Blackburn Wastewater Treatment Plant Upgrade Study

Section 2.0 - III Mitigation Measures
The I/I control program should incorporate ongoing performance monitoring by
collecting additional performance data to monitor the cost effectiveness of the
various rehabilitation techniques.
It is important to control both the "on-lot" UI and "on-street" I/I by developing a
public information/participation component into the IT management strategy. Control
of "on lot" V1 has significant merit as it is a 'source control' at the top end which
eliminates entry into the sewer network. However, it can be hught with the often
challenging need to get the homeowner's buy-in. This would need a review of the
service connection and lot grading practiceshy-laws applicable to existing lots as well
as future developments.
The City commissioned Stantec Consulting Ltd. to complete a study on Vl in the
Blackburn sewage collection area Ad present conclusions and recommendations. The
final report was submitted June, 1999. Attached as Appendix A are the conclusions of
this report. In short, the Stantec Consulting report recommended that the most cost
effective approach to the VI problem was to implement a rehabilitation program for
manholes and the collection pipework.
Based on the Stantec Consulting report recommendations, the City plans to implement
during the operating year of 1999 a manhole rehabilitation program and attempt to
reduce by the end of 2000, PWWF by nearly 50 percent. Over the following 5 to 10
years, the VI reduction program would be ongoing.
2.2 IA REDUCTION PLAN
2.2.1 Inflow Reduction
The manhole rehabilitation work, set out by Stantec Consulting Ltd., has been
predicted to reduce the volume of inflow by 2,170 m3/d. Tnis brings the peak wet
weather flow (PWWF) down from 4,500 m3/d to 2,330 m3/d. However, this still
exceeds the limits of the discharge permit. Tberefore, Wher reduction of Ill is
required to meet design and permit requirements.
2.2.2 Infiltration Reduction
Population
Currently, the population for the Blackbum sewerage area is estimated to be 1,800. A
population growth rate of approximately 4.2 percent is assumed for the area and based
on this growth rate the population in 25 years will be 5,000. See Table 2.1.