Environmental Engineering Reference
In-Depth Information
Ottawa Summer 2007 post-rehab first liter samples before and
after pH adjustment
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
1
2
3
4
5
6
7
8
9
10
11
no of samples
Ottawa Summer with no pH adjustment
Ottawa Summer with pH adjusted to 7.4
Fig. 11.6 Ottawa summer post rehab 2007 first liter samples before and after pH adjustment
Ottawa first liter samples before and after pH adjustment
16.0
Spring 2007
Summer pre rehab 2007
Summer post rehab 2007
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
No of samples
Ottawa Sample before pH adjustment
Ottawa sample after pH adjustment (pH=7.4)
Fig. 11.7 Ottawa
first liter samples (all) before and after pH adjustment
Prior to the pH adjustment, Ottawa had no
first liter samples over 10
g/L. After
μ
the pH adjustment (i.e. adjusted lead values to pH = 7.4), Ottawa had
five samples
over 10
g/L in Spring 2007, two samples in Summer pre-water main rehab 2007
and no samples in Summer post water main rehab 2007.
One anomaly in the Ottawa data is that Spring 2007
μ
first liter samples showed
higher lead values than Summer (pre- and post-water main rehab) 2007 samples
even before the pH adjustment although temperature should increase the rate of
dissolution of lead. Location can be a reason for this as each home plumbing system
is unique and will produce different results depending on many internal plumbing
factors. Another reason could be due to temperature itself. We would expect higher
temperature in the summer (average for Ottawa data is 22.6 C) to be associated with
higher lead values in water samples and lower temperature in spring (average for
the Ottawa data is 2.2 C) with lower lead values. However, since we are examining
the
first liter only, that sample would be taken from the internal plumbing within the
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