Water Tank Rehabilitation for a Small Community

Presented By:

Ajay Kashi

Gannett Fleming Inc.

Water Tank Rehabilitation for a Small Community

TOWN OF BOWIE LOCATION MAPTOWN OF BOWIE LOCATION MAP

Water Tank Rehabilitation for a Small Community

PRESENTATION OVERVIEW Introduction Objective Project Funding Project Execution Lessons Learned

Water Tank Rehabilitation for a Small Community

INTRODUCTION History & Background

Approximately 70 years old Privately owned until 1985 Currently Maintained & Operated by BWID

Existing Water System Two (2) Groundwater Wells One (1) 150,000 Gallon Storage Tank Two (2) Hydro-pneumatic Tanks 2”, 4” and 6” Waterlines

Water Tank Rehabilitation for a Small Community

CONDITION OF THE TANK Exterior

Water Tank Rehabilitation for a Small Community

CONDITION OF THE TANK Interior

Water Tank Rehabilitation for a Small Community

PROJECT OBJECTIVE Restore Health and Safety

Replace or Rehabilitate the Tank Eliminate Rust and Deterioration Safe Environment for the Operators

Water Tank Rehabilitation for a Small Community

PROJECT FUNDING Completely Funded by USDA-RD (United States

Department of Agriculture - Rural Development) Gannett Fleming Inc, was selected as Consulting

Engineers to prepare a Preliminary Engineering Report (PER)

Water Tank Rehabilitation for a Small Community

PER (Comprehensive Report) Thorough Site Investigation Discussions with the BWID to identify

Operations and Maintenance issues Financial Information Alternative Improvements Considered Engineer’s Estimate of the Costs Alternative Improvement Recommendation Rural Development Approved Funding for Tank

Rehabilitation

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Construction Phase Services

Gannett Fleming provided

Project Representative

Services during Rehabilitation

Bypass Piping Modifications

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Guardrail Installation according to OSHA

Standards

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Tank Interior Cleaning

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Interior after Blasting

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Interior Inspection and Tank Floor Cost Evaluation

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Tank Floor Installation

Water Tank Rehabilitation for a Small Community

VACUUM TEST Welded Joints were tested for

air-tightness

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Interior Inspection Prior to Coating

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Epoxy based NSF 61 Approved

Interior Coating Three Coat System

Prime Coat (4 mils) Intermediate Coat (5 mils) Finish Coat (5 mils)

Welds, seams and irregularsurfaces were coated with brush

Smooth surfaces were coatedwith rollers

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION NSF 61 Approved Interior Coating

Sealant (Polyurethane Elastomeric Adhesive) for Roof Plate Lap Joints

Water Tank Rehabilitation for a Small Community

Tests for Interior Coating System Dry Film Thickness Test Holiday Test (Low Voltage Wet Sponge Test)

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Exterior Coating (Epoxy Based)

Pressure Washed According

to SSPC Standards Two Coat System

Prime and Finish Coat Total System Thickness

of 5 – 8 mils (DFT)

Water Tank Rehabilitation for a Small Community

PROJECT EXECUTION Disinfection

AWWA C652 Stds and ADEQ Bulletin No. 8 Interior Pressure Washed prior to Disinfection 200 mg/l Available Chlorine was Sprayed on the

Interior Surface Water allowed inside after 30 minutes of

Disinfectant Retention Time

Testing BAC-T for Coliform Organisms

Water Tank Rehabilitation for a Small Community

LESSONS LEARNED Thorough Tank Inspection is Critical Prior to start of

the Project Thorough Interior Surface Inspection after Blasting is

Essential Confined Space Entry

Entry Permit and Procedures were required for the Contractor and Site Inspectors according to OSHA

Water Tank Rehabilitation for a Small Community

ACKNOWLEDGEMENT USDA Rural Development Bowie Water Improvement District, Town of Bowie

Water Tank Rehabilitation for a Small Community

SAND BLASTING

• Dry Abrasive Blasting• The abrasive media was Silica Sand coated with

Resins to prevent creation of dust during blasting process.

• Abrasive Media Particle size range between 10 micrometer to 150 micrometers.

Vessel containing abrasive media

Power supply & Air-Compressor

From the Vessel media is pressurized through a pipe into a hand held nozzle in the end

HOLIDAY TEST INFORMATION

• For Holiday Tests, the Detector is set at 700 Micro-Amps (mA) to set off an audible indicator.

• Low Voltage Holiday Tests are conducted for metal surfaces which have coatings of 20 mils or less.

• High Voltage Holiday Tests are conducted for metal surfaces which have coatings of 20 mils or greater.

DISINFECTION

• Overflow piping need not be disinfected according to AWWA C652 standards for “Disinfection of Water Facilities.”

• Required Chlorine Residual in water according to AWWA C652 Standards is 2 mg/l.

USDA-RD FUNDING CRITERIA FOR BOWIE

• Bowie is a very poor rural community• The funding criteria for a Rural Community is based

on its Median Household Income (MHI). • If the MHI for a Rural Community is LESS THAN 50%

of the MHI for the State, that Rural Community is qualified for a 100% Grant by the USDA-RD.

• MHI data can be obtained from the Department of Labor Statistics.

ANOTHER OPTION FOR FIXING THE TANK FLOOR

• Apply 50 mils of a Solventless Elastomeric Polyurethane immediately after the Prime Coat on the Interior Surface of the Tank including Roof and Rafters.

• Estimated Cost for Applying the Coat was $30K