Fun With Foam Deep Injection

Transcription

1 Fun With Foam Deep Injection Stephen Cruise Environmental Resource Specialist

2 Where were we?

3 Original Project Culvert to Bridge Fish Passage Improvement

4 Modular Concrete Block bridge design Pacific Bridge and Construction Excavated into bedrock Simulated Streambed with 14 Active Channel Width Design Notes Height (ft) Cross-Section A-A' Station (ft) Aug Cross-Section B-B' Heig h t (ft) Station (ft) Aug 24 09

5 Design Notes

6 Construction Issues Exposed To Nature Overexcavated into bedrock to create a flat base Underestimated the number of boulders for abutment protection Underestimated stream s ability to scour

7 with stream flowing under abutment. Led To Structural Concerns Block undermined approx. 18 at downstream end (block dimensions are 2 6 wide and 1 3 tall)

8 Possible Solutions Do nothing Reinstall bridge components Flowable fill Form and pour concrete Foam injection

9 Possible Solutions Do nothing Reinstall bridge components Closing a dead end road Cost of breaking apart and reinstalling components Potential damage to structural members Flowable fill Form and pour concrete Foam injection

10 Do nothing Reinstall bridge components Flowable fill Potential for release Stream diversion ph concerns Unsure if total void filled Form and pour concrete Foam injection Possible Solutions

11 Possible Solutions Do nothing Reinstall bridge components Flowable fill Form and pour concrete Permits Man power Will it fill the voids? Stream diversion ph concerns Confined working conditions Foam injection

12 Do nothing Reinstall bridge components Flowable fill Form and pour concrete Foam injection Possible Solutions Controllable Neutral ph No permits No stream diversion Minimal environmental impact Cost effective Minimal failure risk

13 Foam Injection Process Contracted with Uretek ICR Oregon to use their proprietary high density structural grade polymer to fill the voids around and beneath the abutment.

14 Foam Injection Process Step 1: Site preparation Washington County maintenance crew worked to divert the flow away from the scoured abutment.

15 Foam Injection Process Step 2: Drill holes and drive injection ports into voids

16 Foam Injection Process Step 3: Pump polymer into voids, monitoring pressure until it reaches refusal

17 Foam Injection Process Step 4: Repeat injections as necessary until all voids are filled. Step 5: Clean up excess

18 Foam Injection Benefits No diversion necessary Polymer forms around rocks, cementing them in place Fully expands in less than 1 minute Prevents future loss of structural bearing pad Fills the void below the abutment Environmentally neutral

19 Structural strength characteristics are less than concrete Scour potential remains from exposure to abrasive stream materials Unknowns The bane of engineers existence. Foam Injection Concerns

20 Technical Information Less than 1 minute for full expansion 90% Strength in 15 minutes Hydroinsensitive ph of the expanding polymer in water is 7.2 Escaped material floats and can be easily captured and removed from the water surface. Compressive strength of the Uretek 486 polymer is approximately 8000 lbs/sq ft, similar to very stiff to hard soil.

21 Cost comparison to another county bent foundation scour repair project VS

22 Cost Comparison to another county bent foundation scour repair project Deep Injection Foam Fill $8200 for materials and labor provided by Uretek $2000 for Washington County maintenance crew site preparation, engineering and environmental oversight, and contract administration Total Cost approximately $10,000

23 Cost Comparison to another county bent foundation scour repair project Concrete Form and Pour (using existing programmatic permits and exempt permitting strategy) $80,000 for diversion work $20,000 for construction work, engineering and environmental oversight, and fish salvage permits and activity Total cost $100,000. Without the programmatic permit, the cost would have been approximately $250,000

24 Results 5/17/11 Pre-repair Today 9/21/12

25 Stream Response Upstream Cross-Section Height (ft) Station (ft) Aug 24 09

26 Stream Response Upstream Cross-Section Height (ft) Station (ft) Aug Sept 16 10

27 Stream Response Upstream Cross-Section Height (ft) Station (ft) Aug Sept Jun 21 11

28 Stream Response Upstream Cross-Section Height (ft) Station (ft) Aug Sept Jun Sept 24 12

29 Stream Response Downstream Cross-Section Height (ft) Station (ft) Aug 24 09

30 Stream Response Downstream Cross-Section Height (ft) Station (ft) Aug Sept 16 10

31 Stream Response Downstream Cross-Section Height (ft) Station (ft) Aug Sept Jun 21 11

32 Stream Response Downstream Cross-Section Height (ft) Station (ft) Aug Sept Jun Sept 24 12

33 Final Thoughts Deep injection foam has its place in the bridge maintenance toolbox Long term monitoring will tell us the effective lifespan of the foam repair. Don t t fight mother nature, gentle persuasion works best. Addressing problems during construction can reduce maintenance nightmares, even if it affects the construction budget or completion date.

34 Thank you, questions?