Regarding the Intense Rain Event Friday Evening–5/15/09.
The storm was a fast moving storm that produced large amount of rainfall in a very short period of time. The rain gauge at Healey Street recorded 1.41-inches in a 15 minute period. Of the 1.41inches, approximately .72-inches fell in a 5 minute period. According to the Illinois State Water Survey, .72-inches of rainfall in a 5 minute period equates to a 100-year return interval. 1.41-inches in a 15 minute period equates to approximately a 25-year return interval. Over the next 1 to 2 hours 2.5 to 3 inches fell depending on where you were at in the City. Saturated ground conditions from the storm on 5/13/2009 contributed to the excessive runoff from the 5/15/2009 storm. Storm sewers throughout the City were overwhelmed and unable to keep up with the runoff generated from the storm.
Public Works Operations staff were called in to work in response to heavy rains at about 6:45 PM Friday 5/15. Six employees responded under direction of the sewer section supervisors.
Police began reporting flooded viaducts and flooded streets across wide areas of the city. Initial priority was to barricade hazardous flooding locations. After securing the viaducts and major streets crews moved to flooding on neighborhood streets. While flooding was reported across the city, the viaducts, South Neil St.. N. Mattis Avenue , John St. east of Prospect ( 500 and 600 blocks of West John, the area around the intersection of McKinley and Washington all experienced significant flooding.
Flooding began to abate after the rains slowed with many areas going down after 9:30 PM.
As flooding response became less critical crews began responding to reports of basement back ups. These locations were checked to determine the cause of the back up and to see if any actions could be taken to alleviate the problem.
Crews stayed on duty until after 2:00 am Saturday and some employees returned to work Saturday to clean the viaducts
The Engineering Division is currently responding to approximately 50 follow-up calls for service. More are expected over the next few weeks. We are still trying to complete the follow up from the storm the week before. We will continue our efforts until everyone is contacted and followed up with. Public Works staff will also continue meeting with the John Street watershed steering committee and will soon be meeting with some of the citizens in the Washington Street neighborhood as well to discuss their problems and issues.
On the bright side, the Healey Street basin and the enclosed channel from 1st to 6th street have performed well over the last several years and other improvements that the City has caused to happen such as the extra storage at the upstream end of the Phinney Branch water shed has dramatically decreased the areas of the older parts of the City where we saw consistent flooding in the past. In the case of the Boneyard Creek improvements–the possible solution to the John Street problems would not be possible with out that prior improvement. These longer term solutions of-course take considerable time and money to implement.
Also, we have also helped homeowners install numerous overhead sewers that have solved many individual basement flooding problems, we also provided troubleshooting on other plumbing and drainage issues. Both staff and homeowners are looking forward to some dry weather.
We will continue our efforts to work in partnership with the impacted neighborhood, to continue dialogue and to try to address their problems to the extent possible. If you have any questions feel free to contact me.
Sincerely,
Roland White, P.E.
City Engineer
City of Champaign
Public Works / Engineering Div.
702 Edgebrook Dr.
Champaign, IL 61820
Phone 217/403-4710
Fax 217/403-4755
