Assessment of Potential Enviromental Exposure Risks for Water Distribution System Otay Ranch Village III Chula Vista, California []\ GeoKinetics Geotechnical & Environmental Engineers Prepared by GeoKinetics 77 Bunsen Irvine, CA 92618 Tel 949.502.5353, Fax 949.502.5354 December 13, 2017 Prepared for HOMEFED BROOKFIELD OTAY, LLC HOMEFED SPIC OTAY, LLC HOMEFED SH OTAY LLC 1.0 2.0 Introduction: GeoKinetics has been retained by HomeFed SPIC Otay LLC, HomeFed Brookfield Otay LLC, and HomeFed SH Otay LLC to evaluate potential impacts to the potable and reclaimed water distribution system from Volatile Organic Compounds (VOCs) that are present in the subsurface at the Otay Ranch Village development in Chula Vista, California. The general site location is shown in Figure 1 while a recent aerial photograph of the project area is provided as Figure 2. Permeation of plastic pipe and/or fittings and gaskets by organic solvents has occurred in some instances in the past where very high concentrations of solvents were present in soil or groundwater that was in direct contact with water distribution or service lines. In this submittal, we have identified the circumstances under which pipe or pipe components could potentially be impacted by organic solvents and compared those conditions to what exists at the subject development. As will be discussed in the subsequent sections of this report, no potential exists for the water distribution system to be impacted by VOCs or methane at the subject development based upon the available data. Water Distribution System: The project plans indicate there will be two primary water mains and an associated distribution system that will service the development. The general configurations of these systems are described below: Potable Water Main: This line will consist of a 16" diameter cement? mortar lined, taped, and coated steel pipe within the Heritage Road right?of-way from Main Street to Station 21 +78. From Station 21 +78 to approximately Station 56+00, the main will consist of 16" diameter Class 235 PVC pipe. The plans show and 12" diameter distribution lines extending from the 16" PVC water main at various locations. Reclaimed Water Main: This line will consist of an 8" diameter steel pipe within the Heritage Road right-of-way from Main Street to Station 22+?l 5 and an 8" diameter Class 305 PVC pipe with Styrene?Butadiene?Rubber (SBR) gasketed joints from that point to station 56+00. Distribution System: Water distribution systems will extend throughout the development from the water mains. The primary distribution piping will consist of and 12? diameter PVC pipe. Ancillary components Assessment of Water Distribution System Exposure Risk Otay Ranch Village Development - Chula Vista, California December 13, 2017 3.0 associated with the distribution system include gate valves, hydrants, blow- off valves, air?valves, and copper services. The utility construction plans and specifications for the subject development indicate the following materials may be used on various water system components: 0 PVC pipe with ductile iron fittings and valves; 0 Copper pipe, brass saddles and valves; 0 Nylon bushings and dielectric couplings; SBR, neoprene, or ethylene propylene diene monomer (EPDM) pipe end seals; 0 Butyl rubber gaskets; PolyTetraFluoroEthylene (PTFE) flange gaskets; Polyethylene encasement sleeves for corrosion protection of ductile iron; 0 PVC utility tape for corrosion protection; 0 Nitrile-butadiene-rubber (NBR or Buna-N) gaskets, o-rings, and valve seats; and EPDM valve seats, valve packings, o-rings, and seals. The potential for these components to be impacted by the maximum concentrations of the compounds that have been detected in the subsurface at the subject development is evaluated in this submittal. Site Conditions: The northern margin of the Otay Ranch Village Ill development is located approximately 800 feet from the southern margin of the Otay Landfill (Figures 1 2). Generally low levels of methane gas and VOCs have been detected in the subsurface at the Otay Ranch Village development. The nearby page 2 Assessment of Water Distribution System Exposure Risk Otay Ranch Village Development - Chula Vista, California December 13, 2017 landfill represents a potential source of these compounds. Extensive testing was recently performed by TRC Consultants on behalf of the master developer (HomeFed Village Master, LLC) to establish the nature, extent, and concentrations of methane and VOCs in the subsurface at the site (TRC, August 2017). A total of 40 gas probe installations were completed and sampled to document methane gas and soil vapor VOC levels across the site. The gas probes locations are shown in Figure 3. As indicated, the majority of the installations had multiple sampling tips at varying depths. A total of 99 soil gas samples were collected and analyzed from the 75 sampling tips. The results of site assessment activities are discussed below. 3.1 Soil Gas VOCs: The soil gas VOC testing results are summarized in Table 1. This data has been extracted from Table 5 of Human Health Vapor Risk Assessment (TRC, 2017). The soil gas samples collected by TRC were analyzed by a state?certified laboratory in accordance with EPA method 82608. A total of 66 individual VOCs were scanned for in each sample using that protocol. Of those 66 VOCs, 42 were not detected in any of the samples. The results for the remaining 24 VOCs that were detected in at least one soil gas sample are summarized in Table 1. It should be noted that VOC concentrations in Table 1 of this submittal are expressed in micro-grams per liter while the units in original table are micro-grams per cubic meter (pg/m3). One pg/L is equal to 1,000 ,ug/ms. For reference purposes, 1 pg/L is equivalent to 1 part?per?billion for a compound with a specific gravity of 1.0, such as water. One yg/L is the equivalent of 50 drops of water in an olympic size swimming pool. The 24 individual VOCs identified in the soil gas samples were detected at very low concentrations. The highest concentration at which an individual VOC was detected was 7.2 ,ug/L for total xylenes in gas probe SGP-1 at a depth of 10 feet bgs. The highest combined total for all VOCs at a particular sampling location was 15.2 yg/L at 10 feet in SGP-1. The average total soil vapor VOC level for the 99 samples that were collected is 2.2 ,ug/L. There were only four VOCs that were detected at any location at a concentration in excess of 1 ,ug/L. Those are total xylenes at 7.2 pg/L, toluene at 3.0 lug/L, at 1.8 pg/L, and at 1.4 page 3 Assessment of Water Distribution System Exposure Risk Otay Ranch Village Development - Chula Vista, California December 13, 2017 pg/L. Each of these compounds is a component of gasoline (Le. a fuel hydrocarbon). The statistical distribution (probability of exceedance) of the soil total VOC vapor level based on the measured values is provided in Figure 4. It is significant to note that elevated soil gas pressures were not detected in any of the gas probe installations. The spacial distribution of the total soil VOC vapor levels measured at depths of 5 feet and >5 feet are shown in Figures 5 and 6, respectively. As shown, the testing results indicate a bias for higher soil vapor VOC levels in the western portion of the development which is closer to the Otay Landfill. The VOCs that have been detected at the site consist predominately of a combination of fuel hydrocarbons (benzene, toluene, xylene, etc.) and chlorinated solvents (tetrachloroethylene, trichloroethylene, etc). All of the VOC vapor levels are low and therefore suggestive of a relatively distant and/or dilute source as opposed to an on-site release of gasoline or solvent(s). The fact that the VOCs are widely distributed across the site is more suggestive of the former source scenario. The relatively diverse types of VOCs that have been detected are consistent with typical landfill soil gas signatures. The nearby Otay Landfill represents the most likely source of the low VOC vapor levels that have been detected at the site. At very high concentrations, some solvents can permeate PVC pipe and other plastic materials. However, as will be discussed in Section 4 of this submittal, the very low concentrations of VOCs that have been measured at the site are orders of magnitude below the threshold where there could be any impact to the potable and recycled water lines or their associated components. 3.2 Methane Gas: The presence of methane gas in the subsurface is common within engineered fills which typically contain trace amounts of organic material such as grass, leaves, wood, etc. Biogenic methane is generated by the bacteriological digestion, or biodegradation, of that organic matter under anaerobic conditions page 4 Assessment of Water Distribution System Exposure Risk Otay Ranch Village Development - Chula Vista, California December 13, 2017 (Tofani, 2002). It has been our experience that elevated levels of methane gas occur in the majority of engineered fills that are greater than approximately 10 feet in depth. A study undertaken by the County of San Diego in the early 2000?s reached this same conclusion (Tofani, 2002; Sepich, 2014). High concentrations of methane gas in the subsurface were discovered at the 48 Ranch development site in San Diego County during grading activities in 1999. The source of the methane was not known and the County was concerned it could present safety risks with respect to the ongoing development. The County assembled a group of technical experts to advise it on how to address the issue. After evaluating the available data, GeoKinetics and other consultants concluded the methane likely originated from organic matter entrained within the fill. To further evaluate that as the potential source, the County imposed an ordinance in 2001 that required subsurface probes to be installed and sampled on every new mass-graded residential lot following grading for the purpose of screening for methane gas. Probes were installed, and monitoring was performed, on thousands of residential lots over the next several years. That data indicated elevated levels of methane gas were common at lots where the fill thickness exceeded 10 feet, and conversely, it indicated a low probability of elevated methane levels in shallower fills. Methane gas was measured at concentrations well in excess of 100,000 in some of the deeper fills. The methane gas was not found to be at elevated pressures. Due to the source of the gas (biogenic), the limited volume of gas that was present, and the absence of significant pressure, the County concluded the presence of the methane within the fill soils presented no significant risk and repealed the ordinance that required testing in April of 2005 without imposing mitigation requirements. The locations and concentrations of methane measured by TRC at a depth of 5 feet are shown in Figure 7 while those measured at depths in excess of 5 feet are shown in Figure 8. As indicated, the maximum recorded methane concentration was 38,000 in gas probe SGP-T near the west southwest corner of the development. The vast majority of the reported methane concentrations are very low and consistent with nominal background levels for engineered page 5 Assessment of Water Distribution System Exposure Risk Otay Ranch Village Development - Chula Vista, California December 13, 2017 fill. The methane concentrations measured near the west southwest corner of the site are typically higher than those measured in the other portions of the site. This distribution is generally consistent with that of the VOC vapors discussed previously and suggests the nearby Otay Landfill has likely contributed to the elevated methane levels. The possibility that methane from the landfill also represents a component of the generally lower concentrations of combustible gas that have been measured in other portions of the Otay Ranch Village development cannot be precluded. That contribution would be consistent with the trace VOC levels that have been measured within the development as discussed above. Methane gas is not toxic and it is not reactive with any of the materials that may be used for the water piping systems. As such, the presence of methane gas at the site will not impact the performance of those utilities. Methane is potentially explosive in the presence of oxygen at concentrations in excess of 55,000 ppm. This concentration is referred to as the Lower Explosive Level (LEL) for methane. 3.3 Groundwater: The regional groundwater table is reported to occur at a depth of 100 feet or more below the ground surface in the project area. TRC (August 2017) noted that perched groundwater was encountered immediately west of Heritage Road during the installation of the storm drain between Stations 19+87 and 20+?l7. The perched groundwater was reportedly encountered at depths ranging from approximately 15 to 17 feet at that location. The plans call for the water mains that will service the subject development to be installed at a depth of approximately 5 feet immediately east of Heritage Road in that area. As such they are not expected to be exposed to perched groundwater. Perched groundwater was not encountered in any of the other utility or exploratory excavations within the development. As will be discussed in the subsequent sections of this submittal, the pipe materials that are proposed for the water mains would be expected to perform in an acceptable manner even if they were immersed in severely contaminated groundwater (Mac, 2008). page 6 Assessment of Water Distribution System Exposure Risk Otay Ranch Village Development - Chula Vista, California 4.0 Permeation of VOCs: Permeation refers to the movement of chemicals through a pipe wall, gasket, or other component. Permeation of VOCs became a concern during the 1970?s and it has been extensively studied during the subsequent decades. The potential for permeation of PVC pipe and pipe gaskets is discussed separately in the following sections. 4.1 PVC Pipe: PVC pipe has been found to be an effective barrier to VOCs in all but the most extreme circumstances (Mac, 2008; AWWA, 2008; et in one study, PVC pipe was immersed in gasoline for more than two years without adverse effects (AWWA, 2008). The available data indicates PVC pipe can be used indefinitely in soil or groundwater contaminated with gasoline or other fuel hydrocarbons regardless of the level of contamination (AWWA, 2007; Mac, 2008). PVC pipe is essentially impervious to VOCs at the concentrations that are typically encountered at even severely contaminated sites. Measurement of the diffusion rates for VOCs through PVC pipe indicate that under normal circumstances, hundreds to thousands of years would be required for even minute amounts of VOCs to penetrate the pipe wall (Bromhead, 1997; Selleck, 1991). In order for permeation of PVC pipe to occur, the nature of the plastic has to be altered. That can occur if PVC is exposed to extremely high (near pure) concentrations of certain solvents. Under those conditions softening and swelling of the PVC can occur Selleck 1991; Bromhead, 1997; Mac, 2008). It has been shown that this softening and swelling can progress relatively rapidly from the outer wall to the inner wall of a pipe along a well defined interface (Agelet, 2007). However, in order for this process to occur, the PVC must be exposed to unusually high concentrations of one or more aggressive solvents. For example, pure benzene and toluene have been shown to degrade and penetrate PVC pipe within a matter 0f days to weeks. However, as noted above, studies have shown that PVC pipe can be immersed in gasoline containing those solvents for an indefinite period of time without impact. The typical concentrations at which benzene and toluene are present in gasoline are on the order of 15,000,000 pg/L and 70,000,000 ,ug/L, respectively. Yet these solvent concentrations are not sufficient to cause softening, swelling, or permeation of PVC pipe. GeoKinetics has performed long term solvent diffusion tests on PVC and other membrane materials at concentrations of up to 175,000 pg/ without page 7 December 13, 2017 Assessment of Water Distribution System Exposure Risk Otay Ranch Village Development - Chula Vista, California December 13, 2017 any deterioration or degradation of those materials (Tofani, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2016). The available data has established that in order for permeation of PVC to occur, the concentration of the solvent must be greater than 25% of its water solubility for pipe exposed to contaminated groundwater, or greater than 25% of its vapor saturation level for pipe exposed to contaminated soil above the groundwater table (Vonk, 1985; Bromhead, 1997; Mac, 2008). The relative saturation of the solvent in an aqueous solution, or in vapor phase, is referred to as the "activity" of the solvent. The vapor phase activities of the five solvents that were detected at the highest concentrations at the site are shown in Table 2. These five solvents are all fuel hydrocarbons. The activity of a common chlorinated solvent that was detected at the site (tetrachloroethylene or PCE) is also shown in Table 2 for reference purposes. Finally, the approximate equivalent activity for the combined maximum solvent vapor concentration that was measured at the site in a single sample (15.2 pg/L in SGP-1 10? bgs) is shown on the bottom row of Table 2. As indicated, in each case a vapor concentration of 1.0 106/1g/L, or greater, would be required in order for the potential for permeation of the PVC to exist. The VOC vapor levels measured at the site are many orders of magnitude below this threshold. For each VOC listed in Table 2, the ratio between the 0.25 activity threshold permeation concentration and the maximum concentration at which that VOC was detected at the site has been represented as a factor of safety. Permeation would not be expected to occur at factors of safety in excess of unity 1.0). As shown in Table 2, the calculated factors of safety range from approximately 80,000 for the combined maximum total VOC concentration to 153,000+ for the individual maximum VOC concentrations. The ratios between the minimum threshold VOC vapor levels for permeation to occur and the maximum VOC vapor levels measured at the site are also shown graphically in Figure 9. It should be noted that a logarithmic scale has been utilized for the vapor concentrations on the Y?Axis of this figure since the bars representing the maximum measured vapor concentrations would otherwise be too small to be visible. The values shown in Table 2 and Figure 9 indicate that permeation of page 8 Assessment of Water Distribution System Exposure Risk Otay Ranch Village Development - Chula Vista, California December 13, 2017 PVC pipe could not possibly occur at the very low VOC vapor concentrations that have been measured at the site. Without permeation of the PVC pipe, there will be no degradation or damage to the pipe, or detectible impacts to the quality of the water that is conveyed by the pipe. It should be noted that the 0.25 activity value that is referenced as the permeation threshold is relatively conservative. One series of tests indicated that PVC pipe was not permeated by benzene or toluene at 0.60 activity concentrations (Mao, 2008). Other studies concluded that activities of 0.5 or greater were necessary for permeation of PVC pipe to occur (Baren, 1985). Permeation of PVC pipe has been demonstrated at lower activities where a mixture of solvents was present but in no case has permeation occurred at organic vapor levels less than several hundred thousand pg/L (EPA, 2002). Similarly, measurable permeation of ductile iron, copper, and/or bronze pipe or pipe fittings at the very low soil vapor VOC levels that have been detected will not occur (AWWA, 2007). 4.2 Gaskets Seals: As with plastic pipe, a considerable amount of research and testing has been done over the past 30 years to evaluate the potential for VOCs to penetrate or otherwise impact rubber gaskets and seals. Incidents involving the permeation of hydrocarbons through gaskets are very rare (Bromhead, 1997). The EPA concluded that there were two reasons for that (EPA, 2002). First, the exposed circumferential area associated with the gasket is much smaller than that of the pipe. Second, the gaskets are usually installed in areas where there is continuous flow such that the permeation rate would be too low to impact the water quality. in addition, as discussed for PVC above, unusually high concentrations of solvents must be present for permeation to occur. AWWA, et al. (2007) performed permeation tests and concluded that water mains equipped with SBR gaskets could be used at any level of gasoline contamination with minimal average flow without exceeding drinking water Maximum Contaminant Levels (MCLs). Mao (2008) performed similar testing of pipes with SBR and NBR gaskets and found no permeation occurred with gasoline-saturated water. More recently, Cheng, et al. (2012) found no significant permeation of SBR gaskets by water contaminated with gasoline at a concentration of 30,000 page 9 Assessment of Water Distribution System Exposure Risk Otay Ranch Village Development - Chula Vista, California December 13, 2017 5.0 lug/L and no permeation of NBR gaskets by water that was saturated with gasoline (:100,000 pg/L). As was the case for PVC pipe discussed previously, the maximum concentrations at which the soil gas VOCs have been detected at the site are many thousands of times below the threshold where measurable permeation of gaskets or seals could occur. As noted previously, the VOC levels that have been measured at the subject property are very low. Any of the gasket and seal materials identified previously in Section 2 of this submittal would perform in an acceptable manner indefinitely at those VOC levels (AWWA, 2008; Tofani, 2004 et Similarly, the very low soil vapor VOC levels that have been detected will not have an impact on the polyethylene plastic protective coatings that are often used for corrosion protection of metal pipe and fittings (AWWA, 2007; Tofani, 2008 et Worker Safety: No special provisions or precautionary measures are anticipated to be necessary to ensure the safety of workers installing, operating, and maintaining the water distribution system improvements based on the testing results described herein. Unpressurized biogenic methane presents no potential issues at concentrations below its LEL. Methane concentrations in excess of the LEL have not been recorded in the subsurface at the subject development. However, as described previously, subsurface methane concentrations in excess of the LEL commonly occur in areas of engineered fills. As such, we suggest that routine precautionary measures be taken at all active construction sites. These measures should include monitoring open excavations for the presence of combustible gas. The greatest potential for methane accumulation typically occurs in trenches or other excavations that are covered overnight. Covered excavations should be monitored, and ventilated if necessary, before potential ignition sources are introduced to the area. If personnel are to be working within trenches or similar excavations, those workers should be equipped with personal gas detectors to monitor combustible gas and oxygen levels. As indicated in Table 3, the maximum concentrations of VOCs measured in the subsurface are well below OSHA 8-hour Permissible Exposure Limits (PELs). As such, the measured VOC levels do not appear to present any significant short term exposure risks to workers. page 10 Assessment of Water Distribution?System Exposure Risk Otay Ranch Village Development - Chula Vista, California December 13, 2017 6.0 Summary Conclusions: Low concentrations of twenty-four different VOCs have been detected in soil gas samples collected at the Otay Ranch Village development. The highest concentration at which any individual VOC has been detected is 7.2 ,ug/L for total xylene and the highest combined total for all VOCs at an particular sampling location is 15.2 ,ug/L. Permeation of VOCs through PVC pipe and gaskets has been shown to occur when those components are exposed to very high concentrations of solvents. The minimum vapor concentration required for an aggressive solvent to permeate PVC is on the order of 1,000,000 pg/L. As such, the concentrations at which the V003 have been detected in the subsurface at the site are much too low for those VOCs to have any impact on the water distribution systems. Very high factors of safety exist with respect to this issue. At the low concentrations at which the V005 have been detected there will be no degradation or damage to the pipe materials, or detectible impacts to the quality of the water that is conveyed by the pipe. The water distribution systems can be installed and operated indefinitely, as proposed, with confidence that those systems will not be impacted by the very low levels of VOC vapors that have been detected at the site. No special provisions or precautionary measures are anticipated to be necessary to ensure the safety of workers installing, operating, and maintaining the water distribution system improvements based on the testing results described herein. 7.0 Closing: We hope the information contained in this submittal is helpful with respect to assessing the potential exposure risks to the water distribution systems at the subject development. Please feel free to direct any questions or comments regarding the contents of this report to the undersigned. Sincerely, GEOKINETICS, INC. Glenn D. Tofani, Geoffrey D. Stokes, r/j Principal Engineer Senior Geologist I, . ENGENEEPJNG l- I ?Tn/r ,3 .9. .7 No. GE 2493 I Attachments Exn. 06-30?19 page 1 'l 10. 11. References Prediction of Organic Chemical Permeation Through PVC Pipe by AR. Barens published by AWWA, 1985. Permeation of Organic Compounds Through Pipe Materials by MW. Vonk, 1985. Analyzing the Permeation of Organic Chemicals Through Plastic Pipes by Robert Selleck et al., published by American Water Works Association, July 1991. The Effect of Soils on the Permeation of Plastic Pipes by Organic Chemicals by Thomas Holsen et al., published by American Water Works Association, November 1991. Permeation of Benzene, Trichloroethene and Tetrachloroethene through Plastic Pipes by J. Bromhead, December 1997. Durability and PERformance of Gravity Pipes: A State?of?the?Art Literature Review by Jack Zhao et al., published by National Research Council of Canada, August 1998. How Hose Materials Affect Gas published in Welding Journal, July 1999. Permeation and Leaching published by American Water Works Association and US. EPA, August 2001. PVC Pipe-Design and Installation: Manual of Water Supply Practices published by American Water Works Association, 2002. The MTRANS Methane Gas Migration Model - Methane Geotechnical Working Group prepared for Building Industry Association by Glenn Tofani, Hassan Amini, Gordon Alexander, Marlaigne Hudnall, and Brian Villalobas, June 2002. Potential Water Quality Deterioration of Drinking Water Caused by Leakage of Organic Compounds from Materials in Contact with the Water by Lars J. Hem, proceedings 20th NoDig conference in Copenhagen on May 28-31, 2002. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. Risk Analysis for Water Quality Deterioration in Distribution Networks by R. Sadiq et al., published by NRC of Canada, June 2004. Results of Solvent Diffusion Tests on Liquid BootH Membranes by Glenn Tofani, November 2004. Results of Benzene Diffusion Tests for Liquid Bootq Membranes by Glenn Tofani, October 2005. Modeling Benzene Permeation Through Drinking Water High Density Polyethylene (HDPE) Pipes by Feng Mac et al., published in Journal of Water and Health, 2005. Impact of Polymeric Plumbing Materials on Drinking Water Quality and Aesthetics, thesis submitted to the faculty of the Virginia Polytechnic Institute and State University by Timothy Heim, April 2006. Drinking Water Distribution Systems: Assessing and Reducing Risks published by National Research Council, December 2006. Lateral Gas Permeability Testing for Ultrashield G-1000 Geofabric by Glenn Tofani, December 2006. Transmission of Methane Gas and VOC Vapors Through Membranes by Glenn Tofani, February 2007. Permeation Studies of PVC Pipes with Near Infrared Spectroscopy by Lidia Esteve Agelet et al., published in Journal of Near Infrared Spectroscopy, October 2007. Impact of Hydrocarbons on Pipes and Pipe Gaskets published by American Water Works Association Research Foundation, winter 2007/2008. Results of Chemical Exposure Testing for Cetco Waterproofing Materials by Glenn Tofani, March 2008. Permeation of Hydrocarbons through Polyvinyl Chloride (PVC) and Polyethylene (PE) Pipes and Pipe Gaskets, a dissertation submitted to the graduate faculty at Iowa State University by Feng Mac, 2008. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. Design Guidelines for Pipelines Crossing Contaminated Areas published Washington Suburban Sanitary Commission, 2008. Chemical Compatibility of Liquid Boot? Membranes With Respect to Vapor Barrier Applications by Glenn Tofani, April 2008. Estimation of Vapor Migration Rates to Building Interiors by Glenn Tofani, et al. presented at the Sixth International Conference on Remediation of Chlorinated and Recalcitrant Compounds, May 2008. Common questions and Answers Regarding the use of Sub-Slab Membranes for VOC Mitigation by Glenn Tofani, January 2009. Results of Diffusion Tests on Polyethylene and Liquid Boot? Membranes by Glenn Tofani for Dow Chemical Ltd., March 2009. Permeation of Organic Contaminants Through PVC Pipes by Feng Mao et aI., published by American Water Works Association, May 2009. Chemical Compatibility of Liquid Boot? Membranes With Respect to Vapor Barrier Applications by Glenn Tofani, May 2009. Plastic Pipe Institute Comments on Permeation of Water Pipes and on the American Water Works Association-RF Report on Hydrocarbons, March 2009. Results of Solvent Diffusion Tests on Membranes by Glenn Tofani, December 2009. Performance Monitoring of VOC Mitigation Systems by Glenn Tofani and Kevin Lea presented at the Seventh International Conference on Remediation of Chlorinated and Recalcitrant Compounds, May 2010. Improving Safety of Crude Oil and Regional Water System Pipeline Crossings by Delvin E. DeBoer, November 2010. Results of Solvent Diffusion Tests for GeoSeal Membranes by Glenn Tofani, August 201 1 . 3645. Long?Term Study of Migration of Volatiles Organic Compounds from Cross?linked Polyethylene (PEX) Pipes and Effects on Drinking Water Quality by Vidar Lund et al., published in Journal of Water and Health, September 2011. Permeation of Gasoline Through Ductile Iron Pipe Gaskets in Water Mains by Chu-Lin Cheng et al., published by American Water Works Association, April 2012. Assessment and Calculations of BTEX Permeation Through HDPE Water Pipe by Dae Hyen Koo, July 2012. A Rational Approach to Methane Hazard Assessment by John Sepich and Stephen Marsh, 2014. Results of Solvent Diffusion Tests for GeoSea/ Epro System Membranes by Glenn Tofani, August 2016. Otay Ranch Village 3 Heritage Road Utility Plans by Imperial Pipe for Western Water Works Supply Company dated November 22, 2016. Otay Ranch Village Potable and Reclaimed Water Construction Materials Submittal by Cass Construction Inc. dated December 21, 2016. Otay Ranch Village Potable and Reclaimed Water Construction Materials Submittal by Cass Construction Inc. dated January 5, 2017. Otay Ranch Village - Heritage Road Improvement Plans by Hunsaker Associates dated August 29, 2017. Estimation of Permeability of Organic Compounds Through PVC Pipes by Bing-Hsien Wang et al., presented at 2017 Asia-Pacific Engineering and Technology Conference, 2017. Table 1 - Summary of Soil Gas VOC Measurements for Otay Ranch Village III Development Probe Location Lot 42 Lot 42 Lot 51 Lot 51 Lot 60 Lot 60 Lot 73 Lot 73 Lot 94 Lot 94 Lot 101 Lot 101 Lot 108 Lot 108 Lot 126 Lot 126 Lot 196 Lot 196 Lot 202 Lot 202 Lot 211 Lot 211 Lot 223 Lot 223 Lot 253 Lot 253 Lot 324 Lot 324 Lot 335 Lot 335 Lot 342 Lot 342 Lot 352 Lot 352 Lot 699 Lot 699 Lot 711 Lot 711 Lot 735 Lot 735 Lot 745 Lot 760 Lot 760 Lot 769 Lot 769 Lot 824 Lot 825 Lot 825 Lot 816 Lot 817 Lot 817 Lot 817 1,1‐Dichlor Probe ID (ug/L) SGP‐42‐5 SGP‐42‐25 SGP‐51‐5 SGP‐51‐25 SGP‐60‐5 SGP‐60‐25 SGP‐73‐5 SGP‐73‐25 SGP‐94‐5 SGP‐94‐25 SGP‐101‐5 SGP‐101‐25 SGP‐108‐5 SGP‐108‐25 SGP‐126‐5 SGP‐126‐25 SGP‐196‐5 SGP‐196‐30 SGP‐202‐5 SGP‐202‐25 SGP‐211‐5 SGP‐211‐25 SGP‐223‐5 SGP‐223‐25 SGP‐253‐5 SGP‐253‐22 SGP‐324‐5 SGP‐324‐25 SGP‐335‐5 SGP‐335‐30 SGP‐342‐5 SGP‐342‐32 SGP‐352‐5 SGP‐352‐25 SGP‐699‐5 SGP‐699‐25 SGP‐711‐5 SGP‐711‐8 SGP‐735‐5 SGP‐735‐15 SGP‐745‐5 SGP‐760‐5 SGP‐760‐20 SGP‐769‐5 SGP‐769‐15 SGP‐824‐5 SGP‐825‐5 SGP‐825‐12 SGP‐816‐3 SGP‐817‐5 SGP‐817‐5 SGP‐817‐10 1,2,4‐ 1,3,5‐ Probe Depth Trimethyl‐ Trimethyl‐ o‐ ethane (fbg) benzene benzene 5 25 5 25 5 25 5 25 5 25 5 25 5 25 5 25 5 30 5 25 5 25 5 25 5 22 5 25 5 30 5 32 5 25 5 25 5 8 5 15 5 5 20 5 15 5 5 12 3 5 5 10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 (ug/L) (ug/L) 0.20 0.28 0.19 0.08 0.80 0.16 0.12 0.42 0.06 0.05 0.15 0.10 0.10 0.04 0.48 0.26 0.05 0.14 0.07 0.09 0.09 0.12 0.28 0.00 0.41 0.04 0.11 0.00 0.26 0.37 0.08 0.01 0.26 0.24 0.45 0.28 0.01 0.00 0.01 0.01 0.22 0.06 0.07 0.07 0.03 0.16 0.14 0.08 0.07 0.13 0.11 0.08 0.08 0.11 0.08 0.04 0.30 0.06 0.00 0.17 0.02 0.02 0.07 0.05 0.04 0.01 0.24 0.12 0.01 0.07 0.02 0.04 0.04 0.05 0.10 0.00 0.19 0.02 0.06 0.00 0.08 0.15 0.03 0.00 0.07 0.09 0.21 0.14 0.00 0.00 0.00 0.00 0.08 0.02 0.03 0.03 0.01 0.06 0.00 0.00 0.00 0.00 0.00 0.00 Benzene (ug/L) Bromo‐ dichloro‐ methane (ug/L) Carbon disulfide (ug/L) Chlorofor m (ug/L) cis‐1,2‐ Dichloro‐ ethene (ug/L) Dibromo‐ chloro‐ methane (ug/L) Dichloro‐ difluoro‐ methane (ug/L) Ethyl‐ benzene (ug/L) Isopropyl‐ benzene (ug/L) 0.02 0.04 0.06 0.02 0.03 0.00 0.01 0.07 0.02 0.03 0.03 0.03 0.00 0.01 0.10 0.13 0.00 0.04 0.00 0.02 0.00 0.05 0.01 0.02 0.06 0.01 0.03 0.01 0.04 0.14 0.02 0.00 0.02 0.03 0.10 0.09 0.00 0.00 0.00 0.00 0.04 0.00 0.02 0.02 0.00 0.01 0.01 0.01 0.02 0.01 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.29 0.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.16 0.00 0.00 0.00 0.00 0.00 0.14 0.00 0.00 0.00 0.00 0.00 0.06 0.00 0.05 0.00 0.16 0.00 0.17 0.00 0.00 0.09 0.09 0.00 0.00 0.00 0.07 0.00 0.00 0.00 0.00 0.07 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.06 0.03 0.00 0.00 0.43 0.23 0.00 0.00 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.19 0.07 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.14 0.17 0.21 0.06 0.35 0.00 0.00 0.37 0.04 0.03 0.09 0.07 0.05 0.01 0.24 0.14 0.01 0.18 0.03 0.09 0.07 0.16 0.05 0.00 0.18 0.02 0.16 0.00 0.11 0.43 0.07 0.00 0.07 0.16 0.21 0.15 0.00 0.00 0.00 0.00 0.19 0.04 0.10 0.06 0.02 0.04 0.00 0.00 0.00 0.00 0.04 0.04 0.00 0.01 0.01 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.03 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Page 1 of 2 meta‐ and Naphthale para‐ ne Xylenes (ug/L) (ug/L) 0.58 0.72 0.76 0.22 1.20 0.13 0.10 1.30 0.16 0.13 0.39 0.28 0.19 0.05 0.97 0.59 0.05 0.64 0.12 0.33 0.29 0.56 0.34 0.08 0.83 0.06 0.50 0.07 0.46 1.40 0.24 0.02 0.32 0.59 0.90 0.62 0.00 0.00 0.02 0.00 0.76 0.18 0.38 0.24 0.07 0.19 0.09 0.08 0.09 0.19 0.22 0.17 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.02 0.00 0.02 n‐Butyl‐ benzene (ug/L) n‐Propyl‐ benzene (ug/L) ortho‐ Xylene (ug/L) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.05 0.04 0.02 0.13 0.00 0.00 0.11 0.01 0.00 0.03 0.02 0.02 0.00 0.08 0.04 0.00 0.03 0.00 0.00 0.02 0.03 0.04 0.00 0.07 0.00 0.00 0.00 0.00 0.08 0.02 0.00 0.00 0.04 0.08 0.05 0.00 0.00 0.00 0.00 0.04 0.01 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.20 0.25 0.22 0.07 0.47 0.05 0.04 0.38 0.05 0.03 0.13 0.09 0.07 0.02 0.29 0.16 0.02 0.18 0.04 0.11 0.09 0.16 0.16 0.00 0.28 0.02 0.12 0.00 0.16 0.41 0.08 0.00 0.14 0.22 0.27 0.17 0.00 0.00 0.00 0.00 0.46 0.05 0.08 0.07 0.02 0.09 0.00 0.00 0.00 0.09 0.09 0.07 p‐Isopropy sec‐Butyl‐ l‐ toluene benzene (ug/L) (ug/L) 0.02 0.03 0.03 0.05 0.04 0.00 0.00 0.07 0.00 0.00 0.01 0.01 0.01 0.00 0.02 0.00 0.01 0.02 0.00 0.00 0.01 0.03 0.07 0.00 0.01 0.00 0.00 0.00 0.00 0.08 0.02 0.00 0.00 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.03 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Styrene (ug/L) Tetrachlor o‐ ethene (ug/L) Toluene (ug/L) Trichloro‐ ethene (ug/L) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.37 0.43 0.66 0.13 0.38 0.18 0.00 0.85 0.12 0.10 0.27 0.18 0.10 0.03 0.70 0.58 0.03 0.52 0.06 0.21 0.15 0.48 0.00 0.00 0.47 0.04 0.28 0.00 0.19 0.99 0.16 0.01 0.12 0.24 0.65 0.49 0.00 0.00 0.01 0.01 0.47 0.09 0.30 0.16 0.05 0.09 0.00 0.00 0.00 0.09 0.10 0.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Trichloro‐ Total VOCs fluoro‐ (ug/L) methane (ug/L) 0.02 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.67 2.11 2.27 0.91 3.70 0.58 0.27 3.76 0.48 0.53 1.18 0.83 0.58 0.18 3.17 2.09 0.18 1.88 0.34 1.05 0.76 1.81 1.11 0.13 2.62 0.30 2.17 0.49 1.30 4.12 0.72 0.05 1.00 1.62 2.99 2.02 0.01 0.00 0.04 0.02 2.29 0.45 1.01 0.67 0.21 0.64 0.27 0.18 0.23 0.53 0.58 0.51 Table 1 - Summary of Soil Gas VOC Measurements for Otay Ranch Village III Development Probe Location 1,1‐Dichlor 1,2,4‐ 1,3,5‐ Probe Depth Trimethyl‐ Trimethyl‐ o‐ ethane (fbg) benzene benzene Probe ID (ug/L) Benzene (ug/L) Bromo‐ dichloro‐ methane (ug/L) Carbon disulfide (ug/L) Chlorofor m (ug/L) cis‐1,2‐ Dichloro‐ ethene (ug/L) Dibromo‐ chloro‐ methane (ug/L) Dichloro‐ difluoro‐ methane (ug/L) Ethyl‐ benzene (ug/L) Isopropyl‐ benzene (ug/L) meta‐ and Naphthale para‐ ne Xylenes (ug/L) (ug/L) n‐Butyl‐ benzene (ug/L) n‐Propyl‐ benzene (ug/L) ortho‐ Xylene (ug/L) p‐Isopropy sec‐Butyl‐ l‐ toluene benzene (ug/L) (ug/L) Styrene (ug/L) Tetrachlor o‐ ethene (ug/L) Toluene (ug/L) Trichloro‐ ethene (ug/L) Trichloro‐ Total VOCs fluoro‐ (ug/L) methane (ug/L) (ug/L) (ug/L) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.04 0.00 0.00 0.11 0.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.16 0.15 0.27 0.43 0.74 0.69 0.38 0.61 1.40 1.80 0.41 0.60 0.20 0.25 0.16 0.31 0.85 1.20 0.62 0.89 0.23 0.40 0.02 0.05 0.20 0.32 0.06 0.08 0.06 0.08 0.05 0.00 0.06 0.06 0.32 0.38 0.45 0.37 1.20 0.21 0.82 0.11 0.14 0.28 0.19 0.81 0.61 0.00 0.00 0.10 0.16 0.20 0.18 0.13 0.23 0.66 0.88 0.15 0.19 0.07 0.09 0.06 0.11 0.34 0.46 0.23 0.37 0.08 0.17 0.01 0.02 0.07 0.13 0.02 0.03 0.02 0.03 0.00 0.00 0.00 0.00 0.10 0.15 0.18 0.15 0.45 0.07 0.29 0.04 0.05 0.15 0.07 0.30 0.19 0.03 0.03 0.05 0.05 0.01 0.02 0.18 0.14 0.21 0.14 0.09 0.03 0.10 0.10 0.11 0.10 0.33 0.29 0.08 0.06 0.07 0.14 0.03 0.09 0.10 0.10 0.00 0.00 0.08 0.08 0.01 0.00 0.00 0.01 0.03 0.19 0.20 0.22 0.17 0.04 0.05 0.08 0.08 0.22 0.04 0.06 0.04 0.00 0.00 0.02 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.00 0.00 0.00 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.00 0.12 0.00 0.00 0.00 0.12 0.12 0.11 0.00 0.00 0.00 0.00 0.00 0.11 0.17 0.00 0.00 0.01 0.00 0.10 0.15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.10 0.07 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.07 0.25 0.31 0.15 0.19 0.33 0.49 1.20 1.40 0.35 0.27 0.16 0.22 0.16 0.31 0.77 0.92 0.38 0.55 0.11 0.28 0.02 0.06 0.17 0.26 0.03 0.04 0.04 0.05 0.00 0.00 0.00 0.00 0.16 0.46 0.52 0.49 0.81 0.12 0.27 0.11 0.14 0.43 0.15 0.31 0.18 0.00 0.00 0.02 0.03 0.03 0.03 0.03 0.05 0.11 0.14 0.04 0.03 0.01 0.02 0.01 0.03 0.08 0.10 0.03 0.05 0.01 0.03 0.00 0.00 0.02 0.02 0.00 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.05 0.06 0.05 0.09 0.01 0.03 0.01 0.01 0.04 0.02 0.04 0.02 0.23 0.32 1.00 1.30 0.70 0.83 1.20 1.80 4.80 5.50 1.20 1.10 0.63 0.81 0.59 1.10 2.60 3.10 1.60 2.40 0.47 1.20 0.06 0.20 0.63 0.99 0.12 0.19 0.34 0.37 0.05 0.00 0.06 0.08 0.66 1.60 1.80 1.70 3.10 0.44 1.30 0.40 0.50 1.50 0.59 1.40 0.78 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.02 0.01 0.02 0.02 0.04 0.00 0.02 0.00 0.00 0.00 0.00 0.03 0.04 0.01 0.02 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.00 0.02 0.00 0.00 0.00 0.00 0.02 0.02 0.00 0.00 0.05 0.07 0.10 0.09 0.08 0.13 0.31 0.41 0.09 0.11 0.04 0.05 0.03 0.07 0.21 0.29 0.11 0.16 0.04 0.07 0.00 0.01 0.03 0.05 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.06 0.10 0.13 0.10 0.26 0.04 0.13 0.03 0.03 0.09 0.04 0.14 0.09 0.11 0.12 0.35 0.45 0.29 0.33 0.38 0.54 1.40 1.70 0.36 0.39 0.21 0.26 0.20 0.36 0.73 0.88 0.55 0.77 0.16 0.36 0.02 0.06 0.21 0.31 0.04 0.06 0.09 0.10 0.00 0.00 0.00 0.00 0.22 0.43 0.50 0.46 0.91 0.15 0.47 0.11 0.14 0.42 0.18 0.50 0.31 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.01 0.03 0.05 0.00 0.02 0.00 0.00 0.00 0.00 0.02 0.02 0.01 0.02 0.00 0.01 0.00 0.00 0.01 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.06 0.00 0.01 0.00 0.03 0.00 0.03 0.00 0.00 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02 0.00 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.03 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.01 0.04 0.02 0.00 0.00 0.01 0.02 0.00 0.00 0.26 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.14 0.21 0.72 0.75 0.17 0.29 1.30 1.40 3.00 2.90 0.98 0.51 0.62 0.73 0.66 1.00 2.30 2.60 1.00 1.20 0.33 0.90 0.07 0.27 0.62 0.90 0.07 0.10 0.24 0.27 0.00 0.00 0.00 0.00 0.31 1.60 1.60 1.70 1.90 0.30 0.49 0.41 0.49 1.50 0.36 0.58 0.33 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.72 0.90 2.94 3.76 2.43 2.68 4.03 5.43 13.29 15.18 3.67 3.27 2.08 2.53 1.98 3.39 8.37 9.93 4.62 6.50 1.54 3.59 0.23 0.76 2.13 3.18 0.34 0.51 1.38 1.41 0.21 0.07 0.12 0.15 1.94 5.01 5.47 5.36 9.00 1.39 3.90 1.42 1.70 4.74 1.64 4.19 2.59 Maximum: 0.11 1.80 0.88 0.33 0.29 0.17 0.43 0.02 0.19 0.13 1.40 0.14 5.50 0.05 0.04 0.41 1.70 0.08 0.03 0.05 0.26 3.00 0.05 0.02 15.18 Minimum: 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Average: 0.00 0.28 0.10 0.06 0.00 0.02 0.02 0.00 0.00 0.00 0.19 0.02 0.73 0.00 0.00 0.05 0.23 0.01 0.00 0.00 0.01 0.50 0.00 0.00 2.23 Lot 818 SGP‐818‐5 Lot 818 SGP‐818‐10 Lot 814 SGP‐01‐5 Lot 814 SGP‐01‐5 Lot 814 SGP‐02‐5 Lot 814 SGP‐02‐5 Lot 814 SGP‐03‐5 Lot 814 SGP‐03‐5 Lot 814 SGP‐01‐10 Lot 814 SGP‐01‐10 Lot 814 SGP‐02‐15 Lot 814 SGP‐02‐15 Lot 814 SGP‐03‐15 SGP‐03‐15 Lot 814 Lot 814 SGP‐03‐23 Lot 814 SGP‐03‐23 Lot 814 SGP‐02‐32 Lot 814 SGP‐02‐32 Lot 815 SGP‐04‐5 Lot 815 SGP‐04‐5 Lot 815 SGP‐05‐5 Lot 815 SGP‐05‐5 Lot 815 SGP‐06‐5 Lot 815 SGP‐06‐5 Lot 815 SGP‐07‐5 Lot 815 SGP‐07‐5 Lot 815 SGP‐04‐13 Lot 815 SGP‐04‐13 Lot 815 SGP‐05‐13 Lot 815 SGP‐05‐13 Lot A SGP‐A‐East‐5 Lot A SGP‐A‐East‐5 Lot A SGP‐A‐West‐5 Lot A SGP‐A‐West‐9 Lot A SGP‐A‐East‐20 Lot K SGP‐08‐5 Lot K SGP‐08‐5 Lot K SGP‐09‐5 Lot K SGP‐09‐5 Lot K SGP‐10‐5 Lot K SGP‐10‐5 Lot K SGP‐08‐10 Lot K SGP‐08‐10 Lot K SGP‐09‐10 Lot K SGP‐09‐10 Lot K SGP‐10‐10 Lot K SGP‐10‐10 5 10 5 5 5 5 5 5 10 10 15 15 15 15 23 23 32 32 5 5 5 5 5 5 5 5 13 13 13 13 5 5 5 9 20 5 5 5 5 5 5 10 10 10 10 10 10 Page 2 of 2 Table 2 - Summary of Vapor Saturation Limits for Selected VOCs 1 VOC Maximum Concentration Measured in Soil Vapor Saturated Vapor Density Vapor Concentration Corresponding to 25% Activity Xylene 7.2 µg/L 4.3 x 106 µg/L 1.1 x 106 µg/L Toluene 3.0 µg/L 3.8 x 106 µg/L 1.0 x 10 µg/L 333,333 1,2,4- Trimethylbenzene 1.8 µg/L 4.9 x 106 µg/L 1.2 x 106 µg/L 666,667 Ethylbenzene 1.4 µg/L 4.3 x 106 µg/L 1.1 x 106 µg/L 785,714 1,3,5 Trimethylbenzene 0.9 µg/L 4.9 x 106 µg/L 1.2 x 10 µg/L Tetrachloroethylene 0.3 µg/L 6.8 x 106 µg/L Maximum Combined Total 15.2 µg/L 4.8 x 106 µg/L Factor of Safety = 25% Activity Vapor Concentration / Maximum Measured Vapor Concentration 6 1 Factor of Safety 152,778 6 1,333,333 1.7 x 10 µg/L 6 5,666,667 1.2 x 106 µg/L 78,941 Table 3 - Comparison of Maximum Measured Soil Gas VOC Levels wih OSHA Permissible Exposure Levels 1 VOC Maximim Measured Soil Gas Concentration (µg/L) 1,1‐Dichloroethane 0.11 400 1,2,4Trimethylbenzene 1.80 N.L. 1,3,5Trimethylbenzene 0.88 N.L. Benzene 0.33 3.4 Bromodichloromethane 0.29 N.L. Carbon disulfide 0.17 67.1 Chloroform 0.43 9.6 cis‐1,2Dichloroethene 0.02 N.L. Dibromochloromethane 0.19 N.L. Dichlorodifluoromethane 0.13 N.L. Ethylbenzene 1.40 21.8 Isopropylbenzene 0.14 N.L. Xylenes 7.20 435 Naphthalene 0.05 0.5 n‐Butylbenzene 0.04 N.L. n‐Propylbenzene 0.41 N.L. p‐Isopropyltoluene 0.08 N.L. sec‐Butylbenzene 0.03 N.L. Styrene 0.05 459 Tetrachloroethene 0.26 730 Toluene 3.00 811 Trichloroethene 0.05 579 Trichlorofluoromethane 0.02 N.L. OSHA Permissable 8-hour Exposure Limit. N.L. - Not Listed 1 OSHA PEL (µg/L) Main St Geotechnical Environmental Engineers 4 4.. CE V9). . . a a? 1% fly! 1: ?93 a ?13Page Roi . 905; Watt Pl - San Diego W. 1, 0 0.5 1.0Mile 5 Approximate Scale GeoKmetlcs Site Location Map Project Name: Otay Ranch Village 3 Development - Chula Vista, CA Date: December 2017 Figure 1 Limits at man Lanulill 0.. Legend Geotechnical El Residential Lots Environmental Engineers Recent Aerial Photograph Of Site Aerial Photograph by Google Earth Pro, November 8, 2016. $600 feet Project Name: Otay Ranch Village 3 Development - Chula Vista, CA Approximate Scale Date: December 2017 Figure 2 LOT 816 317 (9 SGP-327 Heritage Road Corte Nueva l\ l\ 767 740 735 734 729 GP-824 . 720 725 726 mino MeandroCamino Aldea Camino Carmelo 560 692 ?135 136 137 133 139 140 141 142143 144145 822 557 562 591 688 685 632 679 676 673 670 667 665 \130 129 123 127126 125 124 11>: 550 569 Camlno Avalon Corte Nueva Camino Prado LOT 524 541 525 54? Corte Mendi 526 539 464 475 527 533 466473 $335358 33 467 472 Calle Deceo 468 471 355 356 357 Mal/7 81 feet Legend 348 Residential Lot With Lot Number Soil Gas Probe Location and Designation (40 Installations Total) Depth of Sampling Probe Tip in Feet (75 Sampling Tips Total) 0 325 650 feet 5 Approximate Scale Geotechnical GeoKinetics Environmental Engineers Site Plan With TRC Gas Probe Locations Project Name: Otay Ranch Village 3 Development - Chula Vista, CA Date: December 2017 Figure 3 Probability of Exceedance 100 90-? 80-? 70-? 60- 50- 40- 30- 20-? Ml?l?age "all?l' Total ?00 concentration at 99 samoles (2.2 [Ill/l.) Ellamolo: Probability That The Total lloo Ilallnl' concentration Al Location Total Soil Vapor VOC Concentration (pg/L) 13 14 15 16 GeoKinetics Geotechnical Environmental Engineers Project Name: Otay Ranch Village 3 Development - Chula Vista, CA Date: December 2017 Probability of Exceedance Based On Measured Soil Gas VOC Levels Figure 4 .2 3? 7 0, SGP-817 .Heritage Road on an 3 ur'7ua Corte Nueva 766 '7 41 767 741 7 743 740 735 734 729 GP-824 711 717 722 33/426P11711716 /721Camlno Misandro ?g 761 753 71 /710708 702 45Camlno Aldea Camino Carmelo 142143 144145 557 562 591 688 685 662 679 676 673 670 667 665 ?126 127126 125 124 23 122 121 SGP-L AWestEast (5 LOT 552 567 197 150151 535 540 641 644 647 652 653 656 659 664 550 569 Camlno Avalon 59 4 . i 119 . 2191 570 ?73 2 SG-. 0 120 I 190 c88888888888m? 198 189 548 571?? cocococococococococoo$