As requested by Laura Behjan, assistant city manager for Simi Valley, EnviroReporter.com supplied the city an analysis of elevated Sr-90 readings in the Brandeis-Bardin Institute that were performed in 1995. According to the California Department of Health Services (CDHS), there was only one elevated Sr-90 reading detected at the institute that is between Runkle Canyon and Rocketdyne’s Area IV where nuclear work was done from the 1950s until 1988. Our analysis shows that there are at least 25 soil [readings] with elevated Sr-90 readings.
These elevated readings are included in the 535-page 1995 McLaren/Hart report, Additional Soil and Water Sampling – The Brandeis-Bardin Institute and Santa Monica Mountains Conservancy.
LETTER TO LAURA BEHJAN:
June 11, 2007
Thank you all for the informed discussion today! Following are the sources for my comments/questions about two CDHS’s statements in their April 10, 2007 responses to the City regarding strontium-90 on the Brandeis-Bardin property. This information is provided as a courtesy to the City and to promote a continued open exchange of information as you deal with this issue and I cover it.
Except for one soil sample, CDHS says there’s no evidence of elevated strontium-90 on the land between Runkle Canyon and Area IV of Rocketdyne, Brandeis-Bardin. The implication is that if Brandeis-Bardin has little or no elevated Sr-90, and it’s closer to Rocketdyne, that Runkle Canyon’s high Sr-90 readings are suspicious. Regardless of CDHS’s intention, the department states twice that there is only one sample known of elevated Sr-90 ever found on the Brandeis-Bardin property.
CDHS writes in page 3 of the report: “Additional reasons for the CDHS sampling were: 1) with the exception of one area in a watershed in close proximity to the SSFL site, elevated Sr-90 was not identified in surveys of the Brandeis Bardin property.”
CDHS also writes in page in page 9: “Also, previous surveys of the Brandeis Bardin property, which is located between SSFL Area IV and the Foster Wheeler survey locations on the Runkle Canyon site, including GP-52-M, did not show elevated Sr-90 (with the exception of one surface run-off location in close proximity to SSFL Area IV that averaged approximately 0.1 pCi/g, or less than 1/10 of the average Runkle Canyon Sr-90 sample results and less than 1/100 of the GP-52-M sample results).”
This doesn’t seem to be accurate. Utilizing the normal background of Sr-90 in an area on Runkle, with an average of 0.030 pCi/ of Sr-90 as shown in “Table 8-10 – Radionuclide Results for Soil Samples at the Western Sampling Site” on page 8-21 of the March 10, 1993 “Multi-Media Sampling Report for the Brandeis-Bardin Institute and the Santa Monica Mountains Conservancy – Volume I – Final Report,” available in the Reference section of the Simi Valley Library, there are 25 Brandeis-Bardin soil samples with elevated Sr-90 and 20 if utilizing the CDHS figure for background Sr-90 in the area of 0.052 pCi/g.
These elevated readings are included in the 535-page 1995 McLaren/Hart report, “Additional Soil and Water Sampling – The Brandeis-Bardin Institute and Santa Monica Mountains Conservancy,” which is also in the Simi Valley Library, Reference # R-SV00139.
Following is a list including the approximate page numbers, also referred to by title, in the report and the corresponding Sr-90 readings. These readings are all in pCi/g.
Table 22 (p. 143): 0.06 & 0.05 & 0.09
Table 22 – continued (p. 144): 0.04
Table 25 (p. 148): 0.06
Table 27 (p. 150): 0.04
Table 29 (p. 152): 0.06
Table 32 (p. 156): 0.08 & 0.09 & 0.12 & 0.15
Table 32 – continued (p. 157): 0.08 & 0.11 & 0.19 & 0.15 & 0.24 & 0.14 & 0.15
Table 32 – continued (p. 158): 0.093
Table 35 (p. 164): 0.08 & 0.09 & 0.12
Table 35 – continued (p. 165): 0.061
Table 36 (p. 166): 0.18 & .088
Therefore 25 samples here are above the average background of 0.030 pCi/g. 20 samples here are above the average background of 0.052 pCi/g used by CDHS.
Either way, there are 20-25 areas found in just this one report that cite elevated Sr-90 soil readings in Brandeis-Bardin, not the one referred to twice by CDHS.
I hope you find this helpful.
*November 7, 2015 ADDENDUM:
According to the U.S. EPA’s FINAL TECHNICAL MEMORANDUM LOOK-UP TABLE RECOMMENDATIONS SANTA SUSANA FIELD LABORATORY AREA IV RADIOLOGICAL STUDY on page 19, released November 27, 2012 after the EPA’s $41.5 million radiological study of Area IV, the “Background Threshold Value” (BTV) for Strontium-90 + D (Y-90) is 0.0750 pCi/g. Therefore our amended Sr-90 BTV is 0.0750 pCi/g. Note that this is the background for the substance on the lab proper, not Brandeis-Bardin, making this a conservative higher-than-reality BTV for Sr-90 assessment of the radionuclide samples on Brandeis-Bardin. This conservative determination also includes the “D” part of the substance giving the Sr-90 BTV an even higher level than the one we correctly used in our 2007 letter to the City of Simi Valley.
Using this newer 2012 BTV value for Sr-90 + D, 6 (six) samples from the 1993 McLaren/Hart report were over background. 13 (thirteen) from 1995 McLaren/Hart report were over background. 19 (nineteen) soil samples at the Brandeis-Bardin Institute were over background for Strontium-90 + D.