Stormwater Master Plan reviewed

by Austin Stanton

I have read the Stormwater Master Plan published by Christopher B. Burke Engineering, Ltd dated July 2003 for the City of Des Plaines, IL.

To place our beliefs before the detail below, we believe that the City should strongly consider  revisiting the design standards for the proposed options since the comments below show that the proposed solution may fall short of the necessary requirements and expectations for our area. The City should take into account the results of the questionnaire/survey results that we produced last summer. The proposed solutions were based on virtually no input from our area.

The entire document is 140 pages, and currently is not publicly available in its entirety, so you can look here for the portions of the report relevant to the comments below where important key passages have been noted.

My comments about this report are as follows:

1. It is unclear when The City sent out the Flood Protection Questionnaire. The report implies that it was sent out after the 2001 flood event, but it may have been in 1986. Burke includes a separate table that documents phone calls received by The City during the 2001 event. It is important to note that there were very few respondents in our ward. I have no recollection of receiving the questionnaire, and I have been here since 1995.
2. The Plan is an update to the 1986 Storm Water Master Plan.
3. The proposed solutions are designed to handle the October, 2001 rain event (p 75), which was 3.8 inches of rain in 3-4 hours. This is close to last June’s event, but significantly under the September, 2008 event.
4. The report briefly addresses rear yard flooding (p. ES-3) and provides an estimate, but this issue appears to be outside the scope of this plan.
5. The priority list (p.ES-4) lists our area as the 4th highest priority. The highest priority area is in The Highwood Knolls. They have or had a significantly higher weighted score, by far, than any other area. This can probably be linked to the high level of responses to the questionnaire. Therefore, the lack of responses from our area may have hurt us.
6. On page 28, the report states that the “existing Marshall Drive storm sewer has insufficient capacity to convey tributary October, 2001 historic storm event runoff”.
7. On page 31, it states the same thing for the Pennsylvania Avenue storm sewer. These sewer systems are undersized. This is a critical piece of information.
8. Page 41 states the extent of the October, 2001 event and discusses the methods used to arrive at their recommendations.
9. Pages 73-77 provide a detailed description of how the storm systems in these 2 areas work. There are various alternatives that are discussed and evaluated; some are quite impractical, such as buying Friendship Park and turning it into a detention pond.
10. Alternative 1A solves the problem for Area 8 at the expense of Area 9. Alternative 1B is recommended to be used in conjunction with 1A. However, this is dependent on the existence of “the proposed Wille Rd. storm system”. It is not clear if that system was built. Note that Spaceco is the surveying division of Christopher Burke Engineering, so it should be assumed that the information they provided is accurate. Also, as I suspected, there are many technical difficulties with this option including easements and existing utilities. It is stated that if Alternatives 1A and 1B are done, flood protection for Area 8 is achieved during the October, 2001 event and “acceptable flood levels of 4.1 inches” occur at Pennsylvania and Oakton. This means that any event that exceeds the October, 2001 event would result in flooding exceeding 4.1 inches at Pennsylvania and Oakton.
11. Option 2, which seemed to be the most practical, won’t work due to existing elevations.

However the most disturbing aspect of this report by far, is addressed on Page ES-3. The report addresses the issue of the sanitary system surcharge. It recommends that the burden for this problem be put on the homeowner. I think that it is erroneously assumed that this problem is due to a combined sewer system, which we don’t have in our areas. Again, I believe that the proposed solution for our area will have little or no impact on the issue of the sanitary sewer surcharge. This should become a priority for us.

Going forward, we should determine if the City is going to revisit the design standards for the proposed options. Under the circumstances, the proposed solution may fall short of the necessary requirements for our area and almost certainly fall short of expectations. The City should take into account the results of the questionnaire/survey results that we produced last summer. The proposed solutions were based on virtually no input from our area.