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1. If selecting a filtration treatment facility, the applicant shall submit a report that demonstrates at least one of the following development site conditions exist: a. Infiltration rates are less than 2 inches per hour; b. Bedrock is less than 5 feet below the ground surface; c. Groundwater elevations are less than 6 feet; or, d. Ground surface slopes are greater than 10% 2. If selecting off-site stormwater quality management by contributing to the public off-site stormwater quality facilities, through payment of a higher stormwater system development charge adopted as part of the City's system development charge methodology, the applicant shall submit a report that demonstrates there is insufficient land area to construct an approved infiltration or filtration facility by setting forth the required size of the smallest infiltration or filtration facility needed for the development's impervious surface area and a site plan demonstrating that an approved infiltration or filtration facility cannot be located on the development site without reducing the size of the proposed development which is otherwise consistent with all other applicable lot and development standards. The proposed water quality treatment will be accomplished using a combination of infiltration planter boxes and filtration planter boxes. All of the impervious surfaces will be treated prior to discharge to the public system. Filtration planter boxes will be used to treat runoff f •om the roof. Regardless of the soil infiltration capacity, the planter boxes around the building are required to have an impervious liner due to the fact that they are located less than 10 feet fi-om the building. Infiltration planter boxes will be located around the perimeter of the parking area. Storm drainage will enter the planter boxes via curb cuts. These planter boxes will be two feet wide so that a minimum five foot setback is maintained from the property line. As noted previously, there is not sufficient area available to size these infiltration planters to accommodate the flood control volume required by the Stormwater Management Manual based on the assumed infiltration rate allowed by the Manual. As such, these infiltration planters will still require the developer to pay System Development Charges based on the rates for filtration planters, but will minimize the amount of stormwater being discharged to the public system. (e) The selected stormwater quality facilities shall treat all stormwater runoff from all new or replaced impervious surface areas, or an equivalent onsite area, that will result from the water quality design storm except that the selected the stormwater quality facility does not need to treat the stormwater runoff from new or replaced impervious surface that is 500 sq. feet or less and does not gravity-feed into the selected treatment facility. All impervious surfaces will be treated by the proposed stormwater system prior to discharge. (f) All stormwater quality facilities shall be sited, designed and constructed according to the water quality provisions and the facility design requirements set forth in the Stormwater Management Manual. All facilities have been located and sized based on the criteria in the Stormwater Management Manual. Calculation details are provided in the Stormwater Report, (Attachment L). As noted previously, infiltration planters maintain the required 5 foot separation f -om property lines. Filtration planters are located within 10 feet of the building and will require a waterproof liner. Eugene Towneplace Suites Page 32 April 4, 2016