Blackburn Wastewater Treatment Plant Upgrade Study

SECTION 3.0
AUDIT OF EXISTING FACILITIES
3.1 BLACKBURN WASTEWATER TREATMENT PLANT
The Blackburn WWTP is adjacent to Foreman Road and treats wastewater
from the Prince George Airport, Airport Hill, Aitcheson and Blackbum areas.
The plant was constructed in 1976 for a design population of 2,500, and
consists of an inlet works, two aerated lagoons with coarse bubble aeration,
and a chlorination facility. h e plant is presently close to both its design
hydraulic and organic loading capacity. Its hydraulic capacity is often
exceeded during wet weather and winterkpring thaw conditions, which
contribute high levels of III to the wastewater flows. Emuent quality is also
impacted during the spring to summer transition as the lagoons warm up.
Lagoon temperatures in the winter are in the order of 0°C to 5"C, and in the
summer they can exceed 20°C.
At the time of the site visit in September 1999, the lagoon system was
producing an emuent quality of BOD5 < 15 mgiL and TSS < 5 mgL. On
average, the lagoon emuent BODj/TSS concentrations are approximately
20120 mgL, with occasional pmit exceedences during high flows in the
spring. During high flow periods, the plant also regularly exceeds the
maximum allowable daily flow stipulated in the discharge permit.
There are also a number of reported operating problems with the plant. These
include the "freezing" of inlet control valves to the lagoons due to corrosion,
and odour generation during the late spring and early summer. The nearest
houses are approximately 100 m away korn the lagoons. Occasional odour
complaints are received, particularly during the spring breakup when the
lagoon temperature increases, anaerobic biological activity increases and rising
sludge is observed. The operators address the problem by pumping sludge
from the primary lagoon to the secondary lagoon over a 6 week period during
this time.
3.1.2 Preliminary Treatment
The existing screening room has three influent channels: two 600 mm wide
channels (one equipped with a 75 mm trash rack, one bypass) and a central 450