How to Apply the Virginia Underground Utility Damage Prevention Act to a Jack and Bore Operation: A Case Study. Jessica M. W. Hou, P.E.

Transcription

1 How to Apply the Virginia Underground Utility Damage Prevention Act to a Jack and Bore Operation: A Case Study Jessica M. W. Hou, P.E., BCEE

2 Agenda What is a jack and bore? What is does the Underground Utility Damage Prevention Act say? Description of Project Resolution Moving forward

3 What is a jack and bore? A tried and true method of horizontal boring: Dig a pit on either side of a roadway, stream, or obstruction to be crossed Lay a boring machine in the pit, on tracks Insert an auger into a casing The machine will push the auger and casing (jacking) into the ground simultaneously, while a cutting head bores through the ground (boring). The auger carries the debris back to the pit.

4 What is a jack and bore? After casing is installed, the carrier pipe (which carries the fluid in question) is run through the casing and supported by spacers. Variations Guided Boring Machines, etc. Maintain grade by lasers, pilot tubes

5 Underground Utility Damage Prevention Act M.HTM

6 Underground Utility Damage Prevention Act Also called the Miss Utility Act 20VAC Requirement for trenchless excavation. Any person conducting trenchless excavation shall take all reasonable steps necessary to protect and support underground utility lines. These steps shall include, but are not limited to the following:

7 Underground Utility Damage Prevention Act 1. The excavator should verify that all utility lines in the area are marked; 2. The excavator shall ensure that bore equipment stakes are installed at a safe distance from marked utility lines; 3. When grounding rods are used, the excavator shall ensure that they are installed at a safe distance (at least 24 inches plus the width of the utility line, if known) away from the marked or staked location of utility lines;

8 Underground Utility Damage Prevention Act 4. The excavator shall ensure sufficient clearance is maintained between the bore path and any underground utility lines during pullback; 5. The excavator shall give special consideration to water and sewer systems within the area that cannot be located accurately;

9 Underground Utility Damage Prevention Act 6. Unless prohibited by other laws, ordinances, regulations, or rules of governmental and regulatory authorities having jurisdiction, the excavator shall expose all utility lines which will be in the bore path by hand digging to establish the underground utility line's location prior to commencing bore. For a parallel type bore, unless prohibited by other laws, ordinances, regulations, or rules of governmental and regulatory authorities having jurisdiction, the excavator shall expose the utility line by hand digging at reasonable distances along the bore path;

10 Underground Utility Damage Prevention Act 7. The excavator shall ensure the drill head locating device is functioning properly and within its specification; 8. The excavator shall visually check the drill head as it passes through potholes, entrances, and exit pits; and 9. If the depth indicated by the locating device is lower than the bottom of the pothole or pit, the excavator shall cease boring until the hole/pit can be hand excavated further to maintain a visual inspection of the drill head.

11 The Project City of Norfolk PS 34 Service Area Phase 2 : Water Main, Force Main, Gravity Sewer

12 Trenchless crossing needed across West Little Creek Road at Diven Street due to high traffic levels The Need

13 Pipes to Cross Force Main: 12-inch DIP in a 24-inch Steel Casing (0.375-inch thickness) horizontal (no slope) Gravity Main: 10-inch DIP in a 24-inch Steel Casing (0.375-inch thickness) at a slope of 1%

14 Plan View of Double Jack and Bore

15 Test Holes Note: 13 test holes just in the intersection alone Utilities located included: Gas Electric Telephone Fiber Optic Water

16 Concerns of Fiber Optic Utility Owner Originally installed by HDD exact depth unknown, could not be confirmed with asbuilts Also depth could vary across intersection Surface locating equipment could not be relied upon Unusual readings Five test pits were dug just on this line across intersection including two locations directly on the pipe alignments

17 Profile of Gravity Sewer Over two feet from bottom of gravity sewer casing to top of fiber optic bundle at crossing location

18 Profile of Force Main Over two feet from bottom of force main casing to top of fiber optic bundle at crossing location

19 Section of Jacking Pit (Looking North)

20 Section of Receiving Pit (Looking South)

21 Jacking Pit as we begin on Nov 16, 2012

22 Receiving Pit

23 First To Do: Pilot Tube for Force Main

24 Shutdown! Stopped when pilot tube was almost across road Call from SCC to Contractor stop work or risk losing license Reason cited was that fiber optic line was not fully exposed prior to and DURING trenchless excavation Cited Item 6: the excavator shall expose all utility lines which will be in the bore path by hand digging

25 How can we expose the fiber optic line? It is below the jack and bore excavation and would compromise the security of the excavation This type of engineered bore requires soils to be undisturbed so that voids do not form outside of casing Would require large excavation due to the foot depth of the line that would shut down eastbound traffic on Little Creek Road Requirement to expose all utilities during excavation is done with regard to small HDD due to past history with damage

26 City and Contractor on the Same Side! Right-of-Ways Excavation and Restoration Manual is an ordinance in the jurisdiction in question, which prevails over the procedures outlined in Item 6 City stated that Contractor has satisfied requirements of manual by due diligence with test hole data No injunction can be granted by SCC to stop work, since there is no life safety issue (cannot be caused by potential damage to communication infrastructure)

27 Restart work on Tuesday, November 20, 2012 Finish pilot tube installation for force main

28 Casing for Force Main

29 Augers in Casings

30 Jacking of Casing

31 Casing Appears!

32 Carrier Pipe with Spacers

33 Repeat with Gravity Sewer Pilot tube Casing/Auger Carrier Pipe No further issues No obstructions or damage to existing utilities

34 SCC Probable Violation Case # Webb Inc. 11/19/2012 Notice of Probable Violation issued to Contractor Because fiber optic line was not exposed during trenchless installation Discussed at December meeting of SCC Advisory Committee Meeting City of Norfolk, Contractor, Engineer invited to February SCC Advisory Committee Meeting

35 Arguments 1. City of Norfolk ordinance prevails over SCC ordinance Contractor/Engineer due diligence 2. A jack and bore operation is not the same as a HDD operation that would install telecommunications lines or service lines Jack and bore is an engineered bore on grade If due diligence is performed ahead of time on utility locating, and jack and bore was designed around this information, intent of SCC ordinance was satisfied with regard to damage prevention

36 Discussion SCC Advisory Committee s council of advisors Jack and bore was considered trenchless technology and code fully applied Discussed difference between HDD and jack and bore Interested in due diligence how many test pits; what spacing was How jack and bore worked latest technologies Fiber optic utility owner was not present

37 Resolution SCC Advisory Committee agreed (not unanimous) All fines/violations were lifted City of Norfolk and Gannett Fleming are invited to be involved in committee to revise of ordinance to address these issues

38 Upcoming Conference Virginia Damage Prevention Conference 2013 Virginia Beach, Virginia April 16-18, 2013 Supported by: Division of Utility and Railroad Safety State Corporation Commission Virginia Utility Protection Service, Inc. Breakout session: Issues with Directional Drilling