Notes
Technical memorandum from Harris Miller Miller & Hanson Inc. (HMMH), authored by Eric Cox, to Julie Kinzie at Seattle-Tacoma International Airport (SEA), reporting acoustical testing results for the SEA Repair and Replacement Program conducted September 2025. HMMH measured median interior Day-Night Average Sound Level (DNL) values for 29 residential structures in SeaTac and Burien using a Hottinger Brüel & Kjær (HBK) Model 2245 sound level meter and Mackie SRM450 loudspeaker, per FAA Advisory Circular AC 150/5000-9B Chapter 8 and FAA Order 5100.38D Appendix R. Noise Level Reduction (NLR) was calculated using Boeing 737-800 aircraft noise spectrum against a 70 dB exterior DNL from the 2018 Forecast Condition Noise Exposure Map (NEM). Results show no structures meet the 45 dB median interior DNL threshold for sound insulation eligibility, but 10 structures have individual habitable rooms exceeding 45 dB interior DNL. Addresses tested include 10th Ct S SeaTac, 12th Pl S SeaTac, 13th Ave S SeaTac, 14th Ave S Burien, and 14th Pl S Burien. HMMH Project Number 03-12150.001.004.