Posted on August 23, 2022 by Mike

As HDD contractors, we have seen a complex project or two. Sure, most jobs only involve installing a couple of wells under a building, and then we’re done. But plenty involve much more than that. We often deal with multi-year, multi-phase projects that might even include multiple remediation contractors all doing their thing.

This type of complex project can be a headache for the remediation consultant’s project manager. Keeping everything moving and avoiding interference between the various elements requires a lot of coordination. Sequencing the aspects of a large project can be daunting, but we can offer a few tips in how to include HDD work in the mix.

Optimize your Excavation Pits

Some projects include significant excavation to remove contaminated soil, pull out leaking USTs, or other activities. These project scopes generally require backfilling the excavations with clean fill followed by surface restoration.

Sure, we can drill in clean, homogeneous fill as easily as native soil. We can even cut entry pits in brand new asphalt. But sometimes if you think about it, you can put that excavation to use for your directional drilling!

On one project in Colorado, we actually ran a small rig down a ramp into the excavation in order to drill directly into the sidewall (observing all safety guidelines for slopes, etc., of course). This approach provided access to install horizontal sparge wells under a convenience store. Without lowering the entry elevation to within the tank excavation, we would not have had adequate setback to stay within the property boundary.

A little sequence juggling solved a difficult well geometry problem and even saved the owner some money. And we didn’t tear up brand-new paving with entry pits and well vaults…

Don’t Forget: Directional Rigs Can Steer

Consider your order of operations when installing both vertical and horizontal wells. Although we all like to work on uncluttered playing fields, sometimes it makes more sense to install your vertical wells first and then install the horizontal ones later.

If there are tight tolerances between wells, we can generally steer to avoid collision (although we prefer to stay at least 5-7 feet away from all vertical wells). Vertical drillers can’t steer. They don’t know exactly where their drill bit is laterally once they get beyond a few feet deep (hollow stem augers are notorious for walking around horizontally….).

Complex Project Spawns Cross-Activity Complications

On a recent project, our bore path crossed an area that had previously been riddled with vertical injection points that we hadn’t been cautioned about. As we traversed this area, we had several inadvertent returns of drilling mud to the ground surface along these weak spots in the soil structure.

At the same time, a paving contractor had delays, and was laying down tarmac for an air field taxiway along a path that intersected our well. As you might imagine, drilling fluid frac-outs are not terribly compatible with placing special cementitious subgrade for aircraft-grade pavement.

The resulting scheduling delays and standby time presented a huge problem for the project. Oh – and the paving contractor kept running equipment over our assembled pipe, causing damage that needed to be repaired.

 

Sometimes the schedule dictates that certain activities overlap. However some work elements are more compatible with one another than others.

At the very least it would have been nice to know in advance that our well path was crossing a pin cushion!

Sometimes you might just hope to avoid conflict by rearranging the sequence of operations. However sometimes you can actually add synergies that enhance the project schedule. Having been around the block a time or two, we might have some good suggestions. So, don’t be afraid to tell us the whole story of what’s going on at your site.

 

Tags: #complex projects, #excavations, #project management, HDD

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