Conveyance and End-of-Pipe Measures for Stormwater - FCM

Table 4–1b: Application of End-of-Pipe Control Best Management Practices (continued)
Screening
Application
Requirements
Opportunities and
Limitations
Proven Effectiveness
4.5 Cost
Capital costs and operation and maintenance
costs for stormwater best management
practices are difficult to generalize as they are
highly variable and depend on site-specific
requirements, such as geographical location,
stormwater quality criteria, design objectives,
land uses and environmental considerations.
Also, costs vary as a function of the local
economies. The total cost of implementing a
stormwater best management practice
involves a number of components including
the costs associated with administration,
planning and design, land acquisition, site
preparation and development, and operation
and maintenance.
Capital costs are the total costs, including
labour and materials associated with the
actual on-site construction, of the facility.
The primary application is in conjunction with treatment/storage facilities to remove
the larger solids. However, screening can also be applied as a stand-alone device
to remove solids before discharge to receiving waters. Stand-alone devices need
to be housed in a chamber with disposal capabilities to remove the waste periodically.
Opportunity identified based on land availability upstream of a storage/treatment facility
or outfall structure, and impact on aquatic habitats and life.
Normal solids removal rate varies from 30% to 50%. However, screening devices
are susceptible to clogging.
Cost Capital cost: low. Operation and maintenance costs: high.
Oil/Grit Separators
Application
Requirements
Opportunities and
Limitations
Proven Effectiveness
Oil/grit separators are best applied in areas of high impervious cover where there
is a potential for hydrocarbon spills and polluted sediment discharges. They are also
used for pre-treatment of inflows to ponds/wetlands or as part of a treatment train.
Opportunity identified based on land availability, tributary area, and outfall location.
Effective for treatment of stormwater pollution at its source or at the inlet of
ponds/wetlands. Some may be effective in reducing coarse total suspended solids.
Cost Capital cost: low. Operation and maintenance costs: medium.
Operation and maintenance costs include the
total labour and the expenses associated with
operating, monitoring, and maintaining the
best management practice at an acceptable
level of performance. Appropriate operation
and maintenance budgets are an essential
component of all stormwater best
management practices.
Where cost information is provided,
references are cited. Such information should
be used cautiously during the planning stage.
Costs however are given, in a comparative
basis as high, medium, and low. Operating
costs should also include provisions for
ongoing performance monitoring of the best
management practice to optimize operation
and maintenance requirements and determine
the effectiveness of the best management
practice in enhancing hydrologic and water
quality conditions. Information on maintenance
costs is given in Ontario, MOE, (2003), AEP
(1999), Jaska (2000), and Barr Engineering
(2001).
Conveyance and End-of-Pipe Measures for Stormwater Control — July 2005 41
4. Applications and
Limitations
4.4 Management
Practices
4.5 Cost
Table 4–1b
Application of End-of-Pipe
Control Best Management
Practices (continued)
The total cost
of implementing
a stormwater best
management
practice involves
a number
of components
including the costs
associated with
administration,
planning and
design, land
acquisition,
site preparation
and development,
and operation
and maintenance.