Admin Order 58-12-14 - Laserfiche WebLink

Home Browse Search

development but that capacity will need to be expanded to accommodate expected buildout scenarios. This possibility cries out for the use of development standards to avoid costly capital projects and to meet the goals of the neighborhoods for livable communities. The required use of low impact development standards (LIDS), pervious pavement in all roads, parking lots and driveways, and on -site storage and infiltration of all storm water would go a long way toward meeting the goals for water quality and flood control for new development without staggeringly expensive capital projects. Section 4: water quality evaluation The water quality evaluation for the RR/SC basin is based on incomplete data. All water quality collection sites were located in other basins and pollution estimates were extrapolated from measured levels of total suspended solids (TSS) even though "TSS has not been shown to directly relate to all other pollutants ". The estimated percentage increase in TSS loads (as a measure of pollution) for our basin, according to fig. 4 -2, is approximately 20% due to decommissioning of drywells, but 55% due to future development. These figures suggest that future development will be far more deleterious to our water quality than the effects of decommissioning drywells. However, this plan proposes no development standards for future development to address this situation. Conventional wisdom is that storm water directly injected to the water table via drywells pollutes the groundwater and that runoff directly piped to open waterways pollutes the surface water. We agree with those premises, but do not come to the same action plan for the basin based on the collected information. Instead of trying to collect and treat storm water on a municipal scale without adequate mechanical infrastructure and piping, a dispersed system of infiltration based on development standards that prioritize non - mechanical infiltration of storm water, on site infiltration, and post development flows not exceeding pre - development conditions would accomplish both capacity and quality issues. Greater dividends will be reaped through addressing future development impacts before they are manifest than creating oversized capital projects for decommissioning drywells that will also hopefully meet the needs for future capacity. Pollutant load estimates in this plan are built on an assumption that "new development would occur without the inclusion of water quality BMPs ". However, new stormwater standards require the pretreatment of storm water using BMPs in PUDs and subdivisions and the stormwater code updates should require the same of all new development. The idea that "decommissioning of all drywells would result in those discharges being transferred, untreated, to surface waters" presupposes that the water otherwise captured by drywells will be sent to open waterways. The water presently collected in drywells could surface infiltrate, as happens informally everywhere throughout our basin presently. If this were the case, it would not be transported to surface waters untreated, but treat itself in our native soils through infiltration. The proposed rain garden street designs and the accompanying assumption that streets in our area will be widened at the time of "improvement" have not been publicly discussed. Adopting a menu of options that change a 25 foot road bed to a 50 foot roadway without public process or input will create undue amounts of tension and dissent within our neighborhoods. Experiences with context sensitive street designs and the ongoing discussions around costs to the adjacent property owners for these "improvements" need to be rolled out to our community with adequate opportunity for participation, questioning, and processing by the residents. Ironically, all of the proposed street options create more impervious surface than presently exists. Are we not then creating the problem so that we can engineer a solution instead of valuing our narrower roadbeds which do an admirable job of transporting us and reducing runoff? Many communities around the world are adopting the use of narrower streets, shared streets and other more innovative solutions that encourage the use of alternative modes of transport while reducing the paving footprint, preserving urban canopy and vegetation, and improving neighborhood livability. Section 5: stormwater related natural resources As mentioned in the beginning, the top -tier priority for stormwater related natural resources in our basin would be the mapping, protection, and enhancement of all our "lesser" waterways that are not accounted for through Goal 5, WR, WP and WQ overlays. The progress of changes to and implementation of LID