|
We conducted our first water sampling on the 30 November 2006,
still very early in the maturation of the wetland system. We
only looked at four indicators: zinc, copper nitrogen and fecal
coliform bacteria. These tests were carried out at the Angostura
Environmental Laboratory and at the Water and Sewage Authority
(WASA). The results were very encouraging. Samples were taken
at the start of the main drain upstream of the development and
at the storm water outlet at the very end of the wetland system.
The findings were:
|
|
Head water |
Wetland outfall |
|
Zinc |
0.005 ppm |
0.003 ppm |
|
Copper |
0.004 ppm |
0.001 ppm |
|
Nitrogen |
0.327 ppm |
0.109 ppm |
|
Fecal Coliform |
340 no. |
62 no. |
|
Five Day Fecal Coliform |
1.0 ml |
0.4 ml |
The level of zinc was reduced by 40%, the level of copper
reduced by 75%, the level of nitrogen reduced by 67%, fecal coliform
reduced by 91%, and the five day fecal coliform reduced by 62%.
The significant thing about these results is that the wetland
is not yet fully established. Further tests will measure exactly
where the reductions are being made. By the end of 2007 we will
also be testing for levels of phosphates, lead, BOD, dissolved
solids and much more.
The other key and perhaps equally important result is that
the additional cost was fully recovered in higher real estate
values, well in excess of the forecast. |