State of Oregon Department of Environmental Quality

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1 State of Oregon Department of Environmental Quality Memorandum To: Rich Muza, US Environmental Protection Agency, Region 10 Date: April 5, 2013 Through: From: Subject: Keith Johnson, NWR Cleanup Manager Jim Anderson, Portland Harbor Manager Dan Hafley, Project Manager Alex Liverman, Stormwater Coordinator Source Control Decision PacifiCorp Knott Substation ECSI #5117 PacifiCorp completed source control related investigation and facility upgrades for the active PacifiCorp substation property referred to as the Knott Substation. The site consists of one city block located in a mixed residential/commercial area, and located approximately 3,500 feet east of the Willamette River in Portland. Source control work at the property was completed under a Voluntary Agreement signed with DEQ in January 2009, which included investigation at a number of former or current PacifiCorp properties in the vicinity of river mile 11 east (RM 11E) of the Portland Harbor Superfund Site. All but the Knott Substation are located in close proximity to the river, and are addressed in a separate source control decision document. Knott Substation was included in PacifiCorp s source control work because it is an active substation in the RM 11E area, and because stormwater in the substation area drains to the City of Portland stormwater system that formerly discharged to the river at Outfall 44A. Stormwater from the substation area is now diverted to a City of Portland treatment facility. Based on our review of site documents, DEQ concludes that the Knott Substation is not a current or likely future source of contamination to the Willamette River. Site Description and History Knott Substation is located west of NE Rodney Ave., between NE Russell St. and NE Knott St., in Portland, Oregon (see Attachment 1 for location). The Knott Substation covers approximately 2.74 acres. The substation is an unmanned electricity transmission and distribution substation where incoming 115 kilovolt (kv) and 57 kv transmission lines are stepped down to 11 kv and 12 kv for distribution to residential, commercial, and other customers in the area. The substation is generally flat, but partially terraced at the equipment pads. The land slopes gently to the south/southwest with the elevation ranging from 169 feet in the northeast corner of the substation to 160 feet in the southwest corner along NE Russell St.

2 Page 2 of 8 The substation is covered with gravel, except for areas covered by two buildings and concrete pads used to support electrical equipment. Gravel is placed on the ground surface at substations as a safety measure and is typically 3 to 12 inches thick. The entire site perimeter is fenced. One building is located on the north side of the substation (see Attachment 2 for site features). The building is referred to as the Substation Building. It is a three-story concrete and brick building that serves as the current control house for the substation. A second smaller building was formerly located to the east of the Substation Building. This building, historically referred to as the Control House, was demolished in An additional small building is located on the south side of the substation and contains switchgear for the 12 kv yard. The facility currently houses three substation yards referred to as the 115 kv Yard located southeast of the Substation Building, the 57 kv Yard located west of the Substation Building, and the 12 kv Yard located on the south side of the property. A 4kV yard was formerly located in the northeast corner of the Substation property (along NE Knott St.). That yard is no longer in service and the equipment was removed in the early 1990s. Portland General Electric owned and operated the substation between 1906 and In 1973, the substation was transferred to PacifiCorp as part of a larger exchange of properties and service territories between the two companies. The exchange agreement was approved and ordered by the Oregon Public Utility Commission on December 15, 1972; the transfer was completed in The substation was expanded in 1977 when two adjoining tax lots in the southeast corner of the site were purchased, though no electrical operations have been conducted on those parcels. Over the course of substation operation, electrical equipment containing polychlorinated biphenyls (PCBs) have been present at the site. Prior to the 1990s, on-site capacitors contained PCBs in excess of 500 milligrams/liter (mg/l). As part of PacifiCorp s retrofilling program, equipment with higher concentrations of PCBs were either replaced or refilled with dielectric fluid with lower levels (or no) PCBs. At present, no site equipment has PCBs in excess of 50 mg/l. Two dry wells were formerly located on-site to manage stormwater runoff in the substation interior, but were later decommissioned and replaced with an on-site infiltration basin. No interior catchbasins were or are present that discharge to the local stormwater system. There are City of Portland catchbasins within the streets bounding the site that are part of the stormwater collection system that formerly discharged at Outfall 44A. Catchbasin locations are shown in Attachment 3. Since 2011, area stormwater has been diverted to the City of Portland East Side CSO Tunnel for treatment at the Columbia Boulevard wastewater treatment facility. There is no on-site storm water collection system that discharges to the City s municipal system. Rainfall infiltrates the substation gravel, and there is no overland surface flow off of the site. In 2011, an infiltration basin was constructed within the substation interior to manage stormwater runoff. Prior to construction, soil sampling was performed with DEQ oversight to confirm that the infiltration area was free of contamination. Sampling results are discussed below. Regulatory History Two stormwater dry wells, defined as Class 5D2 Underground Injection Control (UIC) structures, were formerly located on-site. Both were decommissioned by PacifiCorp in The dry wells were formerly used for on-site infiltration of stormwater associated with the 57 kv

3 Page 3 of 8 Yard located in the west area of the substation. The locations of these former structures are shown in Attachment 2. Dry Well #1 (DEQ UIC # ) received drainage from the active 57 kv Yard area (approximately 1 acre total drainage area). Dry Well #2 (DEQ UIC # ) was a much smaller structure located directly east of the 57 kv Yard area, and drained an area of approximately 0.01 acres. The UIC structures were investigated by PacifiCorp in The scope of the investigations included sampling and analysis of sediment and water collected from the two dry wells and from a catch basin located near Dry Well #2 that ultimately drained to Dry Well #1. At the time of the investigation, however, no sediment was present in either dry well, and only Dry Well #1 contained any water. Consequently, sampling and analysis was limited to sediment and water from the catch basin and water only from Dry Well #1. Catch basin sediments were found to contain detectable levels of PCBs, phthalates, polynuclear aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), metals, and total petroleum hydrocarbons (TPH). Aroclor 1260 was detected at milligrams/kilogram (mg/kg) in the sediment sample, and mg/l in water. Selected metals and semi-volatile organic compounds were also detected. Based on sampling results and dry well construction, groundwater impacts from dry well use appeared unlikely. DEQ approved the workplan for closure of the UICs in a letter to PacifiCorp dated May 10, PacifiCorp performed the closure work in accordance with approved methodologies on September 6, No underground storage tanks are known to be present on-site, nor are there any known regulatory permits for the site related to air, water, or hazardous waste. Hazardous Substance Releases The following information was provided by PacifiCorp regarding hazardous substances releases at Knott Substation: According to a February 2007 Spill Close Out Report, the northernmost of the three 115 kv to 57 kv transformers in the 115 kv Yard had experienced weeping-type leaks onto the concrete pad and gravel adjacent to the pad over a number of years. PacifiCorp observed staining of the substation gravel east and south of the transformer after a period of heavy rainfall. The oil in this transformer contained 2.9 mg/kg PCBs based on a sample collected in June of A previous sample collected from this transformer in 1984 contained 3 mg/kg PCBs. PacifiCorp repaired the leaking gasket and seams; cleaned the concrete pad; and removed visibly stained gravel and the surface (top several inches) of the underlying native soil from an area east and south of the transformers, and from a small area near the south side of the substation. Approximately 17 tons of gravel and soil were transported off-site to Hillsboro Landfill; the gravel was replaced. No soil samples were collected prior to or after the cleanup. On May 21, 1997, transformer T3443, one of the two easternmost transformers in the 57 kv Yard, caught on fire; the flames damaged transformer T3435, the second of the two easternmost transformers. The City of Portland fire department responded to the fire and sprayed foam on the burning equipment and allowed it to burn out over a period of about 5 hours. According to PacifiCorp, no water was applied to the fire and the transformer oil was consumed in the fire. Electrical equipment sampling records provided by PacifiCorp indicate that in 1984 the PCB

4 Page 4 of 8 concentration in transformers T-3435 and T-3443 were 3 mg/l and 31 mg/l, respectively. No soil samples were collected after the fire. During a visit to the site in July 2008, PacifiCorp found that a tar-like oil had leaked from cables near the transformer in the 57 kv Yard that had caught on fire. Oil was observed on the concrete pedestals and the ground. The concrete was removed and disposed off-site. No PCBs were detected in a wipe sample collected from the concrete. During the same site visit, two minor releases onto concrete surfaces were identified: 1) a small leak of insulating oil from a 675 gallon above-ground storage tank located in an alcove next the Control House (a sample of the oil was found to contain 15 mg/l PCBs) and 2) drips of a tar-like oil onto the floor in the Substation Building (no PCBs were detected in a wipe sample collected from the concrete floor). The concrete surfaces were cleaned at both locations. To further evaluate if the site had reported spills or releases, or if surrounding properties had suspected or confirmed releases that could impact the Knott Substation, PacifiCorp obtained and reviewed an Environmental Data Resources (EDR) Radius Search Report. The radius search report did not reveal any reported releases at the Knott Substation or neighboring properties with suspected or confirmed releases that have the potential to impact the Knott Substation. Investigation Results Onsite There is no record of environmental sampling at the substation prior to Recent soil sampling was completed as follows: Infiltration basin related work; 4kV Yard sampling associated with substation modernization; Central Yard sampling associated with substation construction; and Perimeter sampling completed at the request of DEQ. Each sampling event and results are discussed below. Sample locations are shown in Attachment 4. Compiled analytical results for PCBs are presented in Attachment 5. Infiltration Basin. Following dry well abandonment, an infiltration basin was constructed on-site to manage stormwater. Under a work plan approved by DEQ, five near-surface soil samples were collected in the infiltration area in January 2011and analyzed for PCBs. None were detected. In August 2011, three additional samples were collected along the location of a subsurface pipe associated with the infiltration basin. PCBs were detected in one sample to mg/kg. Also in August, a small area of visually-impacted soil was found. PCBs were detected to mg/kg prior to removal of the soil; confirmation samples did not contain detectable PCBs. TPH were detected in confirmation samples to 5,088 mg/kg. 4kV Yard. In August 2011, samples were collected from the northeast corner of the substation, formerly known as the 4kV Yard. Soil samples were collected from below substation gravel and an abandoned concrete pad. PCBs were detected in soil ranging from to 0.64 mg/kg, and in one of five concrete samples to 0.57 mg/kg. Central Yard. In August 2011, twelve soil samples were collected from below (surface) gravel in the central substation area. These were composited to create four samples for analysis. PCBs were detected at concentrations from 0.02 to 0.28 mg/kg.

5 Page 5 of 8 Substation Perimeter. In 2011, DEQ requested sampling of soil at the substation perimeter, in landscaped areas outside of the fenced facility and adjoining surrounding streets. The purpose of the sampling was to confirm that PCBs had not migrated to adjoining public areas where residential exposure might occur. Nine surface soil samples were collected on the north, east, and south property boundary (the west is developed, with little potential for runoff from the site). Five of nine samples contained detectable PCBs, ranging from to mg/kg. All results are well below DEQ s most conservative residential screening value of 0.2 mg/kg. The low concentrations of PCBs detected in perimeter soil indicate to DEQ that off-site migration is limited and unlikely to pose a significant threat or recontamination concern to the Willamette River. Source Control Investigation Results Offsite PacifiCorp s Knott Substation is located within a former portion of the City s stormwater Outfall Basin 44A. Prior to 2011, stormwater in this area was collected in the municipal stormwater collection system and discharged to the Willamette River through Outfall 44A, located just west of the intersection of N. River St. with N. Randolph Ave. in the Lower Albina industrial district at RM In 2011, the City diverted the majority of stormwater collected in Outfall Basin 44A, including the area around the Knott Substation, into the recently completed East Side CSO Tunnel. Accordingly, stormwater currently conveyed in the City system that originates in the vicinity of the Knott Substation does not directly discharge to the Willamette River. However, limited volumes of stormwater collected throughout the system may overflow to the river during extreme winter events, on average 2.5 times per year. This would not include stormwater from the substation itself, as stormwater does not leave the site. As part of an intergovernmental agreement between the City and DEQ, the City performed stormwater source investigations on a number of outfall basins located within the Portland Harbor Superfund Site. Outfall Basin 44A was included in the City s basin investigations. Under this work, stormwater sediment samples from two catch basin inlets located in the City street adjacent to the Knott Substation along NE Russell St. Both samples were collected on April 8, See Attachment 6 for sampling locations. Catch Basin-ADZ315 is located on the north side of NE Russell St. adjacent to the south driveway entrance into the Substation. This catch basin is most likely to receive sediment-laden runoff from the substation, as well as other properties nearby. Catch Basin-APL263 located at the northwestern corner of the intersection between NE Rodney Ave. and NE Russell St., adjacent to the southeast corner of the substation. The City analyzed each sample for PCB Aroclors, metals, semi-volatile organic compounds (SVOCs), total organic carbon (TOC), total solids, and grain size. Total PCB Aroclors ranged from to mg/kg in CB-APL263 and CB-ADZ315, respectively. Modestly elevated levels of metals and semi-volatile organic compounds including PAHs and phthalates were also detected. At CB-ADZ315, where site-related impacts are most likely to be expected, copper, lead, nickel, and zinc were present in the sediment sample from

6 Page 6 of 8 CB-ADZ315 at 293, 176, 77, and 308 mg/kg. These concentrations are higher than in nearby catchbasin CB-APL263, but not inconsistent with concentrations found in urban catchbasins. Concentrations of phthalates are lower in CB-ADZ315 than other sampling locations within the Outfall 44A stormwater system. Sampling results are included as Attachment 7; note that the PCB concentration shown for catch basin ADZ315 (176 microgram/kilogram) is an error. In their Outfall Basin 44A Source Investigation Report, the City concluded that detected PCBs and other contaminants did not indicate a significant source to the Basin 44A conveyance system. The City further concluded that the PacifiCorp substation did not appear to be a significant contaminant source via overland flows to these catch basins. This determination was based in part on stormwater sampling completed downstream of Knott Substation discussed below. Source Control Evaluation There are three primary mechanisms by which contaminants could be released from the Knott Substation property to the Willamette River. These are: Overland flow; groundwater-to-surface water migration; and stormwater runoff to nearby catch basins. Overland flow does not appear to be a viable pathway given that the site is located approximately 3,500 feet from the Willamette River, and the intervening land is fully developed. Modest concentrations of petroleum hydrocarbons (<5,100 mg/kg) and PCBs (<1 mg/kg) have been detected in site soil; none pose a human health (direct contact) risk, and are below DEQ riskbased concentrations (RBCs) for leaching to groundwater (occupational) with a single exception. Overland flow from the site, if it to occur, would be captured by storm drains in paved streets surrounding the property and is discussed below. Groundwater-to-surface water migration is likewise not a viable pathway. Given the low mobility of PCBs in groundwater, migration over a distance of 3,500 feet is unlikely to occur. In addition, only low levels of PCBs have been detected in site soil, and no free product (such as mineral oil, diesel, or gasoline) has been observed that might facilitate the transport of PCBs. Groundwater is present at 35 or more feet below ground surface. Impacts from soil or shallow dry wells previously located on-site are therefore not expected to have occurred. Transport of PCBs to the river via stormwater infrastructure could have occurred in the past, although site data indicate that any in-stream impacts from the site are expected to be low. As part of Outfall Basin 44A work, the City of Portland sampled stormwater from a downstream manhole (ABC311) on four occasions in 2008 and Total PCBs were detected at a maximum of ug/l. In their Outfall Basin 44A Source Investigation Report (March 2011), they concluded that the basin is not a significant source of PCBs to the Willamette River. Discharge is unlikely to occur in the present or future for two reasons. First, a perimeter berm surrounds the site, which was further improved in 2011 and Work included rehabilitating existing berm sections and installing new sections to make the gravel berm system continuous around the downgradient portion of the site property. A reinforced concrete roll-over ramp was

7 Page 7 of 8 constructed at the substation access gate off NE Russell Street and tied into the liner of the berm system. The current berm system is shown in Attachments 2 and 3. At present, rainwater falling on the site either infiltrates directly or drains to the on-site infiltration pond. Second, stormwater in the Outfall 44A basin, which includes catchbasins near the substation property, has been diverted to the interconnected tunnel system since late Overflow from the system is expected to occur, on average, 2.5 times per year, which could results in the release of stormwater from the site to the Willamette River if discharge from the substation occurred coincident with a combined sewer outfall (CSO) overflow event. Discharge would likely not occur at an outfall within Portland Harbor RM 11E, but instead a more downstream outfall such as OF-46 or -47. All of this information confirms the low potential for contaminant transport off site via stormwater or any subsequent impacts to the river. Given that the site is largely covered by crushed rock or gravel, wind erosion or off-site tracking of soil contaminants is unlikely to occur. Improvements to the NE Russell Street gate have further reduced the potential for track-off. Future Measures for Ongoing Stormwater Monitoring and Berm Maintenance As described in Section 4.4 of the Completion Report, PacifiCorp has implemented a number of best management practices (BMPs) to assure that good stormwater management practices continue into the future, including: Ongoing, as needed, placement of additional crushed rock to maintain the continuous rock cover throughout the Substation. Development of Soil Management Plans for onsite maintenance or construction activities that may include a disturbance of potentially erodible soils. Environmental awareness training for PacifiCorp Substation Operations personnel. The constructed stormwater source control improvements such as the berms and rollover ramp are maintained by PacifiCorp s Substation Operations through their Oil Spill Prevention, Control and Countermeasure Plan (SPCC Plan) for the Portland Area Substations. PacifiCorp personnel perform routine visual inspections pursuant to their SPCC Plan to assure that the source control features are maintained. As part of the SPCC plan, visual inspections pertaining to the SCMs are conducted a minimum of once per quarter and include the following: Lined berms All berm material must be covered with gravel/yard rock. Inspect for exposed or damaged liner material. Concrete curb and concrete ramp Inspect concrete for cracks or structural damage. Inspect for pathways through which drainage could exit the site. Infiltration basin Inspect pond for drainage and overflow, or oil drainage on pond surface. Inspect perimeters of pond for exposed or damaged liner material. Any deficiencies are reported and a repair order is initiated through PacifiCorp s enterprise maintenance management system.

8 Page 8 of 8 Periodic storm event visual monitoring will also be performed to assure that no runoff from the substation occurs. Summary of Source Control Decision Based on the information presented above, DEQ concludes that Knott Substation is not a current or reasonably likely future source of contamination to the Willamette River and that no additional source control measures are required. Information Sources Final Preliminary Assessment Report for the PacifiCorp Knott Substation. Bridgewater Group, Inc., October Knott Street Substation Dry Well Sampling and Closure Plan. CH2M HILL, November Underground Injection Control (UIC) Closure Report, UIC Number PCB Engineering + Environmental, October 3, Stormwater Source Control Measures Completion Report, Knott Substation. Bridgewater Group, Inc., November Outfall 44A Source Investigation Report. City of Portland Environmental Services, March Portland Harbor Joint Source Control Strategy. Oregon DEQ and EPA, September Guidance for Evaluating the Stormwater Pathway at Upland Sites. DEQ, January Attachments Attachment 1 Site Location Map Attachment 2 Site Features Map Attachment 3 Catch Basin Locations Attachment 4 On-Site Sampling Locations Attachment 5 On-Site Sampling Results Attachment 6 City of Portland Catch Basin Sampling Locations Attachment 7 Catch Basin Sampling Results