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Regular Planning CommissionMeeting Minutes –Wednesday, December 2, 2015 Page 5 that Mr. Mueller keep his existing beautiful home and build one additional home onthe 198 extra lot, similar to that done by others in that neighborhood. 199 Engineer Chuck Plowe 200 Regarding concerns raised during public comment about the level of groundwater in 201 basins, Mr. Plowe reported that soil boring information indicated to engineers designing 202 them, that their design should be 3’ or more below water basins for infiltration and for the 203 drain tiles to function properly.Mr. Plowe noted that all of these designs would require 204 review and approval by the City Engineer as well as engineers with the Watershed 205 District.Regarding those levels, Mr. Plowe advised that they were typical for down water 206 streams, with water infiltrating and percolating onto adjacent properties with tight soils, 207 thus the reason for drain tiles without the advantage of sandy soils, negating the need for 208 the drain tile system.Mr. Plowe clarified that engineered soil materials would be installed 209 above those drain tiles with the intent to make the water drain down into that system. 210 In response to Mr. Ramalingam’s questions related to the ponds, and whether they would 211 be dry before the next rainfall event begins, Mr. Plowe responded that typically they 212 would be as the soil media and drain tile draws that water level down over a 48-72 hour 213 period; but again noted the City Engineer and Watershed District engineers would also 214 review and ultimately approve the stormwater management plan. 215 Specific to groundwater levels, Member Murphy sought clarification that in order for this 216 design as proposed to pass muster, it needed to be at least 3’ less than the number 217 needed; with Engineer Plowe responding affirmatively. 218 Specific to the removal of trees and impacts to the soil evaporation rate, Member Murphy 219 asked Mr. Plowe if that was a common consideration in site drainage plans. 220 Mr. Plowe advised that it was, and in developing the whole design, both existing condition 221 calculations and redesigned or proposed calculations were taken into consideration, 222 including taking into account added impervious surfaces and how much additional runoff 223 would occur and not be infiltrated; providing the overall system design. 224 At the request of Member Murphy, Mr. Plowe stated that removal of trees for grading and 225 other redevelopment needs could not be specifically calculated at this time, but 226 evaporation and runoff is taken into account. 227 Chair Boguszewski asked if Mr. Plowe was confident that the 8” drain on Acorn Road 228 would suffice. 229 Mr. Plowe responded that he was confident; and when reviewing the basins and 230 infrastructure, there would continue to be some overflow as there is today, but the intent 231 was not to have a lot of flow go through the 8” infrastructure system, but available to 232 handle a 2-year rain event.Mr. Plowe opined that the system would prove adequate for 233 short-term ponding and with smaller storm events thatwould not be much water for any 234 length of time, but that it was taken into consideration in designing the stormwater 235 management system. 236 As noted in the staff report, and confirmed by Mr. Plowe, Member Murphy stated that the 237 City Engineer’s review of the plan and his input indicated the new pipe would still be 238 accommodated by the existing downstream system on Acorn Road; with a minimal 239 amount of additional water added to that storm sewer system and not creating any 240 additional problem. 241 C hair Boguszewski closed the public hearing at 7:15p.m.; no one else spoke. 242 Member Cunningham noted that she had supported the last four proposals, and opined 243 that this latest proposal from the applicant provided even more significant improvements 244 and commended Mr. Mueller for listening to his neighbors and addressing their concerns. 245 Member Cunningham stated her main concern in the past was with the road width and 246 tree issues, as well as significant drainage issues; but again noted Mr. Mueller appeared 247