The earlier work was done for practice in getting familiar with techniques, and that site was below the tennis courts (see maps representing 2 different days of anayses). Site 8 was considered as an actual testing site.
Site 8 consists of ~80 meters of 4-Pole Creek including 3 drain pipes, beginning below the Rose Garden and ending at the 8th street bridge. Since my original objective was to test for and quantify fecal contamination as a health issue, I was interested in the fecal levels in the creek itself and in the effluent flowing into the creek from drain pipes. I was also interested in any impact from drain pipe effluent on coliform levels downstream. I was told that the EPA has an interest in impacts such as this also. From the creek itself, I got coliform levels in the thousands per deciliter. The levels from samples taken upsteam from all the pipes were about the same as those below the pipes (samples taken under the bridge), so we concluded that the pipe C, the only one of the pipes that had coliforms, did not cause downstream levels of coliforms to be any higher than site #1 (upstream), and therefore had a low level of negative impact. I have shown proof via biochemical tests (see photos of these tests in the blog) that both in the creek and in effluent from pipe C, that Escherichia coli was present among the coliforms counted on my plates. This proves that the coliforms I detected are fecal since Escherichia coli is found only in feces, and not in the environment. As I have mentioned earlier, I used Fmc medium in all of the testing, because it selects out gram negative bacteria only, and only lactose fermenters will be blue on this medium, and those will be the coliforms which I counted.
Drain pipes:
We labeled the 3 drain pipes A, B, and C (see map of site 8). We got 0 coliforms from both A or B from 2 different test times. We didn't test them further because they did not present a health problem. We noticed 2 things about pipes A and B, though. One is that they drained briefly when it rained, and stopped draining soon after the rain stopped. We theorized that they drained the surface water from 8th street and not any underground sources, because of the short duration of effluent. Also, when I accidentally left the sampling plates at ambient instead of 44.5C, we noticed very high levels of environmental bacteria, which are found mostly in the top levels of soil, and deeper soils such as deeper drainage systems have few or no bacteria from the soil itself.
Pipe C was the most important focus of my testing. It ran all the time, ranging from about 1 or 2 liters/min. to something over 10 liters/min. It was hard to determine because I wasn't allowed to sample during flood stage because of the danger of falling in and being carried away. Even during normal levels, I had to crawl down to the outlet of Pie C as you can see in the photo for April 5 on the blog site.
We found 2 important things about Pipe C. One was that the effluent from it contained coliforms in significant levels. We tested it again and again under different weather conditions, because sometimes we got coliform levels lower than he creek itself, and occasionally we got higher levels. Also, sometimes we saw a lot of detergent foam (white), but not every day, more like every few days. We theorized that either pipe C drained surface water and the detergent was from someone washing his car, or pipe C represents underground storm drainage and then picks up effluent from broken sewer lines. This latter theory is more likely since it contains significant levels of coliforms, and it drains constantly, instead of just when it rains.
In terms of the health hazard issue, wherever coliforms are found there is the danger of the spread of fecal-oral diseases, as I mentioned early in this blog. There are several bacterial, parasitic, and viral diseases spread this way, and they are all serious and sometimes fatal, but I have found during this work that fecal contamination is almost everywhere. So, where do you draw the line as to what represents a dangerous situation vs. a tolerable one. I have learned also during this work that the "lines" that are drawn vary a lot. Drinking water shall contain 0 coliforms to be safe. Public swimming areas (non-chlorinated) are temporarily shut down when possibly 300 cfu's coliforms per deciliter are found, or maybe 100/dl, depending on health dept. recommendations, or state regulations vs. federal regs. such as state parks vs. national parks. No one knows all the 'right" answers on this issue.
Next Site:
Since I have one third of the semester left to work, I would like to do another project on Four Pole. I see a couple of possibilities:
1. A large drain empties into 4-Pole a few feet upstream from the bridge to the tennis court area. It always has a strong flow, and it would be interesting to see if it contributes fecal coliforms, and if so at what level. Also what impact would it have as the stream continues through the park.
2. Measure influence of totality of drains from country homes a half mile or more upstream to see what fecal levels occur there vs the levels as the stream travels through the park and picks up fecal contamination as we have seen from Pipe C at area 8.
No comments:
Post a Comment