Manganese Update 7/28/06
Manganese Sampling Update
July 28, 2006
Summary
The Water Utility has now collected and analyzed 998 household samples for manganese in the Well 3, Well 8, Well 10, and Well 29 flushing areas, which are the four wells producing the highest levels of manganese in our water system. This is about 80% of the total number of household samples we expect to collect during the flushing program in these areas. The results continue to show low levels of manganese at household taps (taken at outside hose-bib spigots). 90% of all samples were below the EPA aesthetic recommendation for drinking water of 50 parts per billion (ppb). 10% of the samples were above 50 ppb. 11 of the 998 samples (1.3%) were above the EPA lifetime health advisory level of 300 ppb.
The 11 samples containing more than 300 ppb manganese were collected at 8 sites. None of these 8 sites was found to have water consistently above 300 ppb manganese. Further details about these samples can be found in the table included with this report.
Based on these results, Dr. Thomas Schlenker, Director of Public Health for Madison and Dane County rescinded the limited health advisory for infants and persons with liver disease in the Well 3 and Well 10 areas on July 17. Dr. Schlenker said, “levels of manganese that have been and are being measured indicate that tap water is acceptable for daily consumption for the entire population.”
Well 3 Flushing Area
The Utility has completed flushing in the Well 3 service area. We have received the lab results of 361 samples from its post-flushing sampling in the area. We anticipate taking a total of about 400 post-flushing samples in this flushing area. All samples are taken at randomly selected sites in the area from hose-bib spigots.
300 out of the 361 samples (83%) were below 50 parts per billion (ppb), the EPA aesthetic guideline for drinking water. 55 out of the 361 samples (15%) were between 50 and 300 ppb. Six samples (1.7%) were above the 300 ppb EPA Lifetime Health Advisory Level for drinking water.
The 6 samples containing more than 300 ppb manganese were collected at 4 sites. None of these 4 sites was found to have water consistently above 300 ppb manganese. Further details about these samples can be found in the table included with this report.
Well 10 Flushing Area
Flushing operations continue in the Well 10 area. Over 200 samples were taken randomly at households in this area prior to start of the flushing operation, and the same households are being re-sampled one to three weeks after flushing is completed on their streets and will be re-sampled again 30 days after flushing.
Out of 286 pre- and post-flush samples collected, 271 samples (95%) were below 50 ppb, and 14 samples (5%) were between 50 and 300 ppb. One sample above 300 ppb was re-sampled four times at levels of 3 ppb, 57 ppb, 11 ppb and 3 ppb.*
78 of the 286 samples were collected after the water mains were flushed. 74 of these 78 (95%) were below 50 ppb. The two highest results were 96 and 127 ppb, both of which were probably influenced by nearby flushing; follow-up samples will be taken to confirm that this is the case.
Well 29 Flushing Area
The Utility has completed flushing in the Well 29 area. About 300 samples were collected following flushing, 257 of which have been analyzed. 241 of the 257 samples (94%) were below 50 ppb. 14 of the 257 samples (5.4%) were between 50 ppb and 300 ppb. Two samples (0.8%) were above 300 ppb and were re-sampled. One very highly discolored sample (10,100 ppb) cleared up quickly upon running the tap and re-sampled at 64 ppb.* Three more follow-up samples showed levels of 19, 6 and 9 ppb. The other site tested initially at 441 ppb, with follow-up samples of 4, 20 and 6 ppb.
Well 8 Flushing Area
The Utility has completed flushing in the Well 8 area. 94 post-flush samples have been collected and analyzed. 83 of the 94 samples (88%) were below 50 ppb. 9 of the 94 samples (10%) were between 50 ppb and 300 ppb. Two samples, both from the same site, measured over 300 at levels of 335 ppb and 1530 ppb.* These samples were taken from a basement tap that had apparently not been used in months or years. A sample from a more frequently-used tap in the same building measured 31 ppb.
* Temporary, short-term elevation of manganese at the tap may be caused by a variety of situations. In a number of cases, we are finding the high readings came from hose-bib spigots that had not been used frequently, allowing sediment to accumulate in a way that would not happen in taps used regularly. Short-term elevation may also be caused by a temporary hydraulic disturbance in the water distribution system. In each case where a sample result is above 300 ppb, the Utility is investigating to try to determine the reason for the short-term elevation.
July 28, 2006
Summary
The Water Utility has now collected and analyzed 998 household samples for manganese in the Well 3, Well 8, Well 10, and Well 29 flushing areas, which are the four wells producing the highest levels of manganese in our water system. This is about 80% of the total number of household samples we expect to collect during the flushing program in these areas. The results continue to show low levels of manganese at household taps (taken at outside hose-bib spigots). 90% of all samples were below the EPA aesthetic recommendation for drinking water of 50 parts per billion (ppb). 10% of the samples were above 50 ppb. 11 of the 998 samples (1.3%) were above the EPA lifetime health advisory level of 300 ppb.
The 11 samples containing more than 300 ppb manganese were collected at 8 sites. None of these 8 sites was found to have water consistently above 300 ppb manganese. Further details about these samples can be found in the table included with this report.
Based on these results, Dr. Thomas Schlenker, Director of Public Health for Madison and Dane County rescinded the limited health advisory for infants and persons with liver disease in the Well 3 and Well 10 areas on July 17. Dr. Schlenker said, “levels of manganese that have been and are being measured indicate that tap water is acceptable for daily consumption for the entire population.”
Well 3 Flushing Area
The Utility has completed flushing in the Well 3 service area. We have received the lab results of 361 samples from its post-flushing sampling in the area. We anticipate taking a total of about 400 post-flushing samples in this flushing area. All samples are taken at randomly selected sites in the area from hose-bib spigots.
300 out of the 361 samples (83%) were below 50 parts per billion (ppb), the EPA aesthetic guideline for drinking water. 55 out of the 361 samples (15%) were between 50 and 300 ppb. Six samples (1.7%) were above the 300 ppb EPA Lifetime Health Advisory Level for drinking water.
The 6 samples containing more than 300 ppb manganese were collected at 4 sites. None of these 4 sites was found to have water consistently above 300 ppb manganese. Further details about these samples can be found in the table included with this report.
Well 10 Flushing Area
Flushing operations continue in the Well 10 area. Over 200 samples were taken randomly at households in this area prior to start of the flushing operation, and the same households are being re-sampled one to three weeks after flushing is completed on their streets and will be re-sampled again 30 days after flushing.
Out of 286 pre- and post-flush samples collected, 271 samples (95%) were below 50 ppb, and 14 samples (5%) were between 50 and 300 ppb. One sample above 300 ppb was re-sampled four times at levels of 3 ppb, 57 ppb, 11 ppb and 3 ppb.*
78 of the 286 samples were collected after the water mains were flushed. 74 of these 78 (95%) were below 50 ppb. The two highest results were 96 and 127 ppb, both of which were probably influenced by nearby flushing; follow-up samples will be taken to confirm that this is the case.
Well 29 Flushing Area
The Utility has completed flushing in the Well 29 area. About 300 samples were collected following flushing, 257 of which have been analyzed. 241 of the 257 samples (94%) were below 50 ppb. 14 of the 257 samples (5.4%) were between 50 ppb and 300 ppb. Two samples (0.8%) were above 300 ppb and were re-sampled. One very highly discolored sample (10,100 ppb) cleared up quickly upon running the tap and re-sampled at 64 ppb.* Three more follow-up samples showed levels of 19, 6 and 9 ppb. The other site tested initially at 441 ppb, with follow-up samples of 4, 20 and 6 ppb.
Well 8 Flushing Area
The Utility has completed flushing in the Well 8 area. 94 post-flush samples have been collected and analyzed. 83 of the 94 samples (88%) were below 50 ppb. 9 of the 94 samples (10%) were between 50 ppb and 300 ppb. Two samples, both from the same site, measured over 300 at levels of 335 ppb and 1530 ppb.* These samples were taken from a basement tap that had apparently not been used in months or years. A sample from a more frequently-used tap in the same building measured 31 ppb.
* Temporary, short-term elevation of manganese at the tap may be caused by a variety of situations. In a number of cases, we are finding the high readings came from hose-bib spigots that had not been used frequently, allowing sediment to accumulate in a way that would not happen in taps used regularly. Short-term elevation may also be caused by a temporary hydraulic disturbance in the water distribution system. In each case where a sample result is above 300 ppb, the Utility is investigating to try to determine the reason for the short-term elevation.
posted by Brenda Konkel at
12:14 PM
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