06-27-2016 Council Packet - Laserfiche WebLink

Home Search

Mr. Michael Grochala May 19, 2016 Page 2 Option 1C: Direct Developed Runoff To ACD72 This option would use the existing ACD 72 alignment south of Eagle Brook Church and north of 77th Street East (Figure 3) and would replace the existing drain tile with 72‐inch storm sewer to serve the study area. This option would also include additional regional storage ponds to the west of Eagle Brook Church and on City‐owned parcels off of Rehbein Street. Since the alternative is utilizing the existing alignment for ACD 72, there are existing easements in place and no additional acquisitions would be necessary. Unfortunately due to the existing topography along this alignment, a large portion of the study area on the west side would be unable to connect to the new storm sewer. In order to benefit the entire study area, an additional outfall is still required. This option was not considered for further analysis in the feasibility study. Option 1D: New Outfall with ACD72 Due to the limitations of using the existing ACD72 alignment, a modification to Option 1A was considered. This option continues to use the ACD 72 ditch system for the northern portion of the study area, but includes a new outfall to Peltier Lake (Figure 4). This option would allow for the different timing of development within the watershed and facilitate the Watermark development in the short term, while providing flexibility for future development in the northern portion of the study area to tie into ACD 72 or the new outfall. Additional analysis would be required to determine the ultimate pipe sizes to accommodate the entire drainage area through these two outlets. Option 1E: New Outfall with ACD 72 and ACD 55 This option is the same as 1B, however would also use the available capacity in ACD 55 in the southern portion of the watershed for future development (Figure 5). This option would need to be evaluated to ensure no adverse impacts to Clearwater Creek occur due to increased discharge through ACD 55, as well as to determine required pipe sizes. OPTION 2: NORTH OUTFALL This option aligns the new outfall to the north of the study area and would allow landowners to vacate some of the existing drain tile on their property in the interim condition, as well as require minimal easements and avoidance of existing wetlands. It does remove approximately 60 acres from the benefitted area and limits the siting of regional storage facilities (Figure 6). Option 2A: North Open Channel The initial alignment considered an open channel; however it was removed from consideration in the feasibility study due to concerns over cost and land acquisitions. Option 2B: North Storm Sewer The second north outfall option considered the same alignment, but using storm sewer, rather than an open ditch. This reduces the amount of land acquisition necessary from 100‐feet, on center, to roughly 70‐feet. OPTION 3: SOUTH OUTFALL This option would align the new outfall through existing wetlands and the reconstruction of Peltier Lake Drive along the final 700 feet of pipe (Figure 7). This option would serve the entire study area; however, it may prove difficult for landowners south of Rehbein Street to tie into the new storm sewer along the southern border. Land acquisition through this alignment would be less costly due to the presence of wetlands, than through the more developable upland area. Care must be taken during installation not