Posts by C&T

Update on Helium Shroud.

Posted by on Aug 18, 2013 in C&T Thought Leadership

C&T designed and built the first commercially available soil gas sampling Helium leak detection shroud in 2011. This device quickly became the industry standard for its simplicity, ease of use and compliance to published standards. We thought about what we and our clients wanted: a shroud that is light-weight; easy-to-use; efficient and compact.  And so we designed and created a kit that included all materials necessary for a two-person crew to sample 8-12 soil gas wells under Helium in an 8 hour day.  This shroud has been recognized by all users as the easiest Helium leak detector device to use of all available alternatives. But, we didn’t stop there.  We’ve recently improved the design of our soil gas sampling shroud by incorporating a more compact sampling train and a pressure gauge that allows the sampler to verify the pressure between the train and the well to record measurementsdemonstrating compliance to CA Department of Toxic Substance Control (DTSC) soil gas sampling advisory guidance. As of spring 2013, C&T’s shrouds have been employed sampling nearly 3,800 soil gas wells at more than 200 sites around the USA. Today C&T has an inventory of two dozen single train and several duplicate and dual depth Helium leak detection shrouds available to assist clients complete their soil gas sampling projects. C&T will also sample soil gas wells with and without Helium leak detection for clients who need these...

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Silent, but deadly.

Posted by on Jul 16, 2013 in C&T Thought Leadership

From dry cleaner facilities to superfund sites, volatile chemicals can migrate from the underlying and surrounding soils to the indoor air of nearby buildings. This ‘vapor intrusion’ (VI) can lead to serious health risks and might be the cause of some cases of sick building syndrome.    Homeowners and commercial property owners alike can hire environmental investigators to determine if any health issues might be caused by hazardous substances entering via VI pathways.  Of course, sites that are known to have been severely contaminated are also likely to require evaluation prior to any additional construction. As of July 2012, 23 states and the US EPA have issued draft or formalized guidance on evaluating VI pathways.   Typically the approach begins with simple conservative screening methods and gradually progresses toward more complex assessments involving increasingly greater use of site-specific data. For Californians, the latest information is available at: There are links there to the EPA resources such as as well. C&T offers the complete range of soil, water and soil gas testing services to assist investigators   in preparing conceptual site models (CSM) and other work products to determine the potential for vapor intrusion at contaminated sites that have or may have buildings on them. C&T also provides ambient air sampling and testing services to measure the presence of volatile organic compounds that may pose human health risks in buildings that overlay contaminated sites. p.s. we couldn’t resist the subject...

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The Signal and The Noise- C&T Style.

Posted by on May 16, 2013 in C&T Thought Leadership

Many clients focus on just the measurement value in their analysis report. However, there is always a margin of doubt regarding the accuracy of any measurement, even the most carefully performed. The EPA and DOD are heading towards changing the reporting requirements so both the value and the measurement uncertainty will need to be reported. To keep you up-to-date, below is some information about these new metrics and how different companies approach their calculation and reporting. Quite simply, Measurement Uncertainty (MU) is a quantification of the doubt about the measurement result. Error is the difference between the measured value and the “true value” of the thing being measured. Any measurement error whose value we do not know is a source of uncertainty. Why is uncertainty important to environmental tests and measurements? · MU provides data users a quantitative estimate of measurement quality · The MU may be needed to determine pass/fail criteria for data · The MU may be needed to decide whether tolerances or acceptance criteria are met In environmental laboratories, MU values are frequently derived from statistical evaluations of repeated laboratory control (check) sample (LCS) measurements. The basic statistical values used to determine MU are arithmetic mean (average), and the standard deviation (sigma) for the set of LCS measurements. Confidence levels for MU determinations are expressed as a multiple of the standard deviation. Standard uncertainty can be thought of as +/- one standard deviation (one sigma) and provides a confidence of ~ 66%. C&T reports MU at the 2 sigma level, ~95% confidence. For example, when C&T reports results from an EPA method 8020 test of a water sample for Toluene as 5.0 µg/L with a MU of +/- 1.1 µg/L (interval). The interval is twice the standard deviation of the average from the LCS data set. Two sigma confidence levels are ~95%. From the above statement, the data user can understand that the laboratory is 95% certain that the true value for Toluene in this water sample lies between 3.9 and 6.1 µg/L (2 sigma). Alternatively, if the sample were analyzed repeatedly, 95% of reported result values would fall between 3.9 and 6.1 µg/L. To complicate matters even more, different vendors take different approaches in choosing their laboratory control samples. Ideally, these will also be taken from a random sample over a range of dates to report the uncertainty without any additional biases. Unfortunately, some vendors choose a specific set of samples to make their intervals seem tighter though this is a misrepresentation of the actual...

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Why Accreditation Matters.

Posted by on Apr 21, 2013 in C&T Thought Leadership

Do you need to use an accredited lab?   The answer is yes — if you want to have confidence in the results and the comfort that the results will be accepted by regulators and your clients. Accredited labs provide trust and: Confidence – that testing results are accurate and reliable. Acceptance – of test results by other users and regulators. Risk Management – liability is reduced through defined standards of practice. Accredited labs focus on building and operating well defined and repeatable processes, ensuring accurate and reliable test results, establishing controls to monitor and ensure desired results and continual process improvement. Laboratory accreditation is critical to data users; it ensures test data are accurate,traceable, reproducible and cost effective. Laboratories are accredited by an assessment of their conformance to recognized standards of practice by accrediting bodies (ABs). Accrediting authorities (AA), typically state agencies, provide regulatory recognition as well as AB services. What kind of accreditation should the lab have? The gold standard, NELAP Supported by the US EPA and based on the international ISO 17025 standard, the National Environmental Laboratory Accreditation Program (NELAP) is the consensus standard of practice for environmental labs in the US. The US Departments of Defense and Energyextended and defined the NELAP standard (DoD/DoE NELAP) for their environmental test & measurements programs. What about the state accreditations?   Today, state environmental accreditation programs are more regulatory necessity than an assurance of conformity to any recognized lab standard. Most state laboratory accreditation programs are based in administrative law and ad hoc systems of laboratory assessment. New Jersey and Minnesota have recently recognized 3rd party ABs for NELAP accreditation services while retaining their AA by granting business licenses. ACIL, the national laboratory trade association, recently recommended 3rd party AB recognition as a way for CA to reform its “dysfunctional” ELAP. What accreditations does C&T’s have? C&T provides its customers the benefits of a lab accredited to the highest standards of practice.    Specifically, C&T is NELAP accredited by CA ELAP, and to the DoD/DoE NELAP standard and ISO 17025 by...

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Geek alert: Incremental Sampling Methodology.

Posted by on Mar 21, 2013 in C&T Thought Leadership

At first glance, testing soil seems pretty simple.   Grab a few soil samples from a few random locations in the testing area, take them back to the lab for some testing and you’re good to go.   But there are so many parts of the process where this can go wrong– here are just a few: 1.    How were the sampling locations chosen?  Are they representative?  Are there enough? 2.    Was a rounded tool or a squared off one used in the sample collection?  How deep did they go? 3.    Did the particulates in the sample settle during transport?   Did the lab then sample the sample from just the top layer? Fortunately, there are ways to approach the sampling and in-lab testing to help to mitigate these potential errors.    In today’s newsletter, we’ll review one that takes a thoughtful approach tokeep the costs down while the confidence goes up. Incremental Sampling Methodology (ISM, aka Multi-Incremental Sampling, MIS) is a sampling and analysis protocol designed to provide an unbiased estimate of mean contaminant concentrations in soil targeted for sampling.   ISM helps to minimize error and uncertainty associated with soil sampling through a systematic approach to field sampling combined withlaboratory subsampling protocols.  And often does this with fewer total samples taken. The field sampling aspects of ISM are sophisticated.  They are site and contaminant dependent and require an understanding of the site including its history, the expected heterogeneity, and features such as the likelihood of mobility of the analytes prior to developing the sampling design. Laboratory aspects of ISM are straightforward and involve sample conditioning and systematic splitting and subsampling. Sample conditioning prepares the sample for subsequent processing, e.g. drying, crushing, drying, sieving to uniform particle size. Systematic subsampling involves the use of pans, trays and splitters to obtain a truly representative subsample that is carried through one or more discrete testing protocols. The net result of ISM is that levels of statistical confidence and measurement uncertainty that would require a larger number of discrete samples can often be obtained with fewer incremental samples reducing overall cost and increasing data quality. Benefits of the ISM approach Improved spatial coverage of the site including areas of high and & low concentrations in proper proportions. Reduced errors associated with sample processing and analysis Truly representative laboratory subsamples Fewer non detects resulting in simplified statistical analysis Reduced measurement uncertainty yields more confident decisions C&T has the experience necessary to implement ISM at the field sampling level and of course, in the lab.   Our lab offers a variety of sample conditioning techniques including jaw crushers for concrete and rock, puck and ball mills for soil and other particle size reduction...

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