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Home My WebLink About024-23051 Prop Development Phase II Report Final & A S S O C I A T E S , I N C. GEOTECHNICAL ENGINEERING  ENVIRONMENTAL ENGINEERING CONSTRUCTION TESTING & INSPECTION 2205 Coy Avenue • Bakersfield, California 93307 • Ph: (661) 837-9200 • With Offices Serving the Western United States 024-23051 Prop Development Phase II Report Final.docx August 10, 2023 Project No. 024-23051 Mr. Matthew Wade Urban Land Advisors, LLC P.O. Box 11385 Bakersfield, California 93389 mwade@landstonecompanies.com RE: Phase II Limited Soil and Soil Vapor Assessment/Vapor Intrusion Risk Evaluation Northeast Corner of Panama Lane and Buena Vista Road APN 544-030-04 (17.54 Acres) Bakersfield, California Dear Mr. Wade: Pursuant to your request, Krazan & Associates, Inc. (Krazan) has conducted a Phase II Limited Soil and Soil Vapor Assessment and a Vapor Intrusion Risk Evaluation (VIRE) at the referenced property (subject site). This work was based on the findings provided in Krazan’s June 9, 2023 Phase I Environmental Site Assessment (ESA) Project No. 024-23051 prepared for Urban Land Advisors, LLC. The findings of the Phase I ESA are summarized below and the results of the Phase II Limited Soil and Soil Vapor Assessment and Vapor Intrusion Risk Evaluation are presented following background information. BACKGROUND During Krazan’s June 2023 Phase I ESA, Krazan identified evidence of recognized environmental conditions (RECs) and/or a historical REC (HREC) in conjunction with the subject site as defined by ASTM E 1527-21. Based on review of regulatory documents, the subject site was impacted with a release of crude oil from a pipeline adjacent to the west of the subject site. To date, the City of Bakersfield Fire Department (CBFD) has not found a closure letter addressing this release that was investigated by CBFD during 2000. Therefore, Krazan recommended the release of crude oil from the pipeline be further investigated. Additionally, Krazan recommended a Soil Vapor Survey (SVS) be conducted within the western portion of the subject site to evaluate the potential for vapor intrusion into proposed future buildings. PURPOSE OF THE PHASE II LIMITED SOIL AND SOIL VAPOR INVESTIGATION AND VAPOR INTRUSION RISK EVALUATION The purpose of the Phase II Limited Soil and Soil Vapor Investigation was to assess constituents of potential concern (COPCs) in soil and soil vapor to determine potential risk to human health and the environment. The COPCs for this investigation included: Total extractable petroleum hydrocarbons (TEPH) and the volatile organic compounds (VOCs) benzene, toluene, ethylbenzene and total xylenes (BTEX) in soil and analysis of VOCs in soil vapor. Proposed Residential Property Project No. 024-23051 Bakersfield, California Page No. 2 of 6 KRAZAN & ASSOCIATES, INC. With Offices Serving the Western United States 024-23051 Prop Development Phase II Report Final.docx The purpose of the VIRE was to assess whether concentrations of benzene detected in soil vapor during the soil vapor investigation are within levels considered acceptable to the California health and environmental protection agencies. Applicable Regulatory Agency References The results of the soil sampling and SVS were evaluated using Environmental Screening Levels (ESLs) established in November 2007 (Revised January 2019 with a second Revision in July 2019) by the San Francisco Regional Water Quality Control Board’s (SFRWQCB) referenced in the technical document titled, Screening for Environmental Concerns at Sites With Contaminated Soil and Groundwater. According to the SFRWQCB’s 2007 document, ESLs are considered to be conservative. Under most circumstances and within limits described by the SFRWQCB, the presence of a chemical in soil, soil-vapor or groundwater at concentrations below the corresponding ESL (Residential Exposure or Commercial/Industrial Exposure) for the respective constituent can be assumed not to pose a significant, long-term (chronic) threat to human health and the environment. Additional evaluation will generally be necessary at sites where a chemical is present at concentrations above the corresponding ESL. SCOPE OF WORK Krazan prepared and implemented a site-specific health and safety plan (HASP) prior to field work. Krazan’s Standard Operating Procedures (SOPs) were implemented for sample collection, sample equipment decontamination, sample storage, transport, hold times, and chain-of-custody documentation in the field. The following summarizes the investigation methodology and presents the results of the chemical analysis of the soil and SVS and the results of the VIRE. In addition to presenting our findings, this report also includes our conclusions and recommendations, based on the results of the investigation. The contaminants encountered are identified and include a comparison of the contaminant levels to ESLs for soil and soil vapor. The laboratory analytical reports, and other supporting documentation are appended to this report. PHASE II LIMITED SOIL AND SOIL VAPOR ASSESSMENT AND VAPOR INTRUSION RISK EVALUATION Krazan has conducted a Phase II Limited Soil and Soil Vapor Assessment and a VIRE at the subject site. The findings are presented below: LIMITED SOIL ASSESSMENT Krazan conducted the limited soil assessment (LSA) at the subject site on June 22, 2023 which included advancing four soil borings (SB-1, SB-2, SB-3 and SB-4) to depths of 30 feet below ground surface (bgs) along the western side of the subject site, see Figure 1. The soil borings were located approximately 25 feet to the east of the concrete curb along Buena Vista Road, and at 60-foot intervals north of Panama Lane. Soil samples collected at 20, 25 and 30 feet bgs were analyzed for BTEX and TEPH from all four borings. Additionally, all samples were field screened with a photo-ionization detector (PID) at five-foot intervals from the surface to 30 feet bgs. Twelve (12) of the 24 soil samples collected were submitted for analysis of the COPCs. The discrete soil samples submitted for analysis were properly sealed and labeled with specific sampling and project information and retained within a chilled container to 4 degrees Celsius. Sampling information was entered on a chain-of-custody form and the samples were shipped under chain-of custody to a State Certified Laboratory for analysis of COPCs to include: TEPH carbon chain analysis (TEPH-cc) by EPA Method 8015B; and BTEX by EPA Method 8260B. Proposed Residential Property Project No. 024-23051 Bakersfield, California Page No. 3 of 6 KRAZAN & ASSOCIATES, INC. With Offices Serving the Western United States 024-23051 Prop Development Phase II Report Final.docx LIMITED SOIL ASSESSMENT FINDINGS The following summarizes the results of the limited soil assessment. Laboratory results are included in Table I. The complete SunStar laboratory analytical report is included in Attachment A. Soil Borings SB-1 thru SB-4 Soil Borings SB-1 thru SB-4 were all advanced to a total depth of 30 feet bgs. In general, all four soil borings encountered a loam at the surface; a light grey silty sand, loose, dry with no staining and on odors from 5 to 15 feet bgs; a light brown silty sand, slightly clayey, loose, moist with no staining and no odors at 20 feet bgs; a grey silty sand, loose, dry with no staining and no odors at 25 feet bgs; and a grey sand, fine-grained, loose, dry with no staining and no odors at 30 feet bgs. In general, no stained soil was encountered and the PID did not detect VOCs above 5 parts per million (ppm). Soil Sample Analytical Results Soil samples with detectable TEPH were reported only in the diesel (DRO) and motor oil (MORO) hydrocarbon ranges. BTEX was not detected at or above the laboratory’s reporting limits (RLs). In summary, no BTEX concentrations were reported and TEPH concentrations were reported below 100 milligrams per kilogram (mg/kg), which is below regulatory action levels. The following summarizes the soil sample analysis results. SB-1 TEPH was not detected at or above the laboratory’s RLs for samples collected at 20 and 25 feet bgs. MORO was detected in sample SB1-30’ at 18 mg/kg. SB-2 DRO was detected in sample SB-2-20’ at 43 mg/kg, sample SB-2-25’ at 44 mg/kg and sample SB2-30’ at 42 mg/kg. MORO was detected in sample SB2-25 at 29 mg/kg and sample SB-2-30’ at 22 mg/kg. SB-3 TEPH was not detected at or above the laboratory’s RLs for samples collected at 25 feet bgs. DRO was detected in sample SB-3-20’ at 46 mg/kg and sample SB3-30’ at 42 mg/kg. MORO was detected in sample SB3-20 at 19 mg/kg and sample SB-3-30’ at 18 mg/kg. SB-4 DRO was detected in sample SB-4-20’ at 43 mg/kg, sample SB-4-25’ at 40 mg/kg and sample SB4-30’ at 38 mg/kg. MORO was detected in sample SB4-25 at 16 mg/kg and sample SB-4-30’ at 25 mg/kg. SOIL VAPOR SURVEY Krazan conducted a SVS on July 6, 2023 using Optimal Technology (Optimal), a State-certified on-site- mobile analytical laboratory/drilling contractor. The SVS included advancing five soil vapor borings (SV- 1, SV-2, SV-3, SV-4 and SV-5) and collection of soil vapor samples from five feet and ten feet bgs from all five borings. SV-1 thru SV-4 were advanced adjacent to the four soil borings previously discussed and SV-5 was advanced as a kick-out sample point further east of SV-2. The soil vapor probes were advanced and samples were collected using field procedures consistent with the California Department of Toxic Substance Control’s (DTSC’s)Interim Final Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air (DTSC Guidance) dated February 2020. Soil vapor samples were collected and analyzed for VOCs by U.S. EPA Method 8260B. One duplicate sample was also collected and analyzed Proposed Residential Property Project No. 024-23051 Bakersfield, California Page No. 4 of 6 KRAZAN & ASSOCIATES, INC. With Offices Serving the Western United States 024-23051 Prop Development Phase II Report Final.docx for VOCs. The results of the SVS are summarized in Table II and are discussed below. The complete Optimal laboratory analytical report is included as Attachment A (refer to the Optimal report for tabulated results and a list of VOC analytes that were analyzed for during this investigation). SOIL VAPOR SURVEY FINDINGS In summary, benzene was reported in four (4) of the eleven (11) soil vapor samples at or above the laboratory reporting limit (RL) of 3.0 micrograms per cubic meter (µg/m3), which were above the SFRWQCB Tier 1 ESL of 3.2 µg/m3. The benzene results are presented below. Based on these results, Krazan recommended that the data be evaluated by a certified toxicologist to determine whether reported concentrations of benzene detected in soil vapor at the site are within levels considered acceptable to California health and environmental protection agencies. Other than benzene, no other VOCs were detected at or above the laboratory’s RLs. SV-1 Benzene was not detected at or above the RL of 3.0 µg/m3 in sample SV-1-5’. Benzene was detected in sample SV-1-10’ at 31 µg/m3. SV-2 Benzene was detected in samples SV-2-5’ and SV-2-10’ at 122 µg/m3and 51 µg/m3, respectively. SV-3 Benzene was not detected at or above the RL of 3.0 µg/m3 in samples SV-3-5’ and SV-3-10’. SV-4 Benzene was not detected at or above the RL of 3.0 µg/m3 in samples SV-4-5’, SV-4-10’ and SV-4-10’ (Dup). SV-5 Benzene was not detected at or above the RL of 3.0 µg/m3 in sample SV-5-5’. Benzene was detected in sample SV-5-10’ at 19 µg/m3. VIRE FINDINGS Enviro-Tox Services Inc. (Enviro-Tox) conducted a VIRE for the subject site. Risk characterization involves estimating the magnitude of the potential adverse health effects that could occur due to chronic, long-term exposure to chemicals identified in soil vapor at the site. The VIRE is presented in the Technical Memorandum dated July 25, 2023 and is included as Attachment C. The risk characterization is based on the results of the dose-response (toxicity) and exposure assessment. The VIRE findings note that the soil vapor survey results indicated that only traces of benzene remain in soil vapor at the subject site. The potential for benzene vapor intrusion into a hypothetical residential building was evaluated in this VIRE. The maximum cancer risk estimated to result from unmitigated vapor intrusion into a hypothetical residential building was 4E-06. This estimated cancer risk is slightly higher than the benchmark of 1E-06 established by the DTSC. However, it is well below the known cancer risk for the United States population and the estimated non-cancer hazard was within levels considered acceptable to California health and environmental protection agencies. The VIRE notes that the lateral extent of benzene impacts is limited to the area immediately around soil vapor sample SV-2 and that the kickout sample SV-5 was reported with only trace concentrations at 10 feet bgs. Proposed Residential Property Project No. 024-23051 Bakersfield, California Page No. 5 of 6 KRAZAN & ASSOCIATES, INC. With Offices Serving the Western United States 024-23051 Prop Development Phase II Report Final.docx The VIRE additionally, notes that benzene is a chemical commonly found in urban environmental and is subject to biodegradation (Cal-EPA, 2023). Since the vertical and lateral extent of the benzene impacts are limited to a small area the volume of soil, the benzene emissions from such a small area are likely to attenuate over time to insignificant levels. Therefore, based on the results of the soil vapor survey and the results of this VIRE, it can be concluded that benzene detected in soil is limited in area and volume and does not appear to pose a significant risk to human health or the environment. PHASE II LIMITED SOIL, SOIL VAPOR ASSESSMENT AND VIRE CONCLUSIONS AND RECOMMENDATIONS The results of the analysis for the soil samples collected and analyzed from the subject site indicates TEPH concentrations were reported below regulatory action levels.Additionally, all soil samples analyzed were reported as ND for BTEX. Therefore, no further investigation appears warranted with respect to impacts to soil. Additionally, the soil vapor survey results indicated that only concentrations of benzene remain in soil vapor within a very limited area, and since the vertical and lateral extent of the benzene impacts are limited to a small area, the benzene emissions are likely to attenuate over time to insignificant levels. Based on the results of the VIRE, soil vapor at the subject site is within levels considered acceptable to California health and environmental protection agencies. Therefore, no further investigation appears warranted with respect to potential soil vapor migration to the site. Proposed Residential Property Project No. 024-23051 Bakersfield, California Page No. 6 of 6 KRAZAN & ASSOCIATES, INC. With Offices Serving the Western United States 024-23051 Prop Development Phase II Report Final.docx CLOSING We appreciate the opportunity to be of service. If you have any questions regarding this report, or if we can be of further assistance, please feel free to contact the undersigned at 661 837-9200 Respectfully Submitted, KRAZAN & ASSOCIATES, INC. Trenton J. Westerson Staff Scientist Mark D. Edwards, PG 7714 Senior Project Manager TJW/MDE/mlt Attachments: Table I Table II Figure 1 Attachment A – Laboratory Analytical Reports Attachment B – Enviro-Tox VIRE Report 07/2025 SB-1 -20'SB-1 -25'SB-1 -30'SB-2 -20'SB-2 -25'SB-2 -30'SB-3 -20'SB-3 -25'SB-3 -30'SB-4-20'SB-4-25'SB-4-30' COCs RL ESL Benzene 0.0025 0.33 ND ND ND ND ND ND ND ND ND ND ND ND Toluene 0.0025 1100 ND ND ND ND ND ND ND ND ND ND ND ND Ethylbenzene 0.0025 5.9 ND ND ND ND ND ND ND ND ND ND ND ND Xylenes 0.005 580 ND ND ND ND ND ND ND ND ND ND ND ND TPH-g 10 430 ND ND ND ND ND ND ND ND ND ND ND ND TPH-d 10 260 ND ND ND 43 44 42 46 ND 42 43 40 38 TPH-o 10 12000 ND ND 18 ND 29 22 19 ND 18 ND 16 25 COCs = Constituents of concern ND = None Detected at or above the Laboratory Reporting Limit RL = Laboratory Reporting Limit ESL = Environmental Screening Level, Residential Shallow Soil Exposure TPH-g = Total petroleum hydrocarbons in gas TPH-d = Total petroleum hydrocarbons in diesel TPH-o = Total petroleum hydrocarbons in motor oil Note: TEPH Total Extractable Petroleum Hydrocarbons is the sum total of TPH-g, d, and o Note: TPH-cc Total Petroleum Hydrocarbons, carbon chain analysis (includes TPH-g, d, and o) Sampling Conducted on 06/22/2023 RESULTS (Reported in mg/kg) Soil Samples TABLE I 024-23051 Panama Lane and Buena Vista Soil Sample Analytical Results BTEX by EPA Method 8260B; TPH-cc by EPA Method 8015B SV-1-5'SV-1-10'SV-2-5'SV-2-10'SV-3-5'SV-3-10'SV-4-5'SV-4-10'SV-4-10' (Dup)SV-5-5'SV-5-10' Benzene 3.0 3.2 ND 31 122 51 ND ND ND ND ND ND 19 RL = Laboratory Reporting Limit ESL = Environmental Screening Level, Subslab/Soil Gas Vapor Intrusion ND = Not Detected at or above the Laboratory Reporting Limit Note: All other VOCs were reported as Not Detected at or above the Laboratory Reporting Limit VOCs TABLE II 024-23051 Panama Lane and Buena Vista Soil Vapor Analytical Results RL ESL Volatile Organic Compounds by EPA Method 8260B Sampling Conducted 07/06/2023 RESULTS (Reported in µg/m^3) Maxar, Microsoft Date: August 2023 Approved By: ME Figure No: 1 Scale: 1"=125' Drawn By: TW Project No: 024-23051 Site Map Proposed Residential Property Northeast Corner of Panama Lane and Buena Vista Road APN 544-030-04 (17.54 Acres) Bakersfield, California ± 0 125 25062.5 US Feet Subject Site Boundary Soil Sample Soil Vapor Sample Panama LaneBuena Vista RoadSV-3 SV-2 SV-1 SV-4 SV-5 SB-4 SB-3 SB-1 SB-2 Attachment A 1667 Cross Bridge Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-62352369 Rutland Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-6235 OPTIMAL TECHNOLOGYSpecializing in Environmental Field Services Optimal Technology LH.indd 1 8/26/2008 2:46:55 PM July 7, 2023 Bill Cooper Krazan & Associates, Inc. 2205 Coy Avenue Bakersfield, CA 93307 Dear Bill: This letter presents the results of the soil vapor investigation conducted by Optimal Technology (Optimal), for Krazan & Associates, Inc. on July 6, 2023. The study was performed at the Northeast corner of Panama Lane & Buena Vista Road in Bakersfield, California. Optimal was contracted to perform a soil vapor survey at this site to screen for possible chlorinated solvents and aromatic hydrocarbons. The primary objective of this soil vapor investigation was to determine if soil vapor contamination is present in the subsurface soil. Gas Sampling Method Gas sampling was performed by hydraulically pushing soil gas probes to a depth of 5.0-10.0 feet below ground surface (bgs). An electric rotary hammer drill was used to drill a 1.0-inch diameter hole through the overlying surface to allow probe placement when required. The same electric hammer drill was used to push probes in areas of resistance during placement. At each sampling location, an electric vacuum pump set to draw 0.2 liters per minute (L/min) of soil vapor was attached to the probe and purged prior to sample collection. Vapor samples were obtained in gas-tight syringes by drawing the sample through a luer-lock connection which connects the sampling probe and the vacuum pump. Samples were immediately injected into the gas chromatograph/purge and trap after collection. New tubing was used at each sampling point to prevent cross contamination. All analyses were performed on a laboratory grade Agilent model 6890N gas chromatograph equipped with an Agilent model 5973N Mass Spectra Detector and Tekmar LSC 3100 Purge and Trap. A Restek column using helium as the carrier gas was used to perform all analysis. All results were collected on a personal computer utilizing Agilent's MS and chromatographic data collection and handling system. Page 2 of 3 Quality Assurance 5-Point Calibration The initial five-point calibration consisted of 20, 50, 100, 200 and 500 ul injections of the calibration standard. A calibration factor on each analyte was generated using a best fit line method using the Agilent data system. If the r2 factor generated from this line was not greater than 0.990, an additional five-point calibration would have been performed. Method reporting limits were calculated to be 1-1000 micrograms per cubic meter (ug/m3) for the individual compounds. A daily calibration check was performed using a pre-mixed standard supplied by Scotty Analyzed Gases. The standard contained common halogenated solvents and aromatic hydrocarbons (see Table 1). The individual compound concentrations in the standards ranged between 0.025 nanograms per microliter (ng/ul) and 0.25 ng/ul. TABLE 1 Benzene 1,2-Dichloroethane Tetrachloroethene Bromomethane 1,1-Dichloroethene Toluene Carbon Tetrachloride cis-1,2-Dichloroethene 1,1,1-Trichloroethane Chlorobenzene trans-1,2-Dichloroethene 1,1,2-Trichloroethane Chloroethane 2,2-Dichloropropane Trichloroethene Chloromethane Ethylbenzene Trichlorofluoromethane Chloroform Methylene Chloride Vinyl Chloride Dibromomethane Styrene m/p-Xylene Dichlorodifluoromethane 1,1,1,2-Tetrachloroethane o-Xylene 1,1-Dichloroethane 1,1,2,2-Tetrachloroethane Isobutane Sample Replicates A replicate analysis (duplicate) was run to evaluate the reproducibility of the sampling system and instrument. The difference between samples did not vary more than 20%. Equipment Blanks Blanks were run at the beginning of each workday and after calibrations. The blanks were collected using an ambient air sample. These blanks checked the septum, syringe, GC column, GC detector and the ambient air. Contamination was not found in any of the blanks analyzed during this investigation. Blank results are given along with the sample results. Purge Volume The standard purge volume of three volumes was purged in accordance with the July 2015 DTSC/RWQCB Advisory for Active Soil Gas Investigations. Tracer Gas Leak Test A tracer gas was applied to the soil gas probes at each point of connection in which ambient air could enter the sampling system. These points include the top of the sampling probe where the Page 3 of 3 tubing meets the probe connection and the surface bentonite seals. Isobutane was used as the tracer gas. No Isobutane was found in any of the samples collected. Shut-in Test A shut-in test was conducted prior to purging or sampling each location to check for leaks in the above-ground sampling system. The system was evaluated to a minimum measured vacuum of 100 inches of water. The vacuum gauge was calibrated and sensitive enough to indicate a water pressure change of at least 0.5 inches. Scope of Work To achieve the objective of this investigation using field procedures consistent with the California Department of Toxic Substance Control’s (DTSC’s) Interim Final Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air (DTSC Guidance) dated February 2020 a total of 11 vapor samples were collected from 5 locations at the site. Sampling depths, vacuum readings, purge volume and sampling volumes are given on the analytical results page. All the collected vapor samples were analyzed on-site using Optimal’s mobile laboratory. Subsurface Conditions Subsurface soil conditions offered sampling flows at 0” water vacuum. Results During this vapor investigation, four samples contained levels of Benzene ranging from 19 ug/m3 to 122 ug/m3. None of the other compounds listed in Table 1 above were detected above the listed reporting limits. A complete table of analytical results is included with this report. Disclaimer All conclusions presented in this letter are based solely on the information collected by the soil vapor survey conducted by Optimal Technology. Soil vapor testing is only a subsurface screening tool and does not represent actual contaminant concentrations in either the soil and/or groundwater. We enjoyed working with you on this project and look forward to future projects. If you have any questions, please contact me at (877) 764-5427. Sincerely, Attila Baly Project Manager 1667 Cross Bridge Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-62352369 Rutland Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-6235 OPTIMAL TECHNOLOGYSpecializing in Environmental Field Services Optimal Technology LH.indd 1 8/26/2008 2:46:55 PM SOIL VAPOR RESULTS Site Name:NE Corner of Panama Lane & Buena Vista Rd.,Lab Name:Optimal Technology Date:7/6/23 Bakersfield, CA Analyst:A. Baly Collector:A. Baly Agilent 6890NF Method:Modified EPA 8260B Agilent 5973N Mass Spectrometer Page:1 of 2 BLANK-1 SV-1-5 SV-1-10 SV-2-5 SV-2-10 SV-3-5 SV-3-10 SV-4-5 Sampling Depth (Ft.) N/A 5.0 10.0 5.0 10.0 5.0 10.0 5.0 Purge Volume (ml) N/A 1,500 2,250 1,500 2,250 1,500 2,250 1,500 Vacuum (in. of Water)N/A0000000 Injection Volume (ul) 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 Dilution Factor 11111111 COMPOUND REP. LIMIT CONC (ug/m3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) Benzene 3NDND31 122 51 ND ND ND Bromomethane 150 ND ND ND ND ND ND ND ND Carbon Tetrachloride 2 NDNDNDNDNDNDNDND Chlorobenzene 1000 ND ND ND ND ND ND ND ND Chloroethane 1000 ND ND ND ND ND ND ND ND Chloromethane 1000 ND ND ND ND ND ND ND ND Chloroform 4 NDNDNDNDNDNDNDND Dibromomethane 1000 ND ND ND ND ND ND ND ND Dichlorodifluoromethane 1000 ND ND ND ND ND ND ND ND 1,1-Dichloroethane 50 ND ND ND ND ND ND ND ND 1,2-Dichloroethane 3 NDNDNDNDNDNDNDND 1,1-Dichloroethene 1000 ND ND ND ND ND ND ND ND cis-1,2-Dichloroethene 200 ND ND ND ND ND ND ND ND trans-1,2-Dichloroethene 1000 ND ND ND ND ND ND ND ND 2,2-Dichloropropane 1000 ND ND ND ND ND ND ND ND Ethylbenzene 30 ND ND ND ND ND ND ND ND Methylene Chloride 30 ND ND ND ND ND ND ND ND Styrene 1000 ND ND ND ND ND ND ND ND 1,1,1,2-Tetrachloroethane 10 ND ND ND ND ND ND ND ND 1,1,2,2-Tetrachloroethane 1 NDNDNDNDNDNDNDND Tetrachloroethene (PCE) 10 ND ND ND ND ND ND ND ND Toluene 1000 ND ND ND ND ND ND ND ND 1,1,1-Trichloroethane 1000 ND ND ND ND ND ND ND ND 1,1,2-Trichloroethane 5 NDNDNDNDNDNDNDND Trichloroethene (TCE) 10 ND ND ND ND ND ND ND ND Trichlorofluoromethane 1000 ND ND ND ND ND ND ND ND Vinyl Chloride 1 NDNDNDNDNDNDNDND m/p-Xylene 1000 ND ND ND ND ND ND ND ND o-Xylene 1000 ND ND ND ND ND ND ND ND TPH-g 5000 ND ND ND ND ND ND ND ND Isobutane (Tracer Gas) 1000 ND ND ND ND ND ND ND ND Note: ND = Below Listed Reporting Limit Inst. ID: Detector: SAMPLE ID 1667 Cross Bridge Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-62352369 Rutland Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-6235 OPTIMAL TECHNOLOGYSpecializing in Environmental Field Services Optimal Technology LH.indd 1 8/26/2008 2:46:55 PM SOIL VAPOR RESULTS Site Name:NE Corner of Panama Lane & Buena Vista Rd.,Lab Name:Optimal Technology Date:7/6/23 Bakersfield, CA Analyst:A. Baly Collector:A. Baly Agilent 6890NF Method:Modified EPA 8260B Agilent 5973N Mass Spectrometer Page:2 of 2 SV-4-10 SV-4-10 Dup SV-5-5 SV-5-10 Sampling Depth (Ft.) 10.0 10.0 5.0 10.0 Purge Volume (ml) 2,250 2,250 1,500 2,250 Vacuum (in. of Water)0000 Injection Volume (ul) 100,000 100,000 100,000 100,000 Dilution Factor 1111 COMPOUND REP. LIMIT CONC (ug/m3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) Benzene 3 NDNDND 19 Bromomethane 150 ND ND ND ND Carbon Tetrachloride 2 NDNDNDND Chlorobenzene 1000 ND ND ND ND Chloroethane 1000 ND ND ND ND Chloromethane 1000 ND ND ND ND Chloroform 4 NDNDNDND Dibromomethane 1000 ND ND ND ND Dichlorodifluoromethane 1000 ND ND ND ND 1,1-Dichloroethane 50 ND ND ND ND 1,2-Dichloroethane 3 NDNDNDND 1,1-Dichloroethene 1000 ND ND ND ND cis-1,2-Dichloroethene 200 ND ND ND ND trans-1,2-Dichloroethene 1000 ND ND ND ND 2,2-Dichloropropane 1000 ND ND ND ND Ethylbenzene 30 ND ND ND ND Methylene Chloride 30 ND ND ND ND Styrene 1000 ND ND ND ND 1,1,1,2-Tetrachloroethane 10 ND ND ND ND 1,1,2,2-Tetrachloroethane 1 NDNDNDND Tetrachloroethene (PCE) 10 ND ND ND ND Toluene 1000 ND ND ND ND 1,1,1-Trichloroethane 1000 ND ND ND ND 1,1,2-Trichloroethane 5 NDNDNDND Trichloroethene (TCE) 10 ND ND ND ND Trichlorofluoromethane 1000 ND ND ND ND Vinyl Chloride 1 NDNDNDND m/p-Xylene 1000 ND ND ND ND o-Xylene 1000 ND ND ND ND TPH-g 5000 ND ND ND ND Isobutane (Tracer Gas) 1000 ND ND ND ND Note: ND = Below Listed Reporting Limit Inst. ID: Detector: SAMPLE ID 1667 Cross Bridge Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-62352369 Rutland Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-6235 OPTIMAL TECHNOLOGYSpecializing in Environmental Field Services Optimal Technology LH.indd 1 8/26/2008 2:46:55 PM CHAIN OF CUSTODY FORM Page: 1 of 1 Site Name/Number NE Corner of Panama Lane & Buena Vista Rd.,PO# / Project Ref# Site Address Bakersfield, CA Company Name Contact Person(s): Phone#Email: Comments: TESTS REQUIRED (please mark with an "X") Sample Sampling Date Time Soil Gas Soil Gas Soil Gas Identification Device Collected Collected Mod 8260B Mod 8021B Mod 8015 BLANK-1 Syringe 7/6/23 8:05 AM x SV-1-5 Syringe 7/6/23 8:26 AM x SV-1-10 Syringe 7/6/23 8:45 AM x SV-2-5 Syringe 7/6/23 9:06 AM x SV-2-10 Syringe 7/6/23 9:28 AM x SV-3-5 Syringe 7/6/23 9:50 AM x SV-3-10 Syringe 7/6/23 10:18 AM x SV-4-5 Syringe 7/6/23 10:40 AM x SV-4-10 Syringe 7/6/23 11:06 AM x SV-4-10 Dup Syringe 7/6/23 11:06 AM x SV-5-5 Syringe 7/6/23 11:35 AM x SV-5-10 Syringe 7/6/23 11:54 AM x Collected & Tested by: Notes Attachment B Date: July 31, 2023 To: Mr. Bill Cooper, P.G. Environmental Manager Krazan & Associates, Inc. 2205 Coy Avenue Bakersfield, California 93307 From: Heriberto Robles, Ph.D., D.A.B.T. Subject: Vapor Intrusion Risk Evaluation Vacant Property Northeast Corner of Panama Lane and Buena Vista Road Bakersfield, California Introduction At the request of Krazan & Associates, Inc. (Krazan), Enviro-Tox Services Inc. (Enviro-Tox) conducted a Vapor Intrusion Risk Evaluation (VIRE) for the vacant property located at the northeast corner of Panama Lane and Buena Vista Road in Bakersfield, California (Site). The purpose of this VIRE is to assess whether traces of the chemical benzene detected in soil gas under the Site are within levels considered acceptable to California health and environmental protection agencies. Soil Gas Survey On July 6, 2023, using a mobile laboratory/drilling contractor (Optimal Technology), five temporary soil vapor probes were advanced at the Site to a depth of 5 and 10 feet below ground surface (bgs). Eleven soil gas samples were collected and analyzed for volatile organic compounds (VOCs) by United States Environmental Protection Agency (USEPA) Method 8260B. Optimal conducted the sampling in accordance with DTSC Guidance (2023). The only chemical detected in soil gas was benzene. A copy of the laboratory analytical report is included in Attachment A. Vapor Intrusion Risk Evaluation Methodology Risk characterization involves estimating the magnitude of the potential adverse health effects that could occur due to chronic, long-term exposure to chemicals identified in soil gas at the site. The risk characterization is based on the results of the dose-response (toxicity) and exposure assessment. It is known that chemicals may migrate through environmental media from their source to a point where human receptors may be exposed. Therefore, it was necessary to determine if the detected benzene – given its residual concentrations, locations, soil physical characteristics, weather conditions, etc. – could potentially migrate up to the surface (where human receptors may be exposed). Screening-level models were used to predict indoor air concentrations that may result from the chemical vapors potentially released from soil gas under the Site. The estimated vapor flux and indoor Technical Memorandum July 31, 2023 Page 2 of 5 air concentrations were then used to compute potential health risks that may result from onsite exposures. For the purposes of this evaluation, it was assumed that the land use could be residential. The only exposure pathway that was considered complete was the volatilization of benzene from soil gas and the subsequent emission to indoor air. In this evaluation, the maximum benzene concentration detected (122 micrograms per cubic meter [ug/m3]) was considered representative of the prevailing benzene concentrations present in soil gas under the Site. The DTSC guidance recommends that multiple lines of evidence be used when evaluating the potential risk and hazards posed by vapor intrusion. DTSC recommends that the indoor air chemical concentrations that can result from vapor intrusion be estimated using the following equation: 𝐴𝐹= 𝐶!"#$$% 𝐶&$!’ )*& Where: AF = Attenuation factor (unitless) Cindoor = Indoor air concentration (ug/m3) Csoil gas = Soil gas concentration (ug/m3) Using the above equation, the indoor air chemical concentration can be estimated by multiplying the known soil gas concentration by the default attenuation factor (AF). In accordance with the DTSC’s Supplemental Vapor Intrusion Guidance, a default AF of 0.003 was used in the evaluation. This AF was derived from the general default AF of 0.03 and the additional AF of 0.1 recommended for petroleum-derived chemicals in Attachment 2 of the DTSC (2023) guidance. The estimated indoor air benzene concentration is presented in Table 1. Risk Characterization This section describes the methods used to quantify the exposure concentration (EC) for potential receptors at a hypothetical onsite building. The estimated benzene EC was used to estimate the potential for carcinogenic health risks and non-carcinogenic adverse health effects. The potential inhalation exposures were calculated using the following equation (USEPA, 2009): Where: EC = Exposure concentration, ug/m3 CA = Chemical concentration in air, ug/m3 ET = Exposure time, hours/day EF = Exposure frequency, days/year € EC = CA • ET • EF • ED AT Technical Memorandum July 31, 2023 Page 3 of 5 ED = Exposure duration, years AT = Averaging time, hours (used the equivalent of 70 years for carcinogens and the same value as ED for non-carcinogens). Inhalation intake factors were combined with the estimated benzene indoor air concentration (CA; Table 1) to obtain the exposure concentration for hypothetical onsite receptors. Exposure parameters used to characterize hypothetical residential receptors are presented in Table 2. Default exposure parameters were taken from DTSC (2019) guidance. Non-Carcinogenic Health Hazard Evaluation The evaluation of non-carcinogenic health hazards began with a calculation of the hazard quotient or HQ for each chemical. The HQ is defined as the ratio of the exposure concentration (EC) to the reference concentration (RfC). The HQ can be expressed according to the following equation: Where: HQ = Hazard quotient, unitless EC = Exposure concentration, ug/m3 RfC = Reference concentration, ug/m3 The estimated HQ was compared to an acceptable hazard level. Implicit in the HQ is the assumption of a threshold level of exposure below which no adverse effects are expected to occur. For example, if the HQ exceeds unity (because site-specific exposure exceeds the RfC), then the potential for non- cancer adverse effects may exist. In general, the greater the value above 1.0, the greater the potential hazard. In contrast, HQs of less than 1.0 indicate that no adverse health effects are expected to occur from exposure to chemicals at the Site. According to the USEPA (1989), if the HQ is less than 1, there is no concern for potential chronic adverse health effects from the chemical exposures. The HQ estimated for benzene was 0.1 (Table 3). This estimated HQ is considered acceptable to California health and environmental protection agencies. Cancer Risk Estimates The cancer risk was estimated as the incremental probability of an individual developing cancer over a lifetime as a result of exposure to a potential carcinogen (i.e., incremental or excess individual lifetime cancer risk; USEPA, 1989). The cancer risk was calculated in accordance with DTSC (2015) and USEPA (1989) guidelines. Where: Risk = Upper bound incremental lifetime carcinogenic risk, unitless EC = Exposure concentration, ug/m3 € HQ = EC RfC € Risk = EC • IUR Technical Memorandum July 31, 2023 Page 4 of 5 IUR = Inhalation unit risk, (ug/m3)-1 The excess cancer risk was compared to the risk level considered acceptable by federal and state regulatory agencies. The target cancer risk level identified by the DTSC in the Preliminary Endangerment Assessment (PEA) Guidance Manual is 1 in 1 million (1.0E-06). However, the USEPA has established acceptable incremental cancer risk levels to be within the risk range of 1 in 10,000 (1.0E-04) and 1.0E-06; risks greater than 1.0E-04 are generally considered unacceptable. Using the maximum detected benzene concentration, the cancer risk was estimated to be 4E-06 (Table 4). This estimated cancer risk is slightly higher than the cancer risk benchmark value of 1E-06 established by the DTSC (2015) for unrestricted land use. Conclusions and Recommendations Krazan’s soil gas survey results indicated that only traces of benzene remain in soil gas at the Site (Attachment A). Most of the detections were found at a depth of 10 feet bgs and only one of five samples collected at a depth of five feet bgs contained benzene at detectable concentrations (Attachment A). The potential for benzene vapor intrusion into a hypothetical residential building was evaluated in this VIRE. The maximum cancer risk estimated to result from unmitigated vapor intrusion into a hypothetical residential building was 4E-06. This estimated cancer risk is well below the known cancer risk for the United States population and slightly exceeds the cancer risk benchmark of 1E-06 established by the DTSC (2015) for unrestricted land use. The estimated non-cancer hazard was within levels considered acceptable to California health and environmental protection agencies. It should be noted that the lateral extent of benzene impacts is limited to the area immediately around soil gas sample SV-2 as only this sample contained benzene at detectable concentrations (Attachment A). Furthermore, benzene is a chemical commonly found in urban environments and is subject to biodegradation (Cal-EPA, 2023). Since the vertical and lateral extent of benzene impacts are limited to a small area and volume of soil, the benzene emissions from such a small area are likely to attenuate overtime down to insignificant levels. This VIRE was based on conservative (health-protective) assumptions, estimates, models, and parameters. Therefore, the results are not absolute estimates of health risks at the Site but are health-protective estimates. The conclusions and recommendations presented in this report are professional opinions based solely upon the data described in this report. They are intended exclusively for the purpose outlined herein and the property’s location and project indicated. The scope of services performed in the execution of this investigation may not be appropriate to satisfy the needs of users other than Krazan and its client. Any use or reuse of this document or the findings, conclusions, or recommendations presented herein is at the sole risk of said user. Technical Memorandum July 31, 2023 Page 5 of 5 No express or implied representation or warranty is included or intended in this report except that the work was performed within the limits prescribed by Krazan with the customary thoroughness and competence of professionals working in the same area on similar projects. Attachments Table 1. Indoor Air Concentrations Estimated Using an Attenuation Factor of 0.003 Table 2. Exposure Parameters for Onsite Receptors Table 3. Health Hazards from Inhalation of Indoor Air Table 4. Cancer Risks from Inhalation of Indoor Air Attachment A – Optimal Technologies Laboratory Report References DTSC. 2011. Interim Final, Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air. February. DTSC. 2015. Preliminary Endangerment Assessment Guidance Manual. State of California Environmental Protection Agency, Sacramento, California. DTSC. 2019. HERO HHRA Note Number: 1, Default HHRA Exposure Parameters. DTSC. 2023. Supplemental Guidance: Screening and Evaluating Vapor Intrusion. Final Draft. February. USEPA. 1989. Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual (Part A). Office of Emergency and Remedial Response. Washington, D.C. USEPA. 2009. Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation Manual (Part F, Supplemental Guidance for Inhalation Risk Assessment). EPA-540-R-070- 002. Final. January. This memorandum was prepared by: Enviro-Tox Services, Inc. ____________________________ Heriberto Robles, Ph. D., D.A.B.T. Principal Toxicologist TABLES Benzene 71432 122 3.66E-01 Notes: Attenuation factor (unitless) =0.003 µg/m3 = micrograms per cubic meter NA = Not applicable or not available Chemical of Potential Concern (COPC) CAS Number Maximum Detected Soil Gas Concentration (µg/m3) Estimated Indoor Chemical Air Concentration (ug/m3) Table 1 Indoor Air Concentrations Estimated Using a Default Attenuation Factor of 0.003 Northeast Corner of Panama Lane and Buena Vista Road Bakersfield, California Exposure Parameters Adult Resident Child Resident Source Chemical Concentration in Air (CA)----chemical-specific Exposure Frequency (EF)days/year 350 350 HERO 2019 Exposure Duration (ED)years 20 6 HERO 2019 Exposure Time (ET)hr/day 24 24 Default Averaging Time for Noncarcinogens (ATn)hours 175,200 52,560 USEPA 2009 Averaging Time for Carcinogens (ATc)hours 613,200 613,200 USEPA 2009 Table 2 Exposure Parameters for Onsite Receptors Northeast Corner of Panama Lane and Buena Vista Road Bakersfield, California Exposure/Site Specific Parameters Units Residential Exposure Scenario Hazard index (unitless) Adult Res.Child Res.Child Res. Benzene 3.7E-01 3.0E+00 4.E-01 4.E-01 1.E-01 Notes: Hazard Quotients estimated assuming a Vapor Intrusion Attenuation Factor of 0.003. COPC Indoor Air Conc. (ug/m3) Inhalation Reference Dose (ug/m3) Table 3 Health Hazards from Inhalation of Indoor Air Estimated Using a Default Attenuation Factor of 0.003 Northeast Corner of Panama Lane and Buena Vista Road Bakersfield, California Average Exposure Conc_nc (ug/m3) Residential Exposure Scenario Adult Resident Child Resident Adult & Child Resident Benzene 3.7E-01 2.9E-05 1.E-01 3.E-02 4.E-06 Notes: Cancer risks estimated assuming a Vapor Intrusion Attenuation Factor of 0.003. COPC Table 4 Cancer Risks from Inhalation of Indoor Air Estimated Using a Default Attenuation Factor of 0.003 Northeast Corner of Panama Lane and Buena Vista Road Bakersfield, California Indoor Air Chemical Conc. (ug/m3) Inhalation Slope Factor (ug/m3)-1 Lifetime Exposure Conc_c (ug/m3) Cancer Risk (Unitless) ATTACHMENTS ATTACHMENT A Optimal Technologies Laboratory Report 1667 Cross Bridge Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-62352369 Rutland Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-6235 OPTIMAL TECHNOLOGYSpecializing in Environmental Field Services Optimal Technology LH.indd 1 8/26/2008 2:46:55 PM July 7, 2023 Bill Cooper Krazan & Associates, Inc. 2205 Coy Avenue Bakersfield, CA 93307 Dear Bill: This letter presents the results of the soil vapor investigation conducted by Optimal Technology (Optimal), for Krazan & Associates, Inc. on July 6, 2023. The study was performed at the Northeast corner of Panama Lane & Buena Vista Road in Bakersfield, California. Optimal was contracted to perform a soil vapor survey at this site to screen for possible chlorinated solvents and aromatic hydrocarbons. The primary objective of this soil vapor investigation was to determine if soil vapor contamination is present in the subsurface soil. Gas Sampling Method Gas sampling was performed by hydraulically pushing soil gas probes to a depth of 5.0-10.0 feet below ground surface (bgs). An electric rotary hammer drill was used to drill a 1.0-inch diameter hole through the overlying surface to allow probe placement when required. The same electric hammer drill was used to push probes in areas of resistance during placement. At each sampling location, an electric vacuum pump set to draw 0.2 liters per minute (L/min) of soil vapor was attached to the probe and purged prior to sample collection. Vapor samples were obtained in gas-tight syringes by drawing the sample through a luer-lock connection which connects the sampling probe and the vacuum pump. Samples were immediately injected into the gas chromatograph/purge and trap after collection. New tubing was used at each sampling point to prevent cross contamination. All analyses were performed on a laboratory grade Agilent model 6890N gas chromatograph equipped with an Agilent model 5973N Mass Spectra Detector and Tekmar LSC 3100 Purge and Trap. A Restek column using helium as the carrier gas was used to perform all analysis. All results were collected on a personal computer utilizing Agilent's MS and chromatographic data collection and handling system. Page 2 of 3 Quality Assurance 5-Point Calibration The initial five-point calibration consisted of 20, 50, 100, 200 and 500 ul injections of the calibration standard. A calibration factor on each analyte was generated using a best fit line method using the Agilent data system. If the r2 factor generated from this line was not greater than 0.990, an additional five-point calibration would have been performed. Method reporting limits were calculated to be 1-1000 micrograms per cubic meter (ug/m3) for the individual compounds. A daily calibration check was performed using a pre-mixed standard supplied by Scotty Analyzed Gases. The standard contained common halogenated solvents and aromatic hydrocarbons (see Table 1). The individual compound concentrations in the standards ranged between 0.025 nanograms per microliter (ng/ul) and 0.25 ng/ul. TABLE 1 Benzene 1,2-Dichloroethane Tetrachloroethene Bromomethane 1,1-Dichloroethene Toluene Carbon Tetrachloride cis-1,2-Dichloroethene 1,1,1-Trichloroethane Chlorobenzene trans-1,2-Dichloroethene 1,1,2-Trichloroethane Chloroethane 2,2-Dichloropropane Trichloroethene Chloromethane Ethylbenzene Trichlorofluoromethane Chloroform Methylene Chloride Vinyl Chloride Dibromomethane Styrene m/p-Xylene Dichlorodifluoromethane 1,1,1,2-Tetrachloroethane o-Xylene 1,1-Dichloroethane 1,1,2,2-Tetrachloroethane Isobutane Sample Replicates A replicate analysis (duplicate) was run to evaluate the reproducibility of the sampling system and instrument. The difference between samples did not vary more than 20%. Equipment Blanks Blanks were run at the beginning of each workday and after calibrations. The blanks were collected using an ambient air sample. These blanks checked the septum, syringe, GC column, GC detector and the ambient air. Contamination was not found in any of the blanks analyzed during this investigation. Blank results are given along with the sample results. Purge Volume The standard purge volume of three volumes was purged in accordance with the July 2015 DTSC/RWQCB Advisory for Active Soil Gas Investigations. Tracer Gas Leak Test A tracer gas was applied to the soil gas probes at each point of connection in which ambient air could enter the sampling system. These points include the top of the sampling probe where the Page 3 of 3 tubing meets the probe connection and the surface bentonite seals. Isobutane was used as the tracer gas. No Isobutane was found in any of the samples collected. Shut-in Test A shut-in test was conducted prior to purging or sampling each location to check for leaks in the above-ground sampling system. The system was evaluated to a minimum measured vacuum of 100 inches of water. The vacuum gauge was calibrated and sensitive enough to indicate a water pressure change of at least 0.5 inches. Scope of Work To achieve the objective of this investigation using field procedures consistent with the California Department of Toxic Substance Control’s (DTSC’s) Interim Final Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air (DTSC Guidance) dated February 2020 a total of 11 vapor samples were collected from 5 locations at the site. Sampling depths, vacuum readings, purge volume and sampling volumes are given on the analytical results page. All the collected vapor samples were analyzed on-site using Optimal’s mobile laboratory. Subsurface Conditions Subsurface soil conditions offered sampling flows at 0” water vacuum. Results During this vapor investigation, four samples contained levels of Benzene ranging from 19 ug/m3 to 122 ug/m3. None of the other compounds listed in Table 1 above were detected above the listed reporting limits. A complete table of analytical results is included with this report. Disclaimer All conclusions presented in this letter are based solely on the information collected by the soil vapor survey conducted by Optimal Technology. Soil vapor testing is only a subsurface screening tool and does not represent actual contaminant concentrations in either the soil and/or groundwater. We enjoyed working with you on this project and look forward to future projects. If you have any questions, please contact me at (877) 764-5427. Sincerely, Attila Baly Project Manager 1667 Cross Bridge Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-62352369 Rutland Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-6235 OPTIMAL TECHNOLOGYSpecializing in Environmental Field Services Optimal Technology LH.indd 1 8/26/2008 2:46:55 PM SOIL VAPOR RESULTS Site Name:NE Corner of Panama Lane & Buena Vista Rd.,Lab Name:Optimal Technology Date:7/6/23 Bakersfield, CA Analyst:A. Baly Collector:A. Baly Agilent 6890NF Method:Modified EPA 8260B Agilent 5973N Mass Spectrometer Page:1 of 2 BLANK-1 SV-1-5 SV-1-10 SV-2-5 SV-2-10 SV-3-5 SV-3-10 SV-4-5 Sampling Depth (Ft.) N/A 5.0 10.0 5.0 10.0 5.0 10.0 5.0 Purge Volume (ml) N/A 1,500 2,250 1,500 2,250 1,500 2,250 1,500 Vacuum (in. of Water)N/A0000000 Injection Volume (ul) 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 Dilution Factor 11111111 COMPOUND REP. LIMIT CONC (ug/m3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) Benzene 3NDND31 122 51 ND ND ND Bromomethane 150 ND ND ND ND ND ND ND ND Carbon Tetrachloride 2 NDNDNDNDNDNDNDND Chlorobenzene 1000 ND ND ND ND ND ND ND ND Chloroethane 1000 ND ND ND ND ND ND ND ND Chloromethane 1000 ND ND ND ND ND ND ND ND Chloroform 4 NDNDNDNDNDNDNDND Dibromomethane 1000 ND ND ND ND ND ND ND ND Dichlorodifluoromethane 1000 ND ND ND ND ND ND ND ND 1,1-Dichloroethane 50 ND ND ND ND ND ND ND ND 1,2-Dichloroethane 3 NDNDNDNDNDNDNDND 1,1-Dichloroethene 1000 ND ND ND ND ND ND ND ND cis-1,2-Dichloroethene 200 ND ND ND ND ND ND ND ND trans-1,2-Dichloroethene 1000 ND ND ND ND ND ND ND ND 2,2-Dichloropropane 1000 ND ND ND ND ND ND ND ND Ethylbenzene 30 ND ND ND ND ND ND ND ND Methylene Chloride 30 ND ND ND ND ND ND ND ND Styrene 1000 ND ND ND ND ND ND ND ND 1,1,1,2-Tetrachloroethane 10 ND ND ND ND ND ND ND ND 1,1,2,2-Tetrachloroethane 1 NDNDNDNDNDNDNDND Tetrachloroethene (PCE) 10 ND ND ND ND ND ND ND ND Toluene 1000 ND ND ND ND ND ND ND ND 1,1,1-Trichloroethane 1000 ND ND ND ND ND ND ND ND 1,1,2-Trichloroethane 5 NDNDNDNDNDNDNDND Trichloroethene (TCE) 10 ND ND ND ND ND ND ND ND Trichlorofluoromethane 1000 ND ND ND ND ND ND ND ND Vinyl Chloride 1 NDNDNDNDNDNDNDND m/p-Xylene 1000 ND ND ND ND ND ND ND ND o-Xylene 1000 ND ND ND ND ND ND ND ND TPH-g 5000 ND ND ND ND ND ND ND ND Isobutane (Tracer Gas) 1000 ND ND ND ND ND ND ND ND Note: ND = Below Listed Reporting Limit Inst. ID: Detector: SAMPLE ID 1667 Cross Bridge Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-62352369 Rutland Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-6235 OPTIMAL TECHNOLOGYSpecializing in Environmental Field Services Optimal Technology LH.indd 1 8/26/2008 2:46:55 PM SOIL VAPOR RESULTS Site Name:NE Corner of Panama Lane & Buena Vista Rd.,Lab Name:Optimal Technology Date:7/6/23 Bakersfield, CA Analyst:A. Baly Collector:A. Baly Agilent 6890NF Method:Modified EPA 8260B Agilent 5973N Mass Spectrometer Page:2 of 2 SV-4-10 SV-4-10 Dup SV-5-5 SV-5-10 Sampling Depth (Ft.) 10.0 10.0 5.0 10.0 Purge Volume (ml) 2,250 2,250 1,500 2,250 Vacuum (in. of Water)0000 Injection Volume (ul) 100,000 100,000 100,000 100,000 Dilution Factor 1111 COMPOUND REP. LIMIT CONC (ug/m3) CONC (ug/m 3) CONC (ug/m 3) CONC (ug/m 3) Benzene 3 NDNDND 19 Bromomethane 150 ND ND ND ND Carbon Tetrachloride 2 NDNDNDND Chlorobenzene 1000 ND ND ND ND Chloroethane 1000 ND ND ND ND Chloromethane 1000 ND ND ND ND Chloroform 4 NDNDNDND Dibromomethane 1000 ND ND ND ND Dichlorodifluoromethane 1000 ND ND ND ND 1,1-Dichloroethane 50 ND ND ND ND 1,2-Dichloroethane 3 NDNDNDND 1,1-Dichloroethene 1000 ND ND ND ND cis-1,2-Dichloroethene 200 ND ND ND ND trans-1,2-Dichloroethene 1000 ND ND ND ND 2,2-Dichloropropane 1000 ND ND ND ND Ethylbenzene 30 ND ND ND ND Methylene Chloride 30 ND ND ND ND Styrene 1000 ND ND ND ND 1,1,1,2-Tetrachloroethane 10 ND ND ND ND 1,1,2,2-Tetrachloroethane 1 NDNDNDND Tetrachloroethene (PCE) 10 ND ND ND ND Toluene 1000 ND ND ND ND 1,1,1-Trichloroethane 1000 ND ND ND ND 1,1,2-Trichloroethane 5 NDNDNDND Trichloroethene (TCE) 10 ND ND ND ND Trichlorofluoromethane 1000 ND ND ND ND Vinyl Chloride 1 NDNDNDND m/p-Xylene 1000 ND ND ND ND o-Xylene 1000 ND ND ND ND TPH-g 5000 ND ND ND ND Isobutane (Tracer Gas) 1000 ND ND ND ND Note: ND = Below Listed Reporting Limit Inst. ID: Detector: SAMPLE ID 1667 Cross Bridge Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-62352369 Rutland Place, Thousand Oaks, CA 91362 • Toll Free (877) SOIL GAS (764-5427) • (818) 734-6230 • Fax (818) 734-6235 OPTIMAL TECHNOLOGYSpecializing in Environmental Field Services Optimal Technology LH.indd 1 8/26/2008 2:46:55 PM CHAIN OF CUSTODY FORM Page: 1 of 1 Site Name/Number NE Corner of Panama Lane & Buena Vista Rd.,PO# / Project Ref# Site Address Bakersfield, CA Company Name Contact Person(s): Phone#Email: Comments: TESTS REQUIRED (please mark with an "X") Sample Sampling Date Time Soil Gas Soil Gas Soil Gas Identification Device Collected Collected Mod 8260B Mod 8021B Mod 8015 BLANK-1 Syringe 7/6/23 8:05 AM x SV-1-5 Syringe 7/6/23 8:26 AM x SV-1-10 Syringe 7/6/23 8:45 AM x SV-2-5 Syringe 7/6/23 9:06 AM x SV-2-10 Syringe 7/6/23 9:28 AM x SV-3-5 Syringe 7/6/23 9:50 AM x SV-3-10 Syringe 7/6/23 10:18 AM x SV-4-5 Syringe 7/6/23 10:40 AM x SV-4-10 Syringe 7/6/23 11:06 AM x SV-4-10 Dup Syringe 7/6/23 11:06 AM x SV-5-5 Syringe 7/6/23 11:35 AM x SV-5-10 Syringe 7/6/23 11:54 AM x Collected & Tested by: Notes