| Action Date |
Action |
Description |
DEC Staff |
| 9/4/2009 |
Site Visit |
Site visit today with Anchorage PERP Staff. ML&P contractors encountered contaminated soil and groundwater along the western edge of the Operations/Warehouse building at 1201 E.1st Ave, adjacent to this site. Petroleum product began flowing into the excavation following the lowering of the water table to install utilities. A sample of the product contained PCBs at 17 mg/L, however soil samples collected from the excavation did not contain PCBs above 1 mg/kg. The UST that is the suspected source for this contamination is scheduled to be removed on 9/14/09 with additional chracterization to follow as needed. |
Bill O'Connell |
| 9/14/2009 |
Site Characterization Workplan Approved |
Reviewed Work Plan for Limited Release Investigation and Soil Removal Action During UST Removal at ML&P Operations and Dispatch Center, 1201 E. 1st Ave. This UST was discovered during dewatering operations conducted during utility installation. The UST volume is estimated at 3,000 gallons. Soil will be segregated during excavation with the objective of using the top 3 feet as backfill. Contaminated soil will be stockpiled on a liner for disposal and confirmation samples will be collected for DRO, RRO and PCBs. The UST sits within a log crib with a concrete cap, both suspected of being contaminated with PCBs as a product sample collected earlier from this tank contained PCBs up to 17 mg/l. The wood and concrete will be stored on a liner for disposal, likely as PCB-contaminated material. |
Bill O'Connell |
| 9/15/2009 |
Spill Transferred from Prevention Preparedness and Response Program |
Site transferred by PERP staff Neil Huddleston. Spill no. 09239924301; spill date = 8/31/09; substances = diesel and PCBs; quantity = unknown. |
Mitzi Read |
| 9/16/2009 |
Site Added to Database |
A new site has been added to the database |
Mitzi Read |
| 9/29/2009 |
Site Visit |
Site visit during excavation activities |
Bill O'Connell |
| 10/1/2009 |
Document, Report, or Work plan Review - other |
Reviewed workplan for groundwater sampling at 1201 East 1st Ave. Three monitoring wells currently in place at an adjacent site downgradient (1121 East 1st Ave. HAZID 23606) will be monitored for DRO, RRO, and PCBs based on observations made during the UST excavation. Additional information about this release will be included in the UST removal report, not yet received by ADEC. |
Bill O'Connell |
| 11/18/2009 |
Leaking Underground Storage Tank Cleanup Initiated - Petroleum |
UST Release Investigation Report reviewed by ADEC. The initial report was due to oily product that leaked into a utility excavation along the NW corner of the Operation/Warehouse building after a dewatering well was installed and pumping began. Water removed from the well was run through an oil/water separator, then through a settling tank with sorbent pads before being discharged to the sanitary sewer. Three stockpiles (11cy) of contaminated soil were generated during the utility excavation which were either disposed of offsite, or staged onsite for reuse. Following the utility work, a UST removal project was implemented. The 2,500-gallon tank was drained of approximately 425 gallons of fuel and 1,475 gallons of water. Visible product was present on the water table when the tank was removed, which was removed with sorbent pads. Confirmation soil samples were collected from the botom and sides of the excavation to document contaminant concentrations remaining. DRO was detected up to 17,700 mg/kg at 4 feet bgs. PCBs above cleanup level of 1 mg/kg were detected in 8 soil samples with a maximum concentration of 112 mg/kg. TCE, PCE, and 1- and 2-methylnaphthalene were also detected slightly above cleanup levels in samples collected from the smear zone below the tank. IDW was disposed of at Emerald Services, who will ultimately dispose of PCB-contaminated material at an approved landfill in the lower 48. Soil containing PCBs below 1 mg/kg and no other contaminants was stockpiled onsite for future reuse. |
Bill O'Connell |
| 11/23/2009 |
Exposure Tracking Model Ranking |
Initial ranking with ETM completed for source area id: 78816 name: Historic UST |
Bill O'Connell |
| 12/17/2009 |
Document, Report, or Work plan Review - other |
Reviewed October 2009 groundwater sampling at the Operations and Dispatch center. Samples were collected from three existing downgradient wells, B1, B2, and 2A1. PCBs and DRO were not detected, RRO was detected below the cleanup level and PCE and TCE were detected in well B2 above cleanup levels. The TCE and PCE is attributed to area-wide contamination and is not likely associated with this source area. |
Bill O'Connell |
| 1/13/2010 |
Meeting or Teleconference Held |
Meeting today with ML&P, Hoefler, and EPA to discuss PCB contamination at the former UST site at the Ops Building. ML&P intends to conduct additional investigation to delineate the extent of PCB impacts, then pursue a Risk Based Disposal Approval with EPA that will provide for ICs to control exposure to PCB contaminated soil that will be left in place. The RBDA will be issued as an addendum to the existing RBDA in place at Power Plant 1 since 2007. (3/13/15 update: no addendum was ever issued to the existing RBDA in place at power plant 1 since 2007) |
Bill O'Connell |
| 7/1/2010 |
Document, Report, or Work plan Review - other |
Reviewed Work Plan for Aditional Site Assessment at Anchorage ML&P Operations and Dispatch Center, 1201 East 1st Ave. Nine boreholes will be advanced and sampled at 0.5, 2, 4, and 6 feet bgs depending on the depth to groundwater. All samples will be analyzed for PCBs, the samples from 0.5 and 4 feet bgs will be analyzed for DRO/RRO and 25% of the 4 foot samples will also be analyzed for PAHs |
Bill O'Connell |
| 1/31/2011 |
Site Characterization Report Approved |
Reviewed 2010 Additional Site Assessment report for the ML&P Operations and Dispatch Center. The objective of the investigation was to delineate the nature and extent of hydrocarbon and PCB contamination found during utility work in 2009. Contamination became evident during excavation for utilities, after a lowering of the water table caused oily product to flow into the excavation. The source of the oily product was determined to be an inactive UST north of the building, and the source of PCBs in soil was likely a former transformer located near the inactive UST. The UST was removed from the ground in September 2009 and a total of 20 cubic yards of impacted soil from the UST and utility excavations were disposed of offsite. Characterization samples collected at the base of the UST excavation contained DRO up to 17,700 mg/kg and PCBs up to 112 mg/kg. To delineate the extent of contamination in soil, nine boreholes were advanced and sampled at various intervals in the vicinity of the former UST. DRO and RRO were not detected above the Method Two Migration to Groundwater cleanup levels. PAHs were not detected. PCBs were generally not detected or detected below the cleanup level of 1 mg/kg, except in of the samples, which contained PCBs ranging from 1.05 mg/kg to 2.5 mg/kg with one sample from borehole 9 collected at 0.5 feet bgs containing PCBs at 59.6 mg/kg. |
Bill O'Connell |
| 4/2/2015 |
Meeting or Teleconference Held |
On this date, ADEC attended a teleconference with EPA, ML&P, and SLR. EPA will require a proposal with a Site Investigation and a Risk Based Disposal Plan. The proposal will need to evaluate and/or excavate the PCBs remaining at the former transformer area located under 3 inches of asphalt along the northwest corner of the Operations Building. At this area, soil samples collected in 2009 contained PCBs up to 112 mg/kg. |
Grant Lidren |
| 10/6/2015 |
Site Characterization Workplan Approved |
On this date, EPA and ADEC received the "ML&P Operations and Dispatch Center 2015 Site Assessment and Groundwater Monitoring Work Plan" including 10/6/15 revised figures and tables. Drilling and MW installation is planned for October 12, 2015. |
Grant Lidren |
| 2/24/2016 |
Site Characterization Report Approved |
On this date, ADEC received the ML&P Operations and Dispatch Center 2015 Site Assessment and Groundwater Sampling Report submitted by SLR and dated February 18, 2016. Twelve boreholes were advanced to a depth of 12 feet bgs and sampled for PCBs with two completed as monitoring wells (MWs) and a third MW installed downgradient of the former transformer UST site. Water saturated soils were encountered at 3.5 feet bgs and the bootlegger cove was encountered at 12.5 feet bgs. Twenty five out of the 57 soil samples collected contained PCBs above the ADEC direct contact cleanup level of 1 mg/kg. Additionally, twelve of the 57 soil samples collected contained PCBs greater than the TSCA bulk remediation waste levels ranging from 55.4 mg/kg to 540 mg/kg from soil samples collected 2 to 8 feet bgs. There are estimated to be about 190 cubic yards of soil with PCBs greater than 1 mg/Kg, 110 cubic yards of soil with PCBs greater than 50 mg/Kg, and 80 cubic yards of soil with PCBs greater than 100 mg/Kg Monitoring wells 2A1, B-1, B-2, C-1, C-2, and C-3 were sampled for PCBs and VOCs. PCBs were not detected in the MWs. All of the monitoring wells contained detectable concentrations of contaminants including benzene, 1,1-DCA, cis-1,2-dichloroethene, PCE, and TCE. Five of the 6 MWs contained PCE and TCE above groundwater cleanup levels with PCE up to 0.0224 mg/L and TCE up to 0.0123 mg/L. Groundwater encountered at 2.71 to 5.38 feet bgs was flowing to the west. |
Grant Lidren |
| 12/17/2020 |
Document, Report, or Work plan Review - other |
Risk-based disposal plan submitted by Chugach Electric Association. |
Janice Wiegers |
| 1/28/2021 |
Meeting or Teleconference Held |
DEC staff met with EPA to discuss the ODC RBDP and concerns at the site to gain an idea of how the contamination would be managed with combined regulations. Groundwater monitoring will be conducted with DEC regulations in mind. Capping of the site will be discussed with Chugach Electric by EPA to ensure TSCA regulations will be followed. A covenant under UECA will be recommended by DEC to cover the facility instead of the deed restriction typically used under TSCA. |
Tim Sharp |
| 2/25/2021 |
Document, Report, or Work plan Review - other |
DEC sent comments for the Draft RBDP. DEC recommends a UECA as a substitution for a deed restriction, as it may be used facility wide for ease of closure with ICs in the future. DEC also requested scheduling for future sampling events, and an estimate of extent and volume of PCB contaminated soil above 10 ppm. Chugach Electric will re-submit to EPA and ADEC after amending. |
Tim Sharp |
| 5/27/2021 |
Document, Report, or Work plan Review - other |
Approved Final RBDP. Sampling will be biannual starting in July 2021. Wells C-1 C-2 and C-3 will be sampled for DRO and RRO for the first event. If DRO or RRO are detected above CULs, they will be added to the biannual sampling. If they are not detected, sampling for these COCs will be dropped. Chugach Elec is aware of the UECA recommendation but is not pursuing at this time as they do not foresee closure in the near future. |
Tim Sharp |
| 12/16/2021 |
Document, Report, or Work plan Review - other |
DEC sent comments on the 2021 Draft Groundwater Monitoring Report for the Chugach Electric ODC site. 6 wells were sampled for water depth and flow direction. C-1, C-2, and C-3 were sampled for DRO and RRO, as well as PCBs, as described in the SAP. No PCBs were detected, and DRO and RRO were detected below Table C. As explained in the SAP, this demonstrates absence of DRO and RRO in this area of the site and thus sampling for DRO and RRO will be discontinued for future sampling events. The wells will continue to be sampled for PCBs biannually (every other year) until PCB contaminated soils can be removed to below DEC cleanup levels in the soil. |
Tim Sharp |
| 12/23/2021 |
Document, Report, or Work plan Review - other |
DEC Approved the Final 2021 Groundwater Monitoring Report. Changes were minimal from the draft document |
Tim Sharp |
| 3/15/2024 |
Document, Report, or Work plan Review - other |
DEC approved the final 2023 Groundwater Monitoring Report. The report recommends continued biannual groundwater monitoring of PCB and the replacement or location of MW C-2. |
Livia Bracker |
