and do not suggest method modifications, which are not generally accepted or peer reviewed.

Q. What is the PRG for total lead in California?
A. The California PRG for lead is 150 ppm for residential receptors. More information can be obtained at dtsc.ca.gov.

Q. Are there any commercially available field screening methods available for Pesticides? Can they provide economical, real time data that can be used to screen out samples for lab based confirmation?
A. There are numerous commercially available pesticide kits that can be found through several vendors. Strategic Diagnostics is one such vendor. Listed below is a table of methods for which commercially available kits are available.

Immunoassay	SW-846 Method
PCBs	4020
Chlordane	4041
DDT	4042
Toxaphene	4040
PCP	4010

Also look at SW-846 on line for more information at the following website for specific information on methods concerning specific pesticides. The data collected using these methods can be used for many purposes including confirmation with or without fixed lab comparative analyses. The selection of comparative analyses for fixed lab analyses can certainly be facilitated using field test kits, but the decision is usually driven by concentration. It is our opinion that lab-based comparative analyses should be focus in and around decision criteria where there is the highest degree of uncertainty.

Q. To what extent do different soils retain water?
A. Clay soils retain the most water. Sandy soils have the coarsest texture and therefore the largest pore sizes. These large pore sizes are too large to hold water through its cohesive property. Clay soils have the finest texture, therefore the smallest pore sizes. Clay soils are able to hold much more water because of their smaller pore size.

Q. I have a regulatory group that needs a reference to indicate that results from in-situ field methods for analysis of volatile organics in soil and soil gas are frequently higher than those measured from the same media/site in the laboratory. I realize this is common knowledge that sampling and subsampling cause loss but I need a good reference to explain this. I have several of Hewitt's papers.
A. We do not agree that it is necessary common knowledge that in situ measurements are generally biased high relative to fixed laboratory methods when analyzing samples for the presence of volatile organics. Test kits can appear to biased high because they tend to analyze for the presence of several classes of compounds. If several compounds are present then it could appear that a result from the test kit [say for chlorinated volatiles] could appear to be biased high as compared to specific results [for say chlorobenzene]. In terms of soil gas, the comparison between volatile analyses in the lab and soil gas will be likely the opposite. Because concentrations in soil gas are dependant on what can partition from the soil, volatiles remain in place that are stripped during the application of the analytical lab method. Allen Hewitt has documented that significant loss of volatile can be expected in soil samples where the samples are agitated and/or just exposed to a change in atmospheric pressure, however other methods which involve the extraction of sample in the field using methanol can be very effective at minimizing the loss of volatiles during sampling prior to analysis. A bigger question maybe how representative is the sample that is collected and how heterogeneous is the sample that can result in observed differences between volatile analyses regardless of when and where they were performed. Hewitt�s papers are amongst the best published in terms of looking at the impact of sampling methods on the loss of volatiles. However, there are other sources of variance that may also be realized because soil gas is different from purge and trap or extraction methods. You must be careful, for example, when using field based analyses that use similar analytical procedures both in the lab and in the field. If the result obtained in the field is from a head space analyzer, such is commonly used with potable GC/MS methods, the relationship expected is similar to that which might be expected from soil gas (for example, relative to low bias).

Q. Can isotopic methods be used to identify the parent chemical of VOC daughter products (1,1-DCE and vinyl chloride) in cases where these daughters could have resulted from the breakdown of more than one parent (TCE and 1,1,1-TCA)?
A. It is possible to distinguish between isotopes of chlorine in water if sufficient fractionation exists between various parent sources. Ablation in surface soil and other geochemical processes can impact chlorine ratios so we do not suggest attempting soil isotopic analyses. Ratio numbers between various daughter products and parents can also be helpful. For more details concerning isotopic methods and other forensic methods we suggest you go to the following website and journal for more information. http://www.zymaxforensics.com/ and http://www.environmentalforensics.org/journal.htm.

Isotopic fractionation of chlorine is limited in extent even under the best conditions. Chemical fingerprinting and other intrinsic tracers or surrogate compound analyses may be useful for determining the potential for linking contamination to source areas. Are there any other contaminants that might be characteristic of one source area versus the other? These can sometimes be useful.

Q. I am interested in recommendations on field screening of sediments for low levels Naphthalene contamination (~100ppb).
A. There are numerous field screening techniques that can be used to test for the presence of petroleum hydrocarbons and several with the capability to semi-quantitatively or quantitatively identify polynuclear aromatic hydrocarbons in the low part per million (ppm) range in sediment or soil samples. Usability for these kits diminish as detection limits in the mid to low ppb range are required.

One such technology is available at http://www.site-lab.com/ and uses ultraviolet fluorescence (UVF) to quantitatively identify total PAHs. Site lab currently has one UVF detector with the capability to detect total PAHs at 25 ppb and another can detect total PAHs at 50 ppb. The kits require a quick extraction procedure followed by analysis using the UVF detector. Site-specific response factors can be developed based on a preliminary demonstration of methods applicability (DMA) study and responses may then be used to estimate naphthalene concentrations in the low ppb range. A consultation with the manufacturer, completion of a DMA, and development of site specific limits of detection are recommended before attempting to use this technology full scale at your site.

Immunoassay kits can detect PAH compounds in the low ppm range and kits are available from Strategic diagnostics http://www.sdix.com/ can detect carcinogenic PAH compounds in the low ppb range. The naphthalene concentrations required to elicit a response in these carcinogenic immunoassay test kits are unfortunately much higher (30,000 ppb). These tests also lack the specificity to qualitatively identify only naphthalene as they respond to a variety PAH compounds.

One recommendation for your sampling effort would be to evaluate all potential chemicals of concern. Are other PAH or TPH compounds expected in sediment samples? If so, these other indicator compounds can often be used to develop correlations between field test kit concentrations and fixed laboratory results. For an example of how that can accomplished see the Cos Cob Case Study developed by EPA's Brownfield Technical Support Center at http://www.brownfieldstsc.org/pdfs/CosCob-casestudy_Final.pdf. Specifically, you should review the section discussing the DMA and evaluation of PAH and TPH field results.

If quantitative and qualitative results for specifically naphthalene in the low ppb range are truly required for project success then sample analysis by an appropriate EPA SW-846 may be warranted. Method 8270 operated in the selective ion mode can achieve very low ppb level detection limits, method 8310 a high pressure liquid chromatography (HPLC) method designed for analysis of PAH compounds may be suitable to meet project objectives, and finally method 8260 for volatile organic compounds if effective for naphthalene in the low ppb range.

Q. Can GC-MS generally be used to differentiate between types of petroleum based fuel products?
A. In most environmental applications, gas chromatography with a flame ionization detector (GC/FID) is used to evaluate fuel concentrations and comparison with standards (diesel, gasoline, kerosene, jet fuel, motor oil) is used to qualitatively identify the type of petroleum hydrocarbon. Fuel patterns from the sample are visually matched to standards and can be used to identify fuel types in the sample.

GC/MS although a more costly method can also be used to qualitatively and quantitatively evaluate different fuel products see http://www.dpra.com/index.cfm/m/147.

Although this technique is not as commonly used. GC/MS analysis will allow the user to identify different hydrocarbons in a complex fuel mixture.

One suggestion for the use of GC/MS to identify different petroleum based fuel products is to evaluate concentrations of polynuclear aromatic hydrocarbons (PAHs) in the sample. Most fuel types contain varying concentrations and types of PAHs (naphthalene, benzo (a) pyrene, chrysene ect.) and the ratio of these PAHs in a fuel sample can be used to distinquish different fuel types. GC/MS techniques for analysis of PAHs includes EPA SW-846 method 8270 [operation in the selective ion mode (SIM) allows the user to achieve lower detection limits and avoid common interferences].

GC/MS analysis of volatile components of fuels can also assist in differentiating between various fuel types. For example a standard EPA SW-846 Method 8260 m analysis of a fuel or fuel contaminated sample would provide critical information for benzene, toluene, ethylbenzene, and xylene (BTEX) ratios which can be used to identify freshly spilled fuels vs. older spills. Methyl tert butyl ether (MTBE) if identified in a sample using this analysis would also indicate a gasoline fuel type manufactured from the early 1990s to early 2000 (a gasoline additive used during that time period).

If fingerprinting fuel types to determine potentially responsible parties is the goal then several forensic chemistry techniques are also available. See http://www.dpra.com/index.cfm/m/159.

Q. I am trying to measure vapors that might come off free product fuel oil. Is it better to use Summa cannisters for this. Is it OK to use Charcoal tubes to measure TVOC's from this as (#2 fuel oil)?
A. Depending on your data needs both the summa canister and charcoal tubes are effective techniques for evaluating vapors potentially resulting from #2 fuel oil. You need to determine whether you want to evaluate specific volatile compounds or total volatile components and at what concentrations to better assist in choosing potential analytical techniques.

For example a standard EPA SW-846 Method such as method 8260 analysis of the product would provide qualitative and quantitive results in the low part per billion (ppb) range for a number of volatile organic compounds likely found in the fuel. These include benzene, toluene, ethylbenzene, and xylene (BTEX), methyl tert butyl ether, and substituted benzenes such as 1,2,4 and 1,3,5-trimethylbenzene. Specifics of the method can be found at http://www.epa.gov/epaoswer/hazwaste/test/pdfs/8260b.pdf.

An analysis of vapors specifically volatilizing and coming off the fuel (without the benefit of an inert gas purge of the free product as with SW-846 method 8260) should use a summa canister or other air sample collection technique such as tedlar bags. The laboratory would still use a modified SW-846 method 8260 method for analysis such as the TO-14 method performed by air toxics http://www.airtoxics.com/cinfo/solutions.html#8260b. There are also numerous commercial analytical laboratories that provide this type of analysis in your area.

The advantage of the charcoal tubes for analysis is the benefit of real time results, however these technologies tend to provide results with higher detection limits (in the ppm range) and specific ranges of detection (for example 5-15 ppm), provide limited compound specificity (not all compounds available or provide results for compound classes), and are subject to potential interferences. Charcoal tubes are available from manufacturers such as Draeger or distribution companies such as SKC.

In conclusion, charcoal color tubes provide semi-quantitative results in real or near real time and can be configured to detect specific compounds or classes of compounds but are subject to limitations. If you require detection limits in the ppb range and would prefer a definitive method of analysis then GC/MS/FID techniques such as the TO-14 with SW-846 8260 analysis is recommended.

Number 2 fuel oil can also be in a pure state and may not contain many of those compounds detected by the methods noted above. Alternative methods include simulated distillations of isotopic dilution methods such as EPA 600 Series method 1625, when more accurate forensic information is needed. Concentration can also limit the utility of canister and tube methods. Careful testing is needed of any method proposed for use to evaluate the quality of information produced versus the decision requirements. Wothout further information it is difficult to make a project specific recommendation concerning you site unless more is known concerning the decisions you are attempting to make.

Q. I am looking for a reliable field test kit for TCE in soil. Unfortunately, Strategic Designs Inc. no longer carries their soil test kit, only water. Are you aware of another vendor that carries a similar field test kit?
A. You are correct, after speaking with representatives at Strategic Diagnostics, it appears they have discontinued the soil application for the TCE test kit and only produce a kit for TCE in water (See http://www.sdix.com/ProductSpecs.asp?nProductID=22.)

Our search did not identify another vendor producing immunoassay test kits for TCE in soil, however we did identify another field based analytical technology. The L2000DX analyzer provided by Dexsil is capable of providing quantitative analysis or organic chlorine compounds and specifically TCE. The technology converts organically bound chlorine in the soil sample to inorganic chloride and the resulting chloride can be quantified using the L2000DX analyzer. The technology is limited in much the same way as immunoassay techniques that can be subject to cross-reactivity of similar organic chlorine compounds. If other chlorinated solvents, PCBs, or organochlorine pesticides are potentially present in your specific site matrix, the technology cannot qualitatively identify these compounds and they are reported as TCE. If the contaminant is unknown the instrument can be configured to provide a "worst case" scenario for an upper limit concentration of a target compound.

The LD2000DX analyzer costs $3,675 to purchase and test kit materials are also required to complete analyses. Dexsil also provides rentals of the equipment allowing a user to purchase test kit materials only and rent the more costly analyzer. Method detection limits for TCE in a clean soil matrix were reported by the manufacturer at 2ppm and the practical quantitation limit for a similar matrix was reported to be 8 ppm. Actual MDLs and PQLs for application at your site would likely several times higher. Depending on the presence or absence of potential interferences and applicable action levels the technology may provide sufficient sensitivity for application at your site. We recommend a consultation with technical experts at Dexsil and that you conduct a demonstration of method applicability (DMA) study in accordance with the principles of EPA's Triad approach at your site prior to using the technology full scale. Information concerning design of a DMA through review of Triad case studies and profiles can be found at https://triadcentral.clu-in.org/.

Q. Why are ionization interference less severe in ICP than flame emission spectroscopy?
A. Ionization interference is less severe in ICP for several reasons. The plasma spark used in ICP analysis burns much hotter than a flame emission system. The temperature of an ICP flame in the analytical zone is approximately 10,000 degrees C. The higher analysis temperature allows more interfering analytes to be burned away. ICP also uses a magnetic coil to hold the sample in place and this magnetism confines metals in the convection zone (plasma spark) for a longer period of time. The longer resonance time allows complete ionization of the sample thus limiting interference when compared to flame emission.

Q. What is the critical composition of Aromatic compounds (BTEX) in the air to be a main reason for cancer in human body?
A. The critical (and only) component of BTEX that is defined by EPA as a known human carcinogen is benzene. Existing data for the remaining compounds (toluene, ethybenzene, and xylene) do not indicate that these compounds cause cancer in the human body.

The threshold for daily exposure to benzene via inhalation is 3 x 10-2 mg/m3. For additional information concerning chemical compounds and their effects on the human body go to http://www.epa.gov/iris/index.html.

Q. I'd like to know whether UVF, XVF, VIS/NIR, can be used to measure a soil's fertility?
A. Although this question extends beyond our expertise in the environmental characterization and remediation arena we have provided the following suggestions.

Evaluation of soil fertility is complex and involves analysis of a range of macronutrients (nitrogen, phosphorus, potassium, sulfur, calcium, magnesium etc.), micronutrients (boron, chlorine, copper, iron, manganese, molybdenum, zinc) pH, soil composition (sand, silt, clay), cation exchange capacity, and organic material content to name a few. The evaluation is also specific to geographical location and the crop being grown.

Ultraviolet fluorescence (UVF) can be used for analysis of compounds such as nitrogen and sulfur related to soil fertility.

We could not find any references for XVF technology and assume you are referring to x-ray fluorescence (XRF). This technology is ideally suited for analysis of metals in a variety of matrices and specifically soil. Because these analytes are the main nutrients you would be interested in evaluating for an estimation of soil fertility this technology would be useful. Today's XRF analyzers are field portable and can quantitatively and qualitatively identify elements from sodium to uranium making evaluation of micronutrient and macronutrient concentrations easy and in real time. Vendors include Niton, Innov-X, Oxford instruments, and Rigaku, RONTEC, and XCALIBUR to name a few recently evaluated under EPAs Environmental Technology Verificaiton (ETV) program. Visible near infrared (VIS/NIR) spectrophotometers can be used to evaluate some plant and soil characteristics associated with fertility. Portable units are available from vendors such as analytical spectral devices (ASD) that can assist in evaluation of organic carbon, total nitrogen, cation exchange capacity, sand fraction, silt fraction, clay fraction, copper, zinc, chromium, nickel, cadmium, and manganese.

Q. How can I set up an experiment for analyzing hyrdocarbons concentration in concrete?
A. The technique recommended is the same as those currently in use by environmental analytical laboratories. The sample must be physically ground or crushed to a powder to increase the effectiveness of the solvent extraction. From there a method such as EPA SW-846 method 8015B or 8440 is recommended.

Q. Can TCE be fingerprinted to evaluate two different sources when it cannot be done by concentration measurement or variation in groundwater geochemistry?
A. After ruling out evaluation of sources by concentration and groundwater geochemistry you are essentially left with isotope fractionation as the only tool available to potentially differentiate between multiple TCE sources.

You may be able to differentiate sources using isotope fractionation or other forensic chemistry techniques. Forensic chemistry techniques are discussed at http://www.zymaxforensics.com and http://www.environmentaldatapages.com/bmorrep.htm .

Variations in manufacturing processes and source materials that affect carbon and chlorine isotopes have been used to distinguish between different manufacturers. See http://www.science.uottawa.ca/~eih/ch6/6chloro.htm.

Q. How do you prepare 1-benzyl-5-phenylbarbituric acid for FTIR - KBR pellet or something different? Can you send me an FTIR scan of this compound?
A. There are hundreds of libraries that can be accessed through the internet. However many require a membership fee. See http://www.spectroscopynow.com/Spy/basehtml/SpyH/1,1181,3-0-0-0-0-home-0-0,00.html or http://www.acdlabs.com/products/spec_lab/exp_spectra/spec_libraries/fdm_ir.html#organic.

A good resource for available databases can be found at http://www.lohninger.com/spectroscopy/dball.html

Some spectra may be downloaded for free at http://www.aist.go.jp/RIODB/chem.html.

Q. I'm interested in finding an updated field sampling technique and analytical method for the quantification of dissolved gases in groundwater. I'm not sure if something of this nature exists. I am looking for something that gives good quality results but doesn't cost as much as traditional analytical costs for these gases. Any ideas? Thanks for your attention to this matter.
A. There are a variety of traditional analytical methods available for dissolved gases.� Since you have not provided actual gas names for compounds you are interested in we will assume you would like traditional gases such as dissolved oxygen and those applicable to monitored natural attenuation (MNA) projects such as carbon dioxide, methane, ethane, ethene. �

Other compounds of interest can be fuel breakdown products such as acetylene, iso-butane, n-butane, propane, and propene or chlorinated solvent daughter products such as trichloroethene, 1,2 dichloroethene, and vinyl chloride.

Dissolved oxygen can be monitored using field analytical technologies such as a water quality meter provided by YSI www.ysi.com or Horiba http://www.horiba-water.com/am.html, and can also be evaluated using colorimetric test kits such as those provided by Hach http://www.hach.com/.�

Currently there are no colorimetric or other simple field analytical techniques to evaluate dissolved concentrations of carbon dioxide, methane, ethane, ethene.� Field portable gas chromatographs (GC) with electron capture detectors (ECD), photo-ionization detectors (PID), and flame ionization detectors (FID) such as those available from Photovac www.photovac.com and SRI www.srigc.com are available to provide quantification of most dissolved gasses for environmental applications.

Q. What would be the cost effective analytical approach for determining if PAHs in shallow soil samples at a LUST site are associated with fill material or are actually the result of either a release or a spill of diesel fuel?
A. We would suggest the use of GC/MS operated in the selected ion monitoring (SIM) mode to identify the types and concentrations of polynuclear aromatic hydrocarbons (PAH) in the shallow soil and samples associated with the diesel spills.� Most fuel types contain varying concentrations and types of PAHs (naphthalene, benzo (a) pyrene, chrysene) and the ratio of these PAHs in a particular sample can be used to distinguish different fuel types or contaminant sources.� GC/MS techniques for analysis of PAHs includes EPA SW-846 method 8270 http://www.epa.gov/epaoswer/hazwaste/test/8_series.htm [operation in the selective ion mode (SIM) allows the user to achieve lower detection limits and avoid common interferences].

If fingerprinting fuel types to determine potentially responsible parties (PRP) is the goal, then several forensic chemistry techniques are also available (http://www.dpra.com/index.cfm/m/12). Analysis of crude oil and petroleum product fractions using GC/MS has been used by a number of consulting firms and laboratories. The Zymax website http://www.zymaxforensics.com/ has a lot of useful information concerning GC/MS analysis of crude oils and petroleum products for forensic chemistry applications. GC/MS, although a more costly method, can also be used to qualitatively and quantitatively evaluate different fuel products (see http://www.dpra.com/index.cfm/m/147).� Although this technique is not as commonly used, GC/MS analysis will allow the user to identify different hydrocarbons in a complex fuel mixture.

A simple weight of evidence approach can be used to evaluate the likelihood that PAHs in the shallow fill are associated with the diesel release.� A simple procedure outlining this process is as follows.�

1)� Analyze several shallow fill samples and several diesel contaminated soil/ product samples from the site for PAHs.�

2) In accordance with EPA statistical guidance use a proxy value of one half the quantitation limit for any non-detected values

2)� Normalize all results to benzo (A) pyrene or another carcinogenic PAH (that is divide the concentration of each PAH compound in the sample by the concentration of benzo (A) pyrene in that sample to develop PAH ratios rather than use absolute values)

3)� Develop correlations for each shallow subsurface sample vs. each diesel sample using all 16 PAH compounds (normalized to benzo (A) pyrene).� If the correlation coefficients (R²) approach 1 (0.8 or better show a strong correlation), then the materials likely came from a similar process or have a common origin.� Correlation coefficients approaching 0 indicate that the materials are very different in composition and it is very unlikely that they came from a similar process or have a common origin.

4) Finally, you can use bar charts to evaluate similarities in PAH ratios to compare samples from the shallow surface and those from the diesel impacted soil.� If the materials are similar in nature then they will have very similar PAH ratio patterns for each of the 16 individual PAH compounds.� For example two materials with a likely common origin will have naphthalene as the highest concentration, followed by phenanthrene, followed by acenaphthene, and so on and would also have negligible amounts of the same compounds such as dibenzo (A,H) anthracene, benzo (B) fluoranthene, and indeno-(1,2,3-CD) pyrene for example.�

5) Any shallow soil samples with strong correlations to diesel samples and displaying very similar PAH patterns are likely the result of a diesel release and not that of the fill material.

Q. Is there a simple test for lead that can be done in the classroom either colorimetrically or gravimetrically?
A. There are many colorimetric test kits for available for lead; however, the matrix (paint, soil, water, tissue) you are interested in evaluating is unclear. Colorimetric kits that provide non quantitative results (yes/no lead is present) for paint samples include http://www.leadinspector.com, http://www.leadcheck.com/

Colorimetric kits that provide non quantitative results (yes/no lead is present) for water include http://www.watersafetestkits.com/html/drinkingkits.asp

Examples of quantitative gravimetric methods for the analysis of lead in classroom teaching applications can be found at http://chem.lapeer.org/Chem1Docs/LeadAnal.html and http://www.chem.tamu.edu/class/majors/experimentnotefiles/notes18.htm

Q. Method & use of Dr/2400 Spectrophotometer, principal of operation
A. The question concerning Hach�s DR2400 spectrophotometer is unclear.� The DR2400 can be used to provide quantitative analysis for a variety of Hach test kits. We have provided several links below where you can obtain user information, products specifications, procedures, and instrument manuals for the DR2400 115VAC and DR2400 230VAC models.� Or visit www.hach.com for more information.

Hach - DR/2400 Portable Spectrophotometer

Hach - Download Documentation - DR/2400 Portable Spectrophotometer Manuals

Q. In my report I want to use the concerns listed in direct-push ground water samplers under typical uses. Can you please email me the author name of this web site report?
A. The information on the web site comes from a variety of sources and authors. I would suggest citing the web site itself as your source.

Q. Is there any exisiting literature that compares the results of direct-push groundwater sampling (i.e, "hydropunch", with the results from conventional monitoring well groundwater samples?
A. We suggest you review Chapter 5 of EPA's Expedited Site Assessment Tools For Underground Storage Tank Sites: A Guide for Regulators. (EPA 510-B-97-001). March 1997 and the additional references below that have comparison data.

Demonstration/Validation Of Long-Term Monitoring Using Wells Installed
By Direct Push Technologies
Farrington, S.P. (Applied Research Associates Inc., South Royalton, VT); M.L. Gildea; J.D. Shinn.
Report No: AFRL-ML-TY-TR-2003-4533, DTIC: ADA413061, 78 pp, Apr 2003

The objective of this study was to demonstrate that long-term ground-water monitoring results from direct push wells agree with those from conventionally drilled wells, the currently accepted baseline technology. The five field sites represent a variety of geological conditions, as well as a cross-section of regulatory domains (e.g., EPA regions and states). Direct push wells were installed adjacent to and paired with existing conventional wells, drilled via hollow stem anger. The following sites were part of this effort: the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory in Hanover, NH (EPA Region 1); Dover National Test Site at Dover AFB, DE (EPA Region 3); the Naval Facilities Engineering Services Center at Port Hueneme, CA (EPA Region 9); Tyndall AFB, FL (EPA Region 4); and Hanscom AFB, MA (EPA Region 1). Five sampling runs were conducted over a 15-month period at each site. Target ground-water chemical analytes included tetrachloroethene, vinyl chloride, cis-1,2-dichloroethene, trans-1,2-dichloroethene, benzene, toluene, ethylbenzene, o,m-xylene, p-xylene, 1,4-dichlorobenzene, trichloroethane, and MTBE. Available at http://handle.dtic.mil/100.2/ADA413061

Smolley, M. and Kappmeyer, J. (1991), Cone Penetrometer Tests and HydroPunch sampling: A Screening Technique for Plume Definition, Ground Water Monitoring Review, 11(2), 101-106.

Q. Any information on detecting TATB (triaminotrinitrobenzene) in soils? How can it be extracted from soil and soil concentrations measured?
A. There do not appear to be any widely available or well-established methods for TATB; it is not included on most standard target analyte lists for explosives. However, it is very similar in structure to other explosive compounds (for example, 2-amino-4,6-dinitrotoluene) that are analyzed by published methods such as SW-846 Methods 8330 and 8095. Therefore, it seems that the extraction and analysis procedures outlined in these laboratory-based methods could be easily adapted to TATB. The soil extraction procedure used by both of these methods is ultrasonic extraction using acetonitrile as a solvent, followed by filtration and solid-phase extraction. In Method 8330, the extraction procedure is followed by liquid chromatography (LC) analysis, and in Method 8095, by gas chromatography (GC) analysis.

With respect to field-based methods, immunoassay (IA) tests kits such as the RaPID Assay kits available from SDI should be considered. These kits detect explosives as a class of compounds rather than as individual analytes. The RaPID Assay kits in particular show good response to amino-nitro-aromatics such as TATB. A separate soil extraction kit can be purchased for use with the RaPID Assay kit (the extraction involves a brief shake with methanol followed by filtration). We recommend contacting SDI to assess whether they have any data regarding TATB response with their IA or other test kits, and whether such data can be generated quickly for you if you provide them a few samples from your site.

The bottom line is that whether laboratory or field-based methods are of interest, some up-front method evaluation or validation work will be necessary because TATB is a "non-standard" explosive analyte. Extraction conditions (for example, pH) and/or instrument parameters may need to be "tuned" or optimized for the analysis of TATB. The USACE Cold Regions Research and Engineering Laboratory (CRREL) has done extensive work with explosive analytes and methods. They have identified a broad range of field-based extraction and analytical technologies (from mobile GCs to indicator papers to ion mobility spectometers) that may be of interest to you. Examples of their work are available at http://handle.dtic.mil/100.2/ADA413061.

• http://www.dtic.mil/dtic/tr/fulltext/u2/a351073.pdf and at
• http://www.clu-in.org/conf/tio/explosives_082801/prez/aug01BW.pdf.
• I would suggest contacting Dr. Tom Jenkins at CRREL for more information (603-646-4385 or tjenkins@crrel.usace.army.mil).

Q. Can I find (and where) the explosives absorption spectra in IR that are free to use in science goals?
A. There are hundreds of libraries that can be accessed through the internet. However many require a membership fee. http://www.spectroscopynow.com/Spy/basehtml/SpyH/1,1181,3-0-0-0-0-home-0-0,00.html

A good resource for available databases can be found at http://infrared.als.lbl.gov/FTIRinfo.html or http://www.lohninger.com/spectroscopy/dball.html

Some spectra may be downloaded for free at http://www.aist.go.jp/RIODB/chem.html

Q. I am doing research in the field of Archeology. I am going to detect the underground ancient monuments by using RADAR Satellite Images. So I like to know, what are the costs of RADAR imagers (do not need latest imagers)? Imagers should cover Sri Lanka. What are the resolutions of those that you have? I want to get another RADAR equipment called Ground Penetration Radar (GPR). So I want to know, what are the cost ranges (Maximum and Minimum)? If you can, please send me information regarding this type of research, which has already been completed in certain areas of the world.
A. Here are 5 links to manufacturers and vendors for rental of ground penetrating radar (GPR) equipment and the "geophysical society."

•  MALÅ GeoScience - Manufacturer and vendor/rentals
  
•  Geophysical Survey Systems, Inc. - Manufacturer and rentals
  
•  Sensors & Software Inc. - Manufacturer and vendor/rentals Canada
  
•  Exploration Instruments LLC - rentals
  
•  Association Environmental and Engineering Geophysical Society

Q. Kindly inform me the address of some of the institutes where I can have training in GPR.
A. EPA's Office of Superfund Remediation and Technology Innovation (OSRTI) offers a variety of training opportunities, including a classroom-based training course on field-based technologies (see www.trainex.org for current offerings). The training typically is offered throughout the year at locations within the continental United States. The training devotes about half of a day to field-based geophysical technologies, including ground penetrating radar (GPR). In addition, OSRTI has offered an internet-based training opportunity on field-based geophysical techniques (including GPR)--an archived version of the seminar can be found at: http://www.clu-in.org/conf/tio/geophysical_121201/.

Finally, general information about geophysical information, can be found at the Association Environmental and Engineering Geophysical Society web site.

Q. I am concerned about the possibility that operating a GPR (Ground Penetrating Radar) device might be a health hazard. It broadcasts high frequency radar waves (into the ground) and the latest technology has the transmitter pulled about 4 ft behind the operator. I have a son who developed a brain tumor and am cautious about these things now. What does the EPA think about this tool's safety?
A. Currently there is a lot of research being conducted throughout the world to evaluate the health effects of non-ionizing electromagnetic radiation and high frequency microwaves (see the links below).

• http://www.who.int/mediacentre/factsheets/fs226/en
• Safety and Health Topics: Radiofrequency/Microwave Radiation

There is some evidence to suggest physiological effects from these types of technologies however a direct link between exposure to radar waves and cancer or other health risks has not been established. As a precaution agencies such as OSHA do provide regulations concerning exposure limits. These can be found at the following links.

Nonionizing Radiation
Agency/Page Title Web Address	Keyword
OSHA Nonionizing radiation Regulations http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10627&p_text_version=FALSE	Nonioninzing Regulations
University of Texas Environmental Health & Safety http://www.utexas.edu/safety/ehs/radiation/lasers.html	Laser Safety
National Institute of Health http://www.niehs.nih.gov/emfrapid/home.htm	EMF health effects
FDA Cell Phone page http://www.fda.gov/cellphones/	Cell Phones
Medical College of Wisconsin http://www.mcw.edu/gcrc/cop/cell-phone-health-FAQ/toc.html	Cell Phones
FDA Center for Devices and Radiological Health http://www.fda.gov/radiation-emittingproducts/radiationemittingproductsandprocedures/tanning/default.htm	Sunlamps and Tanning
Federal Trade Commission http://www.consumer.ftc.gov/articles/0129-indoor-tanning	Tanning
Occupational Safety & Health Administration https://www.osha.gov/SLTC/radiation_nonionizing/	Radio and Mircrowave
Federal Communications Commission http://www.fcc.gov/oet/rfsafety	Radio
Occupational Safety and Health Administration http://www.osha.gov/SLTC/radiation_nonionizing/index.html	Non-ionizing Radiation

EPA does not have a recommendation on the safety of various GPR instruments at this time.

We recommend limiting exposure to high frequency radar waves by operating the instrument in accordance with manufacturers operation and safety guidelines.

Q. I am in an uncharted area and there are many unmarked utilities and possibly UXOs. I would like to get a rough estimate of the cost of your GPR and details I can present to my leadership for consideration.
A. GPR can be procured as a service. We recommend contacting a geophysics firm in your area to evaluate potential costs for the survey, data interpretation, and work products such as maps and survey reports.

You will also need to supply information on the size of the area and approximate total depth of the survey to assist in developing cost scenarios.

Purchase cost and training information from vendors as well as additional links can also be found in the Ground Penetrating Radar section. Interpretation of data can be difficult and personnel familiar with instrument operation and data interpretation are recommended.

Q. I need information, documents or links on how to perform and interpret IP gradient array surveys.
A. A broad range of web-based resources are available. Examples of websites providing information about IP from geophysics vendors and government sources are listed below.

• http://www.aurorageosciences.com/services/mining_exploration/geophysical_surveys/induced_polarization_surveys/
• http://www.fugroground.com/geophysical-services/
• http://www.cflhd.gov/resources/agm/geoApplications/SurfaceMethods/934InducedPolarization.cfm
• http://www.negeophysical.com/
• http://www.eos.ubc.ca/ubcgif/iag/methods/ip.htm
• http://web.archive.org/web/20071015063948/http://www.gp.uwo.ca/es320/lecture.html

Q. I am trying to find a portable device to find water underground, this is to make a well in a farm, can you tell me if such a device exists?
A. Resistivity is a geophysical technique that can be used to identify potential areas of groundwater. Although the equipment is portable and can be used to evaluate subsurface geology at hundreds of feet below ground surface, data interpretation is difficult and requires a vendor to evaluate the raw data. The technology is also subject to some interferences and may not work well at locations with lateral variations in soil.

Your best option is to consult a local geological survey office or University. These establishments will likely have extensive reference materials, including well records, geologic maps, downhole and surficial geophysical logging records, core logs and other information concerning water availability in your area. A professional or University geologist may also be able to give advice concerning local formations.

Q. In some of our projects the soil contamination extends from surface to 9-12 feet below surface. There is often a short change of soil type from sand to sandy loam to clay to clay/aggregate. When we treat at the lower levels the penetration of the consortium/nutrient is very limited. We have used Calcium Peroxide 5% as a pre-treatment and make a penetration of about 2 feet. Not good! Any suggestions?
A. It appears that you are having difficulty getting delivery of nutrients to depth and would like specific suggestions concerning products that might improve the distribution of the nutrients to depth in a mixed sand and clay environment? It is important to have a good understanding of the geology, because often it may control the type of additive you might consider and ultimately the effectiveness of any attempt at improving nutrient introduction. Tools such as a cone penetrometer (CPT) rig can help increase your understanding of the geology at a site on a much finer scale. The CPT uses the relationship between sleeve friction and tip resistance to map the geology at a site on a finer scale than is usually possible using standard logging methods. It can also increase the frequency with which lithological data can be collected in support of a nutrient introduction scheme. Some good mineralogical data can also assist when deciding if a specific additive will be useful. Physical methods such as fracture induction can also be used under the right conditions. In short, the geology will likely control the effectiveness of any nutrient delivery system. If the geology is not favorable and the depth of contamination is minimal, then perhaps you should consider the additional expense of ex-situ treatment. Using an ex-situ method, samples can be homogenized physically and the restoration environment more easily controlled.

Q. What citation(s) can you give me for collecting chloride samples from monitoring wells? This is not for investigative purposes. This is for monitoring the "overall" aquifer. Also, what guidence is available for spacing/placing monitoring wells around a facility?
A. Chloride is part of the anion suite and these anions are generally used to monitor aquifer water quality (is it a viable drinking water aquifer? or is there a beneficial use?) and indicate conditions for natural attenuation or remediation. It seems to me that assessment of the site conditions (for example, develop a conceptual site model) and the professional judgement of a geologist is needed to assess placement of monitoring wells. Every site has unique geologic conditions and varying contaminants that have different fate and transport mechanisms that will dictate a monitoring program. An excellent place to start is:

"Study and Interpretation of the Chemical Characteristics of Natural Water," John Hem USGS Water supply paper 2254.

This reference talks about chloride and how it fits into water quality and geochemical evaluations to determine water characteristics at a site. There is also some discussion of sample collection activities.

If the site is moving into the remediation phase or there will be some statistical analysis of water samples to determine the number of samples necessary to characterize the groundwater with a certain degree of confidence. Here are some good references.

1. "Statistical Methods for Groundwater Monitoring" - Robert D. Gibbons
2. EPA guidance G-9 is also a good reference for statistical analysis of data.
3. Methods for Evaluating the Attainment of Cleanup Standards Volume 2 - Groundwater

Q. My mother is wondering how I am doing with my new sampling job as a sampling expert (describe what my job is)? What plans must be followed? What dangers there are; what contamination is; what chronic effects can occur to her and yourself with the contaminants.
A. There is a very nice section on the U.S. Environmental Protection Agency's (EPA) web site that is devoted to kids. Please go to: www.epa.gov/kids/.

There is a student section in there that describes the various air, water, and solids programs and lists some contaminants.

Q. Could you tell me why the lab results are so different from field data on the effluent and influent samples taken from a soil vapor extraction? A PID and a FID are used in the field.
A. We presume that you mean the total VOCs reported by your laboratory method(s) do not agree well with the field readings reported by your PID and FID. There are many possible reasons why lab results could differ significantly from PID/FID results.

First, sample matrix effects. PIDs and FIDs respond to a broad range of chemicals. Many of these chemicals are not on typical target compound lists analyzed by laboratories. This could bias the laboratory results low versus the field data. Conversely, depending on the site and the type of laboratory method used, some matrix interferences could affect the laboratory data but not the field data, biasing the lab results high.

Second, PID/FID response. PIDs and FIDs don't respond well to certain VOCs. For example, FIDs don't respond well to many chlorinated VOCs. PIDs don't respond to methane, and many PID units may not be sufficiently powerful to measure some chlorinated VOCs. If your SVE system is addressing VOCs to which your field instruments do not respond well, the field data could be biased low relative to the laboratory data.

Third, instrument calibration and control. Calibration and quality control (QC) protocols tend to be very cursory for PIDs and FIDs, and the operation and performance of these instruments can vary widely based on field conditions. Most of the time, for example, these instruments are calibrated using standard gases that are not target analytes. Calibration and QC protocols are usually more rigorous for laboratory methods, involving specific target analytes of interest for the project. However, the performance of laboratory methods can also vary based on sample matrix effects, instrument cross-contamination, and other factors.

One or more of these and other factors could be affecting the field or laboratory results, or both. In short, it seems that you have a comparability issue between the field and labatory results that needs to be further addressed by the field team and the laboratory. Do you have a chemist on your project team? Knowledgeable technical staff need review the data, working with the laboratory and the instrument manufacturers as necessary to confirm that the methods were applied properly and understand the reasons for the differences in the results.

Q. I am considering investigating a site using a flourescence technology. Can you explain the primary differences (if any) between ROST-LIF and UVIF? Include pros and cons of each?
A. We are aware of three primary types of downhole fluorescence technologies. Two are lasers tools that radiate a sequence of intense laser pulses of light at a specific wavelength. The laser is then turned off while the resulting florescence is measured. The two laser induced fluorescence (LIF) systems are operated by Fugro Industries Inc. and the US Department of Defense (DoD). The Fugro system is the only one available commercially. The Fugro system is called the Rapid Optical Sensing Tool (ROSTTM) and emits a laser pulse at a wavelength of 290 nanometers. Using the ROSTTM total fluorescence intensity measurements can be used to estimate the presence or absence of light, moderate, and heavy range hydrocarbons (gasolines through motor oils). Data can be obtained concerning the type of hydrocarbon present by examining the specific wavelengths emitted after excitation by the laser.

The DoD LIF tool is known as the Site Characterization Analysis Penetrometer System (SCAPS). The DoD system is only available to federal facilities and has similar capabilities to the ROSTTM except it cannot provide wavelength fingerprints used to estimate the type of hydrocarbon present. Both are excellent tools for delineating the nature and extent of petroleum products, but as with all fluorescence tools they are susceptible to interferences from mineral fluorescence, such as that from calcite, commonly found in bay muds and some sands and silts. Caution should be taken to collect soil samples in apparent petroleum bearing zones to assure that the LIF response obtained is representative of the condition being evaluated. Both of these systems can also generate cone penetrometer readings which are extremely useful for delineating geologic conditions present at a site. Both systems are relatively expensive to procure at between $2,000 and $5,000 dollars per day. However, at large sites or at sites where the distribution of contaminants has been difficult to determine, these tools are extremely valuable. Large or small complex sites can be characterized in a very short period of time sometimes accelerating cleanup tremendously.

A third type of fluorescence instrument is also available, which uses a UV fluorescence bulb down hole. This may be the technology you referred to as UVIF, otherwise also know as a Fossil Fuel Detector (FFD) system available through Vertek, a division ARA Inc. This technology is similar to other LIF technologies except it does not collect full spectrum data, rather an electrical pulse is recorded in one or two down hole photo multipliers. The technology has a similar sensitivity to that achievable using LIF, but speciation is not possible except in a crude sense. The two down hole photomultipliers do provide some indication as to the response from light versus heavier fuels. Excitation is at the 254 nanometer wavelength and photo multipliers geared towards gas and diesel range hydrocarbons and then heavier coal tar or motor oil products. More information on this technology can be obtained from www.vertek.ara.com. This technology can provide the same cone data and can like the other cones be equipped with a video sensor. The cost and power requirements are significantly less than those for an LIF system at between $2,000 and $3,000 per day.

Q. I have been reviewing monitoring data for priority pollutants. During my review I have notices that many chemcials are listed by a different chemcical name than the chemcical name identified in the California Toxics rule or other guidance document. Is there a list of chemical names and cross reference names available? Is there a list available to identify sampling analyses for chemicals such as chlorinated phenolics? I imagine chlorinated phenolics is a suite of chemcicals and I am not sure what chemcials a discharger would submit to comply with a request to sample chlorinated phenolics.
A. The following website is a location where you can try and match chemical names of different types - the EPA List of Lists website. http://www.epa.gov/emergencies/tools.htm#lol. Hopefully you will find this helpful in many future activities. You can also search what chemicals are regulated by which program. Chlorinated phenols are easily detected using many analytical methods. SW-846 methods for phenols can be found at the following website: http://www.epa.gov/epaoswer/hazwaste/test/main.htm.

Most of the chlorinated phenols that are regulated are analyzed for using the gas chromatography/mass spectrometry (GC/MS) method 8270. The primary drivers for risk in water are usually directly correlated to the degree of chlorination. The most highly toxic of the phenols in water is usually pentachlorophenol. Pentachlorophenol has a maximum contaminant concentration (MCL) of 1 part per billion in groundwater/drinking water. Because of the nature of the aromatic ring with a hydroxyl ion attached there are 5 types of chlorinated phenol -- chlorophenol, dichlorophenol, trichlorophenol, heptachlorophenol, and pentachlophenol. Most of which are on the 8270 method target analyte list. It should be noted, however that method reporting limits may be less that adequate for more toxic chlorinated phenols like pentachlorophenol. Reporting limits are usually in the 10 to 20 ppb range for method 8270 in water. In order to improve reporting limits, a modified version of the chlorinated herbicide derivitization procedure in SW-846 method 8151A can be used. This method is complex to apply and can be problematic, so sufficient startup testing should be conducted to verify performance. Alternatively, the GC/MS method can be modified for operation in the selected ion monitoring (SIM) mode to improve method reporting limits, but the target analyte list must be modified and shortened because of limitation placed on the mass spectrometer when operated in the SIM mode.

Q. Do you have previous publication on radioactive screening using materials such as clays and anthills?
A. Your question is outside the scope of this web site and we have no knowledge on this subject.

Q. On large agricultural sites (40 to 6 acres) with assumed uniform pesticide application, how many discrete samples would you composite to evaluate pesticide residue in soil?
A. To estimate the appropriate number of discrete samples that should be composited from a pesticide site will depend on the expected data distribution characteristics and the sensitivity required (usually driven by an intended use or regulatory threshold limit value). If you are planning to conduct a compositing program there will be physical limitations that can also come into play. For typical pesticide analyses, you can composite in several ways. You can split a sample physically after collection in the field, and then take equal 3 gram aliquots of up to ten homogenized discrete samples and place them into a single composite. Method 8080 then calls for the digestion of a 30 gram sample prior to analysis. This approach limits the sensitivity of the analysis relative to decision making. For example, if the quantitation or method reporting limit for a particular compound was 1 part per billion (ppb) then you could definitively say under the above described scenario that this same compound did not exceed 10 ppb in any one of the discrete samples collected. In other words, this approach effectively increases the individual sample reporting limit. However, it is a good method for estimating the mean provided that the underlying discrete sample data population distribution is normal or lognormal. The heterogeneity of pesticides in soil can also pose a problem using this approach because it is easier to miss the nuggets in which the contamination resides. It is our experience that even under the more apparently heterogeneous of distributions, the observed distribution can be very spotty. To get around the potential that you might miss a pesticide because you collect only a tenth of the total amount of soil usually collected, you can collect up to ten samples at full mass, 30 plus grams, and then perform the method extraction and then combine the extracts. This method is the one we prefer because it limits the impacts of small scale sample heterogenity.

If this is a regional type of study you may want to select a method initially and then analyze the data as it comes in to determine if sampling or method modifications are needed. By plotting up results in terms of cumulative frequency of detection versus concentration, it is possible to begin to understand what type of variability of results you can expect. These types of plots are called probability plots. It is also possible that you can take your preliminary results and begin to estimate the mean and associated standard deviation of results. From this data you can estimate if the compositing scheme you have designed is adequate. If uncertainty still appears to be too high to predict if a property is above or below some regulatory threshold limit value it may be necessary to consider the use of methods that can dramatically increase your ability to conduct discrete sample analyses, such as immunoassay test kits. Immunoassay test kits are good for determining the absence of many pesticides below some level, usually in the low parts per billion (ppb). If they are used in this way it can be possible to collect many samples across a site and obtain results in a very short period of time. If positive results are obtained in the field, a composite or discrete sampling and fixed lab analyses can be focused on areas where it appears to be dirty. Rank set sampling can also be used to identify classes of sub-areas where more definitive analyses may want to be considered. For more information, see the following guidance documents at http://epa.gov/quality/qa_docs.html#guidance (Guidance on Choosing a Sampling Design for Environmental Data Collection (QA/G-5S) and Guidance for Data Quality Assessment: Practical Methods for Data Analysis (QA/G-9)).

If the objective is to determine what background levels should be considered for certain pesticides, we suggest that a random or non-nodal grid sampling method and discrete sampling be considered. This will lower method reporting limits and make the data of the maximum value in terms of background determinations. Dual column GC methods performed in the field or even mass spectrometry methods can be used depending on the level of sensitivity required. Solid phase extraction methods can be used in some cases to improve sample throughput. For further information on this subject or to request direct support at no cost to you, go to http://brownfieldstsc.org/. This is a challenging question and without more information concerning the purpose of your study and some preliminary data, it is not possible to provide definitive answers to your questions.

Q. What is the cheapest and most accurate way that I can collect and quantify concentrations of sulfate, aluminum, manganese, and iron in sediments at a natural wetland? Do you know of any references I could look up of how to do this and a good company to send the samples off to be analyzed?
A. Assuming you would like sulfate concentrations in the part per million (ppm) range and metals in parts per billion (ppb) range, there are a number of options available to you.

Sulfate concentrations can be determined by a number of techniques commonly used in commercial laboratories, however a solid matrix (in this case sediment) can introduce some complexities and difficulties. One option would be to employ an ion chromatography (IC) technique such as EPA method 300.0. This is a relatively inexpensive method (approximately $15 to $20 per sample) and can include analyses for a number of anions including sulfate. Other anions include chloride, bromide, fluoride, nitrate, and nitrite. Many commercial laboratories use a de-ionized water solution to extract the anions for analysis from a solid matrix and the sample is filtered (usually a 40 micron filter) and analyzed like a liquid sample using standard IC analysis. A sediment may pose some difficulties as the fine grains may stay suspended in solution and it may be difficult to filter enough liquid for IC analysis.

Sulfate, iron, manganese, and aluminum may also be measured using analytical test kits from Hach http://www.hach.com/ but analysis of sediment requires digestion of the sample using a digestol unit (costing approximately $1,200) and sulfuric acid. The analysis also requires the use of a spectrophotometer (for example the DR2400 for approximately $2,000). This equipment can also be rented at lower costs through environmental equipment rental companies such as Hazco or Geotech. Low ppm detection limits can be expected using this technique

The most definitive and simplest method for analyzing metals in sediment would be to employ a standard EPA method for metals analysis such as SW-846 method 3010/6010. This method uses an acid digestion of the sample and analysis by inductively coupled argon plasma (ICAP). It is the standard industry analysis for metals in sediment or soil and can achieve accurate low level ppb qualitative and quantitative results. Many commercial laboratories conduct this test routinely and individual metals analysis can be purchased for approximately $20-$30 for the first metal and $5-$10 each additional metal. Cost vary by commercial laboratory and may be found at even lower prices. A search of local and national environmental testing labs and some calls concerning pricing and analysis technique would provide a clear picture of the costs associated with this type of analysis. Samples can be easily shipped via Fed Ex or other carrier.

Q. What sampling methods and containers are used to collect deep well and aquifer water samples for dissolved gas analyses. It is my understanding these must be designed to prevent degassing.
A. The Waterloo sampling system originally developed by the University of Waterloo is now deployed by a number of commercial vendors. The system can be deployed on a direct push or other drill rigs capable of reaching 500 feet or more below ground surface. The system has most recently been configured to evaluate VOC sites however samples are collected and maintained at in-situ pressure and may be analyzed for dissolved gases. We recommend speaking with a commercial vendor of the system (http://www.stone-env.com/profiling/ or http://www.precisionsampling.com/waterloo_groundwater_profiling.html) to evaluate whether the system can be configured for collection of dissolved gas samples. It may be necessary to use nitrogen or another enert gas as a purge gas if you want to get some idea of what the dissolved gas content of groundwater is at your site. Under artesian conditions it is possible to estimate the dissolved gasses in groundwater. Degassing during sampling, which us tied to changes in temperature and gas distributions make it difficult to purge and measure accurately gas content in groundwaters.

Some information concerning sampling for dissolved hydrogen can be found at http://www.microseeps.com/.

For existing deep wells we recommend using techniques employed by the USGS and other geochemical isotope sampling firms. All references we could identify, specify the use of copper tube samplers as a way to collect dissolved gas sample for deep well samples. Using this method dissolved gasses are trapped into a copper sleeve down hole where pressure and temperature conditions are representative of groundwater at the depth where it is being sampled. See http://web.archive.org/web/20060904062150/http://www.inscc.utah.edu/~ksolomon/Procedures/Collection%20of%20Dissolved-Gas%20Using%20Copper%20Tubes%20in%20Dedicated%20Pump.htm and http://www.cc.utah.edu/~ahm2/Chapter2.pdf.

Q. Where would I find information/methods on Tedlar bag manufacturing specifications and decontamination? Is it all under TO-14? or elsewhere/not written?
A. For manufacturer specifications on the actual Tedlar material you may want to look at the Dupont site (http://www.dupont.com/tedlar/).

Here are a few links to information about Tedlar bags:

•  Tedlar Bag Sampling
  
•  TedlarBag.com
  
•  http://www.skcgulfcoast.com
  
•  http://www.airtoxics.com

Decontamination and reuse of Tedlar bags is not recommended, especially when sampling for compounds in the low part per billion by volume (ppbv) range. Once a bag is used the active surface coating the inside of the bag has been exposed to moisture and possibly volatile organic compounds (VOCs) which may become irreversibly adsorbed. Even with a series of purges with certified inert gases, many of the VOCs may not be removed, placing future analytical results in question. At around $15 per bag it may be in your best interest to purchase new bags for each sample.

Q. For a simple comparison of two different treatments per site area compared to an untreated control with concentrations of an alkane in ppm can you suggest a statistical design or software?
A. The answer to this question will depend almost entirely on the data distribution, the objectives of the sampling program, and the power and confidence levels needed to support decision making. If distributions are parametric (log normal or normal), then standard statistical methods and unbiased sampling approaches using either a nodal systematic grid type of pattern or a simple random method can be applied (see QA/G-5S at Guidance on Choosing a Sampling Design for Environmental Data Collection). Where there is significant biased introduced by media heterogeneity, a more biased or stratified approach may be needed to adequately decide if and where a treatment technology is working better or worse as compared with a control area. The problem is usually best solved by attempting to increase sampling density regardless of the sampling pattern used and increasing information value through the use of a field-based technology, which can take many more measurements for the same cost. This approach invariably results in improved decision support and power of the test, but without more information on a specific site it is difficult to make a better recommendation. I generally prefer the use of a non-nodal random systematic grid patterning where the site is laid out into grid sectors and then a single sample or composite set of samples is randomly collected within each grid sector. This ensures site coverage while at the same time limits the systematic bias, which results when one uses a strictly systematic nodal grid pattern distribution.

There are numerous software packages which can assist you in designing a sampling and analysis program such as Visual Sampling Plan (VSP) or Spatial Analysis Decision Support (SADA). While these programs can be helpful they are designed around standard statistical methods and more or less systematic or random approaches to sampling. We recommend that you carefully look at the distribution of available data at the site and the principals described in Guidance for Data Quality Assessment: Practical Methods for Data Analysis (QA/G-9) found at the above mentioned EPA quality staff website before selecting a site specific approach.

Q. We have performed some sampling for a site using USEPA method 0010. Is there any methods that are not too costly that can be operated by on site personnel. The purpose of the method would enable the site personal to have a check on how the process is operating rather than do the full test as above. I would expect a total VOC method would be suitable. Is there an electronic method that can detect low levels of VOC where the VOC's are pesticides such as aldrin and DDT. The site is doing soil remediation from a contaminated site.
A. To our knowledge, chlorinated pesticide compounds such as aldrin and DDT are not considered volatile organic compounds (VOCs) and cannot be analyzed using the same methods as conventional VOC analyses such as SW-846 method 8260B http://www.epa.gov/epaoswer/hazwaste/test/pdfs/8260b.pdf.

Based on the information you have provided we assume you are sampling the gaseous and particulate matter from an incineration unit used to remediate soil contaminated with semi-volatile compounds (SVOC) and chlorinated pesticides.� Although there are some field analytical tools available for chlorinated pesticides, such as immunoassay test kits available from Strategic Diagnostics http://www.sdix.com/ProductCategory.asp?nCategoryID=4, the complexity of the analysis is derived from the sample collection process (EPA method 0010) and extraction steps necessary to get contaminants into a solvent solution for analysis.� We recommend you determine exactly what compounds you are looking for and consult with SDI technical support to see if immunoassay test kits are applicable for this matrix.

There are also many GC/MS analyzers that can collect and analyze the gas and particulate matter components exiting the remediation system.� Again, sample collection and extraction for chlorinated pesticides increase the complexity of the analysis.

The HAPSITE http://www.inficonchemicalidentificationsystems.com/en/index.html field portable GC/MS can provide analysis of VOCs in ambient air and can also be configured with and electron capture detector (ECD) to conduct pesticide analysis. Other manufacturers include SRI http://www.srigc.com/ and Photovac http://www.photovac.com/ Again we recommend you speak with the manufacturer to see if the instrument can be configured to analyze your site specific matrix and compounds of interest.

Q. I simply do not know how to find the unbiased estimator of the total of a finite population, and also its variance for a two-stage sampling method using either one of the following designs: Using the weight variable approach, find an unbiased estimator of the total of a finite population and the variance of this estimator using: design1. stage one: n primaries from N selected with equal probability and without replacement; stage two:m sub i secondaries selected from M sub i with unequal probability with replacement and design 2: stage one: n primaries from N selected with unequal probability and with replacement; stage two: m sub i secondaries selected from M sub i with unequal probability with replacement.
A. This question pertains to probability statitics and is not related to the topics covered in this web site. We are sorry that we are not able to help you with your question.

Q. Is there a "Standard test procedure for evaluating various leak detection methods" in underground pipelines for transportation of crude oil and refined.
A. This question pertains to petroleum products and is not related to the topics covered in this web site. We are sorry that we are not able to help you with your question.

Q. Total lead concentrations found in the soil do not correlate with the TCLP data on the respective samples. I need a guidance document or mathematical/statistical approach that can support the position that soils with a total lead concentration of "X" will have a corresponding TCLP concentration of less than 5 mg/L to render it non-haz.
A. It may or may not be possible to determine a reasonable correlation between total digested metals concentrations and TCLP results, particularly if there are numerous forms of lead present at your site. For example, lead oxide (more soluble) versus lead sulfide (less soluble). Lead comes in many different forms with variable physical properties. Correlations are possible when enough data can be collected and when population distributions are reasonable (normal or lognormal) by simply plotting totals metals versus TCLP and performing standard statistical analyses. Statistical methods should only be attempted when supported by a chemist who can provide assistance if analyzing for the presence of outliers, which can result from sample heterogeneities (the "Nugget" effect) and other sample preparation related sources of error. I have attached some example plots for a data set we have been working on recently showing very poor correlation with an outlier left in the data set followed by the same correlations with an outlier removed. With the outliers removed the correlations (R squared values) are vastly improved, but still not what is commonly used as a cutoff when doing these types of geochemical correlations of 0.68 or 68 %. In this one case we are still refining our correlations through the collection of more information and we will likely even consider truncation of our data set to include just those points surrounding the decision point, say 5 ppm TCLP versus 2000 for totals. This is reasonable when points that stray outside this general range will obviously fail or pass the TCLP respectively. In this way we might be able to improve our correlation to below this magic number for the data set as a whole. In addition to making a strictly statistical comparison it is also necessary to look at the variablilty in you analytical results and then to assign a safety factor below the final identified field-based total metals action level. For example, in my case if my best fit line predicts with a R squared value of greater than 68 % that a total lead concerntation of 2,400 would result in an exceedence of the TCLP regulatory threshold value of 5 ppm and the standard deviation of my total metals results in the region where desions might be made is plus or minus 300 ppm, then I might assign a final field-based action level of 2,100. Making reasonable correlations when mineral forms are complex can be very difficult, because fo differences in solubility, so even with a large data set correlations may not be possible.

Q. I would like to use some information from your site in an assignment I am writing as part of my undergraduate degree. Please could you tell me how to cite the information properly. Thank you.
A. The information from the web site is developed jointly by the U.S. Environmental Protection Agency's Office of Superfund Remediation and Technology Information and the U.S. Army Corps of Engineers.

Q. AAs a regulator, I am constantly arguing with consultants regarding the appropriate field screening instruments for hydrocarbon (HC) contaminated soils. I contend that a PID should be used for lighter weight compunds such as gasoline and an FID used for heavier compounds such as diesel and fuel oil. They are producing work plans which state that either a PID or FID will be used for screening purposes, regardless of the HC of interest. I realize that the lamp of a PID is controlling factor in detecting HC. With an FID any type of HC will be detected. Can you confirm or substantiate my reasoning?
A. PIDs and FIDs are not differentiable based on the types of hydrocarbons they detect -- they both can measure a broad range of hydrocarbons, from light to heavy. Instead, PIDs are distinguished by their higher sensitivity relative to FIDs. This makes PIDs potentially better for heavier hydrocarbons, which are less volatile (producing lower gas-phase concetrations). PIDs are also better for sites that have a broader mix of VOCs, such as halocarbons and inorganic gases. FIDs, on the other hand, are best for measuring high concentrations of total hydrocarbons, including methane (which connot be measured by PID).

Q. Dear colleagues, I would like to have more information about hand operating soil gas samplers. We need to buy some of them for our reseach purpose (oil and gas pipe line control).

Q. I would like to ask you send me some information about hand operating equipment for soil gas sampling in an anaerobic environment where hydrogen, hydrogen sulfide and methane are generated by microbial degradation of organic material. It will be nice to have a commercial offer for this set too.
A. Real-time monitoring of soil gas can be performed using hand-held photoionization detectors (PID) and flame ionization detectors (FID). PIDs can be configured to measure a broad range of volatile organic compounds (VOC) (including hydrocarbons, solvents, and inorganic gases), while FIDs are best used for the measurement of hydrocarbon gases only. Both types of instruments have limitations in regards to your needs. FIDs cannot operate in an oxygen poor environment (or where high concentrations of combustible gases may be present) and PIDs cannot measure hydrogen or methane. A great website for more information on PIDs and FIDs is http://www.processanalyzers.net/ .

In addition to PIDs and FIDs, some other handheld instruments may be of interest for your vapor monitoring needs, such as the Femtoscan (http://www.femtoscan.com/evm.htm), Scott personal gas monitors (http://www.scottinstruments.com/), and SKC hand held gas monitors (http://www.skcinc.com/gas.asp). Many of these companies make monitors for hydrogen, hydrogen sulfide, and other specific gases that may be of interest to you. Small portable gas chromatographs (GC) can also be used for soil gas and other types of vapor monitoring. See, for example, the Photovac Voyager (http://www.photovac.com/), the Agilent 3000 Micro GC (http://www.chem.agilent.com/Scripts/PCol.asp?lPage=180), and Baseline Industries GCs and personal monitors (http://www.baselineindustries.com/).

We suggest reviewing the information at these websites and contacting the vendors for further information and costing. An important question to answer in selecting and applying the best technology is how the soil gas vapors will be sampled. Will you be pumping vapors from a borehole, or will you be using the instrument for ambient monitoring? You should work closely with vendors and other vapor sampling experts in selecting a sampling and analytical approach.

Q. What technology would you suggest to use if I was interested in the bioremediation of a plume that contains 50-300 ppb of carbon tetrachloride?
A. We are aware of many bioremeditation treatment alternatives, which can be used to degrade carbon tetrachloride. Among them are the use of additives such as titanium citrate and vitamin B or the addition of hydrogen reducing compounds (HRC) or ozone to enhance natural degradation processes. A summary of available technologies can be found on CLUIN.org under technology focus areas and then bioremediation of chlorinated solvents. A publication is available on CLUIN.org at this location titled "Engineered Approaches to Insitu Bioremediation" EPA 542R00-008, July 2000 which could be of some assistance. Phytoremediation is also a possibility if you plume is sufficiently shallow. There is also a wealth of knowledge available on the Interstate Technology Resource Council (ITRC) website at http://www.itrcweb.org

Q. I was wondering if you would be able to send me some information on chemist/trace expert.
A. The question is unclear. Please provide additional clarification concerning the information you are trying to obtain.

It appears you are interested in information concerning experts in trace chemical analysis. There are several websites available with good information and helpful links to identify experts for you particular needs. These include http://www.envirosense.com/, http://www.envirobiz.com/, and http://www.envirotools.org/.

Q. Could you help me to find a solution for building/construction technologies that can be used on land where there is danger of soil contamination from heavy metals or VOC?
A. In terms of heavy metals you must keep in mind the types of exposure pathways. To our knowledge there are not specific building/construction technologies used for heavy metals. The concern for metals is the source and any associated exposure pathways. If you limit exposure to metals by removing sources (excavation and disposal) or pathways for exposure this should be sufficient. Physical techniques for limiting pathways include capping and stabilizing such that receptors (humans and ecological receptors) are not exposed to the metal contamination.

For remediation of VOCs there are numerous venting technologies that can be included in the building design/construction that would limit exposure of building inhabitants to VOCs. Some guidelines for building construction can be found at http://www.cmhc.ca/publications/en/rh-pr/tech/93-202.pdf, http://www.nsc.org/ehc/indoor/sbs.htm, http://www.epa.gov/iaq/pubs/ventilat.html.

Q. I work at the University.� My research area is arsenic waste coming from the copper industry.� We are developing a new process and I would appreciate a lot if you could send me the USA EPA Method 1311 (TCLP) procedure to test solids coming from a S/S process.
A. Method 1311 procedures can be found at http://www.epa.gov/epaoswer/hazwaste/test/pdfs/1311.pdf