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Regular Planning Commission Meeting Minutes – Wednesday, August 3, 2016 Page 7 and medium density residential (MDR), involving parcel area measurements as 306 part of the calculation, seeking to provide some consistency and realistic 307 measurements that didn’t prove arbitrary in nature. 308 Mr. Lloyd briefly summarized his understanding of engineering staff’s hydrology 309 analyses to determine runoff based on lot coverage and under certain rain event 310 percentages. Mr. Lloyd noted engineering staff found plenty of capacity at a 30% 311 level, and that it could still be adequately addressed at 40%, but that 50% was 312 beyond their comfort level. As part of their technical analysis, Mr. Lloyd advised 313 that the engineering staff had reviewed existing LDR properties and approximated 314 impervious surfaces on those properties, finding them to be at about the same 315 level; substantiating their recommended 40% hydrology percentage as an 316 acceptable level. 317 Member Gitzen asked if there was a standard definition in city code for “pervious” 318 and “impervious” especially in light of newer technologies and permeable pavers 319 now allowable while still meeting coverage allowances. 320 Mr. Lloyd noted there were definitions, but also clarified that this involved more 321 than just talking about different kinds of pervious or impervious treatments or 322 pavements, but included filtering through grass and provided several examples 323 (e.g. beehive cement pavers and Geogrid products) that were between 324 impervious and pervious surfaces that required staff and the city to understand 325 the product being proposed going forward, how it would be installed and 326 maintained, and then pro-rate those areas and type of material used accordingly. 327 Mr. Lloyd noted this added complexity to those calculations for either surface 328 area. Mr. Lloyd referenced a pervious asphalt parking lot installed by the Rice 329 Creek Watershed District on the other side of Rice Street, as well as addressing 330 the added costs for these newer materials at this point in time, as well as 331 agreements to address long-term maintenance to ensure the materials continue to 332 work as permeable applications. 333 At the request of Member Bull, Mr. Lloyd further reviewed the hydrology tests on 334 typical LDR-2 and LDR-1 lots, with far fewer LDR-2 lots in Roseville and the 335 rationale that if higher impervious surfaces are allowed on LDR-2 lots it may 336 overtax the storm water system downstream. However, in addressing the square 337 foot minimum lot sizes and comparing LDR-1 and LDR-2, Mr. Lloyd noted it made 338 more development possible on smaller lots, if calculations were more than the 339 current 30%, but less than the originally requested or proposed 50%. 340 Member Kimble stated she found proposed language on Attachment A, lines 32- 341 33 related to residential water permits based on the findings of the city engineer 342 and intended mitigation somewhat ambiguous. However, the redlined copy 343 following that defined more specific language; with Member Kimble asking if that 344 should be more consistent. 345 Mr. Lloyd clarified that the language was intentionally ambiguous in light of the 346 aforementioned proposed stormwater permit process being drafted by the Public 347 Works Department as an optional tool for those property owners exceeding their 348 impervious coverage allowances and paying a fee to be accumulated with others 349 for a broader stormwater improvement project or system. If the first part of the 350 language is more specific at this point, Mr. Lloyd noted it would have to be revised 351 again if and when that tool becomes available. 352 Member Kimble recognized that intent; however, she opined it looked like there 353 was no defined standard and that the engineer could decide independently and 354 arbitrarily for each applicant. Specific to mitigating, Member Kimble noted there 355 were qualifiers afterward in the redlined portion of the text. 356 Chair Boguszewski opined there were probably a number of properties in 357 Roseville already exceeding these proposed percentages; and asked staff what 358