Appendix D. Soil Cover

Transcription

1 Appendix D Soil Cover

2 Table of Contents Page D.1 Background... D-1 D.2 Soil Cover Operations and Maintenance (O&M)... D-2 D.3 Remedial Investigation Soil Cover Sampling Summary... D-2 D.4 Recent Soil Cover Sampling... D-3 D.4.1 Soil Cover Sampling Procedures... D-3 D Soil Cover Sampling... D-4 D Soil Cover Sampling... D-9 D.4.4 Discussion of Recent Soil Cover Sampling Results... D-9 D.5 Updated Risk Assessment... D-13 D.6 Protectiveness Statement... D-13 D.7 References... D-13 List of Tables Page Table D-1: List of Parameters and Methods 2004 Sampling... D-5 Table D-2: Recent Soil Cover Sampling Results October D-6 Table D-3: Recent Soil Cover Sampling Results D-10 Table D-4: Summary of RI and Recent Soil Cover Sampling... D-11 List of Figures Figure D-1: Figure D-2: Figure D-3: Remedial Investigation Soil Sampling Locations 2004 Soil Cover Sampling Locations 2008 Soil Cover Sampling Locations List of Sub-Appendices D-A Technical Memorandum Cover Soil Sampling, Sanitation Districts, August 2008 D-i

3 Appendix D: Soil Cover D.1 Background The (Site) was closed in 1980 after reaching its capacity. All areas of the landfill are covered with a cap of approximately 7 feet of low permeability soil, which is regularly inspected and maintained. Low spots in the cap caused by normal landfill settlement are filled with soil to ensure that water does not pond on the landfill. The surface cap and the landfill gas collection system prevent exposure to chemicals of potential concern contained within the landfill. The final soil cover at the landfill includes both native and imported offsite sources; hence, the surface materials represent a variety of different soil types and qualities. A Remedial Investigation (RI) was conducted to characterize the nature and extent of contamination at and from the Site. All potential media and pathways for contaminant transport from the Site were assessed. The RI evaluated potential health risks associated with chemicals in Site surface soils, regardless of the source (i.e., native or imported). This Appendix discusses surface soil testing conducted during the historic RI period and recent testing conducted as part of the. A comprehensive program of field investigations was undertaken to characterize Site conditions during the RI. The surface soil investigation included soil cover sampling at 56 locations with analysis for organic and metal constituents. A risk assessment of impacts to human health and the environment from the landfill was also conducted as part of the RI. The Risk Assessment found no potential health risks associated with surface soils with the exception of one area near a maintenance road where polyaromatic hydrocarbons (PAHs) were detected. The source of PAHs was believed to be from asphalt roads at the landfill. This localized area was retested during this Five-Year Review to assess RI PAH results. Additional cover soil has been brought to the Site since the RI was conducted to fill low areas that occur due to normal settling of refuse in the landfill and for South Coast Air Quality Management District (SCAQMD) AQMD compliance activities. The Citizens Advisory Board (CAB) raised concerns about potential contaminants in soils imported after the RI. In order to address concerns regarding environmental risks associated with recently imported soil cover, a supplemental program of soil cover testing was conducted during. Because the surface soils represent both onsite and imported offsite soils from different sources, they exhibit a wide range of concentrations of naturally occurring compounds. Data obtained during the RI and were conservatively used to assess potential environmental and health risks associated with Site surface soils during an updated health risk assessment presented in Appendix J. Results of the surface soil sampling conducted during the RI and as part of this Five-Year Review are discussed in this Appendix. D-1

4 D.2 Soil Cover Operations and Maintenance (O&M) Site personnel perform visual observations of the landfill cover and note the presence of fissures or differential settlement. Sanitation Districts personnel or contractors make routine repairs as necessary. Maintenance work is documented in a work log maintained by the Sanitation Districts. As necessary, the Sanitation Districts import soils to these areas so that the surface topography of the minimizes ponding and infiltration of water. In addition, imported soil is periodically used to repair fissures in the soil cover for South Coast Air Quality Management District (SCAQMD) compliance activities. D.3 Remedial Investigation Soil Cover Sampling Summary Soil cover at the Site is a heterogeneous mixture of native alluvium and bedrock and imported soils from offsite sources. While the cover soils are diverse in nature, they are primarily alluvium and bedrock of marine origin, which was the dominant depositional mechanism in the Palos Verdes area during recent geologic periods. A total of 56 soil cover samples were collected during the RI. Samples were collected from various areas of the Site including heavily used areas such as the equestrian center, the horse trail, and the South Coast Botanic Garden s lake and stream area. Samples representing background conditions were also collected from offsite borings around the landfill. The onsite surface soil sample locations are shown as green triangles in Figure D-1. Soil cover samples were analyzed variously for general parameters, metals, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and PAHs during the RI evaluation (Sanitation Districts, June 1995a). Two soil cover sampling programs were implemented during the RI in October 1990 and October Soil cover materials tested represented both native and imported soil. The October 1990 program collected samples from 34 locations and analyzed the samples for general parameters, metals, VOCs, and SVOCs. The October 1993 program collected 22 samples and analyzed the samples for same suite of parameters plus PAHs. PAHs are a subset of SVOCs and were analyzed by an additional method to determine their concentrations at lower detection limits. Background soil samples were collected from soil borings sampled during the RI. These background borings were either upgradient of the Site or in areas un-impacted by Site contaminants (Figure D-1). Because metals and general mineral and physical parameters occur naturally in alluvium and bedrock, background samples are used to provide a range of concentrations that are representative of natural geologic strata in the area. The background samples give a general indication of the ranges of metals and general minerals that might be found in cover materials at the Site. Since the soil cover is composed of a combination of native and imported soils from offsite sources, imported soils may exhibit naturally-occurring concentrations outside the range exhibited in background samples depending on the source rock. Data from common soils in the U.S. are also used to provide for comparison to a broader range of soil types (Dragun and Chiasson, 1991). D-2

5 Soil sampling activities were documented, and sampling results were compiled and analyzed in the RI (Sanitation Districts, June 1995a). Sampling results indicated that with respect to general minerals and metal constituents, the soil cover was similar to background soils. One or more soil cover samples were found to contain three VOCs at low concentrations (maximum detections: toluene = 0.02 milligram per kilogram (mg/kg), o-xylene = 0.01 mg/kg, and m+p xylene = 0.02 mg/kg). A few SVOCs were detected at low concentrations; however, these detections were sporadic with no associated trends. Some elevated PAHs were detected near the third bench access road. It was determined that these detections were likely related to pieces of asphalt entrained in the soil samples. D.4 Recent Soil Cover Sampling Two soil cover sampling investigations were conducted during the. The first investigation, conducted in 2004, had two goals 1) verification of PAH detections in one area of the landfill identified during the RI, and 2) assessment of recently imported soil to address concerns raised by the CAB. The second investigation was conducted in 2008 at the request of Department of Toxic Substances Control (DTSC) to confirm previous arsenic detections obtained during the RI, assess the lateral extent of any confirmed detections, and re-evaluate background levels within the cover soil at the Site. In response to DTSC s request, the Sanitation Districts remitted Technical Memorandum Cover Soil Sampling at, dated August 2008, included as Sub-Appendix D-A. Data obtained from these studies were used in the updated health risk assessment conducted as part of the and described in Appendix J. D.4.1 Soil Cover Sampling Procedures A work plan for supplemental soil cover sampling was included in the Work Plan (Todd and RBD, May 2004) and revised in August 2004 based on comments received from DTSC. Soil cover samples collected in 2004 and 2008 were collected in accordance with sampling procedures and protocols presented in the work plans and approved by DTSC. During the 2004 investigation, soil samples were collected on October 26, During the 2008 investigation, samples were collected on February 21, March 20, and April 8, A field log notebook was kept during soil sampling documenting field sampling activities, measurements, and environmental conditions. Evidence of odors and visual indications of contamination at the sampling locations were documented in the field log book. No visual indications of contamination were observed and no odors were detected during the recent soil cover sampling investigations. Sampling activities conducted by Todd Engineers and Sanitation Districts were overseen by DTSC staff. Relatively undisturbed shallow soil samples were collected using a hammer driven core sampler. The core sampler was lined with stainless steel liners. Prior to taking the samples, surficial materials including grass and plant material, wood chips, and other extraneous material were removed from the sampling site. The core sampler and sample liner were hammered into the ground to a depth approximately 6 to 24 inches below D-3

6 ground surface (bgs). Once the intended depth was reached, the core sampler was twisted to shear the sampler off the bottom of the core hole. The core sampler was removed from the ground and the sample liner removed from the sampler. The ends of the sample liner were sealed with Teflon tape and capped with plastic caps. The tubes were labeled with the site name, sample number, sample depth, sampler, and sample date. Soil samples were stored in an ice chest and maintained at 4 degrees Centigrade prior to and during transport to the Weck Laboratories, Inc. in City of Industry, California for analyses. Weck Laboratories is a California certified laboratory. All equipment was washed and rinsed to decontaminate between sampling locations. During the 2004 sampling, one duplicate sample was collected at sample locations SC- 73/74 in the area of PAH detections. For the 2008 sampling, one duplicate sample was collected at SC-93/SC-93D. For the duplicates, a second core sample was collected adjacent to the first locations. Soil was removed from the two liners, placed together in a stainless steel container, and mixed with a stainless steel spoon to homogenize or composite the samples. Then the mixed samples were placed back into the liners and sealed. To establish the documentation necessary to trace sample possession, a chain of custody form was used. Every sample collected for analysis was logged on this form along with the requested analyses, time and data of sample collection, and sample media. The chain of custody form accompanied the sample until it was discarded. D Soil Cover Sampling Additional imported cover soil has been brought to the Site since the RI was conducted to fill low areas that occur due to normal settling of refuse in the landfill and for SCAQMD Rule compliance activities. The purpose of the 2004 soil cover testing was to determine if there are contaminants in recently imported soil cover material that may pose risk to human health or the environment and to verify detections of PAHs in one area of the Site identified during the RI sampling. Figure D-2 shows the areas of the Site where imported soils have been placed in recent years. As shown in the figure, during the RI soil cover sampling, PAHs were detected on one of the benches in the northern corner of the Main Site. Cover soil samples were collected in October 2004 in areas of recent filling and the area of PAH detections. The sample locations are shown on Figure D-2. Eighteen samples locations were tested. One duplicate sample was collected at the area of PAH detections for a total of 19 samples. The samples were numbered SC-57 through SC-75 continuing the naming convention used during the RI. A handheld Ground Positioning System (GPS) instrument was used to record the soil sample locations and elevations. Soil samples collected in 2004 were analyzed for general mineral and physical parameters, metals, SVOCs, and PAHs. Table D-1 lists the parameters and USEPA methods and detection limits. The Weck Laboratory report is included in Sub-Appendix D-A. Soil cover sampling results are presented in Table D-2. No SVOCs or PAHs were detected in any of the 2004 soil cover sampling. Duplicate samples SC-73 and SC-74 D-4

7 showed reasonably consistent results relative to each other. The duplicates should have similar results and were run to check the accuracy of the laboratory analyses. Table D-1: List of Parameters and Methods 2004 Sampling General Constituent EPA Method Detection Limits (mg/kg) ph 9045C Conductivity SM2510B-M Nitrate (as Nitrogen) Sulfate Chloride Oil & Grease 1664M 25 Hydrocarbons Modified 8015B Gas range (0.5), diesel range (10.0) Metals Calcium 6010B 25 Magnesium 6010B 25 Arsenic 6010B 1.0 Barium 6010B 0.1 Cadmium 6010B 1.0 Total Chromium 6010B 0.1 Hexavalent Chromium Cobalt 6010B 1.0 Iron 6010B 25 Lead 6010B 1.0 Manganese 6010B 5.0 Mercury 7471A 0.1 Nickel 6010B 1.0 Potassium 6010B 50 Selenium 6010B 0.5 Silver 6010B 0.5 Sodium 6010B 50 Zinc 6010B 1.0 Antimony 6010B 5.0 Beryllium 6010B 0.5 Molybdenum 6010B 2.0 Thallium 6010B 0.5 Vanadium 6010B 1.0 Semi-Volatile Organic Compounds 8270C Polycyclic Aromatic Hydrocarbons 8270C < 0.05 (using B[a]P) as surrogate B[a]P Benzo(a)pyrene mg/kg milligrams per kilogram D-5

8 Table D-2: Recent Soil Cover Sampling Results October 2004 Constituent Units SC-57 SC-58 SC-59 SC-60 SC-61 SC-62 SC-63 SC-64 SC-65 SC-66 SC-67 SC-68 SC-69 SC-70 SC-71 SC-72 SC-73 SC-74 SC-75 General Chloride, Water Leachable mg/kg Nitrate as N, Water Leachable mg/kg < < Oil & Grease mg/kg 750 2,000 1, ,400 1, , < 500 1,000 ph ph Units Specific Conductance (EC) umhos/cm ,900 2, ,000 4,700 1,100 Sulfate, Water Leachable mg/kg , ,000 10, Metals Calcium mg/kg 36,000 5,600 13,000 3,500 21,000 4,800 4,600 15,000 2,200 10,000 15,000 13,000 27,000 25,000 27,000 9,200 5,100 5,100 2,600 Chromium, Hexavalent mg/kg < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < Magnesium mg/kg 12,000 4,700 6,600 3,600 4,800 3,300 4,100 5,400 5,600 7,500 6,800 5,800 7,600 6,700 11,000 4,200 5,700 5,300 3,100 Mercury, Total ug/kg Potassium mg/kg 1,700 1,700 1,300 3,100 2,100 2,200 2,300 3,800 3,700 3,900 4,700 4,100 3,600 2,500 2,500 1,400 4,300 3,900 3,000 Sodium mg/kg Total Antimony mg/kg < < Total Arsenic mg/kg Total Barium mg/kg 1, Total Beryllium mg/kg < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < < 0.5 < 0.5 < < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 Total Cadmium mg/kg Total Chromium mg/kg Total Cobalt mg/kg Total Iron mg/kg 13,000 19,000 12,000 15,000 14,000 14,000 16,000 19,000 25,000 18,000 27,000 27,000 20,000 17,000 14,000 13,000 20,000 17,000 12,000 Total Lead mg/kg < < 1 < < 1 < 1 < < 1 < 1 < < 1 < Total Manganese mg/kg Total Molybdenum mg/kg < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < < 5 < 5 < 5 < 5 < Total Nickel mg/kg Total Selenium mg/kg < 1 < 1 < < 1 < 1 < 1 < 1 < < 1 < 1 < < Total Silver mg/kg Total Thallium mg/kg < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 < 3 Total Vanadium mg/kg Total Zinc mg/kg Nonhalogenated Organic Compounds Diesel Range Organics mg/kg < 5 < 5 < 5 < 5 < 5 < 5 < 5 < < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 Gasoline Range Organics mg/kg < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 D-6

9 Table D-2: Recent Soil Cover Sampling Results October 2004 (continued) Constituent Units SC-57 SC-58 SC-59 SC-60 SC-61 SC-62 SC-63 SC-64 SC-65 SC-66 SC-67 SC-68 SC-69 SC-70 SC-71 SC-72 SC-73 SC-74 SC-75 Polycyclic Aromatic Hydrocarbons Acenaphthene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Acenaphthylene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Anthracene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Benzo (a) anthracene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Benzo (a) pyrene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Benzo (b) fluoranthene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Benzo (g,h,i) perylene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Benzo (k) fluoranthene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Chrysene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Dibenz (a,h) anthracene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Fluoranthene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Fluorene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Indeno (1,2,3-cd) pyrene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Naphthalene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Phenanthrene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Pyrene mg/kg < < 0.19 < < < 0.19 < < 0.19 < < < < 0.19 < < < < < < 0.19 < < Semi-Volatile Organic Compounds 1,2,4-Trichlorobenzene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 1,2-Dichlorobenzene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 1,2-Diphenylhydrazine mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 1,3-Dichlorobenzene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 1,4-Dichlorobenzene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 2,4,5-Trichlorophenol mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 2,4,6-Trichlorophenol mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 2,4-Dichlorophenol mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 2,4-Dimethylphenol mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 2,4-Dinitrophenol mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 2,4-Dinitrotoluene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 2,6-Dinitrotoluene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < Chloronaphthalene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < Chlorophenol mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < Methylnaphthalene mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 2-Methylphenol mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < Nitroaniline mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < Nitrophenol mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 3 & 4-Methylphenol mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 3,3 -Dichlorobenzidine mg/kg < 5 < 25 < 5 < 5 < 25 < 5 < 25 < 5 < 5 < 5 < 25 < 5 < 5 < 5 < 5 < 5 < 25 < 5 < 5 3-Nitroaniline mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 4,6-Dinitro-2-methylphenol mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 D-7

10 Table D-2: Recent Soil Cover Sampling Results October 2004 (continued) Constituent Units SC-57 SC-58 SC-59 SC-60 SC-61 SC-62 SC-63 SC-64 SC-65 SC-66 SC-67 SC-68 SC-69 SC-70 SC-71 SC-72 SC-73 SC-74 SC-75 Semi-Volatile Organic Compounds 4-Bromophenyl phenyl ether mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < Chloro-3-methylphenol mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 4-Chloroaniline mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < Chlorophenyl phenyl ether mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < Nitroaniline mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < Nitrophenol mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Aniline mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 Azobenzene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Benzidine mg/kg < 5 < 25 < 5 < 5 < 25 < 5 < 25 < 5 < 5 < 5 < 25 < 5 < 5 < 5 < 5 < 5 < 25 < 5 < 5 Benzoic acid mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Benzyl alcohol mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 Bis(2-chloroethoxy)methane mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Bis(2-chloroethyl)ether mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Bis(2-chloroisopropyl)ether mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 Bis(2-ethylhexyl)phthalate mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 Butyl benzyl phthalate mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Carbazole mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Dibenzofuran mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Diethyl phthalate mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Dimethyl phthalate mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Di-n-butyl phthalate mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Di-n-octyl phthalate mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Hexachlorobenzene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Hexachlorobutadiene mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 Hexachlorocyclopentadiene mg/kg < 1 < 5 < 1 < 1 < 5 < 1 < 5 < 1 < 1 < 1 < 5 < 1 < 1 < 1 < 1 < 1 < 5 < 1 < 1 Hexachloroethane mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Isophorone mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Nitrobenzene mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 N-Nitrosodimethylamine mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 N-Nitrosodi-n-propylamine mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 N-Nitrosodiphenylamine mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Pentachlorophenol mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Phenol mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 Pyridine mg/kg < 0.5 < 2.5 < 0.5 < 0.5 < 2.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 2.5 < 0.5 < 0.5 mg/kg - milligrams per kilogram; umhos/cm - micromhos per centimeter "<" - less than detection limit D-8

11 D Soil Cover Sampling The landfill cap is a heterogeneous mixture of native alluvium and bedrock and imported soils from offsite sources. As a result, the soil can exhibit a wide range of concentrations of naturally-occurring constituents. As described in the Sanitation Districts August, 2008, Technical Memorandum to DTSC, additional soil samples were obtained to verify arsenic results previously obtained during the RI. These data were collected to support the updated health risk assessment calculations as described in Appendix J. Figure D-3 shows the locations of soil cover samples originally collected during the RI and verification locations tested in The samples are located on the southeast side of the Main Site and the South Coast Botanic Garden. Soil cover samples were collected in February, March, and April 2008 around RI soil cover sample locations SC-10, SC-26, SC-27, SC-38, SC-43 and SC-45. A total of twenty-eight soil cover samples were collected including one duplicate sample (SC-93D) at SC-93. The samples were numbered SC-76 through SC-102 continuing the naming convention used during the RI and the 2004 sampling event. A handheld GPS instrument was used to record the soil sample locations and elevations. Soil samples collected in 2008 were analyzed for arsenic using USEPA Method 6010B. Laboratory reports are included in Sub-Appendix D-A. Soil cover sampling results are presented in Table D-3. In general, average 2008 results surrounding SC-10, SC-38, SC-43, SC-26, SC-27 and SC-45 were significantly lower than these initial single samples obtained during the RI. In addition, both the RI and 2008 results indicate that higher arsenic concentrations are not laterally extensive and results are consistent with heterogeneous natural soils. Duplicate samples SC-93 and SC-93D showed reasonably consistent results relative to each other. D.4.4 Discussion of Recent Soil Cover Sampling Results Table D-4 summarizes the soil sampling results for parameters with detections during the 2004, 2008, and RI soil cover sampling, RI background soil sampling, and metals in common soils in the U.S. (Dragun and Chiasson, 1991). Because metals and general mineral and physical parameters occur naturally in alluvium and bedrock, background samples are used to provide a range of concentrations that are representative of natural geologic strata in the area. Results are also compared to ranges found in common soils in the U.S. (Dragun and Chiasson, 1991). For the recent soil cover sampling and the RI background results, the number of samples, number of non-detects, range of results, and average concentrations are provided. Ranges are provided for the common U.S. soils and ranges for the RI soil cover samples. No SVOCs or PAHs were detected in the 2004 soil cover samples. Metals and general mineral sample results were generally within the range of local background soil samples and within the range of values found in common soils in the U.S. No evidence of PAHs was found and overall the data indicate that the imported soil is clean fill material and no contaminated soil has been used to fill low spots on the Site. D-9

12 Table D-3: Recent Soil Cover Sampling Results 2008 Around RI Sample SC-10 Around RI Sample SC-38 Around RI Sample SC-43 Around RI Sample SC-26 Around RI Sample SC-27 (As = 20 mg/kg) a (As = 14.2 & 15.8 mg/kg) a (As = 27.9 mg/kg) a (As = 15 mg/kg) a (As = 15 mg/kg) a Constituent Units SC-76 SC-77 SC-78 SC-79 SC-80 SC-81 SC-85 SC-86 SC-87 SC-88 SC-89 SC-90 SC-91 SC-92 SC-93 (Dup) SC-93 Total Arsenic mg/kg Average Arsenic b mg/kg Around RI Sample SC-45 (As = 14.1 mg/kg) a Constituent Units SC-82 SC-83 SC-84 SC-94 SC-95 SC-96 SC-97 SC-98 SC-99 SC-100 SC-101 SC-102 Total Arsenic mg/kg <2.7 Average Arsenic b mg/kg 12.5 (a) - RI - Remedial Investigation (Sanitation Districts, June 1995a) (b) Used 1/2 detection limits to calculate average unless all results were detected or all were non-detected mg/kg - milligrams per kilograms "<" - less than detection limit As arsenic Dup - Duplicate D-10

13 Table D-4: Summary of RI and Recent Soil Cover Sampling Constituent Units Recent Soil Cover Sample Results (2004 and 2008) Background Subsurface Soil Sample Results Common Range in Soils (a) Range in RI Soil Cover Samples (b) No. Analyzed Min Max Avg (c) No.ND No. Analyzed Min Max Avg (c) No.ND Min Max Min Max General Chloride, Water Leachable mg/kg , ,240 Nitrate as N, Water Leachable mg/kg 19 < < ND 343 Oil & Grease mg/kg 19 < 500 2, < 150 3, ND 17,000 ph ph Units Specific Conductance (EC) umhos/cm ,900 1, < ,850 1, ,100 Sulfate, Water Leachable mg/kg ,000 2, , ,100 Metals Calcium mg/kg 19 2,200 36,000 12, ,000 35, ,000 5,195 75,700 Magnesium mg/kg 19 3,100 12,000 5, ,000 16, > 100,000 2,140 19,600 Mercury, Total ug/kg < ND 1.17 Potassium mg/kg 19 1,300 4,700 2, ,240 2, ,900 63,000 1,510 7,223 Sodium mg/kg , < , ,481 Total Antimony mg/kg 19 < < < 1 2 ND 8.2 Total Arsenic mg/kg d d 4.00 d Total Barium mg/kg , , , ,220 Total Beryllium mg/kg 19 < < ND 3 ND 1.2 Total Cadmium mg/kg < ND 10.9 Total Chromium mg/kg , Total Cobalt mg/kg < ND 50 ND 16.4 Total Iron mg/kg 19 12,000 27,000 17, ,900 11, ,000 > ,340 32,400 Total Lead mg/kg 19 < < ND 300 ND 179 Total Manganese mg/kg , Total Molybdenum mg/kg 19 < < ND 5 ND 20 Total Nickel mg/kg < Total Selenium mg/kg 19 < < < ND 9.6 Total Silver mg/kg < < ND 4.55 Total Thallium mg/kg 19 < 3 < 3 ND < 0.5 < 0.5 ND 53 < ND 2.0 Total Vanadium mg/kg Total Zinc mg/kg D-11

14 Table D-4: Summary of RI and Recent Soil Cover Sampling (continued) Constituent Units Recent Soil Cover Sample Results (2004 and 2008) Background Subsurface Soil Sample Results Common Range in Soils (a) Range in RI Soil Cover Samples (b) No. Analyzed Min Max Avg (c) No.ND No. Analyzed Min Max Avg (c) No.ND Min Max Min Max Volatile Organic Compounds Toluene mg/kg NA ND 0.02 O-Xylene mg/kg NA ND 0.01 M+P-Xylene mg/kg NA ND 0.02 Semi-Volatile Organic Compounds Phenol mg/kg 19 < 0.5 < 2.5 ND 19 ND 8 Diethylhexyl Phthalate mg/kg NS ND 3 Polycyclic Aromatic Hydrocarbons Acenaphthene mg/kg 19 < < 2.5 ND 19 ND 15 Acenaphthylene mg/kg 19 < < 2.5 ND 19 Anthracene mg/kg 19 < < 2.5 ND 19 ND 11 Benzo (a) anthracene mg/kg 19 < < 5 ND 19 ND 16 Benzo (a) pyrene mg/kg 19 < < 2.5 ND 19 ND 15 Benzo (b) fluoranthene mg/kg 19 < < 2.5 ND 19 ND 15 Benzo (g,h,i) perylene mg/kg 19 < < 2.5 ND 19 ND Benzo (k) fluoranthene mg/kg 19 < < 2.5 ND 19 ND 15 Chrysene mg/kg 19 < < 2.5 ND 19 ND 18 Dibenz (a,h) anthracene mg/kg 19 < < 2.5 ND 19 ND Fluoranthene mg/kg 19 < < 2.5 ND 19 ND 42 Fluorene mg/kg 19 < < 2.5 ND 19 ND 11 Indeno (1,2,3-cd) pyrene mg/kg 19 < < 2.5 ND 19 ND 5 Naphthalene mg/kg 19 < < 2.5 ND 19 ND 21.5 Phenanthrene mg/kg 19 < < 2.5 ND 19 ND 48 Pyrene mg/kg 19 < < 2.5 ND 19 ND 45 (a) - Source for Ranges in Common Soils is Dragun and Chiasson (1991) mg/kg - milligrams per kilogram; NA - constituent not analyzed: (b) - RI - Remedial Investigation (Sanitation Districts, June, 1995a) Min - minimum; Max - maximum; Avg - average; ND - not detected; "<" - less than detection limit: ">" - greater than (c) Used 1/2 detection limits to calculate average unless all results were non-detected Average concentrations were calculated using 1/2 the given detection limit for ND samples (d) As described in Appendix D-A, background arsenic levels were re-evaluated by Nexus Environmental Services D-12

15 For the 2008 cover soil sampling, Table D-3 lists the RI arsenic levels detected and the nearby 2008 sampling results. Average 2008 results were considerably lower than RI results for RI samples SC-10, SC-38, SC-43, SC-26, SC-27 and SC-45. These 2008 results confirm cover soils at the Site are composed of a heterogeneous mixture of naturally occurring alluvium and bedrock. Data obtained during the RI, 2004, and 2008 cover soil sampling programs were used to conservatively estimate potential health risks associated with surface soils as discussed in Appendix J D.5 Updated Risk Assessment An updated health risk assessment was conducted as part of this and is included in Appendix J. With respect to the Site cover soils, the risk assessment considered incidental ingestion of soil, dermal contact with soil, and inhalation of soil particles released to the air as potential exposure pathways. The estimated potential adverse health impacts associated with exposure to cover soil through these three pathways are within the acceptable risk management goals established for the corresponding onsite land use conditions. D.6 Protectiveness Statement The soil cover is comprised of clean native and imported fill and the estimated potential health risks associated with exposure to cover soil are within the risk management goals established by DTSC for the corresponding onsite land use conditions. D.7 References County Sanitation Districts of Los Angeles County (Sanitation Districts), Remedial Investigation Report,, June 1995a. Dragun, James and Andrew Chiasson, Elements in North American Soils, Hazardous Materials Control Resources Institute, Greenbelt, Maryland, Todd Engineers (Todd) and Risk-Based Decisions, Inc. (RBD), Work Plan, May D-13

16 Figures

17 Ernie Howlett Park Main Site Upper Deck South Coast Botanic Garden N Scale in Feet August 2008 Figure D-1 TODD ENGINEERS Alameda, California Remedial Investigation Soil Sampling Locations

18 LEGEND Property Boundary Areas of Greater Than Normal Settlement Area of PAH Detections During Remedial Investigation Sampling SC-66 Soil Cover Sampling Location SC-75 SC-73/74 SC-70 Ernie Howlett Park SC-71 SC-72 SC-68 SC-69 SC-67 Main Site SC-58 SC-57 SC-63 SC-59 SC-64 SC-65 SC-66 South Coast Botanic Garden SC-60 SC-62 SC-61 N 0 Scale in Feet 750 August 2008 Figure D-2 TODD ENGINEERS Alameda, California 2004 Soil Cover Sampling Locations

19 N SC-80 (14.0) LEGEND 2008 Soil Cover Sampling Location Arsenic Concentration in mg/kg 0 Scale in Feet 300 SC-10 (20.0) RI Soil Cover Sampling Location Arsenic Concentration in mg/kg Property Boundary Main Site South Coast Botanic Garden August 2008 Figure D-3 TODD ENGINEERS Alameda, California 2008 Soil Cover Sampling Locations