03/22/2004 Council Packet - Laserfiche WebLink

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Eagle Brook Church page 8 Watershed in lieu of the suggestion to daylight the underground "ditch" and make it an actual surface ditch. The new underground tile will daylight in a location similar to the existing tile, and discharge into the wetland. The capacity of the tile will not be changed. The ditch must not be impeded so as to cause flooding. On the other hand, increasing the ditch's capacity could drain wetlands in the area. Therefore, design of any work that affects the ditch must maintain ditch capacity. The applicant will be required to enter into a ponding maintenance agreement with the city. Drainage and utility easements must be created over all ponds and wetlands on the final plat. Easements must be placed over the relocated drain tile for Co. Ditch 72 and deeded to the Rice Creek Watershed District. As a condition of plan approval, the grading and drainage related modifications and comments as set forth in the City Engineer's memo should to be incorporated into the plans. Clarification of the County Ditch Drainage Area and Affect On Design: Residents raised a question about the area being drained by the county ditch as it exists now. The Watershed District has stated about 600 acres. Residents say the drainage area is much greater. Private drain tiles typically are not all documented. It is impossible to know how many private landowners have installed tiles that cross a natural subwatershed boundary, which would increase a drainage area for a downstream tile. However, this question is a red herring. Regardless of the drainage area, the drainage rate of the tile /ditch must not be altered. This is the salient point. The drainage design must maintain the existing flow capacity. Effect of the Impervious Surface On the County Ditch: The county ditch will be re- aligned. The proposed drainage design does not route runoff from new impervious surface into the county ditch. Runoff from the parking, building, etc., will flow through a series of facilities into a stormwater pond, then into the wetland downstream from where the ditch discharges into the wetland. The church project will not increase flow in the county ditch. Phosphorous Discussion: Residents have claimed that the phosphorous reduction on the site is not enough to meet City policy. The claim refers to a study in 1993 that reduction of phosphorous is desirable. The claim also references a goal of the St. Paul Water Utility of a specified phosphorous level for the lake. These documents do not establish City policy. Nor is the City the permitting jurisdiction for wetland or surface water permitting issues. The Rice Creek Watershed District holds those authorities, and the RCWD granted a conditional approval of the proposed church project in October 2003. The approval states that the stormwater management design "meet District water quality treatment, rate control, and infiltration requirements." Floodplain: The city has a floodplain management ordinance. The 100 -year flood elevation, which defines the floodplain, is 887. The western portion of the site is within the floodplain. Lowest floor elevations of structures must be at least one foot above this Resolution 04 -17, page 8