<br />Ordinance -- Page 4 of 10 <br />(a) For land use applications not proposing the construction of a public or private street or <br />shared driveway, the applicant shall submit a site development plan that delineates the <br />following conditions existing on the development site <br /> <br />(a) Stormwater quality facilities for water quality treatment shall be selected from and <br />sited, designed, and constructed according to the Stormwater Management Manual. <br />The selected stormwater quality facilities shall treat all stormwater runoff from all new <br />or replaced impervious surface areas, or an equivalent on-site area, that will result from <br />the water quality design storm. <br /> <br />(b) Stormwater quality facilities shall be selected based on the following priority order. <br /> <br />1. Infiltration shall be utilized for treatment of the water quality design storm <br />runoff unless one of the following site conditions exist: <br /> <br />1a. Infiltration rates are less than 2 0.6 inches per hour; <br /> <br />2b. Bedrock is less than 5 feet below the ground surface; <br /> <br />3c. Groundwater elevations are less than 6 feet below the ground surface; or, <br /> <br />4d. Ground surface slopes are greater than 10%. <br /> <br />2. If any of the site conditions listed in subsection (3)(b)1 exist, extended filtration <br />(filtration through natural or engineered media) shall be utilized to treat the water <br />quality design storm runoff from the impervious surface areas unless: <br /> <br />a. The applicant submits a report that includes a site plan of the proposed <br />development and the required sizing of the stormwater quality facility based <br />upon the water quality design storm requirement showing that the <br />development site has insufficient land area to construct an infiltration or <br />extended filtration facility to treat the water quality design storm runoff <br />without reducing the size of the proposed development; and <br /> <br />b. The proposed development is otherwise consistent with all other <br />applicable lot and development standards. <br /> <br />(c) An applicant that is not required to use an infiltration or filtration system for any of <br />the reasons stated in (a), (b), or (d) of this section will be subject to the Low Impact <br />Development component of the City’s system development charge improvement fee due <br />to the reliance on an off-site system. In that case, the City’s system development charge <br />methodologies may include a stormwater system development charge credit for an <br />approved on-site mechanical treatment facility. <br /> <br />(b) For land use applications proposing the construction of a public street, stormwater <br />quality facilities to treat the stormwater runoff from the proposed public street shall be <br />Commented [DS6]: Testimony raised concern regarding <br />the use of “shall be,” requiring a system identified in the <br />Stormwater Management Manual, specifically with <br />concern that this will limit the ability to design hybrid <br />facilities. StaƯ response: The Stormwater Management <br />Manual does allow for hybrid facility designs without the <br />need for an Adjustment Review process. Note, <br />alternatives to the facility types in the Stormwater <br />Management Manual can be proposed through an <br />adjustment review process. This is no change to the <br />current practices. <br />Commented [DS7]: Testimony raised concern regarding <br />lowering the infiltration rate that requires an infiltration <br />facilities for the water quality design storm from the <br />current 2 inches per hour down to 0.6 inches per hour. <br />StaƯ recommend the 0.6 inches per hour threshold to <br />promote infiltration per the NPDES permit. The testimony <br />is concerned that this is likely to require larger facilities <br />than under the current code. While this may be true, this <br />rate is the industry standard to meet the requirements of <br />the City’s NPDES permit. <br />Commented [DS8]: Testimony raised concerns that the <br />code could be requiring extended filtration facilities in an <br />area where the topography could make such facilities ill <br />advised. To address this concern, staƯ have included a <br />possible adjustment to the requirement for filtration. See <br />newly proposed EC 9.8030(24)(c). <br />Commented [DS9]: Testimony raised questions <br />regarding how “insuƯicient land area” is determined. <br />StaƯ response: This is specified in subsections 2.a. and <br />b. This language is very similar to the current code <br />language that has been in place since 2014 and under <br />which there has been no interpretive issue.