City of Prince George - Snow Disposal at the Lansdowne Road ...

maximum snow melting rate according to the regression equation is 123 tonnes/hr, or 2,900
tonnes per 24 hour day. The number of days (assuming 24 hour operation) to dispose of the
collected snow from the annual minimum, annual mean, and annual maximum snowfalls for
present and future plant flow rates were estimated from the snow melting regression equation,
and the results are summarized in Table 5 (note that the hourly flow rate based on the present
day flow is 1,390 m 3 /hr, and the future hourly flow rate based on the average day flow is
approximately 1,900 m 3 /hr - the regression was assumed to be linear beyond the highest
average hourly flow rate of 1,350 m 3 /hr used in the regression).
TABLE 5
SNOW DISPOSAL CAPACITY OF THE WWTC
Number of Days Required to Dispose of Collected Snow
Minimum Snowfall Mean Snowfall Maximum
Present Future Present Future Present Future
Melting 38 29 53 42 76 60
Effluent TSS 45 42 64 61 91 87
The theoretical calculation of plant melting capacity carried out in Section 4.1 can be applied to
determine the additional melting capacity that would be realized from a greater temperature
drop between the tank influent and effluent than was observed during the test (assuming that
the mixing power in the tank were increased to allow a faster rate of snow addition). If the
mean temperature of the chlorine tank influent were lowered from 11 degrees C to say 3
degrees C by snow additions, repeating the rough calculation described in Section 4.1 shows
that the melting capacity of the WWTC at the average daily flow of 33,400 m 3 /d would
increase from 96 tonnes per hour to 125 tonnes per hour, an increase of 30%. The theoretical
calculation shows that the melting capacity of the WWTC during the test was not limited by the
available heat energy in the chlorine tank effluent. In general, the factors determining the
melting capacity of the WWTC will be the temperature of the chlorine tank influent, the
temperature of the snow added to the tank, and the tank mixing capacity. The melting capacity
of the plant shown in Table 5 applies only to the conditions under which the test was
conducted. The melting capacity will increase with an increasing temperature drop between
the chlorine tank influent and effluent. An increase in mixing power in the tank should also
increase the melting capacity, since the melting rate during the test was limited by the capacity
of the tank mixers to circulate the added snow.
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