Presentation Objectives Provide a description of how Directional Boring works Cover the basics for planning a Directional Bore Discuss the advantages

Transcription

1 Directional Boring { An Introduction to the HDD Process

2 Presentation Objectives Provide a description of how Directional Boring works Cover the basics for planning a Directional Bore Discuss the advantages & limitations of Directional Boring

3 What is Directional Boring? A method for installing pp pipe underground without trenching, where the equipment is able to be guided below or around obstacles

4 Process: Step 1 Step 1 the Pilot Bore A pilot hole is drilled beginning at an adjustable angle relative to the surface which continues under and across the obstacle along the designed profile

5 Step 1: Directional Control The directional control is brought about by a varied bevel on the drill head. Apply force with out rotation to change direction Apply force with rotation to continue on the same trajectory

6 Step 1: Electronic Guidance Information about the roll, pitch & depth of the drill housing underground is communicated using a radio frequency tracking system. Commonly referred to as a walkover locating system, since a locator needs to walk with the progression of the drill housing along the bore path

7 Process: Step 2 Step 2 the Preream The bore hole may need to be enlarged to a greater diameter depending on what size pipe or how many pipes are being installed The process of successively increasing the diameter of the bore hole is called prereaming

8 Step 2: Reamers Reamer designs vary greatly for different soil conditions Often, you may use a combination of reamer sizes and designs to not only cut the bore, but clean the bore hole of solid material and also stabilize the bore hole

9 Process: Step 3 Step 3 the Pullback Once the bore hole is enlarged to the proper diameter Connect to the pipe product and Pullback to the bore machine

10 Step 3: Pullback Tooling The reamer continues to cut material during the pullback to reduce pullback pressure A swivel is introduced between the reamer and the pipe pp to eliminate rotational binding downhole during pullback A mud tight pipe puller is connected to the pipe to ensure no drilling mud enters the pp pipe during pullback

11 Process: Full Sequence Animation

12 Typical Pipe Materials for HDD HDPE Pipe Boregard Pipe (PVC sch40) Picking the appropriate pipe material for a directional bore is a very important part of setting up a successful installation Not every pipe material makes sense for every directional boring application

13 The Byproduct of Directional Boring Directional Boring s main byproduct the bore mud or returns that flows back to your entry & exit pits during the process. Bore Mud is in large part the spoils from the horizontal ontal hole you are cutting to place your pipes. The disposal cost of bore mud remains one of the main costs for the Directional Boring process

14 Compaction around the Directional Bore Sand Clay A study has conducted by Arizona State University to confirm compaction around pipes that have been installed by directional bore These photos represent directional bores that have been in the ground for 6 months and have no annular space around the pipes

15 Setting up a Directional Bore Various factors contribute to determining if directional boring is feasible for a specific site:

16 Determining Setup Space Does the site have an access point the equipment can fit in? When setting up a directional bore you must: Determine setup space required for the drill rig Determine laydown area behind the exit pit for pulling the pipe back Determine drilling safe window from existing utilities

17 Protection of Existing Utilities Call in USA Locates Obtain As Built Maps prior to mobilization Use secondary utility locator in private property Confirm size & depth of all existing utilities by potholing Record: size, depth, & location

18 Determine Bore Profile After the depth of all existing utilities have been located A safe drilling window can be established.

19 Bore Profile Documentation Every General Contractor/Owner that implements directional boring needs to receive an accurate bore profile or Borelog. A Borelog is a record of the depth the directional bore has drilled too for each full rod in the directional boring machine This record eod could then be converted to a profile for As Built records.

20 Cost Determiners There are a few major cost determiners in with directional boring Amount of setups Multiple setups can add considerable time to a project Length of bores Bores in excess of 500 can require additional preparation, increasing cost Amount of conduits in each bore Diameter of bore increases adding prereaming to the sequence & added mud disposal

21 Design Ideas to Lower Costs

22 Directional Boring Limitations Soil conditions/length of pipe drives equipment selection Not suitable for small sites Dense utility areas complicate obtaining a window Concrete encasement

23 Directional Boring Advantages Minimal i disruption i to environment Minimal restoration needed Permits are easier to obtained Minimize traffic control Cost reduction Achieve Ahi depth of cover faster Suitable for a variety of soil conditions Safer construction methods for workers