*September 13, 2021
A stack test is measurement of emissions to the air - sometimes also referred to as a performance or source test. Stack tests utilize EPA-approved test methods and are designed to measure the amount of a specific regulated pollutant, group of pollutants, or surrogates for pollutants being emitted from a stack or other emission point at a stationary source. A source can be an individual piece of equipment like a boiler, a process, or a group of equipment whose emissions are routed to a common emission point or points.
Stack testing gives us pollutant specific emissions data for emissions over a certain period of time. During a stack test, other data relating to the source and/or pollution control device(s), such as stack gas flow, gas temperature, and moisture content, are collected to have the information necessary to evaluate the results of the test. The additional data is used to calculate emissions rates for comparison to different operating conditions, fuels, and processes. This information also enables the Department to relate the measured emissions with the process operating status and conditions during the test.
The stack testing should be representative of normal operations, but also when maximum emissions are expected – maximum production and highest emission fuel - so that the maximum quantity of the pollutant being measured would be produced during the test. It is important to note that most facilities do not routinely operate at these worst-case conditions year- round, so the actual emissions during normal operations are usually less than measured during a stack test.
Stack testing frequency is usually determined by the state or federal regulatory requirements relevant to the source being tested. DHEC may require a specific stack testing frequency or additional testing for a source as a condition of an air permit or through an order outside of regulatory testing requirements.
Stack tests are generally conducted by third-party environmental testing contractors who have expertise in stack testing and utilize specialized testing equipment designed to measure specific pollutants. The specifications of testing equipment have been standardized within the EPA-approved testing methods, other approved methods allowed by regulation, or otherwise approved by the state or federal regulatory agency. The testing is performed pursuant to an approved testing protocol and is observed by DHEC staff.
In most cases, specialized probes connected to instruments or samplers are inserted into the stack to direct the gas to instruments for immediate measurement or to collect samples for later analysis.
The testing contractors set up the testing equipment according to the test methods and requirements in the approved test plan and verify the equipment is properly calibrated. Then, these contractors extract stack gasses using methods that depend on pollutant being tested and specific equipment being utilized.
A typical stack test consists of a minimum of three test runs of at least one hour in duration each. The results from each run are then averaged to determine the test result.
Stack test data can be used to:
- Determine compliance with emission limits,
- Verify emissions factors used in models and estimates used for permitting,
- Establish or verify operational ranges of various sensors or devices used to monitor and document the source operation,
- Establish or verify pollution control device efficiency,
- Verify accuracy of continuous emissions monitors required by the process or in permits, and
- Provide a basis for required emissions reporting.
Some sources emit pollutants that do not go through a stack or other emissions point. In that case, stack testing equipment and procedures cannot be used to quantify those emissions. However, other compliance methods, such as visible emissions readings, inspections logs, and record keeping are typically used to determine compliance.
For example, for the New Indy stack tests, some emissions were directed through stacks that were specifically designed and installed to allow measurement of emissions that otherwise would have had to be estimated.
All facilities are required to submit a test protocol or plan to DHEC for approval prior to testing. Technical staff review the plan to ensure the correct test methods and procedures are utilized in accordance with the state or federal requirements, permit conditions or an order. The test plan must be approved before testing begins. The facilities are also required to notify DHEC of test dates so DHEC staff may be present to observe the testing procedures and ensure the plan is being followed.
Most testing can be completed in 1-3 days, but due to their complex nature some tests may take much longer. Factors impacting the time required to conduct testing include the number of sources being tested, the number of sampling locations on those sources, the number of different pollutants being tested, the required test methods and associated analytical and laboratory work, testing and safety procedures, and operating conditions of the plant at the time of the test. Often the reports generated are several hundred pages, so additional time is required to review the test data prior to using it to make any regulatory decisions.
After a report is received, DHEC reviews the data and calculations for accuracy and completeness. The testing program is evaluated for adherence to the test plan including applicable regulations, test methods, and other requirements. If errors or missing data is discovered, the facility and testing contractor is notified of what revisions are required to enable the report review to be completed. Once all concerns have been addressed, a draft report summary is written by the DHEC project manager that includes the information gathered from the testing event. This summary report goes through an internal review process and once approved, it is provided to the facility.
A Phase 1 site assessment is a review of the current and historical uses of property to see if those activities have impacted the soil or groundwater and if those impacts could pose a threat to the environment and/or human health.
A Phase 1 Environmental Site Assessment was conducted as part of the real estate transaction.
Our periodic monitoring assessment reports have indicated localized groundwater impact by petroleum and cleaning solvent constituents, and metals at low concentrations at various locations on the plant property. There is no evidence of contamination leaving the property in groundwater.
Public drinking water in the area comes from the Catawba River at a location upstream from New Indy.
All private wells identified in a well survey are either located:
- on the opposite side of the Catawba river, which serves as a barrier to groundwater flow, or
- or in areas before groundwater flows under the facility
The available data and information do not suggest a potential risk of impact to drinking water sources.
Assessment and Corrective Action
The federal “superfund” program has many facets and authorities. The team EPA sent to help with air monitoring is housed in the superfund program and they acted under the authorities the federal superfund program provides to be able to assist with the air monitoring. New Indy is not a listed federal Superfund site (also known as a National Priority List (NPL) site.
The VCOC provides for Department oversight of the environmental assessment of the property and the subsequent corrective actions taken based on the assessment results. The Department entered into a Voluntary Cleanup Oversight Contract (VCOC) with New-Indy Catawba, LLC, for the Bowater-Catawba Pulp site on December 21, 2018.
The cleanup covered by the VCOC includes the necessary response actions to address dioxin-containing sludge at the site. The subject of this contract is limited in scope and is not related to offsite odors.
The contract is voluntary in the sense that it is not required and can be terminated by New Indy. If they elect to terminate, the company must certify that the site doesn’t pose a new health or environmental hazard that did not exist prior to response actions initiated under the VCOC.
It has not been completed to date and is ongoing.
Any non-compliance with the terms of the VCOC could be cause for termination of the contract in which case any protections afforded therein would be terminated.
The site will continue to be monitored after the VCOC is completed.
The objective of the contract and the process is to ensure that the risk of exposure to the public is minimized. New Indy will be required to prevent any migration of chemicals covered under the VCOC offsite and to clean up any offsite release of contaminants.
The offsite (community) and onsite (fence line) monitors operated by EPA, DHEC and New-Indy operate 24 hours a day, 7 days a week. The EPA community monitoring ended June 30 at which time a third-party contractor hired by New-Indy began collecting and reporting data. DHEC also has a monitor in a community and data is posted to our webpage daily.
There may be short periods of time when a monitor will be offline for maintenance, operational checks or repair, but monitors are expected to be operating through the night and over weekends and holidays. If there is a significant period of missing data, it will be indicated in the daily reports.
EPA had evidence that operations at the New Indy Facility were emitting hydrogen sulfide into the air at concentrations measured offsite that, if allowed to continue, posed an imminent and substantial endangerment to public health, welfare or the environment.
Hydrogen sulfide is one of a class of chemicals emitted by Pulp and Paper Mills referred to as Total Reduced Sulfur (TRS) that may create strong odors. The main four chemicals in TRS are:
- Hydrogen sulfide
- Methyl mercaptan
- Dimethyl Sulfide
- Dimethyl Disulfide
The odor reports from citizens since mid-March overwhelmingly describe an odor like rotten eggs, an odor most associated with H2S.
Methyl mercaptan is described as a gas odor because most people associate it with natural gas. Natural gas is odorless. Methyl Mercaptan is added to natural gas to alert people to gas leaks. Gas-like odors have been infrequently been reported.
Dimethyl Sulfide and Dimethyl Disulfide may have a cabbage smell.
The DHEC order and EPA Information Request letter required New Indy to perform testing for all four of these TRS pollutants during the Stack Testing.
If you have gas appliances, you have methyl mercaptan (or another chemical odorant) in the gas that is in your home. There is a reminder on our web page that any gas-like odor, especially indoors, should be taken very seriously as it could represent a gas leak that would pose immediate and significant safety concerns to building occupants.
The EPA’s GMAP report compared H2S results to the ATSDR Acute Minimal Risk Level (MRL) of 70 parts per billion. In a footnote on page 2 they say, “MRLs are intended to serve as a screening tool to help public health professionals decide where to look at a pollutant more closely. To be protective and conservative, ATSDR sets MRLs below levels that, based on current information, may cause adverse health effects. Exposure to a level above the MRL does not mean that adverse health effects will occur. Rather, it indicates the need to investigate the situation more closely.”
Exposure guidelines have two components: concentration and time. Both components are part of how safe levels are established to be protective.
The monitors closest to New Indy have reported concentrations of H2S above the ATSDR Minimal Risk Level (MRL) of 70 ppb. However, in all cases to date, the elevated concentrations have been for short periods and the 24 hour average concentration used for comparison to the level of the MRL has not approached the level of the standard.
The DHEC daily report provides both the rolling 24 hour average and the average for the report period (midnight to midnight). The rolling 24-hour average is calculated continuously and is shown on the daily report graph.
The calculation does not start over each day. For the DHEC daily reports, the average for the period is displayed report table.
There are two types of air monitoring being done – each to meet different, but overlapping objectives.
Both onsite (fenceline) and community monitoring help ensure that concentrations of H2S are maintained at concentrations that are below established levels of concern.
EPA required New-Indy in their Order and Information Request letters to establish and operate three fenceline monitors and a network of community monitors.
EPA operated community monitors from May 13th to June 29th. New-Indy has operated community monitors since June 30th and is required to continue monitoring and reporting for one year.
DHEC has also been operating monitors to supplement the New-Indy fenceline sites and collocated with one of the New-Indy community monitors
The Community Monitoring conducted by EPA, New-Indy and DHEC has consistently shown that concentrations are below the level of the ATSDR Acute Minimal Risk Level (MRL) of 70 parts per billion over 24 hours.
Although some concentration peaks do occur that are above the level of the MRL, they have typically been of short duration and the average exposure has not gotten close to the MRL.
To be protective and conservative, ATSDR sets MRLs below levels that, based on current information, may cause adverse health effects at that concentration over the indicated period of time. Exposure to a level above the
MRL does not mean that adverse health effects will occur. Rather, it indicates the need to investigate the situation more closely.
The onsite, or fenceline monitors, often indicate concentrations that are higher than detected by the community monitors. This is expected since they are closer to the sources. That monitoring has indicated a decrease in concentrations of H2S over time.
The fenceline monitors nearest the sources can provide the clearest and most immediate indication of problems and processes that contribute to emissions. Concentrations are higher and, are detected more quickly and can prompt a response that can minimize offsite impact. Analysis of the fenceline data can also reveal sources that may not have been considered.
For example, on the evening of June 4th a significant spike in H2S concentration at New-Indy’s station 1 prompted a rapid response, investigation, and identification of an immediate source (post aeration basin), planning and implementation of mitigation (cover and charcoal scrubbing) and planning for a permanent corrective action. The onsite monitoring prompted a rapid response to an unexpected source of emissions, application and evaluation of an immediate corrective action to one emissions point and longer term response and corrective actions that are reducing emissions from an area (Holding Pond #1)that had not previously been identified as a contributor to emissions.
Ambient air monitoring strategies consider objectives, resources and capabilities. In this case, we are trying to assess the potential risk over an area of more than 300 square miles. The relatively large number of monitors that EPA provided and the ability to have near real time access to the data provided capability and resources that is unprecedented in South Carolina.
Each monitor represents concentrations across a community. There will be areas of higher and lower concentration at any particular moment, but over time a monitor that is placed to have clear air flow will provide a measurement that is representative of concentrations in the area. In general, monitor placement will follow the requirements EPA has established for ambient monitor siting.
The objective of the community monitoring has been to measure representative concentrations where people have reported impacts. The communities and locations were selected based on prevailing and expected wind, concentrations of residents that have provided reports, and the availability of suitable, specific locations within those communities to place monitors.
If the monitoring objective was only to capture highest concentrations, the monitoring network would look very different. The EPA-ordered fence line monitors and some other monitoring EPA and DHEC have conducted serve that and similar objectives.
The community monitoring provides a quantitative indicator of community impact that can be compared to health-based guidance, help identify conditions that may increase the burden and provide a measure of the effectiveness of changes at the source. It is only one point and all individual’s experience will be different, but over the months of data collection we have gained better understanding of the concentration range, duration, and the extent of the impacts.
The ATSDR Acute Minimal Risk Level (MRL) of 70 parts per billion intended to serve as a screening tool to help public health professionals decide where to look at a pollutant more closely. To be protective and conservative, ATSDR sets MRLs below levels that, based on current information, may cause adverse health effects. Exposure to a level above the MRL does not mean that adverse health effects will occur.
The level is set based on exposure to an average concentration at or above the level for 24 hours.
To date, no community monitoring results have approached the 70 ppb ATSDR Minimal Risk Level for 24 hours. There must be significantly higher concentrations detected to exceed other, shorter time period exposure guidelines. For instance, the AEGL-1 for 10 minutes is 750 parts per billion.
Acute Exposure Guideline Levels (AEGLs) represent threshold exposure limits for the general public and are applicable to emergency exposure periods ranging from 10 minutes (min) to 8 hours (h). Three levels—AEGL-1, AEGL-2, and AEGL—are developed for each of five exposure periods (10 and 30 min and 1, 4, and 8 h) and are distinguished by varying degrees of severity of toxic effects. AEGL-1 is the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic, nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure.
DHEC has been in close communication with local public drinking water suppliers to the area. The intake for drinking water systems supplying the neighborhoods in the area is UPSTREAM from the New Indy discharge. The nearest downstream drinking water intake is 9 miles downriver. At this time no issues have been identified that are affecting drinking water quality.
DHEC routinely conducts ambient water quality monitoring on rivers and reservoirs across our state. (See this link for information on our ambient monitoring.) DHEC has worked with the Catawba Riverkeeper to conduct a special study on the river, looking at upstream and downstream locations relevant to New Indy. A report has been issued and is posted here.
On-site inspections of the facility by either DHEC or EPA will follow the normal inspection processes for each agency. The processes include on-site visits, reviews of documentation, notices of alleged violations, enforcement conferences, reports and appeal processes. Once finalized, any enforcement actions will be publicly available and linked from the New Indy Reports & Documents webpage.