INFLOW & INFILTRATION Reduction in Redcliff

Transcription

1 INFLOW & INFILTRATION Reduction in Redcliff WHAT IS I-I? Inflow and infiltration occurs when water that does not need to be treated enters the sanitary sewage system. INFLOW Inflow is stormwater that enters the sewer systems through improperly connected catchbasins, downspouts, sump pumps and foundation drains, or cross connections between the storm and sanitary sewers. INFILTRATION Find out more at: twitter.com/townofredcliff Infiltration is groundwater that seeps into sewer pipes through damaged or deteriorated pipes and manholes. RAINFALL DERIVED INFLOW AND INFILTRATION (RDII) RDII is the increase in water flow into the sanitary sewer system during or shortly after a wet weather event. Most I-I is caused by aging or improperly installed infrastructure that requires maintenance or replacement. Too much I-I undermines the sewer system and can lead to surcharged manholes, sewer backups, and even flooding in your basement and in your streets.

2 Sources of Inflow & Infiltration IMPROPER SANITARY CONNECTIONS An improper connection lets water from sources other than sanitary fixtures and drains to enter the sanitary sewer system. That water does not need to be treated and should be entering the stormwater sewer system or allowed to soak into the ground without entering the sanitary sewer system. AGING INFRASTRUCTURE On average sanitary sewer pipes are designed to last years. As sewer pipes age, cracks and leaks can form along the pipes and at connections. Groundwater can enter these cracks or leaks wherever sanitary sewer systems lie beneath water tables or the soil above the sewer systems becomes saturated. A single sump pump can contribute over litres of water to sanitary sewer systems in a 24 hour period, the equivalent of the average daily flow from 26 homes. Other I-I sources include basement drains and sump pumps connected to the sanitary system. ENVIRONMENTAL DEGRADATION The intrusion of roots into sanitary pipes not only damages the pipe structure, it also creates a physical barrier, effectively reducing flow capacity within the system. 200 mm sanitary sewer pipes can adequately move the domestic wastewater flow from up to 200 homes, but only eight sump pumps operating at full capacity or six homes with downspouts connected to the sanitary sewer pipe can overload it.

3 Consequences of Inflow & Infiltration Any water entering the sanitary sewer system increases the operation and maintenance costs sanitary infrastructure and exposes property owners to health risks, property and environmental damage. Increased volumes in the sanitary sewers can lead to: Increased cost of transporting and treating higher sewage volumes More frequent maintenance on sanitary infrastructure Reduced capacity in the system which can lead to expensive upgrades, growth restrictions, and increased utility costs for residents. Increased risk of sewer backups into basements and streets creating potential Keeping stormwater out of the wastewater system is critical for the protection of your property, your neighborhood and the environment. health concerns and property damage. Increased risk of groundwater and surface water contamination.

4 Inflow & Infiltration in Redcliff The sanitary system in Redcliff is primarily a gravity supplemented by lift stations and force mains. It is largely comprised of older vitrified clay pipes and newer PVC pipes. A Wastewater System Evaluation completed in 2013 identified capacity issues in the existing sewer system and indicated an increased amount of I-I entering the sanitary system. The Town of Redcliff is working to protect all residents against the consequences of I-I by regulating flows into the Town's sewer system Redcliff Sewer System Bylaws prohibit the discharge of stormwater, surface water, groundwater or roof runoff to any sanitary sewer. It is estimated that over 45% of the Town's Sanitary sewers are more than 40 years old. What is Redcliff doing about I-I? MEASURING AND MONITORING Town of Redcliff Sanitary Flow Levels - June 19, 2012 Rain Event Note: Figure adapted from Town of Redcliff Wastewater Evaluation released May 2013 by MPE Engineering Ltd. A peak in sanitary flow shortly after a rainfall event indicated potential I-I issues upstream of the flow meter. The Town of Redcliff has commenced a number of initiatives to understand the extent and effects of I-I on the Town's sanitary sewer system. FLOW MONITORING The Town of Redcliff monitors sanitary flows on an ongoing basis using flow meters installed in strategic locations around the town. Flow monitoring helps establish a baseline flow level and detects fluctuations in that baseline level over time. When analyzed against rainfall depths, flow data can indicate upstream I-I issues. HYDRODYNAMIC ANALYSIS A hydrodynamic sewer system model will help the Town of Redcliff track I-I levels in the system, evaluate prospective sewer upgrades or I-I mitigation measures, and predict the impact of future development on the sewer system.

5 What is Redcliff doing about I-I? PINPOINTING THE SOURCES Over the coming months a number of field tests and inspections will be conducted to help the Town identify the sources of I-I. SMOKE TESTS Non-toxic, odorless 'smoke' is injected into sanitary manholes. The locations of exiting smoke can indicate where I-I might enter the sanitary sewer system. Smoke will typically appear from roof drains, catch basins or yard drains connected to the sewer system. The smoke may also appear from cracks in the pavement above the sewer; around homes with foundation drains connected to the sewer; or in basements through sump pumps, floor drains, or other direct openings to the sanitary system DYE TESTS A non-toxic dye is added to a stormwater source upstream of suspected I-I locations. The stormwater can then be traced through the system to confirm locations where stormwater is entering the sanitary sewer system TARGETED CLOSED CAPTIONED TV INSPECTIONS A video camera is sent through sections of the sanitary sewer system recording the condition of the pipes. The video footage can help identify I-I problem areas such as cracks, root intrusions, leaks, and stormwater cross-connections. HOUSEHOLD DRAINAGE SURVEYS Keep up to date on I-I tests happening in your neighborhood. twitter.com/townofredcliff Homeowners and business can help identify I-I sources by providing details on the layout and condition of the storm and sanitary infrastructure on their property. As a resident of Redcliff, you will be asked to provide information on weeping tile, sump pumps, basement drains, and drain spout connections, as well as any instances of sewer backups or flooding on your property.

6 What is Redcliff doing about I-I? PINPOINTING THE SOURCES HELP US LOCATE POSSIBLE I-I SOURCES Use a RED sicker to mark where you live if you have experienced a sewer backup in your home, business, or on your property. Use a BLUE sticker to mark where you live if you have not experienced a sewer backup on your property.

7 What is Redcliff doing about I-I? MITIGATION & REDUCTION A Wastewater System Evaluation completed in 2013 identified a number of concerns regarding system condition and capacity. The projected short term upgrades represent sections of existing sanitary sewers that would need replaced or upgraded. The upgrade areas have been selected based on identified capacity issues from the existing wastewater model. In addition to short term upgrades, a number of long term upgrades would also be required to accommodate future growth in the Town of Redcliff. PROJECTED SHORT TERM CAPACITY UPGRADES ESTIMATED COST PRIORITY Area 1 3rd Ave NW from 4th Street to 5th Street NW $ LOW Area 2 Broadfoot Place SW to Main Street $ MEDIUM Broadway Avenue from 1st Street to 3rd St SE, Area 3 1st Street SE fro m 2nd Avenue to 3rd Avenue SE, $ MEDIUM 1st Street SE from 8th Avenue to Mid Block 9th Avenue SE Area 4 2nd Street SE from 6th Avenue to 9th Avenue SE $ MEDIUM Area 5 9th Avenue SE from 1st Street to 20th Street SE/Boundary Road $ HIGH NOTE: All projected upgraded and associated estimated costs have been taken from the Town of Redcliff Wastewater System Evaluation released May 2013 by MPE Engineering Ltd. They are under review following the completion of the hydrodynamic model currently under development. Total $ By reducing the amount of inflow and infiltration entering the sanitary sewer system, the Town of Redcliff hopes to improve system capacity and reduce the need for costly upgrades. Once I-I sources have been identified, the Town of Redcliff will consider a number of mitigation options and establish an I-I Reduction Program. Depending on the location and severity of issues, there are a number of different mitigation strategies ranging from full sanitary replacement and upgrades to less invasive options such as installing pipe and manhole liners and disconnecting known inflow sources such as sump pumps, roof drains, or downspouts. More information on mitigation options and costs, including any actions required by property owners will be made available after all the field tests are complete and the results have been analyzed.

8 What You Can Do Reducing I-I requires your participation. In the coming weeks, the Town of Redcliff will require your cooperation to complete the I-I field tests and surveys. Keep up to date on I-I tests Check your property for any damaged or improperly connected sanitary, stormwater, or drainage infrastructure. Complete the upcoming household drainage survey and report any drainage or flooding concerns. Details regarding testing procedures and requirements will be distributed to your home or office prior to the commencement of testing activities. happening in your neighborhood. twitter.com/townofredcliff If you have any questions or concerns about I-I please contact: There are also a number of actions you can undertake as a property owner to help reduce your contribution to I-I. Disconnect and redirect any sump pumps, roof drains, and downspouts connected to the sanitary sewer system Do not plant trees near sanitary or stormwater Khalil Minhas, Shelley Steckmeister or Jordon Duncan by phone: (403) (403) infrastructure on your property. Reduce your water consumption during high rainfall events to reduce the demand on the sanitary system by i&istudy@redcliff.ca