Background Information

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1 March 11, 2014 DRAFT Colin Morrison Boulder Valley School District 6500 Arapahoe, P.O. Box 9011 Boulder, CO Re: Casey Middle School at 1301 High Street in Boulder, Colorado Indoor Air Quality Monitoring (Hydrogen Sulfide) Dear Mr. Morrison: At your request, on March 7, 2014, Tony Konowal of Quality Environmental Services & Technologies, Inc. (QUEST) met with you and school principal Alison Boggs and conducted the first of two (2) three-day hydrogen sulfide (H 2 S) monitoring assessments in three areas of concern inside Casey Middle School located at 1301 High Street in Boulder, Colorado. The purpose of QUEST s assessment was to conduct hydrogen sulfide monitoring following building occupant reports of ongoing, intermittent sewer gas smells inside the school. This report summarizes our site observations, hydrogen sulfide and trace gas monitoring levels, and conclusions. Background Information Site Background Information As you reported by telephone and while on site, an intermittent sewer gas odor has been noticed by Casey Middle School occupants for approximately three years, starting in December 2010, shortly after the school first opened in August As noted in a memo generated on May 30, 2013 by Boulder Valley School District s (BVSD) Director of Maintenance, Mike Cuskelly, the source of the odor at that time was determined to be at the floor drains in the science classrooms, restrooms, kitchen, and mechanical rooms. New automatic primers for the p-traps in the floor drains were installed to remedy the problem. In the fall of 2012, the odors were again noticed. In the early winter of 2012, Studer vents were placed on approximately half of the school s sewer vent pipes; after adjustments were made to the Studor vents, the odor problem was temporarily resolved. The odors returned January through March After this latest reoccurrence, the odors were reduced by creating a condition of positive airflow in the building. While on site, Ms. Boggs noted that at present, the HVAC system is shut down during the weekend, except during the hours of 10:00 a.m and noon on Sundays. Ms. Boggs reported that the odors are most noticeable on Monday mornings. Routine HVAC maintenance has created no change in the odors. Odors reportedly are worse in the first floor (lower level) hallway and generally lessen as you go up. You stated that BVSD had performed hydrogen sulfide monitoring at Casey Middle School in 2011 and 2012, and that no detectable concentrations (in parts per million [ppm]) of hydrogen sulfide were ever identified. During days when the odor is strongest, however, there is

2 Mr. Colin Morrison March 11, 2014 Page 2 DRAFT current concern that there may be low levels of hydrogen sulfide present in the indoor air. You retained QUEST to monitor the indoor air for hydrogen sulfide in selected locations where the odor has been intermittently present. Sewer Gas Background Information Sewer gas is a generic name for a complex mixture of toxic and non-toxic gases that can be present at varying levels depending upon the source. Sewer gas is formed from the natural process of decomposition of organic materials in sewage. Since the decomposition of organic material takes time, drain lines close to the source typically do not contain high concentrations of toxic gasses. Gases produced by wastewater decomposition can include hydrogen sulfide (H 2 S), ammonia (NH 3 ), methane (CH 4 ), and carbon dioxide (CO 2 ). Hydrogen sulfide and ammonia are the only malodorous gases in sewer gas. The U.S. Occupational Safety & Health Administration (OSHA) notes that hydrogen sulfide has a pungent rotten egg odor at low concentrations and is extremely flammable and highly toxic. 1 The Centers for Disease Control and Prevention (CDC) note that one s sense of smell should not be relied upon to warn of the continuous presence of hydrogen sulfide because it becomes rapidly fatigued. 2 Hydrogen sulfide is heavier than air and thus may travel along the ground or low-lying areas. 3 Sewer gas also includes sulfur dioxide (SO 2 ), nitrous oxides (NO x ), biological organisms, water vapor, and chemicals introduced into wastewater such as chlorine bleaches, industrial solvents, and gasoline. The presence, concentrations and emissions of these components can vary with time, composition of the sewage, temperature, and ph. 1 OSHA, Safety and Health Topics, Hydrogen Sulfide. Accessed at 2 CDC, NIOSH Pocket Guide to Chemical Hazards, Hydrogen sulfide. Accessed at npgd0337.html. 3 OSHA Fact Sheet, Hydrogen Sulfide (H 2 S), Oct Gas Detection & Monitoring Results March 7-10, 2014 On March 7, 2014, the QUEST representative met with you and conducted initial trace gas monitoring in three locations (selected by Ms. Boggs) at Casey Middle School: Room C140 on the lower level, Room C201 (Copy Room) on the main level, and Room B360 on the upper level. The QUEST representative utilized an Extech relative humidity and temperature pen to measure relative humidity and temperature in the three indoor locations, as well as outside of the school. At the time of our inspection, the outdoor relative humidity was 38.6% at 40.1 degrees Fahrenheit. The indoor relative humidity was 23.9 at 78.6 degrees Fahrenheit in Room C140, 27.5% at 78.0 degrees Fahrenheit in Room C201, and 30.6% at 76.8 degrees Fahrenheit in Room B360. These values are representative of normal, dry air. QUEST also utilized a BW Technologies GasAlertMicro multi-gas trace gas detector and an AZ Instrument AZ7755 carbon dioxide monitor to measure airborne concentrations of carbon monoxide (ppm), carbon dioxide (ppm), combustible gases (% LEL), hydrogen sulfide (ppm), and oxygen (%) in the accessible areas of the school. The detected carbon dioxide levels were 390 ppm outdoors and ranged from

3 Mr. Colin Morrison March 11, 2014 Page 3 DRAFT 580 to 787 ppm inside of the school. All indoor locations contained 20.9% oxygen. No hydrogen sulfide, combustible gasses LEL, or carbon monoxide levels were detected in the school. These concentrations are considered to be well within normal and expected ranges, with no anomalies detected. From the afternoon of Friday, March 7 to the morning of Monday, March 10, 2014, the QUEST representative conducted the initial hydrogen sulfide detection assessment. QUEST placed three (3) Jerome 631-X hydrogen sulfide analyzers in C140, C201, and B360 to run continuously and record hydrogen sulfide levels every ten (10) minutes for approximately 70 hours. At the time of hydrogen sulfide detection monitor placement, the QUEST representative did not detect a sewer gas or any other odor inside or outside the school in the areas of concern. As noted above, the HVAC system is shut down over the weekend, except for 10:00 a.m to noon on Sundays, and the intermittent odors are most noticeable on Monday mornings. During the monitoring period, 418 readings were collected in Room C140, and 417 readings each were collected in Rooms C201 and B360. On March 10, 2014, the QUEST representative retrieved the three hydrogen sulfide monitors from the school and then downloaded and analyzed the data at the QUEST office. Analysis of the data recorded with the Jerome 631-X hydrogen sulfide analyzers is detailed in the following table and the attached data reports/graphs (of note, a graph could not be generated for B360). Results have been converted from parts per million (ppm), as recorded in the data reports, to parts per billion (ppb). For purposes of comparison with the detected hydrogen sulfide concentrations, the Occupational Safety and Health Administration (OSHA) permissible exposure level (PEL), American Conference of Government Industrial Hygienists (ACGIH) threshold limit value (TLV), and the National Institute of Occupational Safety and Health (NIOSH) recommended exposure level (REL) were identified and converted to ppb. The following table compares the detected hydrogen sulfide concentrations in each location to the lowest of the available OSHA, ACGIH, or NIOSH values as well as to published odor and nuisance thresholds. Room Max. H2S Reading Avg. H2S Reading H2S Odor Threshold H2S Nuisance Threshold Lowest of the available OSHA PEL, ACGIH TLV, NIOSH REL C140 4 ppb 0 ppb 8 ppb 40 ppb 1,000 ppb C201 6 ppb 1 ppb 8 ppb 40 ppb 1,000 ppb B360 6 ppb 1 ppb 8 ppb 40 ppb 1,000 ppb Maximum and average readings in all three locations were well below the lowest published hydrogen sulfide exposure limit (ACGIH TLV). Maximum and average readings in all three locations were also below the published hydrogen sulfide odor and nuisance thresholds. Generally, the highest concentrations of hydrogen sulfide were identified between 7:00 a.m. and noon (in all three locations) on Monday, March 10, (Please note that times from the March 10, 2014 data logs have been adjusted for Daylight Savings Time.) Of note, the hydrogen sulfide analyzers were removed from the school at approximately noon on March 10, 2014 for data retrieval purposes. In summary, the hydrogen sulfide concentrations identified in the three locations sampled at Casey Middle School during the March 7-10, 2014 monitoring period do not indicate any odor or safety concerns for building occupants.

4 Mr. Colin Morrison March 11, 2014 Page 4 DRAFT March 11-14, 2014 QUEST will conduct a second hydrogen sulfide detection assessment in the same manner from March 11 to March 14, Following analysis of the data recorded with the Jerome 631-X hydrogen sulfide analyzers during the second monitoring period, this report will be finalized. Conclusions Based on QUEST s initial hydrogen sulfide detection and trace gas monitoring assessment, conducted from March 7 to March 10, 2014, in three areas of concern inside Casey Middle School, we provide the following conclusions: 1. Intermittent sewer gas odors have been noticed in Casey Middle School for approximately three years, starting in December 2010; 2. During trace gas monitoring on March 7, 2014 (in Rooms C140, C201, and B360), the humidity levels and temperatures as well as the detected concentrations of carbon dioxide and oxygen were well within normal and expected values. No carbon monoxide, hydrogen sulfide (ppm), or combustible gasses LEL were detected; 3. Maximum and average hydrogen sulfide readings in all three locations during the March 7-10, 2014 monitoring were below the published odor and nuisance thresholds as well as below the lowest published hydrogen sulfide exposure limit (ACGIH TLV); 4. Generally, the highest concentrations of hydrogen sulfide were identified between 7:00 a.m. and noon (in all three locations) on Monday, March 10, (Please note that times from the March 10, 2014 data logs have been adjusted for Daylight Savings Time.) Although all of the identified levels on March 10, 2014 were below the odor threshold, a correlation may exist with building occupant historical reports of the odor being most noticeable on Monday mornings, as this was the time period in which QUEST observed the highest hydrogen sulfide concentrations; 5. In summary, the hydrogen sulfide concentrations identified in the three locations sampled at Casey Middle School during the March 7-10, 2014 monitoring period do not indicate any odor or safety concerns for building occupants; 6. QUEST will conduct a second hydrogen sulfide detection assessment in the same manner from March 11 to March 14, Following analysis of the data recorded with the Jerome 631-X hydrogen sulfide analyzers during the second monitoring period, this report will be finalized. The conclusions presented in this report are based on limited observations and monitoring. It is not possible to confirm the full extent of hazardous conditions and/or air quality concerns. Conclusions should not be construed as a guaranteed presence or absence of all such concerns, but merely the results of the evaluation. QUEST reserves the right to modify our findings and conclusions if

5 Mr. Colin Morrison March 11, 2014 Page 5 DRAFT additional information becomes available. If you have any questions, or if we may be of additional service, please contact Bob Woellner at QUEST. We look forward to our continued association. Sincerely, Robert A. Woellner President/Industrial Hygienist Anatole (Tony) Konowal Project Manager/Industrial Hygienist Attachments: March 7-10, 2014 Data Reports & Graphs for Rooms C140, C201, and B360

6 Site Name: BVSD; Casey Middle School Address: Sample Location: Technician: #1 (C140) Mr Brown Instrument: Jim's 631, 631-X, SN 1004 Comment: Date/Time: Mar :43pm Alarm Setpoint: 0 (ppm) DATE/TIME RESULT (ppm) Page 1 of 8 1 Mar :31:51pm Mar :42:21pm Mar :52:21pm Mar :02:21pm Mar :12:21pm Mar :22:20pm Mar :32:20pm Mar :42:20pm Mar :52:20pm Mar :02:20pm Mar :12:19pm Mar :22:19pm Mar :32:19pm Mar :42:19pm Mar :52:19pm Mar :02:19pm Mar :12:18pm Mar :22:18pm Mar :32:18pm Mar :42:18pm Mar :52:18pm Mar :02:17pm Mar :12:17pm Mar :22:17pm Mar :32:17pm Mar :42:17pm Mar :52:17pm Mar :02:16pm Mar :12:16pm Mar :22:16pm Mar :32:16pm Mar :42:16pm Mar :52:16pm Mar :02:15pm Mar :12:15pm Mar :22:15pm Mar :32:15pm Mar :42:15pm Mar :52:14pm Mar :02:14pm Mar :12:14pm Mar :22:14pm Mar :32:14pm Mar :42:14pm Mar :52:13pm Mar :02:13pm Mar :12:13pm Mar :22:13pm Mar :32:13pm.000

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14 Site Name: Address: BVSD; Casey Middle School Sample Location: #1 (C140) Technician: Mr Brown Instrument: Jim's 631, 631-X, SN 1004 Comment: Date/Time: Mar :43pm Alarm Setpoint: 0 (ppm) Result (ppm) Mar-07 12AM Mar-07 12PM Mar-08 12AM Mar-08 12PM Mar-09 12AM Mar-09 12PM Mar-10 12AM Mar-10 12PM Mar-11 12AM Day

15 Site Name: BVSD; Casey Middle School Address: Sample Location: Technician: #2 (C201) Mr Brown Instrument: Jim's 631, 631-X, SN 1004 Comment: Date/Time: Mar :54pm Alarm Setpoint: 0 (ppm) DATE/TIME RESULT (ppm) Page 1 of 8 1 Mar :48:03pm Mar :58:33pm Mar :08:33pm Mar :18:33pm Mar :28:33pm Mar :38:33pm Mar :48:32pm Mar :58:32pm Mar :08:32pm Mar :18:32pm Mar :28:32pm Mar :38:32pm Mar :48:31pm Mar :58:31pm Mar :08:31pm Mar :18:31pm Mar :28:31pm Mar :38:30pm Mar :48:30pm Mar :58:30pm Mar :08:30pm Mar :18:30pm Mar :28:30pm Mar :38:29pm Mar :48:29pm Mar :58:29pm Mar :08:29pm Mar :18:29pm Mar :28:29pm Mar :38:28pm Mar :48:28pm Mar :58:28pm Mar :08:28pm Mar :18:28pm Mar :28:27pm Mar :38:27pm Mar :48:27pm Mar :58:27pm Mar :08:27pm Mar :18:27pm Mar :28:26pm Mar :38:26pm Mar :48:26pm Mar :58:26pm Mar :08:26pm Mar :18:26pm Mar :28:25pm Mar :38:25pm Mar :48:25pm.002

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22 Page 8 of Mar :57:22am Mar :07:22am Mar :17:22am Mar :27:22am Mar :37:21am Mar :47:21am Mar :57:21am Mar :07:21am Mar :17:21am Mar :27:20am Mar :37:20am Mar :47:20am Mar :57:20am Mar :07:20am.005 Readings: 417 Minimum: 0 Maximum: Average: SD:

23 Site Name: Address: BVSD; Casey Middle School Sample Location: #2 (C201) Technician: Mr Brown Instrument: Jim's 631, 631-X, SN 1004 Comment: Date/Time: Mar :54pm Alarm Setpoint: 0 (ppm) Result (ppm) Mar-07 12AM Mar-07 12PM Mar-08 12AM Mar-08 12PM Mar-09 12AM Mar-09 12PM Mar-10 12AM Mar-10 12PM Mar-11 12AM Day

24 Site Name: BVSD; Casey Middle School Address: Sample Location: Technician: #3 (B360) Mr Brown Instrument: Jim's 631, 631-X, SN 1004 Comment: Date/Time: Mar :00pm Alarm Setpoint: 0 (ppm) DATE/TIME RESULT (ppm) Page 1 of 8 1 Mar :53:53pm??5. 2 Mar :55:52pm /III End Of Session 3 Mar :55:52pm Mar :06:22pm Mar :16:22pm Mar :26:21pm Mar :36:21pm Mar :46:21pm Mar :56:21pm Mar :06:21pm Mar :16:20pm Mar :26:20pm Mar :36:20pm Mar :46:20pm Mar :56:19pm Mar :06:19pm Mar :16:19pm Mar :26:19pm Mar :36:19pm Mar :46:18pm Mar :56:18pm Mar :06:18pm Mar :16:18pm Mar :26:18pm Mar :36:17pm Mar :46:17pm Mar :56:17pm Mar :06:17pm Mar :16:16pm Mar :26:16pm Mar :36:16pm Mar :46:16pm Mar :56:16pm Mar :06:15pm Mar :16:15pm Mar :26:15pm Mar :36:15pm Mar :46:15pm Mar :56:14pm Mar :06:14pm Mar :16:14pm Mar :26:14pm Mar :36:13pm Mar :46:13pm Mar :56:13pm Mar :06:13pm Mar :16:13pm Mar :26:12pm Mar :36:12pm.000

25 Page 2 of 8 50 Mar :46:12pm Mar :56:12pm Mar :06:12pm Mar :16:11pm Mar :26:11pm Mar :36:11pm Mar :46:11pm Mar :56:10pm Mar :06:10pm Mar :16:10pm Mar :26:10pm Mar :36:10pm Mar :46:09pm Mar :56:09pm Mar :06:09am Mar :16:09am Mar :26:09am Mar :36:08am Mar :46:08am Mar :56:08am Mar :06:08am Mar :16:07am Mar :26:07am Mar :36:07am Mar :46:07am Mar :56:07am Mar :06:06am Mar :16:06am Mar :26:06am Mar :36:06am Mar :46:06am Mar :56:05am Mar :06:05am Mar :16:05am Mar :26:05am Mar :36:04am Mar :46:04am Mar :56:04am Mar :06:04am Mar :16:04am Mar :26:03am Mar :36:03am Mar :46:03am Mar :56:03am Mar :06:02am Mar :16:02am Mar :26:02am Mar :36:02am Mar :46:02am Mar :56:01am Mar :06:01am Mar :16:01am Mar :26:01am Mar :36:01am Mar :46:00am Mar :56:00am Mar :06:00am Mar :16:00am Mar :25:59am.000

26 Page 3 of Mar :35:59am Mar :45:59am Mar :55:59am Mar :05:59am Mar :15:58am Mar :25:58am Mar :35:58am Mar :45:58am Mar :55:58am Mar :05:57am Mar :15:57am Mar :25:57am Mar :35:57am Mar :45:56am Mar :55:56am Mar :05:56am Mar :15:56am Mar :25:56am Mar :35:55am Mar :45:55am Mar :55:55am Mar :05:55am Mar :15:55am Mar :25:54am Mar :35:54am Mar :45:54am Mar :55:54am Mar :05:53pm Mar :15:53pm Mar :25:53pm Mar :35:53pm Mar :45:53pm Mar :55:52pm Mar :05:52pm Mar :15:52pm Mar :25:52pm Mar :35:51pm Mar :45:51pm Mar :55:51pm Mar :05:51pm Mar :15:51pm Mar :25:50pm Mar :35:50pm Mar :45:50pm Mar :55:50pm Mar :05:50pm Mar :15:49pm Mar :25:49pm Mar :35:49pm Mar :45:49pm Mar :55:48pm Mar :05:48pm Mar :15:48pm Mar :25:48pm Mar :35:48pm Mar :45:47pm Mar :55:47pm Mar :05:47pm Mar :15:47pm.000

27 Page 4 of Mar :25:47pm Mar :35:46pm Mar :45:46pm Mar :55:46pm Mar :05:46pm Mar :15:45pm Mar :25:45pm Mar :35:45pm Mar :45:45pm Mar :55:45pm Mar :05:44pm Mar :15:44pm Mar :25:44pm Mar :35:44pm Mar :45:44pm Mar :55:43pm Mar :05:43pm Mar :15:43pm Mar :25:43pm Mar :35:42pm Mar :45:42pm Mar :55:42pm Mar :05:42pm Mar :15:42pm Mar :25:41pm Mar :35:41pm Mar :45:41pm Mar :55:41pm Mar :05:41pm Mar :15:40pm Mar :25:40pm Mar :35:40pm Mar :45:40pm Mar :55:39pm Mar :05:39pm Mar :15:39pm Mar :25:39pm Mar :35:39pm Mar :45:38pm Mar :55:38pm Mar :05:38am Mar :15:38am Mar :25:38am Mar :35:37am Mar :45:37am Mar :55:37am Mar :05:37am Mar :15:36am Mar :25:36am Mar :35:36am Mar :45:36am Mar :55:36am Mar :05:35am Mar :15:35am Mar :25:35am Mar :35:35am Mar :45:34am Mar :55:34am Mar :05:34am.000

28 Page 5 of Mar :15:34am Mar :25:34am Mar :35:33am Mar :45:33am Mar :55:33am Mar :05:33am Mar :15:33am Mar :25:32am Mar :35:32am Mar :45:32am Mar :55:32am Mar :05:31am Mar :15:31am Mar :25:31am Mar :35:31am Mar :45:31am Mar :55:30am Mar :05:30am Mar :15:30am Mar :25:30am Mar :35:30am Mar :45:29am Mar :55:29am Mar :05:29am Mar :15:29am Mar :25:28am Mar :35:28am Mar :45:28am Mar :55:28am Mar :05:28am Mar :15:27am Mar :25:27am Mar :35:27am Mar :45:27am Mar :55:27am Mar :05:26am Mar :15:26am Mar :25:26am Mar :35:26am Mar :45:25am Mar :55:25am Mar :05:25am Mar :15:25am Mar :25:25am Mar :35:24am Mar :45:24am Mar :55:24am Mar :05:24am Mar :15:24am Mar :25:23am Mar :35:23am Mar :45:23am Mar :55:23am Mar :05:22pm Mar :15:22pm Mar :25:22pm Mar :35:22pm Mar :45:22pm Mar :55:21pm.001

29 Page 6 of Mar :05:21pm Mar :15:21pm Mar :25:21pm Mar :35:20pm Mar :45:20pm Mar :55:20pm Mar :05:20pm Mar :15:20pm Mar :25:19pm Mar :35:19pm Mar :45:19pm Mar :55:19pm Mar :05:19pm Mar :15:18pm Mar :25:18pm Mar :35:18pm Mar :45:18pm Mar :55:17pm Mar :05:17pm Mar :15:17pm Mar :25:17pm Mar :35:17pm Mar :45:16pm Mar :55:16pm Mar :05:16pm Mar :15:16pm Mar :25:16pm Mar :35:15pm Mar :45:15pm Mar :55:15pm Mar :05:15pm Mar :15:14pm Mar :25:14pm Mar :35:14pm Mar :45:14pm Mar :55:14pm Mar :05:13pm Mar :15:13pm Mar :25:13pm Mar :35:13pm Mar :45:13pm Mar :55:12pm Mar :05:12pm Mar :15:12pm Mar :25:12pm Mar :35:11pm Mar :45:11pm Mar :55:11pm Mar :05:11pm Mar :15:11pm Mar :25:10pm Mar :35:10pm Mar :45:10pm Mar :55:10pm Mar :05:10pm Mar :15:09pm Mar :25:09pm Mar :35:09pm Mar :45:09pm.001

30 Page 7 of Mar :55:08pm Mar :05:08pm Mar :15:08pm Mar :25:08pm Mar :35:08pm Mar :45:07pm Mar :55:07pm Mar :05:07am Mar :15:07am Mar :25:07am Mar :35:06am Mar :45:06am Mar :55:06am Mar :05:06am Mar :15:05am Mar :25:05am Mar :35:05am Mar :45:05am Mar :55:05am Mar :05:04am Mar :15:04am Mar :25:04am Mar :35:04am Mar :45:04am Mar :55:03am Mar :05:03am Mar :15:03am Mar :25:03am Mar :35:02am Mar :45:02am Mar :55:02am Mar :05:02am Mar :15:02am Mar :25:01am Mar :35:01am Mar :45:01am Mar :55:01am Mar :05:00am Mar :15:00am Mar :25:00am Mar :35:00am Mar :45:00am Mar :54:59am Mar :04:59am Mar :14:59am Mar :24:59am Mar :34:59am Mar :44:58am Mar :54:58am Mar :04:58am Mar :14:58am Mar :24:57am Mar :34:57am Mar :44:57am Mar :54:57am Mar :04:57am Mar :14:56am Mar :24:56am Mar :34:56am.003