The document discusses considerations for using water quality offsets to help sewage treatment plants meet effluent discharge requirements for substances like total phosphorus. It outlines two mechanisms Ontario allows for offsets - site-specific arrangements and a potential trading program. Key criteria the Ministry may require are demonstrating offsets are a last resort, having monitoring agreements, contingency plans if offsets underperform, and consultation during project planning. The article provides an overview of evaluation criteria still under development to help practitioners explore offset options.

1. A
t the September 24, 2014 meet-
ing of the Wastewater Practitio-
ners Group, members discussed
the topic of total phosphorus offsets in
sewage treatment plants. This discus-
sion was preceded by a great overview
provided by Mike Walters of the Lake
Simcoe Conservation Authority (LSCA)
about the Lake Simcoe Phosphorus
Offset Program (LSPOP). Apparent
from the discussion was the need for
better understanding of the offsetting
mechanisms used for sewage treatment
plant (STP) compliance and, essentially,
for better guidelines to approach these
offsetting tools. My preliminary scan of
historic approvals issued by the Ministry
of the Environment and Climate Change
(Ministry) with water quality offsetting
components accounted for eight munici-
pal and industrial STPs, but at the time
of writing this article I was made aware
of two more. Table 1 shows the prelimi-
nary list of sites currently approved with
offsetting tools.
Since the passing of the Lake Simcoe
Protection Act (LSPA) in 2008, its Plan
in 2009, and its Phosphorus Reduction
Strategy in 2010, water quality offset-
ting is now on the radar of both process
wastewater and stormwater manage-
ment practitioners. The objective of this
article is to provide an update to the
regulated community about preliminary
evaluation criteria under development
by the Environmental Approvals Branch
(EAB) when considering a proponent’s
request to have water quality offsetting
as a mechanism to comply with sewage
treatment plants (STP) effluent discharge
requirements, e.g., Total Phosphorus
(TP) offsets.
The Ministry has two mechanisms to
allow for water quality offsetting:
1. The one-offs, which go back to the
mid-1990s, are based on site-specific
conditions for municipal and/or
industrial STPs. The one-offs are
proponent-driven, and are deter-
mined on a case-by-case basis. The
Ministry can consider contaminant
offsets under the authority of the
Environmental Protection Act (EPA)
and Ontario Water Resources Act
(OWRA).
2. Under the LSPA, the Ministry
identified a potential phosphorus
trading mechanism. This mechanism
is referenced in the LSPA and in its
Lake Simcoe Protection Plan, under
policy 4.25 SA as the Water Quality
Trading Program. Under this Trading
Program, owners of STPs within the
Lake Simcoe basin could plan for
alternative removal options for more
effectively achieving TP mandated
requirements. While significant
research and work has been done to
date, this trading mechanism is still
to be defined. (Note: such program
would require development of a
regulation in accordance with sub-
sections 75(1.7-1.10) of the OWRA).
The science, feasibility and scope of
any proposed site-specific water quality
offsetting project is the responsibility of
the Ministry Regional Office Technical
Support Section (RTSS). Traditionally,
it is at the planning phase when water
quality offsetting components such as
the review and acceptance of identified
offset methods, proposed locations for
offset projects, estimation of credits for
given offset measures, applicable offset
ratios for specific stormwater manage-
ment (SWM) measures, implementation
schedule for specific measures, etc are
determined. Proponents should seek
advice from RTSS to understand those
considerations.
Proponents, either municipal or
industrial, can explore water quality
offsets as part of their sewage treatment
plant designs. For the municipal sector,
consideration of water quality offsetting
occurs under the framework of the plan-
ning process and applicable environ-
mental assessment (EA) requirements.
It is at this stage when Ministry staff
from the RTSS and the Environmental
Assessment section would have the
opportunity to comment and provide
guidance in terms of regulatory and
environmental feasibility. At this stage,
it is also recommended to seek com-
ments from the EAB for technical and
approval requirements and site specific
recommendations.
For the industrial sector, while plan-
ning decisions are generally exempt
from EA requirements, proponents must
complete an evaluation of alternatives
that demonstrate proper consideration
to scientific, environmental and compli-
ance considerations.
The following list of water quality
offset considerations is preliminary and
is not intended to show the Ministry’s
actual requirements. These consider-
ations apply to both municipal and
industrial projects.
(a) STP effluent discharge criteria.
Proponents have to follow the
standard approach for determin-
ing effluent requirements, i.e.,
completing an assimilative capacity
assessment for each contaminant
of concern and having proposed
effluent limits and objectives.
Such discharge criteria should be
confirmed by the Ministry’s RTSS
at the time of Class EA (municipal)
or at pre-submission consultation
(industrial). Similarly, as with any
other application, it is EAB’s expec-
tation to have final effluent criteria
(objectives and limits) confirmed by
our RTSS at the time of submission
of the application package.
(b)Offsetting mechanism as a measure
of last resort. The water qual-
ity offsetting is generally seen as
a measure of last resort and after
careful evaluation has been given to
on-site solutions. EAB can consider
water quality offsetting arrangements
involving offsite areas if determined
as such in the context of:
• Class EA process for municipal
systems, or
Environmental Approvals Branch’s Considerations
When Evaluating Water Quality Offsets
for New or Re-Rating of Municipal or
Industrial Sewage Treatment Plants
By Edgar Tovilla, P.Eng., Ministry of the Environment and Climate Change
64 Spring 2015INFLUENTS

2. • Results of alternative analysis for
industrial systems not subject to
Class EAs.
(c) Offset agreements. Proponents need
to consider within their overall water
quality offsetting plan a monitoring
and performance evaluation on a
continual basis. The use of a third
party to implement such monitor-
ing and evaluation plans may offer
benefits and accountability to dem-
onstrate the successful implementa-
tion of the project. For municipal
or industrial projects, a third party
could include a conservation author-
ity or an engineering consultant.
(d) Depending on the scope and ele-
ments of the offsetting proposal,
requirements may also involve
specific agreements between the
proponent (owner of the STP) and
the owner(s) of the sites where
proposed offset measures are to
be implemented. This will help to
ensure accountability on the part of
the proponent for meeting program
targets and any site-specific require-
ments. These agreements will specify
terms and conditions between
the STP owner and the respec-
tive owners of the offset measures,
covering such issues as costs, O&M
requirements, inspection, and com-
pliance monitoring and reporting.
(e) Operational monitoring and per-
formance compliance. Proponents
need to consider the preparation of a
Performance Assessment Report pref-
erably prepared by a third party who
is a licensed professional engineer in
the Province of Ontario and address-
ing the following:
• Performance evaluation of the
implemented offset measures,
including measurements/calcula-
tions of average loadings removed.
• Verification of loading reductions
achieved in comparison to
loading reduction targets (i.e.,
offset program goals).
• Description of any operating
problems or performance
limitations encountered and
corrective actions taken during
the reporting period and the need
for further investigations in the
following reporting period for
system refinements or ways of
improving its performance.
The plan on how to demonstrate
that the proposed offset project
(and the offset technologies to
be used) can achieve contami-
nant removal loadings/ratios
consistently should be part of
the planning phase, i.e., Class
EA. Taking such a plan to a
detailed design is a requirement
to be included in the application
for Environmental Compliance
Approval (ECA) and it should
be reviewed to the satisfaction
of EAB prior to approving the
proposal under an ECA.
(d) Contingency plan. Proponents may
be required to prepare and submit
a contingency plan for the event
that the monitoring and evaluation
of the system reveals that the
offsets are not performing and not
complying with the contaminant
loading reduction targets.
The EAB will continue to work with
practitioners in order to finalize the
above considerations and prepare
guidelines to assist wastewater
practitioners when exploring
offsetting mechanisms for municipal
or industrial sewage treatment plants.
Any comments are welcome:
please send them to the author at
edgar.tovilla@ontario.ca.
OWNER SITE’S NAME
1 Village of Casselman Casselman Lagoons
2 Township of North Dundas Winchester Sewage System
3 Municipality of The Nation Central Landfill
4 Laflèche Environmental Inc. Eastern Ontario Waste Handling Facility
5 Laflèche Leblanc Soil Recycling Inc. Lafleche LeBlanc Soil Recycling Inc.
6 Township of Russell Russell Sewage Lagoon
7 GFL Environmental Inc. GFL Environmental Inc – Moose Creek
8 Town of New Tecumseth Tottenham STP
Table 1 – Preliminary list of STPs with water quality offsetting arrangements to date.
www.xcg.com
• Toronto
• Kitchener
• Kingston
• Edmonton
• Halifax
• Cincinnati
XCG Consultants proudly celebrates
25 years of providing innovative and
practical environmental solutions in:
• Municipal Infrastructure
• Wastewater & Water Treatment
• Site Assessment & Remediation
• Water Resources
• Solid Waste Management
• Haz. Materials Management
• Training &
Operations
Visit us at www.xcg.com
65Spring 2015INFLUENTS