This is Day 6 of the incident.
As a part of our data collection process, we have collected rainfall data and weather information to better understand the nature of this event. The weather forecast did not indicate any risk of heavy rainfall overnight on July 13th into July 14th. The forecast called for only 0.3 mm of rain between midnight and 3:00 a.m., and a total of 4.1 mm of rain between 3:00 p.m. on July 13th and 6:00 a.m.on July 14th. Radar data shows a small cell entering the area around the time of the event and clear skies in surrounding area. Data provided by the Region of Peel at a gauge near the flooding location shows 37.6 mm of rainfall beginning around 11:00 p.m. on Thursday, July 13th. This is consistent with the City’s data which shows 32 mm of precipitation falling between 11:50 p.m. and 12:30 a.m.
Water Infiltration Issue – July 14, 2017.
The forecast continues to vary, with a mix of sun, cloud and showers for the remainder of the week. There is a chance of thunderstorms this afternoon clearing tonight, and again tomorrow. Pumps have been set up in advance of today’s forecasted event and staff will be monitoring conditions throughout the day.
Impacted Residential Properties
- 23 residential properties affected in Wards 9 and 10.
- 22 properties in Ward 10 located on Black Walnut Trail
- 1 property in Ward 9 Status:
- Data collection is ongoing.
Our consultant has downloaded information from the storm sewer system, Foundation Drain Collectors (FDC) system and trench system. Early analysis shows that this event caused rapid water level increases in all three systems, with a slow decrease in the trench system. The character of these water levels appears to be different than those observed during other significant rainfall events.
- Information will be collected from the remaining data loggers in Lisgar neighbourhood this week, including the creek.
- Our consultant will provide a memo outlining their data observations by the end of next week.
- This rain event exceeded a two year storm and approached a five year storm, which exceeds the capacity of the storm sewer designed for this area. This likely caused water ponding on the roads in some areas, although no observations have been reported.
- Closed-circuit television (CCTV) inspection of the FDC system along Black Walnut Trail has been completed and will be provided to our consultant for review.
- Preliminary observations show three points of water infiltration into the system possibly due to deterioration of fitting connections.
- Further from the inspection, mineral deposits were identified within the system and require clearing.
- The FDC system will be flushed out by next week, subject to weather conditions.
- The CCTV inspection area will expand today to include the trunk FDC sewer system (as it continues south, parallel to the Lisgar Meadow Brook Trail).
- In addition to the above, other factors being investigated include:
- the elevation of basement floors of the homes along Black Walnut Trail, and
- potential additional sources of water to the FDC system.
- The Region of Peel is continuing with visits to remaining homes affected by water infiltration. These homeowners will be asked to measure elevation from basement floor to the windowsill of a side/front facing basement windowsill.
- Works Operations and Maintenance staff have been monitoring the creek and pond in the area. Creek levels have come down, while pond levels remain high. This is not unusual.