Hearings Official Decision - Laserfiche WebLink

Private Roadway The applicant has proposed to provide a filtration facility for the runoff of the east side of the private street through the use of a filter strip and level spreaders. The applicant has stated that the runoff on the north and south ends of the proposed private street will be too small to justify installing on-site treatment methods and proposes to pay a higher rate of system development charges (SDC) for the impervious area created. This proposal is inconsistent with EC 9.6792(3)(c), which requires either infiltration or filtration facilities to treat the runoff of a proposed private 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 proposed private street will be treated through a filtration facility in compliance with the Stormwater Management Manual. Individual Lots The applicant has stated that individual lots will address flow control and water quality standards when applying for building permits on a case by case basis. The applicant also suggests that possible water quality mechanisms for the lots include: mechanical treatment, lined planters, rain gardens, sand filters, or swales. The water quality standards for the individual lots will be addressed on a case by case basis at the time that each lot applies for a building permit. Based on these findings, and with the recommended conditions of approval, this standard is met. EC 9.6793 Stormwater Flow Control (Headwaters) Finding: The subject property is located above elevation 500, triggering the need to meet flow control requirements. Tables 1 and 2 of the applicant's Stormwater Management Plan and Drainage Study outline the discharge locations and flow rates under both existing conditions and proposed conditions. The hearings official adopts the findings of the Staff Report, which establish compliance with the EC 9.6793 Stormwater Flood Control (Headwaters) standards, as follows: Capital Drive The applicant has proposed to use a number of underground storage facilities with orifices in order to meet the flow control requirements of EC 9.6793. These underground detention tanks will direct stormwater runoff to a location that mimics where runoff drains to under existing conditions. As depicted on Tables 1 and 2 of the applicant's Stormwater Management Plan and Drainage Study, runoff from Capital Drive will discharge in three locations - Discharge Sites 1, 3, and 4. The applicant has demonstrated that the proposed stormwater system receiving runoff from Capital Drive will result in peak discharge rates that are less than (Discharge Sites 1 and 4) or equal to (Discharge Site 3) pre-development conditions, consistent with the requirements set forth in EC 9.6793(3)(a). The facilities appear to be consistent with EC 9.6793(3)(c), which requires that facilities be sited and designed according to the flow control provisions and the facility design requirements set forth in the Stormwater Management Manual. Private Roadway Hearings Official Decision (PDT 17-1) 74