This is the ambient, at-the-boundary record behind the monitor's hydrogen sulfide page — the concentrations that actually reach the property line, in parts per billion, as distinct from the far stronger in-gas readings inside the wells. A data-quality note: since mid-2025 two of the six stations (MS-2 and MS-5) have reported a flat 0.0 ppb of hydrogen sulfide while their methane sensors keep varying, which points to a non-responsive sensor rather than clean air; the dataset carries the raw values so this is visible.

SubjectArbor Hills Landfill perimeter, Salem Township, Washtenaw County, Michigan (SRN N2688)
What it coversFence-line hydrogen sulfide (ppb) and methane readings from the six perimeter stations (MS-1–MS-6)
Time spanMay 2022 to September 2026
SourceGFL's public perimeter-air feed, operated by Barr Engineering; a raw snapshot is bundled so the enriched table is byte-checkable against the source
FormatCSV, with a raw snapshot and build script
License / costFree to download; underlying data is a public monitoring feed

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