CITY COUNTY DRAIN FLOOD MITIGATION PROJECT OUTLINE 1 What - - PowerPoint PPT Presentation

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CITY COUNTY DRAIN FLOOD MITIGATION PROJECT OUTLINE 1 What - - PowerPoint PPT Presentation

Nov 15, 2023 45 likes •338 views

CITY COUNTY DRAIN FLOOD MITIGATION PROJECT OUTLINE 1 What Happened in 2018? 2 Overview of the Project 3 Challenges 4 Solutions 5 Construction Photos 2 Project Area Downtown Billings City County Drain CCD Project Area South Billings

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CITY COUNTY DRAIN FLOOD MITIGATION PROJECT

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OUTLINE

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1 What Happened in 2018? 2 Overview of the Project 3 Challenges 4 Solutions 5 Construction Photos

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Project Area

City County Drain

King Avenue Interchange South Billings Boulevard Interchange CCD Project Area Downtown Billings

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  • Significant Runoff in the Yellowstone River

− Prolonged flows greater than 40,000 cfs (2-Year) − Erosion along the North Bank of the River

  • Intense Rainstorm Occurring in Billings

− Significant flows down City County Drain

What Happened in 2018?

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2018 Conditions 2019 Conditions

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Abrupt Change in Backwater Conditions

City County Drain 2123.52 2131.02 2133.28 7.5’ 2.3’ Island Provides 2-Year Protection Bank Provides 10-Year Protection

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Challenges

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1 Schedule – Provide Protection By Spring 2019 2 Conflicting Objectives A Prevent Backwater from Yellowstone River B Maintain Capacity in CCD for Storm Runoff

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Alternative #1

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NOT SELECTED

  • Right of Way Costs
  • Schedule
  • Grey Eagle Ditch

Crossing

Reconstruct New Drainage Ditch

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Alternative #2

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NOT SELECTED

  • Cost
  • Schedule
  • Limited Room

New RCB Storm Drain

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Recommended Solution

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Flood Control Gate Inlet Structure

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  • Typical Design-Bid-Build Contract would not have met the schedule
  • City of Billings requested proposals from Construction Contractors

− COP Construction was selected

  • Benefits

− COP Construction provided Value Engineering recommendations for 30% Design − Early procurement of pipe allowed construction to begin before final design was completed − Contractor paid T&M plus an agreed-upon markup, with a maximum guaranteed price. − Allowed for efficient processing of minor field changes.

Accelerate Schedule

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Construction Manager / General Contractor Contract (CMGC)

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  • All permits were in hand for February 2019 Start

− 2nd Coldest February in Billings History − 29.4” of Snow (3rd Snowiest February in Billings)

  • Construction

− 4,250 LF 48” RCP Pipeline

− Started 3-4-2019 and finished 4-15-2019

− Crest Gate Installed on 7-16-2019 (temporary sheet piling for water control) − Project Completed on 8-15-2019

Construction

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48-inch RCP Pipeline

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Yellowstone Outlet Structure

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Pipeline Inlet Structure

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Fish Bypass

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Flood Control Crest Gate

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Gate Automation

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Gate Automation – Typical Position

Yellowstone River WSEL Baseflow in CCD Through 48-inch Pipe

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Gate Automation – Runoff From CCD

Yellowstone River WSEL Baseflow Gate Lays Down Providing additional flow capacity for stormwater runoff

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Gate Automation – Return to Typical Position

Yellowstone River WSEL Baseflow in CCD Through 48-inch Pipe

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Frozen Ground & Compaction

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Groundwater

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Backwater from Yellowstone River

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City County Drain Stormwater Flows

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  • Protected Upstream Residence from 2019 Runoff Condition
  • Project came within the $2.85 million budget
  • Gate Automation Provided Limited Work for the City Maintenance Staff

Project is Completed

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Questions?