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ARDEN HILLS SPECIAL CITY COUNCIL WORK SESSION — JUNE 23, 2025 3 Baxter shared a graphic showing the location of Building 14 in the upper and west corner of their campus. The property lines of the neighboring homes are less than 100 feet away. Boston Scientific raised the question if something can be done to reduce all of the sources of the noise complaints from neighbors. The goal was to get 5 decibels reduction for the mechanical equipment sources. He thinks a significant amount of noise complaints come from the loading dock area on the north side. That is where deliveries are brought in. The garbage is collected there. It's the place for snow plow activity in the winter. It isn't just the engine noise; it's also the beeping when trucks back up. Mayor Pro Tem Monson asked other than the trucks, where is the equipment located that makes noise. Baxter said there is mechanical equipment on the rooftop. There are some sources on the side of the building, as well. Councilmember Holden said that is a problem for the neighborhood. She pointed out that Boston Scientific are meeting the qualifications now. Baxter confirmed that they are below requirements but they would like the noise levels to be further away from the max limit. Councilmember Weber said the tallest portion of the wall is further down the trail. He asked if the wall will be tall enough on the north side to make an impactful difference. Baxter outlined the topography of the site. He shared a graphic analyzing noise levels. The requirement is they cannot be more than 60 dba during day hours and 50 dba at night. He outlined what the graphic indicated for sound. Councilmember Holden thinks it is louder in the winter. She wondered what time of the year this data was collected. Baxter said these are theoretical calculations, rather than actual measured noise levels. It may sound louder in the winter because it is quieter outside. At this close of distance there probably isn't that big of a difference in the mechanical noise created on the roof regardless of the season. He described how the wall will create an acoustical shadow behind the wall. He said the source of the noise from the roof is from mechanical equipment. Many of them will be replaced in the near future as part of the decarbonization. They will be replacing gas -fired equipment on the roof top and changing of some boilers inside the building to electric. The new units will mostly be in the same location but the newer equipment will have better decibel level performance. Those replacements are already being planned, in advance of this wall. Larson said this includes some of those changes that might happen. We added sources to this graphic that do not exist today. Baxter said when doing an engineering analysis, we want to know what the worst case scenario is and work from there. He explained that the length of the wall on the northern end wouldn't see any added benefit by extending it. They would have preferred to extend it longer in the other direction but a pond and wetland prevent that.