Why doesn’t the town require a Regenerative Thermal Oxidizer (RTO) be installed to control plant emissions? UPDATED 11/13/2023

Staff has inquired about this technology with our consultant, Ninyo & Moore. It was explained to us that RTO technology is not intended for this type of plant. It is meant for much larger plants with greater emissions, such as power plants. If applied to a hot mix asphalt plant, the consultant stated that it could worsen emissions. Instead, staff has been researching other technologies that are more appropriate for asphalt plants and which serve the purpose of reducing emissions. 

11/8/2023 Update: Staff has reached out to our consultant for additional information on RTOs as may be implemented in the manufacture of asphalt. We were provided with examples of RTO technology that had been used at asphalt shingle manufacturing facilities. We are not aware of any examples of this technology being used in a hot mix asphalt plant such as is being proposed on this site. Our consultant explained that the potential worsening of emissions with an RTO system is caused by the additional fuel used (natural gas, propane, used oil, etc.) to power the RTO, and the additional CO2 and N2O emissions are not controlled by the system. Literature suggests that the system might be self-sustaining under certain conditions, but this manufacturer claim has not be evaluated. Instead of a RTO system, staff will likely recommend a blue smoke eliminator system, which is industry best practice for reducing emissions. 

11/13/2023 Update: Our consultant has provided further information about the difference in asphalt shingle manufacturing vs asphalt batch manufacturing to help explain why the RTO, while it may be appropriate for an asphalt shingle plant, is not necessarily the best technology for a HMAP.

  1. Asphalt shingles are made in large lots or continuous manufacturing processes for outbound shipment to distributors and home improvement stores, whereas asphalt paving is done in small “batches” depending on daily demand or local orders pending. An air quality control device that runs 24/7 might be suitable for a large manufacturer with continuous operation, but may not be suitable for operations that start and stop on a daily basis, like an Hot Mix Asphalt (HMA) batch plant.
  2. Asphalt shingles manufacturing requires an “asphalt blowing” process for asphalt saturants and coatings, where air is passed through the hot oil, and this requires control of more process airflow than a typical HMA storage silo and counter-flow drum mixer.
  3. Asphalt shingle manufacturing and HMA plants have separate research studies and emission factors, and are regulated differently by the EPA.  
    1. Per EPA AP-42, Section 11.2, Table 11.2-4, Asphalt shingle manufacturing has at total organic compound (TOC) emission of 1.3 lbs./ton of saturant asphalt, and 3.4 lbs./ton of coating asphalt, as well as additional EFs for other steps in the manufacturing process (shingle saturation, etc.).
    2. Per EPA AP-42, Section 11.1, Table 2 (EPA 454/R-00-019), HMA plants have a total volatile organic compound (VOC) emission factor of 0.050 lbs./ton of HMA produced, which is roughly 1% of the TOC emissions produced by the two “asphalt blowing” processes in asphalt shingle manufacturing.

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1. Why didn’t the town just dismiss the application outright?
2. Has the town already made up its mind to approve this?
3. Why is this taking so long? UPDATED 12/4/2023
4. Why is the Town allowing Vulcan to provide their own studies?
5. If the town decides to approve this, can extra requirements be placed on Vulcan?
6. What is a General Plan?
7. How does the General Plan work in conjunction with the zoning code?
8. How does the Town determine compliance with the General Plan?
9. How can the Town consider approving this application when so many residents are against it?
10. How can this use be allowed when the purpose statement of the RH zone is “to preserve the character and encourage the orderly growth of rural areas in the town."
11. What about the single access to the site crossing the railroad? Isn’t Union Pacific concerned? What about fire access? UPDATED 11/8/2023
12. Why is the town not requiring an EIS?
13. Why doesn’t the town require a Regenerative Thermal Oxidizer (RTO) be installed to control plant emissions? UPDATED 11/13/2023
14. Traffic volumes – how will this affect my daily drive? Won’t this cause undue wear and tear on Old Nogales Highway? UPDATED 11/20/2023
15. Are the emissions going to make me sick?
16. Why can’t the town regulate environmental permits?
17. I heard that the Vulcan property is classified as vacant for tax purposes. Doesn’t this negate their claim that the sand and gravel operation is a legal nonconforming use? UPDATED 11/8/2023