| Action Date |
Action |
Description |
DEC Staff |
| 11/21/1995 |
Site Added to Database |
|
Scott Rose |
| 12/5/1995 |
Preliminary Assessment Approved |
(Old R:Base Action Code = SA2R - Phase II SA Review (CS)). Contamination assessment report received from Alyeska. Soil contamination thought to be isolated and discrete in nature. Pad water contamination is more extensive. Exceeds water quality criteria in all 4 wells. Request additional sampling in 1996 and establishment of two surface water sampling points south of pad near MW 7 and 9. |
Scott Rose |
| 4/21/1998 |
Site Ranked Using the AHRM |
Ranking action added now because it was not added when the site was originally ranked. |
Bill Petrik |
| 1/17/2001 |
Update or Other Action |
Meltwater Sampling and Analysis Report, PS 1 Equipment Shop Area, submitted to ADEC. According to the report, IT sampled MW-4, MW-5, MW-9 and MW-10. Analytical results from meltwater samples collected from the PS1 shop-area monitoring wells indicate that benzene impact remains limited to an area near the southern edge of the pad, near MW-9. Benzene and DRO concentrations are similar to results in previous years. A surface water sample was collected adjacent to the pad near MW-9 with results of DRO 0.34 ppm and ND for benzene. IT recommends continued sampling of the monitoring well network in 2001. The presence or absence of off-pad surface water in proximity to MW-9 should be documented, and if present, sampled for TAqH in the summer of 2001. IT also recommends analyzing the surface water sample for total recoverable oil and grease by EPA method 1664 in 2001 to determine if biogenic material is the cause of the measured DRO in the surface water at this site. |
Deborah Williams |
| 8/6/2001 |
Cleanup Plan Approved |
Workplan approval for new monitoring wells and ground and surface water monitoring. |
Renee Evans |
| 3/1/2004 |
Update or Other Action |
ADEC received SLR's report on the 2003 Groundwater Monitoring and Monitoring Well Installation Report for PS 1 Equipment Shop Area. The conclusions of the report indicates that overall trends appear to be a reduction in hydrocarbon concentrations along the northern and eastern edge of the plume and slight increases within the central and western portion. In general, there appear to be two overlapping plumes, identified on the site. A central GRO plume centered around monitoring wells MW-15 through MW-19 and MW-11. A larger DRO plume overlaps the GRO plume but extends northward and eastward including monitoring wells MW-4, MW-5, MW-12 and MW-14. The source areas for these plumes has not been identified to date. The large DRO plume is centered near the Endicott and Lisburne pipeline skids. At this time, it appears that contaminated suprapermafrost groundwater is not impacting off-site surface water adjacent to the Equipment Shop area. |
Deborah Williams |
| 3/14/2005 |
Update or Other Action |
ADEC received SLR's PS 1 Equipment Shop Area 2004 Groundwater Monitoring and Soil Gas Investigation report. The soil gas investigation revealed two distinct anaomaly areas. The first area is immediately southeast of the Equipment Maintenance Building. A confirmation subsurface soil sample (B-4) collected from this area contained 172 mg/kg DRO and 968 mg/kg GRO. A second soil gas anomaly was found to be near monitoring well MW-12. The overall trend in the groundwater levels on-site appears to be a reduction in the benzene levels and an increase in GRO and DRO levels throughout the pad. The area of benzene-impacted ground water is clearly centered at well MW-11. The lateral extent of GRO- and DRO-impacted groundwater is less defined and contains multiple apparent source areas. The lateral extent of hydrocarbon-impacted groundwater is confined on the eastern portion of the pad by wells MW-20 and MW-5. Sample results along the western portion of the pad have increased significantly from historical levels. Concentrations of GRO and DRO have increased three consecutive years at wells MW-16 and MW-18.
PAH has been detected in groundwater samples but have been below ADEC cleanup levels. Surface water samples collected in 2004 contained no detectable hydrocarbons concentrations at or above the method reporting limits. |
Deborah Williams |
| 4/5/2006 |
Update or Other Action |
ADEC received the 2005 monitoring report for the PS 1 Equipment Shop Area.
In 2004, soil gas data suggested two distinct anomalies. One area was immediately southeast of the Equipment Maintenance Building and a second soil gas anomaly appeared to be centered near MW-12. Results of the 2005 soil investigation indicate that the area southeast of the Equipment Maintenance Building, between wells MW-17 and MW-19, contains soil with concentrations of GRO and DRO exceeding ADEC Method 1. Soil samples from the second anomaly, around MW-12, do not contain concentrations of hydrocarbons exceeding ADEC cleanup levels.
There are several overlapping hydrocarbon-impacted groundwater plumes identified on site. Sample results along the western-southwestern portion of the pad have increased significantly from historical levels. Since monitoring of PAHs began in 1999, no PAH concentrations have exceeded ADEC cleanup levels. The one surface water sample contained no detectable hydrocarbon concentrations at or above the method reporting limits.
SLR recommends continued monitoring of groundwater and surface water at the PS1 Equipment Shop site. They also recommend additional surface water sampling off-pad, at the southwestern corner, where GRO and DRO levels are increasing above historical concentrations. |
Deborah Williams |
| 3/14/2007 |
Update or Other Action |
ADEC received SLR's report on the 2006 Groundwater Monitoring Report and Monitoring Well installation for the PS 1 Equipment Shop site. According to the report, two new monitoring wells were installed on the southwest edge of the pad, one was installed on the southern edge of the pad and one was installed on the eastern edge of the contamination associated with the Equipment Shop area. According the sampling results, hydrocarbon concentrations in the site groundwater appear to be relatively static, except for wells MW-11, MW-14, MW-16, and MW-18. GRO concentrations in MW-11 have been decreasing since 2002. Samples collected from MW-16 and MW-18 have shown an increase in GRO and DRO since 2002. |
Deborah Williams |
| 3/16/2007 |
Exposure Tracking Model Ranking |
Initial ranking completed. |
Deborah Williams |
| 3/7/2008 |
Update or Other Action |
Receipt of Pump Station 1 Equipment Shop Area 2007 Ground Water Monitoring Report. Samples collected from 14 wells, all of which contained detectable hydrocarbon concentrations. 11 wells contained levels greater than Table C (as a guidance level). Benzene was highest in MW-11, which is historically the highest for benzene, but three times the concentration than in 2006 (and two orders of magnitude greater than Table C). DRO concentrations increased from 2006 concentrations in nine wells with a substantial increase (1.79 to 8.62 mg/L) in MW-4 which at the northern end of this site, is likely influenced by contaminants from another source area. GRO was highest in MW-15 at 5.75 mg/L and increased in four wells compared to 2006. Ground and surface water monitoring will be conducted in 2008 with the possible additon of another surface water sample location to ensure contamination is not migrating off pad. Report review including laboratory QA/QC performed 3/26/08. |
Keather McLoone |
| 3/4/2009 |
Document, Report, or Work plan Review - other |
Date of receipt of Pump Station 1 Equipment Shop 2008 Groundwater Monitoring Report. Groundwater sampling included GRO, DRO, RRO, BTEX, PAHs, and natural attenuation parameters. Results generally consistent with historical results. Surface water sampling was also conducted. Results indicate contamination not migrating offsite. Monitoring to continue in 2009. SLR recommends adding a surface water location near the southwest corner of the pad near wells that have had generally increasing DRO and GRO levels. |
Keather McLoone |
| 5/22/2009 |
Document, Report, or Work plan Review - other |
Review of Pump Station 1 Equipment Shop Area 2009 Water Monitoring Work Plan. A single groundwater and surface water sampling event is planned for 2009. SLR plans to conduct a site visit in late May or early July to determine the seasonal progression of suprapermafrost ground water thaw. |
Keather McLoone |
| 1/14/2010 |
Exposure Tracking Model Ranking |
A new updated ranking with ETM has been completed for source area 73338 petroleum release. |
Keather McLoone |
| 5/10/2010 |
Document, Report, or Work plan Review - other |
Review of Pump Station 1 Equipment Shop Area 2009 Water Monitoring Report. Thirteen groundwater and 4 surface water samples were collected in August 2009. DRO, GRO, and benzene were detected above Table C in some of the wells. MNA parameters were also assessed. None of the surface water samples collected indicated that contamination was migrating offsite. DEC has no objection to eliminating PAH analyses from future groundwater monitoring events based on 10 years of data without exceedances. |
Keather McLoone |
| 5/27/2010 |
Document, Report, or Work plan Review - other |
Review of 2010 Pump Station 1 Equipment Shop Area Water Monitoring Workplan. During a single event in 2010 the following activities are planned: groundwater sampling including MNA parameters at 13 locations, surface water sampling at 3 existing locations and possibly new surface water location near the southwest edge of the pad if water present. |
Keather McLoone |
| 3/24/2011 |
Document, Report, or Work plan Review - other |
Date of receipt of Pump Station 1 Equipment Shop Area 2010 Water Quality Monitoring Report. Twelve groundwater samples and one surface water sample were collected. Groundwater exceeded Table C for GRO, DRO, and BTEX. Third year of collection of natural attenuation parameters. Review included laboratory data review checklists. |
Keather McLoone |
| 6/1/2011 |
Document, Report, or Work plan Review - other |
Date of receipt of Pump Station 1 Equipment Shop Area 2011 Water Quality Monitoring Workplan. Alyeska proposes to conduct another groundwater and surface water sampling event. Sampling for selected monitored natural attenuation parameters is planned for the groundwater samples. |
Keather McLoone |
| 3/23/2012 |
Update or Other Action |
Date of receipt of 2011 Water Monitoring Report. Twelve of 13 wells were sampled. One well was damaged. Exceedances for GRO, DRO, and benzene were found in samples collected from ten of the eleven wells. High DRO concentrations suggest product present which might warrant being measured in the future. Four surface water samples (and a duplicate) collected showed concentrations below applicable criteria. TAH and TAqH are still not calculated correctly but would not have exceeded regardless. MNA parameters also collected at the nine wells sampled. Ferric iron, alkalinity, and nitrite were performed using field test kits. (Subsequent discussions clarified that test kits were run immediately at the well heads.) Evaluation of quality of MNA data also made difficult because calibration information, etc. for field measured parameters were not included with the report. Total iron, sulfate, sulfide and total nitrate plus nitrite were performed by the laboratory. |
Keather McLoone |
| 3/23/2012 |
Update or Other Action |
Date of receipt of 2011 Water Monitoring Report. Twelve of 13 wells were sampled. One well was damaged. Exceedances for GRO, DRO, and benzene were found in samples collected from ten of the eleven wells. High DRO concentrations suggest the presence of product, which might warrant future measurement. Four surface water samples (and a duplicate) showed concentrations below applicable criteria. TAH and TAqH are still not calculated correctly but would not have exceeded regardless. MNA parameters were collected at nine wells. Ferric iron, alkalinity, and nitrite were measured with field test kits. (Subsequent discussions clarified that test kits were run immediately at the well heads.) Evaluation of MNA data quality was complicated because field calibration information wasn't included with the report. Total iron, sulfate, sulfide, nitrite, and total nitrate were performed by the laboratory. |
Keather McLoone |
| 6/19/2012 |
Site Characterization Workplan Approved |
Approved workplan for SLR to sample groundwater and surface water, conduct maintenance/replacement/installation of three MWs, and conduct an 8-10 week long Monitored Natural Attenuation (MNA) pilot study, to include sulfate injections into wells to enrich anaerobic bioremediation potential. Bromide may accompany sulfate injection to serve as a tracer to track injectate's migration. |
Richard Bernhardt |
| 2/1/2013 |
Document, Report, or Work plan Review - other |
2012 Work Report Received. Alyeska/SLR installed 3x new monitoring wells (MW), decomissioned one damaged well, resurveyed all wells, analyzed surface and groundwater at 2 and 15 locations, respectively, and conducted a sulfate injection pilot study between 19 July ad 27 September. The sulfate injection pilot study appears to have significantly reduced DRO and benzene concentrations. Toluene was the only COC detected in surface waters, but it was well below regulatory criteria. SLR recommends continuing the sulfate injection program at the subject site and expanding its use to other sites within PS 01. The highest [GRO] was 8.65 mg/L in MW-18, and the highest [DRO] was 21.8 mg/L in MW-14. The highest [benzene] was 0.506 mg/L in MW-11, and the highest [ethylbenzene] was noted in MW-18 at 0.752 mg/L. |
Richard Bernhardt |
| 2/27/2013 |
Update or Other Action |
Updated coordinates based on comparison of 2012 work report with Google Earth imagery. |
Richard Bernhardt |
| 5/24/2013 |
Site Characterization Workplan Approved |
Received and approved a work plan to continue groundwater monitoring and sulfate injections in 2013. |
Richard Bernhardt |
| 2/26/2014 |
Site Characterization Report Approved |
On this date, ADEC received the Pump Station 1 Equipment Shop Area 2013 Water Monitoring and Pilot Study Report submitted by SLR dated February 2014. From July 30 to September 29, a total of 13 out of 15 monitoring wells and three out of four surface water locations were sampled and sulfate was injected as part of the pilot study with MNA parameters evaluated. MW-5 was not sampled because the well had been uncapped and cutoff for a period of time allowing debris to enter the well. MW-20 could not be sampled due to surface water flooding and an adjacent gravel pile. Surface water location ES-SW-1 could not be sampled due to lack of surface water. MW-15 and MW-28 were injected with sulfate as part of the pilot study since they have contained high historic concentrations of benzene and DRO. The pilot study included an initial groundwater and surface water sampling event, then three additions of sulfate solution with sampling prior to each addition, and a final sampling during the annual groundwater monitoring. The 2013 pilot sulfate injection study indicate there is not sufficient evidence to correlate the sulfate addition to a decrease in contaminants. Groundwater samples collected during the September sampling event contained petroleum constituents above table C GW cleanup levels in the following MWs: 11, 14, 15, 17, 18, 19, 21, 24, and 26. The highest GRO and DRO concentrations were detected in MW-18 with 6.54 mg/L and 15.7 mg/L respectively. The highest benzene concentration of 0.583 mg/L was detected in MW-11. Surface water samples collected during the September sampling event contained detectable levels of toluene below Alaska water quality standards. |
Grant Lidren |
| 6/10/2014 |
Site Characterization Workplan Approved |
On this date, ADEC approved the 2014 Water Monitoring Work Plan Pump Station 1 Equipment Shop Area submitted by SLR, dated May 2014. Approval was conditional upon the following amendment to the Work Plan: Groundwater samples shall be analyzed for the full list of VOCs by EPA Method 8260. |
Grant Lidren |
| 4/24/2015 |
Site Characterization Report Approved |
On this date, ADEC received the Pump Station 1 Equipment Shop Area 2014 Water Monitoring and Pilot Study Report submitted by SLR dated April 2015. From August 18 to August 27, a total of 15 monitoring wells and three out of four surface water locations were sampled and sulfate was injected as part of the pilot study with MNA parameters evaluated. Surface water location ES-SW-3 could not be sampled due to lack of surface water. The four monitoring wells MW-4, MW-18, MW-15 and MW-28 were injected with sulfate as part of the pilot study. The sulfate injection indicate there is evidence to support sulfate addition as a potential remedial technology to reduce petroleum contamination at the site. Groundwater samples collected contained petroleum constituents above table C GW cleanup levels in the following ten MWs: 4, 11, 14, 15, 17, 18, 19, 21, 24, and 26. The highest GRO and DRO concentrations were detected in MW-18 at 7.06 mg/L and MW-14 at 21.9 mg/L respectively. The highest benzene concentration of 0.331 mg/L was detected in MW-11. Surface water samples collected during the September sampling event contained detectable levels of toluene below Alaska water quality standards. |
Grant Lidren |
| 5/27/2015 |
Site Characterization Report Approved |
On this date, ADEC received the 2015 Water Monitoring and Remediation Work Plan Pump Station 1 Equipment Shop Area submitted by SLR and dated June 2015. |
Grant Lidren |
| 3/29/2016 |
Site Characterization Report Approved |
On this date, ADEC received the Pump Station 1 Equipment Shop Area, 2015 Water Monitoring and Remediation Report submitted by SLR dated March 2016. A total of 15 monitoring wells and three out of four surface water locations were sampled and sulfate was injected as part of the pilot study with MNA parameters evaluated. Surface water location ES-SW-3 could not be sampled due to lack of surface water. Monitoring well MW-15 and MW-24 were injected with sulfate as part of the pilot study. The sulfate injection indicate there is evidence to support sulfate addition as a potential remedial technology to reduce petroleum contamination at the site. However, the reduction of petroleum contamination was limited in 2015. Potential causes include: sulfate delivery issues, aerobic conditions, inconsistent redox conditions, and hydrological conditions. Groundwater samples collected contained petroleum constituents above table C GW cleanup levels in the following eight MWs: 11, 14, 15, 18, 19, 21, 24, and 26. The highest GRO concentrations were detected in MW-18 at 6.52 mg/L. The highest DRO concentrations were detected in MW-14 at 16.9 mg/L. The highest benzene concentration were detected in MW-11 at 0.448 mg/L. The groundwater gradient at the site is generally flat with flow toward the southwest. Surface water samples collected during the September sampling event contained detectable levels of toluene and xylenes below Alaska water quality standards. |
Grant Lidren |
| 6/8/2016 |
Site Characterization Workplan Approved |
The Alaska Department of Environmental Conservation (ADEC) Contaminated Sites Program (CSP) has received and reviewed the 2016 Water Monitoring and Remediation Work Plan Pump Station 1 Equipment Shop Area submitted by SLR and dated May 2016. ADEC has no objections to the Work Plan and SLR may proceed. |
Grant Lidren |
| 2/15/2017 |
Site Characterization Report Approved |
On this date, ADEC received the Pump Station 1 Equipment Shop Area, 2016 Water Monitoring and Remediation Report submitted by SLR dated February 2017. A total of 15 monitoring wells and two out of four surface water locations were sampled and sulfate was injected as part of the pilot study with MNA parameters evaluated. Surface water location ES-SW-3 and ES-SW-1 could not be sampled due to lack of surface water. Primary injection well MW-15 and secondary injection wells MW-4, MW-11, MW-17, MW-18, MW-19, and MW-24 were injected with sulfate as part of the pilot study. The sulfate injection indicate there is evidence to support sulfate addition as a potential remedial technology to reduce petroleum contamination at the site. However, only the primary injection well MW-15 had a reduction in contaminant concentrations. Groundwater samples collected contained petroleum constituents above table C GW cleanup levels in the following ten MWs: 4,11, 14, 15, 17, 18, 19, 21, 24, and 26. The highest GRO concentration was detected in MW-18 at 5.78 mg/L. The highest DRO concentration was detected in MW-14 at 24.9 mg/L. The highest benzene concentration was detected in MW-11 at 0.412 mg/L. The highest ethylbenzene and xylenes concentration were detected in MW-18 at 0.867 mg/L and 2.633 mg/L. The groundwater gradient at the site is generally flat with flow toward the southwest. Surface water samples collected during the September sampling event did not contain detectable concentrations of contaminants. |
Grant Lidren |
| 6/16/2017 |
Site Characterization Workplan Approved |
The Alaska Department of Environmental Conservation (ADEC) Contaminated Sites Program (CSP) has received and reviewed the 2017 Water Monitoring and Remediation Work Plan Pump Station 1 Equipment Shop Area submitted by SLR and dated June 2017. ADEC has no objections to the Work Plan and SLR may proceed. MW-18 will be analyzed for petroleum VOCs. |
Grant Lidren |
| 5/7/2018 |
Document, Report, or Work plan Review - other |
On this date, ADEC received the Pump Station 1 Equipment Shop Area, 2017 Water Monitoring and Remediation Report submitted by SLR dated March 2018. A total of 14 of 15 monitoring wells and two out of five surface water locations (ES-SW-5 and ES-SW-2) were sampled and sulfate was injected as part of the pilot study with MNA parameters evaluated. Monitoring well MW-11 was damaged and decommissioned. Surface water locations ES-SW-4, ES-SW-3 and ES-SW-1 could not be sampled due to lack of surface water. Primary injection well MW-15 and secondary injection wells MW-4, MW-17, MW-18, MW-19, and MW-24 were injected with sulfate as part of the pilot study. The sulfate injection indicate there is evidence to support sulfate addition as a potential remedial technology to reduce petroleum contamination at the site. Groundwater samples collected contained petroleum constituents above table C GW cleanup levels in the following seven MWs: 14, 15, 17, 18, 19, 24, and 26. Monitoring well MW-18 contained the highest: GRO concentration up to 5.53 mg/L, ethylbenzene concentration up to 0.747 mg/L, xylene concentration up to 2.42 mg/L, 1,2,4-trimethylbenzene concentration up to 0.478 mg/L, 1,3,5-trimethylbenzene concentration up to 0.163 mg/L, and naphthalene concentration up to 0.215 mg/L (note: only MW-18 was analyzed for VOCs by 8260). The highest DRO concentration was detected in MW-14 at 16.7 mg/L. The highest benzene concentration was detected in MW-15 at 0.0453 mg/L. The groundwater gradient at the site is generally flat with flow toward the southwest. Surface water samples collected during the July sampling event did not contain detectable concentrations of contaminants. |
Grant Lidren |
| 6/15/2018 |
Site Characterization Workplan Approved |
The Alaska Department of Environmental Conservation (ADEC) Contaminated Sites Program (CSP) has received and reviewed the 2018 and 2019 Water Monitoring and Remediation Work Plan Pump Station 1 Equipment Shop Area submitted by SLR and dated June 2018. ADEC has no objections to the Work Plan and SLR may proceed. All MWs will be analyzed for, GRO, DRO, petroleum VOCs, sulfate, and nitrate. This work plan is approved for 2018 and 2019. |
Grant Lidren |
| 7/31/2018 |
Site Visit |
Visited site on this date with Alyeska and SLR. |
Grant Lidren |
| 3/4/2019 |
Site Characterization Report Approved |
On this date, ADEC received the Pump Station 1 Equipment Shop Area, 2018 Water Monitoring and Remediation Report submitted by SLR dated February 2019. A total of 14 monitoring wells and two out of five surface water locations (ES-SW-5 and ES-SW-2) were sampled and MNA parameters evaluated. Surface water locations ES-SW-4, ES-SW-3 and ES-SW-1 could not be sampled due to lack of surface water. Primary injection well MW-15; secondary injection wells MW-4, MW-17, MW-18, MW-19, and MW-24; and injection performance monitoring wells MW-20, MW-21 and MW-26 were monitored for natural attenuation (MNA). Based on the MNA results, there is evidence to support sulfate addition as a potential remedial technology to reduce petroleum contamination at the site. Groundwater samples collected contained petroleum constituents above table C GW cleanup levels in the following seven MWs (same as 2017): 14, 15, 17, 18, 19, 24, and 26. Monitoring well MW-26 contained the highest: GRO concentration at 4.55 mg/L and xylene concentration at 1.79 mg/L. Monitoring well MW-18 contained the highest: ethylbenzene concentration at 0.736 mg/L, 1,2,4-trimethylbenzene concentration at 0.489 mg/L, and 1,3,5-trimethylbenzene concentration at 0.162 mg/L. MW-14 contained the highest DRO concentration up to 12.8 mg/L and naphthalene concentration up to 0.252 mg/L. The highest benzene concentration was detected in MW-15 at 0.0528 mg/L. The groundwater gradient at the site is generally flat with flow toward the southwest. Surface water samples collected during the July sampling event did not contain detectable concentrations of contaminants. |
Grant Lidren |
| 3/19/2020 |
Site Characterization Report Approved |
On this date, ADEC received the Pump Station 1 Equipment Shop Area, 2019 Water Monitoring and Remediation Report submitted by SLR dated February 2020. Six damaged monitoring wells (MW-5, MW-18, MW-20, MW-21, MW-24, and MW-26) were fixed. A total of 14 monitoring wells and two out of five surface water locations (ES-SW-5 and ES-SW-2) were sampled and MNA parameters evaluated. Surface water locations ES-SW-4, ES-SW-3 and ES-SW-1 could not be sampled due to lack of surface water. Primary injection well MW-15; secondary injection wells MW-4, MW-17, MW-18, MW-19, and MW-24; and injection performance monitoring wells MW-20, MW-21 and MW-26 were monitored for natural attenuation (MNA). Based on the MNA results, there is evidence to support sulfate addition as a potential remedial technology to reduce petroleum contamination at the site. Groundwater samples collected contained petroleum constituents above Table C groundwater cleanup levels in the following ten MWs (three more than 2018): 5, 14, 15, 17, 18, 19, 20, 21, 24, and 26. Monitoring well MW-26 contained the highest: GRO concentration at 4.89 mg/L, ethylbenzene concentration at 0.401 mg/L, and xylene concentration at 1.84 mg/L. Monitoring well MW-15 contained the highest benzene concentration at 0.046 mg/L, 1,2,4-trimethylbenzene concentration at 0.393 mg/L and naphthalene concentration at 0.457 mg/L. MW-17 contained the highest 1,3,5-trimethylbenzene concentration at 0.172 mg/L. MW-14 contained the highest DRO concentration up to 12.4 mg/L. The groundwater gradient at the site is generally flat with flow toward the southwest. Surface water samples collected did not contain detectable concentrations of contaminants. |
Grant Lidren |
| 6/11/2020 |
Site Characterization Workplan Approved |
On this date, ADEC received the water Monitoring Work Plan Pump Station 1 Equipment Shop Area submitted by SLR and dated June 2020. Groundwater and surface water will be sampled annually during the 2020 and the 2021 field season. |
Grant Lidren |
| 5/6/2021 |
Document, Report, or Work plan Review - other |
ADEC reviewed and approved the 2020 Water Monitoring and Remediation Report (received February 1, 2021), and Pump Station 1 Equipment Shop Area 2021 Remediation and Monitoring Work Plan Addendum (received May 4, 2021). Monitoring of area wells will occur before a single additional injection of sulfate and nitrate (Epsom salts, Regenesis-R, and yeast extract) or sulfate only (Epsom salts, and yeast extract). |
Laura Jacobs |
| 3/14/2022 |
Document, Report, or Work plan Review - other |
A work plan was approved for replacement of two wells at the Equipment Shop site, and six wells at the Former Gas Tank Area. DEC requested sample results for two confirmation samples that will be collected from the potential waste soil stockpile that may result from installing new wells. |
Laura Jacobs |
| 7/18/2022 |
Document, Report, or Work plan Review - other |
A multi-year (2022-2023) Water Monitoring Work Plan and an addendum were reviewed for checking monitoring well integrity, annual groundwater well sampling, surface water sampling, post-injection sample collection to monitor performance of the injected electron acceptors, nitrate and sulfate and nutrients. The work plan and addendum were approved. |
Laura Jacobs |
| 10/20/2022 |
Document, Report, or Work plan Review - other |
DEC approval of the 2021 Water Monitoring and Remediation Report was sent after meeting with APSC staff and their consultant to discuss challenges of site remediation efforts. Continued remedial efforts will occur in the future, followed with monitoring to determine whether methods and materials are effective. |
Laura Jacobs |
| 12/8/2023 |
Document, Report, or Work plan Review - other |
DEC approved the report Pump Station 1 Equipment Shop Area, 2022 Water Monitoring and Remediation Report received by staff April 11, 2023 and the Response to Comments received by staff October 18, 2023. Eleven of fourteen wells had exceedances for gasoline range organics (GRO), diesel range organics (DRO), or (PVOC) compounds. It was demonstrated that biodegradation has continued in the injection wells near the pad. No off-pad migration of petroleum hydrocarbons, nitrate or sulfate (from injections) is indicated by surface water sample results. Monitoring well MW-26 may need to be replaced in 2024 depending on results from the 2023 sample results. If replaced, MW-26 and MW-26R would be decommissioned. Continued monitoring of supra-permafrost groundwater and surface water is recommended. |
Laura Jacobs |
