Volume 2: Draft Gorst Planned Action Environmental Impact Statement

GORST PLANNED ACTION EIS | AFFECTED ENVIRONMENT, SIGNIFICANT IMPACTS, AND MITIGATION MEASURESdeveloped without these requirements and commercial areas would likely be redeveloped on the previouslydisturbed impervious surface without water quality treatment and would continue to impact floodplains and theshoreline. Incremental restoration and potential water quality treatment would occur on waters that are 303(d)listed. In addition, environmentally sensitive redevelopment in response to chronic flooding that would be likelyaddressed through emergency repairs or actions. Overall, Alternative 1 would have moderate impacts on waterresources in the UGA.Alternative 2Under the Alternative 2 (Gorst is a well-designed regional commercial center), the Watershed Characterization &Framework Plan would be adopted, a regional commercial center along the waterfront would be developed, andclustered Medium Density Residential development would occur on the mine site. Construction activitiesassociated with Alternative 2 could result in minor short-term impacts on water resources. Alternative 2 wouldallow a moderate increase in employment of 606 jobs and a more substantial increase in residents of 985 personsover the next 20 to30 years.The proposed Commercial Corridor development would accommodate new water quality treatment and likelyrestore segments of channelized streams as part of development requirements or incentives; however due togreater scrutiny of permits in floodplains and due to the listing of fish species, the developability of the Gorst Creekflood plain area for intensive commercial uses is expected to be challenging. The Medium Density Residential areaon the bluffs currently undeveloped but used as mining resources/borrow material would impact surface waterrunoff and alter natural hydrology. However, new designs and development would address potential for flooding,potential need for flow control, and treatment, minimizing impact on hydrology and water quality. In additiondevelopment and environmental retrofits along Gorst Creek could address of contributing outfalls. Estimates ofthe natural flow of the stream would need to be assessed to achieve proper hydraulic and aesthetic design. Thepotential for flood conditions and damage to surrounding property would also need to be determined andaddressed.Under Alternative 2, water resources would have additional protection from zero discharge of direct untreatedstormwater to both streams and the estuary and a goal of 100 percent on-site infiltration or detention. The Systemfor Urban Stormwater Treatment and Analysis Integration (SUSTAIN) model, which is described in Section 3.13.3Water, Wastewater, and Stormwater would be used to optimize and prioritize protection zones for waterresources.Overall, Alternative 2 would have a minor effect on water resources from short-term construction related impactsand moderate effects from long-term development continued development of high density commercial areasalong the shoreline. The long-term effects of the commercial development may be offset by implementation of theadopted Watershed Characterization & Framework Plan that would ensure stormwater in the watershed would betreated prior to discharge into sensitive waterways or critical areas. The Watershed Characterization & FrameworkPlan would have a beneficial effect on water resources.Alternative 3Under Alternative 3 (Gorst becomes a complete community), the Watershed Characterization & Framework Planwould be adopted, along with LID and stormwater standards. Similar to Alternative 2, construction activitiesassociated with Alternative 3 could result in minor short-term impacts on water resources. Similar to Alternative 2,adoption of the Watershed Characterization & Framework Plan would include a directive for protecting waterresource in the UGA. Under Alternative 3, compare to the other alternative would have less job growth at 333jobs, but the highest population growth at 1,082 persons over the next 20 to30 years.The proposed Gorst Mixed Use development would accommodate new water quality treatment and likely restoresegments of channelized streams as part of development requirements or incentives; however due to greaterDraft | June 2013 3-22