10 Questions for Metalcasters on Fine Particulates

The regulation of particulate matter may have a significant impact on newly built or updated metalcasting facilities.

AFS Air Quality Committee (10-E). Principal Authors: Tom Rarick and Daniel Guido, ERM, Carmel, Indiana

(Click here to see the story as it appears in the August issue of Modern Casting.)

MODERN CASTING last discussed the regulation of fine particulate matter (PM) and the implications for metalcasting facilities in July 2012. In the past three years, a number of developments have occurred, including the lowering of the annual standard. This article provides updated information and perspectives on this topic, which may have significant consequences for metalcasters wanting to expand and modernize their facilities.

1. What is PM2.5?

PM2.5 consists of solid and liquid particles that are equal to or smaller than 2.5 microns, which is approximately 30 times thinner than the diameter of a human hair. These fine particles can be emitted directly from a metalcasting facility or can form as a result of gaseous emissions that condense to form particles downstream. As such, when PM2.5 is evaluated, both filterable (solid) particulate is measured as well as condensable particulate matter (CPM).

2. How are PM2.5 emissions from metalcasting sources estimated?

Accurately estimating PM2.5 emissions from metalcasting sources is important because these estimates are used:

  1. To determine whether certain rules may apply.
  2. As the basis for enforceable emission limits.
  3. As the basis of air quality assessments.
  4. To predict the ability to comply with enforceable limits.

Estimates can be based on general emission factors or preferably on stack test data. A limited amount of data is available for use in estimating PM2.5 emissions from most metalcasting sources. In addition, emission levels have considerable variability, especially for CPM. The U.S. Environmental Protection Agency (EPA)’s “Compilation of Air Pollutant Emission Factors” (or AP-42) is of limited help since most of the emission factors are for total particulate matter. Limited data exists on the size distribution of PM to allow for accurately estimating the PM2.5portion. Lastly, none of the factors for foundry processes include the condensable portion of the emissions. As a practical matter, estimating emission levels can be a fairly complex process of selecting the best data available and also assessing the potential variability of emissions and its impact on the specific regulatory use of the emissions estimates.

3. How do you measure PM2.5emissions from your facility?

EPA has specific test methods for measuring both filterable PM2.5 emissions (EPA Method 201A) and CPM (EPA Method 202). Method 201A measures the weight of the solid or liquid particles that are captured on a filter (after the particles larger than 2.5 microns are segregated out). Method 202, the specified method for measuring CPM, is applied downstream of the filter and measures condensed materials that may have passed through the filter. The combined result of these two methods is reported as the total PM2.5 value.

4. What are the principal PM2.5 emission sources at metalcasting facilities?

The emission sources with the largest PM2.5 emissions at typical metalcasting facilities include melting, sand handling, pouring, cooling and shakeout. Filterable emissions from these processes can be significantly reduced using fabric filters or high efficiency wet scrubbers. CPM emissions are not effectively controlled by baghouses and can be significant, especially from the pouring, cooling and shakeout processes where they can be much more prevalent than the controlled filterable emissions. Other smaller emission sources also contribute to total PM2.5 emissions including material handling processes, natural gas combustion, diesel engines, scrap pre-heaters and emissions from roadways.

5. What national ambient air quality standards apply to PM2.5?

Table 1 summarizes the current PM10 and PM2.5 National Ambient Air Quality Standards (NAAQS), which are expressed as a concentration in micrograms per cubic meter (µg/M3).

The PM2.5 annual standard was lowered from 15 µg/M3 to 12 µg/M3 in March 2013. In December 2014, EPA designated 38 counties in six states as nonattainment. States will be required to submit plans for these non-attainment areas in 2018 that must provide for attainment by 2020. EPA projects that most areas will be able to meet the new standards based on implementation of federal rules on power plants and diesel engines and that only a few areas will be required to adopt rules for specific sources such as metalcasting facilities.

6. Which metalcasting facilities will be subject to PM2.5 limits?

Most metalcasting sources do not have PM2.5 limits now, nor will such limits likely be established unless the facility is modified or replaced. Limits may be established through rules promulgated by states to meet air quality standards, but these will be rare for metalcasting sources. Generally PM2.5 limits are established through permitting requirements to either

  1. Limit annual emissions below thresholds that would subject a project to the review under either the Prevention of Significant Deterioration (PSD) or Non-Attainment New Source Review (NNSR) rules.
  2. Establish limits as either Best Available Control Technology (BACT) under the PSD rules or Lowest Achievable Emission Rate (LAER) under the NNSR rules.

The most common technology for meeting these requirements is the use of a highly efficient fabric filter baghouse and the limits would include both filterable and condensable particulate matter.

7. Will new PM2.5 emission sources trigger PSD or NNSR permit requirements?

The PSD and NNSR permitting rules apply to projects where the increase in emissions from the project is expected to exceed certain thresholds. If a location is already a major source under either of these rules, an emissions increase of only 10 tons/year of PM2.5 would be required to meet the technology and air quality impact requirements of these rules. Sources can limit emissions from new and modified sources to less than 10 tons/year to avoid being subject to these rules through enforceable permit limits. If subject to the PSD rules, the project would be subject to the BACT technology requirement as well as the requirement to demonstrate that the project would not result in exceedances of the air quality standards or PSD increments. The air quality assessment requirement may pose the biggest challenge for projects subject to the PSD rules. For new and modified sources in non-attainment areas, the NNSR rules require the use of LAER level controls and for sources to obtain offsets from third parties for any emission increases associated with a proposed project. If a project is subject to either the PSD or NNSR requirements, the time frame for obtaining a permit can extend from four months to a year or more.

8. Why is air modeling for PM2.5 under the PSD rules a problem?

Under the PSD rules an air quality model is used to predict the ground level concentrations of PM2.5 associated with the project. The model required under the PSD rule is the AERMOD model that has undergone several modifications since late 2013. The two basic analyses required are an evaluation to demonstrate that the project will not result in an exceedance of the PSD increment and the project plus background air quality levels plus impacts from other nearby sources in the area do not exceed the NAAQS. The PSD increments for PM2.5 are 9 µg/M3 for the 24-hour standard and 4 µg/M3 for the annual standard. Lower increment values are used for sources that may construct near Class I areas, which include a number of National Parks. The “increment assessment” may be the limiting analysis, especially for greenfield metalcasting facilities

For modified sources, the limiting assessment is more often the NAAQS assessment where the modeled value for the source is added to the background air quality value (from a representative monitor) as well as impacts from other significant sources near the project site. Typical background values for the 24-hour standard may range from 23 to 31 µg/M3, leaving very little room for new sources of PM2.5  since the standard is 35 µg/M3. The recently lowered annual standard of 12 µg/M3 may pose an even greater challenge with background levels at or above 11 µg/M3 in some areas. Attainment has not been possible to achieve for a number of projects, which either have been shelved or the facilities are continuing to try to find ways to accommodate the specific modeling challenges.

The air quality assessments carried out under the PSD permit rules are governed by EPA modeling guidance, which was most recently updated in May 2014. One change in this guidance is that the eighth high (98th percentile) modeled value for the 24-hour standard is used rather than the first high value, which will make it somewhat easier to show the standard will be protected. Also influencing how the modeling assessments are carried out are recent court rulings, with the most notable from the Washington, D.C. Circuit Court of Appeals in January 2013 that determined the full air quality assessment could not be avoided merely by showing the impact of the project was below a minimal “Significant Impact Level.”

9. Is it possible to get a PSD permit for PM2.5 for a new or modified foundry source?

The short answer is yes. In many instances it is possible to avoid review under the PSD and NNSR rules by demonstrating that a project is not a “major modification” using various tools in the rules including: comparisons of “actual to projected actual emissions”; netting, wherein the benefits of recent or concurrent emission reductions offset increases; or by applying more effective emission controls. For larger projects that cannot avoid review under these rules, a variety of strategies can be used, including making adjustments to background data to remove the impacts of sources that do not impact the area where the source is located, and/or adjusting the locations of emission sources and the height or exit velocity of stacks.

10. What should metalcasters do to prepare PM2.5 issues?

It is important for metalcasting facilities to understand how the regulatory and permitting requirements may impact the facility. Key questions include:

  • Is the facility (existing or new) a major source under the PSD or NNSR rule?
  • Is the facility located in a non-attainment area or an attainment area that could be reclassified as nonattainment in the future?
  • What are the physical changes the facility may want to undertake in the future and how will those changes impact the overall facility, such as increasing the capacity or throughput of other processes?

Obtaining accurate PM2.5 emission estimates is crucial to making strategic decisions and ensuring the source can comply with possible future limitations. Sources should consider conducting PM2.5 emission testing to fill in gaps in available information especially for CPM.

More than ever before facilities need to budget sufficient time and resources for advanced planning for capital projects. Determining the applicability of the regulations, finding ways of avoiding unnecessary complex requirements and allowing sufficient time to prepare permit applications are key to successful projects.   

ncountering a scenario in which you are forced to suddenly and immediately suspend melting operations for an extended period can be a death sentence for many metalcasting facilities. Small to mid-size businesses are the backbone of the industry, but many do not survive when forced into extended downtime. One disaster-stricken metalcaster, however, found resilience through its own perseverance and a circle of support from peers, friends, suppliers, teams from installation and repair providers, an original equipment manufacturer and even competitors.
Tonkawa Foundry, a third-generation, family-owned operation in Tonkawa, Okla., was entering its 65th year of operation this year when a significant technical failure ravaged the power supply and melting furnaces on January 17. Thanks to the textbook evacuation directed by Operations Manager Carrie Haley, no one was physically harmed during the incident, but the extent of emotional and financial damage, and just how long the event would take Tonkawa offline, was unclear.
Tonkawa’s power supply and two steel-shell furnaces would have to be rebuilt. No part of the reconstruction process could begin until the insurance company approved removal of the equipment from the site. The potential loss of Tonkawa’s employees and customers to competing metalcasters seemed inevitable.
Within two days of the incident, repair, installation and equipment representatives were on site at Tonkawa to survey the damage. Once the insurance company issued approval to begin work, the installation team mobilized within 24 hours to remove the equipment and disassemble the melt deck.
Since the damaged equipment was installed in the 1980s and 1990s, Tonkawa and an equipment services and repair company quickly strategized a plan and identified ways to enhance the safety, efficiency and overall productivity of Tonkawa’s melt deck.
“The most critical issue was for our team to organize a response plan,” said Steve Otto, executive vice president for EMSCO’s New Jersey Installation Division. “We needed to arrive at Tonkawa ready to work as soon as possible and deliver quickly and thoroughly so they could get back to the business of melting and producing castings, and minimize their risk of closing.”
Several years after Tonkawa’s melt deck was originally installed, an elevation change was required to accommodate the use of a larger capacity ladle under the spout of the furnaces. Rather than raising the entire melt deck, only the area supporting the furnaces was elevated. As a result, the power supply and workstation were two steps down from the furnaces, creating a number of inconveniences and challenges that impacted overall work flow in the melt area. Additionally, the proximity of the power supply to the furnaces not only contributed to the limited workspace, but also increased the odds of the power supply facing damage.
The damage to the melt deck required it to be reconstructed. It was determined to be the ideal opportunity to raise the entire deck to the same elevation and arrange the power supply, workstation and furnaces onto one level. The furnace installation company provided the layout concepts, and with the aid of Rajesh Krishnamurthy, applications engineer, Oklahoma State Univ., Tonkawa used the concepts to generate blueprints for the new deck construction. The results yielded a modernized melt system with an even elevation, strategically placed power supply, enhanced worker safety and increased operator productivity.
“Eliminating the steps and relocating the power supply farther from the furnaces was a significant improvement to our melt deck,” Tonkawa Co-Owner Jim Salisbury said.
Within four days of insurance company approval, all damaged equipment had been removed and shipped for repair.
The insurance company required an autopsy on the damaged furnace before any repair work could begin. The forensic analysis was hosted by EMSCO in Anniston, Ala., in the presence of insurance company personnel, as well as an assembly of industry representatives from the companies who had received notices of potential subrogation from the insurance company.
Tonkawa’s furnace was completely disassembled while the insurance company’s forensic inspector directed, photographed, cataloged and analyzed every turn of every bolt on the furnace over a nine-hour workday. The coil was dissected, and lining samples were retained for future reference.
While the furnace sustained extensive damage, it did not have to be replaced entirely.
Structural reconstruction was performed to address run-out damage in the bottom of the furnace, a new coil was fabricated and the hydraulic cylinders were repacked and resealed. Fortunately, the major components were salvageable, and ultimately, the furnace was rebuilt for half the cost of a new furnace.
“The furnace experienced a significant technical failure,” said Jimmy Horton, vice president and general manager of southern operations, EMSCO. “However, not only was the unit rebuilt, it was rebuilt using minimal replacement parts.”
Though work was underway on the furnaces, Tonkawa was challenged with a projected lead time of 14 weeks on the power supply.
When accounting for the three weeks lost to insurance company holds and the time required for installation, Tonkawa was looking at a total production loss of 18-20 weeks. From the perspective of sibling co-owners Sandy Salisbury Linton and Jim Salisbury, Tonkawa could not survive such a long period of lost productivity. After putting their heads together with their furnace supplier, it was determined the reason for the long turnaround on the power supply could be traced to the manufacturer of the steel cabinet that housed the power supply.
The solution? The existing cabinet would be completely refurbished and Tonkawa would do the work rather than the initial manufacturer. This reduced the 14-week lead time to just five weeks.
Tonkawa is the single source for a number of its customers. Although lead-time had been significantly reduced, the Tonkawa team still needed a strategy to keep the single source customers in business as well as a plan to retain their larger customers.
Tonkawa pours many wear-resistant, high-chrome alloys for the agriculture and shot blast industries. Kansas Castings, Belle Plaine, Kan., which is a friendly competitor, is located 50 miles north of Tonkawa. Kansas Castings offered Tonkawa two to three heats every Friday for as long as it needed.
“We made molds, put them on a flatbed trailer, prayed it wasn’t going to rain in Oklahoma, and drove the molds to Kansas Castings. We were molding, shot blasting, cleaning, grinding and shipping every Friday,” Salisbury Linton said.
Others joined the circle of support that was quickly surrounding the Tonkawa Foundry family.
Modern Investment Casting Corporation (MICC) is located 12 miles east of Tonkawa in Ponca City, Okla. Though MICC is an investment shop and Tonkawa is a sand casting facility, MICC’s relationship with Tonkawa dates back years to when Sandy and Jim’s father, Gene Salisbury, was at the helm.
“Gene was always willing to help you out,” said MICC owner, Dave Cashon. “His advice was invaluable for us over the years, so when the opportunity arose to support Sandy and Jim, we volunteered our help.”
 MICC offered to pour anything Tonkawa needed every Friday in its furnace. Tonkawa brought its alloy, furnace hand and molds, while MICC provided its furnace and a furnace hand for three heats. Many of the specialty parts Tonkawa produces were completed with MICC’s support.
When Salisbury Linton approached Cashon and asked him to issue her an invoice to cover the overhead Tonkawa was consuming, Cashon told her if she brought in six-dozen donuts every Friday morning they’d call it even.
“We’re all kind of like family,” Cashon said. “We’re all part of the same industry and though we may be friendly competitors at times, you don’t want to see anybody go through what they’ve gone through and it could have just as easily been our furnace that failed. While we all take the appropriate measures and perform maintenance to prevent these scenarios from occurring, they unfortunately still occur from time to time in our industry.”
Tonkawa had recently added steel work to its menu of services and Central Machine & Tool, Enid, Okla., was able to take Tonkawa’s patterns and fulfill its steel orders so it would not fall behind with those customers, while CFM Corporation, Blackwell, Okla., took three of Tonkawa’s employees on a temporary basis and kept them working during the downtime. Additionally, a couple of Tonkawa’s major suppliers extended their payables terms.
Thanks to Tonkawa’s suppliers, friends and its personnel’s own passion, persistence and dedication, the business is up, running and recovering—placing it among the few shops of its size to overcome the odds and remain in business after facing calamity.
 Nearly eight months after that devastating Saturday evening in January, Salisbury Linton reflected on the people and events that helped Tonkawa rise from the ashes. “We certainly would not have the opportunity to see what the future holds for Tonkawa if it weren’t for all the kind-hearted people who cared about what happened to us. Everyone still checks in on us.”