Site Report: Chugach Electric Raspberry Substation
| Site Name: | Chugach Electric Raspberry Substation |
|---|---|
| Address: | 7020 Caravelle Drive, Anchorage, AK 99502 |
| File Number: | 2100.38.549 |
| Hazard ID: | 26275 |
| Status: | Cleanup Complete - Institutional Controls |
| Staff: | IC Unit, 9074655229 dec.icunit@alaska.gov |
| Latitude: | 61.157220 |
| Longitude: | -149.967434 |
| Horizontal Datum: | WGS84 |
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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.
Problems/Comments
On January 14, 2014 Chugach Substation personnel identified a low fluid level inside the Load Tap Changer (LTC) compartment of Raspberry Substation Transformer (TRF-178). Upon further review it was found that a sampling port was left open during maintenance activities. It is suspected that the secondary ball valve was moved to the open position from falling snow and ice. A new ball valve has since been installed in the horizontal position to keep this from occurring. An estimated 150 gallons of Non-PCB mineral oil spilled onto the ground directly below the sampling port of the transformer. The mineral oil affected a 30 square foot area on the ground surface along the concrete structural pad of transformer TRF-178 and an estimated 100 square foot area below surface. A 10 foot high fence secures the spilled area within Chugach Electric Raspberry Substation. Cleanup operations were conducted in July, 2014 to coincide with planned Raspberry Substation de-energization upgrades that required excavation activities. Analysis of July 02, 2014 confirmation samples identified diesel range organics (DRO) were above state cleanup levels around the foundation of transformer TRF-178. Removal of the remaining contamination was not feasible without damaging the structural stability of the transformer and adjacent switch gear foundations. High nitrogen fertilizer was added to the excavation prior to back filling and an impermeable barrier was installed around the transformer foundation base. The impermeable barrier is the base of a secondary containment structure that was installed at this location on August 5, 2014. A total of 30.79 tons of mineral oil-contaminated soil were thermally treated. Two areas of contamination adjacent to the spill source did not meet state of Alaska minimum cleanup standards: DRO at 17,000 mg/kg, 45 inches/3.75 feet, Lab ID# 1142878004, location from Source Center; and DRO at 10,000 mg/kg, 18 inches/ 1.5 feet, LabID# 1142878008, location High Bench TRF.
Action Information
| Action Date | Action | Description | DEC Staff |
|---|---|---|---|
| 8/22/2014 | Potentially Responsible Party/State Interest Letter | State Interest / Intra-department Transfer letter issued by PERP staff Mark Sielaff. | Mitzi Read |
| 9/3/2014 | Spill Transferred from Prevention Preparedness and Response Program | Spill transferred by PERP staff Mark Sielaff. Spill no. 14239901401; spill date = 1/14/14; substance = non-PCB transformer mineral oil; quantity = ~150 gallons; source = sampling port on load tab changer on main transformer (TRF-178). | Mitzi Read |
| 9/23/2014 | Site Added to Database | A new site has been added to the database | Mitzi Read |
| 9/24/2014 | Exposure Tracking Model Ranking | Initial ranking with ETM completed for source area id: 79662 name: 150 Gal Non-PCB Mineral Oil - Transformer TRF-178 | Mitzi Read |
| 9/29/2014 | Exposure Tracking Model Ranking | A new updated ranking with ETM has been completed for source area 79662 150 Gal Non-PCB Mineral Oil - Transformer TRF-178. | Joshua Barsis |
| 10/2/2014 | Potentially Responsible Party/State Interest Letter | CSP sent a letter of state interest on this day. | Joshua Barsis |
| 10/2/2014 | Document, Report, or Work plan Review - other | The CSP reviewed the July 28, 2014 Mineral Oil Release – Final Report, pertaining to this site. During cleanup, 30.79 tons of impacted soils were removed and treated at Alaska Soil Recycling (ASR). Soil samples collected from the base of the excavation exhibited varying levels of diesel range organics (DRO) up to a maximum concentration of 17,000 mg/kg at roughly four feet below ground surface (bgs). The vertical and horizontal extent of contamination was not defined. CSP requested a work plan by November 14, 2014 to delineate the nature and extent of any remaining soil contamination and evaluate the potential migration of contaminants to groundwater. | Joshua Barsis |
| 11/14/2014 | Document, Report, or Work plan Review - other | Reviewed the Site Characterization Work Plan, dated November 2014 for the Chugach Electric Raspberry Substation site. CSP has no objections to the work plan. | Joshua Barsis |
| 1/9/2015 | Document, Report, or Work plan Review - other | Reviewed the Site Characterization Report, dated January 2015. Three soil boring were advanced to roughly 30 feet below ground surface (bgs) in November 2014 to better delineate the extent of contamination. The borings were placed to the north (CRS-1), west (CRS-2), and south (CRS-3) of the Raspberry Substation, and outside the fenced area to avoid buried utilities. Each boring consisted of a primarily dense silt and clay material. A sand layer was encountered in Boring CRS-2 at about 29.5 feet bgs. The sand layer was dark, coarse, and dry, with wood-like debris interspersed throughout. Two samples were collected from each boring and were analyzed for DRO and RRO. DRO and RRO were only present in one sample collected from approximately 30 feet bgs in Boring CRS-2; however, both DRO and RRO were below the most stringent ADEC MTG cleanup levels. None of the other samples exhibited DRO or RRO above the laboratory detection limits. Groundwater was not encountered in any of the borings. | Joshua Barsis |
| 1/9/2015 | Exposure Tracking Model Ranking | A new updated ranking with ETM has been completed for source area 79662 150 Gal Non-PCB Mineral Oil - Transformer TRF-178. | Joshua Barsis |
| 1/23/2015 | Cleanup Complete Determination Issued | Petroleum contamination remains in surface and sub-surface soil above ADEC cleanup levels; however, ADEC has determined there is no unacceptable risk to human health or the environment as long as the contamination is properly managed. Please see the file for more information. | Joshua Barsis |
| 1/23/2015 | Institutional Control Record Established | Institutional Controls established and entered into the database. | Joshua Barsis |
| 2/3/2015 | Update or Other Action | Received attachment A: IC Agreement Page | Joshua Barsis |
| 10/6/2016 | Institutional Control Compliance Review | IC compliance review conducted. Staff changed from Joshua Barsis to IC Unit. Information added to Closure/IC Details. Reminder system set to follow-up every five years. | Kristin Thompson |
| 6/17/2020 | Institutional Control Compliance Review | An IC compliance review was conducted on this date and a reminder letter of the current site conditions was issued to the responsible party on record with the landowner CC'd. The next compliance review will occur in five years, in 2025. | Cascade Galasso-Irish |
Contaminant Information
| Name | Level Description | Media | Comments |
|---|---|---|---|
| DRO | > Human Health/Ingestion/Inhalation | Soil |
Control Type
| Type | Details |
|---|---|
| Notice of Environmental Contamination | |
| Signed CS Determination |
Requirements
| Description | Details |
|---|---|
| Advance approval required to transport soil or groundwater off-site. | Standard condition. |
| Movement or use of contaminated material (including on site) in a manner that results in a violation of the water quality standards is prohibited (18 AAC 70) | Standard condition. |
| Groundwater Use Restrictions | Installation of groundwater wells requires ADEC approval. |
| Periodic Review | CEA shall report to ADEC every 5 years to document land use, or report as son as CEA becomes aware of any change in land ownership and/or use, if earlier. |
| When Contaminated Soil is Accessible, Remediation Should Occur | Contamination remains in the sub-surface soils at this site above ingestion, inhalation, and MTG cleanup levels; however, further excavation is impractical due to buried utilities and other structural components. When the contaminated soil becomes accessible, the soil must be evaluated and contamination addressed in accordance with an ADEC approved work plan; and/or to the satisfaction of ADEC. |
No associated sites were found.