HERE ARE THE FACTS: As seen in the Average Sewage Flow Chart (Figure 2.1)*, below, influent flows to the lagoons in March-April-May are traditionally about 300 % higher than September flows. This huge differential is largely due to groundwater infiltration (into the sewer-pipe collector system), when water-tables are highest in the spring thaw. The sewer collector pipe-sealing program (circa 1993), did not have a lasting benefit, as infiltration increases with system age.
*(Figure 2.1, from
the Totten-Simms Hubicki (1996) Environmental Study Report-ESR, was removed
from the Region's Evidence copy of the ESR, at the OMB, but was reintroduced
as Evidence, by the
Appellants.) |
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| Several qualified engineers agreed, in their evidence at the OMB hearing, that such extreme fluctuations in flows negate the use of an 8-inch or 10-inch forcemain (as proposed), without the combined use of one or more lagoons, on a year-round basis. That's the bottom line. Solids have to be kept moving. At flow rates (in an 8' pipe) below 20'/second, solids can begin to adhere to inside of the pipeline, building-up and restricting flow. The fixed pipe size does not allow for the wide extremes in flow (as shown in Fig. 2.1, above), and will, therefore, be too small for peak flows, and will not be able to maintain the necessary, minimum-flow velocity during the low-flow periods: It's a problematic, 'Catch-22' ...without full-time use of lagoons. (To review one example of huge cost to taxpayers, for the City's errors in not keeping sewage moving, look at the $17,000,000-"mistake" with the Walkley collector: CLICK HERE). Also, with a pipeline, maintenance requirements and costs would be heavy ...necessitating frequent periods of total flow storage, while repairs proceeded ...Goulbourn Township's engineer, Michael Pinet, P.Eng. stated:
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