2009/03/25 Council Agenda Packet

Planning Commission Meeting January 22, 2008 Page 3 Alternative 2 provides for approximately 700,000 square feet of office space on the Simpson Pad; approximately 700,000 square feet of commercial space on Landfill Site; approximately 200,000 square feet of commercial on Eclipse Mill site; and associated public amenities. Alternative 2 (Option 2) provides for office buildings on the Simpson Pad changed to higher profile, but less quantity; All other aspects of proposed development unchanged. The EIS addresses earth resources, air, surface water and channel migration, storm water, plants and animals, energy and natural resources, visual, parks and open space, transportation, public services and utilities, environmental health and hazardous materials, and noise. He presented a brief overview of the issues and how the impacts were addressed in the EIS. Earth Resources Filling and Grading -Best management practices Seismic Hazards (settlement, lateral movement and liquefaction) -All parcels: pre-loading; Simpson site: Stone columns and/or pile foundations; and landfill site: Pile foundations Erosion Hazards- BMPs and erosion control measures Air Minor, localized impacts to/from construction - management practices targeted at potential impacts Other minor potential odor impacts-design and compliance with applicable regulations Surfacewater and channel migration Impacts from 100-year and 500-year Floods - Developed areas will be raised more than 2 feet above 100-year flood level and above 500-year level. (Most of the development areas are already above these levels.) Channel Erosion Issues: minor local impacts - Maximum shear stress values calculated for the 100-year and 500-year floods demonstrate that this reach of river is fairly low energy, with little erosive potential applied to the streambed or stream banks. Essentially, this can be interpreted as a measure of high channel stability through the reach. Channel Migration • Forest Practices Board Manual approach using 1869 General Land Office (GLO) map and aerial photographs from 1938, 1967 and 2002 clearly indicates that the basic channel pattern or configuration has not changed appreciable, and there has been no observable channel migration • Minor erosion observed (absent channel migration) will have no impact on activities set back and separated from the bank and levees by additional fill and development Future Impacts from Climate Change • Proposed elevations are higher than worst case increase in sea level projected • Flood timing would likely change to a single large annual event rather than a dual peak (due to loss of snow pack) Stormwater Stormwater during construction - Use BMPs including sequencing, filters, compost berms, etc. Stormwater from Development- Compliance with 2005 Ecology Manual Simpson site methods—will infiltrate as much stormwater as possible and utilize it into green areas and also utilize the stormwater to enhance into surrounding wetland areas. Landfill/Tire Fire site methods—Landfill capping limits options (no infiltration); most goes to sewer system; clean storm overflow to River.