20201104-002a: Country Club Creek West at Roy G. Guerrero Park Update — original pdf

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Country Club Creek West at Roy G Guerrero Park Environmental Commission November 4, 2020 Janna Renfro, P.E. Project Sponsor Watershed Protection Department 1 Project Area Roy G. Guerrero  Colorado River Metro Park • 363 acres • Constructed  drainage channel  – Country Club  West • Original drainage  • channel – Country Club East Improvements  constructed in  2010 2 Erosion Damage • 2015 Floods  • Severe erosion  created a shorter  path to the river. • Pedestrian bridge  collapsed • May 2015 ‐ December 2017:  Erosion damaged  ~1500 feet (5 acres)  of drainage channel • 100s of trees lost • 2500 dump truck  loads of sand and soil  (~37,000 cubic yards) 3 Permanent  Solution • ~2,000 linear feet of  channel stabilization • Three concrete “drop  structures” • Natural channel  between structures • Bridge over middle  structure above 500‐ year flood elevation 4 Temporary Repairs • Project No. 1 • 2017 • Protect Ballfields Interim Project № 1 Permanent Project 5 Temporary Repairs • Project No. 2: • 2018 • Stop headcut from  moving upstream  Interim Project № 2 Permanent Project 6 2019 – 2020 Update Items • Erosion Progresses • Three New Temporary Repair Projects • Emergency Affidavit • 60% Design Deliverable • Updated Construction Cost Estimate • Schedule 7 Temporary Repairs • Project No. 3: • 2019‐20 • Protect 54” Active  Wastewater Line Interim Project № 3 Permanent Project 8 Temporary Repairs • Project No. 4: • 2020 • Protect Park Road Interim Project № 4 Permanent Project 9 Temporary Repairs • Project No. 5: • 2020 • Repair failed  temporary headcut stabilization Interim Project № 5 Permanent Project 10 Emergency Affidavit • Summer 2019:  ◦ New LiDAR ◦ Progression of erosion ◦ Continuing vulnerability of temporary repairs  ◦ Need for additional temporary measures • Fall 2019 ◦ Emergency affidavit ◦ Expedited bid process 11 60% Design & Cost Estimate • 60% Design – Received Spring 2020 • Construction Cost Estimate — $25M ◦ Why?   ◦ How? 12 Project Schedule Complete Design Bid Begin Construction Complete Construction 13 14 Trail Connectivity 15 Physical Modeling • Conditions are  unique and  challenging • High consequence of  failure requires more  certainty • Improve drop  structure design • Determine stable  channel  configuration 16 Model Findings 9 Revise channel alignment  9 Maximize width 9 Structure modifications Do nothing? • Headcut will continue to move upstream. • High confidence of threats upstream • Increasingly expensive project Wickersham ‐ BEFORE Current  Headcut Location Wickersham ‐ AFTER 18