| Action Date |
Action |
Description |
DEC Staff |
| 5/4/1973 |
Preliminary Assessment Approved |
(Old R:Base Action Code = SI - Site Investigation). Report on monitoring of 4/14/73 JP-4 spill of 4262 gallons. Indicate spill contained in radius of 68 to 81 feet. |
Former Staff |
| 5/27/1988 |
Update or Other Action |
(Old R:Base Action Code = SI - Site Investigation). ARCO submitted borehole program to evaluate entire COTU pad. |
Former Staff |
| 6/7/1988 |
Update or Other Action |
(Old R:Base Action Code = FI - Field Inspection (General)). Site visit by R. Cormack to inspect proposed borehole locations. |
Rich Cormack |
| 7/27/1988 |
Update or Other Action |
(Old R:Base Action Code = SI - Site Investigation). EPA investigated allegations by 3 former ARCO employees regarding lack of oil spill reporting and cleanup, water and gravel pad contamination, and improper disposal of chemicals and hazardous wastes. Substantiated several allegations regarding failure to report spills and perform cleanup. |
Former Staff |
| 7/1/1989 |
Update or Other Action |
(Old R:Base Action Code = F - Site Treatment, Soil/H2O). Four recovery wells installed at COTU sometime in July 1989. As of 2/21/90, 20,350 gallons of water were removed, of which 65 gallons were product. |
Former Staff |
| 2/23/1998 |
Site Added to Database |
QA\QC revealed that this action was not previously added. |
Bill Petrik |
| 6/18/2004 |
Site Characterization Report Approved |
DEC received 2003 RI & Monitoring report on 5/20/04. Hydrocarbon impact identified at 2 of 6 surface water locations. Surface water monitoring to be performed in August 2004. Boreholes installed & DRO exceeded CU level in one sample. |
Linda Nuechterlein |
| 6/22/2004 |
Update or Other Action |
During site inspection on this day, hydrocarbon sheen was observed along the southern edge of the pad. BP intends to conduct additional site characterization and corrective action during summer 2004. |
Linda Nuechterlein |
| 10/25/2004 |
Update or Other Action |
The objective of the work effort in 2004 will be further characterization of site conditions through installation of new wells, and continued monitoring of existing wells to document concentration trends. Surface water will be characterized at previously established sites as well as at two additional locations. The additional assessment activities in this workplan are intended to take place before the monitoring activities to enable monitoring of the newly installed wells at the same time as the existing wells. |
Linda Nuechterlein |
| 6/21/2006 |
Update or Other Action |
Received 2005 Annual Monitoring Report. Primary source identified as petroleum impacted soil near the dispenser islands, however source area mitigation described as challenging due to continued fueling operations, high traffic, and buried fuel lines/utilities. Hydrocarbon plume in pore water described as stable over the last 8 years. Free phase product likely in pore water at source area.
Sampling conducted in 2005 included 7 of the 34 monitoring wells, and the 8 established surface water sampling locations. Active layer water flow shown to be in a westerly direction. Each of the seven wells sampled contained DRO and/or GRO and/or benzene at concentrations above Table C cleanup levels. Maximum benzene concentration of 2.28 mg/l found in well MW3-97. Maximum concentrations of DRO, 4.05 mg/l, and GRO, 7.60 mg/l also found in this well, which is located across Spine Road from the suspected source area. Surface water samples found benzene at 0.0573 mg/l at monitoring point SW8. |
Bill O'Connell |
| 3/21/2007 |
Exposure Tracking Model Ranking |
|
Bill O'Connell |
| 5/2/2007 |
Update or Other Action |
Received COTU South 2006 Monitoring Report and conducted QA/QC review. 7 of the 34 monitoring wells were sampled in 2006, typically along the leading edge of the plume. DRO/GRO/BTEX detected at concentrations exceeding cleanup levels in each of the 7 wells sampled with maximum concentrations of benzene at 2.29 mg/l, DRO of 3.24 mg/l and GRO of 11.3 mg/l, all in MW3-97. Statistical analysis of trends in wells with more than 5 years of data indicate a generally stable plume resulting from a historic release. |
Bill O'Connell |
| 7/19/2007 |
Site Characterization Workplan Approved |
Received 2007 water quality monitoring work plan for COTU North and COTU South.
At COTU North, up to nine soil borings will be advanced and completed as monitoring wells to replace wells that were lost or damaged. Two well points will be installed by hand north of the site near the treatment pond, and two surface water locations will be sampled.
At COTU South, 9 monitoring wells and 8 surface water locations will be sampled. |
Bill O'Connell |
| 1/30/2008 |
Update or Other Action |
Work Plan received for secondary containment liner upgrades at COTU and MCC. Soil samples will be collected at each location during upgrade. |
Bill O'Connell |
| 7/1/2008 |
Site Characterization Report Approved |
2007 Monitoring report received for COTU South. Active layer water samples were collected from 9 of 34 monitoring wells and 8 surface water samples were collected from established monitoring locations. A statistical analysis of active layer sample data from 5 wells indicates an upward trend in contaminant concentrations at MW3-97, but no decisive trends in the other 4 wells. Results from this monitoring effort indicated DRO, GRO, or benzene above Table C cleanup levels or AWQS in 8 of the 9 wells sampled with DRO up to 6.17 mg/l, GRO up to 13.8 mg/l and benzene up to 2.69 mg/l. Surface water samples contained BTEX at very low concentrations in three samples, but none exceeded AWQS. |
Bill O'Connell |
| 5/18/2009 |
Document, Report, or Work plan Review - other |
Reviewed 2008 Monitoring Report for COTU South. 20 active-layer monitoring wells were sampled for DRO, GRO, and BTEX and 8 surface water samples were analyzed for BTEX with a subset of those samples also analyzed for DRO and PAHs. DRO, GRO and BTEX were detected above Table C groundwater cleanup levels with DRO detected up to 6.91 mg/l, GRO up to 187 mg/l and benzene up to 32.5 mg/l. Results indicate a generally stable plume. Surface water samples contained detectable concentrations of benzene and naphthalene, however DRO was not detected and all detections are below AWQS. Benzene was detected at surface water sampling locations SW1 and SW7 for the first time. |
Bill O'Connell |
| 7/15/2009 |
Document, Report, or Work plan Review - other |
Reviewed COTU South 2009 Monitoring, Characterization, and Pilot-Scale Test Work Plan. Activities planned for 2009 include active layer water quality monitoring, surface water sampling, surveying and water level gauging, visual inspection of surface water for sheen, installation of pressure transducers, collection of thermistor data, trenching and sulfate injection pilot study, and monitoring well installation to monitor the effectiveness of sulfate injection. As the plume at COTU south has been determined to be anaerobic in nature, the sulfate injection pilot study is intended to evaluate the effectiveness of sulfate injection at increasing the rate of anaerobic degradation of hydrocarbons via sulfate reduction. A 20-foot long trench will be excavated to tundra grade and two slotted PVC pipes will be bedded in gravel in the trench and monitoring wells will be installed on either side of the injection trench. |
Bill O'Connell |
| 9/23/2009 |
Document, Report, or Work plan Review - other |
Reviewed work plan for soil sampling along the southern toe of the COTU Pad. The objective of sample collection is to assess whether petroleum sheen on surface water is caused by hydrocarbons migrating from the pad into the sediment of if another mechanism is responsible for recent observations of sheen along the toe of the pad. Along each of five transects perpendicular to the pad edge, two or possibly three soil borings will be advanced by hand auger to the frozen layer, approximately 18-24 inches deep, and samples will be collected at three intervals in each borehole and analyzed for DRO, RRO, GRO, and BTEX. |
Bill O'Connell |
| 6/25/2010 |
Document, Report, or Work plan Review - other |
Reviewed 2009 Monitoring and Pilot-Scale Injection Test Report for COTU South. 24 monitoring wells were sampled in 2009. Eight wells and six new wells were sampled bi-weekly to monitor the sulfate injection pilot test. Eight surface water samples were collected from established surface water monitoring locations, and shovel sheen testing was conducted at 17 observation stations. Four soil samples were collected during installation of the new monitoring wells and four soil samples were collected along the toe of the pad. Surface water samples did not contain TAH or TAqH above water quality criteria. Sheen was noted at 6 observation stations on various occasions and provided the basis for soil sampling along the edge of the pad. Soil samples collected along the edge of the pad contained DRO up to 346 mg/kg. Soil samples collected from boreholes during monitoring well installation on either side of the sulfate injection trench contained DRO up to 604 mg/kg and GRO up to 455 mg/kg in the 4-5 foot interval of borehole SB1-09. Pore water samples collected from monitoring wells contained benzene above groundwater cleanup levels in all wells except MW2-97 and MW2-98, located along the eastern edge of the plume, with a maximum benzene concentration detected in MW8-04 at 53.6 mg/l. The sulfate injection pilot test consisted of a 30-foot long trench, one foot wide excavated to 5 feet bgs. A 16-foot long section of 2-inch slotted PVC pipe was placed 4 feet bgs and bedded in gravel. Monitoring wells were installed on either side of trench to evaluate the impact of the sulfate injection in the immediate area of the pilot test. Samples collected throughout the duration of the pilot test found hydrocarbon concentrations decreased immediately after the initial injection in July, likely due to dilution, however concentrations had increased to levels similar to those found before the treatment injection by the end of September. Additional evaluation of the active layer hydrology is being conducted by Dr. David Barnes from UAF, whose results will be presented in another report. |
Bill O'Connell |
| 7/22/2010 |
Document, Report, or Work plan Review - other |
Reviewed 2010 Monitoring, Characterization, and Pilot Scale Test Work Plan for COTU South. Activities planned for 2010 include annual water quality monitoring of surface and pore water, water level measurements, sheen testing along the southern and western toe of the COTU pad, well surveying, installation of pressure transducers, sulfate injection into the existing injection trench, monitoring well installation, and installation of a new trench filled with gypsum aggregate as a sulfate source in an area north of the existing trench between the bulk fuel tanks and the road. |
Bill O'Connell |
| 5/17/2011 |
Document, Report, or Work plan Review - other |
Reviewed Work Pan for COTU South 2011 Corrective Measures. Activities planned for this season include installing 4 new monitoring wells to evaluate the hydrologic cycle along the southern edge of the pad, evaluating natural attenuation along the southern edge of the pad and a continuation of the sulfate injection pilot study. |
Bill O'Connell |
| 6/23/2011 |
Document, Report, or Work plan Review - other |
Reviewed 2010 Monitoring and Pilot Scale Test Report for COTU South. Activities conducted in 2010 included routine pore water and surface water sampling, multiple rounds of depth-to-water measurements, weekly shovel sheen testing along the southern and western toe of the pad, installation of dataloggers and pressure transducers, installation of a treatment trench filled with gypsum and gravel, monitoring well installation/ soil sampling and sulfate injection testing. 24 pore water monitoring wells were sampled in 2010 with 14 of those wells samples bi-weekly to gauge the effectiveness of the sulfate injection and gypsum treatment pilot studies. Pore water samples contained DRO up to 5.85 mg/l, GRO up to 261 mg/l, and benzene up to 53 mg/l. Wells with the greatest contaminant concentrations were generally located north of Spine Road near the source area and contaminant concentrations were generally consistent with previous results. Surface water samples were collected from 8 established monitoring locations. Benzene was detected in two of the samples, but none of the samples had TAH or TAqH above Alaska Water Quality Standards. Shovel sheen testing observed slight to moderately heavy sheen at 14 of the 18 observation stations consistent with previous observation and served as the basis for sediment sample collection along the southern toe of the pad. Sediment samples were collected near observation stations OS-5 and OS-10 and contained DRO up to 715 mg/kg near OS-10. Subsurface soil samples were collected during the installation of new monitoring wells associated with the sulfate and solid phase (gypsum) treatment trenches. Near the sulfate trench, located mid-plume south of Spine Road, DRO was detected up to 2,040 mg/kg, GRO up to 873 mg/kg and benzene up to 18.1 mg/kg. Near the solid phase trench north of Spine Road closer to the source area, DRO was detected up to 252 mg/kg, GRO up to 2,090 mg/kg and benzene up to 41.5 mg/kg. Pore water samples were collected from monitoring wells on either side of the sulfate injection trench on a bi-weekly basis to evaluate the impact of sulfate injection on groundwater contaminant concentrations. Sampling indicted contaminant concentrations remained stable throughout the monitoring period and did not show a decrease during the monitoring period. Pore water samples were also collected from monitoring wells on either side of the solid phase treatment trench on a bi-weekly basis to evaluate the impact of the solid phase treatment on groundwater contaminant concentrations. Contaminant concentrations increased in all wells during the monitoring period. Investigation conducted in 2010 indicates the contaminant along the edge of the pad is primarily DRO whereas the main plume at the site is GRO. Further investigation is recommended to evaluate plume stability. Evaluation of datalogger and transducer data will be conducted by Dr. David Barnes and submitted under separate cover. |
Bill O'Connell |
| 7/20/2011 |
Document, Report, or Work plan Review - other |
Reviewed 2011 work plan for COTU South. Porewater samples will be collected from 10 wells and analyzed for DRO, GRO, and BTEX. Additional porewater and surface water monitoring will be conducted as part of a Corrective Measures study submitted in May 2011 under separate cover. |
Bill O'Connell |
| 5/1/2012 |
Document, Report, or Work plan Review - other |
Reviewed COTU South 2011 Monitoring and Corrective Measures Study Report. Pore water monitoring was conducted at 32 wells in 2011 including the 8 newly installed wells along the southern edge of the pad, existing wells, and wells intended to monitor the effectiveness of the sulfate injection pilot study. Surface water samples were collected from 8 established monitoring locations, sheen testing was conducted at 18 observation stations, and two sediment samples were collected from locations exhibiting moderate to heavy sheen. Soil samples were collected from 6-10 feet bgs during installation of the new wells (plus 2 soil borings) to evaluate the presence of contamination at deeper intervals in the subsurface. At the sulfate injection pilot study area, 8 monitoring wells were sampled followed by the injection of the sulfate solution into the injection trench. At the solid phase sulfate pilot study area, water quality parameters were evaluated downgradient of the trench. Pressure transducers were installed into 14 monitoring wells in coordination with Dr. Barnes from UAF and a vegetation inspection was conducted south of the COTU pad.
Soil samples collected from boreholes detected DRO up to 1,980 mg/kg and hydrocarbon impacts were suspected in 4 of the boreholes. However hydrocarbon impacts were generally limited to the upper few feet of soil, indicating a lack of deeper impacts. The highest concentrations were along the southern pad edge at boreholes MW1-11 and MW2b-11.
The groundwater monitoring efforts in 2011 were grouped into three sections 1. Annual water quality monitoring 2. Edge of pad monitoring for natural attenuation of hydrocarbons and 3. Sulfate amendment pilot study monitoring. The annual pore water quality monitoring was generally consistent with previous results; contaminant concentrations are higher closer to the COTU source area then gradually attenuate as contamination migrates southwest across spine road towards the edge of the pad. GRO was detected up to 204 mg/l in well MW8-04 and benzene was detected up to 46.3 mg/l in the same well. Edges of pad pore water monitoring is conducted to evaluate potential migration to the tundra. Contaminants in pore water are largely attenuated by the time they reach the edge of the pad. GRO was detected up to 3.83 mg/k at MW5-02, DRO was detected up to 3.58 mg/l at MW1-11, and benzene was detected up to 0.684 mg/l at MW4-11. As noted above, surface water samples located adjacent this pad edge did not contain contaminants above AWQS. At the sulfate injection trench, pore water samples were collected before the injection of sulfate, three weeks following injection, and again eight weeks following injection. Sample analysis did not indicate a decrease in contaminant concentrations. At the solid-phase sulfate trench, pore water samples were collected on three occasions. Downgradient samples indicated fluctuating concentrations of benzene and GRO suggesting temporal variations, but not a decrease in contaminant concentrations attributable to the sulfate treatment.
Surface water quality monitoring along the southern and western pad edges did not detect contaminants above AWQS. Sheen testing found moderate to heavy sheen at observation station (OS) 5, OS-10 and OS-11, and light to moderate sheen was noted at 7 other OSs. The vegetation study found mostly grasses, and there was no evidence that hydrocarbon contamination has impacted the vegetation in the area.
|
Bill O'Connell |
| 6/4/2012 |
Document, Report, or Work plan Review - other |
Reviewed 2012 Corrective Measures Study Work Plan for COTU South. 2012 work is divided into two primary tasks; the hydrologic cycle study and the edge of pad natural attenuation study. Proposed activities for the hydrologic cycle study include the advancement of soil borings, installation, development and sampling of 3 monitoring wells, 5 thermistors, and up to 33 pressure transducers. The objective of the hydrologic cycle study is to provide data on the migration of contaminants through the gravel pad. Proposed activities for the edge of pad natural attenuation study include installation, development and sampling of 7 hand driven well points along the southern edge of the pad, sheen observations, surface water and pore water elevation gauging, collection of water quality parameters and additional surface water and pore water sampling. Previous data indicates that very little contamination is migrating from the on pad plume into the surrounding tundra, so the objective of the edge of pad natural attenuation study is to evaluate the impact of natural attenuation on the plume in this area. |
Bill O'Connell |
| 7/31/2012 |
Document, Report, or Work plan Review - other |
Reviewed work plan for water quality monitoring at COTU South. Pore water samples will be collected from 39 wells. Surface water sampling will be conducted in accordance with the Corrective Measures Study work plan |
Bill O'Connell |
| 5/10/2013 |
Update or Other Action |
Discrete areas of hydrocarbon contamination were noted in soil in the immediate vicinity of this site during installation of a gas line in 2012. |
Bill O'Connell |
| 6/19/2013 |
Document, Report, or Work plan Review - other |
Date of receipt of Corrective Measures Study and Contaminated Sites Monitoring Report reviewed 10/2/13. Activities in 2012 included monitoring of pore water and surface water, visual inspections for sheen, datalogging of water levels and thermistors, and continuation of pilot-scale solid-phase sulfate test. Also conducted as part of these activities was installation of 3 new monitoring wells, 5 thermistor string installations, 7 well point installations, and analysis of pore water for heterotrophic bacteria and MNA parameters. Conclusions were that the pore water plume is stable (especially compared to previous years), off-pad impacts are absent or negligible, sheen along pad edge located similarly to past years but no sediment samples collected in 2012, the heterotrophic bacteria counts show a narrow zone near and parallel to the pad edge where the counts are highest, and increase sulfate concentrations downgradient of the solid-phase trench coincide with decrease benzene concentrations. |
Keather McLoone |
| 8/8/2013 |
Document, Report, or Work plan Review - other |
Reviewed COTU South water quality monitoring work plan. Pore water samples will be collected from 22 wells, surface water samples will be collected from 10 established monitoring locations and field observations will be recorded. |
Bill O'Connell |
| 3/28/2014 |
Document, Report, or Work plan Review - other |
Date of receipt of 2013 RCRA Annual Report. Appendix A addresses work conducted at SWMU Project Groups to Fulfill Other Obligations and includes documenting the type of work performed during the summer of 2013 at this site. Results are to be reported elsewhere. The hydrologic study, solid phase trench monitoring, and annual monitoring were conducted. Twenty-two monitoring wells and ten surface water locations were sampled for DRO, GRO, and BTEX. Surface water was also sampled for PAHs. |
Keather McLoone |
| 8/1/2014 |
Document, Report, or Work plan Review - other |
Date of receipt of hardcopy document (received also via email on 7/25) entitled Crude Oil Topping Unit - South, 2014 Corrective Measures Study and Contaminated Site Monitoring Work Plan. The Corrective Measures Study includes advancing and sampling four boreholes, These samples will be submitted for GRO/DRO/RRO, BTEX, and PAH. Monitoring wells will be installed in each borehole. Two of these wells are to replace MW5-03 which was destroyed by a grader in 2013 and two will be placed for DO monitoring along the south edge of the pad. DO data loggers will be installed in each of the four new wells. Also included in this study will be MNA parameters and hydraulic conductivity measurements of tundra pond soil and pad gravel. The Monitoring effort will include pad porewater and surface water sampling. Thirty two monitoring wells and well points will be sampled. Part of this effort is sampling of four wells in support of the solid-phase sulfate amendment pilot-scale test trench study. Ten surface water locations will be sampled. Water quality analytical suite is GRO/DRO and BTEX (as well as some wells for MNA) with PAH added for surface water. |
Keather McLoone |
| 8/12/2014 |
Document, Report, or Work plan Review - other |
Date of receipt of 2013 Corrective Measures Study Comprehensive Report DRAFT. Activities performed included borehole advancement, monitoring well installation, subsurface soil sampling, thermistor string installation, pressure transducer installation both on and off pad, permafrost probing, permeameter and slug testing, pad porewater sampling, and surface water sampling. Deviations from the workplan were minor. Overall conclusions were plume stability based on Mann Kendall, off-pad impacts are absent or negligible, pad porewater flow direction reversal at pad edge, and solid-phase sulfate application in 2010 may be contributing to reduction in contaminant concentrations. The hydrology study will be reported under separate cover. Recommendations section states that 2014 hydrology study may not be warranted. Water quality at select locations to further document temporal trends and absence of impact to surface water beyond pad. Also recommend that at least two wells be installed to replace the damaged MW5-03. Also, initiate automated DO testing in effort to document water flow reversals with data loggers in up to six wells. Also, MNA in at least 15 wells and continued monitoring of the effects of the sulfate pilot-scale test. |
Keather McLoone |
| 8/26/2014 |
Document, Report, or Work plan Review - other |
Date of receipt via email of Materials Management and Excavation Plan, Crude Oil Topping Unit (COTU) Tanker Truck Loading Area. Conditionally approved on the following basis: If suspected or confirmed contamination is encountered and samples are not to be collected, CS should be notified as to why they won't be and concurrence sought. CS should also be part of the notification loop is contamination (known or suspected) is encountered and samples will be collected. |
Keather McLoone |
| 9/2/2014 |
Document, Report, or Work plan Review - other |
Date of letter sent with conditional approval of Materials Management and Excavation Plan, Crude Oil Topping Unit (COTU) Tanker Truck Loading Area. This plan is for the COTU South site but in an area not yet known to be contaminated. |
Keather McLoone |
| 9/4/2014 |
Site Visit |
|
Keather McLoone |
| 11/17/2014 |
Update or Other Action |
Date of receipt of letter dated 11/12/2014 summarizing management of contaminated soil for the proposed excavation. This letter also describes activities and results after BP decided to collect soil samples prior to excavating. Samples were analyzed for GRO, BTEX, and TCLP-BTEX with concentrations of GRO up to 10,300 mg/kg, benzene up to 17.4 mg/kg, and total BTEX above 15 mg/kg. The approach proposed will no longer include water washing but rather hydro-vac (air wand) and hand digging to expose fuel line that will be inspected. TCLP results and a figure were forwarded via email on 12/3/2014 as requested. ADEC emailed that we had no particular objection to the revised approach. |
Keather McLoone |
| 12/15/2014 |
Update or Other Action |
DEC notified on this date that the effort associated with the revised Materials Management Plan is postponed. |
Keather McLoone |
| 6/12/2015 |
Document, Report, or Work plan Review - other |
Date of document entitled 2014 Crude Oil Topping Unit Tanker Truck Loading Area Pre-Excavation Assessment Summary Report. Activities performed included advancing six boreholes and collecting samples analyzed for GRO, BTEX and TCLP benzene. Results indicate that while soil that is planned for excavation will exceed Method One and Method Two cleanup levels, it should not exceed RCRA. Results from this report are intended to finalize the MMEP for excavation planned at COTU TTLA. |
Keather McLoone |
| 7/29/2015 |
Document, Report, or Work plan Review - other |
Date on Transmittal of the 2015 Contaminated Sites Water Quality Monitoring Workplan for D Pad, Service City, COTU North, COTU South, BOC Bulk Fuel Facility Utilidor, DSM Shop, PBOC Generator, MCC Fuel Island. As of 10/15/15 an approval letter hadn't been sent because ERM/BP had not yet provided the 2014 COTU South report although it has been reportedly just about ready for 2 months. |
Keather McLoone |
| 12/10/2015 |
Document, Report, or Work plan Review - other |
Date of receipt of 2014 Corrective Measures Study Comprehensive Report, COTU South Site. This report also includes information on monitoring of pad porewater and surface water monitoring. In this document, the Corrective Measures Study is comprised of the hydrologic cycle study and the solid-phase trench monitoring. The solid-phase trench effort is in addition to a past effort to inject sulfate-amended water starting in 2010 and discontinued in 2012 after it was observed that although sulfate concentrations increased in pad porewater there was not a corresponding decrease in benzene concentrations.
Field activities included advancing boreholes, installing wells, soil sampling, gauging porewater and surface water level, permeameter and slug in order to better understand the hydraulic conductivity, porewater sampling for GRO/BTEX/DRO and MNA parameters, surface water sampling for GRO/DRO/BTEX/PAHs, installing DO loggers, surverying and management of IDW. Deviations from the workplan were limited and did not seem to present a particular concern.
An increasing trend in benzene was noted in wells MW3-12, MW2-11 and MW4-11 which was acknowledged as warranting attention in 2015 although it is also stated. MW3-14 and MW4-14 were installed in 2014 as replacements for well MW5-03 which had been damaged. MW5-03 and its 2 replacement wells are also indicative of an increasing benzene trend. The majority of the plume as a whole appears to be stable.
There are no significant offsite impacts at this times as TAH/TAqH at 10 surface water locations are below the standards. Pad porewater flow reversals occur at the pad edge but this is dependent on several factors including depth of pad thaw, surface water levels, precipitation and more.
Pressure transducers were not installed during 2014: therefore, 2013 was the most recent year for a complete water elevation data set.
ADEC requested that Mann-Kendall trend analysis of DRO for all well locations at the site be included in the 2015 report and that the locations that show increasing benzene trends be included in future monitoring events that might focus on select wells.
|
Keather McLoone |
| 12/10/2015 |
Document, Report, or Work plan Review - other |
Date of receipt of 2014 Corrective Measures Study Comprehensive Report, COTU South Site. This report also includes information on monitoring of pad porewater and surface water monitoring. In this document, the Corrective Measures Study is comprised of the hydrologic cycle study and the solid-phase trench monitoring. The solid-phase trench effort is in addition to a past effort to inject sulfate-amended water starting in 2010 and discontinued in 2012 after it was observed that although sulfate concentrations increased in pad porewater there was not a corresponding decrease in benzene concentrations.
Field activities included advancing boreholes, installing wells, soil sampling, gauging porewater and surface water level, permeameter and slug in order to better understand the hydraulic conductivity, porewater sampling for GRO/BTEX/DRO and MNA parameters, surface water sampling for GRO/DRO/BTEX/PAHs, installing DO loggers, surverying and management of IDW. Deviations from the workplan were limited and did not seem to present a particular concern.
An increasing trend in benzene was noted in wells MW3-12, MW2-11 and MW4-11 which was acknowledged as warranting attention in 2015 although it is also stated. MW3-14 and MW4-14 were installed in 2014 as replacements for well MW5-03 which had been damaged. MW5-03 and its 2 replacement wells are also indicative of an increasing benzene trend. The majority of the plume as a whole appears to be stable.
There are no significant offsite impacts at this times as TAH/TAqH at 10 surface water locations are below the standards. Pad porewater flow reversals occur at the pad edge but this is dependent on several factors including depth of pad thaw, surface water levels, precipitation and more.
Pressure transducers were not installed during 2014: therefore, 2013 was the most recent year for a complete water elevation data set.
ADEC requested that Mann-Kendall trend analysis of DRO for all well locations at the site be included in the 2015 report and that the locations that show increasing benzene trends be included in future monitoring events that might focus on select wells.
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Keather McLoone |
| 8/9/2016 |
Document, Report, or Work plan Review - other |
Reviewed the 2016 Contaminated Sites Soil & Water Quality Monitoring Work Plan, dated August 2016. Proposed activities mainly consist of monitoring well sampling, surface water sampling, and surface soil sampling. |
Joshua Barsis |
| 6/7/2017 |
Document, Report, or Work plan Review - other |
Reviewed the Crude Oil Topping Unit – South 2016 Contaminated Sites Monitoring Report and 2017 Work Plan, dated May 2017. This document includes a description of the 2016 field effort completed, along with a work plan for 2017 activities.
Field activities were completed between August 11 and 14, 2016 and generally consisted of surface water and pad porewater monitoring. Analytical samples were collected and submitted for laboratory analysis from 28 of 30 planned monitoring wells and well points (13 of which are considered closely connected with surface water), and from 12 surface water locations. A sample was not collected from MW12-96 because of the presence of product. A sample was not collected from MW4-03 because it was inaccessible.
All samples were submitted for laboratory analysis of gasoline range organics (GRO), diesel range organics (DRO), and benzene, toluene, ethylbenzene, and xylenes (BTEX). In addition, the samples collected from surface water were also analyzed for polycyclic aromatic hydrocarbons (PAHs). Groundwater flow direction and gradient was reported to the southwest at a gradient between 0.002 and 0.005 feet per foot. It should be noted that the flow direction is subject to reversal.
None of the samples collected from surface water exceed the Alaska Water Quality Standards (AWQS) for total aromatic hydrocarbons (TAH) or total aqueous hydrocarbons (TAqH). Results from the monitoring wells and well points varied, however most of the samples had contaminant results in excess of their applicable standard; either AWQS or Table C.
Activities proposed for the 2017 field season generally consist of continuing surface water and pad porewater monitoring.
ADEC requested a revised report by July 15, 2017 to address agency comments. |
Joshua Barsis |
| 7/18/2017 |
Document, Report, or Work plan Review - other |
Reviewed the revised document titled Crude Oil Topping Unit – South 2016 Contaminated Sites Monitoring Report and 2017 Work Plan, dated July 2017. This document is a revised version of the May report submittal. Not all ADEC comments were addressed because of time constraints, however, they will be addressed in the 2017 report (likely to be received in March 2018). |
Joshua Barsis |
| 7/17/2018 |
Document, Report, or Work plan Review - other |
Reviewed the Crude Oil Topping Unit – South 2017 Contaminated Sites Monitoring Report and 2018 Work Plan, dated June 2018. This document includes a description of the 2017 field effort completed, along with a work plan for 2018 activities.
Field activities were completed in August 2018 and generally consisted of surface water and pad porewater monitoring. Analytical samples were collected and submitted for laboratory analysis from 30 monitoring wells and well points (14 of which are considered closely connected with surface water) and from 12 surface water locations. Groundwater flow direction was reported to the west-southwest at a gradient between 0.002 and 0.005 feet per foot.
None of the samples collected from surface water exceed the Alaska Water Quality Standards (AWQS) for total aromatic hydrocarbons (TAH) or total aqueous hydrocarbons (TAqH). Results from the monitoring wells and well points varied, however most of the samples had contaminant results in excess of their applicable standard; either AWQS or Table C. Activities proposed for the 2018 field season generally consist of continuing surface water and pad porewater monitoring.
|
Joshua Barsis |
| 8/5/2019 |
Document, Report, or Work plan Review - other |
Reviewed a document titled 2018 Contaminated Sites Monitoring Report and 2019 Work Plan, dated July 18, 2019 for the BPX Crude Oil Topping Unit South site. This report includes a description of the 2018 field effort, along with a work plan for 2019 activities.
Field activities were completed in August 2018 and generally consisted of surface water and pad porewater monitoring. Analytical samples were collected and submitted for laboratory analysis from 27 monitoring wells and well points (11 of which are considered closely connected with surface water) and from 12 surface water locations.
The results from surface water Sample SW8 (12.5 µg/l) exceeded the Alaska Water Quality Standards (AWQS) for total aromatic hydrocarbons (TAH). None of the other samples collected from surface water exceeded the AWQS for TAH or total aqueous hydrocarbons (TAqH). However a sheen was documented at surface water Sample SW12, which is also an exceedance of the AWQS. Results from the monitoring wells and well points varied, however most of the samples had contaminant results in excess of AWQS or Table C Groundwater Cleanup Levels. Activities proposed for the 2019 field season generally consist of continuing surface water and pad porewater monitoring, and replacement of damaged wells.
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Joshua Barsis |
| 7/26/2021 |
Document, Report, or Work plan Review - other |
2020 Contaminated Sites Monitoring Report and 2021 Work Plan |
Andrea Carlson |
| 2/25/2022 |
Document, Report, or Work plan Review - other |
2021 Contaminated Site Monitoring Report and Proposed Work Plan |
Andrea Carlson |
| 7/29/2022 |
Offsite Soil or Groundwater Disposal Approved |
Thirty cubic yards of contaminated gravel fill were approved for disposal and the Hilcorp Grind and Inject facility. Contaminated gravel waste was generated during the secondary containment expansion construction project to the southwest of the COTU bulk fuel storage tanks. A sample collected from the waste underwent the TCLP and was analyzed for benzene. The result was 0.012 mg/L. Hilcorp changed construction plans and will now construct the expansion on top of the pad to eliminate disturbance of the pad in the contaminated area. |
Lisa Krebs-Barsis |
| 11/14/2023 |
Document, Report, or Work plan Review - other |
Reviewed the 2022 Contaminated Sites Monitoring Report and Proposed Work Plan, dated January 31, 2023.
Water quality monitoring activities were completed in July 2022 and consisted of collecting water from four surface water locations including SW-1, SW-8, SW-10, and SW-12.
The surface water samples were submitted to the laboratory for analysis of benzene, toluene, ethylbenzene, and total xylene (BTEX) and poly-cyclic aromatic hydrocarbons (PAHs) and compared to the Water Quality Standards (AWQS) for total aromatic hydrocarbons (TAH) and total aqueous hydrocarbons (TAqH). The surface water samples from three locations had detections of benzene, but the calculated concentrations of TAH and TAqH did not exceed the AWQS.
The site workplan details continued biennial sampling of the four surface water locations with the addition of a fifth surface water sampling location (SW-6) to evaluate detections of benzene on the south side of the site. The DEC concurs with the continued sampling and the additional sample location.
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Andrea Carlson |
| 10/3/2024 |
Document, Report, or Work plan Review - other |
DEC reviewed and approved the COTU South 2023 Contaminated Site Monitoring Report and Proposed Work Plan received February 14, 2024. Water quality monitoring activities consisted of collecting water from five surface water locations: SW-1, SW-6, SW-8, SW-10 and SW-12. The surface water samples were submitted to the laboratory for analysis of benzene, toluene, ethylbenzene, and total xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAHs) and compared to the Water Quality Standards (AWQS) for total aromatic hydrocarbons (TAH) and total aqueous hydrocarbons (TAqH). No deviations from the previously approved work plan were necessary. The surface water samples from four of the five locations had detections of benzene, but the calculated concentrations of TAH and TAqH did not exceed the AWQS. The analytical Laboratory Report was not included in the 2023 Contaminated Site Monitoring Report and has been requested as a revised report. |
Laura Jacobs |
