Let’s start with drilling fluid. In the past pretty much “anything goes” was the norm when discussing drilling mud for HDD installations. If a contractor was drilling under a river, many times the river water would be used to mix the drilling mud. Not anymore. Most contracts now specify that the water used for the drilling fluid must come from a potable source. This means water must be hauled from a fire hydrant or other approved drinking water source. Another change centered around drilling fluid is the type of mud and additives that can be utilized. Many HDD contractors are required to utilize drilling fluids and/or additives that are NSF 60 approved. The NSF 60 certification sets health effects criteria for many water treatment chemicals including well drilling aids (drilling fluids). This means that some drilling fluids/additives that inhibit clay swelling or increase viscosity/gel strength may not be acceptable for use in a horizontal bore drilled for a pipeline installation, and others that are important to control loss of fluids are simply not allowed.
How contractors handle/control the mud during and after the drilling process is also a major issue during HDD projects. In the past, it was common to leave the drilling fluids and spoils on the pipeline right of way (ROW) or find a local farmer to accept the cuttings. Additionally, standard practice years ago was for the pipeline company to be responsible for the excess drilling fluids and spoils. Fast forward to 2014 and in most instances the HDD contractor is required by contract to remove the drilling fluids and spoils, and dispose of the waste in a well-documented and legal manner. This means that now the horizontal driller is responsible for containment, solidification, transport and disposal of all drilling generated waste from the project. This can be a very expensive item for the contractor, especially in remote drilling locations.