2015-12-02_PC_Minutes - Laserfiche WebLink

Home

Planning Commission MeetingPage of 12 ? Mr. Lloyd briefly reviewed the tree preservation reviewed by the Citys tree consultant Mark ? Rehder, S & S Tree Service, with monitoring continuing as the project proceeded. Specific to Park Dedication, Mr. Lloyd reported that with two additional lots, the Parks & Recreation Commission had determined cash in lieu of land. As noted in the staff report (line 99), Mr. Lloyd advised that the Development review Committee (DRC) provided several comments for recommendation, and highlighted the need for including Item D (lines 121 123) to ensure a homeowners association be a condition of approval to ensure ? longterm private street and stormwater infrastructure maintenance remains intact. ? Discussion Chair Boguszewski asked for clarification if the additional flow capacity for Acorn Road was new or had been there before; and whether the City Engineer had an estimate of the total flow pulled toward Acorn Road and away from that southwest corner. Mr. Lloyd responded that the routing is new for this iteration of the Oak Acres Development proposal, as in the past runoff was routed to rain gardens at the southwest corner of the proposed development. Mr. Lloyd reported that the City Engineer had not specifically isolated the total flow from the southwest corner now proposed to be directed to Acorn Road stormwater infrastructure, but the difference in volume of stormwater leaving the southwest corner of this proposal versus previous iterations reduced that runoff by approximately 58% for a 100 year rain event calculation. At the request of Chair Boguszewski, Mr. Lloyd clarified that (as noted in line 106 of the staff report) overall flow was actually reduced by approximately 82% with this latest development proposal, and reduced 58% from the previous iteration. As noted by Chair Boguszewski, this provided the neighborhood with an approximate 82% improvement in stormwater flow compared to current runoff flowing from the property. On line 113, Chair Boguszewski questioned the subjective term aggressive proposal” and asked ? Mr. Lloyd to describe what was intended for a homeowners association and their financial burden. Mr. Lloyd advised that that term originated with review by the Citys Public Works Department, and ? opined the proposal was certainly aggressive in the sense it provided many places for water infiltration for rate control, and significantly reduces current rates and volumes. However, Mr. Lloyd noted there was also a cost component and need to make sure funding remained available long ? term to address those many maintenance components and their complexities. Member Murphy noted that water runoff from the subject site to neighboring properties had continued to be of great concern in past iterations, and asked staff if this iteration was implemented as designed indicated only 18 gallons of stormwater runoff. Member Murphy asked if there would be any cost to the city for connecting and diverting stormwater flow to the Acorn Road system or if it would borne entirely by the developer. Mr. Lloyd clarified that runoff was measured by cubic feet per second, not gallon, and confirmed that 100 year rain event model numbers indicated that would be the case and as compared with typical rain events where stormwater runoff should easily be addressed through infiltration of one mode or another. Mr. Lloyd confirmed that the cost to divert stormwater flow to the Acorn Road infrastructure would be at the cost of the developer to implement. Member Murphy asked staff for a comparison with this latest tree removal plan with that of the most recent past iteration. Mr. Lloyd advised that staff didnt perform a comparison between previous and this latest proposal. ? However, Mr. Lloyd advised that the arborists review indicated there would probably be no ? replacement required with the trees proposed for removal and fewer structures with this development proposal and based on updated tree inventory information (e.g. dead trees listed in the previous inventory versus their size and condition, and review by diameter breast height, of DBH, in this review). Regarding staff comments and review by the DRC related to stormwater flow toward Acorn Road, Member Bull sought clarification of the actual flow as displayed on the grading plan. Member Bull expressed concern that the proposed infiltration basins may not be empty before the next rain event occurs, causing overland flow issues. Member Bull questioned longterm maintenance of the ? basins or how the city would address that maintenance. Mr. Lloyd reviewed the underground connections, overland flow, and reduced flow percentages, file:///R:/CommDev/PLANNING_AND_ZONING/PLANNING_COMMISSION/Minutes/...4/11/2016