® The Final PUD plans shall be modified so that the stormwater runoff on the north and south <br />ends of the additional Capital Drive road width will be treated through either filtration or <br />mechanical treatment methods in compliance with the PIDS manual. <br />Private Roadway <br />The applicant has proposed to provide a filtration facility for the runoff of the east side of the <br />private street through the use of a filter strip and level spreaders. The applicant has stated that the <br />runoff on the north and south ends of the proposed private street will be too small to justify <br />installing on-site treatment methods and proposes to pay a higher rate of SDC's for the impervious <br />area created. This proposal is inconsistent with the requirements of EC 9.6792(3)(c), which requires <br />either infiltration or filtration facilities to treat the runoff of a proposed private street. For <br />compliance with this standard, the following condition is warranted: <br />® The Final PUD plans shall be modified so that the stormwater runoff on the north and south <br />ends of the proposed private street will be treated through a filtration facility in compliance <br />with the Stormwater Management Manual. <br />Individual Lots <br />The applicant has stated that individual lots will address flow control and water quality standards <br />when applying for building permits on a case by case basis. The applicant also suggests that <br />possible water quality mechanisms for the lots include: mechanical treatment, lined planters, rain <br />gardens, sand filters, or swales. Staff concurs that the water quality standards for the individual lots <br />will be addressed on a case by case basis at the time that each lot applies for a building permit. <br />EC 9.6793 Stormwater Flow Control <br />The site is located above elevation 500, triggering the need to meet flow control requirements. <br />Tables 1 and 2 of the applicant's Stormwater Management Plan and Drainage Study outline the <br />discharge locations and flow rates under existing conditions and proposed conditions, respectively. <br />Capital Drive <br />The applicant has proposed to use a number of underground storage facilities with orifices in order <br />to meet the flow control requirements of EC 9.6793. These underground detention tanks will direct <br />stormwater runoff to a location that mimics where runoff drains to under existing conditions. <br />According to Tables 1 and 2 of the applicant's Stormwater Management Plan and Drainage Study, <br />runoff from Capital Drive will discharge in three locations - Discharge Sites 1, 3, and 4. The <br />applicant has demonstrated that the proposed stormwater system receiving runoff from Capital <br />Drive will result in peak discharge rates that are less than (Discharge Sites 1 and 4) or equal to <br />(Discharge Site 3) pre-development conditions. Staff concurs that this is consistent with the <br />requirements set forth in EC 9.6793(3)(a). Site also notes that the facilities appear to be consistent <br />with EC 9.6793(3)(c), which requires that facilities be sited and designed according to the flow <br />control provisions and the facility design requirements set forth in the Stormwater Management <br />Manual. <br />Capital Hill PUD (PDT 17-1) Page 19 of 22 <br />