TABLE 1 SSFL CHEMICAL SOIL BACKGROUND STUDY DATA QUALITY OBJECTIVES

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1 Problem Statement: Soil chemical concentration data for selected constituents are needed from off-site chemical background reference areas (CBRAs) to establish a regulatory-compliant, publicly-reviewed, and technically-defensible chemical soil background dataset to be used in Santa Susana Field Laboratory (SSFL) environmental programs for characterization and cleanup activities. Planning Team: The planning team is led by the Department of Toxic Substances Control (DTSC) and includes geologists, risk assessors, fieldwork specialists, and chemists. DTSC also incorporates Stakeholder input, including community members and other public and SSFL representatives into the planning. 1. State the Problem Conceptual Model: The release of chemicals from SSFL operations into soil has resulted in contamination above background concentrations. In order to determine the extent of contamination for characterization and risk assessment, as well as to set cleanup levels, background soil concentrations are needed. Resources, Constraints and Deadlines: Available resources include DTSC personnel and contractors, community members, other public stakeholders, and SSFL representatives and contractors who all provide input to the planning process. Financial resources are provided by the SSFL representatives. Constraints include two major issues: (1) representativeness of the background dataset to on-site conditions and (2) sufficient distance from the site to address public concern regarding the potential for offsite impacts due to airborne transport and deposition. Deadlines reflect the need to conduct work as soon as possible, since background data are needed for continuing project work and since data collection should be conducted before any significant fires affect the CBRAs. Principle Study Question: What are soil background concentrations for selected chemicals that are representative of SSFL soil characteristics for use in characterization and cleanup activities? 2. Identify the Goals of the Study Estimation Statement(s): The following goals are provided to guide development of the chemical background study: Locate and select off-site CBRAs with physical characteristics (geology, topography, soil type, etc.) similar to SSFL and that meet other study criteria (e.g., distant sites to address public concerns about off-site airborne contamination). Design an appropriate sampling and analysis plan that optimizes data representativeness, ensures data quality, and provides a dataset of sufficient size and strength to define background data distributions, conduct needed evaluations, and develop a background comparison statistic that provides a high level of confidence for decision making. Develop a Data Evaluation Plan (DEP) that defines usability, acceptance, and application criteria for background data; to evaluate data to establish a final representative SSFL background dataset; and defines procedures for final dataset use in characterization and cleanup activities (Note: DEP development is a separate task and not included in the Sampling and Analysis Plan). Page 1 of 6

2 3. Identify Information Inputs Information Needed to Resolve Decision Statements: Use of the chemical soil background data. Background soil data will be used for SSFL characterization sampling and cleanup decisions considering future land use and/or receptor scenarios in consideration of California State Senate Bill 990. Soil characteristic groups represented at SSFL. Based on geology and geomorphic landforms present at SSFL, four soil characteristic groups ( strata 1 ) are identified: Formation s Formation Non-s Santa Susana Formation s Santa Susana Formation Non-s Shallow and deep chemical concentrations. Background soil chemistry in nondrainage areas (hillsides and flat) may vary between shallow or deeper soils due to either geologic substrate materials or anthropogenic air dispersion and deposition (i.e., shallow and deeper chemistry may be different for different chemicals). In drainages and drainage banks, shallow soil conditions are considered representative of this dynamic system through time. At SSFL, in areas where facilities have been constructed, there also has been documented soil mixing with depth. Geographic evaluation tools: GIS (digital elevation model, topographic maps, and geologic maps) and field reconnaissance to evaluate potential off-site sampling with physical characteristics similar to SSFL and meet other study criteria (e.g. distant sites to address public concerns as described above). Naturally-occurring and anthropogenic ambient chemicals: These chemicals may occur naturally or be present due to human activities in undeveloped off-site CBRAs. The target analytes include metals, hexavalent chromium, fluoride, polychlorinated dioxin/furans, chlorinated pesticides/herbicides, polycyclic aromatic hydrocarbons (PAHs), perchlorate, and phthalates. Of these, the organic chemicals result from surficial deposition processes (e.g., airborne transport and deposition of wildfire ash or aerial spraying of pesticides), while the inorganic constituents result from both surficial deposition processes (e.g., airborne transport of lead from leaded gasoline) and soil development processes related to the underlying parent bedrock material. Current SSFL environmental program requirements: The chemical soil background data may be compared between the strata (defined above) and previously-collected on-site characterization data. Therefore, the chemical soil background data should be collected consistent with current field methods, including grain-size analysis as a comparison parameter. Information Basis to Guide Decision Making: Confidence Goal: A high level of confidence is needed for the chemical soil background dataset and the resulting background statistic that will be used for SSFL characterization sampling and cleanup decisions. A background statistic that may be used is the 95% upper tolerance limit about the 95 th percentile (95/95 UTL). Therefore, the Krishnamoorthy and Mathews (2009) non-parametric method was used to determine the sample size needed to achieve a 95/95 UTL; the minimum sample size was determined to be 59 samples. This sample size target is rounded up to samples for each stratum (see below) to achieve equal shallow and deep sample counts. Page 2 of 6

3 Stratum Definition: The term stratum is used in this context as a sampling and statistical evaluation group, not its geologic meaning. It is the smallest soil comparison group for evaluation in the chemical soil background study that may be used for SSFL characterization and cleanup decisions. It is expected that background data may be compared to on-site data, using strata combinations as well as individual stratum. Background Data Evaluation and Use: The DEP will be prepared by DTSC following issuance of this Sampling and Analysis Plan (SAP) for public review and comment. The DEP will develop and describe criteria for background data usability, acceptability, and application for SSFL decision making. Identify Appropriate Sampling and Analysis Methods: Analytical Requirements: Analytical methods and reporting limits to support chemical background dataset use for SSFL decision-making will be defined in a Quality Assurance Project Plan (QAPP) Addendum. Field Sampling Requirements: Stratified, random sampling strategy in the CBRAs meeting general study criteria for SSFL representativeness. Defined in the SAP and Field Standard Operating Procedures (SOPs). 4. Define the Boundaries of the Study Specifying the Target Population: Population Characteristics: New soil/sediment data are to be collected in a stratifiedrandom manner and in sufficient quantities of samples to achieve a minimum of a 95/95 UTL (per stratum): Sample Population (Strata) Non- Santa Susana Non- Santa Susana Combined Non- Combined Analysis Formation Topography Depth Inorganic Non- Surface & Subsurface Number of Samples (30 Surface; 30 Subsurface) Inorganic Surface Surface Inorganic Santa Susana Non- Surface & Subsurface (30 Surface; 30 Subsurface) Inorganic Santa Susana Surface Surface Organic Organic & Santa Susana & Santa Susana Non- Surface Surface (30 ; 30 Santa Susana) (30 ; 30 Santa Susana) Page 3 of 6

4 Specifying Spatial and Temporal Boundaries and Constraints: Spatial Boundary: Sampling locations as close as possible to the SSFL to be representative of site soil conditions, but sufficiently distant to address public concerns regarding potential airborne impacts from SSFL operations. Spatial Boundary: bank widths are defined as a maximum 15 feet on either side of the channel centerline; to be defined in the field using professional judgment. Spatial Boundary: The CBRAs will be bounded and mapped using property lines, accessibility, and knowledge of the background study area use(s). Collocated surface and subsurface sampling locations: Surface samples will be analyzed for organic and inorganic chemicals, with subsurface samples analyzed only for inorganic constituents. Temporal Boundary: Sample staking in March-April 2011; sample collection in May-June Scale of Decision: Natural off-site areas that are representative of SSFL site characteristics (geology, landform types, recent wildfire histories) and undisturbed by localized human activities (i.e., roads, debris areas, etc.). Practical Constraints: Potential impediments to sample collection (e.g., site access, health and safety issues, soil availability). Random Sample Locations: Within the CBRAs, identify randomly-selected sampling locations based on the four strata Formation s, Formation Non-s, Santa Susana Formation s, and Santa Susana Formation Non-s. Specifying the Sampling Unit for Decision-Making: The sampling unit for SSFL decision making will depend on the scale of the decision to be made. Decision-making will use background data representative of on-site conditions. Thus, the strata defined above may be used in combination or individually to make decisions, depending on what soil characteristics are present. The smallest sampling units that may be the basis for decision-making are the four strata described above. 5. Develop the Analytic Approach Specify Population Parameter(s) or Action Levels to be used for decision(s): Several key decisions must be made during the collection, evaluation, and use of the soil background data. The parameters that will be used in these decisions include: SSFL site characteristics (e.g. geology, landform types, recent wildfire history). Analytical reporting limits and quality assurance / quality control (QA/QC). Statistical confidence to be used in statistical testing. Specify the Decision Rule(s) to be used to address the Problem Statement: If a potential background reference area meets general study criteria for SSFL site characteristics and has not been disturbed by obvious human activities (i.e., roads, etc.), then it should be considered as a CBRA. If an analytical laboratory will meet the study s reporting limit goals and has preselection audit acceptable findings, then it should be considered as a candidate Page 4 of 6

5 laboratory for use in the chemical soil background study. Note: decision rules for data evaluation steps and criteria for usability, acceptance, and application of the background data will be developed and described in the DEP. 6. Specify Performance or Acceptance Criteria Specify Acceptance Criteria: Areas potentially disturbed by localized human activities in the CBRAs will be identified using historical records (e.g., aerial photographs, maps, etc.), then visually during site reconnaissance and sampling visit(s). Sampling design and laboratory measurement and analysis variability will be monitored by collecting a sufficient amount of QA/QC samples (i.e., splits, equipment rinsate blanks, duplicates, and matrix spike/matrix spike duplicates). Specific acceptance criteria are listed in the QAPP appended to this SAP. While the goal is samples per stratum, unforeseen conditions may be encountered that limit sample collection or the number of sample results that are deemed acceptable based on data validation. If encountered, any limitations will be documented and described in the Chemical Soil Background Study Results Report. Specify Statistical Performance Criteria: Note: as described above, the DEP will contain the details of the statistical performance criteria that may be used in the evaluation of the new background dataset. Basic criteria include: The minimum statistical parameter for background stratum data may be based on a 95/95 UTL, assuming that 59 samples (minimum) per stratum are collected. Statistical confidence of 95% may be used in statistical tests. 7. Develop the Plan for Obtaining Data Develop the Sampling and Analysis Design: Details of the sampling plan are provided in the SAP. However, key steps include: Select CBRAs that meet general criteria for representativeness of SSFL site characteristics. Use a systematic design to bound potential sampling locations (e.g., grid overlay, drainage transects), then randomly select sampling locations within those boundaries (or along transect). If a sample location is infeasible (e.g., due to a rock outcrop) a new location will be randomly selected 2,3. Collect the required number of samples in each stratum and document field conditions of sampling (soil type, depth, etc.). Perform the laboratory analyses for the required analytes and review and validate the sampling data. Develop the Sampling and Analysis Plan: The SAP will consist of the following components: o Field Sampling Plan describes the data quality objectives, sampling design of samples per stratum, and field and laboratory methods for the study. o Quality Assurance Project Plan describes analytical methods and reporting limits, QA/QC procedures and acceptability criteria, and data validation Page 5 of 6

6 o o requirements for the study. Field Sampling Standard Operating Procedures describes field sampling methods consistent with on-site soil sampling procedures. Health and Safety Plan describes health and safety requirements and procedures to be used during sampling (to be prepared by contractor doing the fieldwork). Provide planning documents to public and other stakeholders for review and comment, address comments, and modify documents as warranted. Notes: 1 The term strata is used in this context as a statistical evaluation group, not as a geologic reference. 2 Random sampling is used because judgmental sampling does not allow the level of confidence (uncertainty) of the investigation to be accurately quantified, and judgmental sampling introduces bias that limits the statistical inferences that can be applied (U.S. Environmental Protection Agency, 2002b). 3 Additional information on the field sampling design is provided as SAP Appendix A. Krishnamoorthy, K., and T. Mathew Statistical Tolerance Regions: Theory, Applications, and Computation. Hoboken, NJ: Wiley. Page 6 of 6