Report to: General Committee Date Report Authored: May 5, 2010
SUBJECT: Pilot Sanitary System Downspout Disconnection Program Evaluation and Extended Program Implementation Strategy
PREPARED BY: Karen Dennison, Manager, System Engineering, Waterworks Lijing Xu, Sewer System Engineer, Waterworks
RECOMMENDATION:
1)
That the
report entitled “Pilot Sanitary System Downspout Disconnection Program
Evaluation and Extended Program Implementation Strategy” be received; and,
2)
That Council,
through the 2011 business planning and budget process, consider extending the Downspout Disconnection Program
in selected locations, including provision of a financial assistance package;
and further,
3)
That
Staff be authorized and directed to do all things necessary to give effect to
this resolution.
EXECUTIVE SUMMARY:
Not applicable
PURPOSE:
The purpose of this report is to update Council on the completion of the Pilot Area Sanitary System Downspout Disconnection Program (part of Markham’s Inflow/ Infiltration (I/I) reduction effort being tested in the Thornhill pilot area); and to present strategies to extend such a program to selected areas of the Town where it would prove beneficial.
BACKGROUND:
The sanitary sewer system is designed to convey primarily wastewater with a small allowance for I/I and not to carry wet weather flows; however, over time leaks can form for various reasons and increased infiltration will be observed in some of the older areas of the Town. The main inflow sources include items such as directly connected roof downspouts and foundation drain (weepers) or cross connections with storm sewers. These types of connections could have been either built this way originally or over time unauthorized modifications could have been made. All of these conditions make areas prone to flooding during extreme wet weather events.
Downspout connections to the
sanitary sewer system are strictly prohibited under the existing Markham Sewer
By-Law #436-86 and the Regional Municipality of York Sewage and Land Drainage
By-Law # S-0064-5002-009. Even a
small percentage of downspout connections can easily overload the sanitary
system during wet weather events and cause serious social and environmental
problems such as sewer back-ups and basement flooding, sanitary sewage
overflows to natural water bodies, overloading sewage treatment plants and
pumping stations, and reducing system capacity to accommodate more development.
However, in older areas these connections were originally allowed by exception
and the impact on capacity was not considered.
To mitigate this issue in the sanitary system, on April 3, 2008, a Staff Report to Council was made to seek approval for the implementation of a Pilot Downspout Disconnection Program in Grandview area of Thornhill. The pilot program received Council approval on April 29, 2008 and was completed in February 2010.
The purpose of the Pilot Study was to gain first-hand experience, develop & evaluate the program’s implementation strategy, assess effectiveness on reduction of I/I and make recommendations regarding an extended Downspout Disconnection Program, including staging, required resources and funding.
OPTIONS/DISCUSSION
1. Completion of Pilot Downspout
Disconnection Program:
The pilot Downspout Disconnection Program is summarized below. Further details can be found in Attachment A to this report entitled “Further Details & Evaluation of the Pilot Downspout Disconnection “.
The pilot Downspout Disconnection Program was successfully completed in 2010 achieving 100% disconnection compliance within the planned enforcement period (12 months). This success was in part due to the Town’s financial assistance program, a full-time Project Coordinator who liaised closely with residents, and local residents’ receptiveness to the program having been affected by the August 19, 2005 event.
Program Highlights:
i.
Working Group:
A working group was created, consisting of four Councilors and Waterworks staff to develop and oversee a comprehensive approach to conduct the Pilot Program which included the following four major components:
a) Public communication and education
b) Site investigation
c) Downspout disconnection and financial assistance
d) Effectiveness of downspout disconnection
Each component of the downspout pilot project was reviewed for best practices and is summarized below:
a. Public Communication and Education
The public
communication and education program was a key component of the project,
bridging the communication between the residents and the Town and assuring a
smooth and efficient manner to deliver the project. Two newsletters, two public
meetings, multiple notice letters and site visits were completed to liaise with
residents. This component is recommended in any future Downspout Disconnection
Program.
b. Site Investigation
A multi-step investigative approach was undertaken in order to conclusively identify any downspouts connected to the sanitary system. 45 homes were identified as having their downspout(s) connected to the sanitary system, which counts for 6% of the total 766 homes in the pilot study area. This is well within the original estimation of 10% - 15%.
This approach for the Pilot Program was proven to be cost-effective in conclusively identifying downspouts connected to the sanitary system.
c. Downspout Disconnection and Financial
Assistance
Markham’s disconnection program included technical and financial assistance along with progressive By-law enforcement. The financial assistance package was approved by Council to offset residents’ costs and facilitate the compliance process, which included:
(1) 80% of the cost for completing the downspout disconnection, to a maximum of $500;
(2) 100% of the cost up to $150 for a rain barrel purchased by the home owner.
Due to different site conditions, costs for these 45 homes to complete their disconnection work varied from the maximum of $2,596.39 to the minimum of nil (the cost was minimal and the residents did not apply for the subsidy). A total of six homes (13%) purchased a rain barrel. 33 homes (73%) spent less than $500 to complete the disconnection work. Ten homes maximized the Town’s financial assistance amount of $500.
The pilot financial assistance package benefits include:
· A generous package with the actual total cost to the Town being moderate. On average, the total cost for each of 45 home owners was $390. The Town subsidizing $218 of the $390 spent (on average), totaling $9,800 spent by the Town for all 45 homes.
· Reduced Town staff resources through increasing resident compliance and reducing Sewer Use By-law enforcement. It is estimated that the cost to enforce the 45 homes could be as high as $50K for the 45 homes involving three departments; Clerks, By-Law and Waterworks.
d. Effectiveness of Downspout Disconnection
Downspout disconnection from the sanitary sewer was found to be effective in reducing PEAK I/I rates in the local sanitary sewers by 40-50%. Both pre and post downspout disconnection periods were flow monitored in order to evaluate downspout disconnection effectiveness on I/I reduction in the pilot area.
Historically, this pilot area experienced high I/I peak rates during wet weather up to four times the Town’s design standard allowance of 0.26 L/s/ha. After the downspout disconnection was completed, the maximum I/I peak rate was two times the Town’s design standard as observed from a 5-year storm which occurred on July 23, 2009. Note that the intensity of a given 5-year storm is about half that of a 100-year storm. Other I/I reduction measures being implemented and evaluated include manhole sealing and sewer lining to further reduce I/I entering the local sanitary system. Flow monitoring is on-going to help us determine the effectiveness.
ii.
Resources and
Financial Aspects of the Disconnection Program
Total and unit costs of each component in the pilot program is summarized below for the disconnection of downspouts over the total 766 homes in the pilot study area. On average, the Pilot Downspout Disconnection Program cost the Town about $472 per home. This number can be used as a guide for future program cost estimating.
Pilot Program Cost Summary
|
Activities |
Costs
($) |
|
Communication
and Education Program |
$3,830 |
|
Site
Investigation |
$152,980 |
|
Financial
Assistance Program |
$9,810 |
|
Flow
Monitoring Program |
$60,000 |
|
Project
management/coordinate |
$115,000 |
|
Enforcement
(By-law & Clerk) |
$20,000 |
|
Total |
$361,620 |
|
Unit
Cost ($/home) |
$472 |
All investigative work was performed by Waterworks staff to gain experience for any future program management benefit. Waterworks contribution to this project consisted of providing management/coordination, equipment and labour amounting to approximately $272,000 (75% of the costs). Waterworks costs are reflected in the cost summary provided above.
A site inspection was conducted in August 2010, a year after the disconnection was completed, to assure that all disconnections (45 homes) remain in effect. All sites remain disconnected and this has been documented.
2.
Pilot Downspout Disconnection - Going
forward
a) Waterworks recommends site inspections of the pilot area be undertaken annually for the next five years to assure that the downspout disconnection remains in effect permanently.
b) Residents will be informed on the success of the program and thanked them for their participation.
3.
Extended Sanitary System Downspout
Disconnection Program
The Downspout Disconnection Program had proven benefits with respect to reduction of I/I and lessening the risk of basement flooding during extreme rainfall events. Consideration to be given for extending this program to other areas of Town that could benefit in support of Markham’s Town-wide effort to reduce I/I.
Within the Town of Markham, there are three specific older areas (built
before 1980’s); the Greater Thornhill area, Unionville and Markham Village.
These areas do not meet current design standards nor current By-laws. All three
locations have demonstrated high rates of I/I and the potential of downspout
connections to the sanitary system. Downspout disconnection would lessen inflow
and increase service levels. Attachment B provides a preliminary location map
of these potential locations.
Extending the Downspout
Disconnection Program to other areas of Town will further support Markham’s
Town-wide I/I reduction effort, the Town-wide Flooding Control Implementation
Strategy prepared by Asset Management Department, and the York Region’s I/I
reduction program as mandated in March 2010 by the Ministry of Environment in
their conditional approval of the Southeast Collector Trunk Sewer Environmental
Assessment.
Asset Management is not recommending disconnection of downspouts from the
storm system at this time.
Activities in any extended Downspout Disconnection Program would include
public communication and education, site investigation, financial assistance,
flow monitoring, project management and customer coordination and By-law
enforcement.
Please note that all site investigation activities in the pilot program (lot inspection, smoke testing, dye testing) were conducted by Waterworks in-house resources; however, this in-house effort is not sustainable for the magnitude of this extended program.
Waterworks, through the 2011
business planning and budget process, will provide program phasing, resource
requirements, financial assistance request and funding needs to carry out an
extended Downspout Disconnection Program in efforts to proactively reduce I/I
and basement flooding in areas that can benefit from such a program.
FINANCIAL CONSIDERATIONS AND TEMPLATE: (external link)
Should Council consider a phased extension of this Downspout
Disconnection Program to the three oldest areas of Town, the costs would be in
the neighbourhood of $5.3M to be implemented over a 6-8 year period.
HUMAN RESOURCES CONSIDERATIONS
If there is a decision to proceed the extended Downspout Disconnection Program in the three oldest areas of the Town, two full-time staff positions are required, a Project Engineer and a Project Coordinator to manage contractors and coordinate with the public.
ALIGNMENT WITH STRATEGIC PRIORITIES
This project aligns with the Building Markham’s Future Together program, improving the areas of Managing our Growth, Protecting our Environment and Excellence in Municipal Services. Disconnecting roof downspouts from the sanitary sewer system in accordance with the Town’s By-law, has extensive and long lasting environmental benefits which include reduced energy costs for sanitary sewage pumping and treatment, ground water recharge, water conservation, reduced probability of sanitary sewer backups into basements and sanitary sewer overflows to receiving waters.
BUSINESS UNITS CONSULTED AND AFFECTED:
The Business units which will be most affected by the proposed extended Downspout Disconnection Program include Waterworks and By-law Enforcement.
RECOMMENDED
BY: ________________________
Jerry Klaus
General Manager, Waterworks
________________________
Peter Loukes, P. Eng.
Director, Operations
________________________
Brenda Librecz
Commissioner, Community and Fire Services
ATTACHMENTS:
Attachment “A” – Further Details & Evaluation of the Pilot Downspout Disconnection
Program
Attachment “B” – Markham Sanitary System Downspout Disconnection Implementation
Areas