1200 INDUSTRY ST EL DORADO STONE 2018-05-21

Paul Barron.P.E. H E/�D W/�T E R S Regionul Environmental Manager $]S Maurice Drive Cedar Park,TX 78613-4090 Phone: (512)�35-6323 Mobile: (512)560-6763 Fa.r (S l2)535-5533 E-mail: pharron@headwaters.com May 30, 2014 Ernest Stellingwerff Plant Manager 1200 Industry St Everett,WA 99357 RE: Emission Based Exemption (WAC 173-400-110(5)) Dear Mr. Stellingwerff: The purpose of this letter is to provide onsite documentation of the fact that Eldorado Stone, LLC is claimin� an emission based exemption for the manufacturing of cultured stone molds silo located at its Everett,Washington facility. This exemption is claimed on the basis of Regulation I Section 6.03(b)(l0) for the injection molding and spray booth and Section (c)(1) for the direct natural gas-fired air make-up unit. The Eldorado Everett facility manufactures the molds that are used for manufacturing architectural and decorate cultured stone products. All manufacturing oecurs in a single manufacturing building that is ventilated by filtered exhaust systems at the spray booths. Open- ended plywood boxes (farms) are assembled on site. The forms are then treated with polyurethane foam, followed by latex molds. The outside of the forms are then treated with a polyurea treatment for rigidity and added longevity of the product. This exemption claim for the injection molding and spray booths is based on two separate sections of PSCAA's Regulation I. Section 6.03(b)(10) provides that exemptions may be b anted on a case-by-case basis if it is clearly demonstrated that a proposed project has "de �nini�fiis impact on air quality and cloes not pose a threat to human health or the environment". It is this section of Regulation I that applies to the injection molding booth and the process emissions generated by injection molding because of the very low level of MDI (a VOC) emitted. Section 6.03(c)(1) provides the categorical Order of Approval exemption for gas-fired combustion equipment having a rated capacity less than 10 MMBtu/hr. This exemption applies to the ancillary air makeup unit that accompanies the booth. As shown in the attached emission calculation spreadsheet and SCREEN3 modeling results, the emissions of 4,4'-diphenylmethane diisocyanate or MDI represent an ambient concentration of 0.006 µ�/m3 (1-hour average of 0.014µg/m3 multiplied by a persistence factar of 0.4 for the 24-hour average), or approximately one order of magnitude less than the Acceptable Source Impact Level (ASIL) of 0.2 µg/m� provided in Appendix A of Regulation III. We therefore submit that the emissions and corresponding ambient concentration of MDI are insignificant with minimal potential impact on human health and the environment and a permit should not be required. Therefore, Eldorado Stone Operations, LLC is claiming an exemption for the injection molding and spray booths at the Everett facility. :- 1�;�,