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7. INSTALLATION OF INLET CONTROL DEVICES – STATUS UPDATE
INSTALLATION DE DISPOSITIFS DE CONTRÔLE DU DÉBIT – COMPTE RENDU
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Committee recommendation
That Council approve the implementation of protocols related to the installation of Inlet Control Devices as outlined in this report.
Recommandation DU Comité
Que le Conseil approuve la mise en oeuvre de protocols concernant l’installation de dispositifs de contrôle du débit, comme l’explique le présent rapport.
Documentation
1. Deputy City Manager's report Planning, Transit and the Environment dated 3 May 2010 (ACS2010-ICS-INF-0008).
Planning and Environment Committee /
Comité de l'urbanisme et de l'environnement
and Council / et au Conseil
Submitted by/Soumis par : Nancy Schepers, Deputy City Manager/
Directrice municipale adjointe, Infrastructure Services and Community Sustainability/Services d 'infrastructure et Viabilité des collectivités
Contact Person/Personne ressource : Wayne Newell,
General Manager / Directeur général, Infrastructure Services / Services d'infrastructure
(613) 580-2424 x16002, Wayne.Newell@ottawa.ca
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Ref N°: ACS2010-ICS-INF-0008 |
SUBJECT: |
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OBJET : |
INSTALLATION DE DISPOSITIFS DE CONTRôLE DU DÉBIT – COMPTE RENDU |
REPORT RECOMMENDATION
That Planning and Environment Committee recommend Council approve the implementation of protocols related to the installation of Inlet Control Devices as outlined in this report.
RECOMMANDATION DU RAPPORT
Que le Comité de l’urbanisme et de l’environnement recommande au conseil d’approuver la mise en oeuvre de protocols concernant l’installation de dispositifs de contrôle du débit, comme l’explique le présent rapport.
BACKGROUND
At its meeting on 13 October 2009, the Planning and Environment Committee approved the following motion (ACS2009-CCS-PEC-0024) brought forward by Councillor Feltmate:
Whereas the City of Ottawa’s Design Guidelines has been shown to provide a high degree of protection against flooding during storm events, and
Whereas Inlet Control Devices are one of the measures that City’s Design Guidelines utilizes to prevent against basement flooding, and
Whereas in new developments or city projects, where projects are still under construction, it is prudent to ensure that Inlet Control Devices are installed as early as possible;
Therefore be it resolved that City Construction Inspection staff develop and implement protocols by January 2010 that require a professional engineer to certify that all required Inlet Control Devices are properly installed and inspected prior to permitting a new storm sewer to connect to the City’s existing storm sewer system.
PEC, at its meeting on 13 April 2009, considered a report prepared by Councillor Feltmate regarding the Requirement for Inlet Control Devices. Committee approved the following recommendation:
“That the Planning and Environment Committee recommend Council approve that, until such time as new protocols are finalized and approved by Council, staff be directed to permit connections to the existing storm sewer system provided that a flow limiting orifice plate, designed by an engineer to the satisfaction of the city, be installed at the storm water outlet prior to connecting upstream storm sewers”
Council will consider the item at its meeting on 28 April 2010.
The purpose of this report is to recommend the implementation of protocols related to the installation of Inlet Control Devices (ICDs) and outline measures to protect downstream storm and sanitary sewer systems from stormwater inflow in areas under construction until all control measures have been completed.
DISCUSSION
Through the ongoing flooding investigation, staff identified an increased flooding risk to homes both in new developments and in existing areas connected to sewers located downstream of new developments. These risks are present in both storm and sanitary sewer systems and are due to stormwater inflow into storm and sanitary sewers beyond design levels during construction during heavy rainfall.
Storm Sewer System
In keeping with the Council motion, to increase the level of protection for new homes and for those located on downstream sewer systems, staff considered the following options:
Option 1 – That no connection to an existing system be allowed until all the ICD’s have been certified by a Professional Engineer as per the Council motion. This option has been enforced since January 2010.
Certifying that all ICDs have been installed prior to the connection to the City’s existing storm sewer system would mean dramatic changes to existing construction practices. This option is not recommended.
Option 2 – That connection to an existing system be allowed, pending ICD certification, if there is a complete blockage of the outlet to the receiving storm sewer. This blockage would only be removed upon certification of the ICDs.
Allowing a connection, with the outlet being fully blocked, would protect the existing system prior to ICDs being certified. Although this option protects the existing system, it simply dams the water and does not manage the water in a controlled manner. This option is not recommended.
Option 3 - That connection to an existing system by allowed, pending ICD certification, with a designed and installed flow restrictor at the connection point. The flow restrictor would be sized to prevent the flow from exceeding design levels of downstream sewers.
With the protection to the existing system designed, installed and certified at the connection point, certification of the ICDs can be subsequently completed at the appropriate time. This option also minimizes impact on existing construction practices. This is a modification to the Council approved motion, but respects the intent to provide the additional levels of protection, while minimizing impacts on existing construction practices. This option is recommended.
Sanitary Sewer System
Protection of the sanitary sewer system was not specifically outlined in the Council approved motion. Given there is a risk of uncontrolled stormwater inflow into the sanitary sewer system during construction, additional protective measures are also being implemented by requiring that a plug be installed at the connection point to the existing sewer system. The plug would remain in place until the first dwelling is occupied.
Implementation of New Protocols
The Sewer Design Guidelines are being amended to reflect the proposed design and installation of flow restrictors to protect the existing sewer systems. Amendments are also being made in 2010 to the standard construction specifications to include the requirement for the additional flow control provisions and the certification of ICD installations.
On development projects, the certification of ICD installation will be required prior to issuing building permits. Building permits are not issued until such time as preliminary approval to base course asphalt (or granular “A” in winter conditions) is issued by Planning and Growth Management. This certification will be required prior to granting preliminary approval.
On city construction projects, the amended standard construction specification will be used for 2010 projects to include the requirement for the certification of ICD installations. The submission of this certification will be required prior to the placement of base course asphalt.
Except where properties are connected to municipal storm sewer systems in rural villages, this report is not applicable.
Staff from Infrastructure Services, Environmental Services and Planning and Growth Management provided input for this report.
City staff outlined the key changes at the Engineering Liaison Sub-Committee at its meeting of February 26, 2010.
COMMENTS BY THE WARD COUNCILLOR
This is a Council approved Motion and addresses a City-wide issue; therefore a Councillor comment is not required
There are no legal or risk management implications from adopting the procedures outlined in this report.
This report is consistent with the Service Delivery priority of the City Strategic Plan.
N/A
There are no new financial implications associated with this report. The requirement for the installation of ICDs already forms part of the City’s Sewer Design Guidelines. This report clarifies when these are to be installed.
Infrastructure Services Department will amend the City’s Sewer Design Guidelines and standards construction specifications to include the additional flow control provisions and the certification of ICD installations. They will also implement these changes on upcoming city construction projects.
Planning and Growth Management will ensure the new requirements are implemented on developer built projects.