Admin Order 58-12-14 - Laserfiche WebLink

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funding constraints), however, extending the piped system wholesale throughout RR -SC is not feasible nor is it the City's plan to do so. As shown on the figure, new development or infill development, if not located on an improved street that drains to a piped system, will need to assess the feasibility of constructing a piped system (including downstream connection and capacity constraints), and if not feasible or desirable, then the developer would need to select an approved alternative for managing stormwater on -site. Modifications to Figure 4 -11 will be made to reflect more clearly that on -site stormwater management (including volume controls) would be necessary under these circumstances. o Future situation, assuming new local "green street" design concepts are incorporated into the City's Local Street Plan (through a separate process). The local green street design concepts, which are envisioned to be alternatives to current local street standards, as proposed, assume that the linear rain gardens are sized for right of way runoff only, therefore development sites adjacent to a green streets would by necessity need to manage stormwater on -site (including volume controls). The green streets concepts could be employed on new local streets, or in a re- development situation. Permeable pavement options need to be considered [RR -81 Most street improvements will occur in response to development and most likely only in areas annexed by the City of Eugene. Permeable pavement has been used by the City on a pilot project basis, and is an accepted stormwater impervious surface reduction technique as long as it meets design criteria, but is not acceptable yet for use in the right of way. It should be acknowledged that such pavements accompany a higher construction cost and may be limited in their functionality without significant maintenance to prevent pore clogging. Permeable pavements are not recommended for sites with a likelihood of high oil and grease concentrations, which would include streets with a high number of average daily trips (> 1,000). Topic; Impervious Surface Area (ISA) RR -SC highest ISA percentages compared to other basins. [SC -31 The amount of impervious surface area (ISA) will increase as vacant or "underdeveloped" (meaning, not yet developed to Metro Plan designation and related densities) properties are developed. The basin plans estimate the future, or "buildout" ISA by assuming properties will be developed in accordance with the Metro Plan designations, and utilizes average ISA percentages by generalized land use categories, and the area of each land use category. The buildout ISA for the RR -SC basin is projected to be 50% (plan page 2 -12), an increase from the 2006 ISA of 37.5 %. The increase in ISA can be partly attributed to the relatively significant amount of vacant industrial area (326 acres as of 2006) within the basin. The estimated average RR -SC Stormwater Basin Plan Comments Pg. l l of 17