Executive Director Rogers reported that the Park Board’s stormwater subcommittee met with the City on January 14, 2016 at City Chambers with six residents in attendance and two providing public comment. The Park Board stormwater subcommittee reiterated the Board’s position statement on the requirement of a shut-off valve in the proposed York Commons stormwater detention basin. The subcommittee then agreed to grant the City’s request to have the District’s engineering firm, V3, provide a written opinion on the shut-off valve and respond to specific inquires, but reminded the City that the Park Board is firm on the stipulation of a shut-off valve.
In regards to stormwater detention at Golden Meadows Park, the City stated that within the next month, the Park Board’s proposal, which the City's stormwater subcommittee has agreed to, needs to go to the Public Works Committee and then on to City Council. On January 13, the District received a letter from the City requesting the Park District forego the replacement of compensation for East End, Wild Meadows Trace and Crestview park sites and instead work with the City to ask IDNR to make an exception to their policy restricting off-site stormwater detention. The City assured the request would include possible improvements to these parks to facilitate the construction of stormwater basins, but the request was not forthcoming. The next stormwater subcommittee meeting is scheduled for February 18, 2016.
On January 18, 2016, Commissioner Graf and Executive Director Rogers attended the City Council meeting where, during public comment, Rogers read the Park Board’s position statement requiring a shut-off valve at York Commons to prevent an adverse impact to park neighbors. At that meeting, the City Council voted ten to zero with four absences to approve the proposed IGA without the shut-off valve. Mayor Morley and Alderman Kennedy provided a presentation on the concept of the valve. On Tuesday, January 19, 2016, the District received a letter from the City summarizing the City’s amended IGA with a request to have V3 Engineering respond to four questions.
Mr. Wolterstorff read written responses to the City’s inquiries.
Question 1: Does the proposed project meet the DuPage County Ordinance requirements without the valve?
V3 Response: V3 believes that the proposed project would meet the requirements from the DuPage County Ordinance for all critical duration storm events up to the 100-year, 24 hour event.
Question 2: Based on V3’s review of Burke Engineering’s stormwater analysis, would providing additional storage in the future basketball and sand volleyball court area mitigate the downstream impacts for 500-year, non-critical duration storm events?
V3 Response: V3 has not modeled the system to evaluate impacts of the 500-year storm event nor does V3 have enough information from the Burke Engineering table to determine the required stormwater storage to mitigate the downstream impact associated with the 500-year overflow from the proposed York Commons basin.
Question 3: Is the installation of a shutoff valve a necessity for this project?
V3 Response: Based on the tables provided by Burke Engineering on December 1, 2015, the “proposed conditions” without a valve demonstrates an increased 500-year discharge to York Street which occurs through the Overflow Weir, when compared to the “with shut-off valve” scenario which shows no overflow. V3 understands that the Elmhurst Park District has consistently expressed a concern for implementing a solution that may shift flooding problems from one location to a new location. The shut-off valve would prevent this overflow and maintain existing conditions at Crescent Street for storms exceeding the 100-year event.
Question 4: If V3 is stating the valve is a requirement, have they modeled the impact of the valve in the proposed system and can they state what level of flooding will be experienced by the homeowners either upstream or downstream of the valve?
V3 Response: V3 has not performed modeling of our proposed system. V3's responses are based upon V3’s review of the data and information provided by Burke Engineering.
V3’s responses will accompany a letter from the Park District reiterating their request for a shut-off valve. Executive Director Rogers stated that as stormwater management is not the responsibility of the Park District, V3 was contracted to conduct a peer review and not modeling. With a valve installed, Crescent Street will be the only street to back up during events greater than a 100-year storm. The Park District is committed to being part of the solution without exasperating the existing problem. The type of valve requested is much less complicated than the pumps already used to manage stormwater along Salt Creek. The Burke Engineering plans are not sufficiently complete to illustrate the overflow route; as a result the overflow may travel west to the street or south into the York Commons parking lot. Either route will end up at the intersection of York and Cayuga. Commissioner Spaeth added that it is difficult to predict the size of storms thus causing more concern for residents’ safety. Improved infrastructure remains the less expensive route to provide flood relief to residents.