20201104-003a: Albert H. Ullrich Water Treatment Plant, Revision 2, SPC-03-0005C(R2) Staff Presentation — original pdf

Backup

Pamela Abee-Taulli Environmental Review Specialist Senior Development Services Department Radmon Rice Environmental Specialist Watershed Protection Department ULLRICH LOW SERVICE PUMP STATION ELECTRICAL FEED RENEWAL 3602 1/2 REDBUD TRL UNIT C SPC-03-0005C(R2) PROJECT LOCATION Site Location Austin ETJ Austin City Limits Edwards Aquifer Recharge Zone Edwards Aquifer Contributing Zone This product is for informational purposes and may not have been prepared for or be suitable for legal, engineering, or surveying purposes. It does not represent an on-the- ground survey and represents only the approximate relative location of property boundaries. This product has been produced by the Watershed Protection Department for the sole purpose of geographic reference. No warranty is made by the City of Austin regarding specific accuracy or completeness. 0510Miles[PROJECT LOCATION Lake Austin Westlake Hills Lady Bird Lake PROPERTY DATA •Water Supply Rural • Bee Creek, Little Bee Creek, and Lake Austin watersheds •Water Supply Suburban • Lady Bird Lake watershed •Drinking Water Protection Zone •Full Purpose Jurisdiction •Edwards Aquifer Recharge Zone •Wetland & Rimrock Critical Environmental Features •Council District 8 CONSTRAINTS Existing plant from 2003 CONSTRAINTS Steep slopes CONSTRAINTS Multiple Critical Water Quality Zones & Water Quality Transition Zones CWQZ WQTZ CONSTRAINTS Rimrock & Wetland CEFs Rimrock Wetlands BACKGROUND The plan proposes 6 projects to upgrade an existing City of Austin water treatment plant. The purpose is to improve operator and environmental safety by eliminating potential hazards and to upgrade miscellaneous plant processes to ensure the plant can reliably deliver drinking water. 6 PROJECTS In two phases. •Phase 2 •Phase 3 Phase 2 Phase 3 PHASE 2 1. Switchgear enclosure (#7) 2. Duct bank and access drive (#8) 8 7 1. Containment basin 3. Sludge changeover facility PHASE 3 2. Electric building and 4. 6-inch water line related duct banks 7 VARIANCE REQUESTS 1. Vary LDC 25-8-261 to allow development in the Critical Water Quality Zone, and by extension in the Water Quality Transition Zone of a Water Supply Rural watershed in the Edwards Aquifer Recharge Zone South [LDC 25-8-452]. 2. Vary LDC 25-8-281 to allow construction within a rimrock Critical Environmental Feature buffer. 3. Vary LDC 25-8-301 to allow construction of a driveway on a slope with a gradient of more than 15 percent. 4. Vary LDC 25-8-302(A)(1) to allow construction of a building on a slope with a gradient of more than 25 percent 7 VARIANCE REQUESTS 5. Vary LDC 25-8-341 to allow cut to sixteen (16) feet. 6. Vary LDC 25-8-342 to allow fill to twelve (12) feet. 7. Vary 25-8-453(D)(1)(a) to allow impervious cover to exceed the 20 percent limit for development in the uplands of a Water Supply Rural watershed ADDITIONAL INFORMATION & PHOTOS WETLAND PRESERVATION & MITIGATION • Applicant has redesigned driveway layout to avoid shoreline fringe wetland and to ensure that existing drainage is preserved to the maximum extent practicable. • Applicant has agreed to use current wave abatement criteria for shoreline stabilization to ensure drainage does not erode shoreline below culvert and has set outfall grade to preserve existing hydrology • Applicant will remove woody invasive species (such as Ligustrum, nandina, and photinia) within the wetland CEF buffer, • Applicant will remove garbage in the buffer • Applicant will plant 36 shade trees, 36 understory trees, 97 shrubs, and 280 grasses/forbs to restore disturbed areas and replace invasive species with native vegetation. • Applicant will install pole plantings within riprap along shoreline to revegetate the direct impacts to wetland where the culvert outfall meets the shoreline and will soil choke riprap above the waterline to help allow vegetation to grow. EXISTING CONDITIONS Riparian corridor within wetland buffer. INVASIVE SPECIES REMOVAL Invasive species removal will target species such as Photinia, Nandina, Ligustrum, and Chinese elm. DUCT BANK & ACCESS DRIVE Garbage removal, including old barge. Driveway impacts will generally follow an existing cleared pathway. RIMROCK CEF