LMC § 10.20.110 sets dB(A) ceilings measured at least 25 feet from the source: residential 50 night / 55 day, commercial 55 night / 65 day, industrial 75 day and night. Mixed-use dwellings on a non-residential lot are treated as commercial.
Table 10.20.110 A (Nighttime, 10:00 p.m.–7:00 a.m.): Residential 50 dB(A); Commercial 55 dB(A); Industrial 75 dB(A). Table 10.20.110 B (Daytime, 7:00 a.m.–10:00 p.m.): Residential 55 dB(A); Commercial 65 dB(A); Industrial 75 dB(A). All measurements use the 'A' weighted sound pressure level (dB(A)) taken with a sound level meter using the A-weighting network, at least 25 feet from the source. Subsection (C) clarifies that residential units in the same building or on the same lot as a nonresidential use are 'commercial' for the daytime table (max 65 dB(A)). Subsection (E) applies the most restrictive zone limit when a source can be measured from more than one zone. Defenses include 'condition of emergency' and 'manifest necessity' (subsection (F)(4)); a temporary hardship permit up to 90 days is available from the city manager under subsection (G).
General Longmont Municipal Code penalty: up to $999 fine and/or up to 180 days jail per violation.
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