Plain answers to the questions people ask about the Arbor Hills Landfill in Salem Township, Washtenaw County, Michigan. Every answer is drawn from the public regulatory record and labeled with its source. Where a number is the strength of the gas inside the wells rather than what reaches the air, this page says so.
GFL Environmental has owned and operated the Arbor Hills Landfill since October 30, 2020, per the operator's own submission to Michigan EGLE (SRN N2688). Before that it was owned by Advanced Disposal.
Source: operator's EGLE filing (SRN N2688).
It is in Salem Township, Washtenaw County, Michigan, at 10690 W. Six Mile Road, on the border with Northville Township. EGLE's 2023 Materials Management Division consent order (No. 115-05-2023) records the permitted landfill footprint at 337.24 acres.
Land ownership from Washtenaw County parcel records: south of Six Mile Road (the current landfill) GFL owns about 305 acres, and Salem Township, the landfill's host, owns about 164 acres more within the same block. Despite a county assessor class of "industrial vacant," that township land is not empty ground: it lies within the active landfill footprint, with landfill waste on it. North of Six Mile Road, separate from the current landfill and divided from it by Six Mile Road, GFL owns a distinct 251-acre parcel (Section 12) that it has proposed as its expansion area.
Sources: EGLE 2023 Materials Management Division consent order (No. 115-05-2023, 337.24 acres); Washtenaw County parcel records, mapped on the monitor's thermal map.
Yes. Between May 2022 and mid-2025, the six-station perimeter network recorded 56 hourly readings above 30 ppb across 25 distinct episodes. The highest was 327 ppb on June 18, 2025 (station MS-3), about 11 times the 30 ppb fence-line action level, which equals the OEHHA one-hour acute health reference level. Each of these hourly readings clearly exceeds that one-hour reference level; the consent-judgment fence-line action level is a 15-minute rolling standard, so the hourly public feed closely approximates it rather than confirms an exact count. These are ambient concentrations at the property boundary. See the full hydrogen sulfide record.
Data-quality note: the record shows no exceedances after mid-2025, but that recent quiet is not verified. Two of the six perimeter stations — MS-2 (historically the station with the most hydrogen-sulfide exceedances) and MS-5 — have reported a flat 0.0 ppb since mid-2025, while their methane sensors and the other four stations keep varying normally. A working sensor produces small, fluctuating values, not an unbroken run of exact zeros, so this points to a non-responsive sensor rather than clean air.
Source: GFL's public perimeter-air feed (operated by Barr Engineering).
In part because two of the six perimeter stations stopped producing valid data. MS-2 and MS-5 have reported a flat 0.0 ppb since mid-2025, while their methane sensors and the other four stations keep varying normally. A working sensor produces small, fluctuating values, not an unbroken run of exact zeros, so this points to a non-responsive sensor rather than clean air — and MS-2 was historically the station with the most exceedances. The recent absence of exceedances there is therefore not verified compliance.
Source: GFL's public perimeter feed.
In an April 2026 survey of 506 gas wells filed with EGLE, hydrogen sulfide in the extracted gas reached up to 30,000 ppm at a leachate sump (the instrument's ceiling). 261 of the 506 wells were at or above 76 ppm and 91 were at or above 500 ppm; the median well read 80 ppm. These are in-gas source-strength readings: the gas was measured in the sealed collection system, under vacuum, in transit to the flares and RNG plant, a confined-space hazard inside the wells, not what residents breathe.
Source: operator's April 2026 wellhead survey (EGLE, SRN N2688).
The rotten-egg odor is hydrogen sulfide. People typically begin to detect it at about 5 to 20 ppb, and at the Arbor Hills fence line it has reached 327 ppb. The relevant figure for odor and health is the ambient concentration at the boundary and the nearby school (measured in ppb); the far higher in-gas readings (ppm, measured inside the wells) describe the strength of the source before the gas is captured and piped to the flares, not what people breathe.
Sources: GFL perimeter feed; standard hydrogen-sulfide odor-threshold references.
The landfill has a documented elevated-temperature problem across its wellfield, and a localized subsurface event was documented in 2022. The operator's EGLE-filed wellhead temperatures, mapped well by well against the subsurface-temperature-event thresholds, are shown on the monitor's thermal map and wellfield explorer.
Source: operator's EGLE filings (SRN N2688).
On June 16, 2026, EGLE's Air Quality Division walked the landfill surface with methane detectors and recorded 75 areas above the surface-methane action level (500 ppm above background), up to 148,682 ppm at one well. See the inspection record and photographs.
Source: EGLE Air Quality Division inspection, June 16, 2026.
Under an EPA agreement, a 24-hour monitor at Ridge Wood Elementary has reported a hydrogen-sulfide value every month for 68 consecutive months (December 2020 through July 2026), and every one is below 1 ppb — well under the 72 ppb 24-hour screening level. It is a different instrument from the fence-line stations: a 24-hour sampler with a 1 ppb reporting floor.
Source: the Ridge Wood school monitor (operated by Barr Engineering, under the EPA agreement).
Salem Elementary, in Salem Township, is the closest school to the landfill (about 0.6 miles away) and draws its drinking water from its own well — a different school from Ridge Wood above, which is on municipal water and hosts the hydrogen-sulfide air monitor. The school's well is tested for the seven state-regulated PFAS "forever chemicals," and every round on the public record has come back non-detect (below 2 parts per trillion, under the strictest Michigan limit):
| Sample date | All seven regulated PFAS |
|---|---|
| December 8, 2020 | Non-detect (<2 ppt) |
| September 21, 2021 | Non-detect (<2 ppt) |
| March 10, 2022 | Non-detect (<2 ppt) |
| March 14, 2023 | Non-detect (<2 ppt) |
| November 19, 2024 | Non-detect (<2 ppt) |
| February 4, 2025 | Non-detect (<2 ppt) |
Is the testing required? Yes. Salem Elementary is a regulated Nontransient Noncommunity (Michigan "Type II") public water supply, so the PFAS testing is mandated under Michigan's Safe Drinking Water Act (Mich. Admin. Code R 325.10604g, effective August 2020), not discretionary — the clean record is compliance with that requirement.
Two honest limits on scope: the required panel is the seven regulated PFAS, not a full landfill-contaminant scan — 1,4-dioxane, a signature landfill contaminant, has no drinking-water standard and is not required — and the public record of these results runs through February 4, 2025.
Source: EGLE's public water-supply PFAS sampling data (Salem Elementary, WSSN 2001381); Michigan Safe Drinking Water Act, R 325.10604g.
Yes — and because ownership changed partway through, the timeline matters. GFL Environmental took ownership on October 30, 2020.
Under the prior owner (Advanced Disposal, before Oct 30, 2020): per EGLE's own consent-judgment summary, odor complaints from the landfill began in 2016 and continued for years, many cited as nuisance-odor violations. EGLE opened an administrative enforcement action in early 2019 over the odor violations and related Part 55 (air) and Part 115 (landfill-gas control and leachate) violations; unable to reach an administrative settlement, the state filed a lawsuit in October 2020, just before the ownership change. The complaints, the violations, and the lawsuit all predate GFL.
Under GFL (from Oct 30, 2020): GFL acquired the site with that enforcement action pending and became the party bound by its resolution — a March 2022 consent judgment (No. 2020-0593-CE) that imposed a $355,109 civil penalty plus supplemental environmental projects, including the real-time perimeter air-monitoring network. Odor enforcement did not end there: under GFL, EGLE issued a series of nuisance-odor Violation Notices over Cell 6 in October and November 2023, and after inspections found the operator's mitigation fans inadequate, the state issued two stipulated-penalty demands under the consent judgment — $1,500 (January 2024) and $750 (June 2024). The monitor keeps a dated, searchable archive of the EGLE regulatory record. Browse the public records.
Sources: EGLE Consent Judgment Summary (No. 2020-0593-CE) and Violation Notices; Michigan Attorney General.
The operator has submitted a conceptual expansion plan to EGLE for land north of Six Mile Road, and the proposal has drawn community concern. As of September 11, 2026, public comment has not been opened on this expansion plan. Open EGLE public-comment periods and their deadlines for these facilities are tracked on the monitor's public-comment page.
Sources: Michigan EGLE public notices; the monitor's public-comment tracker.
They are two levels of the same corporate structure. Arbor Hills Landfill, Inc. (AHL) is the entity that actually holds the permits and operates the landfill; GFL Environmental Inc. is its parent company and owner. That is why the named party on the consent judgment and the violation notices is "Arbor Hills Landfill, Inc." (AHL), while the owner is GFL Environmental — both are accurate; they simply refer to different levels of the same company. (GFL stands for "Green For Life.")
Source: EGLE regulatory filings (SRN N2688); GFL's November 2020 EGLE ownership submission.
No. Arbor Hills Monitor is an independent, automated project run by a nearby resident. It reads Michigan EGLE's public regulatory record for the Arbor Hills Landfill complex and keeps a dated archive of what it finds. It is not affiliated with the landfill operator, or with the operator's compliance-monitoring vendor at the similarly named arborhillsmonitoring.com.
Source: this project. All underlying data is public regulatory records from Michigan EGLE and other public sources.