Re: Casey Middle School at 1301 High Street in Boulder, Colorado Follow-Up Indoor Air Quality Monitoring (Hydrogen Sulfide)

Transcription

1 April 16, 2014 Mike Cuskelly Boulder Valley School District 6500 Arapahoe, P.O. Box 9011 Boulder, CO Re: Casey Middle School at 1301 High Street in Boulder, Colorado Follow-Up Indoor Air Quality Monitoring (Hydrogen Sulfide) Dear Mr. Cuskelly: At your request, on April 11, 2014, Tony Konowal of Quality Environmental Services & Technologies, Inc. (QUEST) met with school principal Alison Boggs and conducted a follow-up hydrogen sulfide (H 2 S) monitoring assessment 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 follow-up hydrogen sulfide monitoring after recent mitigation efforts, including identification (via smoke testing) and repair of several sewer line leaks, occurred at the school. This report summarizes our site observations, hydrogen sulfide and trace gas monitoring levels, and conclusions. Background Information Site Background Information 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 Ongoing mitigation efforts, including installation of automatic primers for p-traps in floor drains and Studor vents, have been conducted at the school in an attempt to determine and subsequently minimize the source of the odor. In March of 2014, QUEST was retained to monitor the indoor air for hydrogen sulfide in three selected locations where the odor has been intermittently present. As detailed in QUEST s March 18, 2014 Indoor Air Quality Monitoring (Hydrogen Sulfide) report, maximum and average hydrogen sulfide readings in all three locations during the March 7-10 and March 11-14, 2014 monitoring periods were below the published odor and nuisance thresholds as well as below the lowest published hydrogen sulfide exposure limit (ACGIH TLV), with the exception of two readings on March 13, 2014 in Room C201 (between 8:15 and 9:15 a.m.) which did approach and hit the odor threshold of 8 ppb twice, but were still well below the nuisance threshold (40 ppb). Following receipt of QUEST s report, which included recommendations for additional inspection of sewer/plumbing lines associated with the grease interceptor, the District reportedly conducted smoke testing at the school which identified several remaining leaks in sewer/plumbing lines. The District subsequently repaired the leaks and has now

2 Mr. Mike Cuskelly April 16, 2014 Page 2 retained QUEST to conduct follow-up hydrogen sulfide monitoring to assess the effectiveness of the most recently completed mitigation/repair activities. 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 gases. 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 On April 11, 2014, the QUEST representative met with Ms. Boggs and conducted follow-up trace gas monitoring in three locations (originally selected by Ms. Boggs during the March 2014 assessments) 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. QUEST utilized a MultiRAE PGM-6228 photo-ionization chemical detector to measure airborne concentrations of carbon monoxide (ppm), combustible gasses (% LEL), hydrogen sulfide (ppm), oxygen (%), and total volatile organic compounds (ppm) No hydrogen sulfides or combustible gasses LEL were detected in any indoor locations, and all tested locations contained 20.9% oxygen. Outside of the building, the detected total volatile organic compounds (TVOC) concentration ranged between 0.0 and 0.1 ppm. Only a very low, background concentration of TVOCs (0.1 ppm) was detected in the three indoor locations. The detected TVOC level is well below published recommendations for maximum indoor TVOC levels. International consensus for recommended indoor TVOC concentrations ranges between 0.1 and ppm. RAE Systems (a well-known manufacturer of gas detection systems) field experience suggests normal outdoor air contains <0.1 ppm;

3 Mr. Mike Cuskelly April 16, 2014 Page 3 normal indoor air contains ppm; and indoor air containing >0.5 ppm indicates potential for TVOC contamination. A 1990 study by Mølhave et al. (Volatile organic compounds, indoor air quality and health), which is considered a generally accepted guideline on indoor TVOC exposure and human health responses, recommends TVOCs not exceed 1.0 ppm. The detected TVOC level is therefore well below published recommendations for maximum indoor TVOC levels. In summary, all of the detected concentrations are well within normal and expected ranges, with no anomalies detected. From the late morning of Friday, April 11 to the early afternoon of Monday, April 14, 2014 the QUEST representative conducted a follow-up 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 75 hours. During the initial assessments, Ms. Boggs reported that the odors are most noticeable on Monday mornings, and as such, this assessment was conducted to include Monday morning monitoring. At the time of hydrogen sulfide detection monitor placement on April 11, 2014, the QUEST representative did not detect a sewer gas or any other odor inside or outside the school in the areas of concern. However, on April 14, 2014, at the time of hydrogen sulfide monitor pick-up, the QUEST representative did detect a sewer gas / grease interceptor-like odor at the front entrance (east side) of the school. During the follow-up monitoring period, 452 readings were collected in Room C140, 451 readings were collected in Room C201, and 450 readings were collected in Room B360. On April 14, 2014, the QUEST representative retrieved the three hydrogen sulfide monitors from the school and then downloaded the data. The data was analyzed on April 16, 2014 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 and graphs. 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. Date Room Max. H2S Reading Avg. H2S Reading H2S Odor Threshold H2S Nuisance Threshold Lowest of the available OSHA PEL, ACGIH TLV, NIOSH REL April 11-14, 2014 C140 1 ppb 0 ppb 8 ppb 40 ppb 1,000 ppb C201 4 ppb 1 ppb 8 ppb 40 ppb 1,000 ppb B360 4 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. Due to sampling variability (samples were taken every ten minutes), it is possible that hydrogen sulfide

4 Mr. Mike Cuskelly April 16, 2014 Page 4 concentrations may have exceeded the odor threshold at the other times, but were simply not recorded. No hydrogen sulfide was detected in C140 throughout the entire 75 hour monitoring period, with the exception of a single 1 ppb reading at 9:11 a.m. on Monday (April 14, 2014). In C201 and B360, generally, the highest concentrations of hydrogen sulfide (all 4 ppb) were identified during school hours on Friday (April 11, 2014) and Monday (April 14, 2014), with slightly higher concentrations identified during the Friday (April 11, 2014) monitoring as compared to the Monday (April 14, 2014) monitoring results. In addition, hydrogen sulfide concentrations were consistently lower in C201 and B360 during weekend (April 12 and 13, 2014) monitoring. As compared to hydrogen sulfide concentrations identified during the March 2014 assessments, average concentrations identified during the follow-up assessment were identical in all three testing locations, however, maximum hydrogen sulfide concentrations were found to be lower in all three testing locations with no odor threshold exceedances. In summary, the hydrogen sulfide concentrations identified in the three locations sampled at Casey Middle School during the April 11-14, 2014 monitoring period did not indicate any odor or safety concerns for building occupants and thus the recent mitigation steps taken by the District appear to have reduced indoor hydrogen sulfide levels at Casey Middle School. Conclusions Based on QUEST s follow-up hydrogen sulfide detection and trace gas monitoring assessments, conducted from April 11 th to 14 th, 2014, in three areas of concern inside Casey Middle School, we provide the following conclusions: 1. Recent smoke testing of the school s sewer/plumbing lines identified several leaks that have now been repaired; 2. On April 14, 2014, at the time of hydrogen sulfide monitor pick-up, the QUEST representative did detect a sewer gas / grease interceptor-like odor at the front entrance (east side) of the school; no odors were detected inside or outside the school at the time of hydrogen sulfide monitor placement on April 11, 2014; 3. During trace gas monitoring on April 11, 2014 (in Rooms C140, C201, and B360), the detected concentrations of TVOCs and oxygen were well within normal and expected values. No carbon monoxide, hydrogen sulfide (ppm), or combustible gasses LEL were detected; 4. Maximum and average hydrogen sulfide readings in all three locations during the April 11-14, 2014 monitoring periods were below the published odor and nuisance thresholds as well as below the lowest published hydrogen sulfide exposure limit (ACGIH TLV); 5. No hydrogen sulfide was detected in C140 throughout the entire 75 hour monitoring period, with the exception of a single 1 ppb reading at 9:11 a.m. on Monday (April 14, 2014);

5 Mr. Mike Cuskelly April 16, 2014 Page 5 6. In C201 and B360, generally, the highest concentrations of hydrogen sulfide (all 4 ppb) were identified during school hours on Friday (April 11, 2014) and Monday (April 14, 2014), with slightly higher concentrations identified during the Friday (April 11, 2014) monitoring as compared to the Monday (April 14, 2014) monitoring results. Hydrogen sulfide concentrations were consistently lower in C201 and B360 during weekend (April 12 and 13, 2014) monitoring; 7. As compared to hydrogen sulfide concentrations identified during the March 2014 assessments, average concentrations identified during the follow-up assessment were identical in all three testing locations, however, maximum hydrogen sulfide concentrations were found to be lower in all three testing locations with no odor threshold exceedances; 8. In summary, the hydrogen sulfide concentrations identified in the three locations sampled at Casey Middle School during the April 11-14, 2014 monitoring period did not indicate any odor or safety concerns for building occupants and thus the recent mitigation steps taken by the District appear to have reduced indoor hydrogen sulfide levels at Casey Middle School; 9. If requested, QUEST would be pleased to conduct additional sampling and assessments. 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 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: April 11-14, 2014 Graphs and Data Reports & H2S Analyzer Certs. of Calibration

6 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: Apr :29pm Alarm Setpoint: 0 (ppm) Result (ppm) Apr-11 12AM Apr-11 12PM Apr-12 12AM Apr-12 12PM Apr-13 12AM Apr-13 12PM Apr-14 12AM Apr-14 12PM Apr-15 12AM Day

7 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: Apr :29pm Alarm Setpoint: 0 (ppm) DATE/TIME RESULT (ppm) Page 1 of 8 1 Apr :12:38am Apr :23:08am Apr :33:08am Apr :43:08am Apr :53:07am Apr :03:07pm Apr :13:07pm Apr :23:07pm Apr :33:07pm Apr :43:07pm Apr :53:06pm Apr :03:06pm Apr :13:06pm Apr :23:06pm Apr :33:06pm Apr :43:05pm Apr :53:05pm Apr :03:05pm Apr :13:05pm Apr :23:05pm Apr :33:05pm Apr :43:04pm Apr :53:04pm Apr :03:04pm Apr :13:04pm Apr :23:04pm Apr :33:03pm Apr :43:03pm Apr :53:03pm Apr :03:03pm Apr :13:03pm Apr :23:03pm Apr :33:02pm Apr :43:02pm Apr :53:02pm Apr :03:02pm Apr :13:02pm Apr :23:01pm Apr :33:01pm Apr :43:01pm Apr :53:01pm Apr :03:01pm Apr :13:01pm Apr :23:00pm Apr :33:00pm Apr :43:00pm Apr :53:00pm Apr :03:00pm Apr :13:00pm.000

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15 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: Apr :45pm Alarm Setpoint: 0 (ppm) Result (ppm) Apr-11 12AM Apr-11 12PM Apr-12 12AM Apr-12 12PM Apr-13 12AM Apr-13 12PM Apr-14 12AM Apr-14 12PM Apr-15 12AM Day

16 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: Apr :45pm Alarm Setpoint: 0 (ppm) DATE/TIME RESULT (ppm) Page 1 of 8 1 Apr :18:50am Apr :29:20am Apr :39:20am Apr :49:20am Apr :59:19am Apr :09:19pm Apr :19:19pm Apr :29:19pm Apr :39:19pm Apr :49:18pm Apr :59:18pm Apr :09:18pm Apr :19:18pm Apr :29:18pm Apr :39:18pm Apr :49:17pm Apr :59:17pm Apr :09:17pm Apr :19:17pm Apr :29:17pm Apr :39:16pm Apr :49:16pm Apr :59:16pm Apr :09:16pm Apr :19:16pm Apr :29:16pm Apr :39:15pm Apr :49:15pm Apr :59:15pm Apr :09:15pm Apr :19:15pm Apr :29:15pm Apr :39:14pm Apr :49:14pm Apr :59:14pm Apr :09:14pm Apr :19:14pm Apr :29:13pm Apr :39:13pm Apr :49:13pm Apr :59:13pm Apr :09:13pm Apr :19:13pm Apr :29:12pm Apr :39:12pm Apr :49:12pm Apr :59:12pm Apr :09:12pm Apr :19:12pm.002

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21 Page 6 of Apr :48:29am Apr :58:29am Apr :08:29am Apr :18:29am Apr :28:29am Apr :38:28am Apr :48:28am Apr :58:28am Apr :08:28pm Apr :18:28pm Apr :28:28pm Apr :38:27pm Apr :48:27pm Apr :58:27pm Apr :08:27pm Apr :18:27pm Apr :28:26pm Apr :38:26pm Apr :48:26pm Apr :58:26pm Apr :08:26pm Apr :18:26pm Apr :28:25pm Apr :38:25pm Apr :48:25pm Apr :58:25pm Apr :08:25pm Apr :18:25pm Apr :28:24pm Apr :38:24pm Apr :48:24pm Apr :58:24pm Apr :08:24pm Apr :18:23pm Apr :28:23pm Apr :38:23pm Apr :48:23pm Apr :58:23pm Apr :08:23pm Apr :18:22pm Apr :28:22pm Apr :38:22pm Apr :48:22pm Apr :58:22pm Apr :08:22pm Apr :18:21pm Apr :28:21pm Apr :38:21pm Apr :48:21pm Apr :58:21pm Apr :08:20pm Apr :18:20pm Apr :28:20pm Apr :38:20pm Apr :48:20pm Apr :58:20pm Apr :08:19pm Apr :18:19pm Apr :28:19pm.001

22 Page 7 of Apr :38:19pm Apr :48:19pm Apr :58:18pm Apr :08:18pm Apr :18:18pm Apr :28:18pm Apr :38:18pm Apr :48:18pm Apr :58:17pm Apr :08:17pm Apr :18:17pm Apr :28:17pm Apr :38:17pm Apr :48:17pm Apr :58:16pm Apr :08:16pm Apr :18:16pm Apr :28:16pm Apr :38:16pm Apr :48:15pm Apr :58:15pm Apr :08:15am Apr :18:15am Apr :28:15am Apr :38:15am Apr :48:14am Apr :58:14am Apr :08:14am Apr :18:14am Apr :28:14am Apr :38:14am Apr :48:13am Apr :58:13am Apr :08:13am Apr :18:13am Apr :28:13am Apr :38:12am Apr :48:12am Apr :58:12am Apr :08:12am Apr :18:12am Apr :28:12am Apr :38:11am Apr :48:11am Apr :58:11am Apr :08:11am Apr :18:11am Apr :28:11am Apr :38:10am Apr :48:10am Apr :58:10am Apr :08:10am Apr :18:10am Apr :28:09am Apr :38:09am Apr :48:09am Apr :58:09am Apr :08:09am Apr :18:09am.000

23 Page 8 of Apr :28:08am Apr :38:08am Apr :48:08am Apr :58:08am Apr :08:08am Apr :18:07am Apr :28:07am Apr :38:07am Apr :48:07am Apr :58:07am Apr :08:07am Apr :18:06am Apr :28:06am Apr :38:06am Apr :48:06am Apr :58:06am Apr :08:06am Apr :18:05am Apr :28:05am Apr :38:05am Apr :48:05am Apr :58:05am Apr :08:04am Apr :18:04am Apr :28:04am Apr :38:04am Apr :48:04am Apr :58:04am Apr :08:03am Apr :18:03am Apr :28:03am Apr :38:03am Apr :48:03am Apr :58:03am Apr :08:02pm Apr :18:02pm Apr :28:02pm Apr :38:02pm Apr :48:02pm Apr :58:01pm Apr :08:01pm Apr :18:01pm Apr :28:01pm Apr :38:01pm Apr :48:01pm Apr :58:00pm Apr :08:00pm Apr :18:00pm.000 Readings: 451 Minimum: 0 Maximum: Average: SD:

24 Site Name: Address: BVSD; Casey Middle School Sample Location: #3 (B360) Technician: Mr Brown Instrument: Jim's 631, 631-X, SN 1004 Comment: Date/Time: Apr :54pm Alarm Setpoint: 0 (ppm) Result (ppm) Apr-11 12AM Apr-11 12PM Apr-12 12AM Apr-12 12PM Apr-13 12AM Apr-13 12PM Apr-14 12AM Apr-14 12PM Apr-15 12AM Day

25 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: Apr :54pm Alarm Setpoint: 0 (ppm) DATE/TIME RESULT (ppm) Page 1 of 8 1 Apr :23:38am Apr :34:08am Apr :44:08am Apr :54:08am Apr :04:08pm Apr :14:08pm Apr :24:07pm Apr :34:07pm Apr :44:07pm Apr :54:07pm Apr :04:06pm Apr :14:06pm Apr :24:06pm Apr :34:06pm Apr :44:06pm Apr :54:05pm Apr :04:05pm Apr :14:05pm Apr :24:05pm Apr :34:05pm Apr :44:04pm Apr :54:04pm Apr :04:04pm Apr :14:04pm Apr :24:03pm Apr :34:03pm Apr :44:03pm Apr :54:03pm Apr :04:03pm Apr :14:02pm Apr :24:02pm Apr :34:02pm Apr :44:02pm Apr :54:01pm Apr :04:01pm Apr :14:01pm Apr :24:01pm Apr :34:01pm Apr :44:00pm Apr :54:00pm Apr :04:00pm Apr :14:00pm Apr :24:00pm Apr :33:59pm Apr :43:59pm Apr :53:59pm Apr :03:59pm Apr :13:58pm Apr :23:58pm.002

26 Page 2 of 8 50 Apr :33:58pm Apr :43:58pm Apr :53:58pm Apr :03:57pm Apr :13:57pm Apr :23:57pm Apr :33:57pm Apr :43:57pm Apr :53:56pm Apr :03:56pm Apr :13:56pm Apr :23:56pm Apr :33:55pm Apr :43:55pm Apr :53:55pm Apr :03:55pm Apr :13:55pm Apr :23:54pm Apr :33:54pm Apr :43:54pm Apr :53:54pm Apr :03:54pm Apr :13:53pm Apr :23:53pm Apr :33:53pm Apr :43:53pm Apr :53:52pm Apr :03:52am Apr :13:52am Apr :23:52am Apr :33:52am Apr :43:51am Apr :53:51am Apr :03:51am Apr :13:51am Apr :23:51am Apr :33:50am Apr :43:50am Apr :53:50am Apr :03:50am Apr :13:49am Apr :23:49am Apr :33:49am Apr :43:49am Apr :53:49am Apr :03:48am Apr :13:48am Apr :23:48am Apr :33:48am Apr :43:48am Apr :53:47am Apr :03:47am Apr :13:47am Apr :23:47am Apr :33:46am Apr :43:46am Apr :53:46am Apr :03:46am Apr :13:46am.000

27 Page 3 of Apr :23:45am Apr :33:45am Apr :43:45am Apr :53:45am Apr :03:44am Apr :13:44am Apr :23:44am Apr :33:44am Apr :43:44am Apr :53:43am Apr :03:43am Apr :13:43am Apr :23:43am Apr :33:43am Apr :43:42am Apr :53:42am Apr :03:42am Apr :13:42am Apr :23:41am Apr :33:41am Apr :43:41am Apr :53:41am Apr :03:41am Apr :13:40am Apr :23:40am Apr :33:40am Apr :43:40am Apr :53:40am Apr :03:39am Apr :13:39am Apr :23:39am Apr :33:39am Apr :43:38am Apr :53:38am Apr :03:38am Apr :13:38am Apr :23:38am Apr :33:37am Apr :43:37am Apr :53:37am Apr :03:37pm Apr :13:37pm Apr :23:36pm Apr :33:36pm Apr :43:36pm Apr :53:36pm Apr :03:35pm Apr :13:35pm Apr :23:35pm Apr :33:35pm Apr :43:35pm Apr :53:34pm Apr :03:34pm Apr :13:34pm Apr :23:34pm Apr :33:34pm Apr :43:33pm Apr :53:33pm Apr :03:33pm.001

28 Page 4 of Apr :13:33pm Apr :23:32pm Apr :33:32pm Apr :43:32pm Apr :53:32pm Apr :03:32pm Apr :13:31pm Apr :23:31pm Apr :33:31pm Apr :43:31pm Apr :53:31pm Apr :03:30pm Apr :13:30pm Apr :23:30pm Apr :33:30pm Apr :43:29pm Apr :53:29pm Apr :03:29pm Apr :13:29pm Apr :23:29pm Apr :33:28pm Apr :43:28pm Apr :53:28pm Apr :03:28pm Apr :13:28pm Apr :23:27pm Apr :33:27pm Apr :43:27pm Apr :53:27pm Apr :03:26pm Apr :13:26pm Apr :23:26pm Apr :33:26pm Apr :43:26pm Apr :53:25pm Apr :03:25pm Apr :13:25pm Apr :23:25pm Apr :33:24pm Apr :43:24pm Apr :53:24pm Apr :03:24pm Apr :13:24pm Apr :23:23pm Apr :33:23pm Apr :43:23pm Apr :53:23pm Apr :03:23pm Apr :13:22pm Apr :23:22pm Apr :33:22pm Apr :43:22pm Apr :53:21pm Apr :03:21am Apr :13:21am Apr :23:21am Apr :33:21am Apr :43:20am Apr :53:20am.000