Report to/Rapport au:
Comité de l'urbanisme et de l'aménagement
and Council / et au Conseil
Submitted by/Soumis par: R.G. Hewitt
Acting Deputy City Manager / Directeur municipal adjoint
intérimaire,
Public Works and Services / Services et
travaux publics
Contact Person/Personne ressource: Kenneth J. Brothers, Director
Utility Services / Services publics
(613) 580-2424 x 22609, Ken.Brothers@ottawa.ca
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SUBJECT: |
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OBJET : |
RÉPONSE À IN-SINK-ERATOR
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That Planning
and Environment Committee deny the In-Sink-Erator (Canada) request to amend the
Sewer Use By-law to allow the use of food waste disposers in the City of
Ottawa.
RECOMMANDATION DU RAPPORT
Que le
Comité de l’urbanisme et de l’environnement rejette la demande de
In-Sink-Erator (Canada) concernant la modification du Règlement sur les égouts
visant à permettre l’utilisation de broyeurs de déchets dans la Ville d’Ottawa.
BACKGROUND
The City of Ottawa Sewer Use By-law, which was passed by Council in October 2003, prohibits the installation or operation of any type of garbage grinding device that discharges food waste directly or indirectly into the sewage works. At the Planning and Environment Committee (PEC) meeting of 24 November 2004, Chair Hume brought forward a report recommending that a presentation regarding the use of food waste disposers be received from In-Sink-Erator, a manufacturer of garbage grinding devices. The item was brought forward to the 14 December 2004 PEC meeting, where In-Sink-Erator made a presentation to Committee, requesting that the Sewer Use By-law be amended to allow the use of food waste disposers.
Staff were subsequently directed to review the presentation and present a report to Committee in the first quarter of 2005 containing: a review of the merits of the In-Sink-Erator request, substantiation of the current by-law position, the experience in other municipalities in Canada with respect to this issue, and the environmental impact of the requested amendment.
DISCUSSION
Staff have
reviewed the information provided by In-Sink-Erator, and do not concur that
many of the purported benefits of food waste disposal units would be realized
in the City of Ottawa. It is agreed
that their use may be beneficial in areas experiencing vermin problems from
improperly stored garbage, or where solid waste must be trucked over great
distances to a landfill site. These
circumstances do not exist in Ottawa.
There are four landfill sites in nearby proximity nor is the City and the City is not
experiencing vermin problems. Staff in
Solid Waste have also indicated that food waste is beneficial to the landfill
as it contributes to decomposition, assisting in the production of higher methane content landfill gas which
will in turn be converted into increased electrical power production from their
soon to be built electrical generation station. Food waste also assists in the biological treatment of leachate.
It is recognized that the rendering of food waste to compost or soil conditioners is of benefit to the environment. It is staff’s position that this benefit is better obtained through encouraging the composting efforts currently underway across the City rather than through subjecting food waste to costly and unnecessary processing at the wastewater treatment plant and the composting of the resulting biosolids. In addition, the potential for increases in sewer blockages, sewer lateral and mains maintenance, and wastewater treatment plant operating costs, reinforces the disadvantages of using these units in the City of Ottawa. Any advantages associated with the units are outweighed by the negative impacts on the City’s wastewater maintenance and operating costs.
The discharge of organics into the sanitary sewer system is in contradiction to the Integrated Waste Management Master Plan policy approved for solid waste diversion.
Committee and
Council approved the Solid Waste – Integrated Waste Management Master Plan –
Phase 2 Design Options (Report ACS2003-TUP-UTL-0019), which included among
other things the following recommendations:
“A further expansion of the waste diversion program to achieve waste diversion up 50 percent during the term of the next collection contract as outlined in this report (as option F3), including the following components:
a) Compost + residential service (food waste, leaf and yard waste); and …”
Staff are currently preparing a revised Integrated Waste Management Master Plan Strategy which includes household organics separation as an integral part of the waste diversion strategy to achieve greater than 40 percent diversion by 2006. The program clearly contemplates that Ottawa will be moving towards source separation of organics as a cornerstone of this policy with a net result of collecting household organic material for processing and/or composting as the preferred method of addressing waste diversion from the landfill. The notion of introducing household organics into the sewage collection system, and the corresponding pumping, wastewater treatment, and biosolid digestion process is contrary to the policy direction.
Household organics should be managed through the Integrated Waste Management Master Plan initiative that will be recommending that household organics be separated at the source, and composted or processed through the waste diversion initiative to a sustainable by-product of this program that will have beneficial use for land application, compost material or other environmentally sustainable products.
Prior to the revision of the Sewer Use By-law in 2003, the former City of Ottawa, and Townships of West Carleton and Goulbourn banned the installation of garbage grinding devices. These devices were not specifically addressed in the by-laws of most other local municipalities, where their use was permitted, by default. The issue was one of many harmonized in the Sewer Use By-law revision.
During the
By-law review process,
comments were received from Infrastructure Services and Wastewater and Drainage
staff requesting a complete ban on garbage grinders. Concerns were raised regarding the potential for the introduction
of increased fats and solids to the sewers and associated increases in sewer
blockages and maintenance requirements.
The potential for increased organic solids loadings, biosolids
production and treatment costs at the Pickard Centre were also identified. It was also indicated that permitting the
use of these devices, which are admittedly very convenient, would discourage
backyard composting and potentially interfereconflict with the City’s
(pilot) organics composting program and direction to pursue organics separation in
solid waste collection.
Further research into the matter indicated that there was a basis for these concerns. A fact sheet published by the United States Environmental Protection Agency indicated that the use of garbage grinders increases septic tank loadings of suspended solids by 40 to 90 percent and fats; oils and grease by 70 to 150 percent. Septic tanks to which garbage grinding devices are attached are usually sized at least twenty percent larger than others to accommodate the increased solids loading. There was no reason to believe that the impact on sewage discharged to a sewer would be any different, and a literature review supported the fact that the discharge of food waste to the sewer resulted in an increase in organic loading to the wastewater treatment plant. This increased loading would be translated into the production of additional biosolids at the Pickard Centre, and place additional loading on the digester facility.
During the time period where the by-law
review took place, Council banned the land application of biosolids, and the
more costly processes of composting and landfilling were undertaken. Concerns were raised that the kitchen waste
disposed of through food waste disposersgrinders would ultimately end up at the
landfill site or composted as biosolids, after undergoing a costly and
unnecessary treatment process.
Ultimately, it was decided that it would be best for the City to deal
with solid waste at the landfill site or through composting, rather than adding
it to the biosolids disposal issue.
This also served to minimize the potential for costly sewer blockages.
Regulations concerning the use of food waste disposers vary amongst municipalities, and are likely dependent on resources and the options available for dealing with solid waste, wastewater, and biosolids. In addition to Ottawa, the Cities of Kingston, Peterborough, Cobourg, and St. Thomas also have a complete ban on food waste disposal units. Cities like Toronto, Edmonton, and the Capital Regional District - Victoria have partial bans, for combined sewer areas and/or industrial use.
Many other
municipalities may not have a direct ban onthese grinder units, but as well, do not encourage
their use. This may be through
requiring a discharger to meet Sewer Use By-law limits for suspended solids,
such as in Durham and Hamilton, or through Best Management Practices: e.g., Vancouver discourages the “convenience
of garburators” in their Choices for Wiser Living newsletter because
“ground-up food clogs and contributes to the corrosion of the sewer.”
Due to long term use and lack of information, it is difficult to assess the impact of food waste disposers in other Canadian municipalities. Most municipalities experience sewer blockages and grease problems. It is not possible to assess to what extent food waste disposers may contribute to these issues. Other variables could include the age and design of sewers, the environmental awareness of a community, and the penetration rate of the disposal units.
According to literature provided by In-Sink-Erator, the City of Los Angeles mandated the installation of food waste disposers in new and renovated residential, commercial and institutional kitchens. Several years ago, Los Angeles hired forty people solely to implement a Fats Oil & Grease Control Program, to prevent the introduction of grease to the sewers. Food service establishments are now required to adhere to Best Management Practices, which include a prohibition on the installation of garbage grinders in new facilities. Except where expressly allowed by the Bureau of Sanitation, garbage grinders in existing facilities must be removed. It is also our understanding that the City of Los Angeles Integrated Resources Plan Steering group has flagged the investigation of limiting or eliminating the use of garbage disposals in residences as an option to alleviate some of the loading in the wastewater treatment plants and the sewer system.
A ban on food waste disposers in New York City was lifted in 1997. The original imposition of the ban coincided with the closure of the only landfill site within their City limits and a significant vermin problem. The results of the analyses conducted at the lifting of the ban raised a cautionary flag at high market penetration rates. As a result, the Department of Environmental Protection tracks their installation and continues to monitor their impact.
A life-cycle inventory, used to compare different systems for managing food waste, was published in the Journal of Waste Management and Research in December 2003. It quantified total materials, energy, costs and environmental flows for each system. The information appears to have been obtained from a study performed at the University of Wisconsin, and In-Sink-Erator has published a brief summary and their interpretation of the data and conclusions on their web site.
In terms of the environmental life-cycle costs, municipal waste disposal followed by composting ranked first, requiring the least material and water inputs, and generating the least wastewater and waterborne waste.
Since the convenience of food waste disposers could easily discourage composting efforts, a continued ban on these devices would appear to have the least environmental impact. Lifting the ban could result in the production of additional water borne wastes and biosolids, along with the potential for blocked sanitary sewer mains, service laterals, and overflows.
The merits of the In-Sink-Erator request have been considered, and are summarized in Appendix A. Staff have also reviewed the studies provided by In-Sink-Erator. Generally speaking, it was found that the information provided in the studies did not necessarily support the claims regarding the use of food waste disposers, nor did it serve to alleviate the concerns that initially led to the prohibition on these units. Whatever waste goes down the drain through one of these devices creates an additional burden on the sewage works that could be avoided through composting or even land filling.
Most studies confirmed that the use of food waste disposers results in an increase in the loading of solids and grease to the sewers, along with associated increases in oxygen requirements and sludge production. The significance of the increases would vary, dependent on the market penetration rate of food waste disposers. It was also indicated that these increases were quite different, depending on the study cited. Two studies were of a “relatively brief duration”, one of which indicated their conclusions were uncertain and recommended a much longer investigation period and process specific experimental program for meaningful results.
Staff were also concerned that the significance of some issues or impacts may have been understated. For example, although studies have shown that wastewater solids loading increases by 20% per person, and the production of biosolids may increase by five to nine percent at a penetration rate of 10%, In-Sink-Erator claims that the use of food waste disposers does not significantly increase the load on the sewage treatment plant. Significance is dependant on population, penetration rate, conditions in the sewers and capacity at the wastewater treatment plant. All of these factors are subject to change. It is for that reason, that staff have been precautionary in their approach to the use of food waste disposers, and maintained the ban implemented by the former City of Ottawa.
Processing costs provided by In-Sink-Erator that lifting the ban on food waste disposers would be, at worst, revenue neutral, were found to be incorrect. Staff has concluded that the cost to process one tonne of food waste at the Pickard Centre is $165.00. The cost to have the same waste transported to and disposed of at the landfill site is $88.00. In addition, the claims by In-Sink-Erator regarding the value of additional biogas production do not apply to the situation in the City of Ottawa. The gas may be produced; however, it does not offset increased processing costs and it cannot be used without a significant capital investment with a long pay back period.
Claims regarding
the “de minimis” impact of food waste disposers on sewers and sewer maintenance
were difficult to substantiate. One
study indicated that 16.8 percent total solids weight might have settled in the
sewer, but no problems with solids settling in the sewer were noted. Others stated that maintenance costs could
increase, but the amount was dependent on the penetration rate. This is of concern to staff due to the impact
on resources for sewer maintenance.
There are currently 62,000 metres of sewer that require quarterly
maintenance as a result of grease and solids build up and another 60 locations
being investigated. The City also has
numerous areas of flat or sagging sewers where sediment settling and blockages
could becomean issue more acute with additional solids and fat loading
from grinder use.
It costs the City almost twice as much to process food waste at the Pickard Centre, than to have it transported to the landfill site. From a waste management point of view, there is currently no need for the use of food waste disposers in Ottawa. From environmental and operational perspectives, the long-term disadvantages of food waste disposers outweigh the advantages, in the City of Ottawa. Staff maintain that the prohibition on the use of food waste disposers in the City of Ottawa remains both fiscally and environmentally responsible.
ENVIRONMENTAL IMPLICATIONS
Lifting the ban on garbage grinding devices in the City of Ottawa could result in the production of additional water borne wastes and biosolids, along with the potential for blocked sewers and overflows.
RURAL
IMPLICATIONS
There are no rural implications to this report. However, the use of grinders in septic systems would likely increase the loading and septic tank cleaning cycles.
CONSULTATION
There have
been ongoing discussions between In-Sink-Erator and City of Ottawa staff. A presentation was also given to the
Environmental Advisory Committee on 10 February 2005. They unanimously endorsed staff’s position and recommended: “That the Environmental Advisory Committee support the City staff
requirement to maintain the ban on food waste disposers.”
FINANCIAL IMPLICATIONS
There are no financial
implications to this report. Lifting
the ban on garbage grinding devices in the City of Ottawa could result in
increased sewer maintenance and wastewater treatment costs over time.
This would result in an increase in the sewer surcharge.
SUPPORTING DOCUMENTATION
Appendix A – Summary of the Merits of In-Sink-Erator
DISPOSITION
Staff will continue to enforce a ban on In-Sink-Erator as per the Sewer Use By-law.
In-Sink-Erator Claim
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Staff Response |
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Convenient and hygienic method of food
residual disposal |
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Agree,
however, this may make composting (the most environmentally beneficial method
of disposal) unattractive. |
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Do not cause sewer blockages |
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Studies
indicate use of disposers would result in a 20% increase in solids and
grease, per capita. ·
Ottawa has
numerous areas of flat or sagging sewers where settling and blockages could
become an issue. |
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Do not significantly increase water usage |
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Studies
show increased water use of 3-4.5 L/per day per capita. Significance related to how widespread use
becomes. |
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Do not significantly increase the load on
the sewage treatment plant |
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Whatever
goes down the drain through one of these devices creates an additional burden
on the wastewater treatment plant that could be avoided through composting. ·
A
University of Lund study showed a 50% increase in the loading of organic
matter, resulting in an increase of sludge.
Several other studies corroborate increased loadings and sludge
production. |
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Can not be used in combined sewers |
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Potential
for overflow to Ottawa River makes increasing the organic strength of the
sewage in these areas environmentally irresponsible. |
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New York City Study resulted in lifting
of ban on food waste disposers in 1997 |
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The lifting
of the ban on food waste disposers in New York City coincided with the
closure of their only landfill site and a vermin problem. Neither of these issues are a factor in
Ottawa. |
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Since food waste is 70% water and mostly
organic, sewage treatment plant is the natural processing facility for food
waste |
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The most
natural processing for food waste is composting. ·
Food waste
that is not 70% water (e.g. bones, eggshells) can produce up to triple their
weight in biosolids. ·
The
additional nitrogen content of food waste could result in a requirement for
the wastewater treatment plant to add unit processes for nitrogen removal. |
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Addition of food waste to wastewater
treatment plant enhances nutrient removal |
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Disagree. Does not apply to the operation in the
City of Ottawa. |
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Removing food waste water from the
landfill reduces leachate volume and improves its quality |
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Typical
municipal waste is ~ 16% moisture. ·
Leachate is
produced only from rainfall and snow melt, not food waste. ·
Food waste
does not contribute negatively to the quality of leachate; removing it from
the landfill site could concentrate undesirable components, making it more
difficult to treat. ·
Food waste
is beneficial to the landfill as it contributes to decomposition, assisting
production of higher methane gas which is soon to be converted into
electrical power production from the generation station currently under
construction. ·
Increased
BOD provided by food waste enhances the biological treatment of leachate. |
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Effects of food waste disposers are
minimal at the wastewater treatment plant |
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Significance
is dependent on use, but review of studies indicates potential for additional
costs in the millions of dollars. May
be minimal in relation to entire budget, but could be avoided through
composting. |
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Capture and beneficial use of energy
produced by methane generated in digested food waste solids |
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Increased
gas production does not offset increased processing cost. ·
Pickard
Centre has limited ability to utilize additional gas without a significant
capital investment with a long pay back period. ·
Trail Road
is currently building an electrical generation station to reuse methane
produced at the landfill site. |
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Most sewer overflows due to trash and
tree roots, not grease blockages |
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Disagree,
based on experience in City of Ottawa. |
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Regular maintenance and cleaning controls
grease blockages |
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There are
currently 62,000 metres of sewer that require quarterly maintenance as a
result of grease and solids build-up and another 60 locations being
investigated. |
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Ottawa is unique in its total ban on food
waste disposers |
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Peterborough,
Kingston and Cobourg have a ban in place. ·
Many other
municipalities do not condone their use, e.g. Vancouver discourages the
“convenience of garburators” in their Choices for Wiser Living newsletter
because “ground-up food clogs and contributes to the corrosion of the sewer
pipes.” |
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Cost to process food waste at the
wastewater treatment plant is much lower than the solid waste processing
costs |
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Cost of
processing waste at the Pickard Centre is $165.00/ton. ·
Cost of
solid waste disposal is $88.00/ton. |
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Independent Study – New York City |
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Study
clearly states the units may cause increases in solids and oil and grease in
the sewer system. (Literature value
of 20% per capita) that might result in increased maintenance costs. ·
Sewer
maintenance cost estimated to increase by 7.6% at penetration rate of 38%. ·
Study was
of “relatively brief duration” making results of sewer videotaping
inconclusive. ·
States
additional food waste loadings could incur additional capital and operating
costs for increased aeration and sludge treatment requirements. |
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Independent Study Data – The under Sink
Garbage Grinder |
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States that
a number of studies have reported an increase in the loading of solids,
grease and oils in the sewer and an increase in oxygen requirement and sludge
production. ·
Activated
sludge concentration, oxygen consumption and biosolids production increased
significantly. ·
Results
revealed that only 18.8% total solids weight settled in the
sewer. (Pasta and bread had 20%
settling rate in sewers; meat, fish and vegetables averaged 8%). |
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Independent Study Data – Technical |
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Study was
“by order of In-Sink-Erator”, therefore doesn’t appear to be independent. ·
Cites 9%
increase in sludge production with 10% penetration rate. |
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Independent Study Data – Surahammar,
Sweden |
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States that
conclusions are very uncertain.
Recommends much longer investigation period and process specific
experimental program for meaningful results. ·
Composition
of wastewater changed during investigation period. ·
The amount
of matter screened at the treatment plant increased by 77%. ·
20% of
homeowners indicated there had been problems with the disposer, including
blocked pipes, materials caught in the unit and improper installations. |
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Independent Study Data – Hyperion Pilot,
Los Angeles, California |
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The food
waste diverted from Los Angeles World Airport is deposited directly to the
digester at the Hyperion Wastewater treatment plant; there is no possibility
of sewer blockages. ·
The pump
initially used in the pilot plugged with stringy material, such as that found
in celery. ·
Observations
that the food slurry tank must contain systems to address floatables, foam
and settle material. ·
The only
food wastes studied were fruits and vegetables. ·
There was
no indication as to the additional amount of sludge produced in the digester. |