Multnomah Education Service District

Transcription

1 Cascade Radon, Inc NE Airport Way Bldg.9 Testing, Mitigation, Portland, Oregon Systems Design Phone: (503) CCB / CASCARI927C1 Fax: (503) Office@CascadeRadon.com Radon Survey Analysis Job# 16-C073S.R2 for Multnomah Education Service District properties located at Helensview School 8678 NE Sumner St Portland OR & Wheatley School NE Sacramento St Portland OR c/o Rich Wehring / Facilities Supervisor January 4, 2017 Cascade Radon Inc. is a Woman-Owned Small Business (WOSB)

2 Table of Contents INTRODUCTION... 3 BACKGROUND... 3 BUILDING CONSTRUCTION... 4 METHODS... 4 SITE EVALUATION... 4 RADON LEVEL MEASUREMENTS... 5 Radon Level Diagnostics... 5 MITIGATION DIAGNOSTICS... 6 Individual Classroom Sub-Soil Depressurization... 7 RESULTS... 8 SITE EVALUATION... 8 RADON LEVEL MEASUREMENTS Radon Level Diagnostics MITIGATION DIAGNOSTICS Individual Classroom Sub-Soil Depressurization DISCUSSION/RECOMMENDATIONS REFERENCES APPENDIX WHEATLEY SCHOOL INITIAL TEST DATA APPENDIX HELENSVIEW SCHOOL INITIAL TEST DATA Page 2 of 34

3 Introduction The following report documents a diagnostic evaluation of the radon levels for Multnomah Education Service District. Cascade Radon, Inc. was contracted to perform a radon investigation, diagnostic testing, and assist in developing a mitigation strategy for Helensview School and Wheatley School. The basic scope of the study involved review of prior radon testing data, mapping of test data as needed, investigation of the building plans, structure, and HVAC related to the areas being addressed, and diagnostic work which included temporary sub-slab depressurization and on-site investigation. This evaluation was conducted between the dates of August 2, 2016 and November 21, Background Initial radon testing for both Helensview School and Wheatley School was performed from July 15, 2016 to July 18, 2016 using liquid scintillation. Indy Safety performed initial testing (Appendix 1, Appendix 2). Based on information provided by the Client to Cascade Radon, the HVAC system was shut down during the initial testing at both locations. However, during periods of occupation at both schools, the HVAC system is normally running. Per guidelines put forth by the American Association of Radon Scientists and Technologists (AARST) and the American National Standards Institute (ANSI), large buildings and schools should have testing performed with the HVAC set such that it resembles periods of highest occupancy (AARST Consortium on National Radon Standards, 2014). Testing under these conditions, the test values will be more comparable to what occupants of the building will experience daily. It is recommended by the Oregon Health Authority (OHA) that the protocols set forth by AARST for large buildings be used when testing for radon in schools to accurately test per Oregon Revised Statute (ORS) (Oregon Health Authority, 2016). According to the National Radon Standards (AARST Consortium on National Radon Standards, 2014), and the OHA (Oregon Health Authority, 2016), when short-term testing levels are found to be between 2 and 4 it is recommended that re-testing be performed at least every 5 years and whenever significant changes to the building s Page 3 of 34

4 structure or mechanical system occurs. When levels are greater than or equal to 4, but less than 8, a follow-up short-term or long-term test is recommended, however long-term testing is not recommended if the building employs 8-12 hour occupancy HVAC setbacks. Should the results be great than or equal to 8, short-term follow-up testing should be conducted and the initial and the follow-up short-term testing values averaged to determine if remedial action should be taken. All testing should initially be performed under occupied operating conditions. Building Construction Building construction for both Helensview School and Wheatley School is similar, though not identical due to differences in geomorphology of the building site. Both school buildings are single story, with slab on grade construction for both the classrooms and offices of the building. Each school also has interconnected utility tunnels that run under the main hallways. At Helensview, the tunnels do not extend beyond the entry area of the school. For Wheatley School, the west wing of the building does not have a central hallway; instead the tunnel runs down the central median of the classrooms, which are interconnected. The heating and cooling system (HVAC) within both schools operate similarly. In both cases, a large squirrel cage blower functions to distribute supply air for the building through the utility tunnels. Within the tunnels there are branch lines which service individual occupied areas. Cooling for the rooms is provided in several areas at both schools by window mounted air-conditioner units. The main fan runs most of the time as there is no timer set for the system at either location. However, the fan system at Helensview does have an auto function, while the system at Wheatley has only the option for on or off using a master control switch at the bottom of the fan room. Methods Site Evaluation The first phase of diagnostic evaluation is to perform a walkthrough of both facilities and the utility tunnels, and map the radon levels in the individual classrooms from prior test Page 4 of 34

5 data. With this process, we can examine the building construction and develop a testing strategy for each of the facilities. For the radon level diagnostics, one room in each wing of each building is selected. The room selection is based on average value from the initial testing and its location within the wing. In most cases, the selected room is the classroom in each wing with the highest average radon value from initial testing. The rooms chosen at each school for testing are as follows: Helensview School Classroom #4 Gym Classroom #18 Wheatley School Classroom #4 Library Classroom #17 Radon Level Measurements Radon measurements within the buildings are performed using two measurement techniques. A. RadStar RS800 continuous radon monitor (CRM): These monitors integrate, record, and produce hourly readings in increments of 1 hour. The monitors are placed in a location for a minimum 48-hour period. B. Activated Charcoal (AC) test kits from Air Chek: These devices are equilibrating devices. These devices are deployed for a period of 48 hours to a maximum of 7 days. The device is sent to a lab for evaluation that then provides an average for the measurement period. Radon Level Diagnostics The first phase in the evaluation process is to perform baseline testing, using the rooms selected in the site evaluation. The classrooms are tested under occupied building conditions using CRM devices. This involves ensuring that the HVAC system is operating as it would when the school is occupied; this is to ensure that the levels being measured are consistent with those that are generally experienced by students and staff. After baseline testing is performed and the data compared to the initial testing data, a follow-up round of testing is performed in the same locations with the HVAC system turned off. This is done to examine the impact of the HVAC system on the radon levels within the rooms. Page 5 of 34

6 The second phase of the radon level diagnostics is to evaluate the difference in the radon concentrations for the rooms and the utility tunnels. This process assists in determining the radon levels in the utility tunnels and how they contribute to the radon levels within the rooms. The process also assists in evaluating what the time delay is for radon level changes, by initiating testing with the HVAC system off followed immediate testing with the HVAC system initiated. For this specific evaluation, the room in each building with the highest radon level from the initial radon testing, and the area of the utility tunnels servicing these specific rooms were tested using CRM devices. Helensview: Room 18 Wheatley: Room 4 Testing is initiated with the HVAC system off, after the minimum 48 hours of testing, the data is collected from the devices and the devices are reset. The HVAC system is turned on and the testing is performed for another 48 hours. For the third phase of testing, a monitor is placed in the utility tunnels near a supply air return, and a second monitor is placed in the room to which the supply air return is connected to attempt to eliminate possible variations that could occur in room concentrations due to proximity of the room monitor and the tunnel monitor. In both buildings, the tunnel tested services the area of the building with the highest radon levels from initial testing. The monitor is placed as far back into the tunnel as is reasonably possible to reach without possible damage to pipes within the tunnels and near a supply air duct. The room to which the supply air was connected is determined by length traveled into the tunnel and the associated length at the surface. The rooms tested were as follows: Helensview: Room 12 Wheatley: Room 17 The results of the radon level diagnostics are used to determine the mitigation design should the need arise for the buildings. Mitigation Diagnostics The two sites are of similar construction and design, this allows for one site to be able to act as a proxy for the other. Therefore, mitigation diagnostics were performed in only one Page 6 of 34

7 room at one site to reduce the cost of determining an effective mitigation strategy for the schools should one be needed. For the purposes of diagnostic testing, a temporary sub-soil depressurization system is put into place and radon level monitoring is performed for a minimum of 48 hours to examine the effect of the mitigation on the radon levels within the room. The mitigation system can also assist in the determination of whether the floor slab or the utility tunnels are the primary cause of the elevated radon levels within the rooms of the building. Individual Classroom Sub-Soil Depressurization The site with the room experiencing the highest radon levels during the initial testing phase is selected for mitigation diagnostics. To perform mitigation diagnostics, a temporary mitigation system is installed in the room. This temporary system is placed such that it acts as a permanent mitigation system, only it can be more easily altered or removed to evaluate the most effective system design for the building. While installation of the temporary system is performed, the HVAC system is shut down immediately prior to installation commencing. Once the temporary mitigation system is in place, regular testing of the radon levels with the HVAC system turned off is performed using a CRM device for a minimum of 48 hours. This allows for the determination of whether the mitigation system is sufficient to bring the levels in the room tested to below the EPA recommended mitigation level of 4.0. The tunnel and three other locations in different regions of the building are also tested to determine if a mitigation system will have impacts to these areas. How well the system functions to reduce radon levels is the next examination of the radon system. The HVAC system is turned off 24 hours prior to the temporary mitigation system being initiated to allow for elevation of the radon levels within the building. This process creates a worst-case scenario to determine the mitigation system effectiveness. Once the mitigation system is initiated, the following day, testing is started to examine how long it takes for the system to reduce radon levels in the subject room using a CRM device in the room being mitigated directly. Page 7 of 34

8 The final evaluation of the system function is to perform communication testing for the mitigation system as well as isolation of the rooms from the tunnel. The communication test assists in determining the approximate number of rooms that a single sub-soil system can mitigate. Isolation of the rooms from the tunnel HVAC supply air allows for determining if a mitigation strategy needs to include tunnel depressurization in conjunction with the classroom sub-soil depressurization. To do this, the temporary system is turned on and the HVAC system is turned off. The HVAC supply vents are sealed in the room where the temporary mitigation system is running and the two adjacent rooms. The three classrooms are then tested using CRM devices for a period of no less than 48 hours. Four of the remaining rooms in the same wing, and the tunnel, are tested using AC test kits. Results Site Evaluation Initial testing of the building results indicated that several of the rooms in the two schools had radon levels elevated above 8. These locations are as follows: Classroom #1 Classroom #3 Classroom #4 Classroom #6 Classroom #8 Helensview NW Hall Activity Room Stage Gym South Ramp Classroom #9 Classroom #15 Classroom #16 Classroom #17 Classroom #18 Classroom #1 Classroom #2 Safe Room #1 Safe Room #2 Classroom #11 Classroom #12 Wheatley Classroom #13 Classroom #14 Classroom #15 Classroom #16 Classroom #17 Classroom #18 Gym Kitchen Health Room Copy Room Main Office Library The initial radon levels for each of the schools were mapped to determine if there was a pattern in the radon level elevations. Looking at the mapped values for the initial radon values at Helensview, the highest radon levels were found in Room #18 with a value of 62.4 Page 8 of 34

9 . The data indicates a trend of higher values at the southwestern wing of the school, Figure 1. Data mapping for Wheatley School was also performed using the initial test data. The mapping indicates that the highest radon value is in the library, while the highest classroom is room 17 in the southwest hallway. Overall, the trend indicates that the highest radon levels are in the eastern end of the building, Figure 2. Figure 1. Helensview School mapped initial radon values. Mapping of the values indicates that the highest radon value is found in Room #18 in the southwest hallway. The map indicates a trend of higher values on the southwestern portion of the school. Page 9 of 34

10 Figure 2. From the map, the highest radon values are in the library. The highest level for classrooms is found in room 17. Based on the data mapping, the radon levels are higher in the eastern portion of the building. Once the radon levels were mapped, an on-site evaluation was performed for each building. From the on-site evaluation, the utility tunnels were mapped and found to service as the main supply air for both buildings, Figure 3 and Figure 4. At Helensview, the main office area is the only area of the building that does not receive supply air from the utility tunnels. At this location, it was also found that the section of the utility tunnel that services the west wing of the building has a lift/elevation difference of approximately 5 feet. At Wheatley, the utility tunnels service all areas of the building and are at approximately the same level. Page 10 of 34

11 Figure 3. Mapping of the utility tunnels for Helensview School. Tunnels act as supply air for the building except for the office area at the east end of the building. The southwest wing of the utility tunnels are at a higher elevation than those for the rest of the school. Figure 4. Mapping of the utility tunnels for Wheatley School. All the tunnels are at approximately the same elevation and there are no areas that are not served by the utility tunnels for supply air. Page 11 of 34

12 Radon Level Measurements Radon Level Diagnostics At both locations, the first phase of radon testing, with the HVAC system running continuously, found that the radon levels during the testing period were significantly lower than what was found during the initial testing phase. In both buildings, all the rooms tested were below the EPA recommended action level of 4.0, Table 1 and Table 2. Followup testing that allowed for a comparison between the initial test conditions was performed and found that radon levels at Helensview were similarly elevated, however, at Wheatley the elevated radon levels were not replicated in any of the classrooms. Table 1. Data table of short-term radon testing at Helensview School. Initially the testing was performed with the system turned on. Follow-up testing was performed with the system off to determine if the operation mode of the HVAC affects the radon values in the building. Room Tested Monitor ID Average Maximum Minimum HVAC Gym /12 12:00 8/15 12: ON Room /12 12:00 8/15 12: ON Room /12 12:00 8/15 12: ON Gym /15 12:00 8/17 13: OFF Room /15 12:00 8/17 13: OFF Room /15 12:00 8/17 13: OFF Table 2. Data table of short-term radon testing for Wheatley School. The first round of testing was performed with the HVAC system turned on. Testing was performed afterward to validate the elevated levels from the initial testing. The follow-up levels did not reach the elevated levels that were observed in the initial test data set. Room Tested Monitor ID Average Maximum Minimum HVAC Room /12 12:30 8/15 12: ON Room /12 12:30 8/15 12: ON Library /12 12:30 8/15 12: ON Room /15 12:30 8/17 14: OFF Room /15 12:30 8/17 14: OFF Library /15 12:30 8/17 14: OFF At the two schools, a room with some of the highest radon levels, with a direct connection to the utility tunnels, was selected for further investigation. At Helensview, Room 18 was selected due to the higher radon levels found during both the initial testing and during follow-up testing under the same testing conditions, Table 3. For Wheatley, Room 4 was selected as it had the highest radon levels during the testing diagnostics. In this testing, the radon levels in the tunnel were also evaluated for contribution to the levels in the Page 12 of 34

13 classrooms. The results of the testing compared both the levels with the HVAC off and the HVAC on. At Helensview, the tunnels do not appear to be a dominant contributor to the radon levels within the rooms, with the levels in the classroom nearly 4 times the level of what was found in the classroom at the time of the testing, Table 4. Table 3. Testing of the classroom and tunnels at Helensview. Testing with the system off reveals that the radon levels in the classroom tend to be nearly 4 times higher than what they are in the tunnel. Room Tested Monitor ID Average Maximum Minimum HVAC Room /17 13:00 8/19 13: OFF West Wing Tunnel /17 13:00 8/19 13: OFF Room /19 13:00 8/23 13: ON West Wing Tunnel /19 13:00 8/23 13: ON Table 4. Testing of the classroom and tunnels at Wheatley. Testing with the HVAC system off indicates that the radon levels tended to be approximately 5 times higher than those recorded in the classroom serviced by the same region of the steam tunnels during the same time. Room Tested Monitor ID Average Maximum Minimum HVAC Central Tunnel /17 12:00 8/19 13: OFF Room /17 12:00 8/19 13: OFF Central Tunnel /19 13:00 8/23 14: ON Room /19 13:00 8/23 14: ON To determine what the estimated length of time would be necessary to properly flush the radon from the classrooms, the radon monitors were placed as close to the end of the tunnels as could be reached, and as far from the fan room as possible. In the tunnels at Helensview, the pipes in the west hallway utility tunnel makes passage beyond Room 12 difficult, therefore the utility tunnel in this area was tested, as well as Room 12. Examination of the hourly data, after allowing the monitor to sit in the location for 48 hours prior with the HVAC system off, indicate that it can take a minimum of 6 hours to bring the levels consistently below the EPA recommended level of 4.0 within the classrooms. It was also found that at this location, the radon level in the tunnels was higher than the level that was recorded in the classroom, Table 5. Page 13 of 34

14 Table 5. Levels at Helensview for Room 12 and the tunnel supply air region. In this region of the building the average radon value was higher that what was found in the classroom. Room Tested Monitor ID Average Maximum Minimum HVAC Room /9 12:30 9/12 7: OFF Room 12 Tunnel Supply Air /9 12:30 9/12 7: OFF Room /12 7:00 9/14 14: ON Room 12 Tunnel Supply Air /12 7:00 9/14 14: ON Using the same criteria for Wheatley, the monitor was placed at the furthest supply air access in the southeast hallway. The supply air passage at this location services room 17. The radon levels were consistent to what was found when previously testing in the tunnels, with the tunnels having a higher radon level than the classroom that it services. In this location is again took a minimum of 6 hours for the radon levels to drop to a consistent level once the HVAC system was initiated, Table 6. Table 6. Levels at Wheatley for Room 17 and the associated supply air region. In this region the building, the average radon value in the tunnels was higher than what was found in the classroom, which is consistent with what was found in prior testing. Room Tested Monitor ID Average Maximum Minimum HVAC Room /9 13:30 9/12 7: OFF Room 17- Tunnel Supply Air /9 13:30 9/12 7: OFF Room /12 7:30 9/14 14: ON Room 17 Tunnel Supply Air /12 7:30 9/14 14: ON The results of the radon level diagnostic testing provide information regarding the most likely pathways for the radon into the building. This data assists in the determination of an effective mitigation strategy for the building. Mitigation Diagnostics Individual Classroom Sub-Soil Depressurization The process of sub-soil depressurization of the slab in room 18 at Helensview School resulted in decreased radon levels within the classroom being mitigated, Table 7. However, Page 14 of 34

15 depressurization of the classroom slab alone was insufficient to decrease the levels in the room below the threshold of 4.0 consistently during the testing period. It was also noted that the radon levels in other areas of the building did not appear to be impacted by the depressurization system in Room 18. Table 7. Radon testing results after 61 hours of radon testing during temporary sub-slab depressurization of room 18 at Helensview School. Room Tested Monitor ID Average Maximum Minimum HVAC Room /7 18:00 10/10 7: OFF West Tunnel /7 18:00 10/10 7: OFF Activity Room /7 18:00 10/10 7: OFF Gym /7 18:00 10/10 7: OFF Room /7 18:00 10/10 7: OFF In the second stage of diagnostic testing, the continuously running HVAC system was shut off approximately 24 hours prior to the temporary system being initiated. This process indicated that the levels within the building begin to increase substantially after only two hours. The average radon levels were 21.1 prior to the initiation of the temporary sub-slab depressurization system. Once the temporary system was initiated, the levels began to decrease in the room immediately with an overall average of 3.8 from the start of the temporary mitigation system. Table 8. Radon testing results from 64 hours of radon testing following shut-down of continuous HVAC operation 10 hours prior to temporary mitigation system initiation. Room Tested Monitor ID Average Maximum Minimum HVAC Room /14 14:30 10/17 7: OFF The third stage of diagnostic testing of the mitigation system was to determine the communication between the rooms, and to isolate classrooms 16, 17, and 18 from the HVAC supply air. Based on the received data from the communication testing, a single system will mitigate approximately three rooms laying on a common side of a ventilation tunnel. Isolation of the classrooms from the HVAC supply tunnels did create a drastic reduction in the radon levels in the classroom with the mitigation system running, Table 9. Page 15 of 34

16 It is notable that the levels in the tunnel were higher than what was recorded in all of the classrooms during the testing period. Table 9. Evaluation of the mitigation system communication from a single suction point at Helensview School. The communication extends for approximately three rooms. Room Tested Monitor ID Average Maximum Minimum HVAC Room /18 14:00 11/21 8: OFF Room /18 14:00 11/21 8: OFF Room /18 14:00 11/21 8: OFF Room /18 14:00 11/21 8: ± OFF Room /18 14:00 11/21 8: ± OFF Room /18 14:00 11/21 8: ± OFF Room /18 14:00 11/21 8: ± OFF Tunnel /18 14:00 11/21 8: ± OFF Discussion/Recommendations The concentration of radon gas in indoor air can vary widely. It may fluctuate from day to day, week to week, and season to season. Indoor radon levels may be affected by barometric pressure, strong winds, rain-soaked ground, snow cover, heating and A/C systems, building construction, open windows, and the like. Evaluation of both Helensview and Wheatley Schools indicate that the operation of the HVAC system has a drastically impact the radon concentrations within occupied areas of both schools. When the system is set to occupied conditions, the radon levels in both schools during the testing period dropped well below the EPA recommended mitigation level of 4.0. Current testing indicates that if the HVAC system is operating at least 6-8 hours prior to occupancy, the radon levels will tend to be below the EPA recommended level by the time occupancy occurs. However, when the HVAC system is shut down, the radon levels within the buildings can reach levels above 4.0 in as little as 2 hours. Page 16 of 34

17 It is recommended that testing per AARST standards (AARST Consortium on National Radon Standards, 2014) for large buildings and schools be performed to verify that the radon levels for verification of these results. It is also recommended that interval testing as outlined by both OHA and AARST (Oregon Health Authority, 2016) be followed to ensure that the radon levels remain low over time. Follow-up testing of a building should also be performed if there are any significant changes to the building structure or mechanical systems. Should periodic use of the HVAC system be put into place, it is highly recommended that mitigation action involving active sub-soil depressurization be performed to ensure that the levels will be low during periods of occupancy. A properly installed mitigation system should target both the slab of the classrooms and the utility tunnels. Page 17 of 34

18 References AARST Consortium on National Radon Standards. (2014). Protocol for Conducting Measurements of Radon and Radon Decay Products in Schools and Large Buildings. Fletcher: AARST. Oregon Health Authority. (2016). Testing for Elevated Radon in Oregon Schools. Public Health Division. Portland: Oregon Health Authority. Page 18 of 34

19 Appendix 1 Wheatley School Initial Test Data Page 19 of 34

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27 Appendix 2 Helensview School Initial Test Data Page 27 of 34

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