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Planning Commission Meeting Minutes – Wednesday, March 02, 2011 Page 16 grading plan had been submitted to the RCWD for their consideration and pending action 764 on March 23, 2011; and advised that the plan as prepared and submitted to the City 765 complied with requirements of the RCWD. 766 Related to references of Mr. Skaggs to the Hirschfield Study model and calculations, Mr. 767 Wicklund noted that as the Design Engineer, he was required to recognize the 768 requirements of the governing agencies within the project area, specifically the RCWD 769 and City of Roseville, and that was the reason for using that study for the proposal. Mr. 770 Wicklund opined that, at some point, as with all underground drainage plans, it would fail; 771 but advised that the engineering plans had provided for such an event through providing 772 for overland mitigation. 773 Mr. Wicklund noted that City Engineer Bloom had previously addressed the three (3) 774 wetland areas, and reviewed current drainage of the entire site inward to a local low 775 point. Mr. Wicklund advised that that the proposed grading plan provided for walkouts to 776 address grade changes off County Road C2 with the homes along that line having 777 service stubs already installed, and providing rear yard drainage and outlet by way of a 778 storm structure proposed to route into a drainage pone or wetland are. Mr. Wicklund 779 clarified that the area was recognized currently as a wetland, not a basin, and that 780 discharge directly into a wetland was allowed; and that the intent was only to route runoff 781 from rear yards that should address concerns of any additional pollutant loading. Mr. 782 Wicklund further clarified that such pollutant loading was not applicable to this area, was 783 not allowed, and not proposed. 784 Basin or Wetland Area North 785 Mr. Wicklund advised that, as a result of concerns raised during discussions with City 786 staff and the RCWD in not making the existing situation any worse than currently 787 experienced, the current development plan was created based on hydrocap modeling 788 with the area from the development property receiving storm water runoff from 1.5 acres; 789 and the current grading plan reducing that area by about ½ acre. Mr. Wicklund advised 790 that the developer also proposed minor impervious back yards for two of the units, further 791 reducing the catchment area, creating an overall reduction of the northwest basin, and 792 serving as an outlet for emergency overflow to the two other basins and pond. Mr. 793 Wicklund advised that all roadway runoff and yards captured and routed runoff to the 794 lower level, based on NERP criteria, with pretreatment in the basin prior to leaving the 795 site. Mr. Wicklund advised that the basins have a twenty (20) year life design for, with 796 everything contained and provided for within the development site. 797 Mr. Wicklund advised that if and when the system exceeded emergency events, an 798 overflow was provided between the homes to Lexington and past it into a wetland basin 799 across the street. Mr. Wicklund advised that, in the event of a considerably significant 800 event, additional protections had been provided for the homes based on freeboard 801 requirements higher than flood routing, as required by the City’s Subdivision Ordinance 802 and RCWD criteria. Mr. Wicklund noted that a lot of consideration had gone into grading 803 of the site to protect the homes, an important consideration for the developer as well as 804 to himself as the project engineer who’s reputation and design was under scrutiny now 805 and in the future. 806 Drainage to County Road C2 807 Mr. Wicklund advised that, to his knowledge, County Road C2 was higher than the 808 development property, with a good portion continuing to drain onto the site, which would 809 continue inward into the pond. 810 Drainage Concerns raised on Fernwood 811 Mr. Wicklund addressed drainage concerns of the property owner on Fernwood, advising 812 that the development was not adding any additional drainage to that area or restricting it. 813 Mr. Wicklund advised that he was aware of site drainage issues at that site, noting that 814 the grade changes across the property would serve to sufficiently route the drainage; and 815 expressed more concern if dealing with a flat site. 816