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1 GROUNDWATER INVESTIGATION: City of Medford Maintenance Center, Medford Oregon (ODEQ # ) Prepared for: Brice Perkins, P.E., City of Medford Prepared by: Robert Coffan, Principal Hydrologist and Charles Lane, R.G. Katalyst Associate K ATALYST, INC. adding value to our natural resources facilitating community change Date: January 29, 2015 (541) * rcoffan@gmail.com

2 GROUNDWATER INVESTIGATION: City of Medford Maintenance Center, Medford Oregon (ODEQ # ) Prepared for: Brice Perkins, P.E. Deputy Public Works Director - Operations City of Medford 821 N Columbus Ave Medford, OR Prepared by: Robert Coffan, Principal Hydrologist 2499 Happy Valley Dr. Medford, OR and Charles Lane, R.G. Katalyst Associate Date: January 29, 2015 Report Page 2 of 4

3 Table of Contents Executive Summary INTRODUCTION BACKGROUND Site Use Physical Setting Topography Soil and Geology Surface Water Groundwater Prior Remediation ODEQ Communications WORK PLAN FIELD WORK Initial Site Visit Field Sampling Borehole Advancement Survey and Wrap-Up RESULTS Comparative Risk-Based Screening Standards Applicable Soil Standards Applicable Water Standards Soil Groundwater Occurrence Quality CONCLUSIONS RECOMMENDATIONS LIMITATIONS References Report Page 3 of 4

4 Tables Table 1. Soil Sampling Results Table 2. Groundwater Sampling Results Figures Figure 1. Site Location Figure 2. Relevant Present Day Features Figure Soil Sampling Locations: Main Excavation (above) and Along Fuel Distribution Line (below) Figure 4. Groundwater Sampling Locations Photographs Cover Photograph. Looking northwest as the GeoProbe is setting up to advance borehole TWP Inset: Collecting a groundwater sample at TWP Photograph 1. Field work began with review of the Work Plan, buried utility walk, and health & safety briefing Photograph 2. Borehole advancement and sampling equipment was steam cleaned prior to use at each borehole Photograph 3. Water purging and sampling in progress at TWP Photograph 4. This core illustrates a saturated sandy stringer at about 16 feet bgs (top) underlain by dry crumbly, oxidized silt (below) down to the total depth of 20 feet bgs at TWP Photograph 5. A soil sample at the interface with the saturated gravel stringer at about 11 feet bgs was collected. Core top to bottom goes from upper left to lower right Appendices Appendix A. Appendix B. Appendix C. Appendix D. ODEQ Letters and Background Summary from the 1997 Remediation Work Plan Borehole Logs and Water Purging Logs Laboratory Results Report Page 4 of 4

5 Executive Summary In 1997, petroleum-contaminated soil was remediated by excavation from a former underground storage tank complex located at the Medford Service Center (MSC). Soil and groundwater samples were collected to characterize the contaminants at that time, and the Oregon Department of Environmental Quality (ODEQ) assigned a leaking underground storage tank (LUST) # of to the Site. Soil samples were collected to confirm the final conditions of soil left in place at the Site. Though water samples collected from the excavation pit were analyzed, no post remediation groundwater samples were collected to confirm remaining groundwater conditions. Recently, the ODEQ reviewed the former file, and sent a letter to the MSC stating that the LUST file is still open, and investigation of the extent of possible groundwater impacts was needed. The City of Medford (City) subsequently retained (Katalyst) to assist. This report provides the results of a groundwater investigation performed at the Site with input from ODEQ as part of the process. This work was performed under the direct supervision of a geologist registered in the state of Oregon. The reports from the previous 1997 investigation were reviewed, along with a discussion with ODEQ staff regarding outstanding issues and concerns. A Work Plan was prepared and approved. Field work was performed from through Five boreholes were advanced and groundwater was collected through the use of temporary well points (TWPs). Soil samples were also collected. Results were compared to generic riskbased standards applicable to the Site. Conclusions The compounds of concern identified in the 1997 report generating the LUST file pertain to gasoline and/or diesel-related fuel, from the former UST complex. Groundwater was characterized from water flowing back into the open pit, serving as a worst case scenario of initial concentrations. Benzene appeared to be the principal contaminant of concern at that time, with concentrations ranging from non-detect 1 to 73.2 micrograms per liter (µg/l). However benzene dropped four-fold to 16 µg/l after a second purge of the excavation pit three weeks later. All water purged from the pit during the 1997 process appears to have been successfully treated at the time. No signs of contamination (staining, odors, etc.) were observed in the soil or water during this investigation. No gasoline or diesel fuel-related compounds were detected in any soil or groundwater sample collected during this investigation. This indicates that subsurface issues associated with the prior LUST have been successfully remediated. Low concentrations of TPH-Oil were detected in two soil samples; however those concentrations are well below all generic risk-based cleanup standards. Low concentrations of TPH-Oil were detected in every groundwater sample. However none of the concentrations exceed the most stringent generic risk-based standard applicable to the Site given the current use and projected use into the foreseeable future. In addition, no specific compounds typically related to TPH-Oil (such as poly-cyclic 1 In this report, not detected means that the compound was not detected above the laboratory s method reporting limit for that compound.

6 aromatic hydrocarbons) were detected in the water sample exhibiting the highest concentration of TPH-Oil. The source of the low concentrations of oil-related hydrocarbons in the shallow perched groundwater is likely due to vehicle and equipment maintenance and use at the MSC. Of the 64 VOCs analyzed, a trace concentration of one solvent, PCE at 2.55 µg/l, was detected in one groundwater sample from TWP4. This concentration is well below ALL generic risk-based standards. Groundwater appears to be perched in intermittent, isolated stringers of permeable sand and gravel lenses at the Site; one borehole (TWP1) was dry whereas a borehole less than 60 feet away (TWP2) contained thin saturated lenses of sand and gravel, immediately providing groundwater at one foot below ground surface. Other boreholes remained dry for several hours, taking a day or more to collect water. This locally perched groundwater is likely not representative of regional groundwater conditions. Groundwater flow is most likely to the northeast. Recommendations Based on the investigation, the former LUST site has been successfully remediated and groundwater conditions have been adequately characterized. No further action is necessary. Katalyst recommends that the LUST Site be closed and that the ODEQ provide a letter of No Further Action status. Report Page 2 of 14

7 1.0 INTRODUCTION In 1997, petroleum-contaminated soil (PCS) was remediated by excavation from a former underground storage tank (UST) complex located at the Medford Service Center (MSC) (Site) (Figure 1). Soil and groundwater samples were collected to characterize the contaminants at that time, and the Oregon Department of Environmental Quality (ODEQ) assigned a leaking underground storage tank (LUST) # of to the Site. PCS was treated onsite and disposed of off-site. Soil samples were collected to confirm the final conditions of soil left in place at the Site. Groundwater was encountered in the excavated area, requiring onsite treatment (Agate 1997). Samples of water collected from the excavation pit were analyzed, however there are no records of any post remediation groundwater sampling to confirm remaining groundwater conditions. In 1999, the ODEQ wrote a letter to the MSC stating that additional groundwater investigation was needed in order to close the Site. However, the words No Further Action were listed in the subject line of the letter. Perhaps this was meant to reference that the soil aspects had been completed. In any event, the case was inadvertently closed in ODEQ files, and the investigation stopped. Recently in September 2015, the ODEQ reviewed the former file, and subsequently sent a letter to the MSC stating that the LUST file is still open, and that, Long-term risks to human health or the environment at your property are possible and need to be investigated ; more specifically, investigate the extent of possible groundwater impacts (ODEQ 2015). The City of Medford (City) subsequently retained (Katalyst) to assist in determining next steps to take. Katalyst, in turn, re-contacted ODEQ to gain a better understanding of the current issues and concerns. This report provides the results of a groundwater investigation performed at the Site with input from ODEQ as part of the process. This work was performed under the direct supervision of a geologist registered in the state of Oregon. 2.0 BACKGROUND The Medford Service Center is comprised of Tax Lots 2500 (11.67 acres) and 400 (10.88 acres) in Township 37S, Range 2W, Section 4cb in Jackson County. Report Page 3 of 14

8 2.1. Site Use The Site is the location of the vehicle and equipment Service Center for the City of Medford and has been for more than 40 years. The Site is covered predominantly with asphalt, service buildings, equipment storage structures and other impermeable surfaces (Figure 2). The Site is zoned as Light Industrial, and according to the Jackson County Tax Assessor, all of the tax lots adjacent to the Site are zoned as either Light Industrial or General Industrial. There is a small landscaped area southeast of the Office. There is also an open area and a settling pond for city equipment cleanout to southwest. The area where the former UST complex was located relative to the rest of the present-day structures at the MSC is shown in Figure 2. Building J has been constructed over the remediated area. The present-day fueling area and UST pad are located to the east near Building C, approximately 500 feet east of the former UST Complex. There are no plans for changes in land use or ownership in the foreseeable future Physical Setting Topography Regionally, the area slopes gently to the northeast towards Bear Creek, which is located about 1 mile to the northeast. Locally, the Site is located at approximately 1340 feet above sea level. It is relatively flat, and has been graded and sloped with fill to suit vehicle traffic, stormwater runoff, building construction, and other development practices over the years Soil and Geology According to the US Department of Agriculture s Natural Resource Conservation Service (NRCS), the natural soil type at the Site is listed as the Agate loam, which is in Hydrologic Group: Class D - Very slow infiltration rates. Soils are clayey, have a high water table, with a low-permeability layer commonly found at shallow depths. However the Site surface has been significantly altered by past grading and fill placement. Based on the geologic map of Oregon by Walker and MacLeod, the Site resides on quaternary alluvium (river-deposited sediments) comprised of alternating and discontinuous layers and lenses of clays, silts, sand lenses and gravels and cobbles Surface Water The Site is located in the Bear Creek subwatershed of the Rogue Watershed. There are no permanent surface water features on the Site. There is an ephemerally wet Report Page 4 of 14

9 drainage area northeast of the Site. The nearest perennial surface water feature is Bear Creek about 600 feet to the east-northeast. However the cleanout settling pond in the southwest portion of the Site periodically contains water Groundwater In the greater site area groundwater flows from the southwest to the northeast towards Bear Creek. Onsite however, shallow groundwater flow may respond to anthropogenic features, such as runoff ditches, the cleanout area, irrigated areas and fill placement. It is Katalyst s experience that shallow groundwater in this portion of Medford is found perched (at varying levels) in the alluvially-deposited thin, intermittent lenses of more permeable coarse sand between layers of less permeable clay and silt. Onsite, water-charged perched stringers are found at depths as shallow as 5 feet below ground surface (bgs) to nearly 30 feet bgs (presented in Section 4). There are no wells on the Site Prior Remediation Decommissioning and remediation of the former UST complex was performed in 1996 through 1997 under the direction of Agate Engineering (Agate 1997). A figure from the 1997 report depicting the location of the former UST Complex, excavation extents, and soil sampling locations, is shown in Figure 3. The 1997 letter report summarizing site conditions, identifying the potential contaminants of concern, delineating the extents of excavation, and providing confirmation soil sampling results is part of the ODEQ record. Therefore extensive details are not reiterated in this report, and the reader is referred to the 1997 report, a copy of which is included in Appendix A. Soil and groundwater samples were collected to characterize the contaminants. PCS associated with diesel and/or gasoline-related fuel was excavated, treated onsite, ultimately approved as successfully treated, and disposed of off-site. Groundwater was encountered in the excavated area, requiring onsite treatment using a baker tank (large holding tank). Soil samples were also collected to confirm the final conditions of soil left in place at the Site. Several groundwater samples were collected to characterize groundwater during remediation. Four samples were collected of groundwater flowing back into the excavation pit after purging, and analyzed for benzene, toluene, ethylbenzene, and xylenes (commonly referred to as BTEX), total petroleum hydrocarbons (TPH ), and dissolved lead. Low concentrations of BTEX and TPH were detected in at least one of the water samples. Lead was not detected in any groundwater sample. Benzene appeared to be the principal contaminant of concern at that time, Report Page 5 of 14

10 with concentrations ranging from non-detect 2 to 73.2 micrograms per liter (µg/l); dropping to 16 µg/l after a second purge of the excavation pit three weeks later. However there are no records of any groundwater sampling to confirm remaining post remediation groundwater conditions ODEQ Communications As mentioned above, ODEQ wrote a letter to the MSC 18 years ago stating that additional groundwater investigation was needed in order to close the Site. In December 2015, Katalyst contacted Eric Clough, the Western Region Natural Resource Specialist in the Tanks Program to discuss the situation and determine what still needed to be done given the time gone by. Copies of the 1999 and 2015 ODEQ letters are included in Appendix A. 3.0 WORK PLAN The information introduced above was used to prepare a Work Plan outlining the methodology to perform the groundwater characterization work at the Site. The Work Plan included the following sections: Basic Approach and Objectives, Field Work, Sampling and Analysis Plan, Health and Safety Plan, Investigation-Derived Waste Plan, Assumptions, Reporting, and Schedule. A draft Work Plan was submitted to ODEQ for review, and was approved with edits on November 15, The final Work Plan is included in Appendix B. The following rationale was developed and agreed upon: No additional soil reconnaissance is warranted, and field work will be limited to groundwater assessment pertaining to the area. The area encompassing the remote distribution line and south dispenser has been characterized and is not included as part of this investigation (Figure 3). Additional groundwater investigation is limited to the formerly excavated area. Though it is highly unlikely that the stockpiled area poses any risk, it was in 2 In this report, not detected means that the compound was not detected above the laboratory s method reporting limit for that compound. Report Page 6 of 14

11 the general vicinity of the excavation extents and one borehole was advanced in this former area. Five boreholes were advanced as shown in Figure 4, and groundwater was collected using temporary well points (TWPs) if encountered. The TWPs were surveyed to a common datum to determine groundwater elevations. One soil sample was collected in each TWP. Laboratory Analyses consisted of o Total petroleum hydrocarbons in the gasoline range (TPH-G), o Total petroleum hydrocarbons in the diesel range (TPH-Dx), and o A suite of 64 Volatile Organic Compounds (RBDM VOCs). 4.0 FIELD WORK 4.1. Initial Site Visit Katalyst visited the Site on to mark locations for the TWPs and meet with MSC staff Marc Bokish to learn about any private utility lines that may be in the area. A public utility locate was called in the same day Field Sampling Field activities began on Work began with a Health and Safety Tailgate Meeting with Katalyst Staff and the GeoProbe crew from Cascade Drilling (Photograph 1). The Work Plan was discussed, and the work crew walked the site to inspect each TWP location and marked out utilities Borehole Advancement TWP5 Borehole advancement began on the upslope/upgradient location, TWP5. The lithology was a combination of alternating clays, sandy clays, and silts, with thin stringers of sand and gravel. The borehole was predominately dry throughout, though moist material was encountered at about 26 feet bgs, becoming dry again below that depth to refusal at a total depth of 30 feet bgs. The borehole remained dry for the entire day, but it was left open to see if any water developed overnight. No staining, odors, or other signs of potential hydrocarbon contamination was observed in the continuous cores. A soil sample (TWP5-26.0) was collected from the moist area. Borehole logs for each of the five boreholes are included in Appendix C. Report Page 7 of 14

12 It turned out that a small amount of water developed in borehole TWP5 overnight, and it was sampled the following day. The static water level (SWL) was measured at feet bgs. The borehole went dry after purging 5.5 liters of water. Field parameters ph, electro-conductivity, and temperature were monitored during purging to help verify that water was representative of surrounding aquifer conditions. The borehole was allowed to refill, and a water sample (TWP5) was collected after 7 liters were purged. No odors or discoloration associated with hydrocarbons were observed during purging. Water purge logs for each of the boreholes are included in Appendix C. Disposable tubing was used to sample water from each borehole. All other sampling equipment was decontaminated per the Work Plan prior to beginning work at another location (Photograph 2). TWP4 The lithology of borehole TWP4 was a combination of alternating clays, sandy clays, and silts, with thin stringers of sand and gravel. The borehole was predominantly dry throughout, though moist material was encountered at about 25 feet bgs, becoming dry again below that depth to refusal at a total depth of 30 feet bgs. The borehole remained dry for the entire day, but it was left open to see if any water developed overnight. No staining, odors, or other signs of potential hydrocarbon contamination was observed in the continuous cores. A soil sample (TWP4-25.0) was collected from the moist area. It turned out that a small amount of water developed in borehole TWP4 overnight, and it was sampled the following day. The SWL was measured at feet bgs. The borehole went dry after purging just 1 liter of water, and a small amount of water was collected after 1.5 liters were purged (Photograph 3). No odors or discoloration associated with hydrocarbons were observed during purging. TWP3 The lithology of borehole TWP3 was a combination of alternating clays, sandy clays, and silts. A moist area was observed in a silty clay from 10 to 11.5 feet bgs, and a soil sample (TWP3-11.0) was collected from this location. One stringer of saturated silty sand was observed from 15.5 to 17 feet bgs. The lithology became fairly dry below this depth down to the total depth of 20 feet bgs. The saturated stringer, and the obvious dry lithology underlying it, are shown in Photograph 4. No staining, odors, or other signs of potential hydrocarbon contamination were observed in the continuous cores. The SWL at TWP3 was measured at 11.5 feet bgs after waiting 4 hours. TWP3 was also a low-producing well point, going dry after purging 1 liter of water. No odors or discoloration associated with hydrocarbons were observed during purging. Report Page 8 of 14

13 TWP2 The lithology of borehole TWP2 was a combination of alternating clays, sandy clays, and silts, with thin stringers of sands and gravels. A saturated sand layer, grading to gravel was encountered from 5 to 6 feet bgs. A second saturated gravel stringer was encountered from 10.5 to 12 feet bgs and a soil sample (TWP2-10.5) was collected at this interface (Photograph 5). No staining, odors, or other signs of potential hydrocarbon contamination was observed in the continuous cores. The SWL at TWP2 quickly rebounded and was measured at 1 foot bgs. A duplicate water sample (TWP2 and TWP6) was collected at this location. No odors or discoloration associated with hydrocarbons were observed during purging. TWP1 The lithology of borehole TWP1 was a combination of alternating clays, sandy clays, and silts. A slightly moist area was observed in a silty sand from 11.5 to 13 feet bgs, and a soil sample (TWP1-12.5) was collected from this location. The lithology became fairly dry below this depth down to the total depth of 20 feet bgs. No staining, odors, or other signs of potential hydrocarbon contamination was observed in the continuous cores. No water was encountered or developed over time in TWP Survey and Wrap-Up The five boreholes were surveyed to a common datum prior to leaving the Site. All of the boreholes were properly filled with bentonite chips and plugged at the surface with asphalt cold-patch. Borehole cuttings and purge water were stored in two 55- gallon drums that were sealed, labeled, and stored on-site pending results from laboratory analysis. Field work was completed on Soil and water samples were transported by hand to Nielson Research Corporation on using standard Chain of Custody Protocol per the Work Plan. 5.0 RESULTS Soil and groundwater sampling results are shown in Table 1 and Table 2, respectively. Complete copies of laboratory results and quality control measures are included in Appendix D. If a compound was not detected in any soil or groundwater sample, it is not shown in either table. For example, none of the gasoline-related compounds: benzene, toluene, ethylbenzene, and xylenes (commonly referred to as BTEX) were detected in any sample, and are therefore not listed in the tables. Report Page 9 of 14

14 Comparative standards are also shown in tables 1 and 2. Selection of the appropriate standards is discussed below Comparative Risk-Based Screening Standards The potential compounds of concern were identified in the 1997 report and the subsequent ODEQ LUST file. Based on that, comparative screening standards were selected using the ODEQ Risk-Based Decision Making for the Remediation of Petroleum-Contaminated Sites (ODEQ 2012) Applicable Soil Standards Each of the soil-related exposure pathways and associated risk-based standards were considered, given the current land use, as well as projected land use into the foreseeable future. The Site is owned by the City, has been used as a Service Center for more than 40 years, and is projected for the same use into the foreseeable future. The Site is zoned as Light Industrial, and every tax lot surrounding the Site is also zoned as either Light Industrial or General Industrial. Therefore the soil exposure routes pertaining to residential or urban residential use are not applicable. The soil exposure route leaching to groundwater was also considered. However, shallow groundwater is not used as a drinking water source in downtown Medford. In addition, there is no existing well at the Site. Therefore leaching to groundwater as a drinking water source is also not an applicable exposure route. The following four exposure routes were considered as applicable to the Site: Vapor intrusion into buildings-occupational, Volatilization to outdoor air-occupational, Soil ingestion/dermal contact-construction worker, and Soil ingestion/dermal contact-excavation worker. Of these pathways, the most stringent standards for the compounds detected in soil samples at the Site are for the soil ingestion/dermal contact-excavation worker scenario, which are therefore shown at the bottom of Table Applicable Water Standards Each of the water-related exposure pathways and associated risk-based standards were considered, given the current land use, as well as projected land use into the foreseeable future. Again, the Site has been used as a Service Center for more than 40 years, and is projected for the same use into the foreseeable future. The Report Page 10 of 14

15 Site and surrounding properties are zoned as Industrial. Therefore exposure routes pertaining to residential or urban residential use are not applicable. As mentioned in Section above, shallow groundwater is not used for drinking water in the City and there are no wells at the Site. In addition, the water sample collected to initially characterize groundwater during the excavation back in 1996 was collected directly from the excavation pit as the water was allowed to dewater further down the trench. Therefore, the results are conservative, or worst case, representing water in direct contact with the contamination in the trench, more than representing groundwater in the shallow aquifer at that time. Therefore groundwater ingestion from tapwater is not an applicable exposure route. However the potential exists to encounter groundwater during excavation in the future. Therefore the following exposure routes were considered as applicable to the Site: Encountering groundwater in an excavation, Vapor intrusion into buildings, and Groundwater volatilization into outdoor air. Of these, the most stringent standard for the compounds detected at the Site is groundwater in an excavation, which is shown at the bottom of Table Soil TPH-Gx and TPH-Dx were not detected in any soil sample (Table 1). TPH-Oil was detected in at low concentrations in two soil samples; TWP (570 mg/kg) and TWP (373). These concentrations are below ALL ODEQ risk-based standards and are well below (ten times lower) than generic risk-based standards applicable to the Site. No VOCs were detected in any soil sample Groundwater Occurrence Examination of boring logs for TWP5 and TWP4, as well as the hydrologic behavior of groundwater (how water flowed into the TWP during advancement and purging) in both well points indicates continuity of the water-bearing zone (at approximately 25 bgs) between them. Examination of the boring logs for TWP3 and TWP2, as well as the hydrologic behavior of groundwater in each of them, indicate that the waterbearing stringers in TWP3 and TWP2 are independent of each other, and each independent of the stringer found at greater depth in TWP5 and TWP4. Report Page 11 of 14

16 The measured static water levels are also shown in Table 2. However as mentioned above, the water levels are discontinuous and do not appear to relate to one another. For example, compare the water level of one foot bgs at TWP 2 to no water encountered 60 feet away at TWP1 (Figure 4). These different perched stringers do not allow a rigorous 3-point solution for the determination of groundwater flow direction. Examination of appropriate topographic maps, general direction of nearest downslope approach to Bear Creek, and rigorous solution of groundwater surface flow directions from other nearby areas/projects lead us to conclude that the most likely groundwater flow direction in this area is to the northeast Quality TPH-Gx and TPH-Dx were not detected in any water sample (Table 2). TPH-Oil was detected in every water sample, ranging from a low of 410 micrograms per liter (µg/l) at TWP2 to a high of 4270 µg/l at TWP5. These concentrations are well below the most stringent generic risk based standard for TPH-Oil applicable to the Site, which is listed as >S, meaning that the acceptable concentration is so high, it exceeds the solubility limit of TPH-Oil in water. No VOCs typically associated with fuels was detected in any of the groundwater samples. However, a trace amount (2.55 µg/l) of the solvent, tetrachloroethylene (PCE) was detected at TWP4. This concentration is well below ALL generic riskbased standards. Because TPH-Oil was detected in the groundwater, the groundwater sample exhibiting the highest concentration of TPH-Oil (TWP5 at 4210 µg/l) was also analyzed for PAHs. No PAHs were detected in the sample. 6.0 CONCLUSIONS The compounds of concern identified in the 1997 report generating the LUST file pertain to gasoline and/or diesel-related fuel, from the former UST complex. Groundwater was characterized from water flowing back into the open pit, serving as a worst case scenario of initial concentrations. Low concentrations of BTEX and TPH were detected in at least one of the water samples collected from the pit. Lead was not detected in any groundwater sample. Benzene appeared to be the principal contaminant of concern at that time, with concentrations ranging from non-detect 3 to 73.2 micrograms per liter (µg/l). However benzene dropped four-fold to 16 µg/l 3 In this report, not detected means that the compound was not detected above the laboratory s method reporting limit for that compound. Report Page 12 of 14

17 after a second purge of the excavation pit three weeks later. All water purged from the pit during the process appears to have been successfully treated at the time. No signs of contamination (staining, odors, etc.) were observed in the soil or water during this investigation. No gasoline or diesel fuel-related compounds (including BTEX) were detected in any soil or groundwater sample collected during this investigation. This indicates that subsurface issues associated with the prior LUST have been successfully remediated. Low concentrations of TPH-Oil were detected in two soil samples; however those concentrations are well below all generic risk-based cleanup standards. Low concentrations of TPH-Oil were detected in every groundwater sample. However none of the concentrations exceed the most stringent generic risk-based standard applicable to the Site given the current use and projected use into the foreseeable future. In addition, no specific compounds typically related to TPH-Oil (such as PAHs) were detected in the water sample exhibiting the highest concentration of TPH-Oil. The source of the low concentrations of oil-related hydrocarbons in the shallow perched groundwater is likely vehicle and equipment use at the MSC. Of the 64 VOCs analyzed, a trace concentration of one solvent, PCE at 2.55 µg/l, was detected in one groundwater sample from TWP4. This concentration is well below all generic risk-based standards. Groundwater appears to be perched in intermittent, isolated stringers of permeable sand and gravel lenses at the Site; one borehole (TWP1) was dry whereas a borehole less than 60 feet away (TWP2) contained thin saturated lenses of sand and gravel. Other boreholes remained dry for several hours, taking a day or more to collect water. This locally perched groundwater is likely not representative of regional groundwater conditions. Groundwater flow is most likely to the northeast. 7.0 RECOMMENDATIONS Based on the investigation, the LUST site has been successfully remediated and groundwater conditions have been adequately characterized. No further action is necessary. Katalyst recommends that the LUST Site be closed and that the ODEQ provide a letter of No Further Action status. 8.0 LIMITATIONS The conclusions presented in this report are professional opinions based on data described in this report. They are intended only for the purpose, Site location, and project indicated, and are based on the assumption that Site conditions do not Report Page 13 of 14

18 deteriorate from those observed during the investigation. This report is not a definitive study of contamination at the Site and should not be interpreted as such. This report was prepared for the City by Katalyst pursuant to a request for services by the City, and is accurate to the best of Katalyst s knowledge and belief. This report is based, in part, on unverified information supplied to Katalyst by third-party sources. While efforts have been made to substantiate this third-party information, Katalyst cannot be responsible for the integrity of the information provided in the third-party documents. Katalyst staff who assisted with this investigation and report are engineers and scientists, not attorneys. Therefore, it must be clear to all parties that this report does not offer any legal opinion, representation, or interpretation of environmental laws, rules, regulations, or policies of federal, state, or local government agencies. References Agate Letter Report Summarizing Environmental Assessment and Remediation Work Performed at the Former UST Complex and Fuel Distribution Facilities at the City of Medford Service Center, 821 N Columbus Ave, Medford, OR, DEQ LUST File No Agate Engineering Inc. March 29, ODEQ No Further Action Letter, USTC # , City of Medford Service Center, 821 N Columbus Ave, Medford, Jackson County. Oregon Department of Environmental Quality. May 25, ODEQ Risk-Based Decision Making for the Remediation of Petroleum- Contaminated Sites. Oregon Department of Environmental Quality. September 2003 Revised June ODEQ Project Status, City of Medford Service Center, Medford OR DEQ file # Oregon Department of Environmental Quality. September 28, Report Page 14 of 14

19 Table 1. Soil Sampling Results (milligrams per kilogram) Total Hydrocarbons VOCs Depth ID Date (feet bgs) TPH-Gx TPH-Dx TPH-Oil Tetrachloro ethylene (PCE) MSC-TWP /2/ ND ND ND - MCS-TWP /2/ ND ND ND - MSC-TWP /2/ ND ND MSC-TWP /2/ ND ND 373 ND MSC-TWP /2/ ND ND ND - C o m p a r a t i v e S t a n d a r d s 1-Most Stringent-ALL Most Stringent-Applicable VOCs includes all 64 volatile organic compounds using EPA method 8260 TPH-G = total petroleum hydrocarbons in the gasoline range TPH-Dx = total petroleum hydrocarbons in the diesel range TPH-Oil = total petroleum hydrocarbons in the lube oil Depth = feet below ground surface ND = not detected above laboratory reporting limits - = not analyzed RED = the compound exceeds the most stringent applicable standard 1 = ODEQ pathway "Soil leaching to groundwater: residential setting" 2 = ODEQ Pathway "Encountered by an excavation worker" GW Investigation: MSC

20 Table 2. Groundwater Sampling Results (shown in micrograms per Liter) ID Sample Date Static Water Level (MSL) TPH-Gx TPH-Dx TPH-Oil VOCs Tetrachloro ethylene (PCE) MSC-TWP1 DRY MSC-TWP2 12/3/2015 ND ND 478 ND duplicate-twp2 12/3/2015 ND ND 410 ND - MSC-TWP3 12/3/ ND ND 2180 ND - MSC-TWP4 12/3/ ND ND MSC-TWP5 12/3/ ND ND 4270 ND ND Comparative Standards 1-Most Stringent-ALL na 2-Most Stringent Applicable 14,000 >S >S 5400 na All concentrations shown in micrograms per liter ND = not detected above laboratory reporting limits - = not analyzed BOLD = the compound exceeds the most stringent ODEQ standard for the compound RED = the compound exceeds the most stringent applicable standard >S = the concentration is greater than the saturation range for the compound 1 = ODEQ Pathway "Groundwater as drinking water: residential setting" 2 = ODEQ Pathway "Encountering groundwater in an excavation" MSL = Elevation above mean sea level TPH-G = total petroleum hydrocarbons in the gasoline range TPH-Dx = total petroleum hydrocarbons in the diesel range TPH-Oil = total petroleum hydrocarbons in the lube oil range VOCs = volatile organic compounds (64 total) PAHs = poly-aromatic hydrocarbons (16 total) >S = Concentration exceeds the solubility limit for the compound Total Petroleum Hydrocarbons PAHs GW Investigation: MSC

21 Source: 2015 oblique aerial modified from Google Earth Figure 1. Site Location K atalyst, Inc. GW Investigation MSC (# )

22 Tax Lot 2300 J Former Temporarily Stockpiled PCS in 1997 AREA OF FOCUS Former UST Complex and Remediation in 1997 Tax Lot 2500 (11.67 acres) F C Current UST Pad & Fueling Area B D E G Medford Service Center Equipment Clean-Out Area I Offices A-1 A-2 Landscaped Area Tax Lot 400 (10.88 acres) Source: Modified from Google Earth Approximate Scale (in feet) Figure 2. Relevant Present-Day Features K atalyst, Inc. GW Investigation MSC (# )

23 1999 Excavation Extents (Building J not yet constructed) D G Remote (South) Fuel Lines E A-1 Remote (South) Dispenser Island Source: Modified from 1999 Report by Agate Engineering Figure Soil Sampling Locations: Main Excavation (above) and Along Fuel Distribution Line (below) K atalyst, Inc. GW Investigation MSC (# )

24 TWP TWP TWP Bldg J TWP1 dry B TWP ~ LEGEND ~ Approx. Inferred GW Flow Direction (not from local discontinuous water levels) Former 1997 Excavation Extent Former Fuel Lines D Formerly Staged Soil TWP Temporary Well Point Location Discontinuous Static Water Level (msl) Source: Google Earth Aerial Photograph Approximate Scale (in feet) Figure 4. Groundwater Sampling Locations K atalyst, Inc. GW Investigation MSC (# )

25 Photograph 1. Field work began with review of the Work Plan, buried utility walk, and health & safety briefing Photograph 2. Borehole advancement and sampling equipment was steam cleaned prior to use at each borehole Photos Medford Service Center Page 1 of 3 Groundwater Investigation

26 Photograph 3. Water purging and sampling in progress at TWP Photograph 4. This core illustrates a saturated sandy stringer at about 16 feet bgs (top) underlain by dry crumbly, oxidized silt (below) down to the total depth of 20 feet bgs at TWP Photos Medford Service Center Page 2 of 3 Groundwater Investigation

27 Photograph 5. A soil sample at the interface with the saturated gravel stringer at about 11 feet bgs was collected. Core top to bottom goes from upper left to lower right Photos Medford Service Center Page 3 of 3 Groundwater Investigation