APPENDIX I-3 Air and Fugitive Dust Monitoring and Mitigation

Transcription

1 APPENDIX I-3 Air and Fugitive Dust Monitoring and Mitigation (Tetra Tech 2014)

2 MEMO To: Cc: From: Jason Han, New Urban West, Inc. Keith Walker, Cox, Castle & Nicholson, LLP Carl Lenker, Senior Project Engineer; Ronald J. Marnicio, PhD, PE, Risk Assessment Discipline Lead Date: July 28, 2014 Subject: Air and Fugitive Dust Monitoring and Mitigation INTRODUCTION Soil at the above-referenced Oak Creek property (hereafter, the Site ) will be disturbed in connection with remedial excavation work and to grade the Site in preparation for redevelopment. At locations of the Site where imported fill is present, heavy metals (such as antimony, arsenic, thallium and selenium) have been detected at concentrations that exceed the U.S. Environmental Protection Agency (U.S. EPA) Residential Soil Regional Screening Levels (RSLs) and/or background concentrations for heavy metals in soil in California. More specifically, antimony was detected at concentrations up to 2.5 milligrams per kilogram (mg/kg) (compared to the RSL of 31 mg/kg and an average background concentration of 0.6 mg/kg); arsenic was detected at concentrations up to 33 mg/kg (compared to the RSL of 0.67 mg/kg and an average background concentration of 3.5 mg/kg); thallium was detected at concentrations up to 2.5 mg/kg (compared to the RSL of 0.78 mg/kg and average background of 15.7 mg/kg); and selenium was detected at concentrations up to 2.2 mg/kg compared to the RSL of 390 mg/kg and average background of 0.8 mg/kg. Therefore, in consideration of the presence of these hazardous substances in the disturbed soil, Tetra Tech has evaluated the potential exposure to dust by off-site receptors (e.g., adjacent residents) and how potential exposure to dust will be managed in regard to on-site receptors (construction workers) in relation to applicable regulatory requirements during the remedial excavation and Site grading processes. The remedial excavation will also address a small pocket of petroleum hydrocarbonimpacted soil. The petroleum hydrocarbon concentrations are de minimis in nature and can be managed pursuant to the processes discussed below. In addition, due to releases of hazardous substances from the nearby Chatham Brothers Barrel Yard Site, groundwater flowing beneath the Site may be impacted by low concentrations of volatile organic compounds (VOCs) that include without limitation trichloroethylene (TCE) and its breakdown products. Based on the grading plan for the Site, the grading contractor has concluded that neither groundwater nor soil in contact with the groundwater is likely to be disturbed during the development of the Site. In an abundance of caution, however, Tetra Tech s evaluation includes an analysis of potential risks posed by VOCs in groundwater. ON-SITE RECEPTORS (ON-SITE CONSTRUCTION WORKERS) Remedial excavation work and grading activities will be performed at the Site pursuant to a Site Health & Safety plan developed in accordance with 29 CFR (i.e., the Hazardous Waste Operations and Emergency Response, also known as the HAZWOPER standard). In compliance with this standard, all personnel dealing with disturbed soil at the Site will have the training, experience and medical clearance to work on the Site. In Tetra Tech, Inc Von Karman, Suite 500, Irvine, CA Tel Fax tetratech.com

3 Air and Fugitive Dust Monitoring and Mitigation July 28, 2014 addition, ongoing air monitoring will be performed within the areas in which on-site workers may inhale airborne dust or vapors during period of earth movement activities. The potential need for mitigation measures for worker protection will be evaluated based on comparison of air monitoring results to s that will be based on the Occupational Safety and Health Administration (OSHA) Permissible Limit (PEL) for arsenic of 0.01 milligrams per cubic meter (mg/m 3 ) and the PEL for TCE of 100 ppm. Arsenic will act as the surrogate for all other particulate exposures because it has the most stringent respirable dust action level of all the potential dust contaminants at this site and TCE will act as the surrogate for VOCs because it is the hazardous constituent potentially present in groundwater at the highest concentration. In the event the results of ongoing air monitoring indicate contaminant concentrations at least 75% of the established s, developed using the PELs for arsenic and TCE, exposure risks will be controlled through the use of personal protective equipment by workers at the Site to prevent their exposure to these contaminants. Such personal protective equipment will be specified in a site-specific health and safety plan. The use of this equipment is designed to minimize the risk of exposure of contaminants by the on-site workers. OFF-SITE RECEPTORS In addition to the air monitoring performed during earth movement activities within the areas in which on-site workers may inhale airborne dust, air monitoring will also be performed downwind of the earth movement activities at the boundaries of the Site. The monitoring results will be compared to exposure limits and sitespecific health-based air action levels will be developed in consideration of the characteristics of the soils that will be disturbed at the Site, as discussed in further detail below. With respect to hazardous substances dissolved in groundwater (e.g., TCE), Tetra Tech projects that the risk of exposure to off-site receptors will be well below health-based exposure limits because sampling results indicate TCE concentrations in groundwater are only present at approximately 5 to 10 parts per billion (ppb). At these low concentrations, the release of VOCs into the air from groundwater would be exceedingly limited. In addition, should any emissions actually reach ground surface, considerable mixing and dispersion in ambient air would reduce airborne contaminant concentrations to concentrations well below public health-based limits. In light of the foregoing considerations, the concentrations at or near off-site receptors would be far below all published California health-based exposure limits. Further, as stated above, no disturbance of groundwater or soil in contact with groundwater is anticipated in connection with development of the Site, and perimeter air monitoring will be ongoing during site grading activities to ensure both worker and public health protection. Development of the Health-Based Air s The applicable acute (short term) and chronic (long term) exposure limits for the contaminants of interest were tabulated and are set forth in Tables 1 and 2 to this memorandum. In connection with its evaluation, Tetra Tech considered (1) the acute and chronic Office of Environmental Health Hazard Assessment Reference Limits, (2) the San Francisco Bay Regional Water Quality Control Board Indoor Air Environmental Screening Levels, and (3) the U.S. EPA Indoor Air RSLs. The constituent-specific health-based exposure limits were reviewed to identify the most stringent acute and chronic exposure limit for each chemical constituent. The acute criteria represent air concentrations that a member of the public should not be exposed to for more than approximately one hour. The chronic criteria represent air concentrations that the public should not be exposed to for an extended period of months or years (typically, more than 7 years). Because the planned excavation and grading activities are expected to last no more than approximately 3 months (and any resulting exposures would, therefore, be considered subchronic in duration), the tabulated chronic criteria would be sufficiently conservative and protective of the much shorter duration planned activities. Based on the understanding that fugitive dust will contain essentially the same chemical composition as the soil being disturbed, the available historical soil data for the Site were tabulated and the maximum and average 2 TETRA TECH, INC.

4 Air and Fugitive Dust Monitoring and Mitigation July 28, 2014 constituent concentrations were calculated for (A) the areas to be excavated (see Table 1) and (B) the area to be subsequently graded (see Table 2). The soil samples associated with these data were collected from depths of 0.5 to 4.5 feet below ground surface, with most of the samples being from the top 6 to 18 inches. As such, the data is representative of the near-surface soil that will be excavated or graded. For comparison, Tables 1 and 2 also list the U.S. EPA Residential Soil RSL and the California background concentrations (both maximum and average). dust action levels were calculated for each constituent in consideration of the most stringent available acute or chronic public exposure limit. Because of the short-term nature of acute exposures, the acute action level was conservatively calculated using the acute exposure limit and the maximum measured soil concentration. The chronic action level was calculated using the chronic exposure limit and the average measured soil concentration of that constituent. The action level is the applicable exposure limit divided by the corresponding soil concentration, with a multiplicative factor of 1,000 to convert the units. Tables 1 and 2 show the results of these calculations for the area to be excavated and the area to be graded, respectively. Tables 1 and 2 also identify which of either the acute or chronic action level was the lowest. As seen, the most stringent health-based action level was nearly always based on the chronic or long-term exposure limit. Only the action level for copper was based on an acute exposure limit. These action levels would be interpreted as respirable dust (i.e., particulate matter less than 10 micrometers in diameter [PM 10 ]). U.S. EPA estimates in AP 42 that roughly 75% of fugitive dust from land clearing and bulldozing operations is PM 10. As such, the higher actions levels for total dust mass could be estimated by dividing the Table 1 or 2 action levels by Health-Based Air Excavation Activities Table 1 shows that only three of the listed metals are indicated to be present at levels above background concentrations in the excavation areas: antimony, arsenic and selenium. The average and maximum concentrations of the other metals are indicated to be consistent with background. Metals that have concentrations that are consistent with background concentrations were excluded from the health-based risk calculations as they are considered naturally-occurring. In consideration of these three naturally-occurring metals and the other anthropogenic constituents, limiting respirable dust concentrations to mg/m 3 or less at potential public exposure locations would ensure that all of the non-background constituent health-based exposure limits would be met. Health-Based Air Site Grading Activities Table 2 shows that only two of the listed metals are indicated to be present at levels above background in the area to be graded: antimony and selenium. The average and maximum concentrations of the other metals are indicated to be consistent with background. In consideration of these two naturally-occurring metals and the other anthropogenic constituents, limiting respirable dust concentrations to 117 mg/m 3 or less at potential public exposure locations would ensure that all of the non-background constituent health-based exposure limits would be met. This dust concentration is relatively high and would not be likely to be generated by typical re-grading and soil handling activity. Dust Mitigation Measures In order to prevent exposure to off-site receptors by dust that may become airborne during earth movement activities at the Site, dust migration will be minimized by the mitigation measures specified below. These measures will also serve to further protect on-site receptors (i.e., construction workers). If, during the excavation activities, the absolute PM 10 concentration on-site rises to a level that is 75% or more of the lowest identified fugitive dust health-based air action level derived (as specified above), the following dust mitigation measures will be employed: 3 TETRA TECH, INC.

5 Air and Fugitive Dust Monitoring and Mitigation July 28, 2014 (1) Water (or another non-hazardous agent) will be applied to exposed soil to prevent dust migration from arising during earth movement activities (e.g., excavation and/or grading); (2) Water will be applied to stockpiled soil, which will also be covered with plastic sheeting to prevent dust migration; and (3) During periods of high wind (i.e., instantaneous wind speeds exceeding 25 miles per hour as measured by an anemometer), earth movement activities will be discontinued until wind speeds decrease to speeds less than 25 miles per hour. CONCLUSION Based on the currently-available data, by employing the mitigation measures specified above and adhering with the other identified worker protection requirements for particulates and vapors, there should be no exposure by on-site receptors to dust or vapor containing hazardous substances at levels exceeding the appropriate occupational limits. In addition, as discussed above, there should be no exposure by off-site receptors to dust or vapors containing hazardous substances at levels exceeding appropriate public health-based limits. 4 TETRA TECH, INC.

6 Table 1. Air Monitoring Development for the Excavation Area New Urban West, Inc. - Oak Creek Escondido, CA OEHHA RELs [1] Dec-13 May-14 May-14 Mar-96 Mar-96 SFBRWQCB [2] USEPA [3] Site-Specific [4] Site-Specific [4] USEPA [3] UC [5] UC [5] Lowest Acute Lowest Excavation Area Maximum Excavation Area Average CA Background (Max) CA Background (Ave) Acute Soil Dust (Maximum) More Stringent Acute REL [6] REL Indoor Air ESLs Indoor Air RSLs Residential Soil RSLs (ug/m 3 ) (ug/m 3 ) (ug/m 3 ) (ug/m 3 ) (ug/m 3 ) (ug/m 3 ) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/m 3 ) (mg/m 3 ) (mg/m 3 ) METALS Antimony NL NL NV 0.21 NL Yes Arsenic Yes Barium NL NL NL No Beryllium NV NV No Cadmium NV NV No Chromium (Total) NL NL NV NV NL NV No Chromium (VI) NV NV Cobalt NL NL NL No Copper 100 NV NV NV 100 NV Acute No Lead NL NL NV 0.15 NL No Mercury No Molybdenum NL NL NV NV NL NV No Nickel No Selenium NV 20 NV 21 NV Yes Silver NL NL NV NV NL NV No Thallium NL NL NV NV NL NV No Vanadium 30 NV NV No Zinc NL NL NV NV NL NV No PESTICIDES alpha-bhc NL NL NL 6300 NL NL NL E E ,4'-DDD NL NL NL NL NL ,4'-DDE NL NL NL NL NL ,4'-DDT NL NL NL NL NL Chlordane (Tech) NL NL NL NL NL Basis Is Constituent Present in Concentrations Greater than CA Background? ORGANICS Benzene NL NL 3.88E p-isopropyltoluene NL NL NL 420 NL NL NL E E Naphthalene NV NV NL NL E E Toluene NL NL E E ,2,4-Trimethylbenzene NL NL NL 7.3 NL NL NL E E Diesel Range Organics (DRO) NL NL 140 NV NL NL NL NL NOTES NV No for listed constituent NL Constituent not listed REFERENCES [1] OEHHA Reference Levels; [2] San Francisco Bay regional Water Quality Control Board, 2013 Tier 1 Environmental Screening Levels, December 2013 [3] USEPA Regional Screening Level (RSL) Summary Table (TR=1E-6, HG=1), May 2014 [4] Historical Soil Analytical Data, New Urban West, Inc. - Oak Creek Property (Table 1) [5] Kearney Foundation Special Report, "Background Concentrations of Trace and Major Elements in California Soils" March 1996 [6] Arsenic also has an OEHHA 8-Hour REL

7 Table 2. Air Monitoring Development for the Re-Grading Area New Urban West, Inc. - Oak Creek Escondido, CA OEHHA RELs [1] Dec-13 May-14 May-14 Mar-96 Mar-96 SFBRWQCB [2] USEPA [3] Site-Specific [4] Site-Specific [4] USEPA [3] UC [5] UC [5] Lowest Re-Grading Area Maximum Re-Grading Area Average Acute Soil Dust (Maximum) More Stringent Lowest Acute CA Background CA Background Acute REL [6] REL Indoor Air ESLs Indoor Air RSLs Residential Soil RSLs (Max) (Ave) (ug/m 3 ) (ug/m 3 ) (ug/m 3 ) (ug/m 3 ) (ug/m 3 ) (ug/m 3 ) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/m 3 ) (mg/m 3 ) (mg/m 3 ) METALS Antimony NL NL NV 0.21 NL Yes Arsenic No Barium NL NL NL No Beryllium NV NV No Cadmium NV NV No Chromium (Total) NL NL NV NV NL NV No Chromium (VI) NV NV Cobalt NL NL NL No Copper 100 NV NV NV 100 NV Acute No Lead NL NL NV 0.15 NL No Mercury No Molybdenum NL NL NV NV NL NV No Nickel No Selenium NV 20 NV 21 NV Yes Silver NL NL NV NV NL NV No Thallium NL NL NV NV NL NV No Vanadium 30 NV NV No Zinc NL NL NV NV NL NV No PESTICIDES alpha-bhc NL NL NL 6300 NL NL NL E E ,4'-DDD NL NL NL NL NL ,4'-DDE NL NL NL NL NL ,4'-DDT NL NL NL NL NL Chlordane (Tech) NL NL NL NL NL Basis Is Constituent Present in Concentrations Greater than CA Background? ORGANICS Benzene NL NL 4.64E p-isopropyltoluene NL NL NL 420 NL NL NL E E Naphthalene NV NV NL NL E E Toluene NL NL E E ,2,4-Trimethylbenzene NL NL NL 7.3 NL NL NL E E Diesel Range Organics (DRO) NL NL 140 NV NL NL NL NL NOTES NV No for listed constituent NL Constituent not listed REFERENCES [1] OEHHA Reference Levels; [2] San Francisco Bay Regional Water Quality Control Board, 2013 Tier 1 Environmental Screening Levels, December 2013 [3] USEPA Regional Screening Level (RSL) Summary Table (TR=1E-6, HG=1), May 2014 [4] Historical Soil Analytical Data, New Urban West, Inc. - Oak Creek Property (Table 1) [5] Kearney Foundation Special Report, "Background Concentrations of Trace and Major Elements in California Soils" March 1996 [6] Arsenic also has an OEHHA 8-Hour REL