Contents
... 3.4 Selection of Decision Units   ...
 
... 3.4.1 Decision Unit Designation   ...
 
... 3.4.2 Exposure Area Decision Units   ...
 
... 3.4.3 Spill Area Decision Units   ...
 
... 3.4.4 Subsurface Decision Units   ...
 
... 3.4.5 Perimeter Decision Units   ...
 
... 3.4.6 Stockpile Decision Units   ...
 
... 3.4.7 Sediment Decision Units   ...
 
... 3.4.9 Evaluation of Decision Unit Data   ...
 
... 3.5 Example Decision Units   ...
 
... 3.5.7 Subsurface Decision Units   ...
 
... 3.5.8 Stockpile Decision Units   ...
 
... 3.5.9 Sediment Decision Units   ...
 
... 3-10. Example Spill Area and Exposure Area Decision Units   ...
 
... 3-11. Example Exposure Area Decision Units   ...
 
... 3-17. Decision Unit Designated to Investigate PCB Contamination Beside Former Transformer Pad ...
 
... 3-19. Decision Units for a Former Pesticide Mixing and Storage Area ...
 
... 3-20. Spill Area Decision Units Designated Beneath Pesticide Mixing and Storage Tank ...
 
... 3-21. Decision Units to Investigate a Proposed, Four-Acre Hotel Site ...
 
... 3-25. Grouped Lots for Decision Units at a Proposed Residential Site   ...
 
... 3-35. Decision Units Designated for Characterization of Arsenic-Contaminated Sediment in an Estuary ...
 

Figures
... 3-8 Model/example of Exposure Area Decision Units   ...
 
... 3-9 Decision Unit to Investigate Suspected PCB Spill ...
 
... 3-10 Decision Unit for Large Agricultural Site   ...
 
... 3-11 Decision Units at an Industrial Site   ...
 
... 3-12 Former and Planned Uses as Bases for Decision Units   ...
 
... 3-13 Example Neighborhood-Scale Decision Units   ...
 
... 3-14 Example Lot Scale Decision Units   ...
 
... 3-15 Hypothetical Lot-Size Decision Units   ...
 
... 3-16 Grouped Lots for Decision Units at a Proposed Residential Site   ...
 
... 3-17 Decision Units to Investigate a Contaminated Commercial ...
 

3.2 Systematic Planning Of Site Investigation
...are modified and expanded in this guidance in order to incorporate the concepts of "decision units" and the collection of representative samples at the beginning of the process. This more ...
 
...of field activities should be an essential part of all site investigations. Decision Units and Decision Statements are established up front to reflect the desired end use of the ...
 
...instead are to be applied to the mean contaminant concentration within the targeted, decision unit. In general, contaminants in soil, water, soil gas or indoor air at ...
 
...prior to the initiation of site activities. Step 4—Define the Decision Units Steps 1-3 above will help to make a judgment call on how to best establish ...
 
...a laboratory for analysis. In some cases, an entire site can be defined as a single decision unit; however, it is more typical to divide a site into multiple decision units based on known ...
 
...however, it is more typical to divide a site into multiple decision units based on known or suspected spill areas or areas where workers or residents are exposed ...
 
...exposed to soil on a regular basis. A more detailed discussion of the selection of decision units is provided in Subsection 3.4. The size and shape ...
 
...in Subsection 3.4. The size and shape of a decision unit will depend on the specific, potential environmental hazards posed by the target COPCs, ...
 
... actions. Known or suspected spill areas should in general be treated as individual decision units. Spill area DUs are typically very small, ranging from a few hundred square feet to a ...
 
...environmental hazards posed by the target COPCs? How should the decision units be defined to evaluate these potential hazards and associated risks? ...
 
... Develop decision statements using sampling information identified in Step 3 and the decision unit boundaries defined in Step 4. Specify contaminants to be measured and action levels to ...
 
...are often phrased in the form: IF the concentration of [chemical] for the targeted decision unit based on [Multi Increment sampling methods] and analyzed using [analytical method] ...
 
... As described in Section 4, HDOH strongly encourages the use of Multi Increment and decision unit strategies to enhance sample representativeness in the investigation of contaminated soil ...
 
...the representativeness of contaminant concentrations for targeted areas. Selection of decision units is discussed in Step 4, as well as in Subsection 3.4. A comparison of discrete ...
 
...the site prior to finalization of the Sampling and Analysis Plan. Final selection of decision units and collection of samples is dependent on a multitude of site-specific factors, including ...
 
...sample variance from the mean. Good professional judgment is essential when selecting decision units for the site investigation. After the environmental data are collected, the data must ...
 
...water) over a specified area and volume of that media. The latter, referred to as the decision unit, is tied in part to the specific environmental hazard under investigation (Subsection ...
 

3.3 Conceptual Site Models
...summary figures with areas above EALs highlighted (preferably based on decision unit and Multi Increment sample data); Groundwater contamination summary ...
 

3.4 Selection Of Decision Units
... ' 3.4 SELECTION OF DECISION UNITS A decision unit (DU) is an area where a decision is to be made regarding ...
 
... A decision unit (DU) is an area where a decision is to be made regarding the extent and magnitude of contaminants ...
 
...of samples that might have been collected under past approaches. Decision units can be designated for characterization of surface soils and/or subsurface soils. Designation ...
 
... Figure 3-10. Example Spill Area and Exposure Area Decision Units Establishing ...
 
... Soil and Groundwater (HDOH 2016). 3.4.1 DECISION UNIT DESIGNATION The designation of DUs for characterization is unique to ...
 
...under investigation (see Step 8 in Subsection 3.2 and Section 13). Decision units generally fall into two categories (Figure 3-10): 1) Spill Areas, and 2) Exposure Areas. ...
 
... with them. 3.4.2 EXPOSURE AREA DECISION UNITS ...
 
... Figure 3-11. Example Exposure Area Decision Units  Figure shows areas where residents or workers may be exposed to contaminants ...
 
...exposure area is the home range. The size & shape of exposure area decision units depends on the targeted receptor and the desired scale of the evaluation. ...
 
... In the absence of a known or suspect spill area, the most appropriate Decision Unit for relatively immobile contaminants that primarily pose direct-exposure, toxicity-based ...
 
... Examples of DUs based on exposure areas are included in Subsection 3.5. Decision units based on exposure areas can also be established for ecological risk assessments. Additional ...
 
...areas can also be established for ecological risk assessments. Additional guidance on decision units for ecological risk assessments will be included in the TGM in the future. ...
 
...be included in the TGM in the future. 3.4.3 SPILL AREA DECISION UNITS For use in this guidance, a "spill area" is defined as a discernable ...
 
...a dramatic increase in the average concentration of a contaminant across the DU(s). Decision units for these types of spill areas as well as other examples are described in ...
 
... 3.4.4 SUBSURFACE DECISION UNITS A similar approach should be followed for designation of subsurface ...
 
...the effectiveness of cleanup actions. 3.4.5 PERIMETER DECISION UNITS "Perimeter DUs" are established immediately outside an area of suspected ...
 
... within the DUs is completely removed. 3.4.6 STOCKPILE DECISION UNITS Decision unit designation and sampling strategies specific to stockpiles ...
 
... Decision unit designation and sampling strategies specific to stockpiles is provided in the HEER Office ...
 
...to the initiation of site activities. 3.4.7 SEDIMENT DECISION UNITS Detailed guidance on the designation of decision units for sediment ...
 
... Detailed guidance on the designation of decision units for sediment investigations is forthcoming. Sediment is defined as unconsolidated material ...
 
...should focus on migration pathways from suspected source areas to depositional areas. Decision unit sizes and boundaries should be adjusted to address ecological impact concerns and optimization ...
 
... former buildings, suspect dump areas, etc.). Decision units should be designated to characterize the site. Areas of suspected or known heavy contamination ...
 
...criteria will not be met if the highest mean concentration of just one of the 59 decision units exceeds the applicable target action level. Additional sampling would typically be required ...
 
...approaches should be discussed with HDOH on a case-by-case basis. Decision Units should be placed in a systematic random fashion, and with consideration to adequately ...
 
... terrain, soil type, etc.). 3.4.9 EVALUATION OF DECISION UNIT DATA As discussed in Section 5, Multi Increment samples are ...
 
...with Contaminated Soil and Groundwater (HDOH 2016). When using a Decision Unit strategy, the entire area of a Decision Unit is acted upon as a single entity based on ...
 
...strategy, the entire area of a Decision Unit is acted upon as a single entity based on the average contaminant data collected from that ...
 
...If the data indicate that remediation is required, this applies to the entire Decision Unit. If the outcome is "not contaminated," then the entire area of the DU is treated as being ...
 
...treated as being not contaminated. As discussed above, this makes the designation of Decision Units very important to ensure that appropriate exposure areas and/or spill areas are identified, ...
 

3.5 Example Decision Units
... ' 3.5 EXAMPLE DECISION UNITS This Section provides example decision units for commercial/ industrial, ...
 
... This Section provides example decision units for commercial/ industrial, residential, school, large area, subsurface, stockpile, and ...
 
...stockpile, and sediment sites. Examples of both exposure area and spill area decision units are included. A mixture of both types of decision units is often appropriate. The examples ...
 
...are included. A mixture of both types of decision units is often appropriate. The examples provided are based in part on site investigations in ...
 
...a simple spill area DU placed around a former transformer pad. The purpose of the decision unit is to investigate the presence or absence of PCB-contaminated soil in the immediate vicinity ...
 
... Figure 3-17. Decision Unit Designated to Investigate PCB Contamination Beside Former Transformer Pad ...
 
...for the current, commercial use of the property. Decision units designated for a former agricultural, pesticide storage and mixing area are depicted in ...
 
...(red), Exposure Area (blue), and Perimeter Area (blue, outside ring) Decision Units for a Former Pesticide Mixing and Storage Area ...
 
... Figure 3-20. Spill Area Decision Units Designated Beneath Pesticide Mixing and Storage Tank ...
 
...with the pesticide mixing area has been adequately defined (refer to Figure 3-19). Decision units in the outer ring (not depicted) are tested as needed if samples from an inner ring DU ...
 
... Figure 3-21. Decision Units to Investigate a Proposed, Four-Acre Hotel Site DUs A through C represent ...
 
... carried forward as an example in Section 13. Figure 3-21 depicts Decision Units for a proposed commercial development on a four-acre site known to be contaminated with ...
 
...commonly in open areas in the yard. Figure 3-22 depicts typical decision unit designations to investigate these potential concerns. A narrow DU (or DUs) is designated ...
 
... Figure 3-25. Grouped Lots for Decision Units at a Proposed Residential Site Exposure area DUs for a former golf course ...
 
...4.2.8.2 and Section 5). 3.5.7 SUBSURFACE DECISION UNITS Figure 3-29 depicts designation of a thin horizon that represents ...
 
...locations for all or select DU layers. 3.5.8 STOCKPILE DECISION UNITS ...
 
...pertaining to sampling of stockpiles. 3.5.9 SEDIMENT DECISION UNITS The size of sediment DUs will vary widely depending on the nature ...
 
... Figure 3-35. Decision Units Designated for Characterization of Arsenic-Contaminated Sediment in an ...
 
... or in stockpiles after dredging, as discussed in Subsection 3.5.7. Decision unit area and volume designation is based on targeted contaminants of concern and related environmental ...
 

3.6 Sampling And Analysis Plans
... The HEER Office strongly encourages the use of Multi Increment/Decision Unit strategies to investigate contaminated soil. Multi Increment samples are collected using ...
 
...air is presented in Sections 5, 6, and 7, respectively. The application of Decision Unit approaches is recommended for characterization of sediment and surface water as well as soil. ...
 

3.9 Site Investigation Reports
... Site investigation objectives (including DQO) Selection of Decision Units, including replicates Figures displaying all DU locations ...
 

4.0 Decision Unit And Multi Increment Sampling For Soil And Sediment Characterization
... ' SECTION 4 DECISION UNIT CHARACTERIZATION Interim Final - August, 2016 ...
 

Contents
... 4.0 Characterization of Decision Units   ...
 
... 4.3.2 Designation of Decision Units   ...
 
... 4-8 Example Decision Units (a and b)   ...
 
... 4-1 Approximate Increment Spacing for Decision Unit Area (see Equation 1)   ...
 

4.0 Characterization Of Decision Units
... ' 4.0 CHARACTERIZATION OF DECISION UNITS Section 3 discusses the importance of Decision Unit (DU) designation as part ...
 
... Section 3 discusses the importance of Decision Unit (DU) designation as part of the Systematic Planning process of an environmental investigation. ...
 
...overview of sampling theory and �incremental sampling� methods as well as examples of Decision Unit designation under different site scenarios. The document is especially strong in laboratory ...
 
...of representative data and should not be used for final decision making purposes. Decision Unit and Multi Increment sampling methods are not simply �another tool in the toolbox�. This sampling ...
 

4.1 Sampling Theory And Variability Of Contaminant Concentrations In Soil
...area and volume of soil for decision making is determined as part of the Decision Unit designation process (e.g., spill area or exposure area DUs; see Section 3). ...
 
...2) Sample collection methods, 3) Sample processing methods and 4) Analytical error. Decision units and Multi Increment sampling methods are used to minimize and evaluate these potential ...
 

4.2 Use Of Multi Increment Samples To Characterize DUs
...number of small "increments" of soil from multiple locations within the targeted Decision Unit (DU). Multi Increment samples improve the reliability of sample data by reducing the variability ...
 
...relevant information and choosing DUs where COPCs will be representatively sampled. Decision units represent the desired scale of mean contaminant concentration for decision making. As ...
 
... Figure 4-8a. Example Decision Units (see also Section 3.4) DU for spill area contaminated with lead. Flags represent ...
 
... Figure 4-8b. Example Decision Units DU for hypothetical, residential lot on former agricultural land. Rows and ...
 
...mass of the Multi Increment samples collected are not dependent on the size of the decision unit. If the decision unit is the size of a small backyard garden suspected to be impacted by ...
 
...If the decision unit is the size of a small backyard garden suspected to be impacted by sprayed pesticides, ...
 
...pesticides, then a minimum of 30 increments of similar mass is collected. If the decision unit is a 10-acre former field likewise suspected to be impacted by sprayed pesticides, then ...
 
...is known or suspected (refer to Section 7). Decision Unit and Multi Increment sampling approaches should be used to characterize soil for volatile ...
 
...In some cases each side wall and floor of an excavation area may be separate Decision Units, or the floor of an excavation could be divided into more than one Decision Unit to evaluate ...
 
...or the floor of an excavation could be divided into more than one Decision Unit to evaluate a more specific area where contamination may have migrated. In other cases, ...
 
...In other cases, certain side walls or all the side walls maybe combined into a single Decision Unit. The rationale for selecting DUs within an excavation should be clearly addressed in the ...
 
... 4.2.8.2 COLLECTION OF SUBSURFACE MULTI INCREMENT SAMPLES Decision Unit designation for subsurface soil is discussed in Section 3.4.4. A detailed discussion ...
 
..."increment" for the DU layer, identical to increments collected from a surface soil decision unit. Use of a direct-push rig allows collection of continuous cores and collection of the full ...
 

4.3 Use Of Discrete Samples
...discrete sample data. 4.3.2 DESIGNATION OF DECISION UNITS In spite of the limitations noted above, tight grids of discrete sample ...
 

4.4 Common DU-MIS Investigation Mistakes And Problems
... 4.4.1 INAPPROPRIATELY SIZED DUs The designation of Decision Units for site characterization is discussed in Section 3.4. It is important to ensure ...
 
...to ensure that DUs are appropriately sized to meet site investigation objectives. Decision Units should ultimately be sized to address potential environmental hazards posed by contaminants ...
 
...of inappropriately small DUs can also interfere with an efficient site investigation. Decision unit sizes are guided by the need to address risk and optimize remedial efforts. While a strong ...
 
...the gross recognition of large contaminant patterns (see HDOH 2015b). Decision Unit layers, rather than single horizons should be designated and targeted for characterization ...
 
...�sample areas� or �contaminated zones,� referred to in HDOH guidance as �Decision Units (DUs)� represents a composite sample. This can lead to a potential dilution ...
 
...3 of HDOH Technical Guidance Manual for information on designation of Decision Units at contaminated properties. ...
 

Contents
... 5.1.1 Decision Unit Designation   ...
 
... 5-48. Demarcation of Decision Units and DU Information Using a Google Earth Image ...
 

5.1 Initial Site Inspection
...These topics are discussed in detail in the following sections. 5.1.1 DECISION UNIT DESIGNATION Designation of Decision Units (DUs) for characterization is an important ...
 
...DESIGNATION Designation of Decision Units (DUs) for characterization is an important part of the initial site investigation process ...
 
...is an important part of the initial site investigation process (see Section 3). Decision Unit locations are based on the site history and known or suspect areas of contamination. ...
 

5.4 Subsurface Soil Sample Collection
... 5.4 SUBSURFACE SOIL SAMPLE COLLECTION Designation of Decision Units for the collection of subsurface Multi Increment samples is discussed in Section 3.4."Subsurface" ...
 

5.7 Sediment Sampling
...will be expanded in the future to include more detailed information. Well-thought-out Decision Units and investigation objectives are required for sediment investigations in the manner ...
 

5.8 Field Documentation
... etc; Decision Unit coordinates (e.g., latitude and longitude of DU corners); ...
 
... Figure 5-48. Demarcation of Decision Units and DU Information Using a Google Earth Image ...
 
...Positioning System (GPS) equipment is acceptable to record the boundaries of Decision Units (e.g. four corners of a rectangular-shaped Decision Unit). The accuracy of the equipment ...
 
...(e.g. four corners of a rectangular-shaped Decision Unit). The accuracy of the equipment to be used should be documented in the SAP. Any potential ...
 

7.5 Soil Vapor Or Indoor Air Sampling Methods
...underestimation of representative concentration of a chemical in soil within a targeted, “Decision Unit” area. The effect of subsurface heterogeneity on the representativeness of soil vapor samples ...
 
...small number of samples collected in the field, and the lack of well-thought-out Decision Units in soil vapor investigations typically means that the maximum concentration of a chemical ...
 

7.6 Soil Vapor Sample Collection Procedures
...soil vapors (see Section 7.2). The HEER Office is investigating the use of Decision Unit (DUs) and Multi-Increment Sample (MIS) approaches to obtain more representative data and better ...
 
...establish site investigation objectives (refer to Sections 2 and Section 3). Decision Units designated for vapor intrusion would necessarily be tied to the footprint of existing or future ...
 

7.8 Soil Vapor or Indoor Air Sample Analysis
...intrusion studies. One evolving approach is to subdivide a site into targeted Decision Units (DU) for screening characterization. Active soil vapor sampling will be targeted for the ...
 
...is the ability to collect and then combine multiple samples within individual, targeted Decision Unit areas for comparison to adjacent areas or for estimation of time-averaged VOC concentrations ...
 

9.1 Pesticide Contamination at Former Agricultural Facilities and Sites
... level investigations above laboratory reporting limits (e.g., neighborhood-size decision units) should be carried forward in more detailed investigations (e.g., lot-size decision units). ...
 
...should be carried forward in more detailed investigations (e.g., lot-size decision units). Refer to Section 3 and Section 4 for additional information on sampling decision units ...
 
...Refer to Section 3 and Section 4 for additional information on sampling decision units and sampling strategies. Table 9-2 Summary of Target Pesticide ...
 
...in abandoned, former mixing areas above levels of potential concern. Full testing of Decision Units within a former pesticide mixing area most suspected of heavy contamination is recommended. ...
 

Figures
... 4-1 Example Decision Units   ...
 
... 4-14 Multi-Increment Decision Units Chosen with Use of Initial Discrete Sampling Data ...
 

10.3 Data Quality Assurance Procedures
... Soil replicates/ triplicates Depends on numbers of Decision Units (DU), COPCs, site characteristics. See Section 4.2.3 regarding field replicates (triplicates ...
 

10.6 Field QA/QC
...replicate samples are duplicate or triplicate samples collected from within the same decision unit or from the same groundwater well to evaluate the precision of the sampling effort. Replicates ...
 
... activity (e.g., replicates provide a measure of contaminant heterogeneity for a specific decision unit). If the degree of contaminant heterogeneity exceeds established DQO in the SAP, then additional ...
 
...whichever is greater. At least 10% replicate QA/QC samples should be collected in each decision unit or each area of known or suspected contamination. Consider both the horizontal and vertical ...
 
...data to applicable HEER Office EALs (See Section 4.2.5). The number of decision units where Multi-Increment sample replicates are collected will vary with each project, total number ...
 
...approach (similar to that used in the lab) may be applied in the field, if multiple decision units are similar (e.g., similar soil type, contaminants of concern, history of chemical use, topography, ...
 
... deviation are used to calculate, with 95% confidence, the mean value for the individual decision unit. Formulas and spreadsheets for calculating the 95% UCL are available through websites providing ...
 

13.5 STEPS TO ENVIRONMENTAL HAZARD EVALUATION
... As discussed in Sections 3 and Section 4, sites should be subdivided into individual decision units (DU) and the representative concentration of target COPCs within each DU determined. For groundwater ...
 
...sample data to evaluate direct exposure concerns in targeted decision units �    ...
 
...areas. For large, industrial complexes, the property may need to be divided into smaller decision units based on specific exposure areas (e.g., specific work areas at an industrial site). The use ...
 
...are identified then specific spill areas should be identified and treated as separate decision units. This is because the spill area, not the site as a whole, is the target where the "receptor" ...
 

15.5 Site Assessment Process
...sampling at release sites demonstrate that contamination in areas of concern (i.e. decision units) are below the EALs, then a more comprehensive assessment or additional evaluation is not ...
 

Appendix 15-C Frequently Asked Questions
...the art sampling protocols, like Multi-increment sampling(MIS) & use of Decision Units (DUs)? Previous sample results will ...
 

16.4 Implementing the Cleanup Remedy Selected
...be conducted when remedial actions are complete, including the selection of appropriate decision units and the collection of field replicates to demonstrate the precision of confirmation testing. ...
 

18.5 Document Outlines
... 4.4 Define the Decision Units   ...
 
... 4.0 Decision Units 5.0 ...
 
... 5.2 Decision Units for Confirmation Sampling   ...
 

Log of TGM Updates
... 4 Decision Unit Characterization Aug, 2016   ...
 
...   Use of Decision Unit and Multi-increment Soil Sample Investigation Approaches to Characterize a Subsurface ...
 
...   Technical Guidance Manual Notes: Decision Unit and Multi-increment Sample Investigations. Mar 25, 2011 ...
 

PDF Download Page
...   Use of Decision Unit and Multi-increment Soil Sample Investigation Approaches to Characterize a ...
 
... Technical Guidance Manual Notes: Decision Unit and Multi-increment Sample Investigations. ...
 

Additional Guidance Documents" Language="VB" MasterPageFile="~/lib/Content.master
... March 2011 Use of Decision Unit and Multi-increment Soil Sample Investigation Approaches to Characterize a ...
 
...at a site on Hickam Air Force Base, O`ahu was investigated using Decision Unit (DU) and Multi-increment Sampling (MIS) techniques. 29 borings were installed ...
 
... Technical Guidance Manual Notes: Decision Unit and Multi-increment Sample Investigations. A compilation ...
 
... A compilation of notes and recommendations for Decision Unit (DU) and Multi-increment Sampling (MIS) site investigations. ...
 

7.10 Documentation of Soil Vapor or Indoor Air Sampling
... error. This is relatively straight forward for soil investigations, where a designated Decision Unit (DUs) is subsampled by collection of a single, multi-increment sample (refer to Section 7.6.2.2 ...
 
...and 5). Replicates are collected to verify that the number of increments collected in the Decision Unit, typically thirty to fifty, adequately capture the contaminant heterogeneity and provide a ...
 

13.7 HUMAN HEALTH RISK ASSESSMENTS
...of COPCs. It is important to remember that COPCs may be uniquely selected for individual decision units (see Section 3.6). In addition, COPCs may be uniquely selected for each environmental ...
 
...evaluation of soil data to estimate representative contaminant concentrations within decision units (including exposure point concentrations for evaluation of direct-exposure hazards) is discussed ...
 
...of approaches to determine average contaminant concentrations for exposure areas or decision units is presented in Sections 3 and Section 4 . The final step in the exposure ...
 
...site and used for comparison to the HDOH Tier 1 EALs. If a given site has more than one decision unit, exposure point concentrations must be developed for each decision unit. Statistical approaches ...
 
...exposure point concentrations must be developed for each decision unit. Statistical approaches are generally necessary to determine the exposure point concentrations. ...
 
...sampling strategy is used to collect samples, replicate samples from the same decision unit allow for statistical calculation of several important quantities, including the standard deviation, ...
 
...are 95% confident does not exceed the true mean of the population (e.g., in an individual decision unit). To calculate the 95% UCL for multi-increment sample (MIS) data, three or ...
 
...of use, etc. such as former agricultural fields for a particular crop/area). If the decision units are heterogeneous in key physical characteristics, contaminant sources, or history of use, ...
 
...contaminant sources, or history of use, triplicates must be collected from each decision unit to calculate a 95% UCL for each decision unit. When the DU replicate data ...
 
... to calculate a 95% UCL for each decision unit. When the DU replicate data meet an initial data quality measure for relative standard ...
 
...sampling strategies to establish representative soil contaminant concentrations for decision units. When using a discrete sampling strategy, sample locations should be randomly selected within ...
 
...a discrete sampling strategy, sample locations should be randomly selected within the decision unit; and effort should be made to maximize the number of discrete samples collected within each ...
 
...effort should be made to maximize the number of discrete samples collected within each decision unit (30 or more discrete samples from each decision unit would be best, or as close to this number ...
 
...(30 or more discrete samples from each decision unit would be best, or as close to this number as feasible). A statistical derivation ...
 
...should not be included in estimation of exposure point concentrations. Instead, use decision unit strategies to divide the site and group data points prior to calculating exposure point concentrations ...
 
...concentrations (see Sections 3 and Section 4 for more information regarding decision units). For residential land use scenarios, sample data should not be averaged over areas greater ...
 

8.0 FIELD SCREENING METHODS
...general magnitude of contamination in order to assist in initial site evaluation and Decision Unit (DU) designation for more detailed characterization; Rapid identification for ...
 

8.4 FIELD SCREENING METHODS FOR SELECT CONTAMINANTS AND MEDIA
...as well as matrix interferences (refer to Section 4.1.2). A Decision Unit (DU) should be designated for a specific area of interest (e.g., suspect Spill Area ...