B1-3: Flats on Shady lane Chapter 26 Rev 3 — original pdf

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Temporary and Permanent Use of Parkland at Govalle Neighborhood Park Flats on Shady Multi-Family Development 1125 Shady Lane SP-2020-0368C Boggy Creek Watershed Flats on Shady Multi-Family Development Project Area • Approximately 7.93-acre multi-family development • Adjacent to Govalle Neighborhood Park and Southern Walnut Creek Trail • Existing and proposed site drains to Boggy Creek • Located in Council District 3 Regional Stormwater Management Program (RSMP) • Located in lower end of Boggy Creek watershed • Site proposed to drain directly to Boggy Creek • Timing of flow from site versus Boggy Creek watershed − Release preferable to detention − Water quality and 2-year detention provided Flats on Shady Site Plan Storm Drain Outfall for Multi-Family Project • Need − Provide storm drainage for proposed multi-family development • Description − Approximately 156 feet of 60-inch storm drain and one manhole in Govalle Neighborhood Park and Southern Walnut Creek Trail parkland • Schedule − Best case: 60 days within the August to October 2022 timeframe − Worst case: 60 days within the January to March 2024 timeframe • Easement Request − Temporary use: 4,655 sq. ft. − Permanent use: 6,205 sq. ft. Flats on Shady Project Drainage Considerations 1. Drain to Storm Drain in Shady Lane (Not Viable) • Against slope of site • System in Shady lacks capacity 2. Storm Drain Through Park Land to Boggy Tributary • Avoid USACE coordination • Significant tree impacts • Longer path 3. Detain and Release Overland to Boggy • Pumping required • Overland flows through parkland 4. Storm Drain Through Parkland to Boggy • Shortest path • Requires USACE coordination • Minimizes parkland impact 1 2 4 3 Design Elements to Minimize Maintenance Needs • Gasketed and wrapped pipe joints • Controlled Low Strength Material (CLSM) bedding • Access manhole on property • Access manhole in parkland Means of Construction • Open cut construction proposed • Boring construction evaluated − Much higher cost − Challenges due to size of pipe bore pits − Additional impacts from − Trail likely would need to be closed • Trail re-route Maintenance Access Considerations Through Govalle Park 1. 2. Walnut Creek Trail 3. New Trail and Bridge 4. 5. Through Site Boggy Creek 4 1 3 2 5 Dedicated Access Easement Request for Committee Action • Make a recommendation to City Council for approval of Permanent Use and Temporary Use not to exceed 60 Days of parkland located at Govalle Neighborhood Park (5200 Bolm Road). • Total Mitigation is $67,818. − Permanent Drainage Use: $67,014 − Temporary Working Space: $804 Watershed Protection Sponsor Contact Karl McArthur, PE, CFM, Supervising Engineer Karl.McArthur@austintexas.gov 512-974-9126 Developer Team Contact (Drenner Group, PC) David Anderson, PE, D.WER, CFM, CPESC, Director of Land Use & Entitlements danderson@drennergroup.com 512-807-2908 12