Stormwater Development Standards. Maintenance Issues

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Assumptions Used to Estimate Maintenance Implications The following assumptions were used to estimate the maintenance implications of a water quality development standard in Eugene. • The City will maintain water quality facilities associated with multiple-parcel low-density residential developments except for maintenance of vegetation and debris/litter removal which will be conducted by the private entity. • The City will not maintain water quality facilities associated with high density residential, commercial, and industrial developments except as noted below for abatement. • The City will only maintain specific types of BMPs (e.g., swales,ponds, structural facilities, dry wells). • The City will not maintain site-planning BMPs (e.g., pervious pavement, roof drain disconnects, landscape planters). • Standards were applied to parcels>9,000i12. • The average development size is approximately 5 acres. • For purposes of estimating maintenance implications, it was assumed that 1/3 of new developments would construct ponds, 1/3 would construct swales, and 1/3 would construct structural facilities. • Fifteen percent of facilities constructed on HDR/Commercial/Industrial parcels would not be adequately maintained and would require some form of abatement by the City; a cost recovery mechanism would need to be created for this; no additional costs would be incurred by the City for this work. Using the current vacant lands information and the assumptions outlined above (i.e., parcels over 9,000 square feet, and an average development size of 5 acres), the number of developments for the two categories of land use was calculated (see Table 1). Table 1 Vacant Parcels within the UGB Land Use # of Parcels Total Area of Parcels # of Developments at ?9000 ft2 >_9000 ft2 (acres) build-out based on an average development size of 5 acres Low Density Residential 2,259 4,192 840 HDR/Com./Indus. 1,053 3,220 640 Other 148 291 NA Source: LCOG GIS Maintenance Requirements and Costs for BMPs Used to Estimate Implications Table 2 provides a summary of the potential range of maintenance activities and the required frequency for conducting those activities based on the current draft list of BMPs recommended for use within the City of Eugene. The table is broken down according to the various maintenance tasks that may potentially be required for each type of BMP. The tasks in the table include: e maintain vegetation(i.e., mow grass and remove invasive, overgrown or dead vegetation) • remove debris and litter I:\945042ne\task0400\memo8\Stormwater Policy Team Meeting.doc 3