Agenda Item 2c1_Update on AARC Master Plan — original pdf

Backup

Asian American Resource Center / Rutherford Campus Stormwater Improvements Preliminary Engineering Summary AARC Workgroup April, 14 2021 Lee Sherman, PE, Watershed Protection Department • • Greg Montes, Parks and Recreation Department Presenters: Agenda: • Summary of previously completed work • Introduction to this project • Project Origin • Project Elements • Project Schedule • Brief Q&A (please hold questions until the end) AARC Workgroup Meeting April 14, 2021 AARC Vision Plan • Vision Plan • Stakeholder process • Approval • WPD involvement Proposed Partnership Park Improvements • Partnership City of Austin (COA) project • Builds portions of the AARC Vision Plan • Add pedestrian bridge and other recreational amenities to conserve limited bond funds • Increases traffic and community use of historically under-utilized park area • Opportunity for water quality and drainage improvement Introduction Mission: CONCEPTUAL WATERSHED Protect lives, property and the environment of our community by reducing the impact of flooding, erosion and water pollution. Reduce the damaging effects of urbanization on Austin’s watersheds WHAT IS URBANIZATION? • Paving of land surfaces via construction of roadways, parking lots, buildings… • When rain falls, less water can soak into the ground • More water runs off to fill storm drains, creeks and rivers with more flow, faster Introduction 40% Evaporates 25% Evaporates AUSTIN IS URBAN… 10% Runoff RURAL 50% Infiltrates Groundwater URBAN 32% Infiltrates Groundwater 43% Runoff Introduction Flooding Exa mple: Shoal Creek near 15th Street Introduction Erosion Exa mpl es: Fort Branch Creek, Boggy Creek Introduction Water Quality Exa mple: McKi nney Falls (Williamson Creek) Benefits Infiltrates 1.7M gallons of water annually Water Quality • • More natural and cleaner water will flow to Little Walnut Creek • • Public education opportunity for water quality and stormwater management • Improved habitat for wildlife, pollinators, etc. Litter removal Flood • Resolves a flooding issue associated with the Rutherford campus AARC Vision Plan • Provides flood detention needed for AARC expansion • Provides the permanent water feature desired in the vision plan • Pedestrian bridge to connect the Rutherford parking to the AARC • Nature play areas and landscaping consistent with Vision Plan • Trails and habitat create connection to nature • Improve aesthetics of concrete channel AARC / Rutherford Tributary Watershed • Little Walnut Creek Watershed • Top 20 Overall WQ Problem Score • Nutrients, improved riparian habitat, stream stability 132-acres Multi-Functional Green Infrastructure Guiding Project Principles​ 1. Improve water quality, absorb storm events, and mitigate urban impacts to LWA​ Water Quality Improvements​ Infiltration Improvements​ 2. Encourage active recreation and wellness​ 3. Honor and represent the multitude of Asian identities the AARC serves​ 4. Preserve tree canopy and foster ecosystem health​ 5. Balance recreation and biodiversity goals with manageable maintenance​ Regional SCM Retrofit AARC Vision Plan • Gardens • Outdoor Reflection and Expression Rutherford Channel Overview of Proposed Features Proposed Solution: Wetland + Biofiltration Permanent water feature • • Wetland plantings to attract wildlife, WQ, and aesthetics • Predominately shallow (1’, with 6’ deep micropool) • “Mosquito Fish” and healthy habitat to control mosquitos • Biofiltration area • • Two shallow rain gardens along diversion channel (9” deep) Extended detention provides water quality and flood benefits UNDERDRAIN OUTLET = 584.5 INVERTED RISER = 583 MAIN POOL RAIN GARDEN 1 RAIN GARDEN 2 OVERFLOW= 590.5 WETLAND MAIN POOL = 586 UNDERDRAIN = 584.5 RISER = 583 GRAVEL = 584.5 - 583 BIOFILTRATION MEDIA = 586 – 584.5 WETLAND POND OVERFLOW POND INFLOW Rain Garden 2 Rain Garden 1 Diversion Channel Rutherford Channel Improvements • Remove concrete-lined sideslopes • Replace with stacked limestone blocks and vegetated tied concrete block matting • Retain existing concrete bottom Constraints • Existing trees • AARC/Rutherford Campus Parking • Wastewater and electric utilities • Flood conveyance Benefits • Create riparian habitat and natural aesthetic • Protect against erosion • Enhance infiltration and pollutant removal • Maintain flood conveyance Pedestrian Bridge • Address safety hazards with AARC members parking at Rutherford Campus • Educational opportunity with signage and Rutherford Channel restoration • Anticipating Subchapter E compliance for Site Plan – must increase connectivity Approximate Schedule • Preliminary engineering wrapping up in FY 21 • Stakeholder process remains • Coordination with AARC – input? • Design phase in FY22 • Permitting in FY23 • Construction in FY24 **Tentative - Subject to Change** Questions