It is estimated that the Port Elgin sanitary sewage system is currently servicing an equivalent population of approximately 9,970 (4,189 EHU’s). There are 479 properties in the Port Elgin service area that are connected to municipal water, but not sewers. The majority of these are in the southwest part of the community.
A comparison of existing flows to WWTP capacity is as follows:
Average Annual Flow = 3,735 m3/d actual vs 6,455 m3/d capacity 5
Peak Flow Rate = 16,475 m3/d actual vs 18,720 m3/d capacity6
It is projected that the Port Elgin sanitary service area will increase from 4,189 EHU’s to
approximately 6,097 EHU’s by 2034. This assumes that the 479 currently unserviced properties will be serviced within the 20 year period.
Based on the projected growth, average annual sewage flows will increase to approximately 5,426 m3/d which is 84% of plant capacity. Peak sewage flows will increase to approximately 24,000 m3/d which exceeds the capacity of the existing disinfection system and outfall, but is within the theoretical capacity of the primary treatment components.
Analyses established that the existing aerobic digester is already theoretically undersized based on criteria in the MOE Guidelines (Ref 13). Any performance problems associated with this are off-set by the fact that digestion continues to occur in the sludge holding tank.
At this time we do not suggest expansion of the digester, although future modifications could be triggered by:
Deterioration of digester performance (e.g. odour issues)
Energy considerations related to the digestion and storage process
A need to expand biosolids storage should six months capacity become an operational problem
A change in the plant process triggered by a change in effluent quality criteria
5 Annual Average Capacity is a compliance criteria in the current ECA.
6 Peak Capacity is based on the UV system capacity. The limiting components are disinfection and the outfall sewer.
In our opinion, any modifications to the biosolids system should be preceded by an investigation of biosolids management alternatives that considers at least:
Long term disposal needs
Energy considerations
Potential regulatory changes
Similar issues at the Southampton WWTP 5.8.2 Risks
Other than the capacity of the UV disinfection system and the existing outfall sewer, there are no apparent capacity issues within the study period for the primary treatment components at the Port Elgin WWTP. Certain assumptions have been made regarding rates of development and where development will occur (e.g. 62% Port Elgin are and 38% Southampton area). There is sufficient reserve capacity that there will be ample opportunity to respond to growth that exceeds what is projected in this Master Plan.
Peak wastewater flows are not currently measured and recorded. Values used in this Master Plan are estimates based on available data. It is important to note that the real peak flow to the
WWTP is the sum of the discharges from the two large SPS’s, and there is the capability of exceeding the estimated value. Based on historical information, exceedances would be very infrequent. As the service area expands risk will increase, but it is currently low.
It has long been the practice of the MOE to change effluent quality requirements (i.e. make them more stringent) when a capacity increase is requested. It is possible that the MOE could lower the allowable concentrations for both BOD5 and TSS and add criteria for nitrogen parameters
(e.g. ammonia).
The first opportunity for the MOE to consider changes will be during the Class EA process for the UV system and outfall currently underway.
We recommend that biosolids quantities and storage requirements be monitored on at least a five year frequency. Should treatment or storage problems occur, then a formal biosolids
management study, including consideration of the Southampton WWTP, should be undertaken. Biosolids storage capacity is less than the eight months recommended by the MOE Guidelines. Should the Guideline values be enforced through regulation or other means, it will be necessary to determine how biosolids should be managed going forward.
A review of the impact of future development and the potential connection of areas currently without sanitary servicing (e.g. Gobels Grove) has established that the sections of existing sanitary sewer on Harbour Street between Izzard Avenue and the Harbour Street SPS will be within 7% of theoretical capacity at full development. Because flows could change, we recommend re-assessment on a 5 year frequency or as the rate of development dictates.
5.9 Suggested Projects and Capital Costs
The UV system at the Port Elgin WWTP will need to be re-rated or expanded by approximately 2018. The probable cost of a UV system expansion is between $200,000 and $300,000 (2014$). It is noted that any physical expansion of the WWTP will be required to complete screening for cultural heritage and archeological resources. Also any future extension of the sewage collection system will need to consider impacts to heritage and archeological resources, as well as
alternatives to locating utilities in the Highway 21 corridor.
Subject to the following considerations, this study has not identified the need for other capital projects related to the Port Elgin sanitary sewage system at this time.
Rates of growth and total development are approximately what has been estimated for this analysis.
Per unit flows remain similar to current values.
Biosolids can continue to be land disposed on a 6 month cycle.
Process biosolids characteristics (e.g. solids concentrations, SRT’s) remain similar. It is recommended that the performance of the biosolids system and quantities vs storage capacity be monitored on at least a five year basis.
6.0 SOUTHAMPTON AREA SEWAGE SYSTEM