In Ontario, sewage systems are approved either under the Ontario Water Resources Act (OWRA) or under the Environmental Protection Act (EPA). In general, a sewage system which discharges treated effluent to a surface water requires approval under Section 53 of the OWRA (formerly Section 24).
The Ministry of the Environment's (MOE's) legislative authority to manage the quality of Ontario's water resources is provided under the Act and includes specifying sewage treatment works effluent requirements which are typically presented in the form of a Certificate of Approval (a legal instrument).
The purpose of issuing a Certificate of Approval (C of A) for sewage treatment system is to ensure adequate protection of Ontario's surface waters. Effluent limits are incorporated into the Certificate of Approval to ensure minimal impact to the receiving stream.
The Petawawa WPCP is operated under C of A #1276-5YFSZH, issued on June 24, 2006. Conditions placed in this C of A address a number of issues associated with the operation and maintenance of the Petawawa WPCP and also specify effluent "requirements" and "objectives" along with sampling requirements. Table 1 presents a summary of the effluent requirements and objectives specified in the C of A.
Table 1: Certificate of Approval Effluent Requirements/Objectives
Parameter | Effluent Requirements | Effluent Objectives | ||
Concentration (mg/L) |
Total Loading (kg/day) |
Con-centration (mg/L0 |
Total Loading (kg/d) |
|
CBOD5 | 25.0 | 218 | 15.0 | 131 |
Suspended Solids | 25.0 | 218 | 15.0 | 131 |
Total Ammonia | 5.0 | 43.5 | <5.0 | <43.5 |
Total Phosphorous | 1.0 | 8.7 | 1 | 8.7 |
pH | 6.0-9.5 units | - | - | - |
Escherichia Coli (E.Coli) |
200 organisms/100mL |
The effluent "requirements" represent the concentrations which indicate noncompliance. The effluent "objectives"are intended as target concentrations which should be set as goals to be achieved under most operating conditions.
Noncompliance with the C of A occurs if:
Also set out in the C of A are the minimum requirements for determining effluent quality. These sampling requirements are presented in the next table.
Parameter |
Location |
Type of Sample | Min. Frequency |
CBOD5 | Raw/Final | Composite | Monthly |
SS | Raw/Final | Composite | Monthly |
Free Ammonia Nitrogen | Raw | Grab | Monthly |
Total Kjeldahl Nitrogen (TKN) | Raw | Composite | Monthly |
Total Ammonia | Final | Composite | 3 times/week |
Total P | Raw/Final | Composite | 3 times/week |
pH | Final | Grab | 3 times/week |
Alkalinity | Final | Composite | 3 times/week |
Temp. | Final | Grab | 3 times/week |