There are a number of factors to consider prior to determining which liquid sampler is best for your particular application. Listed below are some of the more common facts and myths about sampling practices. Those that perform liquid sampling know that the task is awkward, cumbersome, and subject to device and operator inefficiencies. These constraints led us to design a value-added sampler that addresses many of the different and diverging criteria. The items listed below represents a collection of user inputs from fieldwork, tradeshows, and E-mail responses. Please read on.
Art or Science: Operators assigned to drum sampling are told: "there’s a whole lot of art and a little bit of science in liquid sampling", and when finished, they wonder if there’s any science. The main driver behind the Liquid Sampler design was to standardize the collection process, irrespective of the operator, workplace, or environmental influences. It is well known that sampling represents the greatest fraction of the measurement error, yet there exists parity in our understanding and response to error analysis. Laboratory methods and errors which are tightly monitored and controlled by upper and lower confidence limits, proficiency and accreditation samples, and quality control protocols, etc. Millions are spent for the finest GC/MS, ICP or LIMS, but a blind eye is often turned when considering new sampling methodologies and hardware. The Liquid Samplers have been designed to reduce, if not eliminate measurement errors and thereby improved data quality, consistency and compliance.
Data Value/Data Worth Pyramid: This adage is common to the environmental and waste management circle, it goes something like this: An operator ($10/hr) collects a sample using a $1 drum thief, the chemists ($40/hr) uses a $80K GC for analysis, the lab manager ($60/hr) reports the data on a $100K LIMS network, the consultant ($200/hr) uses the data to design a control technology ($500K), and finally the decision maker (or public servant) relies on the data to set public policy and funding priorities. The lifecycle costs are always difficult to quantify for these examples, but experience shows that the propagation of cumulative errors cost exorbitant amounts. If your anywhere along this data food chain, remember to look back and question the base element to all data collection activities (i.e. sampling).
Method Comparability: Washington State University and DOE/Pacific Northwest National Lab (PNNL) has conducted a comprehensive methods comparability study of commonly used liquid samplers (Drum Thief vs. COLIWASA vs. Liquid Samplers). The findings demonstrated that the precision and accuracy associated with the Drum Thief and COLIWASA-methods are error prone and highly variable. The study examined device-related and operator-related errors. The findings indicated that Liquid Samplers improve all aspects of sampling tasks.
Costs and Productivity: Sampler unit cost is the most often stated determinate prior to buying, but many believe that this is a short-sided view of the buying process. Productivity should be the measure by which sampling products are chosen. The sampling process should be normalized, such as samples/minute or drums/hour, this way all factors are assessed, not just the cost of sampling hardware. Analysis has shown that operator time is the driving factor influencing cost. The Liquid Samplers can collect a sample in a fraction of the time that it takes a COLIWASA or Drum Thief.
Industrial Hygiene and Safety Compliance: Our sampling technology was designed to accommodate and meet the ever-changing regulatory requirements. OSHA stipulates that employers must maintain a constant awareness of better technologies to mitigate operator exposures. These regulations specifically state that engineering control measures will be integrated where there is a potential for worker risks. Most people that we’ve talked to agree that sampling RCRA waste is an exposure rich environment. Using established Industrial Hygiene hierarchy, an employer can take tremendous strides in improving workplace safety with minimal costs.
SW-846: What started as an EPA guidance document has been swept into standard protocol. In the late 70’s when States were looking for RCRA sampling and analytical methods, they (the States) quickly promulgated this "guidance" document into their administrative codes. The net effect is that many states governments (and contractors) are now held to using these antiquated methods. Although new technologies are developed to assist the efficiency of operations, they are often cast aside because of standard practice claims. The movement towards performance-based methods should help to integrate new, improved technologies. The EPA has been working aggressively with ASTM to update these methods. Today, the Liquid Sampler has been included in these method manuals.
EPA "meets and exceeds": Many vendors often spout this product claim when justifying their technology. For sampling technologies this doesn’t mean much since the Agency sidestepped the requirement to demonstrate PAARC parameters; such as, representative ness. See RCRA Subpart C, Characteristics of Hazardous Waste, 261.20, Special Comment "...sampling methods are not being formally adopted by the Administrator, a person who desires to employ an alternative sampling method is not required to demonstrate equivalency..." Therefore the door is wide open for anyone to say anything about their sampling technology. This standoffish approach has caused great confusion within the sampling industry. We are hopeful that the efforts conducted by ASTM, EPA, State Programs, etc. will help bring new light and priority to sampling issues.
Representativeness: All sampling tasks start with the desire to collect a truly representative sample, but ends with the need to get a full sample jar. As noted, liquid sampling from drums, tankers, or lagoons is difficult, and the requirement to collect a sufficient sample volume often becomes the driving force. This debate will go on and on about what’s representative, there surely are theoretical and practical limits. Representativeness is the most often cited criteria of the PAARC elements, but the least policed. We believe, and the data supports, that our samplers are the most effective at collecting representative samples.
Pollution and Spill Prevention: The advent of pollution prevention regulations brought about a new awareness of systems engineering and process improvements to eliminate, reduce or mitigate the generation of pollutants. In relation to liquid sampling, our product reduces the chance of spillage and the need for sorbent pads/wipes, since the operator never removes the sampler from the container. Using a Drum Thief or COLIWASA results in spillage on the drum, ground, or operator, since the method demands the removal (multiple times) of the sampler from the container.
Personal Protective Equipment (PPE): Layers and layers of protective gear (gloves, coveralls, apron, respirator, etc.) are donned to protect the operator from what’s inside the drum. It can be a real challenge, however, for the operator to lift a 40-inch, waste-laden tube up and out of the drum with all the assigned PPE. No matter if the task demands Level A, B, C, or D protective gear, our product line can accommodate without added personnel or control measures.
Data Quality Objectives (DQOs): The EPA states that the DQO process should be the fundamental basis for all data collection activities. Although this process can be very painful to the uninitiated, the steps leading to data generation, reporting and decision making is extremely systematic. The process challenges people to determine inputs, state hypothesis, assess errors, and document planning stages. We are hopeful that as the use of the DQO process becomes more universal, participants will question sampling practices and collection errors
Radiological Sampling: One of the most difficult industry challenges is the collection of radiological samples without cross contaminating the operator and surroundings. With conventional samplers the practice is plagued with environmental and operator risks. Although it is difficult to rid all health physics concerns, the Liquid Sampler’s product design minimizes many of these challenges (time, distance and shielding).
As Low As Reasonable Achievable (ALARA): This is a policy advocated by the Department of Energy (DOE) to allow for continual process improvement and the lowering of operator risk to hazardous materials, both radiological and chemical substances. Operators are empowered to assess and recommend changes to task assignments, thereby challenging traditional practices and invoking technological improvements. Various ALARA coordinators agree that the Liquid Sampler’s are the preferred devices.
Sludges: Many factors influence the composition of sludge deposited in drums. Items such as consistency, pack ness, particle size, density, etc., all affect the operator’s ability to collect a sample. Sludges require increased operator tact and finesse to get a representative sludge sample. Once inside the sample tube, the battle is half won (the easy half). If conditions are right, the sludge can act like a plug allowing the operator to remove the Drum Thief or COLIWASA. Once removed, the sludge can be dislodged. This practice is very messy. With the Liquid Sampler, once the plunger is seated into the sample tube, and then retracting the plunger lifts the material up the sample tube. After the liquid fraction is decanted, the remaining material can be collected by removing the head sections’ cap, gaining access to the sludges.