Municipal Class Environmental Assessment

Part C - Municipal Water and Wastewater Projects

C.2 DESCRIPTION OF THE PROJECTS, PURPOSE AND ALTERNATIVES

C.2.2 SANITARY SEWAGE PROJECTS

C.2.2 SANITARY SEWAGE PROJECTS

C.2.2.1 Description of the Projects

Projects planned under this Class EA can generally be categorized as: 

• new sanitary sewage systems
• expansions to existing sanitary sewage systems
• upgrading of existing sanitary sewage system.

 

A new sanitary sewage system may include a sanitary sewage collection system, flow equalization facilities, a treatment plant, biosolids management facilities and effluent outfall/discharge/disposal facilities, and storage facilities.

Expansion to an existing sanitary sewage system refers to the addition of new equipment or facilities or through improvements to operations and maintenance activities to increase system capacity. 

Upgrading of an existing sanitary sewage system consists of additions or replacements to existing equipment or facilities or changes in management practices which are intended to achieve a higher level or improved quality of system performance, while not increasing system capacity. 

Sanitary Sewage System Components: 

A typical sanitary sewage system may commonly include all or some of the following components: 

• collection
• treatment
• effluent disposal
• management of biosolids
• storage

 

The collection component of a sewage system collects raw sewage from a source and delivers it to the treatment component via one or more of the following: 

• gravity sewers
• vacuum lines
• pumping stations
• forcemains

 

The treatment component consists of one or more of the following facilities: 

• an individual septic tank and tile field (servicing one building)
• a communal septic tank(s) and tile field(s) (servicing a number of buildings)
• a lagoon or waste stabilization pond
• a sewage treatment plant (STP)
• effluent outfall (may include diffuser and/or mixing zone).

 

Each of the above treatment facilities uses different processes and also produces wastewater effluent and biosolids. 

The effluent disposal component consists of one or more of the following facilities or practices: 

• outfall sewer (to surface water body receiver)
• diffusers and/or mixing zone (in surface water body receiver)
• disposal on land by spray irrigation and/or snow effluent
• subsurface disposal tile field
• infiltration lagoon (to ground water body receiver)

 

The biosolids management component consists of one or more of the following facilities or practices:

• disposal of biosolids at a sanitary landfill site
• disposal of biosolids by burning it in an incinerator
• utilization of biosolids by applying it to soil conditioning sites (agricultural fields)
• utilization of biosolids by composting
• a biosolids transfer station to store biosolids on a temporary basis

The storage component consists of one or more of the following facilities: 

• flow equalization facility
• lagoon systems
• storage for combined sewage overflow.

 

An expansion or upgrading project may include the construction of one or more of the following facilities: 

• sewers (gravity sewer, vacuum line, forcemain)
• pumping stations
• communal septic tanks and/or tile fields
• sewage treatment plants
• lagoon systems
• facilities for the disposal or utilization of biosolids
• flow equalization facility
• storage (e.g. for combined sewage overflow)

 

The development and implementation of a project under this Class EA will often involve additional work and activities incidental to the primary purpose of the project but which must be included in the project. These may include, for example: 

• construction of new facilities or additions to existing facilities such as settling or aeration tanks, incinerators and buildings
• acquisition of additional land to house the facilities, either at existing sites or new locations
• extension and/or widening of existing sewer easement or utility corridor
• acquisition of additional land to maintain the appropriate “buffer zones” between adjacent uses and the treatment facilities

C.2.2.2 Purpose of the Project

Projects developed under this Class EA will be proposed to resolve problems affecting the operation and efficiency of existing systems, and/or to accommodate future growth of communities, or to alleviate specific pollution problems. 

One or more of the following general objectives will be achieved: 

a) Eliminate or reduce risk of public health problems or nuisances.
b) Improve the quality of effluent produced by the existing sewage system.
c) Improve the management of biosolids waste produced by the system.
d) Expand the capacity of the sewage system to solve existing problems or to accommodate future growth.
e) Improve system efficiency.
f) Prevent system failure.

The purpose or objective of a specific project will be determined by existing or anticipated problem(s) affecting the operation and deficiency of the system, and the present or forecast demand for increased system capacity. 

The following are descriptions of the types of problems and demands identified above: 

a) Public Health: 

The well-being of human life may be affected, or nuisances may be caused, by such problems as: 

• contamination of groundwater supply or surface water supply used for human consumption, livestock watering, recreation or irrigation
• failure of the system resulting in the backup of raw sewage through the sewers into basements
• failure to meet air quality requirements at biosolids incinerators
• odour from the sewage treatment facilities or from a biosolids transfer station
• noise from operation of a pumping station or sewage treatment plant
• traffic hazards, nuisance or noise from trucking of biosolids.
• bypassing of sanitary sewage flows at a treatment plant or pumping station during periods of high flow

 
b) Effluent Quality: 

The objectives for water quality include criteria governing the physical and inorganic characteristics of water bodies (e.g. temperature, dissolved oxygen, chlorine, phosphorous), microbiological criteria and the allowable concentration of all parameters that may cause an impact to receiving water quality.  The quality of the effluent produced by a sewage treatment plant must be adequate to ensure that the minimum standards set for the receiving water body or for land disposal can be consistently achieved. 

It is the responsibility of the proponent to assess, or to confirm, the assimilative capacity of the receiver, derive effluent quality criteria from this assessment (concentrations and loadings) and have them confirmed by the Ministry of the Environment. This shall be done in the earliest stages of the planning and design process and the results should serve as the basis for comparison of alternative solutions. 

The rationale for an expansion or upgrading project, based on the effluent quality criteria may be due to such problems as: 

• inefficient operation of the treatment facility
• outdated original design of the system
• original design criteria are no longer acceptable
• industrial waste discharged contains chemicals toxic to the biological treatment process used in the treatment facility
• changes in policies and guidelines for sewage treatment processes and for the receiving water body
• changes in the physical and chemical characteristics of the influent due to sewer discharges and/or infiltration/inflow into the sewer system
• assimilative capacity of the receiving water body.

 
c) Management of Biosolids: 

The need for the project may result from problems such as: 

• the sanitary landfill site(s) at which biosolids are currently being disposed of may be at or near capacity
• the agricultural lands or soil conditioning sites at which biosolids are utilized may be at or near capacity
• the constituents of the biosolids may make them unacceptable for disposal/utilization at existing available sites
• Ministry policies or guidelines for biosolids disposal/utilization may have changed
• changes in agricultural practices making land unavailable for spreading biosolids
• cost of haulage of biosolids to a distant landfill site may be prohibitive
• biosolids incinerator may be at or near capacity.

 
d) System Capacity: 

The existing sewage system may not be capable of handling present or forecast volumes of sewage due to such problems as: 

• system is at or approaching its original design capacity and cannot accommodate increased volumes of sewage
• outdated original design or construction of the system
• deterioration in the condition of the collection system
• infiltration of groundwater into the collection system
• illegal connections into the collection system
• changes in design philosophy.

 
e) System Efficiency: 

Various facets of system efficiency such as labour, maintenance costs or energy consumption may be improved by design improvements and/or the introduction of new technology, by plant optimization, process audit and real time control. 

f) Potential System Failure: 

Concern may be expressed as to potential system failure due to such factors as: 

• deterioration of system components due to age
• structural failure of system components
• deterioration due to chemical attack
• repeated equipment breakdown
• outdated original design and/or construction of the system

C.2.2.3 Alternative Solutions

There may be a number of ways of solving problems, of meeting new demands on existing sewage systems. A number of solutions, termed “Alternative Solutions”, may include, for example:

a) New sanitary sewage system
b) Expansion or upgrading of existing sanitary sewage system
c) Rehabilitate existing sanitary sewage system
d) Modify operational practices at the treatment facility
e) Expand maintenance program
f) Improve individual septic systems
g) Reduce sewage flows
h) Reduce industrial discharge
i) Improve combined sewer system control
j) Alter current biosolids management practices
k) Limit community growth
l) Discharge to an adjacent existing sewage system
m) Construct a new sewage/lagoon treatment facility
n) “Do Nothing” 

In evaluating Alternative Solutions the following factors should be kept in mind: 

• A sewage system consists of a series of inter-related components.  Therefore, many of the potential alternative solutions may resolve more than one of the general problems previously described.
• The feasibility of the alternative solutions will depend, in part, on the nature and location of the sewage system, the nature and location of the problem(s), the assimilative capacity of the receiver, the comparative cost of the alternative solutions, the pressures for growth and the municipality's capacity to finance the extension of services.

 

For the alternative solutions identified above, a number of possible options are suggested: 

a) New Sanitary Sewage System: 

• limit growth
• expand existing sanitary sewage system
• use individual septic tanks for each property

 
b) Expansion or Upgrading of Existing System: 

• limit growth
• improve operation and maintenance of existing system
• establish new sanitary sewage system
• management of peak flows by providing on-line storage

c) Rehabilitate Existing Sanitary Sewage System: 

• reline and/or seal existing sewers
• reconstruct existing sewers
• improve operation and maintenance of existing system
• modify drainage area
• management of peak flows by providing on-line storage

 
d) Modify Operational Practices at the Treatment Facility: 

• limit operating hours of noisy equipment to reduce sound levels
• reschedule the timing for, or haulage routes of, trucks removing biosolids from the treatment facility to minimize traffic and safety problems in residential areas
• alter quantities of biosolids stored at the treatment facility and/or duration of biosolids storage to minimize odour problems
• alter timing or duration of land treatment
• audit process and optimize operational efficiency
• undertake training programs to upgrade operator's understanding of treatment procedures and Ministry policies, guidelines and practices
• real time control of treatment processes

 
e) Expand Maintenance Program: 

• clean the sewage system to improve treatment efficiency and hydraulic characteristics
• undertake maintenance activities such as equipment overhaul, replacement of parts, repair of damaged tanks

 
f) Improve Individual Septic Systems: 

• repair, clean and enlarge existing septic tanks and/or tile fields.

 
g) Reduce Sewage Flows: 

• enforce municipal by-laws with respect to permitted connections to the sewage collection system e.g. sever illegal roof drains and weeping tiles
• maintain the collection system to minimize groundwater infiltration and stormwater in-flow into the sewers
• initiate a community water conservation program in order to reduce overall sewage volumes.

 
h) Reduce Industrial Discharge: 

• adopt a sewer use by-law in the municipality to set criteria for the quality of industrial sewage discharge
• amend existing sewer use by-law in order to require pretreatment of sewage at industrial plants
• amend existing sewer use by-law in order to require process changes in industrial plants
• appoint an Industrial Waste Inspector and ensure that violations of the by-law are sought out and the by-law is vigorously enforced.

i) Improve Combined Sewer System Control: 

In situations where combined sewers exist, the following alternatives may be considered: 

• provide or expand temporary or permanent surface runoff storage facilities to accommodate “wet weather” peak surface run-off flows, e.g. in ponds, swales, fields, parking lots, roof tops, parks
• install inlet controls, as part of normal maintenance activities, to prevent surcharge of combined sewers during “wet weather” peak run-off periods
• improve street maintenance program (i.e. cleaning, removal and disposal of debris) to minimize grit and solids entering combined sewers
• improve sewer maintenance program (e.g. sewer flushing, catch basin cleaning) to minimize grit, solids and slime being by-passed by combined sewer overflows
• install stationary or automatic flow regulators to utilize available storage capacity in an existing system.

j) Alter Current Biosolids Management Practices: 

• utilize alternative chemicals or quantities of chemicals and/or chemical dosing methods to change characteristics of biosolids thereby making it acceptable for disposal utilization
• maintain or improve biosolids dewatering equipment to increase process efficiency and reduce biosolids volume.
• alter the application rate of biosolids disposal at existing landfill site(s)
• alter the application rate of biosolids utilized on existing agricultural land
• alter the quantity of biosolids stored on a contingency basis in existing facilities at the treatment plant or transfer stations, in order to resolve scheduling problems at disposal or utilization sites
• construct a new biosolids incinerator to complement/ substitute for existing disposal/utilization methods
• improve the operating efficiency of an existing biosolids incinerator.

k) Limit Community Growth: 

• limit the ultimate extent and/or location of proposed residential industrial and commercial growth in the community
• phase or schedule proposed growth in the community with respect to both location and implementation timing.

l) Discharge to an Adjacent Existing Sewage System: 

• discharge sewage from existing or proposed development into an existing sewage system located in an adjacent municipality.

 m) Construct A New Sewage/Lagoon Treatment Facility: 

 

• construct a new sewage treatment plant within an existing collection and treatment system to replace or supplement an existing sewage treatment plant or lagoon treatment facility
• construct a new lagoon treatment facility to supplement or replace an existing communal and/or subsurface disposal system.

n) “Do Nothing”: 

In the “Do Nothing” alternative, no improvements or changes would be made to solve the identified problem(s). This means that the problems would remain in the system. 

It does not necessarily mean however, that no further development in the community would occur. The “Do Nothing” alternative shall be documented in the ESR along with any other alternative solutions which were examined. 

The “Do Nothing” alternative may be implemented at any time during the design process prior to the commencement of construction. A decision to “Do Nothing” would typically be made when the costs of all other alternatives, both financial and environmental, significantly outweigh the benefits.