Alpena Hide and Leather (Alpena, Alpena County)

• 2017 Site Characterization: PFAS detected in Site soil and groundwater in August and confirmed PFAS detections in groundwater and assessed surface water (Thunder Bay River) in fall. All of the surface water results (14-total) from the Thunder Bay River were below the Rule 57 Surface Water Quality Values (SWQVs) of 12 ppt for Perfluorooctanesulfonic acid (PFOS) and 170 ppt for Perfluorooctanoic acid (PFOA). EGLE also conducted a search to assure that no private drinking water wells are in use in the area.

• Site Characterization: EGLE collected groundwater monitoring well samples in April, June and November. EGLE collected surface water samples from the Thunder Bay River in the spring and fall (all results below SWQVs). Additional samples of foam were also collected, when present in sufficient volume to sample and analyze.
• Benchtop Study - August 2018: EGLE conducted a bench study and treatability study to see if a carbon-based material (Bioavailable Absorbent Media^TM [BAM]) could be added to the soil to reduce PFAS leaching and remove PFAS from groundwater. The results of benchtop studies reduced PFAS in groundwater to levels below SWQVs.
• Groundwater Treatment Pilot Tests - In December 2018, a work plan was prepared and implemented at the Site to evaluate BAM’s ability to treat PFAS in soil and groundwater. BAM was delivered in one test by soil mixing and in another by direct injections into the aquifer. Performance monitoring of groundwater was initiated immediately following the placement of BAM in the ground.

• Community Stake Holder Meetings - February 19, 2019, a meeting with community stakeholders and local governmental agencies was conducted. September 27, 2019, EGLE and AMEC met with the Site property owner to discuss PFAS impacts to groundwater and its relationship to surface water. Remediation/mitigation strategies were discussed as well as future Site development plans.
• PFAS Sample Collection and Analysis - In April, July/August, and December EGLE collected aqueous media samples from groundwater monitoring wells; surface water and foam (when present) from the Thunder Bay River; and storm water from the historical tannery and surrounding infrastructure catch basins.
• Monitoring Well Installation - EGLE installed three new monitoring wells on the Site as well as six new monitoring wells offsite. The wells were used to refine understanding of groundwater flow and were incorporated into the sitewide groundwater sampling program for PFAS.
• Soil Treatment Pilot Test Performance Monitoring – EGLE collected groundwater samples in January, February, April, August and December from wells installed in the pilot test areas to assess BAM performance. At 1-year, PFAS concentrations in the injection area were reduced by 96% to levels below the detection limit (well EW-2). In the soil mixing area, PFAS concentrations were reduced from 39% to as much as 97% (83% for total PFAS; well PZ-2R). Soil samples collected at the 1-year post treatment mark (December) indicated soil concentration reductions for the two primary PFAS detected in soil, Perfluorohexanesulfonic acid (PFHxS) (77%) and PFOS (86%), respectively.
• Storm Water Proof of Concept (POC) Study – On September 27, 2019, EGLE deployed a test boom filled with BAM to assess its utility as a potential cost-effective point source treatment/mitigation of PFAS in storm water. EGLE collected a sample of storm water up- and downstream of the boom on October 2, following a significant rain event (>0.1-feet) and the November 5 results suggested that the boom had little effect on the concentration of PFAS in storm water. On December 19-20, EGLE cleaned out two historical storm water vaults in a different location that were likely used for storm water/groundwater management during past tannery operations and re-implemented the POC with additional booms in the new location. Performance monitoring of the reconfigured boom POC study was initiated in 2020.

• PFAS Sample Collection and Analysis - In June and November EGLE collected aqueous media samples from groundwater monitoring wells; surface water and foam (when present) from the Thunder Bay River; and storm water from the historical tannery and surrounding infrastructure catch basins.
• Microbe Benchtop Assessment – EGLE collected groundwater and soil samples that were then assessed for PFAS tolerant microbes by Fixed Earth (Alberta, Canada). Fixed Earth was able to isolate microbes from the site media that were viable with PFAS as the only available carbon source. Additional benchtop testing suggested that the combination of microbes and aeration was able to achieve reductions of PFHxS, PFOS and PFOA in spiked water by 94% or more at 8-weeks. Dye testing suggested two of the six isolated microbial strains were positive for the formation of inorganic fluoride – an indication that they may be performing microbial breakdown of PFAS.
• Ongoing Performance Monitoring: Storm Water POC – EGLE’s subcontractor assessed the stormwater POC (initiated in Sept. 2019) performance in January 2020 and found that the current BAM deployment reduced total PFAS concentration in storm water by 30%, but that some storm water was able to bypass the treatment booms. On February 26 EGLE’s subcontractors deployed more BAM-filled Boom material. Additional performance monitoring was performed on the new deployments in February, April (high flow), June and November. Total PFAS were reduced by between 41% and 85% in the storm water effluent when compared to the upstream primary source.
• Ongoing Soil Treatment Pilot Test (Dec 2018) – EGLE assessed groundwater concentrations in the soil mixing and injection treatment areas in February, June and November. Some PFAS “rebound” in groundwater was found to occur, but PFAS results in November were reduced relative to baseline by over 63% in the soil mixing area and by up to as much as 93% in the injection area.

• PFAS Sample Collection and Analysis - In April and November EGLE collected samples from groundwater monitoring wells, surface water from the Thunder Bay River, and storm water from the historical tannery catch basins and other municipal catch basins. 
• Monitoring Well Installation and Abandonment - EGLE installed two new monitoring wells downgradient of the site and replaced two wells destroyed during Site-related infrastructure work. The wells were used to refine understanding of groundwater flow and were incorporated into the sitewide groundwater sampling program for PFAS. Four monitoring wells installed in the injection pilot test area and one damaged monitoring well were abandoned prior to 2021 paving activities (October 2021 – See Capping and Storm Water Mitigation).
• Microbial Pilot Test – EGLE implemented a small-scale pilot test to assess whether the PFAS-tolerant microbes cultured from Site soil and groundwater by Fixed Earth could be injected into Site groundwater with a biostimulant oxygen release compound (ORC^®) to reduce PFAS concentrations. The test was performed in the same area as the 2018 soil mixing pilot study and included an ORC-only injection test (no microbes present). Performance monitoring of the microbial treated pilot area indicated that PFOS (51%) and PFHxS (68%) decreased in the first two weeks after the application. However, PFAS rebounded as the excess dissolved oxygen produced by ORC was lost from the system. Addition of solar powered air sparging provided some dissolved oxygen and PFAS levels again decreased, but they did not reach previous lows. In the ORC-only treatment area no reduction of PFHxS or PFOS was observed.     
• Capping and Storm Water Mitigation – In October and November 2021 EGLE and its subcontractors capped (paved over) a portion of the site as an interim measure, and installed new storm water infrastructure to capture precipitation-derived storm water and more efficiently convey it to the municipal storm water system. The remedial goals of these actions were to 1) reduce seasonal flooding of PFAS-impacted groundwater to the surface, which then moved by overland flow into existing storm water infrastructure and 2) reduce the leaching of PFAS from soil into groundwater. To reduce the potential for PFAS impacted groundwater into the new storm water infrastructure the sealed piping was pressure tested (as requested by the City of Alpena) and BAM amendments were added to the trench backfill.
• Ongoing Performance Monitoring: Storm Water POC – POC performance was assessed by storm water sample collection in April and November.  Total PFAS were reduced in the treated stormwater effluent by between 55% and 53%, respectively.
• Ongoing Soil Treatment Pilot Test (Dec 2018) – EGLE assessed concentrations of PFAS in groundwater in the soil mixing area in March (prior to the initiation of the Microbial Pilot Test).  Total PFAS were reduced relative to baseline by 51%. Performance monitoring in the injection area was performed in April and November although some pilot test wells were abandoned prior to the November 2021 event and were not sampled. PFAS results in November in the injection area were reduced relative to baseline by 68 to 86%.

• PFAS Sample Collection and Analysis - In May and November EGLE collected groundwater monitoring well, surface water samples from the Thunder Bay River, and storm water samples from the historical tannery catch basins and other municipal catch basins.
• Monitoring Well Installation - EGLE installed and collected groundwater samples from ten temporary monitoring wells downgradient of the Site in June. Based on the analytical results and access granted by downgradient homeowners, two new monitoring wells were installed downgradient of the site to further delineate the extent of PFAS impacts. The new wells were incorporated into the sitewide groundwater sampling program for PFAS.
• Phyto-Enhanced Immobilization Pilot Test – The capping design included construction of a “green space” to pilot phyto-enhanced treatment of PFAS in soil and groundwater. BAM was mixed into the ground in February in three trenches that were approximately 8’ wide by 12’ deep (~base of aquifer), and over 100 feet long. TreeWells^® were planted within the trenches. TreeWells use a plastic sheath or sleeve to prevent precipitation from reaching the roots, thus forcing them to rely on groundwater. This creates an evapotranspiration pump that helps to drawdown the water table to prevent site flooding and to bring PFAS impacted water into the biochar treatment trenches. Within the sleeve of each treewell a piezometer was installed to allow depth to water to be gauged, amendments to be delivered and/or groundwater samples to be collected. A total of 36 trees (eight cedar, 18 hybrid poplars and 10 willows) and piezometers were installed. Four additional monitoring wells and nine piezometers were also installed to support hydraulic and PFAS monitoring. Groundwater samples were collected during this pilot in February (baseline), March, April (to assess/isolate BAM performance) May, August, September, October and November. High frequency sampling in August-October was performed to assess microbial bioaugmentation in some areas of the planting. Two trees were damaged in September and required replacement. Soil and tree tissue sampling was performed in October, during tree replacement. Groundwater PFAS concentrations in portions of the treated area were reduced to levels below applicable GSI Criteria (e.g., for PFOS, less than 12 PPT). When compared to trees of similar size on site, the concentration of PFAS in leaves in the treatment area were reduced by over 95% and no PFAS were detected in the fall leaf drop. The use of BAM was intended to reduce PFAS uptake into tree tissue.
• Expanded Biostimulation and Bioaugmentation Pilot Test – To further assess the potential for a microbial enhancement to degrade PFAS, EGLE applied a BAM soil mixing remedy in one of the most heavily impacted PFAS areas on the Site in August. BAM was mixed with soil from the ground surface to the base of the aquifer in an area that was 22 feet wide (directed perpendicular to groundwater flow) and 88 feet long. The area was subdivided into four squares to test two biostimulation methods to deliver oxygen to the system (oxygenation). Method one used 15 electrode “wells” to directly deliver electrical current to the system (electrolysis). Method two involved mixing ORC into the ground to enhance aerobic degradation of PFAS. In half of the two biostimulation areas, the Site-endemic microbes cultured by Fixed Earth were added (bioaugmentation). A total of 10 monitoring wells were installed to assess the pilot remedy performance. Performance monitoring included assessment of microbial diversity as well as PFAS concentrations and samples were collected weekly in August and September, bimonthly in October, and monthly in November and December form select wells. ORC mixed into the ground was found to increase pH and potentially slow potential degradation. The low conductivity of the site aquifer also hampered the effectiveness of the applied electrical current to generate oxygen. Results are under review, but the treatment area has reduced total PFAS (average 20,865 PPT) concentrations by 99% (electrolysis area) and 98% (ORC area) during the last sampling event of 2022. PFAS were not detected at levels that exceeded a GSIC only in the samples collected from the treatment block that included biostimulation (electrolysis) and bioaugmentation.
• Capping and Storm Water Mitigation – The final topcoat of the paving initiated in 2021 was applied in May 2022.
• Ongoing Performance Monitoring: Storm Water POC – POC performance was assessed by storm water sample collection in May and November. Total PFAS were reduced in the treated stormwater effluent by between 13% to 20%, respectively. Influent concentrations into the treatment area were also reduced by an additional ~25% following capping and storm water infrastructure installation.
• Ongoing Soil Treatment Pilot Test (Dec 2018) – EGLE assessed groundwater concentrations in the injection area in February, prior to the BAM soil mixing associated with the phyto-enhanced immobilization pilot test. Total PFAS remained reduced (61%) relative to baseline.

• PFAS Sample Collection and Analysis - In April and October/November EGLE collected groundwater monitoring well, surface water samples from the Thunder Bay River, and storm water samples from the historical tannery catch basins and other municipal catch basins.
• Additional Offsite Investigation - EGLE advanced soil borings and collected groundwater samples from seven temporary monitoring wells downgradient of the Site in August. PFOS was detected above GSI criteria in one location and results indicate PFAS migration directed toward Lake Huron. Based on the analytical results four monitoring wells will be installed in 2024 and incorporated into the groundwater monitoring program.
• Phyto-Enhanced Immobilization Pilot Test – Groundwater performance monitoring samples were collected during in February (when trees were dormant), July and October. Soil and tree tissue sampling was performed in October. Groundwater concentrations in portions of the treated area were reduced to levels below applicable GSIC (e.g., for PFOS, less than 12 PPT) in 5 of the 9 TreeWell^® piezometers tested. When compared to trees of similar size on Site, the concentration of PFAS in leaves in the treatment area were reduced on average by over 95%. No PFAS were detected in the fall poplar leaf drop and PFOS was only detected in one of the two samples of willow leaf drop.
• Expanded Biostimulation and Bioaugmentation Pilot Test – Performance monitoring included assessment of PFAS concentrations in groundwater performed in January, February, July and October. Electrolysis was discontinued in January. Results are under review, but total PFAS (average 20,865 PPT) concentrations have been reduced by over 95% (electrolysis area) and 96% (ORC area) as of the last sampling event completed in 2023. PFAS were again not detected at levels that exceeded a GSIC only in the samples collected from the treatment block that included biostimulation (electrolysis) and bioaugmentation.
• Ongoing Performance Monitoring: Storm Water POC – POC performance was assessed by storm water sample collection in April and November. Total PFAS were reduced in the treated effluent by 30% during the April event but increased during the November event. The effective duration of the deployed BAM-treated boom configuration is estimated to be approximately 3-4 years. Replacement is planned for 2024.
• Ongoing Soil Treatment Pilot Test (Dec 2018) – EGLE assessed groundwater concentrations in the injection area in October during annual monitoring. Total PFAS remained reduced (34%) relative to baseline.
• Bulk Fuel Pre-Design Investigation and Benchtop Testing – EGLE assessed soil and groundwater concentrations of PFAS and diesel range organics on a portion of the site that had been used historically as petroleum bulk fuel storage area and where residual non-aqueous phase liquid (NAPL) had previously been suggested. Some PFAS comingle with diesel impacts. Petroleum hydrocarbons were characterized in soil via 26 soil borings and a total of 30 PFAS soil samples were collected. Groundwater was assessed from four newly installed piezometers in the former bulk fuel area and three existing monitoring wells in August and October. A benchtop study was performed to assess BAM’s ability to reduce both diesel and PFAS in site soil. Results suggested that BAM did not meet data quality objectives for treatment via soil mixing of petroleum hydrocarbons. EGLE plans an excavation of impacted soil in 2024 with additional treatments to address PFAS.

Historical Sampling Chart: data is reflective of criteria prior to 8/1/2024: PFOS or PFOA (Only)

This chart reflects data received prior to 1/1/2024.

*Results are compared to EGLE Part 201 Criteria of 16 ppt PFOS and 8 ppt PFOA.

**Results are compared to Rule 57 surface water quality values of 12 ppt for PFOS and 170 ppt for PFOA.

Tabulated monitoring well numbers include grab groundwater samples. Pilot test performance monitoring groundwater results are not included in the above totals unless also collected as part of sitewide sampling events.