Classrooms at Palos Verdes High School (PVHS) were found to have the highest indoor radon levels (greater than 30 pCi/L) measured as part of this study. Figure 1 shows a schematic of the school buildings with indications of the range of indoor radon data for the classrooms that were measured. Table 1 lists the results of the gamma-ray measurements. With the exception of the measurement made in the crawl space beneath the 200 Science Wing, all of the measurements have uranium values in the range from 2.3 to 3.7 ppm eU. The measurement in the crawl space gave a value of 12.8 ppm eU which is 4 to 5 times greater than the other measurements. Table 2 lists the results of laboratory measurements made on soil samples. The values for the soil samples taken from the crawl space beneath the 200 Science Wing confirm the relatively high uranium concentrations. At the same time, the much higher concentrations of potassium and thorium of the field gamma-ray measurements are probably caused by materials in the concrete slab of the floor of the building. This is a result of having made the measurement in the crawl space with the gamma-ray detector measuring gamma-ray not only from the soil but also from the building materials. The relatively poor agreement between the in situ measurements at positions 1 and 4 and the laboratory data for the soil samples suggests that the soil samples are not representative of the material measured by the field spectrometer. This can occur if the area measured is not homogeneous. The in situ measurements measured gamma-rays from several tons of soil whereas the soil samples were only a few pounds.
Table 3 lists the indoor radon data measured for classrooms at Palos Verdes High School and the dates and times when the charcoal canisters were put in place and retrieved. The highest radon levels occurred in rooms 209 and 210 and the highest value measured was 86 pCi/L. This high value was, however, measured inside a closed cabinet with pipes entering into it from the crawl space below. The highest value measured in a classroom was 49 pCi/L. Repeat measurements made in a number of classrooms are consistent with earlier measurements. Measurements made in the crawl space beneath the 200 Science Wing gave radon levels greater than 500 pCi/L. Because of the very high levels found in the classrooms of the 200 Science Wing, the PVPUSD took steps to remediate the indoor radon. The remediation technique was done by a contractor and consisted of covering the soil in the crawl space with a thick plastic sheet and pumping air from beneath the plastic sheet to the outside atmosphere. Table 4 lists the results of radon measurements made in the classrooms after completion of remediation. The data in Table 4 show that the remediation reduced the radon concentrations to levels well below the USEPA action level of 4 pCi/L.
Figure 1. Schematic of rooms at Palos Verdes High School showing indoor radon levels and sites at which gamma-ray measurements were made.
Table 1. Results of gamma-ray spectrometer measurements at Palos Verdes High School. Site locations are indicated in Figure 1 (e.g. location number 1 refers to PVHP1). The column labeled "Group" identifies the group to which the measurement was assigned as a result of classification of the gamma-ray data.
|
Location |
K |
eU |
eTh |
Group |
Latitude |
Longitude |
|
|
(%) |
(ppm) |
(ppm) |
|
(degrees) |
(degrees) |
|
PVHP1 |
1.4 |
2.3 |
4.5 |
3 |
33.7805 |
-118.4175 |
|
PVHP2 |
0.9 |
3.7 |
3.7 |
2 |
33.7802 |
-118.4176 |
|
PVHP3 |
1.5 |
3.0 |
3.7 |
3 |
33.7807 |
-118.4181 |
|
PVHP4 |
1.0 |
3.4 |
4.7 |
3 |
33.7798 |
-118.4178 |
|
PVHP5 |
1.1 |
2.6 |
4.3 |
3 |
33.7798 |
-118.4184 |
|
PVHP6* |
2.4 |
12.8 |
5.0 |
4 |
|
|
|
PVHP8 |
0.9 |
3.1 |
3.8 |
2 |
33.7811 |
-118.4180 |
* Measurement was made in the crawl space under the 200 Science Wing.
Table 2. Results of laboratory measurements of soil samples. The K, eU, and eTh concentrations were determined by a laboratory gamma-ray spectrometer and the field results are presented for comparison. Radon emanation fraction was determined as discussed in the section on methodologies.
|
Location |
Laboratory |
Field Spectrometer |
Radon |
Latitude |
Longitude | ||||
|
|
K |
eU |
eTh |
K |
eU |
eTh |
Eman. |
(degrees) |
(degrees) |
|
|
(%) |
(ppm) |
(ppm) |
(%) |
(ppm) |
(ppm) |
|
|
|
|
PVHP1 |
2.3 |
3.2 |
12.0 |
1.4 |
2.3 |
4.5 |
0.11 |
33.7805 |
-118.4175 |
|
PVHP4 |
1.1 |
8.7 |
5.1 |
1.0 |
3.4 |
4.7 |
0.27 |
33.7798 |
-118.4178 |
|
PVHP6a* |
0.6 |
12.5 |
2.5 |
2.4 |
12.8 |
5.0 |
0.20 |
|
|
|
PVHP6b* |
0.6 |
13.2 |
2.5 |
2.4 |
12.8 |
5.0 |
0.18 |
|
|
|
PVHP6c* |
0.8 |
19.6 |
3.2 |
2.4 |
12.8 |
5.0 |
0.19 |
|
|
|
PVHP6d* |
0.8 |
19.4 |
3.0 |
2.4 |
12.8 |
5.0 |
0.16 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Bulk Density (g/cc) |
Water Content |
Porosity |
|
|
| |||
|
PVHP1 |
0.98 |
24.8% |
0.63 |
|
|
| |||
|
PVHP4 |
0.94 |
15.9% |
0.64 |
|
|
| |||
* Samples were taken of soil in the crawl space under the 200 Science Wing. Note that only one field spectrometer measurement was made in the crawl space and samples were not collected at the same location.
Table 3. Results of indoor radon measurements in classrooms. Measurements with the letters "CAB" following the room number indicate that the detector was placed in a cabinet.
|
Room |
Radon |
Start |
Stop |
||
|
Number |
(pCi/L) |
Date |
Time |
Date |
Time |
|
Blank |
0.2 |
15-Feb-03 |
15:25 |
17-Feb-03 |
15:25 |
|
Blank |
0.2 |
23-Feb-03 |
20:53 |
23-Feb-03 |
20:53 |
|
Blank |
0.2 |
16-Mar-03 |
20:05 |
18-Mar-03 |
20:05 |
|
Blank |
0.2 |
28-Mar-03 |
18:19 |
30-Mar-03 |
18:19 |
|
D |
1.9 |
21-Feb-03 |
16:41 |
23-Feb-03 |
17:07 |
|
A |
4.6 |
21-Feb-03 |
16:44 |
21-Feb-03 |
17:06 |
|
G |
1.3 |
21-Feb-03 |
16:38 |
21-Feb-03 |
17:01 |
|
Crawl Space |
589.9 |
14-Mar-03 |
15:47 |
16-Mar-03 |
15:44 |
|
Crawl Space |
544.2 |
14-Mar-03 |
18:46 |
16-Mar-03 |
15:44 |
|
B |
1.9 |
21-Feb-03 |
16:43 |
21-Feb-03 |
17:04 |
|
F |
1.2 |
21-Feb-03 |
16:39 |
21-Feb-03 |
17:01 |
|
201 |
0.3 |
15-Feb-03 |
9:15 |
17-Feb-03 |
9:02 |
|
202 |
1.4 |
15-Feb-03 |
9:16 |
17-Feb-03 |
9:04 |
|
203 |
0.6 |
21-Feb-03 |
16:02 |
23-Feb-03 |
16:03 |
|
203 |
4.5 |
14-Mar-03 |
15:34 |
16-Mar-03 |
15:34 |
|
203 |
3.9 |
14-Mar-03 |
15:35 |
16-Mar-03 |
15:35 |
|
204 |
1.9 |
21-Feb-03 |
16:05 |
23-Feb-03 |
16:05 |
|
204 |
14.0 |
14-Mar-03 |
15:35 |
16-Mar-03 |
15:36 |
|
204 |
12.2 |
14-Mar-03 |
15:37 |
16-Mar-03 |
15:35 |
|
205 |
3.9 |
21-Feb-03 |
16:09 |
23-Feb-03 |
16:06 |
|
205 |
25.3 |
14-Mar-03 |
15:38 |
16-Mar-03 |
15:37 |
|
205 |
20.1 |
14-Mar-03 |
15:39 |
16-Mar-03 |
15:37 |
|
206 |
19.2 |
15-Feb-03 |
9:19 |
17-Feb-03 |
9:05 |
|
206 |
18.7 |
21-Feb-03 |
16:12 |
23-Feb-03 |
16:08 |
|
206 |
16.3 |
21-Feb-03 |
16:12 |
23-Feb-03 |
16:08 |
|
206 |
23.4 |
14-Mar-03 |
15:40 |
16-Mar-03 |
15:40 |
|
206 |
27.2 |
14-Mar-03 |
15:41 |
16-Mar-03 |
15:39 |
|
207 |
5.9 |
15-Feb-03 |
9:22 |
17-Feb-03 |
9:07 |
|
207 |
13.2 |
21-Feb-03 |
16:15 |
23-Feb-03 |
16:21 |
|
207 |
13.1 |
14-Mar-03 |
15:43 |
16-Mar-03 |
15:41 |
|
208 |
17.1 |
15-Feb-03 |
9:24 |
17-Feb-03 |
9:09 |
|
208 |
19.4 |
21-Feb-03 |
16:17 |
23-Feb-03 |
16:26 |
|
208 |
3.8 |
14-Mar-03 |
15:50 |
16-Mar-03 |
15:46 |
|
208 |
5.2 |
14-Mar-03 |
15:50 |
16-Mar-03 |
15:46 |
|
208 |
7.2 |
28-Mar-03 |
17:24 |
30-Mar-03 |
17:02 |
|
208 |
8.0 |
28-Mar-03 |
17:51 |
30-Mar-03 |
17:02 |
|
209 |
21.3 |
21-Feb-03 |
16:19 |
23-Feb-03 |
16:31 |
|
209 |
37.2 |
14-Mar-03 |
15:52 |
16-Mar-03 |
15:47 |
|
209CAB |
86.2 |
14-Mar-03 |
15:52 |
16-Mar-03 |
15:47 |
|
210 |
33.2 |
21-Feb-03 |
16:20 |
23-Feb-03 |
16:32 |
|
210 |
47.4 |
14-Mar-03 |
15:55 |
16-Mar-03 |
15:49 |
|
210 |
49.3 |
14-Mar-03 |
15:56 |
16-Mar-03 |
15:50 |
|
211 |
0.5 |
21-Feb-03 |
16:47 |
23-Feb-03 |
16:54 |
|
212 |
1.6 |
21-Feb-03 |
16:48 |
23-Feb-03 |
16:55 |
|
213 |
1.3 |
21-Feb-03 |
16:50 |
23-Feb-03 |
16:57 |
|
301 |
1.2 |
28-Mar-03 |
17:30 |
30-Mar-03 |
17:08 |
|
302 |
0.3 |
28-Mar-03 |
17:29 |
30-Mar-03 |
17:07 |
|
303 |
0.3 |
28-Mar-03 |
17:28 |
30-Mar-03 |
17:06 |
|
304 |
1.3 |
28-Mar-03 |
17:27 |
30-Mar-03 |
17:05 |
|
305 |
1.9 |
21-Feb-03 |
16:22 |
23-Feb-03 |
16:37 |
|
305 |
2.2 |
28-Mar-03 |
17:32 |
30-Mar-03 |
17:09 |
|
306 |
1.1 |
21-Feb-03 |
16:24 |
23-Feb-03 |
16:38 |
|
307 |
1.1 |
21-Feb-03 |
16:26 |
23-Feb-03 |
16:39 |
|
307 |
1.2 |
21-Feb-03 |
16:26 |
23-Feb-03 |
16:39 |
|
308 |
0.8 |
21-Feb-03 |
16:28 |
23-Feb-03 |
16:42 |
|
309 |
1.8 |
21-Feb-03 |
16:30 |
23-Feb-03 |
16:44 |
|
310 |
1.0 |
15-Feb-03 |
9:26 |
17-Feb-03 |
9:11 |
|
311 |
1.0 |
15-Feb-03 |
9:28 |
17-Feb-03 |
9:13 |
|
312 |
2.2 |
15-Feb-03 |
9:31 |
17-Feb-03 |
9:15 |
|
313 |
2.2 |
21-Feb-03 |
16:34 |
23-Feb-03 |
16:47 |
|
314 |
5.4 |
15-Feb-03 |
9:33 |
17-Feb-03 |
9:17 |
|
314 |
5.2 |
21-Feb-03 |
16:35 |
23-Feb-03 |
16:49 |
|
314 |
5.5 |
28-Mar-03 |
17:34 |
30-Mar-03 |
17:11 |
|
315 |
1.2 |
15-Feb-03 |
9:52 |
17-Feb-03 |
9:18 |
|
316 |
0.7 |
15-Feb-03 |
9:56 |
17-Feb-03 |
9:36 |
|
317 |
1.2 |
15-Feb-03 |
9:57 |
17-Feb-03 |
9:37 |
|
318 |
1.9 |
15-Feb-03 |
9:58 |
17-Feb-03 |
9:39 |
|
401 |
1.6 |
15-Feb-03 |
9:35 |
17-Feb-03 |
9:20 |
|
402 |
0.9 |
15-Feb-03 |
9:37 |
17-Feb-03 |
9:21 |
|
403 |
3.3 |
15-Feb-03 |
9:39 |
17-Feb-03 |
9:23 |
|
404 |
0.6 |
28-Mar-03 |
17:41 |
30-Mar-03 |
17:18 |
|
405 |
0.2 |
28-Mar-03 |
17:36 |
30-Mar-03 |
17:14 |
|
406 |
1.2 |
28-Mar-03 |
17:37 |
30-Mar-03 |
17:15 |
|
407 |
1.0 |
28-Mar-03 |
17:38 |
30-Mar-03 |
17:17 |
|
408 |
1.7 |
15-Feb-03 |
9:48 |
17-Feb-03 |
9:32 |
|
408 |
1.3 |
15-Feb-03 |
9:48 |
17-Feb-03 |
9:32 |
|
409 |
1.9 |
15-Feb-03 |
9:45 |
17-Feb-03 |
9:30 |
|
410 |
0.6 |
15-Feb-03 |
9:44 |
17-Feb-03 |
9:28 |
|
411 |
1.1 |
15-Feb-03 |
9:42 |
17-Feb-03 |
9:26 |
|
411 |
0.7 |
15-Feb-03 |
9:42 |
17-Feb-03 |
9:26 |
|
412 |
0.9 |
28-Mar-03 |
17:44 |
30-Mar-03 |
17:20 |
|
413 |
1.5 |
28-Mar-03 |
17:46 |
30-Mar-03 |
17:23 |
|
414 |
2.0 |
28-Mar-03 |
17:47 |
30-Mar-03 |
17:24 |
|
414 |
1.8 |
28-Mar-03 |
17:47 |
30-Mar-03 |
17:24 |
|
415 |
1.7 |
28-Mar-03 |
17:49 |
30-Mar-03 |
17:26 |
Table 4. Results of indoor radon measurements in classrooms of 200 Science Wing after remediation.
|
Room |
Radon |
Start |
Stop |
||
|
Number |
(pCi/L) |
Date |
Time |
Date |
Time |
|
Blank |
0.3 |
25-Apr-03 |
17:00 |
27-Apr-03 |
17:00 |
|
203 |
0.3 |
25-Apr-03 |
15:57 |
27-Apr-03 |
15:31 |
|
203 |
0.2 |
25-Apr-03 |
15:57 |
27-Apr-03 |
15:31 |
|
204 |
0.2 |
25-Apr-03 |
15:55 |
27-Apr-03 |
15:30 |
|
204 |
0.3 |
25-Apr-03 |
15:55 |
27-Apr-03 |
15:30 |
|
205 |
0.3 |
25-Apr-03 |
15:53 |
27-Apr-03 |
15:29 |
|
205 |
0.2 |
25-Apr-03 |
15:53 |
27-Apr-03 |
15:29 |
|
205 |
0.2 |
25-Apr-03 |
15:53 |
27-Apr-03 |
15:29 |
|
206 |
0.2 |
25-Apr-03 |
15:49 |
27-Apr-03 |
15:26 |
|
206 |
0.6 |
25-Apr-03 |
15:49 |
27-Apr-03 |
15:26 |
|
206 |
0.5 |
25-Apr-03 |
15:49 |
27-Apr-03 |
15:26 |
|
207 |
0.3 |
25-Apr-03 |
15:46 |
27-Apr-03 |
15:24 |
|
207 |
0.2 |
25-Apr-03 |
15:46 |
27-Apr-03 |
15:24 |
|
207 |
0.2 |
25-Apr-03 |
15:46 |
27-Apr-03 |
15:24 |
|
208 |
0.3 |
25-Apr-03 |
15:44 |
27-Apr-03 |
15:22 |
|
208 |
0.4 |
25-Apr-03 |
15:44 |
27-Apr-03 |
15:22 |
|
208 |
0.2 |
25-Apr-03 |
15:44 |
27-Apr-03 |
15:22 |
|
209 |
0.2 |
25-Apr-03 |
15:40 |
27-Apr-03 |
15:19 |
|
209 |
0.3 |
25-Apr-03 |
15:40 |
27-Apr-03 |
15:19 |
|
209 |
0.2 |
25-Apr-03 |
15:40 |
27-Apr-03 |
15:19 |
|
210 |
0.4 |
25-Apr-03 |
15:37 |
27-Apr-03 |
15:18 |
|
210 |
0.2 |
25-Apr-03 |
15:37 |
27-Apr-03 |
15:18 |
|
210 |
0.4 |
25-Apr-03 |
15:37 |
27-Apr-03 |
15:18 |
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