8.0 INTERPRETATION OF RESULTS
The intent of the data is to make a decision to reject or not reject the null hypothesis and determine if the survey unit meets the release criterion. Once the data has been collected on a survey area, the sample mean, standard deviation and median shall be calculated. The median is the middle value of the data set when the number of data points is odd, and is the average of the two middle values when the number of data points is even. If there are no values above the DCGLw the survey unit meets the release criterion.
8.1 Soil Samples
If the survey unit has all soil sample measurements less than the DCGLw the survey unit meets the release criterion. If the average of all soil sample measurements is greater than the DCGLw the survey unit does not meet the release criterion. If any soil sample measurement is greater than the DCGLw a Sign test shall be conducted along with an elevated measurement comparison. The Sign test is applied as follows:
1. List the survey unit result measurements, Xj, with j = 1, 2, 3, . . ., N
2. Subtract each measurement, Xj, from the DCGLw to obtain the differences:
Dj = DCGLw - Xj, I = 1, 2, 3, . . . , N
3. Discard each difference that is exactly zero and reduce the sample size, N, by the number of such zero measurements.
4. Count the number of positive differences. The result is the test statistic, S+. Note that a positive difference corresponds to a measurement below the DCGLw and contributes evidence that the survey unit meets the release criterion.
5. Large values of S+ indicate the null hypothesis is false. Compare the value of S+ with the critical values in Table I.3 of Reference 2.1. If S+ is greater than the critical value, k, in the table, the null hypothesis is rejected.
When the null hypothesis has been rejected, the soil in the survey unit meets the release criteria and can be managed as clean material. If necessary, the material from a survey unit may be removed and placed in a clean area. This material may be used as backfill in areas that meet the final release criteria without requiring re-survey of the survey unit
8.2 Surface Scans
If, for surface scans, the difference between the largest survey unit measurement and the background is less than the DCGLw the survey unit meets the release criterion. If the difference of the survey unit average minus background is greater than the DCGLw the survey unit does not meet the release criterion. If the difference between any survey unit measurement and background is greater than the DCGLw and the difference of the survey unit average and background is less than the DCGLw, a Wilcoxon Rank Sum (WRS) test shall be conducted along with an elevated measurement comparison. The WRS test shall be applied as described below;
1. Background for surface scans of concrete shall be determined on similar concrete surfaces that have not been impacted by Pu contamination. Similar concrete from a near shelter shall be counted, to proper accuracy (95% confidence level), to determine the background to subtract. Similar materials shall be used to determine the appropriate background.
2. Adjust the background measurement, Zj, by adding the DCGLw to the background measurement, Xj . Zj = Xj + DCGLw
3. The m adjusted background sample measurements, Zj from the background area and the n sample measurements, Yj from the survey unit are pooled and ranked in order of increasing size from 1 to N, where N = m + n.
4. If several measurements are tied (i.e. have the same value), they are all assigned the average rank of that group of tied measurement.
5. If there are t "less than" values, they are all given the average of the ranks from 1 to t. Therefore, they are all assigned the rank t(t+1)/2t, which is the average of the first t integers.
6. Sum the ranks of the adjusted measurements from the background, Wb. Note that since the sum of the first N integers is N(N+1)/2, one can equivalently sum the ranks of the measurements from the survey unit, Ws, and compute Wb = N(N+1)/2 - Ws.
7. Compare Wb with the critical value given in Table I.4 of Reference 2.1 for the appropriate values of n, m, and ". If Wb is greater than the tabulated value, reject the hypothesis that the survey unit exceeds the release criterion.
8.3 Elevated Measurement Comparison
The Elevated Measurement Comparison (EMC) is performed for both direct measurements and scanning measurements. Any measurement from the survey unit that is equal to or greater than the investigation level indicates an area of relatively high concentrations that should be investigated further, regardless of the outcome of the nonparametric statistical tests. Any measurement from the survey unit that is equal to or greater than the DCGLEMC causes the entire survey unit to fail. The release criterion are established for uniform contamination distributed throughout the survey unit and relate the risk or dose to that criterion.
The comparison includes all systematic sampling locations and the flagged or judgmental locations. The derived concentration guideline level for the EMC is:
where Am is the area factor for the area of the systematic grid area derived from Section 5.5.2.4, Reference 2.1. This will establish an a priori limit that relates the DCGLw with the survey design. After surveys have been taken the DCGLEMC can be adjusted to get a value of Am appropriate for the actual area of elevated concentration. If the DCGLEMC is exceeded, the unit under comparison fails the test and the survey unit does not demonstrate compliance with the release criterion.
8.4 Range
The range of the data set should be evaluated by subtracting the minimum from the maximum and dividing it by the standard deviation. This will give a number that represents the range of data in units of number of standard deviations. A range of less than 3 standard deviations is desired. For large data sets the range most likely will be wider. If the range is wider than 3 standard deviations, closer evaluation of the data is appropriate.
8.5 Data Reduction and Review
8.5.1 Processing and Review
Each analyst is responsible for data reduction and review in his/her own area. The data reduction and review process ensures that all procedures pertaining to sample preparation and handling, proper identification of analysis output (charts, graphs, etc), correctness and completeness of all data, adherence to documented SOPs, documentation of abnormalities and the proper format has been used to report all data.
The processing of data, either by manual computation, input of data for computer processing or by direct computer output, will be performed by each analyst. All documentation required for data processing will be provided. All calculations will be performed by analysis-specific SOPs or by validated software programs. The analyst performing the review will complete a data review checklist.
A secondary level of review will also be performed, as per the off-site laboratory's QAMP. This review assesses:
· The acceptability of the data in respect to adherence to analytical SOPs;
· Correct interpretation of results;
· Correctness of numerical input;
· Correct constituent reporting with laboratory qualifiers;
· Correctness of calculations (checked randomly);
· The acceptability of QC data;
· Documentation of instrument function;
· Use of correct standard documentation and dilution factors;
· Assessment of holding times.
The secondary review also ensures that all methods used adhere to the specific project instruction, abnormal events have been identified and corrective actions have been taken, valid interpretations have been made with regard to the initial review and the data package contains all required documents for review and that the data were reported in the proper format. The second level reviewer will sign the data checklist.
A third and final level of review will be conducted to evaluate the completeness of the data package. A review will be made to ensure that all parameters requested have been reported with a value or reporting limit, the correct units and significant figures have been used, all nonconforming events and violations have been evaluated and addressed, and the final report is legible and in proper format.
8.5.2 Data Reporting
Data will be reported in both hard copy and electronically in a CLP-type format. Information in the data package includes; sample results, QC data, raw data for field and QC results and other pertinent information needed for validation. The electronic data will include results for all analyzed samples in a format most commonly used by the off-site analytical laboratory.
8.5.3 Data Management
The off-site analyses to be kept on file include all radiological and chemical data from all samples submitted for off-site analysis. This information will be in hard copy and in an electronic format. Chemical data will be reported in a "CLP-type" format. All other data will be reported in a data package that includes samples results, associated QC data, raw data for all field and QC samples, and all other information needed to recalculate the analytical results as well as perform a complete data validation.
The electronic deliverable format required will be in the following format (Table 8.1), as applicable.
Table 8.1
|
Matrix |
On-Site |
Off-Site |
Hard-Copy |
Electronic |
|
SAMPNUMB |
C |
15 |
0 |
IT sample number |
|
SAMPLEDATE |
D |
8 |
0 |
Date sample was collected |
|
LABSAMPNUM |
C |
10 |
0 |
Lab sample number |
|
DATAGROUP |
C |
10 |
0 |
Lab QC group |
|
PARAMETER |
C |
40 |
0 |
Analyte Name |
|
VALUE |
N |
12 |
2 |
Analyte Value |
|
UNITS |
C |
6 |
0 |
Reported Units |
|
LABQUAL |
C |
6 |
0 |
Lab Qualifier |
|
DETECTLIM |
N |
12 |
2 |
Lab Detection Limit |
|
DATEANALY |
D |
8 |
0 |
Date of analysis |
|
DATEXTRACT |
D |
8 |
0 |
Date of extraction |
|
EXTRMETHOD |
C |
10 |
0 |
Extraction method |
|
ANLSMETHOD |
C |
10 |
0 |
Analytical method |
C = Character Field
N = Numerical Field
D = Date Field
Analyses performed on-site include all radiological and chemical data collected during sample collection and processing. These data will be recorded by radiological subcontractor personnel and kept on file in hard copy and electronically. The same criterion applies for analyzing on-site lab data.
Table 8.2 shows the various types of data that will be generated during remediation of the BOMARC Site. Sample analyses will be conducted both on-site and off-site. Selected portions of the data may be loaded into a database for further processing and statistical analysis-primarily the final status survey soil sample data.
Table 8.2
.....................................Analysis...........................Deliverable.............
|
Field Name |
Type |
Data Length |
Field Decimal |
Description |
|
Air Filters |
X |
. |
X |
X |
|
Wipes |
X |
. |
X |
. |
|
Final Status survey soil |
X |
5% |
X |
X |
|
Excavation pit rad surveys |
X |
. |
. |
. |
|
Excavated soil rad surveys |
X |
. |
. |
. |
|
Road rad surveys |
X |
. |
. |
. |
|
Loading area rad surveys |
X |
. |
. |
. |
|
Shipping container rad surveys |
X |
. |
. |
. |
|
Soil stockpile rad surveys |
X |
. |
. |
. |
|
Equipment rad surveys |
X |
. |
. |
. |
|
PPE rad surveys |
X |
. |
. |
. |
|
Soil stockpile rad analysis |
X |
. |
X |
X |
|
Soil Stockpile Chem. Analysis (when necessary) |
X |
. |
X |
X |
|
Sediment rad analysis |
X |
5% |
X |
X |
|
Surface water |
X |
5% |
X |
X |
|
