The “environmental marketplace” includes a dizzying array of emerging technologies targeting everything from air purification and energy conservation, to water resource management and environmental pollution monitoring. Focusing only on environmental monitoring as it relates to subsurface pollution management reveals some exciting new products and services that offer automated alternatives to sample collection and offsite testing. Current monitoring options range from telemetry-based sensor sondes for physical chemistry monitoring, to automated field analytical platforms providing continuous monitoring of specific Volatile Organic Compound (VOC) constituents and gases. In this article, I will discuss the current state of automated, unattended, Field Analytical Platforms and profile several emerging market examples.
Analytical testing for VOCs has come a long way from the traditional fixed-based and mobile laboratory approaches. Just as laboratories have increasingly turned to robotic automation for repetitive tasks like sample processing, environmental professionals are looking to deployable platforms and services that claim laboratory-grade VOC analytical results delivered remotely from the field. Being automated and telemetry-enabled, these platforms promise reduced unit analytical costs, higher sample density, improved temporal relevance, repeatable 24-hour reporting, and even automated response.
Selective detection of specific chemical analytes has always been a challenge using solid-state sensor hardware unless coupled with chromatographic separation (columns) and calibration standards. However, emerging technologies have automated lab bench methods for the field enabling quantified analysis of many analytes of concern. Where simple solid-state sensors or surrogate parameters fall short of meeting testing goals, analytical sensor platforms have begun to fill the gap. As an example of this trend, the decades-old Gas Chromatograph (GC) has gone from the lab bench, to the mobile laboratory, to smaller portable devices capable of onsite screening of individual analytes (e.g. Hapsite, Frog-4000). Furthermore, recent innovations have modified GCs for remote semi-continuous deployment supported by autocalibration and multiplexed autosampling.
Analytical sensor platforms have historically been relegated to research prototypes and uncommercialized yet “market-ready” innovations from the Small Business Innovation Research (SBIR) Program (among others). Given the environmental industry’s slow rate of technology adoption, many of these promising products never found fertile ground for commercialization. That trend seems to be changing as several products have already found market acceptance and others are undergoing field testing. As follows are three platform technologies that are beginning to have market penetration.
VaporSafeTM VI Monitoring
An innovative VOC monitoring service out of California (VaporSafeTM) is blazing new trails in temporal-spatial monitoring of vapor intrusion. VaporSafeTM deploys a telemetry-enabled portable GC platform modified with a multiplexed autosampler to enable automated processing of indoor air (or soil gas) samples from up to 30 locations with the ability to hold calibration for months of continuous monitoring. Long term calibration is ensured by dedicating a sampling port to a NIST-certified gas standard. Equipped with an Electron Capture Detector (sensor), this system can be configured for near-continuous detection of TCE, PCE, DCE, VC and other common VOCs with detection limits at or below 1 ug/M3 (following modified EPA Method TO-14). Given the relationship VI concentrations have with pressure dynamics, VaporSafeTM also includes capabilities for monitoring pressure differential, barometric pressure, and indoor pressure.
Deployed with telemetry, customers can receive emailed reports and access a live data portal (Hosted by Groundswell Technologies, Inc.) with automatically-rendered data visualizations. The reporting dashboard offers time-series plots, contouring, time-weighted averaging, automated threshold alerts, and daily status summaries. Data is also accessible via Excel spreadsheet and image captures.
VaporSafeTM System Deployed at an Industrial Site
Applications: The VaporSafeTM system offers three modes of operation which support multiple industry monitoring applications.
- In “Check” mode, the system offers VOC screening capabilities to support VI due diligence by allowing same-day testing of grab samples to determine whether a VI issue exists, identify locations (rooms) of concern, and to establish sampling stations for extended or continuous monitoring.
- In “PinPoint” mode, dedicated continuous monitoring points are established by installing sample conveyance tubing from the GC platform to desired locations up to 300 meters away. Once deployed (with telemetry), no personnel are required onsite until the customer’s continuous monitoring needs are met. As the name implies, “PinPoint” mode supports identification of vapor entry points, profiles concentration dynamics (temporal-spatial), allows real-time “cause & effect analysis”, helps distinguish between intrusion and indoor sources, and automatically delivers alerts to key personnel. “PinPoint” mode is also designed for short term (e.g., a few days to weeks) deployments for due diligence and to verify clean conditions. Such capabilities are creating a buzz in the VI sector as high-density temporal data sets are answering site-specific questions that have plagued practitioners for years.
- In “Control” mode, VaporSafeTM offers real-time monitoring and control functionality to support mitigation efforts and reduce liabilities. The system can be configured to activate blower controls in response to concentration threshold exceedance or pressure differentials. Control mode has been used at sites to verify and optimize mitigation system performance by allowing real-time cause & effect process adjustments.
For acute TCE exposure concerns, VaporSafeTM has been marketed as a liability management service, as alerts and engineering responses can be engaged within seconds of a risk detection. However, their system is not limited to continuous monitoring deployments. Since the system can be actively monitoring within a couple hours of deployment, VaporSafeTM is also being utilized for initial assessments and for episodic monitoring needs to meet quarterly monitoring requirements.
Burge TCE Optrode
Another deployable analytical sensor platform offered by Arizona’s Burge Environmental provides for continuous monitoring of TCE in groundwater. A Colorimetric Optrode is used to measure headspace TCE concentrations based on its natural diffusion across a membrane from a water sample. This fully automated system can be wall-mounted for continuous monitoring of industrial/municipal treatment facilities or deployed at remote locations for monitoring surface or groundwater. Groundwater, surface water, or process water samples are delivered to the system via direct pressure (process), peristaltic pump, or centrifugal pump.
Remote installations are configured with solar power, wireless communication, and process controls that can activate relays based on preset concentration exceedances. The system is configured with 4 sampling ports and a pre-programmed quality control system that performs QC checks (duplicates & matrix spikes) to ensure reliable TCE results down to 5 ppb. The TCE Optrode platform can also be configured to monitor secondary parameters like pH, conductivity, ORP, water level, temperature, and others. Burge offers similar systems that target Carbon Tetrachloride, Hexavalent Chromium, 90Sr, Uranium, Technetium, Methane and other analytes.
Optrode Deployment at Columbia River Location, WA
Customers can receive emailed reports or access a live data portal (Hosted by Groundswell Technologies, Inc.) with automatically-rendered data visualizations. The reporting dashboard offers time-series plots, contouring, time-weighted averaging, threshold alerts, and daily status summaries. Data is also accessible via Excel spreadsheet and image captures.
For gas monitoring applications, Ireland-based AmbiSense offers the GasfluXTM system providing remote continuous measurements of gas concentrations and flow. Common parameters monitored include CH4, CO2, O2, CO, H2S, pressure, flow, and weather conditions. The system can also be adapted to measure other air quality sensors (NOx, SOx, particulates, ammonia, etc.) and equipped with a PID sensor for monitoring total VOCs. Being telemetry-enabled, their system supports real-time, continuous evaluation of landfill gas dynamics to replace traditional approaches that rely on manual or spot measurements requiring many site visits. As with vapor intrusion dynamics, continuous monitoring capabilities can reveal highly dynamic temporal variation in gas concentrations and flux driven by diurnal changes in barometric pressure, promising new insights about subsurface gas behaviors and improved risk assessment. Continuous monitoring of ground gas has revealed that risk assessments based on limited datasets that ignore these dynamics tend to result in highly conservative conclusions which can unnecessarily increase the cost of compliance and mitigation efforts.
The GasfluXTM monitoring results can be used to estimate gas permeability by measuring and analyzing the pressure amplitude and phase lag. The permeability can in turn be used to estimate surface emissions. Other applications include extraction system optimization, biodegradation assessment, brownfield redevelopment, and landfill permit compliance support. GasfluXTM has demonstrated market adoption in the United Kingdom and Australia and plans to be released to the North American market in early 2018.
Given the current state of interconnectivity offered by the internet and smart devices, we might expect the traditional fixed-based laboratory testing methods to continue to migrate to the location of measurement (job sites). Emerging sensor technology and automated analytical platforms will continue to improve and become more affordable to a point where professional focus will be on large temporal datasets rather than unit sample results. As regulators, RPs, and environmental professionals begin to recognize the efficiencies and improved insights offered by high density temporally-relevant spatial data, we can expect increased technology adoption and new product offerings in the marketplace.
In future articles, I will highlight some of the key wireless sensor network options and cloud-based monitoring data platforms that facilitate dissemination of environmental data.
Brian M. Kahl, PG