Saturday afternoon September 7, parts of Provo (primarily the Grandview and Carterville areas) received an historic rainstorm. The BYU Weather station recorded nearly 50 mph winds and 0.8” inches of rain (0.6” of that in about 15 minutes). Given the relative quantities of runoff observed, and the damage received; we believe the total rainfall in the hardest hit areas was nearly double that, with about 1” during the most intense 20-30 minutes between 4:00 and 4:30 pm. This would equate to more than a 50–year event.
As an indication of the magnitude of the storm, flows in the lower Provo River went from 20 cfs at 4:00, to almost 600 cfs at 6:00 pm Saturday. While flow increases in the Provo River of 200 – 300 cfs after storm events are not uncommon, an increase of 600 cfs is extremely rare.
There were several areas where runoff exceeded the capacity of existing storm drain systems. We are aware of at least a dozen homes that experienced flooding, mostly in the Grandview area.
Surface water flowing off the Grandview hill caused damage and left debris in several areas.
900 N / Grand Avenue
Storm water washed out a portion of the street and deposited gravel and mud on the property below, including along 820 North Street. This road segment is currently closed, and will require reconstruction. The office building at 1680 West 820 North has gravel and mud stacked up against the north wall, and within portions of the building.
1460 N and 1150 N, Jordan Avenue
Overflowing water undermined support for the concrete pedestrian stairways at these two locations and deposited gravel and mud in Lion’s Park. We are not aware of any private property damage associated with these incidents. The stairways are unsafe, and have been closed. At least a portion of both stairways will likely require removal.
1060 W 2300 North
Water in the privately owned West Union Canal overflowed its banks, washing away some landscaping improvements and causing flooding in a number of homes in this area; as well as depositing gravel and mud on local streets.
Beyond the hardest hit areas, street flooding was reported and observed throughout the community along, and west of University Avenue; mostly in the southwest, west central and river bottom neighborhoods. Many of these streets have deposits of sand and mud that the City has been working to clean up. Several affected storm drains will be inspected and cleaned to preserve capacity.
The winds that accompanied the rain generated some tree damage. Small branches and leaves contributed to some of the street flooding by clogging storm drain inlets.
Pursuant to concerns expressed from effected property owners, sandbags and sand have been made available at the Public Works yard. We know that a few hundred have been filled and used by residents in the Grandview area.