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Site Report: AT&T Alascom Soldotna Microwave

Site Name: AT&T Alascom Soldotna Microwave
Address: 44890 Churchhill Avenue, Mile 3.5 Kenai Spur Hwy., Kenai, AK 99611
File Number: 2320.38.005
Hazard ID: 1004
Status: Active
Staff: Paul Horwath, 9072623422
Latitude: 60.531667
Longitude: -151.083333
Horizontal Datum:NAD83

We make every effort to ensure the data presented here is accurate based on the best available information currently on file with DEC. It is therefore subject to change as new information becomes available. We recommend contacting the assigned project staff prior to making decisions based on this information.


During the removal of two regulated underground storage tanks (USTs) and one non-regulated UST (heating oil), diesel contaminated soils were encountered at the non-regulated UST excavation. Approximately 100 cubic yards of petroleum contaminated soil were removed and stockpiled. Petroleum contamination remains beneath an auto shop. No site work done in 2005.

Action Information

Action Date Action Description DEC Staff
12/1/1992 Site Added to Database Diesel contamination. No Longer Assigned
12/1/1992 Site Ranked Using the AHRM Insufficient comments provided to allow proper audit of scoring method. No Longer Assigned
12/10/1992 Preliminary Assessment Approved (Old R:Base Action Code = SA1R - Phase I SA Review (CS/LUST)). Phase 1 site assessment review. Don Fritz
12/20/1992 Site Characterization Report Approved (Old R:Base Action Code = SA2R - Phase II SA Review (CS)). Phase 2 site assessment review. Don Fritz
4/15/1993 Update or Other Action (Old R:Base Action Code = RAPR - Remedial Action Plan Review (CS)). Remedial action plan review. Don Fritz
8/15/1993 Update or Other Action (Old R:Base Action Code = RARR - Remedial Action Report Review (CS)). Remedial action report review. Don Fritz
2/27/2003 Update or Other Action Responsible Party field changed based on new information from PacificCorp Environmental Remediation Company. Elizabeth Stergiou
1/23/2004 Update or Other Action File number assigned and entered into the Fileroom DB and CS DB. Alyce Hughey
7/28/2005 GIS Position Updated Using Figure 2-2 from a Preliminary Assessment Report Soldotna Radio Relay Site, from Superfund Technical Assessment and Response Team, Dated September 1999, in conjunction with TopoZone Pro and KPB Parcel Lookup, entered the coordinates for this site. Metadata include No Topo Basemap, TopoZone Pro Street Map, Black and White Aerial Photo, on a Medium Size Map, View Scale 1:10,000, Coordinate Datum NAD83. High degree of confidence in accuracy of location. Alyce Hughey
8/1/2005 Update or Other Action Sent an e-amil to the PacifiCorp's project manager inquiring on the status of any work to be conducted in 2005. Donald Seagren
12/16/2005 Update or Other Action Have received no response to previous e-mails. Sent e-mail requesting project status update and submission of work plans to achieve site closure in 2006. Donald Seagren
12/27/2005 Update or Other Action John Aniello is the new PM for PERCO. Sent John summaries of both LUST and CS issues remaining at the site for assessment and cleanup that would lead to site closure. Requested work plan submittal for work to be conducted in 06. Donald Seagren
7/26/2006 Site Characterization Workplan Approved Review and approve work plan for installing additional MWs and conducting additional site assessment. Requested the addition of BTEX analyses to the initial GW sampling event. If the results are the same as other wells, where GRO & BTEX are not a concern in the groundwater, it can be dropped from further sampling events, until final closure sampling. Donald Seagren
2/9/2007 Site Characterization Report Approved Reviewed the 2006 assessment report. DRO contaminated soil occurs in the GW plume source area from ground surface to a depth of about 25' where a silt layer restricts further vertical migration. The GW is perched, generally >3' thick saturated zone, occurs at the contact between the overlying clean sand and an underlying silt. A groundwater divide transects the site. The DRO plume underlying the equipment Building and surrounding areas is approximately 220' X 100'. A measurable thickness of LNAPL is not present even though DRO concentrations range up to 36,000 ug/l in the source area. Natural attentuation is on-going but perhaps not sufficient to control plume migration. The sites infrastructure of buildings, piping, cables, etc. is a limiting factor in what remediaton and cleanup efforts can be accomplished. Currently the plume is not migrating off site or affecting the deeper confined drinking water aquifer. Additional assessment, monitoring, and corrective actions are being evaluated. Donald Seagren
2/9/2007 Exposure Tracking Model Ranking Donald Seagren
9/5/2007 Interim Removal Action Approved Approved the 2007 Interim Cleanup Plan - Shallow Soils, dated August 27, 2007. If unused fuel lines/culverts are encountered, they will be removed, cleaned and disposed of at the Kenai Peninsula Borough's Soldotna landfill. The work is tentatively scheduled for mid-September 2007. Any contaminated soils encountered will be treated either by on-site bio-treatment for the lower level contaminated soils, or thermally treated at ASR in Anchorage for the higher level contaminated soils. A separate plan will be developed to address the deeper conntaminated soils and groundwater. Donald Seagren
9/14/2007 Update or Other Action Telephone call from Alex Tula with AltaGeosciences. They will begin shallow soil excavation work on Monday, September 17, 2007. Once that phase is completed a bio-venting system will be installed later in 2007. Donald Seagren
10/2/2007 Cleanup Plan Approved Approved Interim Cleanup Plan - Deeper Vadose Zone Soils. The proposed remediation will be by a conbination of SVE and Bioventing, and will address the zone below shallow soils removal (approximately 10' bgs) down to a low permeability silt layer or perched GW (if present) that is approximately 30' bgs. The system will be first operated as an SVE system to strip the aromatic fractions. When that phase stabilizes, the pump will be reversed to a bioventing mode to stimulate bioremediation of the soils by providing oxygen to the soil bacteria. The system will be installed mid to late October 2007. It will only be operated during periods of above freezing weather, approximately May thru October. Donald Seagren
4/1/2008 Update or Other Action The 2007 GW monitoring data suggest that relatively slight differences in GW elevations may significantly affect GW flow directions. A topographic high in the silt underlying the perched aquifer forms a dry zone east of the Equipment Bldg, which the perched aquifer is forced to flow around. Water levels in 2007 are lower than in 2006, and consequently, the dry zone has increased in area and now extends beneath the Equipment Bldg. The expanded dry zone has forced GW flowing through the DRO plume source area to flow more northerly toward well MW-9 which did not contain detectable DRO concentrqations in 06. Low GW levels resulted in the first measurable LNAPL occurrence at the site, which disappeared as water levels rose to more typical levels. A passive skimmer has been installed in this well to recover any free product should this re-occur. Donald Seagren
6/12/2008 Update or Other Action Site transferred from Don Seagren to Paul Horwath per Linda Nuechterlein. Alyce Hughey
6/12/2009 Report or Workplan Review - Other Reviewed the 2008 Groundwater Monitoring Report Soldotna Repeater Site, from ALTA Geosciences, Inc., dated May 2009 for Paul Horwath and prepared a summary for his review and oversight. During the two 2008 groundwater monitoring events there has been an increase in DRO groundwater concentrations. A pre-existing dry zone at the site has formed a topographic high in the underlying silt which continued to expand in 2008 as water levels continued to fall in most of the wells. The expanded dry zone has resulted in unexpected groundwater flow directions and has shifted the DRO plume to the north. The DRO concentrations have increased within the source area and down-gradient areas in response to the lower water levels. Sheens are now present within wells that previously didn’t contain sheens before, and wells are detecting DRO were previously didn’t detect DRO. Alyce Hughey
6/16/2009 Report or Workplan Review - Other Reviewed the Monitoring Well MW-15 Installation Report,dated April 23, 2009, from ALTA Geosciences, Inc. for Paul Horwath and prepared a summary for his review and oversight. The installation of the additional monitoring well MW-15 was installed to assess the groundwater conditions down-gradient from MW-9, which contained elevated concentrations of DRO in 2007. Due to the lower water table in 2008, and the change in groundwater flow direction, no groundwater samples were obtained from MW-15 due to the well being dry. The soil screening done at the time of the well installation did not show any evidence of hydrocarbon impacted soil within the well boring. Alyce Hughey
5/11/2010 Meeting or Teleconference Held Meeting with AT&T Inc., ALTA Geosciences and ADEC staff (Paul Horwath and Alyce Hughey) to discuss the Work Plans for the 2010 field season and any project updates. Alyce Hughey
7/6/2010 Report or Workplan Review - Other Reviewed the 2009 Groundwater Monitoring Report, dated April 2010, from ALTA Geosciences, Inc. for Paul Horwath. During the two 2009 groundwater monitoring events there has been a decrease in DRO groundwater concentrations, with a decline in the overall water levels within the monitoring wells, causing a change in the dry zones and the overall groundwater flow path at the site. With the change in groundwater levels the DRO plume shifted from a north/southerly direction to an east/westerly direction. The bioventing/soil vapor extraction system was in operation from May 15th until October 31st, with product recovery from MW-11 using absorbent socks recovering approximately 6.2 ounces in 2009. Alyce Hughey
9/10/2010 Site Characterization Workplan Approved Approved the In Situ Chemical Oxidation Work Plan, dated August 8, 2010, from Alta Geosciences, Inc. Paul Horwath
4/6/2011 Report or Workplan Review - Other Reviewed the 2010 Groundwater Monitoring Report, Soldotna Repeater Site, dated January 2011, from ALTA Geosciences, Inc. During the two 2010 groundwater monitoring events there has been an increase in DRO groundwater concentrations, with a continual decline in the groundwater levels within the monitoring wells. Three additional monitoring wells were found dry, MW-12, MW-13 and MW-14 for a total of six wells now being found dry. Two monitoring wells were decommissioned, MW-1 due to the poor recharge rate and MW-11 provides a good monitoring point for characterizing the groundwater in this area, and MW-4 was decommissioned because it was broken. Approximately 3.9 ounces of product was recovered from MW-11 using absorbent socks during 2010 with a total of approximately 112 ounces (0.88-gallons). Alyce Hughey
5/11/2011 Meeting or Teleconference Held Meeting with AT&T Inc., ALTA Geosciences, Iberdrola Renewables Holdings, Inc. and ADEC staff (Paul Horwath and Alyce Hughey) to discuss the Work Plans for the 2011 field season and any project updates. Alyce Hughey
6/2/2011 Report or Workplan Review - Other Reviewed the 2009 Site Investigation Report, dated September 2010 from ALTA Geosciences. In September of 2009 to better define the top of the perching silt layer and the potential groundwater flow directions, twelve soil borings were advanced and the soils were characterized. Findings shows that groundwater is currently confined to areas that follows a turning and winding course between topographic highs in the perching layer, indicating that once the plume migration route was blocked, the DRO concentrations in groundwater quickly declined. Also, the dissolved DRO migrating with groundwater apparently does not tend to partition to the soil and/or the site’s natural attenuation processes are highly effective, and it is suggested that the original source area has the residual contamination that serves as a continuing source to the groundwater plume. It is also thought that if the two dry zones are connected, the groundwater plume may be forced to flow south-ward around the dry zone with a southwesterly migration flow pattern. In addition the thought that if the water level does rise in the future, the DRO migration route would be expected to reverse the course followed over the past several years, and expected to first travel north then northwesterly. Alyce Hughey
5/18/2012 Meeting or Teleconference Held Meeting with Paul Horwath, Alex Tula with ALTA GeoSciences and Larry Bamberger with AT&T at the Soldotna ADEC office to discuss the current site conditions. Discussed the decreasing groundwater levels over the past few years, and interested to see what the groundwater levels are for this year due to the high snow fall in the winter of 2011 and 2012. Product recovery has stopped due to decrease in recovery efforts. On-going remediation is performed in the spring and summer. Groundwater monitoring conducted semi-annually and may go to annual. No significant changes were observed from the sodium persulfate treatment. Alyce Hughey
6/18/2012 Report or Workplan Review - Other Reviewed the 2011 Groundwater Monitoring Report Soldotna Repeater Site, dated April 2012, prepared by ALTA Geosciences, Inc. Three groundwater monitoring events were performed in 2011. One was conducted on January 18, 2011 as a follow-up of the chemical oxidant treatment performed in 2010, where an increase was observed in MW-6 at 64.7 mg/L DRO. The semi-annual groundwater sampling events were conducted on June 7, 2011 and September 28, 2011. Groundwater concentrations remain consistent other than within wells MW-6 and MW-11, with MW-6 detecting DRO at 16.7 mg/L in June and 24 mg/L in September, and MW-11 detecting 101 mg/L in June and LNAPL in September. No change in the dry zone was observed in 2011 with monitoring wells MW-9, MW-10, MW-12, MW-13, MW-14 and MW-15 remaining dry. The soil vapor extraction system was operating on a continual basis between March of 2011 and November 15, 2011. Product recovery was discontinued in March of 2011 within MW-11, and an increase in DRO concentrations was observed in the well with LNAPL present in September with 0.01 feet of product. Alyce Hughey
5/31/2013 Report or Workplan Review - Other Reviewed the 2012 Groundwater Monitoring Report, Soldotna Repeater Site, dated April 2013, prepared by ALTA Geosciences, Inc. Two groundwater monitoring events were performed during 2012, one on June 11, 2012, and one on October 9, 2012. An additional groundwater level measurement was performed on May 16, 2012, and MW-2 was sampled again on March 25, 2013 after DRO was detected above the groundwater cleanup levels. The groundwater levels rose in 2012, reversing the downward trend that occurred from 2006 until 2011. The groundwater levels rose by 1.0 to 5.9 feet between September of 2011 and October of 2012. DRO was detected for the first time in October of 2012 in MW-2 at a concentration of 2.370 mg/L. This well was re-sampled in March of 2013 with DRO not being detected. MW-6 remains above the groundwater cleanup levels at concentrations of 27.8 and 35.7 mg/L, as well as MW-11 at 37.20 mg/L in October. MW-11 was not sampled in June due to LNAPL, with a total of 0.09 ft of product. Approximately 3.3 ounces was recovered in 2012 for a total of 102.3 ounces (0.8-gallons) of LNAPL has been recovered between 2007 and 2012. Monitoring well MW-6 and MW-11 were also analyzed for BTEX, TOC and PAH’s. MW-6 detected benzene at 0.00429 mg/L, just below the ADEC groundwater cleanup levels. PAH’s were detected in both monitoring wells, but well below the ADEC groundwater cleanup levels, and TOC was detected at 52.5 and 132 mg/L. The soil vapor extraction system was operating on a continual basis between April 30, 2012 and October 23, 2012. Alyce Hughey
6/21/2013 Meeting or Teleconference Held Meeting with ALTA Geosciences and ADEC staff (Paul Horwath and Alyce Hughey) to discuss the current site conditions and proposed work plans for the 2013 field season. Alyce Hughey
7/15/2013 Site Characterization Workplan Approved Reviewed and approved a work plan to install one additional GW monitoring well, in the effort to better define the downgradient extent of groundwater contamination within the affected, perched aquifer. Paul Horwath
9/17/2013 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 71983 Underground Fuel Lines. Paul Horwath
5/6/2014 Report or Workplan Review - Other Reviewed the Well Installation and Decommissioning Report, dated February 28, 2014, prepared by ALTA Geosciences, Inc. On October 22, 2013 before drilling, the site monitoring wells were inspected. Monitoring well MW-3 was found to be completely jacked out of the ground due to frost heaving, and MW-5 was knocked over slightly. Monitoring well MW-3 was decommissioned and MW-5 was straightened and the concrete pad was replaced. Replacement well, MW-3R was installed and MW-17 was installed adjacent to MW-5 because recent gauging showed that water levels are significantly above the screened interval. MW-16 was installed in order to better define the down-gradient extent of hydrocarbon-impacted groundwater. One soil sample was collected in the soil boring of MW-16 and analyzed for DRO, with DRO not being detected. Groundwater samples collected on October 29, 2013 detected DRO at 2.53 mg/L in MW-16, and DRO not being detected in MW-3R and MW-17. Alyce Hughey
5/6/2014 Meeting or Teleconference Held DEC staff Paul Horwath and Alyce Hughey met with Alex Tula, with ALTA Geosciences and Mark Smith, representing AT&T to discuss the upcoming 2014 field work of groundwater monitoring, and the DRO concentrations in newly installed MW-16. Alyce Hughey
5/8/2014 Report or Workplan Review - Other Reviewed the 2013 Groundwater Monitoring Report Soldotna Repeater Site, dated April 2014, prepared by ALTA Geosciences, Inc. The two scheduled groundwater monitoring events were performed on June 19, 2013, and September 24, 2013. Two additional sampling events occurred in 2013, one on March 25, 2013 from MW-2, and one on October 29, 2013 from the three newly installed monitoring wells MW-3R, MW-16, and MW-17, with an additional gauging on December 5, 2013. DRO groundwater sample results for June 2013 were 2.64 to 58.4 mg/L, for September 2013 were 2.22 to 5.51 mg/L and in October 2013 from newly installed MW-16 with DRO at 2.53 mg/L. MW-11 had a total of 2.3 ounces of LNAPL was recovered from absorbent socks in 2013, for a total of 104.5 ounces (0.81 gallons) have been recovered between 2007 and 2013. The soil vapor extraction system was operating on a continual basis between May 1, 2013 and November 20, 2013. The groundwater was at significant highs in 2013, with MW-10 having water in it for the first time since 2007, MW-15 had water in it for the first time, and the dry zone appears to be completely inundated due to the rising water levels. Alyce Hughey
9/23/2015 Report or Workplan Review - Other Reviewed the 2014 Groundwater Monitoring Report, dated June 2015, prepared by Alta Geosciences in association with Kent & Sullivan, Inc. Groundwater elevations higher so a larger perched aquifer present at the site than a couple years ago. Mostly a DRO plume that seems stabile, or diminishing. Paul Horwath
5/26/2016 Meeting or Teleconference Held Meet with AT&T's consultant, Alex Tula, with Alta Geosciences, Incorporated, in order to review action in 2015, and work planned in 2016. Paul Horwath
4/24/2017 Update or Other Action Received Alta Geosciences, Inc. 2016 Groundwater Monitoring Report, dated March 2017. Paul Horwath

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