(1)(j) C 9.6791 through EC 9.6797 regarding storm water flood control, quality, flow control for <br />headwaters area, oil control, source control, easements, and operation and maintenance. <br />EC 9.6791 Flood Control <br />In order to protect lives and properties from flood and drainage hazards, stormwater runoff from <br />development sites (as calculated utilizing the Rational Method and considering all developments <br />having received tentative or final plan approval) shall be discharged into existing stormwater flood <br />control facilities that have the capacity to handle the stormwater runoff; or, be retained or <br />detained onsite; or, discharged into a new stormwater flood control facility constructed by the <br />applicant. Proposed and required stormwater flood control facilities shall be designed and <br />constructed in compliance with code requirements. The applicant calculated the stormwater runoff <br />using software which utilizes the Santa Barbara Unit Hydrograph Method. This method is <br />acceptable and is considered an equivalent hydrological analysis to the Rational Method. <br />Per the applicant's Stormwater Management Plan and Drainage Study, dated March 3, 2017, and <br />stamped by Nathan Patterson, P.E., the stormwater treatment and management plan for the <br />development includes the widening of a public street, the construction of a private street, and <br />underground treatment and detention tanks. This report has identified five (5) existing points of <br />connection/discharge: (1) the eastern gutter line on Capital Drive, (2) Hendricks Park east of the <br />development, (3) a shallow channel north of the site, (4) the western gutter line on Capital Drive, <br />and (5) the adjacent neighboring properties to the west of Capital Drive. <br />The applicant has broken the proposed stormwater management up into three initial components: <br />(1) Capital Drive runoff, (2) private roadway runoff, and (3) individual lot runoff. The majority of <br />Capital Drive currently sheet flows to the west where intermittent curb exists. In areas where curb <br />does not exist, runoff drains to discharge point (5), which are the neighboring properties to the <br />west of Capital Drive. <br />Capital Drive <br />The applicant has proposed to construct a flush curb on the west side of Capital Drive in the areas <br />where a functioning curb currently does not exist. The proposal for a flush curb is consistent with <br />existing drainage patterns. The applicant is proposing to reconstruct Capital Drive to City of Eugene <br />local street standards, which includes constructing the road to a width of 21 feet. The road is being <br />proposed to be constructed in a fashion that mimics existing drainage patterns and quantities, with <br />any additional street width draining to the east gutter. There is a high point in Capital Drive at <br />approximately the middle of the site. Runoff south of the high point on the east side of Capital <br />Drive will be collected into catch basins and directed to a mechanical treatment device near the <br />southern intersection with the private roadway. The runoff will then exit the underground system <br />via a bubbler and continue down the curb line at a rate less than or equal to existing rates. Runoff <br />north of the high point on the east side of Capital Drive will be collected into a proposed catch <br />basin and underground detention tank system that will discharge into an existing drainage ditch <br />north of the site. Runoff on the west side of Capital Drive will drain at rates and locations that <br />match existing conditions - either the western gutter line or the adjacent neighboring properties to <br />the west. <br />Capital Hill PUD (PDT 17-1) Page 17 of 22 <br />