Case Studies

Project:

Inversa was asked to perform a full condition assessment work on Corrugated

Metal Pipe (CMP) in a large Municipality as part of a long term asset management plan. Asset Details:

• 1800 mm diam.; 179.0 m length; 1.0 m in depth;
  

Project Scope:

InScribe™ visual condition assessment, inSight Lite and inSight™ BCT, Engineering

certified report, including a Rehabilitation Plan.

Results:

• 26 visual indicators were recorded;

• InSight™ Lite anomalies were identified;

• 6 voids were observed, 9 inSight™ BCT images were completed;

• Severe erosion, sinkhole and downslope movement of outlet embankment;

• Separated joints were observed with through-wall corroded couplers and backfill material;

• Area of through-wall corrosion holes with visible substrate along invert were observed.

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Rehabilitation Plan:

1. Flow By-pass;

2. Clean and Preparation;

3. Grout Injections;

4. Maintenance Work; and

5. Concrete Paved Invert (CPI)

Cost Estimates: The estimated cost (high level) for the proposed work is $300,000.00.

Background Pilot Project

• 22 high value assets (deeply buried, high traffic, costly and disruptive replacements)

• Level 1 screening, BCT imaging and rehabilitation planning

• Results: Over $4 million in identified savings

• Led to a RFQ for a long term asset management program in which Inversa was the selected bidder

Current Project: 3-5 Year Asset Management Program

> LEVEL 1 SCREENING

• Force ranked system to ensure consistency

• Designed to be highly repeatable and trendable

> LEVEL 2 SCREENING

• Soil voids ultimately cause CMP assets to fail

• Conclusively verifies and quantifies the severity of soil voids

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Rehabilitation Planning

• Generates 50-75% savings, compared to asset replacement

• Several product options give asset owners the best choice for each asset

• Safely stabilize roadway infrastructure while avoiding the social, economic and environmental impacts of asset failure

Result

Over $ 102,000,000 in savings after only 2.5 years of the program

Project:

Full annular voids between the existing and the sliplined corrugated metal pipe (CMP). Inversa was to verify grout placement and quantify potential voids between the host pipe and new sliplined pipe. Asset Details:

36” diam., 100.5 ft length, 15 ft depth of fill.

Project Scope:

InScribe visual condition assessment and inSight Lite. Engineering sealed report including a Rehabilitation Plan.

Results:

• Severe sinkhole was noted;

• One (1) visual indicator was observed;

• Pipe invert found to contain through-wall corrosion;

• inSight™ Lite assessment identified areas of full annular void between the original pipe and the Sliplined CMP;

• Condition: Poor;

• Outcome: Rehab Recommended – Cured-in-Place Pipe (CIPP);

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Rehabilitation Plan:

• Flow By-pass

• Clean and Preparation;

• Grout Injection of Annular Space;

• Maintenance; 
- Brush tree cutting (Remove large vegetation present near the asset at the outlet embankment); 
- Erosion Control (Install adequate erosion and sedimentation control measures in order to stabilize the inlet embankment)

• Cured-in-Place Pipe (CIPP);

Cost Estimates:

• The estimated cost for the proposed work is $125,000.00 USD

• Return on Investment (ROI) – Aluminized CMP Replacement : $ 200,469.25 USD

• Return on Investment (ROI) – Concrete Replacement: $ 469,673.70 USD

Total ROI for Project $ 670,142.95 USD

Project:

As part of a large scale asset management program, Inversa was performing full condition assessments on large diameter (CMP) culverts.

Asset Details:

42” diam., 67.2 ft length, 5 ft depth of fill. Project Scope:

InScribe™ Visual Condition assessment, inSight Lite and inSight™ BCT. Engineering sealed report including a Rehabilitation Plan. Results:

• InSight™ Lite observed potential voids;

• InSight™ BCT scans were taken-4 voids were observed, 8 inSight™ BCT images were completed;

• Streambed material buildup within the pipe barrel;

• Eight (8) visual indicators were observed;

• Severe through-wall corrosion present along the pipe haunches;

• Condition: Poor

• Outcome: Rehab Recommended – Sliplining

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Rehabilitation Plan:

1. Flow by-pass;

2. Cleaning and preparation;

3. Hydrophobic Chemical Grout Injection;

4. Maintenance Work; - Slope Repair (Repair the identified scour holes); and - Pipe Install Repair (Repair deficient joint V-3 with an appropriate repair method approved by a design engineer

5. Sliplining.

Cost Estimates:

• The estimated cost for the proposed work is $ 121,500.00 USD

• Return on Investment (ROI) – Aluminized CMP Replacement : $ 52,601.76 USD

• Return on Investment (ROI) – Concrete Replacement: $ 222,607.01 USD

Total ROI for Project $ 275,208.77 USD

Project:

Inversa was asked to provide a QA/QC assessment on a pipe which had previously been sliplined on a High Density Polyethylene (HDPE) culvert with voids in the annular area due to improper grouting procedures.

Asset Details:

910 mm diam., 22.20 m length, 1.0 m depth of fill.

Project Scope:

InScribe™ Visual Condition assessment, InSight Lite, InSight™ BCT, and inspection with endoscope camera at specific locations.

Results:

• InSight™ Lite observed potential voids;

• InSight™ BCT scans were taken-8 significant voids were observed within the annular section, 10 inSight™ BCT images were completed;

• Endoscope camera inspections displayed visible voids with the annular section between the host and Sliplined culverts;

• Condition: Fair;

• Outcome: Maintenance Recommended – Grout Injections at all identified voids;

• SoilSightTM Pipe Map and insightTM BCT results to be utilized to help determine location of grout injections and to help estimate material volume requirements and insure Slipline is fully structural.

Project:

Inversa was asked to perform a full condition assessment on a water dam asset which had previously been sliplined within a HDPE culvert with severe dent/bulges.

Asset Details:

• 762 mm diam., 20.55 m length, 10.0 m depth of fill

• Conduit was rehabilitated by means of HDPE Slipline

• A severe dent/bulge was identified following the Slipline

Project Scope:

InScribe™ Visual Condition assessment, inSight Lite and inSight™ BCT. Engineer certified report, including Rehabilitation recommendations.

Results:

• InSight™ Lite observed potential voids;

• InSight™ BCT scans were taken-3 voids were observed at the severe dent/bulge, 14 inSight™ BCT images were completed;

• Outcome: Three (3) alternatives were provided to the client. Recommendations included:

  • Hydraulic Study

  • Grout injections

  • Partial rehabilitations/repairs

  • Conduit replacement by means of open trench installation