Hearings Official Decision - Laserfiche WebLink

is for runoff along the northern portion of the private roadway. This runoff will be collected into a series of underground storage tanks and discharged into an existing drainage ditch north of the proposed development site. Individual Lots For the lots bound by the new roadway improvements, upon treatment and flow control, drainage disposal will discharge onto the new roadways. For the lots draining away from the roadway to the east, disposal will be into level spreaders directed toward the existing park land to the east or north. These locations are consistent with existing drainage patterns. The proposed system has been designed so that discharge will occur at locations that mimic existing conditions and at rates that are less than or equal to existing rates. The results from infiltration testing confirms that the soils (Hydrologic Groups C and D) mapped at this site are not appropriate for on-site infiltration, which is why the applicant has proposed a series of underground mechanical forms of collection, detention, treatment, and discharge. Staff confirms that the proposed detention system demonstrates conceptual compliance with this standard and EC 9.6791(3)(b)(2), subject to a more detailed review for compliance with applicable standards during subsequent permit reviews. Based on these findings, this standard is met and will be further reviewed at the time of development. EC 9.6792 Stormwater Quality Finding: The hearings official adopts the following findings and conditions of the Staff Report, which establish compliance with the EC 9.6792 Stormwater Quality standards, subject to compliance with the specified conditions: In order to reduce runoff pollution and mitigate the volume, duration, time of concentration, and rate of stormwater runoff from the development, the applicant must select, size, and locate stormwater quality facilities from the Stormwater Management Manual to treat the stormwater runoff from the proposed development. As noted previously, the application includes the widening of an existing public street as well as the construction of a private street. Capital Drive The applicant has stated that the additional road widening of Capital Drive is too small to justify the cost of water quality treatment, and therefore has proposed no treatment facilities for this portion of the project. This is inconsistent with EC 9.6792(3)(b), which requires infiltration, filtration, or mechanical facilities to treat the runoff of a proposed public street. For compliance with this standard, the following condition is warranted: The final plans shall be modified so that the stormwater runoff on the north and south ends of the additional Capital Drive road width will be treated through either filtration or mechanical treatment methods in compliance with the Public Improvement Design Standards manual. Hearings Official Decision (PDT 17-1) 73